• 한국자동차공학회논문집
• /
• 제4권1호
• /
• pp.147-154
• /
• 1996

An one-zone heat release analysis was studied for a 6 cylinder direct injetction compressionignition engine. The heat transfer constants in this anlysis were calibrated to match the measured fuel energy at 1,000 rpm full load, which was the fuel mass multiplied by the fuel's heating value. The integrated gross heat release values were close to the measured fuel energy at various full load operating conditions. The combustion inefficiency from this calculation was proportional to the smoke of exhaust gas.

• Nuclear Engineering and Technology
• /
• 제48권3호
• /
• pp.673-683
• /
• 2016

This paper analyzes the accuracy of the methods used in calibrating the thermal power of Nigeria Research Reactor-1 (NIRR-1), a low-power miniature neutron source reactor located at the Centre for Energy Research and Training, Ahmadu Bello University, Zaria, Nigeria. The calibration was performed at three different power levels: low power (3.6 kW), half power (15 kW), and full power (30 kW). Two methods were used in the calibration, namely, slope and heat balance methods. The thermal power obtained by the heat balance method at low power, half power, and full power was $3.7{\pm}0.2kW$, $15.2{\pm}1.2kW$, and $30.7{\pm}2.5kW$, respectively. The thermal power obtained by the slope method at half power and full power was $15.8{\pm}0.7kW$ and $30.2{\pm}1.5kW$, respectively. It was observed that the slope method is more accurate with deviations of 4% and 5% for calibrations at half and full power, respectively, although the linear fit (slope method) on average temperature-rising rates during the thermal power calibration procedure at low power (3.6 kW) is not fitting. As such, the slope method of power calibration is not suitable at lower power for NIRR-1.

• 생물환경조절학회지
• /
• 제9권4호
• /
• pp.201-206
• /
• 2000

여름철 고온기에 시설 이용율을 높이고 안정적인 생산을 하기 위해서는 고온 극복 시스템의 도입이 필요하며, 이러한 시스템을 도입하기 위하여는 적정 설비용량의 중요하다. 온실의 고온극복방법을 차광환기시스템, 차광환기 패드시스템, 차광환기 포그시스템으로 설정하고, 각 방법별로 시스템의 설계제원 결정을 위한 열평형식을 구성하였으며 현장 실험을 통하여 적용성을 검토하였다. 환기창 단면 풍속을 1분 간격으로 측정하여 유량으로 환산한 값을 환기량의 실측치로 하고 열평형식을 이용하여 계산한 환기량과 비교한 결과 비교적 잘 일치하는 것으로 나타났다. 열평형 모델의 입력변소중 피복재의 열관류이 1% 증가하면 필요환기량은 0.3% 감소하였고, 태양복사에 대한 증발산비(E)의 값이 1% 증가하면 필요환기량은 1.3%나 감소하는 것으로 나타났다. 따라서, E 값의 선택이 매우 중요하며 온실의 환기 및 냉방 설계기준을 설정하기 위해서는 여러 가지 작물의 상태에 따른 E값의 변화를 실측한 자료의 축적을 통해 가이드라인이 제시되어야 할 것으로 판단된다. 온실의 환기 및 냉방 설비 용량 결정을 위한 열평형 모델의 적용성을 검토하기 위하여 6가지의 동일한 조건에 대하여 시뮬레이션한 결과, 필요 공기교환율은 5.1∼7.7%정도, 증발수량은 6.8∼9.3%정도 fan and pad 시스템이 포그시스템에 비하여 큰 것으로 나타났다.

• 한국ITS학회 논문지
• /
• 제14권2호
• /
• pp.30-38
• /
• 2015

본 연구는 동절기 도로관리서비스 향상과 도로의 안전성을 제고하기 위하여, 기존의 입력자료인 기상자료와 더불어 추가적으로 교통자료를 적용하여 노면온도를 예측할 수 있는 모형의 개발을 목표로 하였다. 노면온도 예측모형은 열수지법을 적용하였으며, 모형에서 교통량에 대한 고려는 차량 복사열, 타이어 마찰열로 구성하여 모형화하였다. 이 최종모형과 기상 조건을 기초로 한 초기 모형과 비교하여 노면온도에 미치는 교통량의 영향을 검토하였다. 제3경인고속도로의 실제 관측치과 두 모형에서 계산된 노면온도를 실제 노면온도 관측치와의 비교로 검증하였는데, 관측치와 예측치의 오차인 RMSE은 $1.97^{\circ}C$였다. 관측된 노면온도는 오전 6시부터 일사의 영향을 받아 급격히 상승하여 14시에 최대가되고, 그 후에는 감소한다. 모형 예측값은 관측값보다 오후에는 낮고, 야간에는 높게 나타났다. 이는 오후의 경우는 차량으로 인한 태양 복사열의 차폐, 야간의 경우는 차량열에 의한 열 공급이 주요 원인인 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제19권10호
• /
• pp.1415-1421
• /
• 2006

Proper nutritional management during the dry period is required to prevent metabolic disorders during the time of parturition and for potential increase milk yield during early lactation, especially under the heat of summer. The effect of prepartum diets on partitioning of nitrogen (N), calcium (Ca), phosphorus (P), magnesium (Mg) and potassium (K) during dry period and early lactation in summer was investigated. Nine cows were assigned to two groups and fed either control (group C: four cows) or high concentrate (group H: five cows) diets to meet 110% of their requirements before parturition. The proportion of concentrate in control diet was 35%, and that in the high concentrate diet was 45%. After parturition, all cows were fed the same diets ad libitum during lactation. Balance trials were conducted at 9, 8 and 7 days before parturition and at 12, 13 and 14 days after parturition. Before parturition, dry matter intake (DMI), DM and NFE digestibility in group C tended to be lower than those in group H. The retention of N (p<0.01) and P (p<0.05) in group C during the dry period was significantly lower than those in group H. The retention of Mg in group C during the dry period tended to be lower than in group H. The concentration of plasma NEFA in group C tended to be higher than in group H during dry period. The prepartum diet did not have an apparent effect on DMI and milk yield at 2 weeks after parturition and N, Ca, P, Mg and K balance after parturition.

• 한국수소및신에너지학회논문집
• /
• 제32권5호
• /
• pp.374-387
• /
• 2021

Basic design of 3 MWth chemical looping combustion system for LNG combustion and steam generation was conducted based on the mass and energy balance and the previous reactivity test results of oxygen carrier particles. Process configuration including fast fluidized bed (air reactor), loop seal and bubbling fluidized bed (fuel reactor) was confirmed and their dimensions were determined by mass balance. Then, the external fluidized bed heat exchanger (FBHE) was adopted based on the energy balance to extract heat from the system. The optimum reactor design and operating condition was confirmed with sensitivity analysis by modifying system configuration based on the mass and energy balance.

• 수산해양교육연구
• /
• 제17권2호
• /
• pp.209-217
• /
• 2005

The energy balance of the surface layer of the water (the Yellow Sea, the East China Sea and the East Sea) was examined using satellite data. Variations of the net heat flux were similar to those of the latent heat flux which was more intensive than the sensible heat flux. The sensible heat flux was affected the difference between the sea surface temperature and the air temperature and was less important over the Yellow Sea. The maximum of the latent heat flux occurred in autumn when the air is drier and the wind is stronger. The shortwave radiation flux decreased with the latitude and depended on the cloudiness as the longwave radiation flux does. Annual variations of heat fluxes show that the latent heat flux was more intensive over the East China Sea than the East Sea and the Yellow Sea, while the spatial differences of the other heat fluxes were weak.

• 수산해양기술연구
• /
• 제53권3호
• /
• pp.302-307
• /
• 2017

An electric steam boiler equipped with a condensate recovery system, which stores the condensate generated after using steam in steam washers, steam cookers, steam irons, and steam cleaners in a condensate tank and supplies compressed air to the condensate tank so that the condensate is recovered to the boiler by the pressure of the compressed air, was studied. In the results of this study, the heat energy balance between the quantity of the heat generated by the non-metallic surface heating element and the quantity of the heat absorbed by the water was good in a range of ${\pm}5%$. In addition, the heat transfer rate increased in proportion to the electric power of the surface heating element heater, the waste heat energy was normally recovered by the recovery of the condensate of the steam boiler equipped with the high compression waste heat recovery system, and the recovery rate of the waste heat exhibited 23%.

• 대한한의학회지
• /
• 제42권4호
• /
• pp.185-196
• /
• 2021

Objectives: Many symptoms of cold and heat patterns are related to the thermoregulation of the body. Thus, we aimed to study the association of cold and heat patterns with anthropometry/body composition. Methods: The cold and heat patterns of 2000 individuals aged 30-55 years were evaluated using a self-administered questionnaire. Results: Among the anthropometric and body composition variables, body mass index (-0.37, 0.39) and fat mass index (-0.35, 0.38) had the highest correlation coefficients with the cold and heat pattern scores after adjustment for age and sex in the cold-heat group, while the correlation coefficients were relatively lower in the non-cold-heat group. In the cold-heat group, the most parsimonious model for the cold pattern with the variables selected by the best subset method and Lasso included sex, body mass index, waist-hip ratio, and extracellular water/total body water (adjusted R² = 0.324), and the model for heat pattern additionally included age (adjusted R² = 0.292). Conclusions: The variables related to obesity and water balance were the most useful for predicting cold and heat patterns. Further studies are required to improve the performance of prediction models.

• Korean Chemical Engineering Research
• /
• 제47권5호
• /
• pp.587-592
• /
• 2009

연속조작 기포탑에서 열전달 메카니즘을 검토하기 위하여 열전달 모델과 에너지 소멸속도를 고찰하였다. 기포탑에서 표면갱신이론(Surface renewal theory)에 기초한 비정상상태 열전달모델에 의한 에너지소멸 속도($E_D$)는 기포탑에서 기체와 액체상의 거동에 의한 수력학적인 에너지소멸 속도($P_v$)와 비교하여 매우 작게 나타났다. 이와같은 결과로 표면갱신 이론에 의한 비정상상태 열전달모델에서 사용된 에너지 소멸속도와 기포탑 전체에 대한 수력학적 에너지 수지에 의해 산출된 수력학적 에너지 소멸속도는 산출 메카니즘이 서로 다른 별개의 에너지 소멸속도로 규명되었다. 이들 두 종류의 에너지 소멸속도를 각각 본 연구의 실험 변수인 기체와 액체 유속의 상관식으로 나타내어 완전히 다른 값을 나타냄을 확인하였다.