• 한국소음진동공학회논문집
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• 제14권11호
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• pp.1059-1065
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• 2004

In this paper, the dynamic characteristic analysis of carriage structure supported by air bearings were performed. Toward this end, the characteristics of air bearing were numerically analyzed to estimate the stiffness of the air bearing and the clearance between air bearing and guide surface. The modal analysis of the carriage structure was performed by using finite element method, and the experimental modal analysis was also performed to validate the finite element model, where rigid body modes were compared to validate the stiffness of the air bearings. From the results, the air spring stiffness can be estimated within the range of acceptable accuracy under any pressure and clearance condition.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.462-466
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• 2003

This study was conducted to examine the potential of biosparging process in removing diesel contaminated soil and groundwater. The experiment was carried out lab-scale biosparging reactor and the biodegradation rate of diesel was evaluated as function of air injection rate and pattern. When renter was operated as air injection rate of 1000$m\ell$/min and pulsed air injection(15min pulse, 15min downtime), DO concentration in the renter was higher than another operating condition. The evidence for biodegradation of diesel was the $O_2$ utilization and $CO_2$ product following the cessation of sparging. Especially, air injection rate of 2000$m\ell$/min and pulsed air injection(15min pulse, 15min downtime) enhanced the diesel biodegradation during the operating. After 120day, the biodegradation rate of diesel was decreased as the lack of carbon source.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1107-1114
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• 2003

In this thesis, the dynamic characteristic analysis of carriage structure supported by air bearings were peformed. Toward this end, the characteristics of air bearing were numerically analyzed to estimate the stiffness of the air bearing and the clearance between air bearing and guide surface. The modal analysis of the carriage structure was peformed by using finite element method, and the experimental modal analysis was also performed to validate the finite element model, where rigid body modes were compared to validate the stiffness of the air bearings. From the results, the air spring stiffness can be estimated within the range of acceptable accuracy under any pressure and clearance condition.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.589-593
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• 2007

In the mechanical ventilation system, it is a fundamental condition to distribute the air equally to the each room. In this study, distribution performance of the air distributor which generally connected to a circular duct was investigated by simulation and experiment. In the first CFD analysis, maximum air flow rate deviation was an 63% in the air distributor model. After numbers of model modification and simulation, maximum flow rate deviation was reduced to 19% in the final simulation model. An air distributor which used in the experiment was produced by using data obtained from the final analysis. When experimental result was compared with analysis result, there was a deviation difference as much as 9%.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.53.5-53
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• 2001

In continuous galvanizing process at steel making plant, coating weight on the surface of strip that pass through air knife is controlled by the pressure at the chamber of air knife and the gap between the nozzle of air knife and strip. The pressure can be easily measured and controlled. But it is difficult to measure the distance between Air knife nozzle and strip, and also difficult to decide how much distance air knife move. Because, the gap between nozzle and strip varies with the height of air knife, intermesh of stabilizing roll and welding of strips that have different thickness. In this research, we developed a gap sensor that can measure the relative distance between Air knife nozzle and strip. And several tests are performed to find optimal condition for application at real plant. We performed test in which the possibility of the sensor to apply ...

• 대한기계학회논문집B
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• 제41권10호
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• pp.693-698
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• 2017

원통형 리튬이온 배터리를 이용한 배터리 팩의 냉각을 위한 해석을 수행하였다. 파우치형에 비해서 원통형 셀을 이용한 배터리 팩은 저렴하면서 신뢰도가 우수한 것으로 알려져 있다. 단지 부피가 파우치 타입에 비해서 크고 디자인적으로 제약이 있다라는 단점을 가지고 있다. 본 논문에서는 18650 배터리를 이용한 배터리팩의 냉각성능을 해석을 통하여 예측하였다. 배터리팩의 온도 안정성은 자동차용 배터리 팩에서 가장 중요한 부분이기 때문이다. 해석을 수행하기 전에 발열 시험을 수행하였으며 열화상 카메라를 이용하여 온도를 측정하고 해석을 통해서 이에 해당하는 발열량 값을 예측하였다. 이를 바탕으로 배터리 팩의 자연대류와 강제대류 해석을 진행하였으며 각각의 냉각 성능을 비교하였다. 배터리 셀을 직접 냉각하는 직접냉각 방식, 배터리 케이스 상하면을 냉각하는 방식, 배터리 케이스 상하면에 공기 통로를 설치하는 세 가지 방식에 대해서 냉각 성능을 비교하였고, 공기채널 방식이 안정성과 냉각성능 면에서 우수함을 해석을 통하여 입증하였다.

• 공업화학
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• 제24권4호
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• pp.350-356
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• 2013

페로니켈 제조공정 슬래그를 대상으로 aging 조건에 따른 용출 특성을 연구하였다. 시료의 주성분은 54.05% $SiO_2$, 34.33% MgO, and 5.51% $Fe_2O_3$이었다. 주 결정구조는 Enstatite [(Mg, $Fe^{2+}$)$SiO_3$]이었다. 페로니켈 슬래그를 침수, 공기유입 침수, 습윤공기 조건에서 3개월간 aging 처리하였다. 습윤공기 aging 조건이 가장 효과적이었다. 습윤공기 aging 처리한 슬래그에서 마그네슘과 철의 침출율이 각각 80.0%, 75.1%로 가장 우수하였다. XRD, SEM 분석결과 습윤공기 aging 처리한 슬래그에서 결정성분의 파괴정도가 가장 크게 나타났다.

• 설비공학논문집
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• 제16권11호
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• pp.1051-1059
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• 2004

Two phase thermosyphone loop for electronics cooling are designed and manufactured to test its performance under the partial load and low environment temperature conditions. The thermosyphone device has six evaporators connected parallel for the purpose of cooling six power amplifier units (PAU) independently. The heater modules for simulating PAUs are adhered with thermal pad to the evaporator plates to reduce the contact resistance. There are unbalanced distributions of liquid refrigerant in the differently heated evaporators due to the vapor pressure difference. To reduce the vapor pressure differences caused by partial heating, two evaporators are connected each other using the copper tube. The pressure regulation tube successfully reduces these unbalances and it is good candidates for a field distributed systems. Under the low environment temperature operating condition, such as $-30^{\circ}C$, there may be unexpected subcooling in condenser. It leads the very low saturation pressure, and under this condition there exists explosive boiling in evaporator. The abrupt pressure rise due to the explosive boiling inhibits the supplement of liquid refrigerant to the evaporator for continuous cooling. Finally the cooling cycle will be broken. For the normal circulation of refrigerant there may be an optimum cooling air flow rate in condenser to adjust the given heat load.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.490-498
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• 2010

K사의 방진고무 사출성형에 있어서 애로사항인 토크로드부시(torque rod bush)의 캐비티 가장자리(edge) 구간에서의 에어트랩(air-trap) 발생 및 다이내믹 댐퍼(dynamic damper)에 있어서 사출시 미성형(short shot) 발생 등의 문제점을 해결하기 위하여, 상용 CAE 프로그램인 MOLDFLOW(Ver. 5.2)를 이용한 전산모사를 수행하여 적정금형설계를 도출하고 적정작업조건을 구축하였다. 그 결과 방진고무 중에서 토크로드부시의 사출성형에서의 에어트랩 발생 등의 공정문제를 최적 캐비티 가장자리 경사각 및 게이트 수를 조절함으로써 캐비티 가장자리에서의 유동선단(flow-front)의 유동정체를 방지하고 유동을 원활하게 하여 해결하였다. 한편 다이내믹 댐퍼의 사출시 충전(filling) 단계에서의 캐비티 비충전으로 인한 미성형 불량은 에어벤트(air-vent) 구를 에어트랩 발생 빈도가 매우 높은 유동선단 상향류와 하향류의 두 흐름이 만나는 지점에 설치함으로써 미성형 불량을 해결하였다. 또한 게이트 위치를 댐퍼 상단에서 중단으로 변경하거나 게이트 수를 증가시킨 경우에 미성형 불량이 K사의 경우보다 개선되었다.