• 설비공학논문집
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• 제28권9호
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• pp.355-360
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• 2016

Continuing to the modeling of heating load, this paper, as the second part of consecutive works, presents LS-SVM (least square support vector machine) based model of winter time apartment hot water supply load in a district heating system, so as to be used in prediction of heating energy usage. Similar, but more severely, to heating load, hot water supply load varies in highly nonlinear manner. Such nonlinearity makes analytical model of it hardly exist in the literatures. LS-SVM is known as a good modeling tool for the system, especially for the nonlinear system depended by many independent factors. We collect 26,208 data of hot water supply load over a 13-week period in winter time, from 12 heat exchangers in seven different apartments. Then part of the collected data were used to construct LS-SVM based model and the rest of those were used to test the formed model accuracy. In modeling, we first constructed the model of district heating system's hot water supply load, using the unit heating area's hot water supply load of seven apartments. Such model will be used to estimate the total hot water supply load of which the district heating system needs to provide. Then the individual apartment hot water supply load model is also formed, which can be used to predict and to control the energy consumption of the individual apartment. The results obtained show that the total hot water supply load, which will be provided by the district heating system in winter time, can be predicted within 10% in MAPE (mean absolute percentage error). Also the individual apartment models can predict the individual apartment energy consumption for hot water supply load within 10% ~ 20% in MAPE.

• 대한안전경영과학회지
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• 제16권2호
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• pp.167-174
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• 2014

Heating and air conditioning system is changing rapidly from the traditional HVAC central supply system to the individual supply system with electrical heat pump system (EHP) in Korean school buildings. The individual supply system has advantages to turn on and off individually and to adjust the thermal comfort separately, but energy is wasted in the unoccupied classroom when the last leaving occupant does not turn off the controller. If the controller is to be off automatically while the classroom is not in use, energy consumption would decrease dramatically. This project aims to cease the unnecessary EHP supply in vacant classroom by inputting the class schedule from the central control room to reduce the energy-spending. Experimental measurements were carried out between the controlled classroom that is turned off when not in use and the uncontrolled room that is turned on continually. Occupant's comfort and energy consumption were measured and compared between the controlled case and the uncontrolled case. The energy consumption of controlled classroom case is 30-60% less than that of the uncontrolled classroom case. This result shows that controlling the cooling supply for the unoccupied classroom using the class schedule can decrease the energy consumption remarkably. This supply control system can be used to conserve energy in school structures like universities.

• 산경연구논집
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• 제12권5호
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• pp.7-16
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• 2021

Purpose: This study intends to examine how VMI with consignment performs over time and find out its on-going impacts on the individual supply chain member's achievement. Research design, data, and methodology: This study formulates the mathematical model that represents two-stage supply chain system. By analyzing the numerical examples, this study compares VMI with consignment with the traditional system. Results: VMI with consignment eventually makes higher supply chain profit than the traditional system, even though it's early performance is poor. The influence of VMI with consignment on the performance of the supply chain member is distinct depending on the individual member and time. The consignment may not be helpful to increase the system profit, but it reduces the manufacturer's burden of costs. Conclusions: VMI with consignment improves the supply chain performance after all, and it still takes times until its benefit becomes fully realized. To be a successful collaboration program, VMI with consignment requires a carefully designed incentive scheme that provides the timely compensation to the individual supply chain members. This study also finds out that the consignment contract of this collaboration program plays a role of financially supporting the manufacturer at the early stage of its implementation.

• Industrial Engineering and Management Systems
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• 제12권2호
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• pp.103-111
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• 2013

This paper discusses how to manage supply chain disruption risks from natural disasters or other low-likelihood-high-impact risk drivers. After the catastrophic earthquake in Eastern Japan and the severe flood in Thailand, most companies have been attempting to re-establish the business continuity plan to prevent their supply chain from disruption. However, the challenges for managers and individual risks are often interrelated, and thus, actions that mitigate one risk can end up being no contribution as a whole. In this paper, we describe a framework for assessing how much impact individual mitigation strategies have on the entire supply chain protection against disruption, using network reliability. We propose three categories of risk-mitigation approaches: Stabilization, Absorption, and Duplication. We analyze the situation under which each of these strategies is the best suitable. With a clear understanding of relations between these mitigation strategies and the entire supply chain risks, managers can select effective risk-reduction approaches to their supply chain.

• 한국유통학회지:유통연구
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• 제7권1호
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• pp.87-103
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• 2002

본 연구에서는 동태적인 공급체인을 설정하여 개인의 의사결정 유형이 공급체인에서의 채찍현상에 어떠한 영향을 미치는 지를 설문조사, 실험, 그리고 시뮬레이션을 통해 검증하고 있다. 공급체인 참여자의 의사결정 유형은 Rowe와 Boulgarides(1992)에 의해 만들어진 의사결정유형 측정목록을 통해 구분하였으며, 채찍효과는 공급체인에서의 최대주문량과 재고량을 중심으로 분석하였다. 공급체인 모델 설정시 주안점은 주문량 결정식이다. 공급체인 참여자들은 통상 고객에 대한 서비스 수준을 충족시킬 수 있으면서 동시에 재고 비용을 최소화시킬 수 있도록 적정 주문량을 결정하기 때문이다. 본 연구에서는 맥주배송게임을 통해 기본 공급체인 모델을 설정하고 설정된 공급체인 모델을 바탕으로 개인의 의사결정 유형에 따른 공급체인에서의 채찍현상을 시뮬레이션하였다. 연구결과 개인 의사결정유형에 따라 전체 공급체인에서의 채찍효과가 달리 나타나지 않았다. 본 연구는 기존의 개인의 특성이 공급체인에서의 채찍효과에 영향을 미친다는 연구결과와는 대조되는 결과를 보여주고 있다. 공급체인에서의 채찍현상의 원인을 규명하는 작업에서 조직이나 시스템 관점에서의 접근과 개인 특성 위주의 접근 중에서 전자에 비중을 실어주는 연구결과라고 할 수 있다. 즉 공급체인에서의 채찍현상을 제거하기 위해서는 구조나 시스템 차원에서의 개선이 이루어져야 함을 간접적으로 시사함을 본 연구의 의의로 들 수 있다.

• 설비공학논문집
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• 제21권3호
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• pp.193-200
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• 2009

The ventilation system of apartments can be divided by supply and exhaust fan, supply fan and exhaust free and supply free and exhaust fan. Recently, the individual ventilation system and central ventilation system which is combined cooling system with duct system are applied to apartment ventilation system. The airflow pattern is affected by location of supply unit and exhaust unit in indoor. This study is to investigate the proper distance between supply unit and exhaust unit using CFD. As a result of this study, the proper distance between supply unit and exhaust unit could be suggested at the interval of 3 m in supply and exhaust fan system and 2.5 m in supply fan and exhaust free.

• 설비공학논문집
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• 제19권12호
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• pp.857-864
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• 2007

In the current residential building, hot water supply system consumes the second largest energy in order to make the thermal comport condition of residential space. The more residential environment improves the more the demand for hot water and water consumption is increasing gradually. So this study examines the possibility of applying the recirculation for individual hot water supply system compared with the existing method for waiting time for hot water, wasted water and energy consumption. The results are as follows. (1) In case of recirculation system method the waiting time for hot water can be reduced up to $69\sim85%$ in spring and fall period and so dose up to $77\sim85%$ in winter period. (2) The total wasted water has a little change compared with the existing method which can make the total wasted water reduced about $77\sim86%$. (3) The efficiency of hot water supply system can be improved, if the method which blocks the inflow of cold water is applied, when return pump is operated to recirculate hot water in recirculation system.

• 한국주거학회논문집
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• 제14권5호
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• pp.75-82
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• 2003

In this study, the thermal performance of the room control system is analyzed in terms of control performance, potential for coil expansion and energy consumption through experiments comparing the individual room control system and an existing system. The results of this study show that the existing system is not able to supply design water flow rate and does not accurately maintain the set point temperature in each room. However, the individual room control system can set a room air temperature for each room, for it is able to supply design water flow and accurately control the set point temperature in each room and can reduce the energy consumption compared to the existing system. Moreover, the individual room control system can reduce the number of coil division zone and facilitates the construction process, because it can extend the length of the coil division.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1459-1467
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• 2011

본 논문은 낙뢰 Surge 방호를 위하여 독립접지를 공통접지로 개선하는 효율적인 방법을 제안하였다. 낙뢰 Surge 방호를 위해서는 등전위 이론에 근거하는 공통접지방식이 적합하고, 중성선이 있는 전원계통에서는 공통접지방식을 사용하는 것이 국제적으로 통용되는 기술규격이다. 따라서 낙뢰 Surge에 취약한 문제점을 갖고 있는 기존의 중성선이 없는 전원계통과 독립접지방식을 중성선이 있는 전원계통과 공통접지방식으로 개선을 하고, 정전압소자를 이용하여 낙뢰 Surge를 방호하는 효율적인 등전위 시스템 구축 방법을 제안한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2013년도 추계학술대회
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• pp.215-218
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• 2013

본 논문은 낙뢰 Surge 방호를 위하여 독립접지를 공통접지로 개선하는 효율적인 방법을 제안하였다. 낙뢰 Surge 방호를 위해서는 등전위 이론에 근거하는 공통접지방식이 적합하고, 중성선이 있는 전원계통에서는 공통접지방식을 사용하는 것이 국제적으로 통용되는 기술규격이다. 따라서 낙뢰 Surge에 취약한 문제점을 갖고 있는 기존의 중성선이 없는 전원계통의 독립접지방식을 중성선이 있는 전원계통의 공통접지방식으로 개선을 하고, 정전압소자를 이용하여 낙뢰 Surge를 방호하는 효율적인 등전위 시스템 구축 방법을 제안한다.