• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1251-1260
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• 2013

This paper presents the optimal scheduling of hourly consumption in a residential community (community, neighborhood, etc.) based on real-time electricity price. The residential community encompasses individual residential loads, communal (shared) loads, and local generation. Community-aggregated loads, which include residential and communal loads, are modeled as fixed, adjustable, shiftable, and storage loads. The objective of the optimal load scheduling problem is to minimize the community-aggregated electricity payment considering the convenience of individual residents and hourly community load characteristics. Limitations are included on the hourly utility load (defined as community-aggregated load minus the local generation) that is imported from the utility grid. Lagrangian relaxation (LR) is applied to decouple the utility constraint and provide tractable subproblems. The decomposed subproblems are formulated as mixed-integer programming (MIP) problems. The proposed model would be used by community master controllers to optimize the utility load schedule and minimize the community-aggregated electricity payment. Illustrative optimal load scheduling examples of a single resident as well as an aggregated community including 200 residents are presented to show the efficiency of the proposed method based on real-time electricity price.

• 동아시아경상학회지
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• 제8권1호
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• pp.1-19
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• 2020

Purpose - This study is to classify quality characteristics of online environment-friendly agricultural products shopping malls into 6 categories and to empirically test their relationship with customer trust, perceived manageability, perceived utility and purchase intention. Research design, data, and methodology - This study targeted adults who have purchased ecofriendly agricultural production online malls for 4 weeks from September 3 to September 30, 2019. The survey type used was a structuralized self-report survey questionnaire made to meet the research purpose in 2019 as the time range. Out of 800 questionnaires, 500 copies are used after excluding surveys with insincere responses. Results - First, results to hypothesis 1, which was about independent variables and customer trust. Analysis showed that health, familiarity, platform reputation, reviews and product quality were found to have significant effect on customer trust; the hypothesis was adopted. On the other hand, system security did not affect customer trust significantly; it was rejected. Second, customer trust was shown to have significant effect on perceived manageability and perceived utility, so the hypothesis was adopted. Third, the hypothesis that perceived manageability moves onto perceived utility was adopted. Moreover, the hypothesis that perceived manageability moves onto purchase intention and the hypothesis that perceived utility moves onto purchase intention were adopted as well. Conclusions - Furthermore, the results of the study imply that it's imperative for online environment-friendly agricultural products shopping malls to consider their characteristics as the means to increase purchase intention of customers.

• The Journal of Asian Finance, Economics and Business
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• 제8권7호
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• pp.91-101
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• 2021

The paper examines the impact of the COVID-19 pandemic on the stock market prices. The vector autoregression model (VAR) has been used in this analysis to survey 341 stocks on the Ho Chi Minh City Stock Exchange (HOSE) for the period from January 23, 2020 to December 31, 2020. The empirical results obtained from the analysis of 11 economic sectors suggest that there is a statistically significant impact relationship between COVID-19 and the healthcare and utility industries. Additional findings show a statistically significant negative impact of COVID-19 on the utility share price at lag 1. Analysis of impulse response function (IRF) and forecast error variance decomposition (FEVD) show an inverse reaction of utility stock prices to the impact of COVID-19 and a gradual disappearing shock after two steps. Major findings show that there is a clear negative effect of the COVID-19 pandemic on share prices, and the daily increase in the number of confirmed cases, indicate that, in future disease outbreaks, early containment measures and positive responses are necessary conditions for governments and nations to protect stock markets from excessive depreciation. Utility stocks are among the most severely impacted shares on financial exchanges during a pandemic due to the high risk of immediate or irreversible closure of manufacturing lines and poor demand for basic amenities.

• 한국항만학회지
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• 제9권1호
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• pp.33-43
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• 1995

Korean economic and industrial structure has been seperated into some areas with the trend of the change to the bloc system of international economy: the Gyeongin including the capital area, the Middle-West, the South-West, the South-East, and the Eastern sea areas. Mokpo port has played a major role as the central one of the South-West area and the entrance of Yeong-san river of Jeonnam province gate. Some studies has been done on the Mokpo port, but there is no research of the analytical approach about it. In this paper, we analyze the data of 1994's on the domestic and oceangoing piers in the Mokpo port and simulate the transportation process of it through a queueing model. The results of the simulation are summarized as follows: The average arrival interval of the domestic vessel is 6.034 hours. The average service time and the berth utility rate are 24.056 hours and over 100%, respectively. The average arrival interval of the oceangoing vessel is 34.48 hours. The average service time and the berth utility rate are 120.04 hours and the 34.91%, respectively. The proposal to improving of the Mokpo port as follows: It is desirable to extend the capacity of domestic pier to about 50% for the optimal utility rate of 70% and in the case of oceangoing pier to be increase 65% of the vessel capacity for the optimal utility rate of 70%.

• Computers and Concrete
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• 제29권2호
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• pp.69-79
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• 2022

For long underground box utility tunnels, post-tensioned precast concrete is often used. Between precast tunnel segments, sealed waterproof flexible joints are often specified. Fault displacement can lead to excessive deformation of the joints, which can lead to reduction in waterproofing due to diminished contact pressure between the sealant strip and the tunnel segment. This paper authenticates utilization of a finite element model for a prefabricated tunnel fault-crossing founded on ABAQUS software. In addition, material parameter selection, contact setting and boundary condition are reviewed. Analyzed under normal fault action are: the influence of fault displacement; buried depth; soil friction coefficient, and angle of crossing at the fault plane. In addition, distribution characteristics of the utility tunnel structure for vertical and longitudinal/horizontal relative displacement at segmented interface for the top and bottom slab are analyzed. It is found that the effect of increase in fault displacement on the splice joint deformation is significant, whereas the effects of changes in burial depth, pipe-soil friction coefficient and fault-crossing angle on the overall tunnel and joint deformations were not so significant.

• 대한교통학회지
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• 제24권6호
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• pp.103-117
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• 2006

본 연구에서는 개별 관광객을 Simulation하는 모형을 개발하고. 이를 이용해 첨단 관광정보시스템 하에서의 여행객의 관광지 선택행태 변화와 관광 수요 패턴의 변화를 분석하였다. 관광객의 여행계획 목적함수는 기대효용 최대화로 가정하였고, 교통망에서 순차적 방문 계획 해를 얻기 위해 Traveling Salesman Problem(TSP)을 이용하였다. 단 관광객들의 경우 하루 동안 주어진 여행시간과 여행예산의 제약이 존재하기 때문에, 제약이 존재하는 TSP. 즉 Prize-Collecting TSP를 이용하였으며, 하루 이상 관광지에 체류하는 관광객들의 여행계획 문제를 풀기위해 Prize-Collecting Multiple-Day TTaveling Salesman Problem(PC MD TSP)을 개발하였다 관광 정보의 형태는 사전정보, Oft-line 정보. On-line 정보로 구분하여, 전체 관광객들을 이용 가능한 정보 형태에 따라 3가지 계층으로 구분하였으며. Simulation을 통해 각 관광지의 관광객을 계산하였다. 개발된 모형을 통해 Ubiquitous 환경에서의 On-line 정보가 관광객들뿐만 아니라 관광지에도 수요증가에 따른 운영 이익 증대를 가져다 줄 수 있음을 확인하였다.

• 한국철도학회논문집
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• 제12권5호
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• pp.656-662
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• 2009

일반적으로 교통수단선택 모형은 이용자의 인구 및 개인통행특성 등을 반영한 수단별 선호도를 효용함수로 구축하여 분석하고 있다. 본 연구에서는 이용자의 출발지에 대한 공간적 연관성을 수단선택모형에 고려한 방법을 제시하였다. 이를 위하여 공간적 연관성을 포함하는 공간로지스틱 회귀모형을 고려하였다. 신뢰성있는 추정값을 얻기 위해 베이지안 기법을 적용하였으며 이 연구에서 제시한 방법론은 수단선호도 조사가 이루어지지 않은 지역에 대해서도 수단분담률을 추정할 수 있을 것으로 기대된다.

• 한국의상디자인학회지
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• 제17권4호
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• pp.67-76
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• 2015

The purpose of this study is to set a direction for the development of men's underwear after analyzing current applications for patent regarding men's special-purpose underwear. In terms of a research method, the disclosed patents and utility models were investigated using the patent information database provided by Korea Institute of Patent Information (KIPRIS, http://www.kipris.or.kr). For this, the patents applied from 1990 to October 2015 were targeted. The keywords used for patent search were 'men's underwear' and 'men's special-purpose underwear.' When searched by the keywords above, a total of 1,089 cases were found. Except for expired or cancelled ones, 243 cases were investigated. Then, annual application trends, current registrations on literature records, classification of utility model right holders and contents by topic were analyzed. In terms of data analysis, frequency analysis, crosstabulation analysis and multiple response analysis were conducted, using SPSS 18.0. The results found the followings: In terms of annual application trends, the number of applications for patent started to gradually increase since 2007. Since 2011, it has rapidly increased. In terms of the number of patent registrations, literature registration was far higher than utility model registration. In terms of application rights, 'individually registered (58.8%)' was higher than 'registered by the organization (41.2%).' Among 243 cases, 'underwear (58%)' was the highest, followed by 'men's underwear-related items (29.2%)' and 'thermals (8.2%).' According to analysis on the details of the patent applied for men's underwear, 'penis-scrotum separation' was most focused, followed by 'disposable product' 'airy features,' 'scrotum protection' and 'structure of underwear.'

• 한국안전학회지
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• 제31권3호
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• pp.143-155
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• 2016

Recently, a massive loss of life and property is occurring in Korea due to traffic accidents, with the rapid increase in cars. For improvement of traffic safety, the Korea Transportation Safety Authority intensively analyzes accident data in local governments with low traffic safety index, performs a field investigation to extract problems and offers local governments improvements for problems, by conducting the 'Special Survey of Actual Conditions of Traffic Safety' each year, starting 2008. But local governments cannot strongly push forward the improvement projects due to the limited budget and the uncertainty of the improvement plan effects. Therefore, this study suggested a model which applied the Utility concept to the AHP theory, in order to efficiently decide a priority of the improvement plans in accident black spots in consideration of the limited budget of local governments. The number of accidents in each spot for improvement and accident severity, traffic volume, pedestrian volume, the improvement project cost and the accident reduction effect were chosen as evaluation factors for deciding a priority, and data about the improvement plan costs and the accident reduction effects, traffic accidents and traffic volume in the spots to undergo the special research on the real condition of traffic accident in the past were collected from the existing studies. Then, regression analysis was carried out and the Utility Curve of each evaluation factor was computed. Based on the AHP analysis findings, this study devised a priority decision method which calculated the weight and the utility function of each evaluation factor and compared the total utility values. The AHP analysis findings showed that among the evaluation factors, accident severity had the biggest importance and it was followed by the improvement plan cost, the number of accidents, the improvement effect, traffic volume and pedestrian volume. The calculated utility function shows a rise in utility, as the variables of the 5 evaluation factors; the number of accidents, accident severity, the improvement plan effect, traffic volume and pedestrian volume increase and a fall in utility, as the variables of the improvement plan cost increase, since the improvement plan cost is included in the budget spent by a local government.

• 한국터널지하공간학회 논문집
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• 제19권1호
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• pp.29-39
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• 2017

본 연구에서는 3면이 지중과 접하는 형태의 전력구에서 온도상승을 방지하기 위한 환기시스템 설계에 필요한 벽면에서 열전달계수 등 열설계 자료를 수치해석적인 방법으로 검토하였다. 수치해석 모델은 터널 벽체에서의 열전달을 고려하기 위해서 전력구의 터널의 라이닝을 포함하는 것으로 모델링하였으며, 전력구에 설치되는 전력케이블의 발열량(117~468 kW/km), 전력구내 풍속(0.5~4.0 m/s)에 따른 터널내 공기온도 및 벽체온도, 벽체를 통한 발열량을 CFD시뮬레이션에 의해서 구하였다. 또한 해석결과로부터 벽체열전달계수를 계산하고 환기구간의 터널내 공기온도를 유지하기 위한 한계거리를 검토하였다. 벽체표면에서 대류열전달계수는 입구영역에서는 불안정한 변화를 보이나 약 100 m정도의 이후에는 일정한 값에 수렴한다. 터널벽체열전달계수는 풍속에 따라 $3.1{\sim}9.16W/m^2^{\circ}C$정도이며, 이를 무차원식으로 표현하면 $Nu=1.081Re^{0.4927}({\mu}/{\mu}_w)^{0.14}$이 된다. 열저항 해석기법에 의해서 터널내 온도 예측방법을 제시하였으며, 약 3%이내의 편차로 예측이 가능한 것으로 평가되었다.