• The Journal of the Acoustical Society of Korea
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• v.33 no.3
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• pp.163-173
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• 2014

Sound propagation algorithm for a sonar simulator is required to run in real-time and should be able to model the range and depth dependence of the Korean ocean environments. Ray model satisfies these requirements and we developed an algorithm for range-dependent ocean environments. In this algorithm, we considered depth-dependence of sound speed through rays based on a rectangular cell method and layer method. Range-dependence of sound speed was implemented based on a split-step method in the range direction. Eigen-ray is calculated through an interpolation of ray bundles and Gaussian interpolation function was used. The received time signal of sonar was simulated by Fourier transform of eigen-ray solution in the frequency domain. Finally, for the verification of proposed algorithm, we compared the results of transmission loss with other validated models such as BELLHOP, SNUPE, KRAKEN and OASES, for the Pekeris waveguide, wedge, and deep ocean environments. As a result, we obtained satisfactory agreements among them.

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.35-41
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• 2015

Recoil system for 40mm automatic gun is a device developed to absorb the shock of explosion. It is impossible to conduct pinpoint strike due to recoil if very high explosive shock, which is generated when an automatic gun fires shells, can't be absorbed. This study covers development and verification of analysis model for recoil system by utilizing a multi-domain software. The research process is as in the following. First, an analysis model is developed to verify damping characteristics through understanding of design intention. Second, environment which is identical to a field test is set up on analysis tool after putting explosive force that is measured through the test into the analysis model. Finally, the analysis model for recoil system using the multi-domain software is verified if it has effectiveness with a comparison between internal pressure of the recoil system along with displacement of gun barrel and the field test result.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.178-180
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• 2016

TMDE(Test Measurement and Diagnostic Equipment) which is using in the military weapon system should perform the periodic calibration to maintain a measurement reliability during the life cycle, organizations are faced with increasing pressures to minimize costs while improving the reliability of test equipment. Previous studies suggest that reliability models are determined by considering simple size and characteristics of equipment, however an applying single Model may not be fit well maintenance data of many kinds of TMDEs. This paper presents that recommending an optimal calibration interval through the goodness of fit test with verifying statistical significance level among the several intervals which are computed with using major reliability models. According to the result of applying the actual proposed of calibration interval analysis method for various types of equipment, reliabilities are maintained for the end of calibration intervals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.244-251
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• 2016

In this study, the relationship between flow characteristics and projection distance, depending on the shape was examined. A numerical investigation technique for fluid analysis of a foam monitor was developed for the prediction, comparison and validation of the actual injection performance. The foam monitor changes the flow pattern of fluid flow according to the shape, The fluid losses were calculated from the numerical investigation affecting the projection distance. The basic form of foam monitor was used as a designed shape in N. The modified model used the length increase model of the flow path, and straight line of the model. The inlet pressure was 6.5bar. The results showed that the length increase model of the flow path and straight line of the model in the nozzle projection distance had improved. The results comparing the error rates projection performance were well matched to the 7.43% obtained from the validity test of the analysis method.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.377-380
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• 2006

본 논문에서는 통신해양기상위성의 지상국에 구축된 고 출력증폭기에 대한 특성 모델링 및 이에 따른 입력신호에 따른 출력 신호의 상호 간섭에 대한 결과가 정리되어 있다. 고 출력증폭기는 지상국에서 위성으로 신호를 전송할 때 필요한 장비로써 비선형 특성으로 인해 입력된 신호에 대한 다양한 하모닉 성분이 발생된다. 특히 통신해양 기상위성의 지상국의 경우에는 하나의 고 출력증폭기에 대해 두개의 서로 다른 주파수의 신호를 입력해야 하는 것을 고려해야 하기 때문에 이에 대한 영향은 사전에 반드시 분석되어야 한다. 본 논문에서는 고출력증폭기의 P1dB 특성곡선에 의해 특성 모델링을 수행한 결과 및 이러한 모델을 검증하기 위해 이미 정의된 두 신호에 대한 간섭의 양을 확인하였다. 특히 고 출력 증폭기의 전단에 속하는 상향 주파수 변환기의 특성을 고려한 신호를 사용하여 실제의 통신해양기상위성으로 데이터를 전송할 때의 결과를 얻는데 중점을 두었다. 그 결과 상호간의 간섭에 의해 발생되는 신호는 실제 보내고자 하는 신호의 대역과 매우 가깝게 있으며 그 크기는 보내고자 하는 신호의 특성에 따라 달라지는 것을 확인 할 수 있었다.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.99-107
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• 2017

This paper proposes a battery model coefficient correction method for improving the accuracy of existing lithium battery equivalent models. BMS(battery management system) has been researched and developed to minimize shortening of battery life by keeping SOC(state of charge) and state of charge of lithium battery used in various industrial fields such as EV. However, the cell balancing operation based on the battery cell voltage can not follow the SOC change due to the internal resistance and the capacitor. Various battery equivalent models have been studied for estimation of battery SOC according to the internal resistance of the battery and capacitors. However, it is difficult to apply the same to all the batteries, and it tis difficult to estimate the battery state in the transient state. The existing battery electrical equivalent model study simulates charging and discharging dynamic characteristics of one kind of battery with error rate of 5~10% and it is not suitable to apply to actual battery having different electric characteristics. Therefore, this paper proposes a battery model coefficient correction algorithm that is suitable for real battery operating environments with different models and capacities, and can simulate dynamic characteristics with an error rate of less than 5%. To verify proposed battery model coefficient calibration method, a lithium battery of 3.7V rated voltage, 280 mAh, 1600 mAh capacity used, and a two stage RC tank model was used as an electrical equivalent model of a lithium battery. The battery charge/discharge test and model verification were performed using four C-rate of 0.25C, 0.5C, 0.75C, and 1C. The proposed battery model coefficient correction algorithm was applied to two battery models, The error rate of the discharge characteristics and the transient state characteristics is 2.13% at the maximum.

• Annual Conference on Human and Language Technology
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• 2003.10d
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• pp.173-176
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• 2003

본 논문은 언어학적 데이터로부터 자동으로 온톨로지를 생성하기 위한 모델을 제안하고 이를 구현한다. 모델 제안을 위해 온톨로지의 기본 구성 요소인 개념과 관계를 정의하고 이러한 개념과 관계 객체를 자동으로 추출하는 알고리즘을 제안한다. WordNet을 이용하여 개념을 자동으로 추출하고, 추출된 개념들간의 관계는 한국어의 구문적 특성을 이용하여 관계의 기본 형태를 정의하고 이를 기반으로 관계를 추출한다. 본 논문은 특허문서에서 전기통신기술문서를 대상으로 구현했으며, 제안된 알고리즘을 다른 영역으로 확장하여 이를 검증할 것이다.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.95-97
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• 2008

본 논문에서는 연료전지발전용 고효율 계통 연계용 전력변환기를 제안한다. 제안하는 전력변환기는 3상 전류형 능동클램프 DC/DC 컨버터와 계통연계용 인버터로 구성되어 있다. 제안하는 전력변환기의 동작을 분석하기 위해 연료전지의 출력을 모의하는 모델과 제안하는 전력변환기의 모델을 PSCAD/EMTDC를 이용하여 개발하였다. 개발한 시뮬레이션모델을 이용한 분석을 토대로 실험에 의한 검증이 가능한 하드웨어장치의 기본 설계를 실시하였다. 제안하는 전력변환기는 정격출력에서 저 전압특성을 갖는 연료전지를 효율적으로 전력계통에 연계하는데 유용할 것으로 보인다.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.74-82
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• 2013

This paper deals with a single stage coilgun which is a variety of EML(ElectroMagnetic Launcher) and can be applied to launching a small satellite. We propose a mathematical and physical model in order to design a single stage coilgun and study physical characteristics related to design parameters. A proposed mathematical and physical model is verified by electromagnetic FEM software FEMM 4.2.

• 한국IT서비스학회:학술대회논문집
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• 2002.11a
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• pp.7-15
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• 2002

인터넷포탈의 유료화는 인터넷포탈이 가지고 있는 취약한 수익모델을 개선하기 위하여 반드시 달성하여야 할 과제라고 할 수 있다. 인터넷포탈이 서비스를 유료화 하는 과정에서 인터넷포탈의 경쟁환경적 특성에 따라 수익모델을 발전시켜가는 방식으로서 묶음상품을 이용하는 원리와 그 가능성을 검증하고자 하였다. 국내 인터넷포탈은 이미 이용자의 니즈에 부합하는 다양한 형태의 묶음상품을 제공하고 있음을 확인할 수 있었으며, 인터넷포탈의 묶음상품 전략이 인터넷포탈의 경쟁력을 높일 수 있는 강력한 수단 또는 새로운 수익모델을 창출해 나가는 자기발전의 방식으로 활용될 수 있음을 관련문헌에 대한 연구와 국내사례를 통해 살펴보았다.