• 대한기계학회논문집B
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• 제36권5호
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• pp.563-569
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• 2012

추력 30톤급 액체로켓엔진에 대한 에너지 밸런스 해석을 수행하였다. 추력-연소압 관계, 추력-추진 제유량 관계 및 연소압-연료펌프상승 관계를 문헌에 공개된 실존 로켓엔진에 대한 데이터베이스와 비교하였다. 참고문헌의 분류에 따른 구형 설계보다 연소압이 높으며 이는 고성능 지향적이라는 의미를 가진다. 추력-추진제유량 비율은 기존엔진과 유사한 수준이었으며 이는 통상 수준의 비추력 성능을 의미한다. 연소압을 감안한 연료펌프의 압력상승은 높은 수준이며 이는 본 연구의 고려 대상인 엔진이 지상시험용으로서 차압설정이 최적화되지 않았기 때문이다.

• Animal Bioscience
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• 제37권3호
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• pp.522-535
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• 2024

Objective: Transition period is considered from 3 weeks prepartum to 3 weeks postpartum, characterized with dramatic events (endocrine, metabolic, and physiological) leading to occurrence of production diseases (negative energy balance/ketosis, milk fever etc). The objectives of our study were to analyze the periodic concentration of serum beta-hydroxy butyric acid (BHBA), glucose and oxidative markers along with identification, and validation of the putative markers of negative energy balance in buffaloes using in-silico and quantitative real time-polymerase chain reaction (qRT-PCR) assay. Methods: Out of 20 potential markers of ketosis identified by in-silico analysis, two were selected and analyzed by qRT-PCR technique (upregulated; acetyl serotonin o-methyl transferase like and down regulated; guanylate cyclase activator 1B). Additional two sets of genes (carnitine palmotyl transferase A; upregulated and Insulin growth factor; downregulated) that have a role of hepatic fatty acid oxidation to maintain energy demands via gluconeogenesis were also validated. Extracted cDNA (complementary deoxyribonucleic acid) from the blood of the buffaloes were used for validation of selected genes via qRTPCR. Concentrations of BHBA, glucose and oxidative stress markers were identified with their respective optimized protocols. Results: The analysis of qRT-PCR gave similar trends as shown by in-silico analysis throughout the transition period. Significant changes (p<0.05) in the levels of BHBA, glucose and oxidative stress markers throughout this period were observed. This study provides validation from in-silico and qRT-PCR assays for potential markers to be used for earliest diagnosis of negative energy balance in buffaloes. Conclusion: Apart from conventional diagnostic methods, this study improves the understanding of putative biomarkers at the molecular level which helps to unfold their role in normal immune function, fat synthesis/metabolism and oxidative stress pathways. Therefore, provides an opportunity to discover more accurate and sensitive diagnostic aids.

• 한국자동차공학회논문집
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• 제7권8호
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• pp.7-16
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• 1999

To maintain thereasonable temperature in the engines is very important to keep the steady combustion state of engine and to prevent increasing of oil consumption , deteriorating of lubricant, shortening of the life time of engine and decreasing of material strength. The method of energy balance for divided elements of radiator and engine-oil cooler is considered to analyse the performance of radiator and engine-oil cooler. The data obtained by engine test and vehicle cooling tunnel test are applied to program for calculation of radiator outlet temperature. As a result, data obtained by numerical analysis agree well with those by experiments. And thus, it is concluded that this simulation program is available in developing the cooling system for a new car.

• 대한정형도수물리치료학회지
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• 제27권2호
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• pp.55-67
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• 2021

Background: This study aimed to use the muscle energy technique (MET) with total knee replacement (TKR) during the chronic phase in a clinical setting and confirm its effects on the knee extensor strength and ROM, balance, and walking ability. Methods: A total of 20 female patients who underwent TKR 1~4 years ago were assigned to two groups (Control: Q setting exercise+general physical therapy, n=10; Exp: MET+general physical therapy, n=10). Interventions were performed three times a week for 4 weeks. The strength of the knee extensor was evaluated using an aneroid sphygmomanometer, and ROM was evaluated using degrees at the end range on active knee flexion. The main balance outcomes were evaluated using two standard scale (TSS) and timed up and go (TUG) test, whereas the walking ability was evaluated using the 10 meter walk test (10MWT). Results: Analysis showed that both groups had significant increases in strength, ROM, TSS, TUG, and 10MWT. Differences in all variables were significant between the control and Exp groups at the post-intervention evaluation (p<.05). However, no significant difference was observed in strength and TUG. Conclusion: Results of this study demonstrated that MET would help improve the strength, ROM, balance, and walking ability of patients with chronic TKR who want to enhance their abilities and performance in activities of daily living.

• 한국산림과학회지
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• 제98권6호
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• pp.799-805
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• 2009

산림바이오매스 자원의 소규모 난방에너지 이용을 위한 시스템 구축에 있어 목재칩의 연료 활용을 목적으로 목재칩 연료 생산단계에서의 비용분석과 에너지수지를 분석을 통해 산림바이오매스 자원의 에너지 이용 가능성을 검토하였다. 집재기계와 경사도별로 구분되어진 목재칩 생산 시스템에서 1 kg의 칩을 생산하기 위해 소요되는 총 생산비용은 195.45~210.54원/kg으로 산출되었으며, 에너지 투입률(%)분석에서는 26.58~27.38%의 에너지 투입률을 나타내었다. 경사도에 따른 에너지 투입률의 변화는 크지 않았으며, 생산비용의 경우와는 달리 타워야더 시스템인 시나리오 B가 트랙터 집재 시스템인 시나리오 A보다 에너지 투입률이 낮은 것으로 나타났다.

• 에너지공학
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• 제2권3호
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• pp.276-284
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• 1993

분류층 가스화기를 대상으로하여 석탄가스화 복합발전 시스템을 위한 가스화반응 모델링을 수행하였다. 가스화기 내에서의 가스화반응은 화학평형상태에 있다고 가정하여 Gibbs 자유에너지 최소화법을 이용하였다. 물질수지와 열수지를 동시에 고려한 모델링 결과와 실제 가스화기 실험자료를 비교하여 모델의 신뢰성을 확인하였다. 이를 토대로 가스화기에 공급되는 산화제의 양이 평형조성에 미치는 영향과 가스화기의 온도, 그리고 석탄종류가 가스화반응에 미치는 영향에 대해 알아보았다.

• 한국수소및신에너지학회논문집
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• 제30권5호
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• pp.385-394
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• 2019

The analysis of temperature behavior of a hydrogen tank during refueling is of significance to clarify the safety of the compressed hydrogen storage in vehicles since the temperature at a tank rises with inflow of hydrogen. A mass balance and an energy balance were combined to obtain analytical model for temperature change during the hydrogen refueling. The equation was coupled to Peng-Robinson-Gasem (PRG) equation of state (EOS) for hydrogen. The PRG EOS was adopted after comparison with other four different cubic EOSs. A parameter of the model was determined to fit data from experiments of various inlet flow rates and temperatures. The temperature and pressure change with refueling time were obtained by the developed model. The calculation results revealed that the extent of precooling was more effective than the flow rate control.

• 항공우주기술
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• 제9권2호
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• pp.176-184
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• 2010

지구 저궤도 위성의 임무 운용 시 전력 시스템을 안전하고 운용하고 에너지 균형을 만족하는 임무를 설계하기 위해 계획된 임무에 대한 전력 파라미터를 예측해야 한다. 이 논문에서는 다양한 미션 프로파일에 대해 위성의 생성 전력, 소모 전력, 배터리 방전 정도(Depth of Discharge, 이하 DoD), 버스 전압, 충/방전 전류 등을 예측함으로써 미션의 유효성 및 에너지 균형을 검증하기 위한 전력 시뮬레이터를 제안한다. 제안된 전력 시뮬레이터에는 인공위성의 생성 전력을 모사하기 위해 태양전지판(Solar Array, 이하 SA)의 모델, SAR (Solar Array Regulator)의 3가지 동작 모드를 구현하였다. 또한 소모 전력을 모사하기 위해 버스 및 탑재체의 각 유닛 별 소모 전력, Unit on/off configuration, 탑재체 운용 모드 등을 고려하였다. 버스 전압 및 충/방전 전류를 예측하기 위해 배터리 및 주변 회로를 모델링하고 임의의 DoD, 충방전 전류에 대해 배터리 전압 및 버스 전압을 예측한다. 구현된 전력 시뮬레이터를 이용해 에너지 균형을 분석하고 임무 계획의 적합성을 쉽게 판단할 수 있다.

• 한국식품조리과학회지
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• 제6권4호통권13호
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• pp.41-50
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• 1990

This study aimed to investigate the change in food balance and dietary patterns, caused by the growth of per capita GNP during $1962{\sim}1987$. For the purpose of this analysis, ordinary least square (OLS) was adopted. Per capita GNP was independent variable and the other factors dependent variables. The other factors included Engel coefficient, food supply, energy supply, nutrient intake and the ratio of self-supply of food. The result revealed that the some variables have (+) correlation, the some variables (-) correlation and the other variables no correlation with per capita GNP. If forecasting models are designed with these results, it will be helpful for national health and nutrition, food balance and disease prevention.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권2호
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• pp.22-28
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• 2016

In order to evaluate landfill stabilization based on organic carbon, stoichiometric analysis and a biological methane potential (BMP) test based on modeling were performed at the 2^nd Sudokwon Landfill Site. Mass balance analysis through a BMP test proved to be more adaptable for evaluation, and it showed that 28.9% of landfill organic carbon was expected to remain by 2046, 30 years after landfill closure. The organic carbon ratio of total landfill waste for 2046 is forecasted as 2.9% in demolition waste and 5.1% in household waste, and, if one were to consider plastic as an organic waste, the ratios would increase to 15.9% and 28.3%, respectively. Therefore, it seems that organic matter biodegradation facilitating measures such as bioreactor landfill technology and preemptive recovery of combustible waste are necessary to shorten post closure management periods and to meet the landfill stabilization guidelines more safely.