• 한국전기화학회:학술대회논문집
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• 2005.07a
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• pp.103-110
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• 2005

Fuel cell systems are consisted of various parts, for example fuel cell stack, fuel supplier, electrical converters, controllers and so on. Each components of system should have appropriate specification for their applications as well as simplicity. Because thermal load can be managed simply by using fans without any water cooling system, the air-cooled PEMFC is widely used in sub kW and around 1kW systems. The performance of an air-cooled system is highly dependent on ambient temperature and humidity. In this paper, the air-cooled PEMFC systems are developed and investigated to study the operating characteristics in the aspect of the thermal and water coupled management by the control of the axial fans and compressors. Various experiments were also conducted to get the cell voltage distribution, the relative humidity of the reactant gas and the thermal management by axial cooling fans, which cannot be observed in single cell experiment. After then, as practical applications, portable fuel cell system and a hybrid electric cart were successfully integrated and operated by using this air-cooled stack.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.5
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• pp.634-642
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• 1993

In this paper a new trajectory control method is proposed for a robot manipulator using a time delay neural network(TDNN) as a feedforward controller with an algorithm to learn inverse dynamics of the manipulator. The TDNN structure has so favorable characteristics that neurons can extract more dynamic information from both present and past input signals and perform more efficient learning. The TDNN neural network receives two normalized inputs, one of which is the reference trajectory signal and the other of which is the error signals from the PD controller. It is proved that the normalized inputs to the TDNN neural network can enhance the learning efficiency of the neural network. The proposed scheme was investigated for the planar robot manipulator with two joints by computer simulation.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.287-295
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• 2005

A Study on the Countermeasures against International Computer Crime focusing on the Police Investigation Procedure. These days, much more intelligent, varied and advanced techniques for computer crimes have been used than for development of technology. In particular, it has been reported that the damages are enormous. Damages of some computer crimes can not be accurately reported. This study is to speculate specific types of computer crimes and obtain its prevention and countermeasures centering on the Police Investigation Procedure. In particular, it is to speculate international cooperation under the condition that global damages occur frequently due to preparation of advanced network environment.

• The Korean Journal of Applied Statistics
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• v.33 no.1
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• pp.25-46
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• 2020

This paper presents ordinal probit semiparametric regression models using Bayesian Spectral Analysis Regression (BSAR) method. Ordinal probit regression is a way of modeling ordinal responses - usually more than two categories - by connecting the probability of falling into each category explained by a combination of available covariates using a probit (an inverse function of normal cumulative distribution function) link. The Bayesian probit model facilitates posterior sampling by bringing a latent variable following normal distribution, therefore, the responses are categorized by the cut-off points according to values of latent variables. In this paper, we extend the latent variable approach to a semiparametric model for the Bayesian ordinal probit regression with nonparametric functions using a spectral representation of Gaussian processes based BSAR method. The latent variable is decomposed into a parametric component and a nonparametric component with or without a shape constraint for modeling ordinal responses and predicting outcomes more flexibly. We illustrate the proposed methods with simulation studies in comparison with existing methods and real data analysis applied to a Korean National Health and Nutrition Examination Survey (KNHANES) 2016 for investigating nonparametric relationship between smoking behavior and coffee intake.

• The Korean Journal of Applied Statistics
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• v.18 no.1
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• pp.83-98
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• 2005

Exploring distributional patterns of multivariate data is very essential in understanding the characteristics of given data set, as well as in building plausible models for the data. For that purpose, low-dimensional visualization methods have been developed by many researchers along various directions. As one of methods, Kohonen's SOM (Self-Organizing Map) is prominent. SOM compresses the volume of the data, yields abstraction from the data and offers visual display on low-dimensional grids. Although it is proven quite effective, it has one undesirable property: SOM's display is discrete. In this study, we propose two techniques for enhancing quality of SOM's display, so that SOM's display becomes continuous. The proposed methods are demonstrated in two numerical examples.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.738-745
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• 2001

In this paper, when the moving object move to the three-dimentional space, the tracking system track the moving object using the fuzzy reasoning. The joint angle el of the manipulator rotate from $0^{\circ}\; to\; 360^{\circ}$ , and the joint angle $\theta_2$rotate from$0^{\circ}\; to\; 360^{\circ}$. The fuzzy singleton is used for fuzzification and the control rule is twenty five and the fuzzy inference method is simplified Mamdani's reasoning and the defuzzification is the SCOG(Simplified Center Of Gravity) of the fuzzy controller To measure of the performance of the designed system, the fuzzy controller is compared with the CTM(Computed Torque Method) controller at the same condition. when the disturbance torque is ON, the both of CTM and fuzzy controller tracked object without error, However, the disturbance torque changed 0.4N, the CTM controller is 10 times greater than fuzzy controller at the sum of absolute error difference. The designed system is showed it's robustness against with disturbance.

• Journal of the Korean Ceramic Society
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• v.40 no.9
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• pp.897-901
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• 2003

The sulfating reaction of coal fly ash with ammonium sulfate and the microwave extraction of aluminum ions from the resultant materials using sulfuric acid have been investigated. The (NH$_4$)$_3$Al(SO$_4$)$_3$ formed by the reaction of coal fly ash and ammonium sulfate decomposed to NH$_4$Al(SO$_4$)$_2$ at $\geq$ 350$^{\circ}C$. The maximum efficiency of aluminum ions extracted from the sulfating reaction product (400$^{\circ}C$, 120 min) by microwave heating (90$^{\circ}C$, 240 min) using 1 M H$_2$SO$_4$ was 84％ (based on Al content in coal fly ash) but 77％ by conventional heating at same condition.

• Journal of Animal Environmental Science
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• v.15 no.3
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• pp.271-280
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• 2009

The best way to treat livestock manure is to recycle as much as possible. The composting of livestock manure is a safe and economical treatment process. This study was carried out to investigate decomposition effect of pig manure by adding fermented compost. The fermented compost was added in pig manure mixed with sawdust as an inoculator, and the mixture was fed to composting reactor. Supplemental levels of fermented compost on the pig manure mixed with sawdust were regulated at 5, 10, 15 and 20% (V/V) respectively. The results were as follows ; 1. In all cases, PH range was between 7.6~9.05 during composting period. 2. The highest temperature and the long duration of thermophilic stage were observed in control treatment. 3. The number of microorganism reached at maximum on day 4, which recorded the highest temperature 4. Compost pile mixed with 10% of inoculator (fermented compost) showed the highest C/N ratio reduction.

• Annual Conference on Human and Language Technology
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• 1996.10a
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• pp.497-506
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• 1996

한국어에서 보조용언은 본용언에 연속적으로 연결되어 나타나서 많은 문법적 기능을 담당하고 화자의 양태 관계를 나타낸다. 그 중에서 사동 보조 용언과 파동 보조 용언이 본용언에 결합되었을 때는 본용언의 하위 범주화 값이 달라지며 문장에서 각 성분들의 의미역할이 바뀌게 된다. 따라서 자연어 이해와 기계번역의 질적 향상을 위해 이들에 대한 정확한 분석이 요청된다. 본 논문에서는 한국어 구문분석에서 보조 용언 처리의 한 부분으로서 사동 보조 용언 '-게 하-'로 실현되는 사동문과 피동보조 용언 '-아/어 지-'로 실현되는 피동문의 구문분석 방법을 제안한다. 사동문에서는 오분석을 막기 위해 사동 보조 용언이 아닌 '-게 하-' 구성을 구별해 내고, 피동문에서는 '-아/어 지-'를 피동보조용언과 기동상으로 분리시킨다. 그리고 이들 보조 용언으로 실현되는 사동/피동문을 격표지 정보와 사동문 분석 규칙, 피동문 분석규칙을 이용하여 사동/피동문이 가지는 의미특성을 나타낸 구문분석 결과를 제시한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.931-940
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• 2001

In this paper, I propose Fuzzy Policing Mechanism(FPM) over ATM networks for the control of traffic which is unpredictable and bursty source. The FPM is consist of counter, subtracter and Fuzzy Logic Controller(FLC). The FLC is divided to fuzzifier, inference engine and defuzzifer The output of FLC inputs to the subtractor and it controls the counter. The counter works as a switch in transmission of cells. In simulation, I compared the FPM with the Leaky Bucket algorithm(LBM) in cell loss probability and performance characteristics. As a result, FPM gives lower cell loss probability than that of LBM and has good response behavior The FPM efficiently controls the transmission of packets which are variable traffic source and, it also has good selectivity.