• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.28-44
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• 2020

In this paper, the scavenging process of various transfer ports was evaluated to improve the performance of a small two-stroke engine for unmanned aerial vehicles. Three-dimensional computational fluid dynamics simulations were performed to four transfer ports for the evaluation, and a three-phase scavenging model was developed and applied to the simulation results for the quantitative comparison of scavenging performance. the short-circuit of fresh charge was restrained and an in-cylinder turbulent kinetic energy was enhanced by changing the transfer port. Also, a difference in the scavenging for each port were confirmed by applying the three-phase model to the simulation results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.12-12
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• 1997

여러 가지 형태의 연소 불안정성 중에서 50-500Hz 사이에서 발생되며 길이방향 모드(longitudinal mode)로 특징이 있는 저주파수 불안정성이 램제트 혹은 재연소기(Afterburner)의 연소 불안정성에서 가장 중요한 것이라고 여겨진다. 본 논문에서는 램제트 흑은 재연소기에서 일어날 수 있는 길이 방향의 연소 불안정성을 Modal 해석법을 사용하여 수학적인 모델로 만들었다. 특히 이 모델의 선형형태는 어떤 형태든지 선형 속도에 민감한 Burning rate 모델을 사용할 수가 있어서 보다 포괄적인 형태로 만들어져 있으며, 이 모델을 이용하여 여러 가지 연소 형상과 불완전 연소 응답 등을 연구할 수 있다. 본 논문에서는 실제 연소 형상과 유사한 삼각형 모양의 연소 형상을 사용하여 기존의 다른 모델들과 비교 분석하였다.

• Proceedings of the CALSEC Conference
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• 2003.09a
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• pp.300-306
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• 2003

① 대표적인 소기업 업종인 미용업은 기업형 미용실을 중심으로 IT기술을 활용하여 경영의 효율성, 고객서비스의 다각화, 고부가가치의 창출을 도모하고 있음. ② 미용업 시장의 변화와 함께 IT기업도 패키지 소프트웨어 서비스, ASP(Application Service Provider)서비스, 웹서비스 등의 다양한 형태를 통해 이러한 시장의 요구에 대응 ③ 저렴하고, 전문적이며, 고객요구에 대한 발빠른 대응의 가능한 미용업 특화 ASP 사업모델은 가장 경쟁력 있는 사업모델 ④ 미용실 종합관리 프로그램을 ASP형태로 제공하는 헤어짱은 '규모의 경제'에 도달함으로써 ASP사업모델의 약점인 '고정비용에 대한 대규모의 투자' '수익회수기간의 장기화'를 극복한 대표적인 소기업 ASP 서비스 브랜드(중략)

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.63-69
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• 2014

The oxidizer-rich preburner's combustion tests were fulfilled in the development process of staged combustion cycle rocket engines. The exhaust plume from an oxidizer-rich preburner is relatively transparent because combustion takes place in oxidizer rich state. During hot fire tests a still and infrared images were captured to visualize the plume structure, temperature distribution and so on. In addition, the exhaust plume was numerically investigated to figure out the detailed characteristics. The combustion was not considered for the numerical modeling, but the mixing of exhaust plume with circumstantial air was modeled by species transport model with several turbulence models. The inner structure of plume was configured out by the comparison of numerical results with experimental results, and the validity of applied numerical models was verified.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.11a
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• pp.68-81
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• 2000

Many studies for improving a scavenging efficiency have been executed by using simulative manner. This paper addresses to a scavenging process in a uniflow two stroke cycle engine. The Processes are simulated for scavenging pressure variation, after the assessment of turbulent models. The results have shown that employing RNG k-$\varepsilon$ model gave more accurate velocity profiles near the cylinder wall compared with the standard k-$\varepsilon$ model and the charged fresh air has increased with the scavenging pressure increase.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.67-75
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• 2013

The numerical analysis for the verification of preburner's cooling characteristics applying to kerosene-LOx rocket engine has been fulfilled. The distribution of combustion gas properties in primary combustion zone was calculated by the mixture ratio based on head injector arrangement, the properties of oxygen flowing in wall channels as coolant were applied under real-gas conditions, and multi-phase mixing model was employed to calculate the mixing process of primary combustion zone with liquid oxygen which was used for wall cooling. The results of numerical analysis were compared with the experimental results, hence thermo-physical properties in cooling channels and a combustor could be quantitatively identified.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.533-536
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• 2010

It has been manufactured the a prototype of the oxygen rich preburner which can be used for a small high performance liquid rocket engine. Based on the model designed and analyzed by KARI a series of the work was made. First, the layout was drawn and then two kinds of the test specimen were devised and manufactured for the hydraulic and pressure test respectively. It was confirmed that the details in designing and manufacturing the preburners. All of them efforts may help establish the bases to develop high performance liquid rocket engine.

• Information Systems Review
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• v.8 no.3
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• pp.175-200
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• 2006

Application service provider(ASP) model is emerging as a new form of application outsourcing. ASP model may be attractive for small companies and even some medium-sized companies because these companies lack appropriate resources and technical expertise to develop and operate their information system. However, studies of ASP model have so far been neglected. Service quality is argued to be a crucial success factor for ASP, but yet there is not an empirically validated instrument for measuring ASP service quality. Therefore, this paper aims to develop and test a model for measuring ASP service quality. In order to accomplish these, SERVQUAL that has developed in marketing area were adapted to the context of this study. The research sample was designed by randomly selecting 300 different companies from the database that listed up the small companies participating in "ASP based e-business project for small enterprises". 240 usable responses were received by interview. The results are that reliability and tangibility impact user performances and satisfaction more than any of the service quality dimensions.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.6
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• pp.10-20
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• 2022

The present study developed a design code for preburner of staged combustion cycle engines, which calculates preburnt gas at high-pressure oxidizer-rich conditions and predicts conjugate heat transfer and hydraulics of cryogenic fluid flow through cooling passages. It has been written based on the open-source library Cantera, into which this study has incorporated new source codes to predict correctly non-ideal thermodynamics and transport anomalies of the cryogenic fluid. For a preburner of 100 tonf-class booster engine currently under preliminary design, the present code demonstrated predictive capability and usability as a design code by comparing with CFD simulation.

• Proceedings of the CALSEC Conference
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• 2003.09a
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• pp.294-299
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• 2003

ㆍ 목적 최근 정보화 패러다임의 변화에 따라 그 영역과 도입이 확산되어가고 있는 ASP(application service provider, 이하 ASP) 형태의 정보기술 서비스 도입을 중심으로 정보기술서비스의 도입에 영향을 미치는 관련 요인들을 도출하고, 기존의 기술수용모델에 있어서의 수용요인, 특히 정보기술서비스의 특성을 고려한 새로운 모델을 제시하고 기존 이론의 검증과 보완을 시도(중략)