• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.750-755
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• 2011

The ignition characteristics of liquid rocket engine thrust chambers which have been developed by domestic technology were analyzed. Analysis results showed that low frequency fluctuation appeared in a partial ignition range according to different temperature profiles and vaporous state in the oxidizer manifold with startup sequences. This low frequency fluctuation wasn't developed as a malfunction factor, but this fluctuation is thought to be taken a continuous concern considering interfaces with engine system and launch vehicle.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.14-20
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• 2007

In this study, characteristics of jet type flame holder for ramjet engine combustors are investigated Jet flame holder can be easily controlled by the injection angle change and jet momentum variation without any thermal protection devices. Due to the intensive turbulent mixing effect, jet flame holder shows better flame holding performance than mechanical flame holders such as cavity, step and v-shape flame holder.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.323-326
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• 2014

본 논문에서는 Unity 3D 엔진을 심층 분석하여 게임개발 교육현장에서의 유용성을 검토하였다. Unity 엔진을 이용하면 필드의 제작, 캐릭터 애니메이션 세팅, 스크립트 작성, Asset 관리, 레벨 디자인 등 많은 작업을 하나의 통합 환경에서 수행할 수 있다. 또한 컴파일 과정을 거치지 않아도 게임을 제작하는 도중 언제라도 실행해 볼 수 있기 때문에 개발에 걸리는 시간을 단축 할 수 있다. 본 연구의 초점은 게임 앱 설계 관련 프로젝트의 수행이나 교육용 게임 개발의 학습 모형을 제시하기 위한 과정이다.

• Journal of the Korean Society for Library and Information Science
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• v.38 no.4
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• pp.179-192
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• 2004

In this paper, we present that the result of document clustering can change dramatically with respect to the different ways of indexing compound nouns. First of all, the automatic indexing engine specialized for Korean words analysis, which also serves as the backbone engine for automatic document clustering system, is introduced. Then, the details of hierarchical agglomerative clustering(HAC) method, one of the widely used clustering methodologies in these days, was illustrated. As the result of observing the experiments, carried out in the final part of this paper, it comes to the conclusion that the various modes of indexing compound nouns have an effect on the outcome of HAC.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.85-92
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• 2020

Ground hot-firing tests were conducted to analyze the combustion performance according to the characteristic lengths 1.37 m, 1.71 m, and 2.06 m of the combustion chamber in 200 N-class GCH4-LOx small rocket engine. Thrust, specific impulse, and characteristic velocity at the steady-state could be obtained as the key performance parameters of the rocket engine. The performance characteristics acquired through the test were compared and analyzed with the theoretical performance calculated from CEA analysis. Observation of the influence of characteristic length on the combustion performance indicates that an optimal characteristic length shall remain between 1.71 m and 2.06 m.

• Journal of Power System Engineering
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• v.15 no.1
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• pp.11-17
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• 2011

본 연구는 라디칼 착화(Radical Ignition이하 RI) 기술을 적용한 부실직분식 CNG(Compressed Natural Gas) 엔진의 구동특성에 관한 것이다. 실험엔진은 단기통 디젤엔진을 개조하여 사용하였으며, 이는 부실식 디젤엔진처럼 연소실이 주실과 부실로 나누어져 있다. 부실에 분사된 CNG는 스파크플러그로 점화하며, 부실로 부터의 연소가스가 주실 희박 혼합기를 시켜 구동하는 엔진이다. RI 기술은 연소속도를 향상시킬 수 있다. 본 연구는 주로 저부하 RI-CNG 엔진의 성능을 연구하였다. 연료분사기간은 9 ms, 공기과잉률은 1.0, 1.2, 1.4로 하였다. 연료분사시기는 엔진의 배가밸브가 닫히는 ATDC $20^{\circ}CA$ 부터 $120^{\circ}CA$ 사이로, $20^{\circ}CA$ 간격으로 지각시켜 가며 실험하였다. 본 연구는 연료분사시기 및 공기과잉률이 연소최고압력 ($P_{max}$), 연소최고압력시기(${\Theta}_{pmax}$), 도시평균유효압력(IMEP), 사이클 변동계수($COV_{imep}$), 연소속도에 미치는 양향 등을 구하고 분석하였다.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.182-194
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• 2012

To develop a liquid rocket engine with high reliability and safety under constraints of limited time and budget an optimal diagnosis system for the engine needs to be developed in parallel with the development of the engine. This paper is intended to set a development direction of the diagnosis system for the liquid rocket engine through the literature survey and addresses possible engine defects, characteristics of parameters for diagnosis and diagnostic methods including real-time diagnosis, post-test/post-flight diagnosis, fault detection method, parameter circuit method and test diagnosis. In addition tasks to be performed in the design and operation phases of the engine and foreign application case of engine diagnosis are presented.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.722-726
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• 2010

The recent deployment of RIA (Rich Internet Application) is often involved with the complex JavaScript code, which leads to the announcement of high performance JavaScript engines for its efficient execution. And the Sunspider benchmark is being widely used for the performance evaluation of these JavaScript engines. In this paper, we compare the execution methods of three high-performance JavaScript engines, Mozilla TraceMonkey, Google V8, and Apple SquirrelFish Extreme, and measure their performances using the SunSpider benchmark. We also evaluate the pros and cons of each engine, based on its execution method and the code characteristics of the SunSpider benchmarks.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.386-388
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• 2023

본 논문은 고성능 스토리지를 사용하는 환경에서 대규모 그래프를 분석을 위한 GPU 기반 그래프 분석 엔진의 I/O 최적화 전략을 제안한다. 사전 실험을 통해 최신 GPU 기반 그래프 엔진인 RealGraph^GPU 가 고성능 스토리지의 대역폭을 충분히 활용하지 못하고 있음을 발견하였다. 이를 개선하기 위해 (1) User-space I/O, (2) Asynchronous I/O 두 가지 최적화 전략을 적용하였으며, 실험을 통해 두 전략이 RealGraphGPU 의 그래프 분석 성능 향상시키는 데 효과적임을 확인하였다.

• Digital Contents
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• no.1 s.68
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• pp.64-74
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• 1999

올해 들어 월드 와이드 웹은 "증대한" 온라인 정보에 대한 주요 공급자로 자리매김했다. 웹 검색 엔진의 성능은 영구적인 시장 점유율을 확보하기 위해 고안된 새로운 서비스, 인터페이스, 기술들을 제공할 수 있도록 하루가 다르게 개선되는 것 같다.