• KIEAE Journal
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• 제17권2호
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• pp.29-34
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• 2017

Purpose: Recently, significant heat loss through the window takes place in buildings. Nevertheless, there exists little literature concerning the exterior horizontal shading devices and the design criteria are not clearly settled yet. Applying the exterior horizontal shading devices is more efficient as compared to the interior shading devices in that solar radiation can be directly blocked before passing through the window or the envelope. The purpose of this study is to reduce the internal load by designing the exterior horizontal shading devices and verify the degree of reduction in energy consumption. Method: This study aims to reduce energy consumption in cooling and heating through proposing proper length and shape of the exterior horizontal shading devices in public buildings. In the process, actual energy data and the Design Builder simulation program are utilized. In addition, economic aspect is considered to figure out the optimal length of the exterior horizontal shading devices that maximizes efficiency. Result: As a result, the proper length and shape of the exterior horizontal shading devices are provided as follows: 1) Energy consumption in cooling and heating is minimized when the exterior horizontal shading devices are designed as 0.5m*2. 2) Electricity bill is the lowest when the exterior horizontal shading devices are designed as 3.3m*2. The gap between maximum and minimum electricity bill is about 7.8~14%.

• 대한토목학회논문집
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• 제30권4A호
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• pp.391-398
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• 2010

본 연구에서는 반단면 프리캐스트 패널을 갖는 RC 슬래브에 대해서 비재하 상태에서 ISO-834 화재곡선을 적용한 가열시험을 수행하였다. 가열시험시 PP섬유 혼입되지 않은 실험체에서는 콘크리트의 폭렬이 발생되고, PP섬유가 혼입된 실험체에서는 폭렬이 발생되지 않았다. PP섬유가 혼입된 반단면 프리캐스트 패널을 적용한 RC 슬래브의 발생온도는 PP섬유가 혼입되지 않은 경우보다 낮은 수준을 보였다. 화재 가열실험 후 상온상태로 냉각된 RC 슬래브의 극한하중을 평가하기 위하여 3점 휨실험을 수행하였다. 실험결과, PP섬유가 혼입되지 않은 RC 슬래브는 PP섬유가 혼입된 실험체와 비교해 약 32.5% 정도 극한하중이 감소하는 결과를 보였다. 또한, PP섬유가 혼입된 반단면 프리캐스트 패널을 갖는 RC 슬래브의 극한하중은 PP섬유가 혼입된 전두께 RC 슬래브보다 큰 수준을 보였다. 이상의 결과에서 PP섬유의 혼입과 반단면 프리캐스트 패널 적용시 화재에 대한 저항능력이 향상됨을 확인하였다.

• 한국분무공학회지
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• 제25권4호
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• pp.170-177
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• 2020

Stoichiometric combustion in spark ignition (SI) engines has an advantage of meeting future stringent emission regulations. However, the drawback of the combustion is a lower thermal efficiency than that of lean burn. In this study, energy losses in a natural gas stoichiometric SI engine generator were analyzed to establish a strategy for improving the generating efficiency (GE). The energy losses were investigated based on dynamometer and load bank experiments. As the intake manifold pressure increased in the dynamometer experiment, the brake thermal efficiency (BTE) increased mainly due to the reduction in the pumping and mechanical losses. In the load bank experiment, the generating power and GE increased with the increased intake manifold pressure. The generating power and GE were lower than the brake power and BTE due to the cooling fan power and the losses in the generator.

• 한국기계가공학회지
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• 제16권3호
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• pp.16-23
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• 2017

For most machine tools, it is necessary to remove chips and coolant oil because it they will continue to be created during the manufacture of workpieces. Existing products that are in use are installed and used as they reflect depending on the characteristics of each device separately. This study proposes a method to remove the security chip as well as developing an integrated system capable of reducing coolant damage. The Leverage AutoCAD and CATIA program was used for 2D and 3D design, shapes were identified by utilizing the KeyShot program, and the load and displacement analysis of the development apparatus was performed utilizing the ANSYS program. After the prototype underwent sufficient design review, the mixed oil separation device had a complete sensor control program using the LabVIEW program. The chip design process for transferring experiments and experiments on the mixed oil cooling device were developed for performance tests of the product. The final product resulted in an increase in space utilization during commercialization, reduced installation costs, and caused social effects such as pulmonary flow reduction, which, through the economic costs, reduces pollution, resulting in various benefits to the industry, such as deceased errors in the workplace decreases.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2012년도 춘계학술논문집 2부
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• pp.579-582
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• 2012

본 논문에서는 쿨튜브를 적용한 식물공장 이중창호와 삼중창호의 열전달 차단성능을 3차원 수치해석을 통해 비교분석하였다. 이중창호 설계변수인 유입구의 개수와 중공층 두께조건에 따라 창호를 통해 식물공장 외부에서 내부로 유입되는 열전달량을 분석하였다. 쿨튜브를 통해 중공층으로 유입되는 공기속도가 이중창호에서는 0.95 m/s, 삼중창호의 경우는 0.50 m/s 이상일 때 창호를 관통하여 외부에서 내부로 유입되는 열에너지가 차단되는 결과를 얻었다. 삼중창호의 경우에 중공층 유입 공기속도를 0.50 m/s 이상으로 증가시킬 경우 오히려 식물공장 내부의 열에너지가 중공층으로 빠져나가 실내온도를 낮추는 효과가 나타났다. 본 연구의 결과를 바탕으로 국내 지역별 기후데이터의 온도조건을 고려한 분석을 추가적으로 진행할 계획이다.

• KIEAE Journal
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• 제15권3호
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• pp.93-99
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• 2015

Purpose: Various studies on the soil-based green roof systems have been conducted, and a lot of green roof systems were developed. A growing medium board is one of them which was developed for better application and maintenance, however the effect and performance of this material need to be verified. On this background, the purpose of this study is to prove cooling load reduction of green roof by monitoring experiment on the full-scale mock-ups. Method: To do this, Solid growing medium boards were installed on the mock-ups, and indoor temperature and humidity were monitored and analyzed. Result: As a results, the green roof with solid growing medium board were verified effective for controlling indoor temperature in summer.

• 한국소음진동공학회논문집
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• 제14권11호
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• pp.1137-1146
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• 2004

In an apartment house In Korea, the balcony is one of the important spaces as a buffer zone for controlling the outdoor environments such as noise, heating & cooling load, humidity etc. Because most areas of building facade in apartment building occupy the area of balcony window the sound Insulation design of It Is very Important to provide the quiet indoor environment. The aim of this research is to evaluate the sound insulation of balcony windows in apartment building by new and revised Korean Industrial Standards. We measured and studied the sound insulations of 18 balcony windows by the type of measuring methods, noise sources, correction of reverberation time in balcony and so on. The results show that the single-number quantities for sound insulation of windows are ranged from 24 dB to 30 dB.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2000년도 KIASC Conference 2000 / 2000년도 학술대회 논문집
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• pp.35-38
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• 2000

A preliminary design of gas-gp thermal switch is presented to reduce the cooldown time of superconducting system conduction-cooled by a two-stage refrigerator without liquid cryogens. The switch connects thermally the first and the second stages (ON) to take advantage of the larger refrigeration capacity at the first stage during the beginning period. After the cryogenic temperature is reached, the switch should isolate thermally the two stages (OFF) in order to reduce the heat leak to the cold end. In this paper, a new concept for the performance index is introduced to evaluate the reduction of the cooldown time and the increase of the cooling load at the same time. In addition, the design of a gas-gap switch is discussed as a closed container of several staggered concentric tubes filled with gas, which is frozen at low temperatures for the shut-off of heat without any mechanical actuation. Some of the detailed features in the design is quantitative investigated by the gas convection model in the continuum or the rarefied gas region.

• KIEAE Journal
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• 제7권4호
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• pp.57-62
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• 2007

At the moment, the reduction of building energy consumption is a unavoidable task of mankind for conserving global environment. Decreasing overall U-value of building envelope and air infiltration, especially in Korean climate condition with clear four seasons, are the obvious solutions for the objective. Thus low glazing ratio with small window openings are required for heating and cooling load reduction in buildings. Using larger window openings could provide better natural ventilation but it also increases the direct solar radiation penetration into indoor space, heat gain in summer and heat loss in winter. On the other hand, the ventilation rates decreasing problem with smaller window openings could be occurred. As a solution for it, the use of casement window can cause increasing natural ventilation rates by wing wall effect. This paper focuses on deduce the most efficient opening type of casement window in Korean climate. To estimate ventilation performance of each opening types, CFD simulation was used. The best performance of opening type in every wind direction is opening both windows to the center and the most appropriate opening type for Korean climate is also opening both windows to center.

• KIEAE Journal
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• 제15권4호
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• pp.37-43
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• 2015

Purpose : The study applied control strategy to reduce through optimal control and operation of pump by applying control on variable speed to the circulation pump of HVAC system in the office building. The study has the purpose to review validity of control on variable speed as ESMs(Energy Saving Measures) and establish the control technology on variable speed pump. The study performed reduction analysis of building energy and economic evaluation of pump through energy effectiveness control strategy of HVAC system. Method: The study sought possible reduction through energy control strategy which can provide proper flow fitting to building load by applying control on variable speed pump. The study applied control strategy to reduce through pressure differential set-point control and operation of pump by applying control on variable speed to the circulation pump of HVAC system in the office building. Result : The results showed that about 16-35% of pump energy could be saved by using these optimal control strategies. In the result of analysis on 10 years life cycle cost of analysis on payback period of initial investment pump, variable speed pump control showed 5.1 years.