• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.12a
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• pp.665-668
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• 2003

컴퓨터 바이러스 문제에 대한 해결 주체는 현재의 클라이언트 중심에서 서버 중심으로 옮겨가는 것이 바람직하다. 그러나 지금까지 나온 서버용 안티바이러스 엔진들은 기존의 클라이언트용 엔진에 대한 반복 구현적인 성격이 강했기에 서버 시스템 자체의 특성을 충분히 감안하지 못하고 있다. 본 논문에서는 대부분의 서버들이 다수의 CPU 가진 병렬처리 시스템임을 감안하여 이러한 특징을 반영하여 전체적인 시스템 효율성을 높이도록 새로운 안티바이러스 엔진을 설계한 후 현재 구현 중인 주요 연구 내용을 소개한다. 다중프로세서 시스템에서 실행되는 안티바이러스 엔진은 하나의 모니터링 모듈에 다수의 동등한 에이전트 엔진을 가지고 구성된다. 모니터링 모듈은 엔진의 설치와 동적 부하균형, 자동갱신 등의 일을 담당한다. 에이전트 엔진들은 안티바이러스 기능을 기반으로 다양한 실행패턴을 가질 수 있으며 이를 통하여 서버에서 수행되는 효율성을 높일 수 있게 해준다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.62-67
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• 2004

This paper investigates the off-design performance of methane-fueled air turbo ramjet(ATR) engine in subsonic flight speed range. The ATR engine was modeled and simulated numerically. Each component was modeled to enable their off-design calculation. Compressor operating point was determined by flow matching with nozzle, and turbine by work matching. The ATR engine exhibited quite different off-design behavior compared to the conventional gas turbine engine.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.64-71
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• 2006

For SUAV is required to have the capacity of VTOL and fast forward flight, the SUAV development program has decided to adopt the tiltrotor mechanism which includes helicopter and turboprop mechanisms. From the engine point of view, the key engine parameters such as engine operating mechanism, engine control scheme, the dynamics characteristic of power train, engine intake/exhaust concept, and engine installation requirements should fulfill the requirements of the two different mechanisms, helicopter and turboprop. And for the maximum efficiency of the rotor, rotational speed for the two modes are 20% different, the power train shall find a way to make it so. Meeting these specific requirements for the tiltrotor mechanism, this research begins with a conventional OTS(off-the-shelf) turboshaft engine survey and minimizes engine modification to develop an economical propulsion system. The engine technical review has been performed on the basis of those requirements and capabilities.

• Transactions of the KSME C: Technology and Education
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• v.3 no.1
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• pp.15-21
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• 2015

In this paper a prediction method of GHP performance is proposed for increasing design accuracy. Two compressors with different capacity and 2311cc gas engine are used for prediction and the target capacity of GHP is 25HP. For predicting GHP performance at first the operation points are randomly selected and then as compared with compressor performance date and heat exchanger characteristic, more accurate operating points are decided through recursive calculation. Lastly engine performance date is used for calculating gas consumption volume. Predicting heating mode performance of GHP, evaporator is separated to the two section of absorbing heat in outdoor air and in engine. From the experimental results, it was found that the simulation model is good for the predicting GHP efficiency and the difference of predicted and measured efficiency is less than 5%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.144-152
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• 2011

In order to investigate the operation performance behaviors of the UAV's propulsion system to be operated long time in high altitude, the engine performance tests, which are simulated in the altitude engine test facility should be needed. If the test is performed in a existing altitude engine test facility, additional test apparatuses are required. Among them a proper design of the inlet and exhaust ducts that may directly affect the engine performance is very important. If the design is not adequate, the engine performance loss due to the flow behavior change and the pressure loss may be not similar to the real engine performance. In this work, firstly the engine inlet and exhaust ducts to be mounted to the existing altitude facility are modelled in 3D and its flow behaviors and pressure losses are analyzed using a commercial CFD tool, ANSYS's CFX, and the engine performance with the duct losses is calculated using the performance analysis program developed by C. Kong et al. Finally, the optimized inlet and exhaust ducts' configurations are proposed through the repeated analyses of various duct configurations.

• Journal of the Korean Society for information Management
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• v.17 no.2
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• pp.85-100
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• 2000

Meta search engines have been used as the first engine because they let users several search engines at once for their queries and give them the search results. The purpose of this study is to examine the features and functions of 17 meta search engines in order that it helps users select and execute effective searches on meta search engines. Each selected engine is analyzed based on the criteria evaluating both meta search engines and general search engines. The results show that each meta search engine has its own characteristics while there are common features among them. It is expected that the results of this study will help users utilize meta search engines and provide meta search engine designer basic ideas.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.130-133
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• 2009

The sequence of the propellant supply is very important for the reliable and safe operation of a LRE combustion test. So combustion performance tests were performed to find an optimum test sequence by changing supply time of propellants and purge gas in the moment of ignition and extinction. The liquid rocket engine consisted of a catalytic ignitor and six swirl-coaxial injectors which used hydrogen peroxide and kerosene. Conclusively, an optimum sequence was found for stable combustion in the moment of ignition and extinction.

• Journal of the korean Society of Automotive Engineers
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• v.8 no.2
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• pp.13-21
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• 1986

점차 엄격해지는 요구조건을 만족시켜 주기 위해서는 승용차용 엔진의 실제특성과 운전특성을 지 배하는 설계변수의 조절은 불가피하며, 그중에서도 엔진의 핵심부인 연소질의 설계는 가장 중요 하다. 부분 부하에서의 SI기관의 연료경제성을 향상시키는 가장 좋은 방법이 압축비를 상승시 키는 것이므로, 앞으로의 여소실은 고압축비에서도 옥탄가가 높은 연료를 요구하는 성향을 낮 추는 특성을 갖고 있어야 한다. 새로운 엔진의 향상을 최적화하기 위하여는 quench area의 크 기와 위치 그리고 적절한 quench distance의 성질이 중요하며, 또한 연소실의 소형화, 스파크 플러크의 위치, 표면적/체적의 비 그리고 화염전파거리등도 고려에 넣어야 한다. 승용차용 엔진의 요구조건은 연소실을 피스톤 크라운에 위치시키는 용이한 방법을 통하여 해결될 수 있으며, 이 러한 형상의 연소실은 실린더 헤드에 장치한 연소실과 비교하여 다음과 같은 장점을 갖고 있다. - 스파크 플러그 주변에 연소실을 배치하기 쉽다. - 연소실 내에 quench area의 설정이 자유롭다. - 연소실 layout의 개조없이 압축비의 설정이 자유롭다. - 연소실의 조합이 간단하다. - 실린더벽으로의 열손실이 감소되어 열효율이 증대된다. - 공연비의 희박가능한계가 크다. - EGR성능이 향상되어 NOx 의 배출과 연료소비율이 감소된다. - 필요하다면 연소실실 또는 직접분사식 Diesel 기관으로서의 개조가 간단하다. 만약 생산단가가 크게 상승하지 않는다면, NOx의 배출과 연료소비율이 작으면서도, 비출력이 큰 4-밸브 연소실이 실용화 될 전망이다.

• Journal of Broadcast Engineering
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• v.10 no.2
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• pp.202-209
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• 2005

In this paper, we propose a design of the metadata engine of the video recording system to minimize the retrieval time. For this purpose, the proposed metadata engine stores the XML metadata as a separated fragment and construct a hierarchical indexing scheme based on the contextual and structural properties of metadata. The hierarchical indexing scheme is consisted of a node index for basic searching and a group index for advanced searching. In this way our approach can minimize the number of indexes and thus the retrieval time. Our simulation results show that the response time of our proposed system is shorter than that of the previous works.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.277-284
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• 2017

This study is the results of the analytical research for a dual-model scramjet engine flowpath which is included inlet, isolator, combustor, and nozzle. To design a dual-mode scramjet engine and to investigate its performance, the performance analysis models and tools are required to develope for aerodynamic, thermodynamic characteristics, propulsion, and total system. Therefore, analysis models for air inlet, isolator, supersonic combustor, and nozzle of a dual-mode scramjet engine were accomplished, the performance characteristics of a dual-mode scramjet engine is investigated with using the developed analysis tools.