• ETRI Journal
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• 제43권3호
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• pp.459-470
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• 2021

This paper presents a low-cost prototype for monitoring online the maximum power produced by a domestic photovoltaic (PV) system using Internet of Things (IoT) technology. The most common tracking algorithms (P&O, InCond, HC, VSS InCond, and FL) were first simulated using MATLAB/Simulink and then implemented in a low-cost microcontroller (Arduino). The current, voltage, load current, load voltage, power at the maximum power point, duty cycle, module temperature, and in-plane solar irradiance are monitored. Using IoT technology, users can check in real time the change in power produced by their installation anywhere and anytime without additional effort or cost. The designed prototype is suitable for domestic PV applications, particularly at remote sites. It can also help users check online whether any abnormality has happened in their system based simply on the variation in the produced maximum power. Experimental results show that the system performs well. Moreover, the prototype is easy to implement, low in cost, saves time, and minimizes human effort. The developed monitoring system could be extended by integrating fault detection and diagnosis algorithms.

• 한국항공운항학회지
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• 제31권2호
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• pp.81-88
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• 2023

SHM (Structural Health Monitoring) technique for monitoring aircraft structural health and damage, EHM (Engine Health Monitoring) for monitoring aircraft engine performance, and APM (Application Performance Management) is used for each function. APMS (Airplane Performance Monitoring System) is a program that comprehensively applies these techniques to identify the difference between the performance manual provided by the manufacturer and the actual fuel mileage of the aircraft and reflect it in the flight plan. The main purpose of using APMS is to understand the performance of each aircraft, to plan and execute flights in an optimal way, and consequently to reduce fuel consumption. First, it is to check the fuel efficiency trend of each aircraft, check the correlation between the maintenance work performed and the fuel mileage, find the cause of the fuel mileage increase/decrease, and take appropriate measures in response. Second, it is to find the cause of fuel mileage degradation in detail by checking the trends by engine performance and fuselage drag effect. Third, the APMS is to be used in making maintenance work decisions. Through APMS, aircraft with below average fuel mileage are identified, the cause of fuel mileage degradation is identified, and appropriate corrective actions are determined. Fourth, APMS data is used to analyze the economic analysis of equipment installation investment. The cost can be easily calculated as the equipment installation cost, but the benefit is fuel efficiency improvement, and the only way to check this is the manufacturer's theory. Therefore, verifying the effect after installation and verifying the economic analysis is to secure the appropriateness of the investment. Through this, proper investment in fuel efficiency improvement equipment will be made, and fuel efficiency will be improved.

• 한국농공학회논문집
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• 제60권5호
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• pp.115-124
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• 2018

Resilience has been widely used in various fields including design and operation of infrastructures. The resilient infrastructures not only reduce the damage scale of various disasters but also reduce the time and cost required for restoration. However, resilience rarely applied to promote efficient management of agricultural infrastructures. Recently, drought is an aggravating disaster by climate change and need countermeasures. Therefore, we tried to demonstrate evaluating measures in case of drought under consideration of resilience. This study applied the robustness-cost index (RCI) to evaluate alternative solution of the supply problem of a large agricultural reservoir under drought conditions. Four structural alternatives were selected to estimate the robustness index (RI) and the cost index (CI) to obtain the RCI values. Structural alternatives are classified into temporary measures and permanent measures. Temporary measures include the development of a tube wells and the installation of the portable pump, while the permanent measures include the installation of a pumping stations and the pumping water to the reservoir (Yeongsan River-Naju reservoir). RCI values were higher in permanent measures than those of temporary measures. Initial storage of the reservoir also affected RCI values of the drought measures. Permanent measures installation and management of early stage of the reservoir storage shortage was identified as the most resilient system.

• 한국ITS학회 논문지
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• 제11권6호
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• pp.49-59
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• 2012

최근 사업용 자동차에 대한 다양한 대책방안이 요구되고 있으며, 디지털 운행기록장치가 새로운 대안으로 제시되고 있다. 국내에서는 2011년 1월 1일부터 단계별로 사업용 자동차의 디지털 운행기록장치(DTG, Digital Tachograph) 장착을 법적으로 의무화하였으며, 2011년 이후 교통안전공단에서는 디지털 운행기록장치를 활용한 운행기록분석시스템을 구축 중에 있다. 운행기록분석시스템에서 실시간으로 수집되는 운전자의 위험운전행동, 운행거리 등 실시간 운행기록을 바탕으로 한 기대효과를 분석한 사례는 국내외 모두 미미한 상태이다. 본 연구에서는 운행기록분석시스템을 통해 수집된 자료와 운수회사 자료를 바탕으로 운전자별 위험운전행동변화 추이, 교통사고변화 추이 및 교통사고 절감비용, 연료소모량 변화 추이 및 연료비 절감비용, $CO_2$를 중심으로 한 사회적 편익 증가효과를 추정하였다. 또한 위험운전행동건수를 통해 차량을 3개의 위험운전그룹으로 구성하여 연료비 절감비용과 사회적 편익 증가효과를 재추정하였다. 고위험운전군의 연비는 저위험운전군 대비 버스, 택시는 약 15%이상 낮고 트럭은 30%이상 낮다. 고위험운전군에서 저위험운전군간 $CO_2$ 배출량의 격차는 버스, 택시, 트럭이 각각 25%, 25%, 42%로 매우 큰 것으로 분석되어 저위험군으로 전이가 중요한 것으로 판단된다. 본 연구는 실시간 운행기록을 활용한 안전 및 경제적, 사회적 기대효과를 단기간이지만 거시적인 측면에서 효과분석을 수행하였으며, 향후 장기간 자료가 수집될 경우 효과분석 할 수 있는 틀을 제시하였다.

• 한국지리정보학회지
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• 제21권3호
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• pp.63-75
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• 2018

본 연구는 한국의 S시를 대상으로 CCTV 설치로 인한 경제적 및 공간적(범죄전이 및 확산) 차원에서 긍 부정적 효과를 실증 분석하였다. CCTV 설치(2012년, 2013년)로 인한 경제적인 효과측면에서 CCTV 설치 비용, 범죄건수, 건당 범죄비용을 사용하여 비용편익분석을 실시하였다. 분석결과 2012년은 1.34(34%)의 효과가 있는 것으로 분석되었으며, 이 결과는 미국의 사례(비용 효과성 1.49)와 비교하여 다소 낮은 수준이지만 한국의 사례(비용효과성 1.32)보다는 조금 높게 나타나 사례지역의 경우 CCTV신규 설치가 범죄감소를 통해 투입예산 대비 경제적 이윤효과를 얻고 있다는 증거를 보여준다. 하지만 2013년의 경우는 경제적 이윤효과가 없는 것으로 분석되었다. 두 번째로 공간적(범죄전이 및 확산) 차원에서 범죄전이값 WDQ라는 분석도구를 활용하여 분석을 실시하였다. 그 결과 3개 지역의 총범죄는 확산효과가 있으나 직접효과보다 적은편이며, 1개 지역은 전이효과가 있으나 직접효과 보다 적은 것으로 분석되었다. 절도와 폭력의 경우도 1개 지역을 제외하면 CCTV 설치로 인해 긍정적인 순효과가 나타났다. 종합해 보면, 분석결과가 상이하며 이는 범죄종류 및 범죄 장소에 따라서 선택적인 효과를 나타내고 있는 것으로 판단된다. 본 연구의 결과는 CCTV 설치 후 범죄전이효과 및 범죄통제 이익의 확산효과에 대한 연구가 부족한 시점에서 CCTV 설치 효과를 과학적이고 합리적인 측정도구를 활용하여 확인 할 수 있었다는 점에서 그 의의가 높다고 판단된다.

• 한국통신학회논문지
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• 제24권7B호
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• pp.1220-1228
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• 1999

이 연구는 멀티미디어 서비스를 제공하는 중요한 망 설계 문제를 다룬다. 이 연구에서 다루는 문제는 게이트웨이 위치와 광케이블 경로를 정하는 문제로서 가능한 한 총비용을 최소화하는 소넷링을 설계한다. 고려하는 비용은 게이트웨이와 전화국에 설치되는 가감 다중화기(Add-Drop Multiplexer)의 설치비용과 광케이블의 선로 비용이다. 이를 해결하기 위하여 먼저 최적화모형을 제시하고, 효율적인 해법으로서 몇 가지 휴리스틱 방법을 개발한다. 몇 가지 예제를 수행한 결과는 두 해법의 총비용 절감 효과를 보여준다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.166-167
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• 2014

Recently, in according to increase cognizance of energy and resources exhaustion, renewable energy system is received attention. In particular, ground heat pump system(GSHP) utilizing annually stable ground temperature for energy saving have been attracted in many buildings. However, GSHP system have disadvantage due to increase of initial installation and boring cost. In this study, in order to reduce the initial cost and to supply ground heat pump system into small scale house, an unit-type ground heat exchanger was developed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.181-183
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• 1999

As one of ancillary services, voltage support and reactive power service should be compensed properly for its contribution. In this paper, a cost-based reactive power planning is presented. which minimizes the total cost of reactive power support of generators and VAR compensation facility installation. Reactive power support of generator is evaluated by the opportunity costs of reduced energy sale considering the varying SMP(system marginal price) in power market, Gradient projection method is applied to solve this reactive power planning using IEEE14 bus system.

• 대한전기학회논문지:전력기술부문A
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• 제48권7호
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• pp.839-846
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• 1999

This paper presents an efficient algorithm for determining the location, size and number of capacitors in unbalanced radial distribution system. The objective function formulated consists of two terms: cost for energy loss and cost related to capacitor purchase and capacitor installation. The cost function associated with capacitor placement is considered as step function due to banks of standard discrete capacities. Genetic algorithms(GA) are used to obtain the population is derived. The strings in each population consist of the bus number index and size of capacitors to be installed. In order to determine the number of capacitor placement, the length mutation operator is used. Its efficiency is proved through the application in unbalanced radial distribution systems made of 10 buses with 9 distribution lines and 25 buses with 24 distribution lines.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2002년도 추계학술대회
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• pp.17-23
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• 2002

Value can be defined as function divided by cost. The ultimate goal of VE (Value Engineering) is to simultaneously reduce cost and to enhance function in given projects. In general, there are eight phases (Selection, Investigation, Speculation, Evaluation, Development. Presentation, Implementation, and Audit) to perform VE. This paper presents analysis of important factors for VE in construction fields using QFD (Quality Function Deployment) technique. QFD was introduced in 1972 to help design supertanker in Mitsubish's shipyards in Kob, Japan and formally defined by the American Supplier Institute in 1987 as a system for translating consumer requirements into appropriate company requirements at every stage, from research, through product design and development, to manufacture, distribution, installation, and marketing, sales and services. The objective of this paper is to provide and analyze the trend on the viewpoint of efficient value engineering of field workers. The data are collected by questionnaires. The samples for this study are chosen from 13 companies in Korea during 2 months (2002. 7 ∼ 2002. 8). The results of this study will play an important role not only for the efficient value engineering but also for preparing of life cycle cost analysis.