• Journal of Korean Society of Transportation
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• v.20 no.6
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• pp.129-140
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• 2002

This paper develops a dynamic structural equation model, which captures relationships among socio-demographics, activity participation(i.e., time use) and travel behavior in consideration with time variation effects. The data used in developing the model are two waves(the year 1991 and 1992) from Puget Sound Transportation Panel (PSTP). which is surveyed in Puget Sound Region in United States. The PSTP is widely used in transportation behavior analysis and includes various information of traveler's socio-economic, travel patterns, and activity participation. In the model, we use 10 endogenous variables including activity participations and travel behaviors and 10 exogenous variables composed of time variant and invariant traveler's socio-demographic variables. The empirical model shows that strong relationships exist not only between socio-demographics and travel behavior, but between waves. We also confirm needs of panel data set to identify and understand time variation effects and travel behaviors.

• Proceedings of the Korean Society for Information Management Conference
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• 1998.08a
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• pp.133-136
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• 1998

본 연구는 대학도서관의 효율적인 조직구조의 형성방안을 위하여 대학 도서관 조직구조의 상황변수, 기본변수, 구조형태 및 조직유효성 간에 상호영향을 미치는 요인을 규명하고자 한 것으로서 이론적인 배경을 토대로 연구모형을 설계한 후에 실증적인 검증을 시도하였다. 이 검증을 위하여 상황변수는 환경, 기술, 규모, 전략유형, 권력유형을 채택하고, 기본변수는 복잡화, 공식화, 집권화를 채택하였으며, 구조형태는 단순조직, 기능별조직, 분관조직, 주제별조직(I)(II)로 구분하였고, 조직유효성 변수는 능률성, 유연성, 정보자료관리 및 만족성을 채택하였으며, 만족성은 조직몰입과 직무만족으로 세분하였다. 연구결과 조직구조의 상황변수, 기본변수 및 구조형태는 상호간에 영향을 주며, 궁극적으로 조직유효성에 영향을 주지만 그 내용은 극히 미약한 것으로 나타났다. 그리고 모든 측면에서 조직유효성이 높은 조직은 없고, 조직유효성에 영향을 미치는 구조형태는 극히 미약한 것으로 분석되었다.

• Journal of Families and Better Life
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• v.13 no.3
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• pp.134-143
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• 1995

본 연구는 부채농가의 재정향상을 위한 경제적 대처행동의 양상과 그 관련요인을 규명하고자 하였다. 이를 위해 충남지역 농촌가계들을 대상으로 수집한 자료를 이용하였는데 대처행동을 파악하기 위해서 요인분석을 대처행동에 대한 부채관련변수의 관련성을 보기 위해서 분산분석을, 관련변수들의 독립적인 영향력을 검증하기 위해서는 중회귀분석을 시행하였다. 주요 연구결과는 다음과 같다. (1) 농촌가계의 경제적 대처행동은 6개 속성으로 분류되 었으며 '소극적 노력', '절약 및 노동력활용', '적극적노력', '재정관리', '의존적 행동', '한계적 행동'의 순으로 자주 수행하는 것으로 밝혀졌다. (2) 부채관련변수 중에서 총부채액, 부채부담, 부채부담감은 각 대처행동에 대해서 다소 다른 관계를 보였다. 소득대비 부채상환액과 소득 대비 부채상환요구액으로 측정한 부채부담은 대처행동에 대해서 그 효과가 서로 다르게 나타났다. (3) 대처행동에 대한 독립적인 영향요인으로 밝혀진 부채관련변수와 소득 및 자산관련변수, 인구통계적 특성변수, 환경적 특성변수들은 각 행동에 대해 그 영향력이 다르게 나타났다.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.3
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• pp.49-56
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• 2009

Recently, a generation of high quality mosaic images from video sequences has been attempted by a variety of investigations. Among the matter of investigation, in this paper, generation on stereo mosaic utilizing airborne-video sequence images is focused upon. The stereo mosaic is made by creating left and right mosaic which are fabricated by front and rear slices having different viewing angle in consecutive video frames. For making the stereo mosaic, motion parameters which are able to define geometric relationship between consecutive video frames are determined. For determining motion parameters, affine model which is able to explain relative motion parameters is applied by this paper. The mosaicing method using relative motion parameters is called by free mosaic. The free mosaic proposed in this paper consists of 4 step processes: image registration with reference to first frame using affine model, front and rear slicing, stitching line definition and image mosaicing. As the result of experiment, the left and right mosaic image, anaglyphic image for stereo mosaic images are showed and analyzed y-parallax for checking accuracy.

• The Korean Journal of Financial Management
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• v.17 no.1
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• pp.137-159
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• 2000

재무경제학에서 많은 연구들이 주식가격과 거시경제활동과의 이론적 모형을 설정하고 이를 점증하고자 하였다. 이 분야에서 지금까지 주로 ARMAX 모형이나 VAR 모형들이 사용되어 왔으나, 이러한 방법들은 주식가격과 거시경제변수들간의 장기적인 균형관계를 파악할 수 없다는 한계점을 안고 있다. 따라서, 본 연구의 목적은 이러한 한계점을 극복할 수 있는 VECM을 이용하여 우리나라 증권시장과 거시경제변수들간의 장기적인 균형관계를 규명하고자 함에 있다. 검증결과, 모든 변수들의 시계열이 불안정적인 것으로 확인된 관계로, 다변량시계열의 공적분 관계를 검증하는 Johansen 검증을 VECM 모형의 구조 안에서 실시하였다. 종합주가지수와 거시경제변수들간에는 장기적 안정관계를 나타내는 공적분관계가 있는 것으로 나타났으며, 종합주가지수와 거시경제변수들간의 관계는 대부분 이론적인 관계에서 예상하는 부호와 동일한 부호를 갖으며 통계적으로도 유의하였다. 그리고, VECM의 설명력이 종래에 주로 사용하였던 VAR 모형의 설명력보다 더 우월하게 나타났다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.7
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• pp.1156-1165
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• 1997

Complex modal testing is employed for the in-situ parameter identification of a four-axis active magnetic bearing system while the system is in operation. In the test, magnetic bearings are used as exciters as well as actuators for feedback control. The experimental results show that the directional frequency response function, which is properly defined in the complex domain, is a powerful tool for identification of bearing as well as modal parameters. It is also shown that the position and current stiffnesses can be accurately estimated using the relations between the measured forces, displacements, and currents.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1593-1600
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• 2000

A method based on frequency domain approaches is presented for the nonlinear parameters identification of structure having nonlinear joints. The finite element model of linear substructure is us ed to calculating its frequency response functions needed in parameter identification process. This method is easily applicable to a complex real structure having nonlinear elements since it uses the frequency response function of finite element model. Since this method is performed in frequency domain, the number of equations required to identify the unknown parameters can be easily increased as many as it needed, just by not only varying excitation amplitude but also selecting excitation frequencies. The validity of this method is tested numerically and experimentally with a cantilever beam having the nonlinear element. It was verified through examples that the method is useful to identify the nonlinear parameters of a structure having arbitary nonlinear boundaries.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.7 s.112
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• pp.769-776
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• 2006

A measured frequency response function can be represented as a ratio of two polynomials. A curve-fitting of frequency responses with Legendre polynomialis suggested in the paper. And the suggested curve-fitting algorithm is based on the least-square error method. Since the Legendre polynomials satisfy the orthogonality condition, the curve-fitting with the polynomials results to more reliable curve-fitting than ordinary polynomial method. Though the proposed curve-fitting with Legendre polynomials cannot cover all frequency range of interest, example shows that the suggested method is quite applicable in a limited frequency band.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.11
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• pp.1112-1118
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• 2007

It was discussed to identify Thiele Small Parameters for Pseudo loudspeaker within 10mm grade microspeaker attached to closed-box using known dynamic mass of moving parts. Also, enhanced circuit model for vented-box micro speaker system was used to more accurately simulate electrical impedance curves for real vented-box microspeaker system and compared to test results. Consequently, it showed that micro speaker could be modeled by pseudo loudspeaker TS parameters similar to general loudspeaker. Vented-box microspeaker model with pseudo loudspeaker TS parameters was well suited to describe real microspeaker. Also, it was proposed to estimate volume of rear closed-box of microspeaker without design specifications.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.663-668
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• 2004

To model and understand the physics of partial rub, a nonlinear rotor model is investigated by applying nonlinear parameter identification technique to the experimental data. The results show that the nonlinear terms of damping and stiffness should be included to model partial rotor rub. Especially, the impact and friction during the contact between rotor and stator are tried to explain with the nonlinear model on the basis of experimental data. The estimated nonlinear model shows good agreements between numerical and experimental results in its orbit.