• 한국산학기술학회논문지
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• 제16권6호
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• pp.4253-4259
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• 2015

본 연구에서는 자연외기를 활용하여 건물의 에너지절약을 위한 외기냉방제어 시스템에 대하여 다양한 제어방법에 따른 제어특성 및 에너지 소비량에 미치는 영향에 관해 시뮬레이션 연구를 수행하였다. 연구 방법으로는 TRNSYS 프로그램을 활용하여 시스템 해석 모델링을 수행하였으며, 외기 냉방을 하지 않은 경우와 기존의 외기냉방 제어방법들을 적용하였을 경우에 대해 제어성능에 대한 비교 분석이 이루어졌다. 연구 결과로 외기온도 변화에 따라 적절한 외기도입 온도조건을 선정하는 것이 에너지 절감에 효과적이며, 외기와 환기온도를 비교하여 온도제어하는 방법이 에너지 절감효과가 가장 크게 나타남을 알 수 있었다.

• Architectural research
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• 제19권4호
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• pp.101-108
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• 2017

The use of the air conditioner is increasing due to the rise of the outdoor temperature during summer, and the problems of the fire and the cooling performance deterioration are caused due to lack of maintenance of the outdoor unit. In particular, overall performance of cooling system and efficiency in outdoor units have been degraded due to an intake of high-temperature outdoor air thereby increasing cooling energy and operating cost. Thus, this study aimed to increase efficiency of outdoor units by evaporating and cooling intake air through mist spray at the intake port surface in the outdoor unit. The measurements results showed that total power consumption of misting outdoor unit compared to that of conventional outdoor units was reduced by 21% approximately, and total power consumption of the entire system including pump was reduced by 16.7%. In addition, the operating cost including water use was reduced by 13.5% approximately. In summary, if a mist-spray nozzle kit is installed in air-cooled outdoor units, the reduction in the usage of cooling energy and operating cost will be achieved without replacement of existing cooling systems or a large scale of repairs.

• KIEAE Journal
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• 제16권6호
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• pp.13-19
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• 2016

Purpose: In this study, we examined outdoor air fraction using historical data of actual Air Handling Unit (AHU) in the existing building during intermediate season and analyzed optimal outdoor air fraction by control types for economizer. Method: Control types for economizer which was used in analysis are No Economizer(NE), Differential Dry-bulb Temperature(DT), Diffrential Enthalpy(DE), Differential Dry-bulb Temperature+Differential Enthalpy(DTDE), and Differential Enthalpy+Differential Dry-bulb Temperature (DEDT). In addition, the system heating and cooling load were analyzed by calculating the outdoor air fraction through existing AHU operating method and control types for economizer. Result: Optimized outdoor air fraction through control types was the lowest in March and distribution over 50% was shown in May. In case of DE control type, outdoor air fraction was the highest of other control types and the value was average 63% in May. System heating load was shown the lowest value in NE, however, system cooling load was shown 1.7 times higher than DT control type and 5 times higher than DE control type. For system heating load, DT and DTDE is similar during intermediate season. However, system cooling load was shown 3 times higher than DE and DEDT. Accordingly, it was found as the method to save cooling energy most efficiently with DE control considering enthalpy of outdoor air and return air in intermediate season.

• 한국지열·수열에너지학회논문집
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• 제7권2호
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• pp.30-36
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• 2011

In this study, energy saving performance of outdoor temperature reset control strategy for central cooling system is researched by experiments. Outdoor temperature reset control is the control method to change indoor air set temperature according to outdoor air temperature change. The range of indoor air set temperature is represented by the comfort temperature range of indoor air temperature offered from ASHRAE and indoor air set temperature is programmed between $22^{\circ}C$ and $27^{\circ}C$ by outdoor air temperature $20^{\circ}C{\sim}32^{\circ}C$ in summer. As a result of applying outdoor temperature reset control to central cooling system, the suggested control method shows better performances of energy savings than the conventional method which indoor temperature maintains constantly.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.826-831
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• 2006

In this paper, we discussed the energy performance of underfloor air distribution(UFAD) and overhead air distribution system according to outdoor air intake rates in a office building. For this, the laboratory(S lab.) is selected for measuring the thermal environments of UFAD system and overhead system. Based on the measured data, the TRNSYS simulation is used to evaluate the energy performance of UFAD system and the overhead system according to outdoor air intake rates. By increasing outdoor air intake rates from required outdoor air intake rates(100CMH) to maximum air intake rates, the energy savings of UFAD system comparing with overhead system are varied $15%{\sim}25.6%$ in summer, $12.8%{\sim}19%$ in fall/spring and not varied in winter(8%). As results of simulations on stratification height and cooling set temperature, the lower the stratification height and the higher cooling set temperature, the larger cooling energy savings of UFAD comparing with overhead system according to outdoor air intake rates.

• 한국지열·수열에너지학회논문집
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• 제17권4호
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• pp.68-78
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• 2021

In order to solve the increasing deterioration of the energy shortage problem, ground-source heat pump (GSHP) systems have been widely installed. The control method is a significant component for maintaining the long-term performance and for reducing operation cost of GSHP systems. This paper presents the measurement and analysis results of the cooling performance of a GSHP system using capacity control with outdoor air temperature. For this, we installed monitoring equipments including sensors for measuring temperature, flow rate and power consumption, and then monitored operation parameters from July 9, 2021 to October 2, 2021. From measurement results, we analyze the effect of capacity control with outdoor air temperature on the cooling performance of the system. The average performace factor (PF) of the heat pump was 6.95, while the whole system was 5.54 over the measurement period. Because there was no performance data of the existing GSHP system, it was not possible to directly compare the existing control method and the outdoor air temperature method. However, it is expected that the performance of the entire system will be improved by adjusting the temperature of cold water produced by the heat pump, that is, the temperature of cold water on the load side according to the outside air temperature.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.322-327
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• 2007

Dedicated outdoor air-conditioning(DOA) system that utilizes pre-cooling and desiccant dehumidification can be superior to conventional cooling and reheating system with respect to energy consumption and indoor thermal comfort. In this work, simulation has been conducted to study various factors that affect the performance of DOA. Dynamic simulation shows the transient variation of temperature and humidity as the on/off control logic is imposed. Exit humidity of process air and flow rate are varied to study the effect on exit temperature of process air, dehumidification quantity, required regeneration temperature and exit humidity of regeneration air. For an outdoor air condition of $28.5^{\circ}C$ temperature, 16 g/kg humidity ratio and 2000 cmh flow rate, the dehumidification efficiency is increased by 4.6% as the flow rate is doubled.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.591-596
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• 2008

The present study has been conducted to study the performance of dedicated outdoor air handling unit in central and personal air-conditioning. With conventional central and personal air-conditioning systems which are designed according to the maximum load, humidity increase above comfort level can not be avoided as the cooling load decreases. The adoption of dedicated outdoor air handling unit, however, can solve this problem. Moreover, the dedicated outdoor air handling unit has the characteristics of anti-bacteria due to dry coil, energy saving and good indoor air quality. During cooling seasons, dedicated outdoor air handling unit can save energy up to 30% than the conventional cooling+reheating system for controlling both temperature and humidity.

• 한국지열·수열에너지학회논문집
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• 제7권1호
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• pp.51-58
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• 2011

Due to enhanced sealing and insulation of buildings, extensive use of glasses for building envelopes and increased use of heat generating office equipments, energy consumption of modem buildings for cooling is steadily increasing. With outdoor air cooling(ODAC) system, cooling load can be reduced by exchanging indoor air with the cold outdoor air during spring and fall seasons. If ODAC is operated based only on temperature, total cooling load may virtually increase if the outdoor humidity is high. To overcome this problem, ODAC should be controlled based on enthalpy. In this work energy saving characteristics of enthalpy controlled ODAC is studied using dynamic simulation. The result shows that cooling load can be reduced by 27% by adopting ODAC.

• 설비공학논문집
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• 제13권11호
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• pp.1165-1173
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• 2001

The objectives of this study are to analyze the application of radiant floor cooling and to evaluate the control methods through experiments when the radiant heating system is used for cooling. Through the experiment analysis the control methods such as on/off control, variable flow control and outdoor reset with indoor temperature feedback control are evaluated and compared. The cooling curve (reset ratio) is found for radiant cooling, which shows tole relation between outside air temperature and supply water temperature. Comparison of cooling methods shows that outdoor reset with indoor temperature feedback control is more appropriate than on/off control and variable flow control with regard to prevention of the condensation and thermal comfort.