• 한국자동차공학회논문집
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• 제1권1호
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• pp.22-31
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• 1993

Spark-ignition engine knock is affected by engine operating conditions such as engine speed, spark timing and intake air temperature. In this study the effect of intake air temperature on knock characteristics was studied experimentally using a 4-cylinder carburetor spark-ignition engine. The cylinder pressure data at 2000rpm were taken for intake air temperature range of $30^{\circ}C$ to $80^{\circ}C$ with $10^{\circ}C$ interval. And 80 consecutive cycles were taken at each experimental condition. As the same spark timing, as the intake air temperature increased by $50^{\circ}C$, the mean knock intensity increased about 20kPa. This effect corresponds to that of spark timing advance of 3 crank angle degrees.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.93-94
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• 2008

• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.740-750
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• 2003

It has been observed that the cooling capacity of an impinging water jet is affected by the seasonal conditions in large-scale steel manufacturing processes. To confirm this phenomenon, cooling experiments utilizing a hot steel plate cooled by a laminar jet were conducted for two initial ambient air temperatures (10$^{\circ}C$ and 40$^{\circ}C$) in a closed chamber, performing an inverse heat conduction method for quantitative comparison. This study reveals that the cooling capacity at an air temperature of 10$^{\circ}C$ is lower than the heat extracted at 40$^{\circ}C$. The amount of total extracted heat at 10$^{\circ}C$ is 15% less than at 40$^{\circ}C$ , These results Indicate the quantity of water vapor, absorbed until saturation, affects the mechanism of boiling heat transfer.

• 설비공학논문집
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• 제17권8호
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• pp.722-728
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• 2005

The present paper deals with heating energy estimation in Korean-style apartments, paying special attention to the effect of room condition settings. Two types of heating modes are considered: continuous single-zone and scheduled multi-zone. In the latter, zones during unoccupied periods remain unconditioned. Also analyzed are sensitivities in heating energy with respect to the air change rate and the set temperature. The energy use is estimated with TRNSYS 15, a dynamic load calculation program. Heating energy for the actual residential condition (1.0 ACH and $24^{\circ}C$) appears to be nearly the same as that for a typical design standard (1.5 ACH and $20^{\circ}C$). The air change rate affects heating energy as sensitive]y as the set temperature. For all the simulated cases, the scheduled multi-zone heating mode is more energy-efficient than the continuous single-zone. Heating energy depends appreciably on the shading factor. It is expected that considerable heating energy for apartment houses can be saved by employing a multi-zone mode along with appropriate control devices.

• 한국산학기술학회논문지
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• 제19권11호
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• pp.326-331
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• 2018

최근 들어 건물이나 데이터 센터의 공조에 기화식 가습기가 널리 사용된다. 일반적으로 가습 효율은 외기 조건에 관계없이 동일하게 적용된다. 하지만 이 부분에 대해서는 확인이 필요하다. 본 연구에서는 일반 건물과 데이터 센터의 설계 온습도 조건에서 일련의 실험을 수행하고 상기 가정이 적절한지를 판단하였다. 실험에 사용된 소자는 cellulose/PET 재질로 깊이 100mm, 200 mm, 300 mm 세 종류이고 전방 풍속 1.0 m/s에서 4.5 m/s 사이에서 수행되었다. 실험 결과 가습 효율은 외기 조건에 따라 차이가 났다. 데이터 센터 ($25^{\circ}C$ DBT, $15^{\circ}C$ WBT) 조건에서 건물 공조 ($35^{\circ}C$ DBT, $21^{\circ}C$ WBT) 조건보다 크게 나타났는데 그 이유는 입구 영역에서 수분 전달 성능의 차이 때문이다. 심지어 건물 공조 조건에서는 입구 영역에서 제습이 일어났다. 또한 공급수 온도가 외기 공기의 습구온도에 근접할수록 가습 효율이 증가함을 확인하였다. 따라서 가습소자의 성능을 적절히 예측하기 위해서는 입구 영역에 대한 해석 모델이 포함되어야 한다. 한편 소자의 두께가 100 mm에서 200 mm로 되면 가습효율이 29% 증가하고 300 mm가 되면 42% 증가한다. 하지만 압력 손실도 47%, 86% 증가한다.

• The Korean Journal of Ecology
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• 제23권4호
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• pp.293-298
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• 2000

To study the effect of global warming on the growth of plants and plant populations throughout their life cycle under a field-like condition, we constructed a Temperature Gradient Chamber (TGC) in Tsukuba, Japan. The chamber had slender shape : 30 m long. 3 m wide, and 2.5 m high. That satisfactory performance was confirmed by a test throughout all seasons in 1998: the projected global warming condition in the near future was simulated. That is, independent of a great daily or seasonal change in ambient meteorological conditions, air temperatures at the air outlet were warmed 5$^{\circ}C$ higher than those at the ambient (the annual mean was 14.3$^{\circ}C$) with precision of ${\pm}$0.2$^{\circ}C$ (the annual means were 19.2$^{\circ}C$) with a rising rate of approximately 1$^{\circ}C$ every 5 m. This chamber will enable us to study the effects of global warming on growth of plants and plant populations because their abilities to control air temperature are excellent. TGC is expected that it would be utilized for studying the effect of global warming on plant growth under natural weather conditions.

• 방사성폐기물학회지
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• 제2권1호
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• pp.13-22
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• 2004

This study presents the thermal analyses of a spent fuel dry storage cask under normal and off-normal conditions. The environmental temperature is assumed to be 15 $^{\circ}C$ under the normal condition. The off-normal condition has an environmental temperature of 38 $^{\circ}C$. An additional off-normal condition is considered as a partial blockage of the air inlet ducts. Two of the four air inlet ducts are assumed to be completely blocked. The significant thermal design feature of the storage cask is the air flow path used to remove the decay heat from the spent fuel. Natural circulation of the air inside the cask allows the concrete and fuel cladding temperatures to be maintained below the allowable values. The finite volume computational fluid dynamics code FLUENT was used for the thermal analysis. The maximum temperatures of the fuel rod and concrete overpack were lower than the allowable values under the normal and off-normal conditions.

• 농업생명과학연구
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• 제43권3호
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• pp.27-34
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• 2009

녹차 잎 1.5 g에 증류수 100 mL을 가하여 $75^{\circ}C$에서 5분 동안 추출하여 녹차 음료를 제조하였다. 저장 조건을 달리하여 A 녹차 음료 (빛을 인위적으로 차단하지 않음, 자연 상태의 대기 조건, 비타민 C 무첨가), B 녹차 음료 (빛을 알루미늄 호일로 감싸서 차단함, 질소를 불어넣어 자연 대기를 질소로 치환하였음, 비타민 C 30 mg/100 mL 첨가), C 녹차 음료 (빛을 알루미늄 호일로 감싸서 차단함, 질소를 불어넣어 자연 대기를 질소로 치환하였음, 비타민 C 무첨가)로 구분하여 $4^{\circ}C$에서 28일간 저장한 후, 유용 성분을 분석하였다. 총페놀 함량의 경우 저장 초기에 비하여 저장 28일 후 A 녹차 음료는 71.50%, B 녹차 음료는 73.88%, C 녹차 음료는 75.07%로 감소하였다. DPPH 라디컬 소거능은 저장 초기에 비하여 A 녹차 음료는 87.87%, B 녹차 음료는 92.93%, C 녹차 음료는 88.39%이었다. 녹차의 유용 카테킨인 epigallocatechin gallate (EGCG)는 28일간 저장 후에 A 녹차 음료는 130.61%, B 녹차 음료는 136.47%, C 녹차 음료는 4.34%이었다. 이상의 결과는 녹차의 저장 조건이 녹차 음료의 성분에 영향을 미치며, 빛, 질소 치환, 비타민 C가 매우 중요함을 시사하였다.

• 한국분무공학회지
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• 제9권4호
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• pp.17-23
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• 2004

Spray characteristics of a twin-hole air shrouded nonle designed for gasoline injectors was investigated by using laser diffraction particle analyzer (LDPA) and tomography reconstruction- A confined spray chamber which is optically accessible through a pair of glass windows was made to simulate the fuel injection condition in intake manifold of gasoline engine. The measurement was applied to the twin hole injector with and without an air shroud. It demonstrates that for the case with an air shroud, fine atomization is achieved and there exists a large number of fine droplets between the region of the main spray streams, which conforms with the spray visualization. The drop size distribution was investigated as a function of elapse time after fuel injection. The distribution was greatly affected by the measurement position from the injector exit. Also, the spatially resolved spray volume fraction and Sauter Mean Diameter (SMD) from line-of-sight data of the LDPA are tomographically reconstructed by Convolution Fourier transformation under the steady injection condition.

• 한국안전학회지
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• 제28권1호
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• pp.52-56
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• 2013

The purpose of this study is to evaluate the influence of form-oil on steam-cured concrete surface condition. Based, viscosity(high, medium, low) and flash point($26^{\circ}C$, $70^{\circ}C$) of form oil were considered as test variables. The digital image process method was applied for the extraction of air-void area from concrete surface. Test result showed that oil-based form oil reduced air-void by approximately 46% compared to water-based form oil, and the higher the viscosity was, the smaller air-void rate was. In addition, it was conformed that flash point of form oil had a considerable influence on the surface condition of steam-cured concrete.