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        검색결과 1,248

        1.
        2024.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this study, the existence of an optimal pattern among transition methods applied during changes in traffic signal timing was investigated. We aimed to develop this pattern into an artificial intelligence reinforcement-learning model to assess its effectiveness METHODS : By developing various traffic signal transition scenarios and considering 19 different traffic signal transition situations that can be applied to these scenarios, a simulation analysis was performed to identify patterns through statistical analysis. Subsequently, a reinforcement-learning model was developed to select an optimal transition time model suitable for various traffic conditions. This model was then tested by simulating a virtual experimental center environment and conducting performance comparison evaluations on a daily basis. RESULTS : The results indicated that when the change in the traffic signal cycle length was less than 50% in the negative direction, the subtraction method was efficient. In cases where the transition was less than 15% in the positive direction, the proposed center method for traffic signal transition was found to be advantageous. By applying the proposed optimal transition model selection, we observed that the transition time decreased by approximately 70%. CONCLUSIONS : The findings of this study provide guidance for the next level of traffic signal transitions. The importance of traffic signal transition will increase in future AI-based traffic signal control methods, requiring ongoing research in this field.
        4,000원
        2.
        2024.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this study, the factors affecting commuting time according to city, county, and ward were empirically analyzed. METHODS : We estimated the average commuting time according to city, county, and ward by controlling for the characteristics of individual commuters, using a 2% sample of the Population and Housing Census of the National Statistical Office, and performed a twostage regression analysis using the average commuting time as the dependent variable. RESULTS : Among the regional attributes in the second stage, the share of commuters with different work and living areas was analyzed as a representative factor causing longer commuting times. The proportion of each mode of transportation in the total regional traffic volume and the population and household characteristics were also analyzed as affecting the average commuting time in the region. Particularly, when analyzing regions by dividing them into cities and counties within a metropolitan city and cities and counties within a province, or by dividing them into urban and rural areas, it can be observed that the factors affecting the average commuting time in the region are different, indicating that differentiated transportation policies are required according to the characteristics of the region. CONCLUSIONS : Commuting time entails increasing opportunity costs as wages increase. However, the expansion of the inter-regional transportation infrastructure acts as a factor in increasing job-residence separation and causes contradictory results by increasing the commuting time. If the characteristics of each region are different, and a function hierarchy as a city appears, travel between regions will become more common. Today, the widening gap between urban and rural areas in terms of employment and residential conditions can cause social waste due to increased commuting times. Ultimately, the extinction crisis of rural areas can be alleviated through policy by encouraging proximity to direct employment through the balanced development of jobs and settlement conditions between regions.
        4,200원
        4.
        2024.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study aims to improve pedestrian safety by analyzing the effectiveness of displaying the remaining time of red crosswalk signal that provide pedestrians with information regarding the time available for crossing METHODS : This study analyzes the effectiveness of newly installed displays for remaining time of the red pedestrian signal in the cities of Yeongcheon and Yeongju in Gyeongsangbuk-do. The data collection was divided into periods before and after the installation of the facilities. Pedestrian departure delays were measured at the introduction and subsequent stages of installation, and changes in pedestrian behavior were quantitatively analyzed. Statistical significance of the results was verified using a t-test. RESULTS : For the displays of remaining time of crosswalk red signals installed in Yeongju, the pedestrian departure loss time decreased from 3.36 seconds before installation to 1.85 seconds after installation. Additionally, compared to the pre-installation situation, the postinstallation situation showed a relatively lower standard deviation, indicating that the pedestrians exhibited a more consistent pattern when starting to cross. Similarly, for the displays of remaining time of crosswalk red signal installed in Yeongcheon, the pedestrian departure loss time decreased from 2.37 seconds before installation to 1.89 seconds after installation. As in Yeongju, the post-installation situation showed a relatively lower standard deviation, indicating that the pedestrians exhibited a more consistent pattern when starting to cross. CONCLUSIONS : In this study, we verified the effect of newly installed pedestrian countdown signals on improving pedestrian safety at two intersections in Yeongcheon and Yeongju, which were selected through a survey of traffic accident-prone areas in Gyeongsangbuk-do. Pedestrian countdown signals were quantitatively confirmed to have a positive impact on pedestrian safety. Based on the observations, it is anticipated that expanding the installation of these signals will have a positive effect on pedestrian safety, particularly in areas with frequent traffic accidents and the senior and children protection zones. Results of this study indicate that the proposed policy measures are expected to strengthen pedestrian safety and reduce traffic accidents.
        4,000원
        5.
        2024.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        거저리는 식품으로 사용되기 때문에 유충기가 오래 지속되면 더 좋다. 반면에 거저리의 개체수 유지를 위 해 성장을 가속화하기 위해서는 유충이 빨리 성충이 되면 더 좋다. 이 연구에서는 개체군 밀도가 거저리의 발달 시 간에 미치는 영향을 구명하였다. 이를 위해 상단 7 cm, 하단 5 cm, 높이 3 cm 크기의 용기를 사용했다. 거저리는 용기 당 1, 2, 5, 10, 20마리의 밀도로 용기에서 서식하였다. 용기에 밀기울 1 g을 넣고 거저리의 먹이 여부에 따라 라벨을 붙였다. 실험은 세 번 반복되었다. 모든 실험에서 개체군 밀도가 높을수록 유충에서 번데기로의 변환 시간이 짧았 지만 번데기에서 성충으로 변환되는 시간은 크게 다르지 않았다. 또한 먹이가 있는 그룹에서 번데기로의 변환 시간 이 단축되었지만, 성충으로 변환되는 시간에는 차이가 없었다. 이 연구 결과는 유충기를 연장하기 위해 더 낮은 밀 도가 필요하고 더 빠른 속도로 성충이 필요하다면 밀도가 더 높아야 한다는 것을 보여주었다. 결론적으로 거저리의 발달 시간은 개체수 밀도에 의해 제어할 수 있을 것이다.
        4,000원
        6.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study presents a general guideline for the initial management of traffic signal timings in response to traffic incidents, prior to the implementation of specific treatments in detail. The proposed solution includes a set of optimal reductions in the green time rates at three signalized intersections upstream. METHODS : To account for the various traffic and incident conditions that may be encountered, a total of 36 traffic-condition scenarios were prepared. These scenarios encompass a wide range of conditions, from unsaturated to near-saturated conditions, and were designed to provide a comprehensive understanding of the impact of traffic conditions on signal timing. For each of the traffic conditions, all 27 traffic signal timing combinations were subjected to testing. A total of 972 simulation analyses were conducted using the SUMO model. The results indicated that the scenario with the lowest control delay was the optimal choice. RESULTS : The results indicated that the most effective initial management for the traffic incident would be to reduce the green signal timings by 20% at the first two upstream intersections and by 40% at the third intersection. CONCLUSIONS : We propose reducing the green times by 20% at the first and second intersections and by 40% at the third intersection as the initial response of the traffic signal control center when a traffic incident occurs.
        4,000원
        7.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적: 본 연구는‘2019년 생활시간조사’자료를 활용하여 작업치료 실행체계(Occupational Therapy Practice Frame; OTPF) 4판의 9가지 작업에 따라 독거노인과 비독거노인의 일상적 시간사용의 차이를 작업균형의 관점에서 알아보고자 한다. 연구방법: 통계청에서 추출한 자료를 기반으로 65세 이상 노인 자료를 독거노인과 비독거노인으로 분류하였다. 활동분류체계를 OTPF에 따라 재분류하고, 자료분석은 SPSS 29.0을 사용하였다. 결과: 활동유형 시간 사용에 따른 교차분석 결과 독거노인은 저활동에 속할 확률이 높았고, 비독거노인은 과활동에 속할 가능성이 높았다. 작업별 시간 사용에서는 독거노인은 비독거노인에 비해 일상생활, 일에 더 적은 시간을 사용한다. 결론: 독거노인들의 건강한 노년기를 위해서는 본 연구 결과를 노인들의 작업균형을 위한 중재에 활용하여야 할 것이다.
        4,200원
        8.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study aims to calculate the estimation of travel time saving benefits from smart expressway construction by considering the willingness to pay for automated vehicles. METHODS : In this study, data were collected from 809 individual drivers through a stated preference survey. A multinomial logit model was constructed to analyze the choice behavior between arterial roads, expressways, and smart expressways. Through this, the values of time and benefits were estimated. RESULTS : The value of time was calculated at 19,379 won per vehicle per hour for arterial roads and expressways and 23,061 won per vehicle per hour for smart expressways. Applying these values to the Jungbu Naeryuk expressway, we evaluated the demand change and benefits resulting from the improvement to the smart expressways. The results show that the traffic volume on the Jungbu Naeryuk expressway is expected to increase by 4.7% to 20.7% depending on the changes in capacity. CONCLUSIONS : The travel time saving benefits are estimated as positive, resulting from the construction of smart expressways. The benefits resulting from the construction of new smart expressways are expected to be enhanced due to the anticipation of more significant time-saving effects.
        4,000원
        9.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적: 본 연구는 인간작업 모델을 기반으로 한 여가활동이 지역사회 거주 장애인의 삶의 질, 자기효능감, 시간 사용에 미치는 영향을 알아보고자 하였다. 연구방법: 본 연구는 보건소 지역사회 재활 사업에 참여하는 지역사회 거주 장애인 15명을 선정하여 대상으로 했다. 대상자와 작업치료 학부생 봉사자 2~3명을 매칭하였고, 지역사회 재활 담당 작업치료사와 작업치료학과 교수의 지도하에 평가와 중재를 제공하였다. 연구설계는 단일집단 사전⋅사후 설계를 적용했다. 중재는 10주 동안 10회기 실시하였으며 중재 전⋅후를 비교하기 위해 삶의 질 평가를 위해 한국판 WHO 삶의 질 척도-단축형(Korean Version of The World Health Organization Quality of Life Brief Version), 자기효능감 평가를 위해 일반적 자기효능감 척도(General Self-efficacy Scale), 시간 사용 평가를 위해 작업 질문지(Occupational Questionnaire; OQ)를 사용하였다. 결과: 10주간의 인간 작업모델을 기반으로 한 여가활동을 통해 지역사회 거주 장애인의 삶의 질은 전반적 삶의 질, 신체적 건강, 사회적 관계에서 상승을 보였다. 자기효능감은 유의한 변화를 보이지 않았다. 시간사용은 OQ의 전 문항에서 유의하게 변화가 있었다. 결론: 지역사회 거주 장애인이 삶에서 원하는 여가활동을 할 수 있도록 많은 방문재활이 이루어지기를 기대한다.
        4,200원
        10.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Vertical takeoff and landing (VTOL) is a core feature of unmanned aerial vehicles (UAVs), which are commonly referred to as drones. In emerging smart logistics, drones are expected to play an increasingly important role as mobile platforms. Therefore, research on last-mile delivery using drones is on the rise. There is a growing trend toward providing drone delivery services, particularly among retailers that handle small and lightweight items. However, there is still a lack of research on a structural definition of the VTOL drone flight model for multi-point delivery service. This paper describes a VTOL drone flight route structure for a multi-drone delivery service using rotary-wing type VTOL drones. First, we briefly explore the factors to be considered when providing drone delivery services. Second, a VTOL drone flight route model is introduced using the idea of the nested graph. Based on the proposed model, we describe various time-related attributes for delivery services using drones and present corresponding calculation methods. Additionally, as an application of the drone route model and the time attributes, we comprehensively describe a simple example of the multi-drone delivery for first-come-first-served (FCFS) services.
        4,600원
        14.
        2024.04 구독 인증기관·개인회원 무료
        Regulatory Guide (RG) 1.60 presents the response spectra for the seismic design, especially for the safe shutdown earthquake (SSE), of nuclear power plants. This guide is applicable to a two-step process involving the issuance of construction permits and operating licenses (10 CFR Part 50) as well as the issuance of combined construction and operating licenses (COLs), early site permits (ESPs), and standard plant design certifications (10 CFR Part 52) [1]. New reactor designs, however, require modified design response spectra (MDRS) by broadening the high-frequency range from design response spectra (DRS) in RG 1.60. In order to generate artificial time histories to meet the acceptable criteria described in NUREG-0800 [2], it9s necessary to develop the power spectral density of the MDRS. In this paper, we generate the artificial earthquake time histories of the MDRS for further research.
        15.
        2024.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Geopolymer, also known as alkali aluminum silicate, is used as a substitute for Portland cement, and it is also used as a binder because of its good adhesive properties and heat resistance. Since Davidovits developed Geopolymer matrix composites (GMCs) based on the binder properties of geopolymer, they have been utilized as flame exhaust ducts and aircraft fire protection materials. Geopolymer structures are formed through hydrolysis and dehydration reactions, and their physical properties can be influenced by reaction conditions such as concentration, reaction time, and temperature. The aim of this study is to examine the effects of silica size and aging time on the mechanical properties of composites. Commercial water glass and kaolin were used to synthesize geopolymers, and two types of silica powder were added to increase the silicon content. Using carbon fiber mats, a fiber-reinforced composite material was fabricated using the hand lay-up method. Spectroscopy was used to confirm polymerization, aging effects, and heat treatment, and composite materials were used to measure flexural strength. As a result, it was confirmed that the longer time aging and use of nano-sized silica particles were helpful in improving the mechanical properties of the geopolymer matrix composite.
        4,000원
        16.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적: 본 연구는 초등학생의 부모애착과 시간사용 만족도가 학교적응에 미치는 영향을 알아보고자 하였다. 연구방법: 한국아동패널연구의 12차(2019년) 패널에 응답한 1,172명의 데이터를 추출하여 부모애착, 시간사용 만족도, 학교적응 항목을 분석하였다. 자료는 기술통계, 독립표본 t-검정, 상관분석, 위계적 다중회귀분석을 실시하여 분석하였다. 결과: 연구 결과 초등학생의 학교적응에 부모와의 의사소통과 신뢰감, 시간사용 만족감은 양의 상관관계를 부모에게서 느끼는 소외감은 음의 상관관계가 있음을 확인하였으며, 부모애착과 시간사용 만족감은 학교적응에 25%의 영향력이 있음을 확인하였다. 결론: 초등학생의 학교적응 향상을 위하여 부모는 초등학생 아동과 시간을 질적으로 보낼 필요가 있으며, 이를 위한 공적 지지나 환경의 변화 역시 필요할 것으로 사료된다.
        4,200원
        17.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        전 세계적으로 급격하게 성장하는 스마트농업의 중요 요소 중 하나인 자동 관개시스템은 토양수분 센서에서 계측한 데이터를 기반으로 관개시점과 관개량을 판단하기 때문에 토양수분 센서의 설치가 필수적이다. 하지만 국내의 경우 토양을 고려하지 않고 단순히 포장의 가운데에 센서를 설치하는 등 토양수분 센서의 설치 위치에 대한 기준이 마련되어 있지 않아 토양수분 계측 위치에 관한 기준 검토가 필요하다. 본 연구에서 통계학적 방법을 이용하여 토양수분의 대표 계측지점을 선정 연구를 수행하였다. 토양은 수직적 또는 수평적으로 불균일성을 갖기에 구명이 쉽지 않다. 따라서 포장 전체에 걸쳐 지속해서 편향이 발생하지만 특정 위치에서의 평균 토양수분이 시간에 따라 유지한다는 시간 안정성 개념을 기반으로, 평균 토양수분을 나타내는 대표지점 선정 연구를 수행하였다. 토양수분을 측정하기 위한 시스템을 제작하였고, TDR (Time Domain Reflectometry) 센서를 이용하여 총 30개 지점을 측정하였다. 2023년 5월부터 8월까지 측정한 날짜·지점별 데이터를 이용하여, 지점의 편향을 정량화하여 식별할 수 있는 MRD (Mean Relative Difference, 평균상대차이)와 측정의 정밀도를 나타내는 RD (Relative Difference, 상대차이)의 SDRD (Standard Deviation of Relative Difference, 표준편차)를 산출하고, MRD와 SDRD를 통합한 지표로써 RMSE (Root Mean Square Error, 평균제곱근오차) 를 구하여, 시간 안정성이 가장 높은 지점인 RMSE의 수치가 최소인 지점을 대표지점으로 선정하였다. 토양수분 센서로 측정한 데이터를 사용하여 지점별 RMSE를 산출하고 비교하여, 평균적인 토양수분을 나타내는 대표지점을 선정할 수 있음을 확인하였다.
        4,000원
        18.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study aimed to identify factors affecting the duration of traffic incidents in tunnel sections, as accidents in tunnels tend to cause more congestion than those on main roads. Survival analysis and a Cox proportional hazards model were used to analyze the determinants of incident clearance times. METHODS : Tunnel traffic accidents were categorized into tunnel access sections versus inner tunnel sections according to the point of occurrence. The factors affecting duration were compared between main road and tunnel locations. The Cox model was applied to quantify the effects of various factors on incident duration time by location. RESULTS : Key factors influencing mainline incident duration included collision type, driver behavior and gender, number of vehicles involved, number of accidents, and post-collision vehicle status. In tunnels, the primary factors identified were collision type, driver behavior, single vs multi-vehicle involvement, and vehicles stopping in the tunnel after collisions. Incidents lasted longest when vehicles stopped at tunnel entrances and exits. In addition, we hypothesize that incident duration in tunnels is longer than in main roads due to the reduced space for vehicle handling. CONCLUSIONS : These results can inform the development of future incident management strategies and congestion mitigation for tunnels and underpasses. The Cox model provided new insights into the determinants of incident duration times in constrained tunnel environments compared to open main roads.
        4,000원
        20.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Gastrodia elata has been used in traditional Chinese medicine for treating headaches, dizziness, and convulsive illness for centuries. G. elata has traditionally been processed by steaming or blanching to increase the content and quality of its main ingredients. This study aimed to identify changes in physicochemical properties and active ingredients of G. elata depending on the steaming time. Data of this study could be used to develop traditional medicine and health foods. No steaming was used as a control. Steaming time was 5, 10, 20, 30, 60, or 120 min. The drying yield according to the steaming time ranged from 20.2% to 22.9%, with the lowest drying yield at 120 min. As the steaming time increased, gastrodin content increased more than that in fresh G. elata due to inhibition of β-glucosidase enzyme activity, 4-hydroxybenzyl alcohol condensation, and parishin decomposition. Steamed G. elata did not show higher total polyphenols, total flavonoids, or ABTS radical scavenging activities than fresh G. elata even with an increase of steaming time. The steaming time to improve the quality of G. elata may varied depending on the size of G. elata. Thus, it is important to set the steaming time taking these characteristics into consideration.
        4,000원
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