• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.3
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• pp.208-212
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• 2015

This study will design the structural optimization of 21 W LED heat sink using the thermal conductive plastic materials. The thermal conductive plastic heat sink is inferior to aluminum heat sinks in thermal properties. This study will solve this problem using formability of thermal conductive plastic heat sink. A heat sink was optimized in terms of the number, and the thickness of fins and the base thickness of the heat sink, using the Heatsinkdesigner software. Also by using SolidWorks Flow simulation and thermal analysis software, the thermal characteristics of the heat sink were analyzed. As the result, the optimized heat sink has 17 fins, which are 1.5 mm thick and a 3.7 mm-thick base. The highest and the lowest temperature were $51.65^{\circ}C$ and $46.24^{\circ}C$ respectively. Based on these results, The thermal conductive plastic heat sink is considered possible to overcome heating problem when designing in complex structure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.233-239
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• 2003

The present study has numerically investigated the combustion processes in the solid propellant rocket engine. The two step global reaction model for condensed phase and five step global reaction mechanism for gas phase are adopted to predict the detailed flame structure near double-base solid propellant surface. The turbulence-chemistry interaction is represented by the PaSR(Partially Stirred Reactor) model. To reduce the uncertainties for convective heat transfer near solid fuel surface having strong blowing effect, the Low Reynolds number k-$\varepsilon$ turbulent model is employed. Based on numerical results, the detailed discussion has been made for the turbulent combustion processes and transient behavior of pressure and temperature fields in the solid propellant rocket engine.

• International Journal of Automotive Technology
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• v.3 no.1
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• pp.41-46
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• 2002

Effect of secondary air injection (SAI) on hydrocarbon reduction has been investigated in a single cylinder Sl engine operating at cold-steady/cold-start conditions. The hydrocarbon emission and exhaust gas temperature with and without catalytic converter were compared with continuous and synchronized SAIs, which injected secondary air intermittently into exhaust port. Effects of SAI location, SAI pressure, SAI timing, and location of catalytic converter have been investigated and the results are compared for both SAls with base condition. At cold-steady condition, the rate of HC reduction increased as the location of SAI was closer to the exhaust valve for both synchronized and continuous SAls. The emission of HC decreased with increasing exhaust-A/F when it was rich, and was relatively insensitive when it was lean. The timing of SAI in synchronized SAI had significant effect on HC reduction and exhaust gas temperature and the synchronized SAI was found to be more effective in HC reduction and exhaust gas temperature compared to the continuous SAI . At cold-start condition, when the catalytic converter was located 20 cm downstream from the exhaust port exit, the catalytic converter warm-up period for both SAls decreased by about 50%, and the accumulated hydrocarbon emission during the first 120 s decreased about by 56% and 22% with the synchronized and continuous SAIs, respectively, compared to that of the base condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.81-89
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• 2014

This study researched on the effect of HP/LP-EGR system to improve fuel consumption of Low Temperature Combustion Engine. Firstly, low temperature combustion engine with HP/LP-EGR system was established using 6.0L wastegate turbocharger HDDI engine. And suppliable EGR rate of the engine was proven to be enough to realize stable low temperature combustion. Then, optimum operating strategy was founded to develop fuel consumption of the engine. Control parameters were HP/LP-EGR valve and IPCV(Intake Pressure Control Valve) duty. Experiments method was that characteristics of the engine were measured and analyzed according to HP/LP-EGR strategies while EGR rate was fixed. Operating range for the strategy were divided into three parts, low load for low temperature combustion, high load for conventional diesel combustion, and transient condition. Finally, with the above strategy of this study, BSFC of the engine was improved about 2% compared to the base engine, and emission level, NOx and PM, met Tier4Final emission regulation.

• Journal of Hydrogen and New Energy
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• v.31 no.3
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• pp.307-313
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• 2020

The 3.9 liter diesel engine with a mechanical fuel injection system was converted to di-methyl ether (DME) engine and performance optimized. In order to switch to the DME engine, the plunger of the high pressure fuel pump was replaced and the diameter of the injector nozzle was increased. Through this, the disadvantage of DME having low calorific value per volume can be compensated. To optimize the performance, the number of injector nozzle holes, injector opening pressure, and fuel injection timing were changed. As a result, the optimum number of injector nozzle holes was 5, the injector opening pressure was from 15 MPa to 18 MPa, and the injection timing was 15 crank angle degree before top dead center (CAD BTDC). The power was at the same level as the base diesel engine and nitrogen oxides (NOx) emissions could be reduced.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.2
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• pp.253-259
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• 2006

There is few study which automatically diagnoses the fault from ship's monitored data. The bigger control and monitoring system is. the more important fault diagnosis and maintenance is to reduce damage caused by system fault. This paper proposes fault diagnosis system using a correlation analysis algorithm which is able to diagnose and forecast the fault from monitored data and is composed of fault detection knowledge base and fault diagnosis knowledge base. For all kinds of ship's engine room monitored data are classified with combustion subsystem, heat exchange subsystem and electric motor and pump subsystem, To verify capability of fault detection, diagnosis and prediction, FMS(Fault Management System) is developed by C++. Simulation by FMS is carried out with population data set made by the log book data of 2 months duration from a large full container ship of H shipping company.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.251-256
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• 2005

There is few study which automatically diagnose the fault from ship's monitored signal. The bigger control and monitoring system is, the more important fault diagnosis and maintenance is to reduce damage brought forth by system fault. This paper proposes fault diagnosis system using a correlation analysis algorithm which is able to diagnose and forecast the fault and is composed to fault detection knowledge base and fault diagnosis knowledge base. For this all kinds of ship's engine room monitored data are classified with combustion subsystem, heat exchange subsystem and electric motor and pump subsystem by analyzing ship's operation data. To verifying capability of fault detection, diagnosis and prediction, Fault Management System(FMS) is developed by C++. Simulation experiment by FMS is carried out with population data set made by log book data of 2 months duration from a large full container ship of H shipping company.

• ETRI Journal
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• v.41 no.4
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• pp.515-527
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• 2019

This paper discusses the design, implementation, and potential use of an ontology-based mobile pediatric consultation and monitoring system, which is a smart healthcare expert system for pediatric patients. The proposed system provides remote consultation and monitoring of pediatric patients during their illness at places distant from medical service areas. The system not only shares instant medical data with a pediatrician but also examines the data as a smart medical assistant to detect any emergency situation. In addition, it uses an inference engine to infer instant suggestions for performing certain initial medical treatment steps when necessary. The applied methodologies and main technical contributions have three aspects: (a) pediatric consultation and monitoring ontology, (b) semantic Web rule knowledge base, and (c) inference engine. Two case studies with real pediatric patients are provided and discussed. The reported results of the applied case studies are promising, and they demonstrate the applicability, effectiveness, and efficiency of the proposed approach.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.10
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• pp.112-122
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• 1996

In order to monitior machine tool condition and diagnose alarm states due to electrical and mechanical faults, and expert system using diagnostic parameters of NC machine tools was developed. A model-based knowledge base was constructed via searching and comparing procedures of diagnostic parameters and state parameters of the machine tool. Diagnostic monitoring results generate through a successive type inference engine were graphically displayed on the screen of the console. The validity and reliability of the expert system was rcrified on a vertical machining center equipped with FANUC OMC through a series of experiments.

• Journal of Biosystems Engineering
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• v.26 no.2
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• pp.141-146
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• 2001

Lots of the agricultural information come from human experiences and are in non-numerical forms. Therefore, it is difficult to process to be processed in a conventional data processing way. An internet expert system for agricultural application using the ASP(active server page) was developed to solve this problem and consisted of databases, an inference engine, and an user interface. The databases were composed of rule base, question base and link data. The inference engine was developed with the ASP for connection with web between databases. The used interface was developed with the CGI(common gateway interface), so that question could be answered on a web browser, and the session technique was used to provide proper result to each of multi-users. A prototype internet expert system was developed for diagnosis of diseases and nutritional disorders of paddy rice. The expert system was interactively worked through WWW(world wide web) at remote sites by multi-users, even at the same time. The rule base could be easily updated and modified from a web server computer by a knowledge engineer.