• 동력기계공학회지
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• 제16권3호
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• pp.10-15
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• 2012

Recently we have a growing interest in environmental pollution and alternative energy. Diesel engine is generally used to produce the power on the ground and the sea. However, the combustion characteristics are changed on account of the wear of fuel system and the altered ambient condition of the combustion chamber by the increment of the engine operation hour. Therefore combustion characteristics on fuel injection timing are experimentally investigated to find out the optimum fuel injection timing in the case of the aged diesel engine using biodiesel blend oil. Cylinder pressure, rate of pressure rise, rate of heat release and combustion gas temperature are risen by the advancing fuel injection timing, while the exhaust gas temperature and soot emission level are decreased by the advancing of fuel injection timing. The least specific fuel oil consumption is indicated at BTDC $26^{\circ}$ CA on the 75%load and at 1800rpm.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.331-336
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• 2002

Satellite positioning technology has been widely used in all kinds of military and civil land, marine, space and aeronautical target positioning tasks, navigation activities and accurate surveying measurements since 90s in the last century due to it advantage in providing all-weather, real-time, three dimensional and high precision positioning information, as well as speed and accurate timing information. By now, it has already formed a new hi-tech industry basically. This paper briefly reviews the development of the global satellite positioning and navigation technologies including the basic information of China′s "Plough navigation system", introduces the history of satellite positioning technology and its major application fields as well as the status quo of this being industrialized trade in China, gives an account of the writers′ vision for the application and prospect of the satellite positioning technologies in China, and approaches the tactics and stresses of the satellite positioning technology′s application and its industrialization future in China.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.49-59
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• 2008

The effects of design parameters on the pellet transport rate in the ejector system which is widely used in the production processes of automotive parts were investigated experimentally. The primary nozzle geometry, the area ratio (R) of nozzle exit cross-sectional area to mixing chamber cross-sectional area and the distance (S) from primary nozzle exit to mixing chamber entrance were considered as the design parameters. The area ratios of the primary nozzle were varied from R=0.10 to R=0.25, 0.30, 0.40 and 0.55. The primary nozzle was positioned at the non-dimensional distance (S/D) of 1.30, 1.87, 2.44, 3.00 and 3.75, normalized using the mixing chamber diameter (D). The design parameters were determined to run with high efficiency by measuring the pellets transport rate. The geometry and the area ratio (R) of the primary nozzle had an effect on the pellet transport rate of the ejector system, and the area ratio of R=0.3 was carefully selected after taking the minimum fluidization velocity and transport rate of applied pellets into account. The higher pellet transport rate with the variation of the distance (S/D) was observed at S/D of 2.44.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.197-204
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• 2005

1983년에 교통안전특정해역으로 설정되어 운영 중인 여수 ${\cdot}$ 광양항은 부산항과 더불어 동북아 중심항만(Hub Port)으로서 향후 2011년까지 총 33개의 컨테이너 선석 둥이 개발 추진 중에 있다. 또한 해상교통량이 급격히 긍가하고 있으며, 선박의 대형화, 고속화로 인하여 대형사고의 발생우려가 상존하는 지역이다. 본 연구에서는 여수 ${\cdot}$ 광양항의 미래 지향적인 안전한 해상교통환경을 조성하기 위한 체계적이고 종합적인 선박안전운항 방안을 마련하기 위해서 여수 ${\cdot}$ 광양항 입출항 항로에 대한 해상교통환경을 면밀히 분석 ${\cdot}$ 평가하여 해양사고 예방을 위한 종합적인 해상교통안전체제 구축에 필요한 문제점을 도출한다.

• 한국철도학회논문집
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• 제19권3호
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• pp.373-379
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• 2016

현재 우리가 선도하는 LTE-R 기술을 활용한 철도무선신호제어시스템 기술개발은 기존 신호시장에 미치는 파급효과가 상당할 것으로 예상되며 세계 철도신호시장의 선점을 위해 조속한 실용화사업이 절실한 시점이다. 철도무선신호제어시스템의 실용화사업에는 막대한 예산이 소요되기 때문에 그 가능성에 대해 막연한 기대를 갖고 접근하기 보다는 국내 외 시장성, 연관 산업의 파급효과 등을 고려하여 타당성 여부를 사전에 검토하여 사업추진을 면밀하게 분석해야 할 것으로 판단된다. 따라서 본 연구에서는 대상사업의 실용화가 장래 철도부문과 국가산업부문에 미치는 효과 등을 조사 및 분석하여 시장성 및 관련 산업에 미치는 영향을 기회가치성을 판단할 수 있는 경제적 타당성 분석체계의 틀을 정립하고 사례분석을 통해 검증하였다.

• Journal of Mechanical Science and Technology
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• 제15권1호
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• pp.88-97
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• 2001

The present study numerically investigates the fuel-air mixing characteristics, flame structure, and pollutant emission inside a double-swirler combustor. A PSR(Perfectly Stirred Reactor) based microstructural model is employed to account for the effects of finite rate chemistry on the flame structure and NO formation. The turbulent combustion model is extended to nonadiabatic flame condition with radiation by introducing an enthalpy variable, and the radiative heat loss is calculated by a local, geometry-independent model. The effects of turbulent fluctuation are taken into account by the joint assumed PDFs. Numerical model is based on the non-orthogonal body-fitted coordinate system and the pressure/velocity coupling is handled by PISO algorithm in context with the finite volume formulation. The present PSR-based turbulent combustion model has been applied to analyze the highly intense turbulent nonpremixed flame field in the double swirler combustor. The detailed discussions were made for the flow structure, combustion effects on flow structure, flame structure, and emission characteristics in the highly intense turbulent swirling flame of the double swirler burner.

• Journal of Multimedia Information System
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• 제9권2호
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• pp.121-126
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• 2022

The shortest path betweenness value of a node quantifies the amount of information passing through the node when all the pairs of nodes in the network exchange information in full capacity measured by the number of the shortest paths between the pairs assuming that the information travels in the shortest paths. It is calculated as the cumulative of the fractions of the number of shortest paths between the node pairs over how many of them actually pass through the node of interest. It's possible for a node to have zero or underrated betweenness value while sitting just next to the giant flow of information. These nodes may have a significant influence on the network when the normal flow of information is disrupted. We propose a betweenness centrality measure called collective betweenness that takes into account the surroundings of a node. We will compare our measure with other centrality metrics and show some applications of it.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.342-345
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• 2005

This paper describes dynamics analysis of a small training boat and a new type of ship's autopilot not only to keep her course but also to reduce her roll motion. Firstly, statistical analysis through multi-variate auto regressive model is carried out using the real data collected from the sea trial on an actual small training boat Sazanami after the navigational system of the boat was upgraded. It is shown that the roll motion is strongly influenced by the rudder motion and it is suggested that there is a possibility of reducing the roll motion by controlling the rudder order properly. Based on this observation, a new type of ship's autopilot that takes the roll motion into account is designed using the muti-variate modern control theory. Lastly, digital simulations by white noise are carried out in order to evaluate the proposed system and a typical result is demonstrated. As results of simulations, the proposed autopilot had good performance compared with the original data.

• 한국치위생학회지
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• 제6권3호
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• pp.243-261
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• 2006

Priority setting in national health insurances in major advanced countries and the nation was investigated to draw the criteria for priority setting and suggest the most rational criteria for dental insurance so as to help secure the efficiency of medicare financing and individual's health right and also elevate medical consumers' satisfaction with health insurance. 1. Priorities in national health insurance are different from country to country, depending on the medical security systems, priority introducing conditions, and social environment, but have many common factors. 2. The priority setting criteria for national health insurance in those countries include the following in common: the efficiency, equity, and cost effect of treatment, emergency of treatment, consumption of expense, efficacy of treatment, patient's receptiveness, patient's demand, severity of disease, and patient's responsibility for the disease. 3. In oral diseases, severe diseases including oral cavity cancer are low in rate, and in-hospital treatments are few. From the above findings, it is suggested that dental insurance should establish discriminative criteria for priority setting by reflecting the aspects of dental diseases and system difference between dental and other health insurances and taking account of efficiency of treatment through prevention, cost effect, prevalence and incidence of generalized diseases, and individual's financing burden.

• 한국멀티미디어학회논문지
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• 제17권8호
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• pp.946-952
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• 2014

Mobility prediction is one of hot topics using location history information. It is useful for not only user-level applications such as people finder and recommendation sharing service but also for system-level applications such as hand-off management, resource allocation, and quality of service of wireless services. Most of current prediction techniques often use a set of significant locations without taking into account possible location information changes for prediction. Markov-based, LZ-based and Prediction by Pattern Matching techniques consider interesting locations to enhance the prediction accuracy, but they do not consider interesting location changes. In our paper, we propose an algorithm which integrates the changing or emerging new location information. This approach is based on Active LeZi algorithm, but both of new location and all possible location contexts will be updated in the tree with the fixed depth. Furthermore, the tree will also be updated even when there is no new location detected but the expected route is changed. We find that our algorithm is adaptive to predict next location. We evaluate our proposed system on a part of Dartmouth dataset consisting of 1026 users. An accuracy rate of more than 84% is achieved.