• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1378-1383
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• 2003

A ferroelectric (called piezoelectric afterwards) wafer has been widely used as a key component of actuators or sensors of a layer type. According to recent researches, the piezoelectric wafer behaves in a nonlinear way under excessive electro-mechanical loadings. In the present paper, one-dimensional constitutive equations for the nonlinear behavior of a piezoelectric wafer are proposed based on the principles of thermodynamics and a simple viscoplasticity theory. The predictions of the developed model are compared with experimental observations.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.232-234
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• 2002

EEG-based brain computer interface (BCI) provides a new communication channel between human brain and computer. The classification of EEG data is an important task in EEG-based BCI. In this paper we present methods which jointly employ principal component analysis (PCA) and linear dynamical system (LDS) modeling for the task of EEG classification. Experimental study for the classification of EEG data during imagination of a left or right hand movement confirms the validity of our proposed methods.

• Journal of the Korean Data and Information Science Society
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• v.21 no.2
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• pp.379-385
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• 2010

This paper considers Bayesian approach to modeling a flexible regression function under functional measurement error model. The regression function is modeled based on semiparametric regression with penalized splines. Model fitting and parameter estimation are carried out in a hierarchical Bayesian framework using Markov chain Monte Carlo methodology. Their performances are compared with those of the estimators under functional measurement error model without semiparametric component.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.587-589
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• 1999

최근 급부상하고 있는 분산 환경에서의 소프트웨어 개발 방법을 점검해 보고 특정 웹 서버를 기반으로 하는 웹 컨텐츠 개발 과정의 문제점을 파악하여 웹 컨텐츠 유지보수 및 재사용에 도움을 줄 수 있는 컴포넌트 기반 웹 컨텐츠 개발 프로세스를 제시하고 분석 단계를 통해서 분산된 웹 환경에 적합한 Rapid Prototype을 Use Case 모델링을 중심으로 구축하여 웹 기반 채팅 서비스를 사례 연구로 적용해 본다.

• The KIPS Transactions:PartD
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• v.14D no.1 s.111
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• pp.83-88
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• 2007

In this paper, we introduce MDA based Development Method for Embedded Software Component. This method applies MDA approach to solve problems about reusability of the heterogeneous embedded software system. With our proposed method, we produce 'Target Independent Meta Model'(TIM) which is transformed into 'Target Specific Model'(TSM) and generate 'Target Dependent Code' (TDC) via TSM. We would like to reuse a meta-model to develop heterogeneous embedded software systems. To achieve this mechanism, we extend xUML to solve unrepresented elements (such as real things about concurrency, and real time, etc) on dynamic modeling of the particular system. We introduce 'MDA based Embedded S/W Modeling Tool' with extended XUML. With this tool, we would like to do more easily modeling embedded or concurrent/real time s/w systems. It contains two examples of heterogeneous imbedded systems which illustrate the proposed approach.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.6
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• pp.554-564
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• 2020

In environment of torpedo firing, underwater acoustic signal is generated by target and noise. Sound wave which is generated from acoustic signal is propagated by seawater and it is received through the sonar(sound navigation and ranging) system mounted on torpedo. In the ocean, acoustic signal or sound wave from target that is generated by the spread of broadband can be attenuated by ambient noise and can be lost by medium and environment. This research is designed to support teamwork training in Naval operations by constructing a simulation system that is more similar to the real-world conditions. This paper attempts to research the modeling of target detection and to develop the simulation of torpedo sonar(TOSO). In order to develop the realistic simulation, we researched the broadband sound modeling of target and noise source, the modeling of acoustic transmission loss by chemical component of seawater, and the modeling of signal attenuation by ambient noise environment which is approximated by experimental measurements in seawater surrounding the Korea Peninsular and by experience of Navy's actual torpedo firing. This research contributed to constructing more practical simulation of torpedo firing in real time and the results of this research were used to develop a teamwork training system for the Navy and their education.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.220-229
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• 1997

Extraction of valuable light hydrocarbon from atmospheric residue using pentane as a solvent has been carried out. The SIMDIS was used to calculate the true boiling point of atmospheric residue containing complex components before the modeling of the extraction process could by performed. In order to simplify the procedure, modeling was adopted and a lumping method was used, such that a large number of compounds were divided into similar component classes called pseudocomponents. The modeling of the extraction process of the atmospheric residue-pentane system was based on the isothermal flash calculation, and the Peng-Robinson equation of state was used to calculate the fugacity coefficient of vapor and liquid phase during calculation steps of modeling. The agreement between the experiments and the calculations was reasonable considering the uncertainties involved in modeling such complex processes.

• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.53-63
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• 2016

This study aims to verify the feasibility of design by developing pressure flow-controlled swash plate type pump with the use of SimulationX, a computer analysis program. Developing analysis model based on design drawing data has a cost-saving effect because it is possible to figure out the effectiveness of design through the work and it never falls into repeated inaccuracies in the production process. Analysis model is developed in the following order. First, the structure of each part such as valve and rotating unit which have dynamic factor is analyzed and the modeling of single component is carried out, reflecting drawing data. Second, the modeling of pump assembly is carried out with the combination of each analysis model and a work is conducted to determine whether the modeling can perform pressure flow control function according to load condition smoothly based on design intent. At the end of the modeling process, the feasibility of design is verified by showing the parts which are moving as expected mechanism.

• Investigative Magnetic Resonance Imaging
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• v.3 no.2
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• pp.188-195
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• 1999

The fMRI signals are composed of many various signals. It is very difficult to find the accurate parameter for the model of fMRI signal containing only neural activity, though we may estimating the signal patterns by the modeling of several signal components. Besides the nose by the physiologic motion, the motion of object and noise of MR instruments make it more difficult to analyze signals of fMRI. Therefore, it is not easy to select an accurate reference data that can accurately reflect neural activity, and the method of an analysis of various signal patterns containing the information of neural activity is an issue of the post-processing methods for fMRI. In the present study, fMRI data was analyzed with the Independent Component Analysis(ICA) method that doesn't need a priori-knowledge or reference data. ICA can be more effective over the analytic method using cross-correlation analysis and can separate the signal patterns of the signals with delayed response or motion related components. The Principal component Analysis (PCA) threshold, wavelet spatial filtering and analysis of a part of whole images can be used for the reduction of the freedom of data before ICA analysis, and these preceding analyses may be useful for a more effective analysis. As a result, ICA method will be effective for the degree of freedom of the data.

• Information Systems Review
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• v.4 no.2
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• pp.209-222
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• 2002

EDI (Electronic Data Interchange) has been widely utilized to support Business Activities since it has such advantages as fast transfer of information, less documentation work, efficient information exchange etc. Recently e-business environment has urged the traditional EDI system to be changed to ebXML framework. To apply the ebXML framework to a certain industry, it is required to implement Business Process (BP), Core Component (CC), Collaboration Protocol Profile (CPP), Collaboration Protocol Agreement (CPA), Messaging system etc. We have selected the port and logistics industry as a target domain to apply ebXML framework, since the EDI usage ratio of it is relatively higher than other industries. In this paper, we have analyzed the current status of EDI system and transaction processes in the port and logistics industry. We have defined the business process that will be registered in the registry/repository, the main component of ebXML framework, using UN/CEFACT modeling methodology. And Business Collaborations, Business Transactions, Business Document Flows, Choreography, Pattern, etc. are represented using UML according to UN/ CEFACT modeling methodology, to apply ebXML Framework to the port and logistics distribution industry. Also we have suggested the meta methodology for applying the ebXML framework to other industries.