본 연구에서는 유도가열기법을 활용한 콘크리트 촉진 발열양생 기술의 효율성을 평가하기 위하여 철근 배근 및 전도체 변수에 따른 유도가열에 의한 콘크리트 온도향상 성능 및 압축강도를 평가하였 다. 먼저 철근 자체의 유도가열 성능을 평가한 결과, 주철근 및 나선철근 모두 유도가열 직후 10분 이 내에 목표온도인 70℃에 도달하여 충분한 가열성능을 나타내었다. 주요변수로 나선철근의 유무, 나선 철근의 간격, 피복두께, 거푸집 종류, 시험체 크기의 변수를 고려하여 15시간의 유도가열 발열양생 후 압축강도 평가를 실시하였다. 평가 결과, 철근을 포함한 경우 유도가열 발열양생 효율이 약 20~85% 만큼 증가하였다. 또한 총 6종(강섬유, 비정질강섬유, 전기로슬래그, 탄소섬유, 탄소나노튜브, 흑연나노 섬유)의 전도성 재료를 선정하여 재료 자체의 유도가열을 통해 발열성능을 평가하였다. 평가결과 강섬 유, 비정질강섬유, 전기로슬래그는 1~7분 사이에 가열 목표온도인 70℃에 근접하게 도달하여 유도가 열에 의한 콘크리트 발열성능을 향상 시킬 수 있는 혼입재료로 최종 선정하였다. 이상의 3가지 전도체 를 혼입하여 콘크리트를 타설한 뒤 15시간 유도가열 후의 압축강도를 평가한 결과, 강섬유 1%를 혼 입한 경우 발열양생을 실시하지 않은 상온양생에 비하여 강도가 186% 증가하였고, 잔골재의 50%를 전기로 슬래그로 치환한 경우 발열양생을 실시하지 않은 상온양생에 비하여 강도가 187% 상승하였다.

The spectrum of this study was research on the closed hydroponic cultivation of netted melons (Cucumis melo L.) using coir substrate, analyzing the impact of this cultivation method on melon yield, fruit quality, and the efficiency of water and nutrient usage. The experimental results showed that the average fruit weight of the melons grown in a closed system was 71.4 g higher than that of the open system, and the fruit width was on average 0.2 cm larger, showing a statistically significant difference. However, there was no difference in the average sugar content of the fruit flesh and height. Although there is no substantial commercial difference, it is conjectured that the change in the macronutrients ratio in the irrigation has played a role in the statistically significant increase in fruit weight, which is attributed to changes in the crops' nutrient uptake concentrations. This necessitates further research for a more comprehensive understanding. In terms of the productivity of irrigation required to produce the fruit, applying the closed system resulted in an increase of 7.6 kg/ton compared to the open system, saving 31.6% of water resources. Additionally, in terms of nutrients, cultivating in a closed system allowed for savings of approximately 59, 25, 55, 83, 76, and 87% of N, P, K, Ca, Mg, and S, respectively, throughout the entire cultivation period. As the drainage was reused, the ratios of NO3 - and Ca2+ increased up to a maximum of 9.6 and 9.1%, respectively, while the ratios of other ions gradually decreased. In summary, these results suggest that closed hydroponic cultivation can effectively optimize the use of water and fertilizer while maintaining excellent fruit quality in melon cultivation.

PURPOSES : This study analyzes the estimated traffic volumes on roads and railways based on econometrics. METHODS : The accuracy of traffic forecasting was analyzed based on the average difference between predicted and actual values. This study distinguishes itself from existing literature by conducting a comparative analysis categorized by project type. In this study, econometric analyses, including bias and efficiency evaluation, were conducted for 308 projects in Korea. RESULTS : We conducted econometric analysis by dividing the data into project types. This study examines the accuracy of estimates in South Korea's road and railway projects concerning various factors, including project types (mobility-focused or accessibility-focused), implementing agencies, and the performance of preliminary feasibility studies. Notably, it identifies a tendency for overestimation, particularly in railway projects and mobility-focused road projects, such as expressways and national highways, as well as in projects executed by local governments. The mean percentage error (MPE) for the analyzed projects was -46.62%, indicating a significant overestimation bias with resulting inefficiencies. However, our analysis revealed that road projects, particularly those accompanied by preliminary feasibility studies and implemented by the central government, exhibited reduced bias and improved efficiency. The presence or absence of preliminary feasibility studies significantly influenced estimation bias. Interestingly, even when preliminary feasibility studies are conducted, the choice of the implementing agency remains a crucial factor affecting estimation bias. In addition, railway projects continue to demonstrate a notable overestimation bias, warranting further attention. CONCLUSIONS : Considering bias, efficiency, and MPE is advisable when forecasting traffic.

PURPOSES : This study aims to analyze the efficiency of the safety and management of private highways. METHODS : Variables were selected based on the data and performance related to the safety of 18 private highways. The appropriateness of operations management was reviewed using Data Envelopment Analysis (DEA) analysis. Items with a scope for improvement were reviewed and adjustment measures were presented. RESULTS : To increase safety management efficiency, the degree of reduction in personnel and operating expenses was presented based on the relative efficiency group. CONCLUSIONS : It is necessary to adjust the appropriate management organization and operating costs according to the characteristics of each route. Moreover, the limitations of the study and possible improvements were presented.

지방관리 무역항은 비교적 중소형 무역항으로 지방도시의 경제력 강화 및 지역 산업 부가가치 제고를 위해 활발한 운영이 필요 하다. 또한, 선박대형화가 이루어지고 있는 국제적 흐름에서 지방관리 무역항의 효율성 증대를 위해 항만기본계획상 기존 선석규모 대비 대형선박의 접안이 필요하며, 부두 및 선박의 안전성 확보를 위해 대형선박 접안시 계류시설 확충 및 안전운용기준 마련이 필요하다. 본 연구에서는 지방관리 무역항 중 옥계항을 선정하여, 현행 2만 DWT급 부두에 5만 DWT급 선박이 계류시 시나리오에 따른 계류안전성 평 가를 수행하였다. 평가 결과, 대상 부두에 100톤급 계선주를 신설하였을 경우, 긴급이안기준은 기존 파주기 3.2초에서 풍속 27노트, 파주기 5.0초에서 풍속 22노트의 계류 한계 조건이 파주기 3.2초에서 풍속 41노트, 파주기 5.0초에서 풍속 36노트로 약 50 % 정도 증가하는 것으로 분석되었다. 본 연구 결과는 지방관리 무역항에 기존 선석규모 대비 대형선박 접안시 부두 계류시설의 안전성 강화와 안전운용기준 설정 을 위한 기초 자료로 활용될 수 있다.

This study set up the estimates of leakage management efficiency evaluation and leakage management goal that could be used in local water distribution networks efficiency business and modernization business. The data were analyzed using data envelopment analysis and multiple regression analysis. To this end, with leakage management input indices concerning leakage reduction activities (e.g., aged pipe replacement, water meter replacement, leakage restoration, and leakage detection) and leakage management calculation indices (e.g., the increase of revenue water ratio and the reduction of leakage ratio), the data on 22 K-water consignment local water supply systems were analyzed for the years from 2004 through 2018. Using the results of efficiency analysis by data envelopment analysis, the other DMUs (Decision Making Unit) benchmarked the DMU with the highest efficiency to maximize the leakage management efficiency for all DMUs. Through this, leakage management goal estimates were drawn with the input indices of four leakage reduction activities and calculation indices of the increase of revenue water ratio and the reduction of leakage ratio by multiple regression analysis for each group based on the revenue water ratio and leakage ratio. The correlation coefficients of the leakage management goal estimate for the criteria for the revenue water ratio amounted to 0.553 and 0.771. The correlation coefficients of the leakage management goal estimate for the criteria for leakage ratio were 0.397 and 0.865. Accordingly, we estimated the quantity and priority of four leakage reduction activities for the target leakage ratio and revenue water ratio.

도시공원은 시민의 여가 공간으로 시민들이 공원을 방문하는 정도는 공원이 제공하는 사회적 효용을 측정하는 유용한 지표로 활용될 수 있다. 본 연구는 도시공원의 입지적 특성을 바탕으로 시민들이 도시공원을 방문하는 정도를 평가하는 방문 잠재력 지수를 제안한다. 방문 잠재력 지수는 도시공원 입지의 공간적 효율성과 형평성을 동시에 고려하여 공간 접근성과 기회 대체성을 결합하고 있다. 도시공원의 공간 접근성은 공원의 서비스 권역 내에 거주하는 인구 분포로 측정했으며, 도시공원의 기회 대체성은 인접 공원의 이용 가능성으로 측정하였다. 도시공원의 공간 접근성과 기회 대체성은 각각 수요와 공급 정도를 나타내는 개념으로 이를 결합한 방문 잠재력 지수는 공원의 공급 필요성이 큰 입지를 효과적으로 보여줄 수 있다. 사례 분석으로 도시공원 일몰제로 사회적 관심의 대상이 되고 있는 서울시 도시자연공원구역의 방문 잠재력을 실증적으로 평가하였다. 본 연구에 서 제안하는 도시공원 방문 잠재력 지수는 도시공원의 입지적 가치를 다각도에서 포착하고 유연한 평가 방식을 제공함으로써 기존 입지와 신규 후보 입지 모두를 평가하는데 유용하게 쓰일 수 있을 것으로 기대된다

Evaluating the operational efficiency of electric vehicle charging stations (EVCSs) is important to understand charging network evolution and the charging behavior of electric vehicle users. However, aggregation of efficiency performance metrics poses a significant challenge to practitioners and researchers. In general, the operational efficiency of EVCSs can be measured as a complicated function of various factors with multiple criteria. Such a complex aspect of managing EVCSs becomes one of the challenging issues to measure their operational efficiency. Considering the difficulty in the efficiency measurement, this paper suggests a way to measure the operational efficiency of EVCSs based on data envelopment analysis (DEA). The DEA model is formulated as constant returns of output-oriented model with five types of inputs, four of them are the numbers of floating population and nearby charging stations, distance of nearby charging stations and traffic volume as desirable inputs and the other is the traffic speed in congestion as undesirable one. Meanwhile, the output is given by the charging frequency of EVCSs in a day. Using real-world data obtained from reliable sources, we suggest operational efficiencies of EVCSs in Seoul and discuss implications on the development of electric vehicle charging network. The result of efficiency measurement shows that most of EVCSs in Seoul are inefficient, while some districts (Nowon-gu, Dongdaemun-gu, Dongjak-gu, Songpa-gu, Guro-gu) have relatively more efficient EVCSs than the others.

PURPOSES : This study aims to investigate the effect of the propagation time of variable message sign (VMS) information and drivers’ detour rate on the VMS performance under non-recurrent traffic states. METHODS: A microscopic simulation model (i.e., VISSIM and VISSIM COM User Interface) was developed at a location where VMS messages were most frequently displaced in 2018 from the Busan Regional Construction and Management Administration. The non-recurrent traffic states realized in this study were one- and two-lane close cases with scenarios involving multiple propagation times from 0 min to 20 min in 2 min increments and detour rates from 0% to 50%, in 10% increments. The measures of effectiveness are the average delay per vehicle, total travel time, and reduction rate of the total travel time based on the average value of 30 multiple simulation runs for individual scenarios. RESULTS:For the one- and two-lane close cases, the reduction rate of the total travel time increased as the propagation time shortened and the detour rate became bigger. The optimal (i.e., 0 min propagation time and 50% detour rate) and worst (i.e., 20 min propagation time and 10% detour rate) scenarios produced 41.1% (8.9 h) and 6.4% (1.4 h) and 26.4% (86.5 h) and 1.4% (4.7 h) of the total travel time for the one- and twolane close cases, respectively. CONCLUSIONS : The study results implied that the late propagation time and the low detour rate might not significantly influence the VMS system. Therefore, it is important to improve the information process time for the shorter propagation time and the reliability of the VMS information for a higher detour rate, which will result in a better VMS system performance.

PURPOSES: This study evaluates the efficiency of snow removal operation resources using data envelopment analysis (DEA). The results of this study can help decision-making strategies, especially for resource allocation for snow removal works on national highways. METHODS: First, regional road management offices (DMUs) for efficiency evaluation were set up, and a database (for years 2012-2016) for analysis was formed. Second, DEA was carried out by selecting input and output variables based on the constructed database. Lastly, based on the results of the DEA, the efficiency of each regional road management office was evaluated. In addition, the potential for future improvement was determined. RESULTS: The results showed that there was a large variation in efficiency of snow removal operation resources by regional offices. CONCLUSIONS: The results of this study imply that the evaluation of efficiency for snow removal operation resources is important when decisions related to snow-removal strategies are made by road management offices.

2014년, 금융위원회는 기술신용평가기관(TCB, Tech Credit Bureaus)을 지정 하여 기술신용평가서를 발급하게 하였고 현재까지 5개의 기술신용평가기관과 금융위원회 권고, 레벨 4에 진입한 KEB하나은행, 국민은행, 우리은행, 신한은행 등에서 기술신용평가서 를 발급하고 있다. 한편, KEB하나은행의 기술평가모델은 25개의 세부평가항목으로 구성되 어 있으며, 이러한 항목등급이 가중 결합되어 기술등급이 산출, 기술등급은 신용등급과 결 합하여 최종적으로 기술신용등급이 산출된다. 본 연구에서는 KEB하나은행에서 2016년 하 반기에 자체발급한 406건의 기술평가결과를 분석하였으며, 경영주 동업종 근무년수, 기술개 발전담부서 보유여부, 기술인력, 연구개발투자금액, 인증수, 특허수를 기반으로 지표간의 상 관분석 및 기술등급과의 영향력을 분석하였다. 분석결과에 의하면, 기술개발전담부서, 특허 수, 연구개발투자금액 등의 정량적지표가 기업 기술등급에 상당한 영향을 끼치는 것으로 나타났으며, 특히, 기술개발전담부서 보유여부는 기술등급과 가장 높은 상관관계를 나타내고 있음을 나타냈다.

본 연구는 연안여객선사의 안전관리 운영 효율성을 분석하기 위한 기초연구로 적절한 안전경영지표 평가항목을 설계하고 연안여객선 사를 대상으로 평가항목의 유효성을 검증하는데 목적이 있다. 이를 위해 먼저 연안여객운송사업자의 안전관리책임자, 공무원(선박검사관), 여객 선 운항관리자 등으로 구성된 전문가 그룹을 통해 연안여객선사의 자발적 안전관리 활동을 평가하기 위한 5개의 평가항목과 14개의 세부 평가요 인을 선정하고 사전검증 및 테스트를 통해 객관성을 제고하였다. 이 안전경영지표 평가항목을 이용하여 44개 연안여객선사에 대한 자발적 안전 관리 수준을 평가하였다. 그리고 평가항목의 유효성을 검증하기 위하여 안전경영지표 평가항목 결과와 중대해양사고 비율을 비교분석하여 평가 항목의 타당성을 확인하였다. 이를 통해 자발적 안전경영 수준이 높은 업체일수록 중대해양사고가 발생하지 않고 자발적 안전관리에 무관심하거 나 소홀한 업체는 상대적으로 높은 중대해양사고가 발생하고 있는 것을 알 수 있었다. 이처럼 안전경영지표 평가항목 선정을 통해 연안여객선사 의 안전관리 운영 효율성을 분석하는데 중요한 항목을 객관적인 관점에서 도출하였다. 따라서 향후 안전관리 효율성 분석을 위한 기초자료로 활 용될 수 있을 것이다.

This paper was to evaluate social enterprises’ management efficiency with Data Envelope Analysis (DEA). The data was based on the 168 social enterprises’ of annual performance reports published in 2015. The research focused on to measure both financial efficiency and social impact of the companies simultaneously. To apply DEA, the paper classified the enterprises into seven types based on types of socal impacts which each company provides before the estimation of the efficiency. The research results showed that group D, which employes disadvantaged people, provides social services and shares resources was the most efficient group and had higest net worths in Pure Technical Efficiency. In contrast, Group B, which only employs social advantage people and provides social service, was the least efficient one. The research suggests a practical and efficient framework in measuring social enterprises’ management efficiency, including both the financial performance and social impacts simultaneously with their self-publishing reports. Because the Korea Social Enterprise Promotion Agency does not open business reports which social enterprises submit each year, there are basic limitations on researchers attempting to analyse with data from all social enterprises in Korea. Thus, this study dealt with only 10% of the social enterprises which self-published their performance report on the Korea Social Enterprise Promotion Agency’s web site. Regardless of these limitations, this study suggested substantial methods to estimate management efficiency with the self-published reports. Because self-publishing is increasing each year, it will be the main source of information for researchers in examining and evaluating social enterprises’ financial performance or social contribution. The research suggests a practical and efficient framework in measuring social enterprises’ management efficiency, including both the financial performance and social impacts simultaneously with their self-publishing reports. The research results suggest not only list of efficient enterprises but also methods of improvement for less efficient enterprises.