• Tribology and Lubricants
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• v.30 no.1
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• pp.21-28
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• 2014

Damage to the cylinder liner of large ship engines, such as scuffing on the surface, can occur very easily because it is operated in a corrosive environment. This scuffing may be due to oil film destruction and corrosive wear caused by water and sulfur included in the fuel, abrasive impurities, and poor lubricants. Thus, a method for monitoring the condition and diagnosing the failure of the cylinder liner and piston ring is needed. In this study, a reciprocating friction and wear test was carried out with a cast iron specimen, which simulated an engine cylinder in a corrosive atmosphere. The lubricants used were base oil, stirred oil with distilled water, a NaCl solution, and dilute sulfuric acid. The friction coefficient and frequency spectrum were measured using a load cell and acceleration sense in each experimental condition. We then used these results to diagnose the failure of the cylinder liner.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.145-148
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• 2009

Combustion tests of a fuel-rich gas generator had been conducted using the assembly of a powerpack. A gas generator is prone to longitudinal modes of combustion instabilities in a powerpack due to the increase of a characteristic length. It has been observed that the orifice inserted at the exit of the gas generator suppresses a longitudinal combustion instability. The intensities of pressure fluctuations in the manifolds and the chamber increase quadratically with a chamber pressure. Pressure fluctuations in the fuel manifold reveal two-fold strength greater than those in the oxygen manifold and the chamber. Frequency analysis indicates nonlinear characteristics inherent in the pressure fluctuations in the fuel manifold.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.01a
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• pp.71-72
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• 2017

최근 소형 IoT 디바이스의 보급에 따라 모든 것이 인터넷과 연결되는 초연결 사회로 발전하면서 IoT 플랫폼 및 서비스 시장규모가 급격히 확대되고 있다. 특히, 스마트 홈을 위한 IoT 플랫폼에 대한 연구와 개발이 집중되고 있는데, 본 논문에서는 이러한 스마트 홈에서 다양한 IoT 기기의 시너지 효과를 극대화 할 수 있는 상황 인식 추론 시스템 서버의 성능을 분석한다. 본 논문의 IoT 기반 상황 인식 추론 시스템은 상황 정보를 RDF Triple 구조로 표기하며, 서버의 경량화 추론 엔진을 이용하여 사용자가 입력한 룰을 기반으로 주변 상황을 추론하고 사용자 맞춤형 서비스를 제공한다. 이러한 상황 인식 추론 시스템 서버의 성능을 확인하기 위해, 본 논문에서는 기존 PC 기반 상황 인식 추론 시스템 서버와 IoT 노드 기반 시스템 서버에 대한 메모리 사용량, 메모리 할당량, CPU 사용량을 비교한다.

• Journal of the Korea Society for Simulation
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• v.16 no.2
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• pp.75-81
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• 2007

Previous queue inference has been studied with some limits. Larson's inference engine, which is the basis for this paper, also processed with basic assumption that arrival process is poisson process. Our inference method, which relaxes the poisson process assumption, must be a useful tool for looking into unobservable inside of queueing systems, as well as calculating accurate system performance. This paper employs these inference methods and proves the validity. Then we apply this method to system analysis for more complicated models. At first, we suggest methods to system with known number of servers, then expand to unknown number of servers. For validating our inference approach, we run some simulation models and compare true values with our results.

• Journal of Internet Computing and Services
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• v.15 no.1
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• pp.135-142
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• 2014

In this paper, we present integrated SNS Gateway as way to reduce mobile SNS traffic. Integrated SNS gateway's role is communication broker that located between mobile clients and SNS server. In Integrated SNS gateway, web service adapter communicates with SNS Server. Experiment was performed in aspects of contents RTT and network traffic. We evaluate and propose performances of integrated SNS gateway using gateway.

• Journal of Korea Spatial Information System Society
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• v.2 no.2 s.4
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• pp.85-88
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• 2000

GPS/GIS Related Information Technology evolves drastically and a great quantity of spatial information is available to users who require highly qualitative spatial information services. Hence the development of GIS tools that can improve position accuracy and maintenance efficiency is required. To meet various requirements from users. we developed a GPS data processing component based on OLE/COM by utilizing GDK which is a unique domestic GIS product. Also we developed an application package that includes the GPS data processing component to implement GPS into GIS. The development of GPS data processing component will contribute toward the expansion of component-wise GIS softwares.

• Journal of ILASS-Korea
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• v.20 no.4
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• pp.247-253
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• 2015

Recently, the engine calibration technique has been much more complicated than that of the past engine case in order to satisfy the strict emission regulations. The current calibration method for the diesel engine which has an increasing market is both costly and time-consuming. New engine calibration method is required to develop for high-quality diesel engines with low cost and release it at the appropriate time. This study provides the optimal calibrating technique for complex engine systems using statistical modeling and numerical optimization. Firstly, it design a test plan based on Design of Experiments, a V-optimality methodology which is suitable looking for set-points, and determine the shape of test engine response. Secondly, it uses functions to make linear regression model for data analysis and optimization to fit the models of engines behavior. Finally, it generates the optimal calibrations obtained directly from empirical engine models using Grey Relational Analysis and compares the calibrations with data. This method can develop a process for systematically identifying the optimal balance of engine emissions.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.10 no.1
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• pp.243-268
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• 1999

The purpose of this study is to develop the classification scheme in subject-based directory search engine for educational research information on the web. Five classification systems. Yahoo Korea, Argus Clearinghouse, DDC, ERIC thesaurus and KEDI thesaurus were measured in terms of coverage of subject fields, system logic, accuracy of terminology and efficiency of searching. For the design of Classification Scheme, this study considered the content of subject areas, features of information resources and efficiency based on users. Finally, the Classification Scheme was established in terms of 16 main divisions and 47 sub-divisions in educational research information.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3079-3084
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• 2008

A fast response $CO_2$ analyzer has been developed for measuring the $CO_2$ concentration during transient condition of SI engine. The analyzer is based on the non-dispersive infrared absorption technique, electrical chopping system and water cooling system. The analyzer has good repeatability, linearity and permissible drift characteristic. Besides, it has 18ms with a response to measure the $CO_2$ concentration. The fast response $CO_2$ analyzer was applied to single cylinder SI engine and the $CO_2$ emission was examined during engine start. Simultaneously, the standard exhaust gas analyzer, which has slow response time, was used for considering the engine-out $CO_2$ characteristic. The developed analyzer showed much faster responsive characteristic than that of a standard analyzer and made cycle by cycle exhaust gas analysis possible. The transient engine operating characteristics will be estimated and the transient behaviors on engine-out emission and performance will be improved.

• Journal of the Korea Society for Simulation
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• v.21 no.1
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• pp.1-8
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• 2012

In recent days, global shipbuilding companies have been showing great interest in eco-friendly ship products and trying to reduce environmental pollution - harmful gas and dust in shipbuilding process. Following this trend, Life Cycle Assessment (LCA) was carried out to an application of shipyards layout. LCA is a technique used to assess environmental impacts during the life cycle of products and systems. Until now, LCA has been used through ISO 14040 in somewhat limited industries, such as Building Life Cycle Assessment. Thus, this study analyzes the shipyard layout planning framework and builds life cycle inventory along with the simulation model structure to evaluate environmental impacts.