• 설비공학논문집
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• 제11권2호
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• pp.185-192
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• 1999

Effective thermal conductivities and pressure-drop-related properties of aluminum foam metals have been measured. The effects of porosity and cell size in the aluminum foam metal are investigated in detail. The porosity of the foam metal, considered in the present study, varies from 0.89 to 0.96 and the cell size from 0.65㎜ to 2.5㎜. The effective thermal conductivity is evaluated by comparing the temperature gradient of the foam metal with that of the thermal conductivity-known material. The pressure drop in the foam metal is measured by a highly precise electric manometer while air is flowing through the aluminum foam metal in the channel. The results obtained indicate that the effective thermal conductivities are found to be increased with a decrease in the porosity while the effective thermal conductivities ire little affected by the cell size at a fixed porosity. However, the pressure drop is strongly affected by the cell size as well as the porosity. It is seen that the pressure drop is increased as the cell size becomes smaller, as expected. The minimum pressure drop is obtained in the porosity 0.94 at a fixed cell size. A new correlation of the pressure drop is proposed based on the permeability and Ergun's coefficient for the aluminum foam metal.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1755-1758
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• 2004

Misfiring is often observed during the high temperature quality assurancetest of plasma display panel. This limits the productivity of PDP industry. In this paper, experimental observations on the misfiring at high panel temperature have been performed through time dependent discharge light output and static margin measurement. For the high temperature condition, firing voltage increment is found in both surface and facing discharges. This in turn increases lime lag in address discharge, and results m increment of misfiring probability. In order to reduce this kind of misfiring, a new method that applies automatically different slope of ramp erasing pulse on the common electrode according to temperature variation is proposed. The experimental results show that controlling the slope of ramp erasing pulse is quite effective for compensating temperature-dependent variation of reset and address discharge.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.164-170
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• 2004

Misfiring is often observed during the high temperature quality assurance test of plasma display panel. This limits the productivity of PDP industry. In this paper, experimental observations on the misfiring at high panel temperature have been performed through time dependent discharge light output and static margin measurement. For the high temperature condition, firing voltage increment is found in both surface and facing discharges. This in turn increases time lag in address discharge, and results in increment of misfiring probability. In order to reduce this kind of misfiring, a new method that applies automatically different slope of ramp erasing pulse on the common electrode according to temperature variation is proposed. The experimental results show that controlling the slope of ramp erasing pulse is quite effective for compensating temperature-dependent variation of reset and address discharge.

• 대한기계학회논문집B
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• 제37권3호
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• pp.267-273
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• 2013

막충진재(film fill)를 갖는 냉각탑용 팬의 효율적인 운전조건을 제시하기 위하여, Merkel의 이론을 바탕으로 한 종전의 최적 총연간비용 모델을 사용하여 입구 물온도와 열부하에 따른 최소팬동력을 구하는 프로그램이 새로이 개발되었으며, 냉각탑의 설계 맵이 본 연구로부터 제시되었다. 전형적인 예들을 통하여 본 프로그램의 타당성이 입증되었다. 주어진 열부하에서 이들 팬동력(z 축)-공기질량플럭스(x 축, 최소팬동력 존재)-입구물온도(y 축, 최소팬동력의 최대값 존재)의 3차원 그래프는 말안장 형상으로 나타났다. 최소팬동력들은 열부하에 따라 증가하였다. 따라서, '고온수 유입과 저유량의 공기로 작동' 될 때가 항상 최소팬동력 조건이 아니며, '주어진 입구물온도에 대하여 최소팬동력에 대응하는 최적의 공기질량플럭스가 (열부하와 무관하게) 존재한다'는 사실이 본 연구결과로부터 밝혀졌다.

• 한국의류학회지
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• 제26권6호
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• pp.811-820
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• 2002

The physical responses and subjective sensations of different cleanroom garments were compared in order to discover which cleanroom garment design could minimize pollution of the working environment by dust from the worker, maintain a pleasant microclimate and provide effective thermoregulation. A. Coverall with non-detachable hood, kimono sleeves (front), raglan sleeves (back), raschell net on the bodice B. Coverall with detachable hood, kimono sleeves (front), raglan sleeves (back), raschell net on the bodice C. Separate top with non-detachable hood, kimono sleeves (front), raglan sleeves (back), raschell net on the bodice D. Coverall with non-detachable hood, set-in sleeves, raschell net on the bodice E. Coverall with non-detachable hood, raglan sleeves (back), l00% cotton inner wear (upper body) The results of the experiment were as follows. Because the hood covered the shoulder and the chest areas, the chests temperature of the worker wearing garment E was quite higher than those wearing other garment designs. For fabric that has been coated in order to prevent dust, layered designs should be avoided in order to prevent skin temperature from rising. Compared with layers of underwear, it would be more effective to attach a see-through raschell net which clings to the body. Thermal sensations were also highest in garment E, reinforcing the finding that layered designs should be avoided. Through the experiment, it was found that a new material coverall with a non-detachable hood was effective in minimizing dust, suppressing skin temperature increases, maintaining a superior microclimate and providing pleasant subjective sensations.

• 전자공학회논문지A
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• 제31A권4호
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• pp.77-83
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• 1994

In this paper we numerically approximated the field-effect mobility of a-Si:H TFT. Field-effect mobility, based on the charge-trapping model and new effective capacitance model in our study, used Chebyshev approximation was approximated as the function of gate potential(gate-to-channel voltage). Even though various external factors are changed, this formula can be applied by choosing the characteristic coefficients without any change of the approximation formula corresponding to each operation region. Using new approximated field-effect mobility formula, the dependences of field-effect mobility on materials and thickness of gate insulator, thickness of a-Si bulk, and operation temperature in inverted staggered-electrode a-Si:H TFT were estimated. By this was the usefulness of new approximated mobility formula proved.

• Corrosion Science and Technology
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• 제4권4호
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• pp.147-154
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• 2005

The creep resistance of geogrids is one of the most significant long-term safety characteristics used as the reinforcement in slopes and embankments. The failure of geogrids is defined as creep strain greater than 10%. In this study, the accelerated creep tests were applied to polyester geogrids at various loading levels of 30, 50% of the yield strengths and temperatures using newly designed test equipment. Also, the new test equipment permitted the creep testing at or above glass transition temperature($T_g$) of 75, 80, $85^{\circ}C$. The time-dependent creep behaviors were observed at various temperatures and loading levels. And then the creep curves were shifted and superposed in the time axis by applying time-temperature supposition principles. The shifting factors(AFs) were obtained using WLF equation. In predicting the lifetimes of geogrids, the underlying distribution for failure times were determined based on identification of the failure mechanism. The results confirmed that the failure distribution of geogrids followed Weibull distribution with increasing failure rate and the lifetimes of geogrids were close to 100 years which was required service life in the field with 1.75 of reduction factor of safety. Using the newly designed equipment, the creep test of geogrids was found to be highly accelerated. Furthermore, the time-temperature superposition with the newly designed test equipment was shown to be effective in predicting the lifetimes of geogrids with shorter test times and can be applied to the other geosynthetics.

• 한국세라믹학회지
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• 제22권3호
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• pp.25-28
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• 1985

The new compound $(Ba_{0.5}La_{0.5}) (Mg_0.5}Mo_{0.5})O_3$ is synthesized under the $H_2$-atmosphere and reveals to have a cation ordering between Mg and Mo in cubic lattic of ordered perovskite (a0=8.009(2)$\AA$) and obeys Curie-Weiss law below the room temperature with the effective magnetic moment of 1.60(5) Bohr Magneton.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.181-182
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• 2015

The nonequilibrium plasmas in which electrons have much higher energy compared to heavy species that cannot be represented with single temperature can enhance combustion reaction significantly. Therefore the nonequilibrium plasmas provide new effective mechanism to control combustion to overcome difficulties advanced combustion devices exploiting extreme operating parameters for high efficiency, lower emission.

• 한국의류산업학회지
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• 제2권4호
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• pp.346-352
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• 2000

The purposes of this study are finding out thermophysiological properties throughout wearing experiment with standard cooling vest as well as providing data in order to design and apply more comfortable cooling vest. To do this study, we produced cooling vest newly. 1. Rectal temperature was ascended approximately from $37.2^{\circ}C$ to $38.05^{\circ}C$ in lab, but wearing cooling vest, the temperature was descended 0.2 while wearing developed product compare with existing product. Mean skin temperature which was showed distribution from $32.8{\sim}36.5^{\circ}C$, it was descended $1.0{\sim}1.1^{\circ}C$, while wearing cooling vest and comparing with existing product, wearing developed product was lower $0.5^{\circ}C$. 2. While wearing developed cooling vest, it was found that they had lower tendency than standard cooling vest. Specifically in case of temperature within clothing (chest) $0.2{\sim}2.0^{\circ}C$ in case of humidity within clothing 2~8%RH. Facts from above we confirmed that clothing microclimate had been improved and space was happened between body and garment in order to control. 3. In subjective sensation, standard cooling vest made negative response during experiment period from participants, but new cooling vest was nearing to comfortable area. It was con finned from above conclusions that wearing developed product is more effective in terms of comfort and reduction of heat stress in situation of working in hot environment.