• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.2
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• pp.62-69
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• 2003

Swirl injectors have the advantage of stable combustion, high efficiency, and insensibility to variable O/F ratio. Recess length is the length from outer orifice tip to inner orifice tip. It is the very important variable of performance of swirl type injector Recess length have influence on collision, mixing, spray, and combustion of propellants. This study investigated on the engine performance with the change of recess length through CFD, cold flow test, and combustion test. In result, we could confirm the change of engine performance with the change of recess length. And we found that performance forecast process through CFD, cold flow test is the right process through combustion test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1502-1508
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• 2011

One dimensional simulation model of an EFI small engine has been developed based on the commercial small engine. Newly developed simulation model has been evaluated comparing with the experimental results to check the validity. Simulation result shows very good agreement having margin of error of 3 percentage compared with experimental torque and power values. Also, to improve the small engine performance, the influence of the intake valve timing and duration on the engine performance has been analyzed using the simulation model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.37-43
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• 2020

The seismic reinforcement ratio of SOC facilities, such as domestic roads and railroads, is 96%. Out of approximately 7 million buildings as of 2016, only 0.51 million buildings with seismic performance were secured. Although the proportion of masonry structures is 38.8% of the total buildings, there is almost no seismic resistance, only 2.0%. To solve the problem in Korea, government-level seismic measures are being promoted, but the situation is insufficient. Overseas, the UBC research team in Vancouver, Canada, has developed and used EDCC to reinforce the seismic performance of masonry buildings. EDCC is a construction material that can secure concrete ductility capability by mixing fibers and secure deformation resistance of concrete through bridging action. It is necessary to examine various materials because EDCC is not used as a spray type of secure seismic reinforcement. In this study, as part of the research and development of spraying materials to improve the durability of masonry buildings, this study examined the spraying characteristics of fiber-reinforced mortar according to fiber use and the viscosity change according to the use of thickener. As a result, the working performance of the fiber-reinforced mortar for seismic reinforcement was improved when using 1% fiber and 1% thickener.

• 한국도로학회:학술대회논문집
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• 2008.10a
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• pp.103-109
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• 2008

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.1
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• pp.54-60
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• 2004

Experimental study on combustion characteristics of double swirl coaxial injectors has been conducted for the assessment of critical injector design parameters. A reusable, subscale thrust chamber has been fabricated with a water-cooled copper nozzle. Two different configurations of injectors have been tested for the understanding of the effects of recess length on high pressure combustion. Clearly, the recess length drastically affects the combustion efficiency and hydraulic characteristics of an injector. Internal mixing of propellants in an injector with recess number of two increases a combustion efficiency and reveals sound combustion although a pressure drop required for the same amount of mass flow rates increases compared with an injector of recess number of one.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1108-1114
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• 2007

The effect of oxidizer injection angle on the combustion characteristics of end-burning hybrid combustor is numerically investigated. Besides the previously studied parameter(injector arrangement, port diameter and O/F ratio), three different injection angle are considered: parallel angle to fuel surface(Case 1), +30 degree inclined angle toward the fuel(Case 2) and 30 degree inclined angle toward the nozzle(Case 3). It is found that Case 2 has the best mixing pattern in the upstream area but has the worst combustion efficiency since non negligible amount of unburned fuel is expelled from the nozzle. In contrast, though Case 1 and Case 3 showed relatively low mixing effect than the Case 2, they had high combustion efficiency. The comparison of numerical results between Case 1 and Case 3 demonstrate that no major difference is encountered, however, Case 1 is expected to have the best combustion efficiency due to the low residence time of the Case 3 injector which heads toward the nozzle.

• Journal of Energy Engineering
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• v.26 no.1
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• pp.28-33
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• 2017

A liquid nitrogen engine is a highly clean power engine, which does not emit any hazardous substances in its fumes. Additionally, it has an advantage over electric vehicles, as its energy density is larger than that of a battery. The use of an existing liquid nitrogen engine is typically limited to the reciprocation type. In this study, the concept of a nitrogen engine equipped with a scroll expander is introduced. The engine's efficiency was shown to increase when the scroll expander was utilized in the engine, while also adding to the simplification of the structure. Therefore, compared to the existing reciprocation-type engine, the engine with the scroll expander has the potential to be both technically and economically more competitive. In this study, the performance of a liquid nitrogen engine equipped with a scroll expander was analyzed while altering the injection pressure profile of liquid nitrogen.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.9-12
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• 2004

A numerical simulation is presented for investigating the effects of pressure ratio of $D_2$ injector to supersonic nozzle on the Population inversion in the DF chemical laser cavity, while a latins concurrently takes place. In this study, these phenomena are investigated by means of analyzing the distributions of the DF excited molecules, while simultaneously estimating the maximum small signal gains and power in the DF chemical laser cavity. Major results reveal that the higher $D_2$ injection pressure provides a favorable condition for $DF^{(1)}$-$DF^{(0)}$ transition to generate the higher power laser beam.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.11a
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• pp.49-55
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• 1995

이원 액체추진제를 사용하는 인공위성용 로켓 추진기관의 개발을 위한 핵심부품별 개념 및 상세설계, 성능해석, 성능실험용 시작품의 제작, 수류 성능실험 및 지상 연소시험이 수행되었다. 인공위성 궤도조종용 로켓 추진기관은 1.38MPa의 연소실 압력으로 4초동안 1780N(400$Ib_f$)의 평균추력을 내도록 설계되었으며, 산화제로는 질산, 연료로는 트리 에틸렌 아민(triethylene amine, TEA)과 자이리딘(xylidine)의 혼합물로 구성된 접촉발화형 이원 액체추진제를 사용하고, 추진제를 가압방식에 의해 연소실에 분사하는 방법으로 분사충돌, 미립화, 그리고 기화 후 연소시키게 된다. 효율적인 설계를 위하여 설계전용 소프트웨어를 개발하였으며, 추진기관의 핵심부품별로 유동 시뮬레이션을 수행하고, 해석결과와 수류 실험결과를 바탕으로 설계를 수정, 보완하였다. 지상 연소시험 및 수류 성능실험을 위하여 추진제 공급장치 및 계측 시스템이 설계, 제작되었고, 시스템의 작동 및 자료처리를 위한 소프트웨어를 개발하여 수류 성능실험 및 지상 연소시험에 사용하였으며, 연소시험결과 지상 평균추력 378$Ib_f$를 발생하였다.

• Bulletin of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.21-27
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• 1995

초고속선에 관련된 점성유동은 저한성능 향상과 운항자세 제어를 위해 사용되는 다양한 선체부 가물의 저항 예측과 초고속선에 많이 사용되는 물분사 추진장치 입구 형상의 설계 그리고 임펠 러에 이르는 덕트 유동의 예측을 중심으로 관심을 받아왔다. 본 소고에서는 통상적인 선박의 경우와는 구별되는 초고속선 고유의 점성유동 특성에 관하여 간략히 논의하기로 하고 내용을 크게 선체-부가물 점성유동과 물분사 추진장치에 관련되어 있는 덕트유동으로 나누어 기술하 였다.