• Proceedings of the Korean Information Science Society Conference
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• 2007.10c
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• pp.228-232
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• 2007

정보화 시대에 방대한 양의 정보에서 필요한 정보를 효율적으로 찾아내는 것은 그 무엇보다도 중요하다. 이를 위해 많은 검색 엔진이 효율적인 검색 결과 제공을 위해 노력하고 있지만 그 인터페이스의 문제로 인하여 사용자가 검색결과를 효율적으로 받아들이기 어려우며 또한 원하는 정보를 검색하기 위해서는 일정 수준 이상의 검색 능력을 필요로 한다. 이 논문에서는 기존의 검색 엔진의 인터페이스 변경을 통하여 시각적인 연관성 정보를 제공하며 이를 통해 사용자가 검색 능력에 구애받지 않고 정확한 답을 얻을 수 있도록 유도한다. 또한 이 과정에서 기존의 키워드 추출 알고리즘의 문제점을 발견하여 이를 단어간의 수식 관계를 이용하여 해결하였다. 또한 단어간의 수식 관계를 이용하여 효율적으로 문서간의 연관성을 생성할 수 있는 알고리즘을 제시하였다.

• Clean Technology
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• v.15 no.1
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• pp.54-59
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• 2009

In this study, the separation of water/bitumen emulsion was investigated by chemical demulsification method. Motor oils (GS Caltex Deluxe Gold V 7.5W/30, Hyundai gear oil 85W/140) and asphalt (AP-5, KS M 2201, Dongnam Petrochemical MFG. Co.) were used as model oils in the preliminary experiments to effectively remove water from water/bitumen emulsion. The bitumen extracted from Canadian oilsands was used in this study. The water/oil emulsion was not separated without demulsifiers, and Hyundai motor oil showed higher efficiency of water separation at a low concentration of demulsifier compared with that for GS Caltex motor oil. However, as the concentration increased, the efficiency did not rapidly increase compared with that of GS Caltex motor oil. It was highly speculated that the water phase of Hyundai motor oil was not dispersed well compared with that of GS Caltex motor oil because the viscosity of Hyundai motor oil was much higher than that of GS Caltex motor oil. The demulsifier of higher HLB (hydrophilic - lipophilic balance) value had high separation efficiencies in water/oil emulsion. The TWEEN 20 (polyoxyethylene sorbitan monolaurate solution) showed better separation efficiency than other demulsifiers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.516-521
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• 2012

Computational simulation has been conducted to analyze the oil separation performance of gasoline engine oil separators. Two models are compared to select a proper oil separator for the engine. To analyze oil separation characteristics, d50 and separation efficiency have been calculated for each separator. As a result, model A shows excellent d50 and separation efficiency, and model B shows good pressure-drop characteristics. Model B is recommended for the general gasoline engine with low crank-case pressure and low oil consumption. Model A is recommended for the engine with high crank-case pressure and high oil consumption, especially equipped with special exhaust gas treatment system, that is critical to the oil contamination.

• Journal of Energy Engineering
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• v.21 no.4
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• pp.411-418
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• 2012

The effect of built-in volume ratio of expander on the performance of a two-loop Rankine cycle system for engine waste heat recovery of vehicle has been investigated. In the case of positive displacement expander in the various operating condition of the vehicle, it can operate in both under-expansion and over-expansion conditions. Therefore, the analysis of off-design performance for the expander is very important. Furthermore, the volume and weight of the expander as well as the efficiency must be considered in the optimization of the expander. This study shows that the built-in volume ratio of expander causing under-expansion at a target condition is more desirable considering the off-design performance and size of the expander, based on the simple modeling of off-design operation of the expander.

• Journal of the Korean Institute of Gas
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• v.20 no.1
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• pp.52-61
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• 2016

Liquefied petroleum gas is regarded as a promising alternative fuel as it is eco-friendly, has good energy efficiency and output performance, practically and has high cost competitiveness over competing fuels. In spark-ignition engine, direct injection technology improves engine volumetric efficiency apparently and operates engine using the stratified charge that has relatively higher combustion efficiency. This study designed a combustion chamber equipped with visualization system by applying gasoline direct injection engine principle. In doing so, the study recorded and analyzed ignition probability and flame propagation process of spark-ignited direct injection LPG in a digital way. The result can contribute as a basic resource widespread for spark-ignited direct injection LPG engine design and optimization extensively.

• Journal of the Korean Institute of Gas
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• v.17 no.5
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• pp.8-14
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• 2013

Hydrogen-natural gas blends(HCNG) engine is optimizing technology of performance and emission characteristics with use of hydrogen's fast flame speed and wide flammability limit. As lean-burn limit is extended, the improvement in thermal efficiency and harmful emissions can be achieved. However, the extension of lean-burn limit under a wide open throttle operation point could be realized with the increase in boosting capacity in a lean-burn engine with turbo-charging system. In the present study, the power output characteristics of HCNG engine with turbo-charger change is assessed and feasibility of the increase in boosting capacity is evaluated. The turbo-charger design with high efficiency at higher flow rate rather than higher boosting pressure makes efficient operation possible at relatively rich mixture condition.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.684-686
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• 2014

It is difficult to effectively search and data management due to the increasing number of web is now. While Semantic Web technologies and the development of next-generation wepin this as a way to overcome them, and monopolize the domestic utilization is not overwhelming introduction to the Semantic Web technology is being used in existing search engines. This causes the development of the Semantic Web is becoming slower, and reluctant to use the Semantic Web users who use search engines as well. In this paper, compared to the currently used web and the next generation of the web, and why utilization is low compared to the search engine you are using an existing Web technology that uses the Semantic Web technology is a search engine, what research was that the inefficient because, as a RDF-based Semantic suggest how to improve the efficiency solved by designing the web.

• Journal of the Korean Society of Visualization
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• v.3 no.2
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• pp.14-20
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• 2005

내연기관 연소는 난류유동, 분무, 연소, 열전달의 복합적인 현상으로서 열역학적 해석이 주류를 이루어 왔으나 컴퓨터의 발전에 따라 효율 개선과 공해 저감을 목표로 전산유체해석 기법이 적극적으로 도입되고 있다. 내연 기관 연소의 근간을 형성하는 난류 연소 모델링의 기본 개념으로서 가솔린엔진에서의 예혼합연소와 디젤엔진에서의 확산연소에 대한 영역조건평균(zone conditional averaging) 모델과 조건평균닫힘(conditional moment closure) 모델에 대해 설명하였으며 $NO_x$와 soot 예측에 대한 적용과 엔진응용 사례를 소개하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 1998.10a
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• pp.359-364
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• 1998

지금까지 정보 검색에 대한 많은 연구가 있어 왔지만, 여전히 여러 가지 문제들로 인해 사용자는 많은 시간을 소비하게 된다. 본 논문에서는 이러한 문제를 해결하기 위해 검색결과를 분석하여 중복된 URL을 제거하고, 접근이 불가능한 URL 정보를 사용자에게 보여준다. 해결 방안으로는 멀티쓰레드를 이용한 로봇 에이젼트가 자동으로 각 URL을 방문함으로써 가능하게 했으며, 사용자는 직접 방문하지 않고도 접근 불가능한 이유를 미리 알게된다. 구현된 메타 검색 엔진을 기존의 검색 엔진들과 비교 했을 때 약 13%의 효율성 향상을 가져왔으며, 앞으로 시소러스 등을 이용한 더 많은 연구가 진행될 것이다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.580-585
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• 2003

정보화 수준을 검정하는 다양한 영역 중 실기시험은 채점 강의 문제로 많은 비용과 시간이 소요되고 있다. 본 연구에서는 컴퓨터활용능력을 검정하는 Excel 실기시험을 자동으로 채점하는 웹 기반 채점엔진을 개발하고자 한다. 출제자의 출제의도를 반영한 채점항목 및 채점기준을 유연하게 등록할 수 있게 하고, 틀리거나 감점된 문항에 대해 오답의 이유를 정확하게 제공하는 데에 개발의 초점을 맞추었다. 엑셀 자동채점 엔진을 활용하면 Excel 실기시험의 출제방향에 크게 위배되지 않으면서 사람이 채점타는 경우보다 객관성, 정확성 비용 소요시간의 면에서 기대효과를 꾀할 수 있다.