• International Journal of Air-Conditioning and Refrigeration
• /
• 제13권4호
• /
• pp.175-183
• /
• 2005

The present study has been conducted for manufacturing MPCM (microencapsulated phase change material) slurry with in-situ polymerization and proving their applicabilities for cooling system. The tetradecane as a core material of MPCM is coated with melamine. The produced capsules are observed by the optical microscope and SEM for superficial shapes and analysed their properties by DSC and particle size distribution by FA particle analyzer. It is found that narrow size distribution in 1 to $10{\mu}m$ is resulted in $5{\mu}m$ of average diameter and $9^{\circ}C$ melting temperature. The durability of MPCM capsules is tested with various types of pumps such as centrifugal, peristaltic, and mono. For the centrifugal and peristaltic pumps the breakage fraction of the capsules is resulted within $6\%$ during 10,000 cycles, while the mono is over $8\%$. The cooling system, which has adopted MPCM slurry as a medium for transporting cold thermal energy, is designed to investigate the performance of newly developed coolant. The discharging times of cold energy in circulating 10 and $20wt\%$ MPCM slurry are lasted to 105 and 285 minutes, respectively.

• 한국자동차공학회논문집
• /
• 제18권5호
• /
• pp.31-36
• /
• 2010

SAI(Secondary Air Injection) system has been studied widely as one of the promising countermeasure for reducing HC emission at cold start. In this paper, in order to find out the optimal position of SAI, computational thermal fluid analysis on exhaust system adapted SAI system is performed using commercial 3-D CFD code, CFX. The present results showed that SAI position strongly affected the uniformity of air distribution in front of catalyst. And also through the decision process of optimal position of SAI, new index, uniformity of air distribution($U_{\phi}$) is proposed to define it quantitively. Because $U_{\phi}$ is very simple equation and similar with flow uniformity, it is very easy to figure out the physical meaning and to apply it to practices. Finally, we applied the index $U_{\phi}$ to the decision process of the optimal position of SAI, so that we could get the clear comparison results.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 추계학술대회 논문집
• /
• pp.1316-1321
• /
• 2004

Recently, since demands of energy saving and efficiency for electric railway system have been increased, the study for electrical operation system is needed. Therefore, case study according to increase of energy consumption, investigate the actual conditions of the operation of electric cars and lightings were analyzed. From the results therefore, it is found that the energy consumption of electric car is much more winter than summer, because heating for protect of the air pipe frozen. But the energy consumption of electric equipment of station office is much more summer than winer, the reason for air-conditioner. In future, according to outdoor air temperature and ridership, ,wish to study about system that can operate cold, block heater automatically.

• 설비공학논문집
• /
• 제24권5호
• /
• pp.409-414
• /
• 2012

A theoretical investigation to optimize thermoelectric elements for thermoelectric coolers was performed using a new one-dimensional analytic model. Mathematical expressions for the optimum current and the optimum length of a thermoelectric element, which maximize the coefficient of performance of thermoelectric coolers, were obtained. The optimum current is expressed in terms of the cooling load for a thermoelectric element, the hot and cold side temperatures and thermoelectric properties, but not the length of a thermoelectric element. The optimum current is proportional to the cooling load and decreases as the temperature difference between the hot and cold sides decreases. It is also shown that the optimum length of a thermoelectric element decreases as the cooling load increases.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2008년도 하계학술발표대회 논문집
• /
• pp.1398-1405
• /
• 2008

As the structure, material and construction of building develop continuously, so the recent residential buildings are being large, high-rise and group. High-rise residential buildings consume a lot of energy on supplying cold and hot water. As well, high-rise residential buildings bring on discomfortable use and unexpected conditions on account of faucet outlet pressure rise and the difference of water supply pressure between top floor and bottom floor. Thus, the purpose of this study is to research on using conditions of cold and hot water supply system through survey and field measurement in high-rise residential buildings and to analyze problems.

• 오토저널
• /
• 제14권6호
• /
• pp.67-73
• /
• 1992

This paper describes Hyundai's research and development work on a flexible fuel vehicle (FFV). The work on FFV has been conducted to evaluate its potential as an alternative to the conventional gasoline vehicle. Hyundai FFV described here can be operated on M85, gasoline, or any of their combinations, in which the methanol concentration is measured by an electrostatic type fuel sensor. For that operation, a special FFV ECU(Eletronic Control Unit) has been developed and incorporated in the FFV. The characteristics affecting FFV operation, such as FFV ECU control strategy and injector flow rate, have been investigated and optimized through the experiment. And various development tests have been performed in view of engine performance, durability, cold startability, and exhaust emissions reduction. The exhaust gas aftertreatment system consisting of manifold type catalyst and secondary air injection system shows good emission reduction performance including formaldehyde, and finally, the possibility of the FFVs as the low emission vehicles is evaluated by presenting NMOG(Non-Methane Organic Gases) levels with respect to M0 and M85. With these results, it is concluded that FFV can be a candidate for the low emission vehicles, but more works on its durability improvement is required.

• 원예과학기술지
• /
• 제30권6호
• /
• pp.626-634
• /
• 2012

본 연구에서는 노지재배 포도의 내한성을 증대시킬 수 있는 방법을 모색하고자 간이비가림시설 설치에 따른 식물체의 반응을 조사하였다. 간이비가림시설에서 월동한 식물체의 탄수화물 함량은 노지 처리구에 비해 높았으며, 'Muscat Bailey A'의 줄기보다 '거봉'과 '캠벨얼리' 품종에서 탄수화물의 함량이 높게 나타났다. 노지에 비해 간이비가림시설에서 발아율과 신초의 생장도 양호하였으나 방충망, 차광막을 처리한 구에서는 유의차가 나타나지 않았다. 포도 잿빛곰팡이병의 발생은 간이비가림시설에서 발생이 적었다. Stilbene 화합물 함량은 노지보다 간이비가림 처리구에서 함량이 약간 더 높게 나타났으며 가장 많이 함유된 stilbene은 배당체 형태인 t-piceid였으며, resveratrol, piceatannol, c-piceid에 비해 상당히 고함량을 나타내었다. Chalcone isomerase, manganese superoxide dismutase, proline rich protein 2, temperature induced lipocalin의 transcripts는 시간이 지날수록 유전자의 발현량이 더 많이 축적되었고, 대체적으로 간이비가림시설의 삽수에서 저온 스트레스에 더 강하게 발현되었다. 처리구별 온도차이는 없었으나 노지에 비해 간이비가림시설에서 풍속이 크게 감소하였으며, 간이비가림시설 내에서 차광막을 설치한 경우 풍속의 감소효과가 현저하게 나타났다. 겨울철의 간이비가림시설과 방충망을 설치함으로써 극저온에 의한 포도나무의 저온피해를 줄일 수 있을 것이다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2002년도 ICCAS
• /
• pp.66.5-66
• /
• 2002

Flatness of strip at aluminum cold rolling is one of the important quality parameters of rolled products. The reasons for this are perhaps obvious: for many of the end uses, subsequent processing requires a flat product poor flatness on-line can lead to reduced running speeds and hence to lower production levels. Amongst the reasons for lower running speeds is the increased risk of strip breaks. The Alcan Ulsan plant developed an automatic flatness control system on conventional four high mills for a year. This system compose of three parts as Intel RMX 3.3 operating system, advanced techniques, and flatness error analysis system. Strip flatness be measured by air bearing roll, passing the s...

• 대한기계학회논문집
• /
• 제19권4호
• /
• pp.1116-1124
• /
• 1995

Using a cycle simulation program developed by authors, some thermodynamic characteristics of an aircraft ECS under various operating conditions are studied. When the inlet temperature of cockpit and avionics bay, as well as ram air flow, is held fixed, the effect of the change of regulated bleed pressure is examined. When the regulated bleed pressure, and the cockpit and avionics bay inlet temperature are fixed, the effect of the change of ram air flow is also investigated.

• 한국초전도ㆍ저온공학회논문지
• /
• 제11권1호
• /
• pp.64-68
• /
• 2009

To keep the superconducting (SC) magnet coils of KSTAR at proper operating conditions, not only the coils but also other cold components, such as thermal shields (TS), magnet structures, SC bus-lines (BL), and current leads (CL) must be maintained at their respective cryogenic temperatures. A helium refrigeration system (HRS) with an exergetic equivalent cooling power of 9kW at 4.5K without liquid nitrogen $(LN_2)$ pre-cooling has been manufactured and installed for such purposes. In this proceeding, we will present the commissioning and initial operation results of the KSTAR HRS. Circuits which can simulate the thermal loads and pressure drops corresponding to the cooling channels of each cold component of KSTAR have been integrated into the helium distribution system of the HRS. Using those circuits, the performance and the capability of the HRS, to fulfill the mission of establishing the appropriate operating condition for the KSTAR SC magnet coils, have been successfully demonstrated.