• 한국추진공학회지
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• 제6권4호
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• pp.1-6
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• 2002

소형 연소기의 냉각 유로 설계를 위하여 열전달 및 냉각 유로의 구조해석을 수행하였다. 연소기의 고온가스에서의 열전달에 관한 2차원 해석을 수행하여 연소실 벽으로의 열유속을 예측한 다음 이를 3차원 해석을 위한 열경계 조건으로 적용하였다. 위 방법으로 예측한 열 유속은 기존의 경험식과 비교하여 검증하였으며 냉각수의 유량에 둔감한 것으로 판명되어 냉각 조건이 변화하더라도 동일한 열경계 조건을 사용할 수 있었다. 단일 냉각 유로에 대한 3차원 해석을 수행하여 연소실 벽의 최대온도 변화를 예측하였으며 이는 재사용 연소기 개발에 적용될 것이다. 냉각 유로의 정적 구조 해석을 통해 응력 분포와 구조 안전성을 예측하였다.

• 설비공학논문집
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• 제12권3호
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• pp.258-266
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• 2000

Experimental investigation and cycle simulation of a capacity modulation of a heat pump system using a hydrofluorocarbon (HFC) refrigerant mixture, R32/134a as an alternative to R22, have been done. In the cycle simulation, the refrigeration system was operated by assigning the temperatures of the external heat transfer fluids with the heat exchangers generalized by an average effective temperature difference. Heating capacity, cooling capacity, and coefficient of performance (COP) of the system were investigated at several operating conditions. Experimental apparatus which had a refrigeration part and a composition changing part was built, and the performance of the heat pump system filled with R32/134a mixture was investigated. A gas-liquid separator was used in the experiment to change the composition by collecting the vapor and the liquid Phase separately, The mass fraction of the charged refrigerant in the heat pump system was 40/60 and 70/30 by weight percentage. The composition of the refrigerant with initial composition of 40/60 varied from 29/71 to 41/59 in the refrigeration cycle. For the refrigerant with initial composition of 70/30, the composition varied from 65/35 to 75/25.

• 교육녹색환경연구
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• 제17권3호
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• pp.1-8
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• 2018

기후변화에 따른 지구 생태계의 변화와 에너지 및 자원고갈 등 전 지구적 대응노력이 절실한 상황에서 정부에서는 탈원전 정책 등 적극적인 정책을 수립하여 시행하고 있다. 특히 공공건물 중 적지 않은 비중을 차지하고 있는 학교시설은 학생수가 감소하는 반면 학교수가 증가하고 있으며 에너지사용량 또한 지속적으로 증가하고 있다. 본 연구에서는 학교시설의 설계현황을 분석하여 에너지절약설계의 개선방향을 제시하고자 하였다.

• 한국지열·수열에너지학회논문집
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• 제14권4호
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• pp.1-6
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• 2018

In this study, the energy consumption of the typical floor was compared by the total energy comsumption of the building in highrise building. In gerneral, many researchers are studying on the typical floor in highrise buildings for avoiding complexity in energy simulation. But few papers are studied on energy consumption along the floors. In the model bulding, the energy consumption data were acquired by BEMS system in 2011. According the data, the total net energy consumption was $193.99kWh/m^2$ for all area and the total net energy consumption was $247.61kWh/m^2$ for HVACR area. The total electricity and gas energy are used 47.7% for heating and cooling, 33.5% for lighting and plug, 12.9% for conveyance power and 5.9% for restaurant. In comparison of only ground floor, amount of energy consumption in the lobby is 10%, and 90% of total energy consumption is used in the typical floor. For this result, energy simulation on the typical floor is acceptable for calculating the total energy consumption in the highrise building.

• 한국분무공학회지
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• 제27권2호
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• pp.66-76
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• 2022

This study presents a prediction methodology of transport properties using the methane-based TRAPP (m-TRAPP) method in a wide range of temperature and pressure conditions including both subcritical and supercritical regions, in order to obtain thermo-physical properties for hydrocarbon aviation fuels and their products resulting from endothermic reactions. The viscosity and thermal conductivity are predicted in the temperature range from 300 to 1000 K and the pressure from 0.1 to 5.0 MPa, which includes all of the liquid, gas, and the supercitical regions of representative hydrocarbon fuels. The predicted values are compared with those data obtained from the NIST database. It was demonstrated that the m-TRAPP method can give reasonable predictions of both viscosity and thermal conductivity in the wide range of temperature and pressure conditions studied in this paper. However, there still exists large discrepancy between the current data and established values by NIST, especially for the liquid phase. Compared to the thermal conductivity predictions, the calculated viscosities are in better agreement with the NIST database. In order to consider a wide range of conditions, it is suggested to select an appropriate method through further comparison with another improved prediction methodologies of transport properties.

• 한국추진공학회지
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• 제26권6호
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• pp.10-20
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• 2022

본 연구에서는 케로신 다단연소사이클 엔진용 예연소기를 설계하기 위해, 고압의 산화제 과잉 조건에서 예연소가스를 계산하고 냉각유로에서 극저온 유체의 복합열전달 및 수력 특성을 해석할 수 있는 설계코드를 개발하였다. 사용자 편의성과 범용성을 가진 오픈 소스 라이브러리 Cantera를 활용하였으며, 실제유체의 열역학/전달 상태량을 정확히 계산하기 위해 관련 소스 코드들을 새로 작성하여 Cantera에 추가하였다. 현재 예비설계 중인 100톤급 부스터 엔진용 예연소기에 적용하였으며, CFD 해석결과와 비교를 통해 설계코드로서의 예측 정확도와 활용성을 확인하였다.

• 대한조선학회논문집
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• 제60권3호
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• pp.146-154
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• 2023

Efforts have been made to reduce the greenhouse gas emissions from ships by limiting the energy efficiency index, and net zero CO₂ emission was proposed recently. The most ideal measure to achieve zero emission ship is electrification, and fuel cells are considered as a practical power source of the electrified propulsion system. The electric efficiency in the electrochemical reaction of fuel cells can be achieved up to 60% practically. The remaining energy is converted to heat energy but most of them are dissipated by cooling. In the author's previous research, a hybrid propulsion system utilizing not only electricity but also heat was introduced by combining electric motor and steam turbine. In this article, long term efficiency is evaluated for the introduced hybrid propulsion system by considering a virtual 24,000 TEU class container carrier model. To reflect a more practical operating condition, the actual navigation data of a similar real ship in the real world were collected from automatic identification system data and applied. From the result, the overall efficiency of the hybrid propulsion system is expected to be higher than a conventional electric propulsion fuel cell ship by 30%.

• 수산해양기술연구
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• 제58권4호
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• pp.359-366
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• 2022

In this study, the load fluctuation of the main engine is considered to be a disturbance for the jacket coolant temperature control system of the low-speed two-stroke main diesel engine on the ships. A nonlinear PID temperature control system with satisfactory disturbance rejection performance was designed by rapidly transmitting the load change value to the controller for following the reference set value. The feed-forwarded load fluctuation is considered the set points of the dual loop control system to be changed. Real-coded genetic algorithms were used as an optimization tool to tune the gains for the nonlinear PID controller. ITAE was used as an evaluation function for optimization. For the evaluation function, the engine jacket coolant outlet temperature was considered. As a result of simulating the proposed cascade nonlinear PID control system, it was confirmed that the disturbance caused by the load fluctuation was eliminated with satisfactory performance and that the changed set value was followed.

• 한국수소및신에너지학회논문집
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• 제35권1호
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• pp.97-104
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• 2024

In this study, combustion experiments were conducted to assess engine performance and exhaust gas characteristics using four blends of 1-pentanol and diesel as fuel in a naturally aspirated 4-stroke diesel engine. The blending ratios of 1-pentanol were 5, 10, 15, and 20% by volume. The experiments were carried out under four different engine torque conditions (6, 8, 10, and 12 Nm) while maintaining a constant engine speed of 2,000 rpm for all fuel types. The results showed that the use of 1-pentanol/diesel blended fuel generally led to a decrease in brake thermal efficiency, attributed to the low calorific value of the blend and the cooling effect due to the latent heat of vaporization. Additionally, both brake specific energy consumption and brake specific fuel consumption increased. However, the use of the blended fuel resulted in a general decrease in NOx concentration, a decrease in CO concentration except some conditions, and a reduction in smoke opacity across all conditions.

• 청정기술
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• 제20권2호
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• pp.146-153
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• 2014

본 연구에서는 입체장애 알카놀아민 첨가제인 2-아미노-2-메틸-1-프로판올(2-amino-2-methyl-1-propanol, AMP)과 2-아미노-2-메틸-1,3-프로판디올(amino-2-methyl-1,3-propanediol, AMPD)가 $K_2CO_3$ 흡수액의 이산화탄소 흡수속도와 $KHCO_3$ 고체염의 석출에 미치는 영향에 대해 고찰하였다. 흡수온도 $40^{\circ}C$와 $60^{\circ}C$에서 wetted-wall column을 이용하여 흡수속도와 이산화탄소 평형분압을 측정한 결과, 30 wt%의 고농도 $K_2CO_3$에 대해 5 wt% AMP와 AMPD는 흡수속도를 증가시키는 동시에 평형분압을 감소시켜, 흡수촉진제로서 흡수성능을 향상시키는 것으로 확인되었다. 또한, 회분식 냉각결정화 실험 결과, 복수의 히드록실기를 포함하는 AMPD가 흡수액을 냉각시 석출되는 $KHCO_3$ 고체염의 양을 증가시키는 것으로 나타났다.