국내 고도성장기 이후 본격 건설되기 시작한 사회 기반 시설물은 노후화가 빠르게 진행되고 있다. 특히 사고 발생 시 대량 인명 피해로 직결될 수 있는 교량, 터널 등의 대형 구조물들에 대한 안전성 평가가 필요하다. 하지만, 기존의 유선 센서 기반의 SHM을 개선한 무선 스마트 센서네트워크는 짧은 신호도달거리로 인해 경제적이고 효율적인 시스템 구축이 힘들다. 따라서 LoRa LPWAN시스템은 사물인터넷의 확산과 더불어 저전력 장거리통신이 각광을 받고 있으며, 이를 구조건전성 모니터링에 응용함으로써 경제적이면서도 효율적인 SHM 구축이 가능하다. 본 연구에서는 LoRa LPWAN의 구조건전성 모니터링에 적용 가능성을 검토하고 비면허 통신 대역을 사용함으로 인해 발생하는 채널간의 충돌을 해결하면서 대역폭을 효율적으로 활용할 수 있는 채널 기반의 LoRa 네트워크 운영방법을 제안한다.

PURPOSES : The purpose of this study is to compare applicability, explanation power, and flexibility of traffic accident models between estimating model using the statistical method and the machine learning method. METHODS: In order to compare and analyze traffic accident models between model estimated using the statistical method and machine learning method, data acquisition was conducted, and traffic accident models were estimated using statistical methods such as negative binomial regression model, and machine learning methods such as a generalized regression neural network (GRNN). Then, the fitness of model as R2, root mean square error (RMSE), mean absolute percentage error (MAPE), accuracy, etc., were determined to compare the traffic accident models. RESULTS: The results showed that the annual average daily traffic (AADT), speed limits, number of lanes, land usage, exclusive right turn lanes, and front signals were significant for both traffic accident models. The GRNN model of total traffic accidents had been better statistical significant with R2: 0.829, RMSE: 2.495, MAPE: 32.158, and Accuracy: 66.761 compared with the negative binomial regression model with R2: 0.363, RMSE: 9.033, MAPE: 68.987, and Accuracy: 8.807. The GRNN model of injury traffic accidents also showed similar results of model’s statistical significance. CONCLUSIONS: Traffic accident models estimated with GRNN had better statistical significance compared with models estimated with statistical methods such as negative binomial regression model.

본 연구의 목적은 ‘한국 시·군·구의 네트워크 중심성 측정’이다. 이러한 연구목적의 달성을 위해 전국 229개 시·군·구 간의 중심성 크기를 ‘2015년 인구주택총조사’의 전국 229개 시·군·구의 통근통행 O-D 행렬을 이용하여 점수 형태로 측정하였다. 본 연구에서 전국 229개 시·군·구를 대상으로 중심성 점수를 측정한 것은 기존의 연구 중에는 전국 229개 시·군·구 전체를 대상으로 조사한 사례가 없기 때문이다. 본 연구에서 측정한 중심성은 세가지인데, 연결정도 중심성과 고유벡터 중심성, 그리고 연결정도 중심성과 고유벡터 중심성을 일반화시킨 보나시치 베타 중심성이 그것들이다. 본 연구에서 연결정도 중심성, 고유벡터 중심성 및 β＜ 0 인 보나시치 베타 중심성을 사용하여 전국 229개 시·군·구의 세가지 중심성을 구하고, 이 세가지 중심성의 결과값을 비교한 결과, 지역 간 상호관계는 기존 연구에서 나타난 상호보완적 관계가 아니라 상호경쟁적 관계임이 명확하게 드러났다. 특히, 지역 간 상호관계가 상호경쟁적 관계일 경우 보나시치 베타(β＜ 0) 중심성으로 측정하여야 정확성이 높은 중심성 결과값을 얻을 수 있는 것으로 나타났다.

현행법상 임시조치 제도는 사생활 침해 또는 인격권 등의 침해를 받은 자의 법익을 보호하려는 취지에서 2008년 「정보통신망 이용촉진 및 정보보호 등에 관한 법률」 개정을 통해 도입되었다. 정보통신망법이 도입한 임시조치 제도가 그동안 순기능적 역할을 담당해 왔음을 부인할 수는 없다. 하지만 임시조치 제도가 표현행위자의 표현의 자유를 과도하게 제약하고 국가사회생활에서 합당한 문제제기 내지 비판을 봉쇄하는 수단으로 변질되고 있음도 역시 부인할 수 없는 현실이다. 특히 현행법상의 임시조치 제도는 권리침해를 주장하는 자의 일방적 주장만으로 발동될 수 있어서 표현행위자의 표현의 자유보다 권리침해를 받은 자의 권익을 더 보호한다는 비판을 받는다. 따라서 표현의 자유와 권리침해를 받은 자의 권익이 합리적 조화를 이루어 양 기본권이 최대한 실현될 수 있도록 제도를 형평에 맞게 개선을 할 필요가 있다. 임시조치 제도를 개선하는 방안으로는 첫째, 현행 임시조치 제도를 사실상 폐지하고 권리침해를 받은 자에게 방어주장의 기회를 보장하는 반박내용의 게재를 허용하도록 하는 방안을 생각할 수 있다. 이 방안은 권리침해를 주장하는 자와 표현행위자 사이에서 적절한 조화와 균형을 도모한다는 점에서 가장 혁신적이라 할 수 있다. 둘째, 현행 임시조치 제도의 기본적 골격을 유지한다고 하면 권리침해를 받은 자의 소명과 함께 분쟁조정기구에의 조정 신청 등의 요건을 부가함으로써 권리침해를 받은 자가 임시조치 제도를 악·남용하는 것을 방지할 필요가 있고 임시조치 기간을 단축할 필요가 있다. 셋째, 임시조치 발동요건을 현행 방식 그대로 답습한다면 정보게재자와 권리침해를 주장하는 자 사이에서 최소한의 균형 유지를 위해서 임시조치 기간의 단축과 임시조치 기간 경과 후 정보게재자의 재개시청구권과 그 행사요건, 절차 등을 법률에 명시할 필요가 있다.

The latest catchword “beat call” comes from Japan. It was originally one of the Live culture of the concert. In order to express their affirmation and support for the idol singers on stage, fans waved fluorescent sticks and shouted for refueling and inspiration to create a warm atmosphere together. With the high frequency use of call, it gradually extends from the entertainment field to other fields. Nowadays, call is not only applicable to this kind of idol assistance activities, but also can be expressed by call when you express support for a person, thing or thing. The “fight call” in aid culture has been rapidly disseminated in China through the help of network media. In order to make the speaker understand and make better use of “call” from the linguistic point of view, the semantics and characteristics of “call” as well as the applicable objects and users of “call” are analyzed with examples. It is found that “call” can arouse the acceptor's sense of participation, highlight the color of praise, and end the text. Better satisfy the expression of novelty and conformity psychology. Internet hotspot “call” is now widely used in the network media. With the news of Sina Weibo and People's Daily as corpus and the relevant content of language contact, this paper makes corresponding analysis on the origin, semantic components and grammar of the word “call”, the category and development course of the applicable context and the popular motivation of the word.

We present the first results of the invariant point (IVP) coordinates of the KVN Ulsan and Tamna radio telescopes. To determine the IVP coordinates in the geocentric frame (ITRF2014), a coordinate transformation method from the local frame, in which it is possible to survey using the optical instrument, to the geocentric frame was adopted. The least-square circles are fitted in three dimensions using the Gauss-Newton method to determine the azimuth and elevation axes in the local frame. The IVP in the local frame is defined as the mean value of the intersection points of the azimuth axis and the orthogonal vector between the azimuth and elevation axes. The geocentric coordinates of the IVP are determined by obtaining the seven transformation parameters between the local frame and the east-north-up (ENU) geodetic frame. The axis-offset between the azimuth and elevation axes is also estimated. To validate the results, the variation of coordinates of the GNSS station installed at KVN Ulsan was compared to the movement of the IVP coordinates over 9 months, showing good agreement in both magnitude and direction. This result will provide an important basis for geodetic and astrometric applications.

첨단 정보통신기술을 활용한 해양사고 감소를 위하여 국내외적으로 e-Navigation 관련 기술과 서비스에 대한 연구개발이 다양하게 진행 중이다. 이러한 기술과 서비스가 실제로 해상에서 사고예방에 기여하기 위해서는 선박에 관련 장비가 설치되어야 하며 법제적으로도 운영 조직과 시스템이 확충되어야 한다. 특히, 한국형 e-Navigation 사업으로 개발 될 초고속해상무선통신망(LTE-M망) 및 VDES, Digital-MF/HF 등 디지털 통신기술이 실행될 수 있도록 선박에는 관련 통신장비와 기술표준이 조속히 마련되어야 한다. 기존연구는 이러한 LTE-M에 대한 정책방안을 제시하지 못하는 문제점이 남아 있다. 본 연구에서는 한국형 e-Navigation의 효율적인 시행에 필요한 제도와 정책방안을 단기, 중기 및 장기로 나누어 식별하고, e-Navigation 핵심서비스, e-Navigation 통신망 및 운영시스템, e-Navigation 국제표준선도 기술 및 e-Navigation 서비스 활성화 분야에서 구체적인 방안을 제시하였다. 이를 위하여 해양수산부 주도로 추진 중인 한국형 e-Navigation 구축사업의 진도점검 자료에 기초하여 조사와 연구를 수행하였으며 관련분야 실무자 및 전문가들의 자문을 통하여 연구결론을 도출하였다. 본 연구의 결과로 제안된 정책들은 해양사고 저감과 해사산업 진흥 및 국민 안전을 위한 정부의 추가적인 정책 개발에 도움이 될 것으로 기대한다.

도시숲(Urban Forest)이란 도시에서 국민 보건 휴양･정서함양 및 체험활동 등을 위해 조성･관리하는 산림 및 수목으로 법적으로 정의되고 있다. 도시라는 공간에 존재하는 도시숲의 개념 및 범위는 각각의 상황과 여건에 따라 다양 하게 표현되고 있다. 본 연구에서의 도시숲의 범위는 자연적인 도시숲으로 도시내부 또는 도시에 인접하여 분포하는 산림으로 한정하였다. 도시숲은 도시생태계 내에서 다양한 공익적 기능을 수행 한다. 도시숲은 도시 기반시설로 도시환경의 보전과 개선을 위한 중요한 지역으로 볼 수 있다. 하지만 인간의 경제활동으로 인한 산림지역 훼손은 지속적으로 이루어지고 있으며, 그 결과 다양한 환경문제가 야기되고 있다. 도시지역 인근의 산림지역 또한 도시화로 인해 지속적인 축소가 되고 있다. 하지만 최근 산림청에서는 훼손되는 산림면적을 대신하여 도심 내 생활권도시숲을 확대하려는 노력을 기울이고 있다. 부산시는 서울을 포함한 수도권지역에 비해 도시숲 관련 연구가 체계적으로 이루어지지 않았고, 향후 지속적으로 조성될 생활권도시숲에 적합하고 건전한 생태적 식재관리를 위한 기초자료가 부족한 실정이다. 본 연구는 부산시 내 자연산림지역을 중심으로 도시숲의 식생구조를 살펴보고 식물사회네트워크의 구조를 규명하고자 시행되었다. 또한 본 연구의 결과는 도시숲 식생관리의 기초자료로 활용될 수 있을 것이다. 부산시 통계자료와 임상도, 현존식생도 등을 참고하여 도시숲 현황을 살펴보았고, 주요 군락을 중심으로 식생구조 조사를 현장에서 실시하였다. 조사된 자료를 바탕으로 층위별 상대우점치를 분석하였고 평균상대우점치를 도출하였 다. 층위별 종수 및 개체수를 살펴보았으며, 군락별 주요 수종의 흉고직경급별 분포도 분석하였다. 식물사회네트워크는 식물사회를 이해하기 위한 하나의 방법으로 기존의 식물사회학적 방법인 종간결합분석(interspecific association)과 사회연결망 분석의 프로그램을 활용하여 식물 사회의 연결망을 시각화하고 분석하는 것이다. 두 수종간 동반출현유무에 따라 χ²검정(Chi-square statistic)을 실시하였고, 그 결과를 토대로 식물사회네트워크를 구축하였다. 부산시 도시숲은 해안의 영향으로 곰솔림이 폭넓게 분포 하고 있었으며, 소나무림, 졸참나무림, 상수리나무림, 굴참 나무림, 신갈나무림, 개서어나무림 등 다양한 임상이 나타 나고 있었다. 비교적 도시화가 이루이지지 않은 기장군 일대와 인위적 간섭이 배제되었던 가덕도지역 식생이 상대적으로 양호하였다. 곰솔군락은 209개소에서 조사되었고 다른 군락에 비해 출현지역의 해발고도가 낮았다. 소나무군락 은 65개소에서 출현하였으며 곰솔군락에 비해 종다양성지수가 높게 나타났다. 졸참나무군락은 77개소에서 조사되었고 향후 부산시 도시숲에서 생태적 지위가 넓어질 것으로 판단되었다. 상수리나무군락은 주로 남향에서 출현하였으며 58개소에서 조사되었다. 개서어나무군락은 35개소에서 조사되었으며 다른 군락에 비해 교목층의 수고와 흉고직경이 컸다. 부산시 도시숲 식물사회네트워크 구조를 분석한 결과, 연결중심성은 사스레피나무, 근접중심성은 감태나무, 매개중심성은 광나무, 위세중심성은 마삭줄이 높았다. 그 외 팥배 나무, 팽나무, 굴참나무, 산뽕나무도 네트워크 내에서 중심성이 높은 것으로 분석되었다. 부산시 도시숲 식물사회네트 워크의 분석 결과로 볼 때, 시각화된 식물사회네트워크는 부산시 도시숲 식물사회 특성을 반영하고 있었고 식물사회학 분야에서 사용되어 왔던 성좌표 작성 방법의 한계를 극복할 수 있었다고 판단되었다. 식물사회네트워크 분석방법론은 식물사회의 본질적인 구조를 파악하는데 시도되는 하나의 방법으로 지속적인 연구가 필요하다고 사료된다.

In this study we present a new approach to estimating termite populations size. So far, termite researchers have been using the mark-capture-recapture method. This method has a disadvantage that measurement time is long and error range is large. To this end, we built an agent-based model to simulate termite tunneling behavior. Using this model, we made simulated tunnel patterns that are determined by three variables: the number of simulated termites (N), the passing probability of two encountering termites (P), and the distance that termites move soil parcels (D). To explore whether the N value can be estimated with a partial termite tunnel pattern, we generated four groups of tunnel patterns that are partially obscured in complete tunnel pattern image: (1) A pattern group in which the outer area of the tunnel pattern is obscured (I-pattern), (2) a pattern group in which half of the tunnel pattern is obscured (H-pattern), (3) a pattern group in which the inner region of the tunnel pattern is obscured (O-pattern), and (4) a pattern group combining I- and O-pattern (IO-pattern). For each group, 80% of the tunnel patterns were learned through a convolution neural network (CNN) and the remaining 20% of the patterns were used for estimating N value. The estimation results showed that the N estimates for the IO-pattern are the most accurate and are in the order I-, H-, and O-patterns. This means that the termite population size can be estimated based on tunnel information near the center of the colony.

Net neutrality, which has not been a problem, has recently become a problem for ISPs (Internet Service Providers), and their complaints have been paid by domestic platform companies, but overseas global IT companies such as Google and YouTube, generate huge revenues from domestic markets. In this situation, domestic IT companies claim that it is natural to impose more expensive charges or restrict speed on users who generate huge traffic. On the other side, however, the telecommunication network has become an essential public good that is essential to our everyday life, and because it has been given a monopoly position by a private company to efficiently respond to the explosive demand for telecommunication services, It is necessary to provide equal and universal service and fulfill public duty. In this paper, we deal with the network neutrality problem, focusing on the price elasticity between the CP (Contents Provider) and the ISP, rather than the user who is one side of the two-sided market for the already saturated satellites communication market. We present a game model that determines the optimal price for each platform by Nash equilibrium and analyze how the net neutrality affects CP according to the change of exogenous variables through the proposed game model.

There is growing interest in the various functions of urban green spaces that can improve urban resilience. Urban green spaces have an important role in wildlife habitat, climate and hydrological control, and recreation and outdoor activities. The connectivity of a green space network is known to control urban resilience by minimizing the disturbance caused by urbanization and climate change and strengthening the adaptation capacity. In this study, we analyzed the social-ecological network characteristics of green space in the city of Jeonju, South Korea. To analyze the ecological network, we defined wildlife habitat as the ecological node and used an index based on graph theory. We defined residential area as the social node, and we analyzed the accessibility of green space from the residential area to assess the social network. The results indicate that the green spaces in Jeonju are highly connected in the social and ecological perspectives on the fringe of the city. However, our founding also indicated that the social and ecological connectivity of the green space network in the downtown area should be improved. This study can be used as a basis for establishing an Urban Open Space Conservation Plan that considers the improvement of urban resilience in the future.

It is important to consider interaction between species in understanding structure and function of the biological community. Current ecological issues such as climate change and habitat loss emphasize the significance of the concept of species interaction in that varying species’ interaction across environmental gradients may lead to altered ecological function and services. However, most community studies have focused on species diversity through analysis of quantitative indices based on species composition and abundance data without considering species interactions in the community. ‘Ecological network analysis’ based on network theory enables exploration of structural and functional properties of ecosystems composed of various species and their interactions. In this paper, network analysis of Cheonggye stream as a case study was presented to promote uses of network analysis on ecological studies in Korea. Cheonggye stream has a simple biological structure with link density of 1.48, connectance 0.07, generality 4.43, and vulnerability 1.94. The ecological network analysis can be used to provide ecological interpretations of domestic long-term monitoring data and can contribute to conserving and managing species diversity in ecosystems.

이 연구는 1991년부터 2017년까지 발간된 「교정연구」를 대상으로 언어 네트워크 분석 (Semantic Network Analysis)을 통해 핵심 키워드의 중심성 분석을 하고자 한다. 이를 통해 우리나라 교정학 연구의 경향성을 파악하고 미래의 교정정책에 대한 방향성을 제시해 줄 수 있는 균형 잡힌 연구를 선택하도록 근거를 제공하는데 그 목적이 있다. 분석결과, 전반적으로 ‘교정’, ‘처우’, ‘방안’, ‘수형자’, ‘개선’ 등의 빈도수가 상대적 으로 높다는 것을 알 수 있다. 이는 「교정연구」의 연구주제들이 주로 수형자의 교정처우와 그 개선방안에 관련된 연구들이 많았음을 시사한다고 볼 수 있다. 각 시기별로 분석한 결과를 보면, 1991년부터 2000년까지는 ‘교정’이라는 키워드를 중심으로 ‘방안’, ‘처우’, ‘문제’, ‘방향’ 등의 순으로 연결중심성이 높게 나타났으며, 특히 ‘법’, ‘수형자’, ‘제도’, ‘개선’, ‘실태’, ‘범죄’, ‘행형’ 등의 키워드가 높은 연결관계를 형성하고 있었다. 초기의 연구는 주로 교정관련 제도나 정책, 교정의 이념 및 이론들이 연구주제로 주목받으면서 교정학의 정체성 확립을 위한 기반 연구들이 많이 진행된 것으로 보인다. 2001년부터 2010년 사이에 이루어진 연구들을 살펴보면 ‘교정’이라는 핵심 키워드 를 중심으로 ‘사회’, ‘개선’, ‘방안’, ‘소년’, ‘범죄’, ‘처우’, ‘제도’, 청소년’, ‘시설’, ‘프로그램’, ‘수형자’, ‘고찰’, ‘문제점’, ‘효과’ 등의 키워드가 연결중심성이 높게 나타났 는데, 이 역시 교정과 관련된 법･제도의 개선 및 당시 사회적 관심이 연구주제에 반영 되었다고 볼 수 있다. 특히, 이전 시기와 다르게 ‘프로그램’, ‘효과’, ‘영향’, ‘요인’ 등 의 키워드가 새롭게 등장하였다. 즉, 이 시기에서는 교정학의 연구주제가 프로그램의 효과성 분석이나 수형자 및 소년범 등의 행태에 초점을 맞춘 실증적 연구가 서서히 증대되고 있는 것으로 나타나 교정학 분야에 다양한 경험적 연구들이 다루어지기 시작했다는 것을 알 수 있었다. 또한 이 시기에 ‘지역사회’, ‘약물’, ‘보호관찰’ 등의 키워 드가 새로이 등장하면서, 당시 사회내 처우와 보호관찰 등에 대한 관심이 증가하고 있 었음을 알 수 있었으며, 약물범죄자의 교정 등 수형자의 개별처우 프로그램에 대한 실 증적 연구가 점차 연구주제로 선택되기 시작했음을 알 수 있었다. 마지막으로 2011년부터 2017년까지의 연구에서는 ‘교정’을 중심으로 ‘소년’, ‘방안’, ‘범죄’, ‘수용’, ‘시설’, ‘제도’, ‘재범’, ‘보호’, ‘치료’, ‘개선’, ‘효과’, ‘프로그램’ 등 의 순으로 가장 높은 연결중심성을 보여주고 있다. 2001-2010년 시기와 다르게 ‘소 년’이나 ‘청소년’ 등의 키워드가 연결중심성이 많이 높아진 것으로 분석되었으며, 특 히 이 시기에서는 ‘재범’, ‘치료’, ‘예방’, ‘가석방’ 등의 키워드가 새로이 연구주제로 등장하게 되는데, 이전 시기에 비해 범죄자의 재범방지에 관한 연구와 수형자의 치료 감호 등에 대한 연구주제가 선택되고 있으며, 범죄에 대한 사후적 분석보다 소년비행 이나 성인 범죄에 대한 사전적 예방이 근본적인 범죄대책으로 인식되면서 이에 대한 연구들도 활발히 이루어진 것으로 판단된다.

Currently, the commercialization of the 5th Generation (5G) service is becoming more prevalent in domestic communication network technology. This has reduced communication delay time and enabled large-capacity data transmission and video streaming services in real-time. In order to keep pace with these developments, K-water has introduced a smart process control system in water purification plants to monitor the status of the water purification process. However, since wireless networks are based on the public Long Term Evolution (LTE) network, communication delay time remains high, and high-resolution video services are limited. This is because communication networks still have a closed structure due to expense and security issues. Therefore, with 5G in its current form, it is very difficult to accommodate future services without improving the infrastructure of its communication networks. In recognition of these problems, this study implemented the authentication and management function of wireless networks on a wired network management system in the K-water Bansong water purification plant. The results confirmed that wired Local Area Network (LAN) services give a higher security performance than an expensive commercial wireless LAN system. This was achieved by using an Internet Protocol (IP) address management system of wired networks and the packet filtering function of the Layer2 (L2) switch. This study also confirmed that it is possible to create a wireless LAN service that is 3.7 times faster than the existing LTE communication network.

4차 산업혁명의 시대에 기업들은 다양한 기술들이 복잡하게 융합하면서 진 화하는 기술 환경을 이해하고 이로 인한 비즈니스 환경의 변화에 대응하는 것이 중요하다. 이를 위해 본 연구에서는 최근 기술개발 경쟁이 가속화되고 있는 자동차 분야의 10대 기업을 대상으로, 이들의 최근 6년간 미국등록특허 중 2개 이상의 이종 기술 분야에 동시 분류된 융합특허를 추출하여 소셜네트워크 분석을 수행하였다. 그 결과, 자동차 분 야의 융합에 관계된 기술의 수가 크게 증가하고 있으며, 기술간 융합이 더욱 강하게 이루어지고 있음을 확인하였다. 또한 Volkswagen, Ford, Hyundai 등 3개 기업은 기술융합 의 변화가 큰 기업으로, 특히 친환경 자동차 관련 기술에서 전략의 변화가 있는 것으로 분석되었다. 본 연구는 기업들이 네트워크 분석의 결과를 더욱 의미있게 활용할 수 있는 다양한 방법을 제시한 점에서 연구의 의의가 있다.

Introduction Japanese convenience-store (CVS) chain retailers have grown by establishing store networks. In fact, Seven-Eleven, Lawson and Family Mart continuingly have opened about 1000 new stores per year. The reason for the rapid growth of their store-networks is that a key aspect of a chain retailer’s marketing strategy is the number of stores its needs to reach its customers (Srinivasan et al. 2013). In particular, CVS chain retailers seek to open new stores and obtain spatial dominance in a particular geographical area, which is called “area-dominance strategy,” so they can save on logistical costs, increase consumer proximity and loyalty, and prevent rival from opening new stores in the area (Ogawa 2004, Tamura 2014, Nishida 2014). Thus, a retailer’s decision of how to expand store-network in a given regional market is important to improve its sales. However, little attention has been paid to this problem in Japanese academic research. This study attempts to explain the influence of entry of rivals on a focal retailer’s store-network in regional markets of Japanese CVS industry. Especially, the author focuses on the regional competition between a focal retailer who is the first entrant and rivals who are late entrants in the region. First, we review prior research, and then propose hypotheses about the influence of entry of rivals, the degree of dominance of a focal retailer, and entry of rivals in multiple regions, on the number of the focal retailer stores. This is followed by an empirical analysis with panel data. Last, we discuss some implications and direction for future research. Literature Review and Proposed Hypothesis Entry of rival stores Prior research suggests that the existence of rival chain stores in the same market decreases the store-revenue of the focal retailer (Erickson et al. 2013, Nishida 2014).When rival retailers open the large number of new stores in a regional market, the focal retailer may be taken away their business of existing stores and latent new stores, so the focal retailer will be forced to close existing stores and slow down the pace of opening new stores. Then, we propose following hypothesis: H1: In a regional market, the higher the number of net increase of rival stores is, the lower the net increase of focal retailer stores is. Dominance of the focal retailer According to prior research, CVS chain retailers benefit from area-dominance (opening own stores aggressively in a given region), because it enables retailers to reduce their distribution and promotion cost, increase consumer loyalty and their power against manufactures (Ogawa 2004, Tamura 2014, Nishida 2014). If the focal retailer has already established a high density store-network, and had strong relationships with its customers and manufactures in the regional market, they will be less likely to suffer from entry of rival chain stores, and they will be able to continue expanding their store-network. These arguments lead to: H2: In a regional market, the higher the degree of dominance of the focal retailer is, the smaller the negative effect of entry of rival stores is. Entry of rival stores in multi-market Though H1 and H2 do not consider multi-market competition among chain retailers, this macro-level competition may have a great impact on their competitive action in a given region (Chen 1996). When a rival entries to multiple regions simultaneously where the focal retailer has already operated, the focal retailer will delay its decision making and competitive responses, so the impact of entry of rival will be larger (Poter 1980, Ferrir 2001, Boyd and Bresser 2008). Therefore, we propose following hypotheses: H3a: The higher the number of regions which rival entry is, the bigger the negative effect of entry of rival chain stores is. H3b: The higher the number of net increase of rival stores across the regions is, the bigger the negative effect of entry of rival chain stores is. Methodology To test the proposed hypotheses (see FIGURE 1), we collected panel data from the Census of CVS Market, which includes the number of stores of Japanese CVS chain retailers in each prefecture. Due to the restriction of data availability, we treated prefectures as the unit of regional market, and focused on the cases that Lawson was the first entrant, and Seven-Eleven and Family-Mart ware the later entrants in prefectures. Accordingly, the sample was limited in space to 17 prefectures, and limited in time to the period from the year that Seven-Eleven or Family-Mart opened their stores for the first time to 2014. Results We tested the hypotheses using panel date analysis by fixed effects model. The estimated results are shown in FIGURE 2. Regarding our hypotheses H1, involving the negative effect of rival entry on the focal retailer’s store-network, is not supported. However, the interaction of “the dominance of the focal retailer” with “rival entry” and the interaction of “rival entry in multiple regions” with “rival entry” are significant, although their signs of coefficients differ depending on whether the rival is seven-eleven or family-mart. Thus, hypotheses H2 and H3b are supported in part. Implication and Future Research Our findings have several important implications. First, our empirical results suggest that the effect of rival entry on a focal retailer’s store-network depends on (1) rival’s position in CVS industry, (2) the focal retailer’s dominance, and (3) rival’s multiple entry. Second, when a rival has a superior position than the focal retailer, dominance advantage of the focal retailer increases the negative effect of rival entry, which is contrary to our expectation. This implies that enhancement of the density of own store-network will cause cannibalization, so each store of a focal retailer may be highly vulnerable to entry by a rival who has superior competitive position (i.e. Seven-Eleven). Finally, multiple entry by a rival in superior position reinforces the negative effect of their entry on expansion of the focal retailer’s store-network in the regional market. Though this study was a rare attempt to explain regional competition among Japanese CVS chain retailers empirically, it did not include the prefectures that Seven-Eleven and Family-Mart were the first entrants. This may limit generality of the empirical results, hence it is valuable to take this problem into consideration in future research.

This research was conducted to examine factors affecting tweens´ brand preference for mobile network choice decisions. The results suggest that mobile network providers’ attributes, satisfaction and perceived risk have significant impact on brand preference. Further, tweens´ choices are more likely to be affected by the choices of other people within their local (district) geographic area.

Introduction Many extant studies in the strategic management literature show that a firm’s network influences its innovation outcomes (Ahuja, Lampert, & Tandon, 2008). Networks are characterized by strong and weak ties in terms of the combination of the amount of time, intensity, intimacy, and reciprocal services (Granovetter, 1973). There is, however, a continuing debate about the relative advantages of strong and weak ties. These equivocal findings suggest that the relationship between tie strength and a firm’s innovation outcome is complex, and call for a more detailed examination of this relationship. The implications of networks for a firm’s innovation outcomes are quite significant. Nevertheless, the majority of research studies still examine networks using simple dyadic relationships (e.g., Capaldo, 2007). In reality, a firm’s networks are composed of more than a single dyadic relationship and are much more complex. Thus, dyadic approaches are limited in providing understanding of networks on a firm’s innovation performance. As such, we will take the perspective of a focal firm in a triad network. While still relatively simple, the triad network approach allows us to identify key relationships previously unexplored in network tie configuration, and to shed light on the equivocal results in the extant literature. Specifically, we will examine the position of the strong or weak ties among the firms, and also whether the strong or weak ties are adjacent or non-adjacent to the focal firm. Breakthrough innovation is defined as the basic invention, which leads to the evolution of many subsequent technological developments (Ahuja & Lambert, 2001). This definition suggests that novel and unique knowledge is required to create breakthrough innovation. Indeed, recent research shows that firms need novel knowledge created by network partners to create breakthrough innovation (e.g., Srivastava & Gnyawali, 2011). As such, we investigate how different levels of novel and diverse knowledge arising from the position of network ties impact a focal firm’s breakthrough innovation. Nevertheless, obtaining diverse and novel knowledge from networks does not guarantee the creation of successful breakthrough innovation. A firm needs a capability to learn, absorb and integrate the new knowledge into its works, which is its absorptive capacity. Thus, we examine the moderating role of a firm’s absorptive capacity on the relationship between the impact of the configurations arising from the position of strong/weak ties and a firm’s breakthrough innovation in a triad network relationship. Conceptual Framework We posit six different types of network configurations based on tie strength and position of strong/weak ties that are adjacent or non-adjacent to the focal firm in a triad (Figure 1). For example, Configuration 1 has three strong ties and Configuration 6 has three weak ties. Configuration 2 has two strong ties that are adjacent to a focal firm and one weak tie that is non-adjacent to a focal firm in a triad. Importantly, we use two theories (i.e., network theor and relational theory) to elaborate the impact of six configurations on a firm’s breakthrough innovation, considering the tie strength, the position of strong/weak ties, and whether the strong or weak ties are adjacent or non-adjacent to the focal firm. The first of these is network theory. Network theory and relational theory assert different effects of strong versus weak ties on a firm’s breakthrough innovation. To resolve the ambiguities in the literature on this issue, we combine network theory and relational theory and investigate the implication of the position of the strong or weak ties. We argue that the position of strong/weak ties must be considered to explain the impact of tie strength on firm breakthrough innovation in a triad context. For example, Configuration 2 has two strong ties adjacent to focal firm and one weak tie non-adjacent to focal firm (Figure 1). The non-adjacent weak tie provides potential for diverse and novel knowledge and reduced knowledge redundancy. Also, adjacent two strong ties provide the benefits of commitment and trust, and rich information flow. Additionally, these adjacent strong ties facilitate the transfer of novel knowledge generated from the non-adjacent weak tie. Thus, we argue that Configuration 2 has a potentially positive influence on firm breakthrough innovation. Configuration 5 has two adjacent weak ties and one non-adjacent strong tie. The non-adjacent strong tie has high knowledge redundancy and high trust and commitment between the two actors B and C (Figure 1). The non-adjacent strong tie between B and C induces potential opportunistic tendencies toward focal firm and inhibits information sharing with the focal firm. This indicates that the two firms form an alliance to the detriment of the focal firm. Further, adjacent weak ties provide novel and diverse information while maintaining less commitment and trust with the focal firm. Importantly, diverse information from adjacent weak ties is degraded because of the knowledge redundancy generated by non-adjacent strong tie between B and C. Thus, we argue that Configuration 5 has potentially negative influence on firm breakthrough innovation. The above discussion suggests that one cannot determine which type of network ties will tend create a firm’s breakthrough innovation simply by counting the numbers of weak and strong ties in the configurations. One must also consider the position of the strong and weak ties within the network and the focal firm’s absorptive capacity. For example, though there is a high level of knowledge redundancy created by the non-adjacent strong tie in Configuration 5, if the focal firm has strong ability to learn, the focal firm can still capture and use the limited new knowledge, depending on its absorptive capacity. Next, we explain how firm’s absorptive capacity influences the relationship between six configurations and breakthrough innovation. Methods We will collect a full sample of data from three main data sources: alliance data from the Securities Data Company (SDC) on Joint and Alliances, patent data from the National Bureau of Economic Research (NBER) U.S. Patent Citation 1997-2016, and financial data from COMPUSTAT. The initial sample will consist of all firms that announced a triad of strategic alliance firms across industries from 1997 to 2016 in the United States. Implications Our study makes two key contributions. First, we investigate the impact of various triad strong/weak tie network configurations on a firm’s breakthrough innovation. We test various effects accrued from the position of strong/weak ties that are adjacent or non-adjacent to a focal firm on the focal firm’s breakthrough innovation in the triad network. By examining these relationships, we uncover critical implications of the tie strength previously unexplored in the network literature. We provide conceptual advancement of Granovetter’s notion of the strength of weak ties, showing the importance of the position of strong or weak ties as a critical driver to influence a firm’s breakthrough innovation. Second, we investigate how a focal firm’s absorptive capacity moderates the impact of network configurations on a firm’s breakthrough innovation. This provides a more precise and fine-grained understanding of how a firm’s capability to absorb outside knowledge influences the relationship between network configurations and a focal firm’s breakthrough innovation. Combined, our two contributions help to resolve some of the equivocal results in the extant literature regarding the effects of strong or weak ties on breakthrough innovation.