• 동력기계공학회지
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• 제8권1호
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• pp.41-47
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• 2004

Cooling towers are widely used not only for cooling products and equipment in manufacturing process but HVAC(Heating, Ventilation and Air Conditioning) system. As a cooling tower is the terminal apparatus which discharges heat from industrial process, the efficiency of heat exchange in the cooling tower greatly affects to the overall performance of a thermal system. In this paper, we constituted a new water cooling system by using a Latent heat of evaporation in an enclosed tank, and this system is consisted of an enclosed vacuum tank and water driven ejector system. Several experimental cases were carried out for improvement methods of high vacuum pressure and water cooling characteristics. The ejector performance was tested in case of water temperature variations that flows into the ejector. Based on the vacuum pressure by water driven ejector, the water cooling characteristics were investigated for the vaporized air condensing effects.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.282-287
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• 2011

Of school buildings, university building requires various case analysis unlike buildings in the elementary, middle and high schools in accordance with its characteristic for variables such as characteristic of department, construction structure and material, the number of persons admitted and schedule. Through the case research on the 'D' university located in Daejeon, this study made a comparison on the monthly and yearly consumption of gas and electricity of the most recent 3 years and implemented analysis on the usage pattern and standby power of air conditioning and heating by the hour and month using PCCS(Power Consumption Consulting System) as respects electricity that is considered to have a possibility of energy-saving. The result of analysis showed that enormous amount of electric power was used during the night time for freeze protection and burst in winter season and standby power was increased in winter season as a result.

• 동아시아식생활학회지
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• 제24권5호
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• pp.680-690
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• 2014

This study investigated the performance of hygiene management according to the capacity and food cost of foodservice in kindergartens as a measure of kindergartens foodservice hygiene management. Dietitians from the education office visited 50 kindergartens under the control of Dongbu District Office of Education during January, 2011. Kindergartens were 11 public and 39 private institutions. Over half of kindergartens (n=27) provided foodservice to 50~99 children. About 21 kindergartens had a foodservice cost per student per day of 2,000 won. Regarding personal hygiene, 'whether to wear an accessory or have a manicure' showed the best performance. 'Whether to have their health examined once every 6 months or keep their health records in 2 years' was rarely performed. For food materials, 'whether to buy food appropriate for the quality control standard of food materials' showed the highest performance. The highest performances for storage management of food materials and handling of food was 'whether to store goods within butlery at intervals more than 30 cm from the ground' and 'whether to heat and cook food more than $74^{\circ}C$', respectively. The highest performance for distribution of food and management of facilities was 'the hygienic management of cooking tools and facilities' and 'the proper installation of air-conditioning, heating and ventilation facilities', respectively. The results of this study show that capacity and food cost had the strongest effects on performance of personal hygiene. Especially, smaller facility size could increase performance of foodservice management.

• 한국지능시스템학회논문지
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• 제18권1호
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• pp.60-65
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• 2008

본 논문에서는 강인 디지털 제어기를 통한 스마트 스페이스의 안정도에 대해 논의하고자 한다. 제안된 제어기 설계 방법은 지능형 디지털 재 설계 기법을 적용하는 것이다. 좀 더 구체적으로, 불확실성 및 비선형성이 포함된 아날로그 시스템을 Takagi-Sugeno 퍼지 모델을 사용하여 나타낸다. 그리고 전역적 지능형 디지털 재 설계를 위하여 해당 문제를 볼록 최적화 관점으로 변환 한 후, 에러가 가질 수 있는 놈의 영역을 최소화하여 상태 정합을 이루고자 하였다. 전역적 접근을 통해 정리된 식은 선형 행렬 부등식으로 나타나게 된다. 마지막으로, 설계된 제어기를 HVAC (Heating, ventilating, and air conditioning) 시스템에 적용함으로써 효율성을 입증하고자 한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.536-538
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• 2018

This paper introduces an enhanced interleaved (IL) PFC (Power Factor Correction) boost converter typed 650V Intelligent Power Module (IPM), which is fully optimized hybrid IGBT converter modules; Silicon (Si) IGBT and Silicon Carbide (SiC) diode, for up to 10kW HVAC (Heating, Ventilation, and Air Conditioning) systems. It utilizes newly developed $4^{th}$ Generation Field Stop (FS) trench IGBTs, $EXTREMEFAST^{TM}$ anti-paralleled diodes, SiC Junction Barrier Schottky (JBS) diodes, Bridge rectifiers, Multi-function LVIC, and Built-in thermistor provide good reliable characteristics for the entire system. This module also takes technical advantage of DBC (Direct Bonded Copper) substrate for the better thermal performance. It is shown that the Si IGBT/SiC diode hybrid IL PFC module can achieve excellent EMI performance and greatly enhance the power handling capability or switching frequency of various applications compared to the Si IGBT/Diode. This paper provides an overall description of the newly developed 650V/50A Hybrid SiC IL PFC IPM product.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.416-422
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• 2007

The application analysis of bubble pump on the domestic solar water heater system is presented. The system investigated in this study is a passive device, self pumping and self regulating. It was test to use the bubble pump on solar water heater system. The test experiment has been taken on the existed vacuum tube about the efficiency, working fluid temperature and pressure and circulated power. In order to check the working temperature and working pressure effectively, the bubble pump was test separated from the solar water heater. The equipment consists of the bubble pump, heater and heat exchanger. The main structure of bubble pump was design depend on the character of two phase flow. The complete system was instrumented to measure pressures, temperatures and their relationship with the solar radiation intensity. The theory analysis of design bubble pump has been given and the experiment result analysis has been included in the paper.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.119-124
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• 2008

Recently, focus has been drawn on natural refrigerants due to increasing concern on global warming. As a consequence, CO2 systems such as a heat pump water heater using CO2 as a refrigerant are rapidly growing on the market. Currently, rolling piston rotary compressors are widely used for CO2 heating and/or refrigeration systems. There are several ways of realizing gas compression structure. They are single stage compression with single cylinder, single stage compression with two cylinders, and two stage compression with two cylinders. In this paper, computer simulation program which was validated for a single stage rotary compressor with one cylinder has been extended for a single stage, two cylinder rotary type. Numerical investigation has been made on optimal design for the cylinder configuration using the extended simulation program. For a single stage two cylinder rotary compressor having a displacement volume of 4 cc for each cylinder, compressor efficiency has been found to be maximum when the cylinder radius and height are 31mm and 10mm, respectively.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.27-32
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• 2008

The present study has been conducted economic analysis of heat storage type ground source heat pump system(HSGSHP) and normal ground source heat pump (GSHP) which are installed at the same building in the shared an apartment house. Cost items, such as initial cost, annual energy cost and maintenance cost of each system are considered to analyze life cycle cost (LCC) and simple payback period (SPP) with initial cost different are compared. The initial cost is a rule to the Government basic unit cost of production. LCC applied present value method is used to assess economical profit of both of them. Variables used to LCC analysis are prices escalation rate and interest rate mean values of during latest 10 years. The LCC result shows that HSGSHP (1,050,910,000won) is more profitable than GSHP by 68.9% initial cost. And SPP appeared 3.0 year overcome the different initial cost by different annual energy cost.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.99-102
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• 2008

The growth of domestic energy demand is rapidly increased for the industrialization and the improvement of the living standards. It is also recognised that the importance of the use of environmentally friendly energy and high efficient equipment. Ground Source heat pumps(GSHP) using earth as heat source or sink are outstanding environmentally friendly energy systems which have high thermal efficiency when compared to conventional heating and cooling system. So government employs a policy and increase investment for expanding renewable energy market volume. Especially is established a system for obligatory usage of renewable energy to achieve 5% renewable energy diffusion rate by 2011. And the market demand for the ground source heat pump is rapidly growing due to its strong advantages. However domestic situation usually have been depended on the import of ground source heat pumps. In this paper, the results of development of a ground source heat pump using refrigerant R410A are reported.

• 제어로봇시스템학회논문지
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• 제12권6호
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• pp.539-546
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• 2006

The Air Quality Sensor(AQS), located near the fresh air inlet, serves to reduce the amount of pollution entering the vehicle cabin through the HVAC(heating, ventilating, and air conditioning) system by sending a signal to close the fresh air inlet door/ventilation flap when the vehicle enters a high pollution area. The sensor module which includes two independent sensing elements for responding to diesel and gasoline exhaust gases, and temperature sensor and humidity sensor was designed for intelligent AQS in automobile. With this sensor module, AVR microcontroller was designed with back propagation neural network to a powerful gas/vapor pattern recognition when the motor vehicles pass a pollution area. Momentum back propagation algorithm was used in this study instead of normal backpropagation to reduce the teaming time of neural network. The signal from neural network was modified to control the inlet of automobile and display the result or alarm the situation in this study. One chip microcontroller, ATmega 128L(ATmega Ltd., USA) was used for the control and display. And our developed system can intelligently reduce the malfunction of AQS from the dampness of air or dense fog with the backpropagation neural network and the input sensor module with four sensing elements such as reducing gas sensing element, oxidizing gas sensing element, temperature sensing element and humidity sensing element.