• 대기
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• 제17권1호
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• pp.1-15
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• 2007

A constraint based on climatology is introduced to the cost function of the three-dimensional variational assimilation (3dVar) to correct the error of the zonal mean wind structure in the global data assimilation system at Korea Meteorological Administration (KMA). The revised cost function compels the analysis fit to the chosen climatology while keeping the balance between the variables in the course of analysis. The constraint varies selectively with the vertical level and the horizontal scale of the motion. The zonally averaged wind field from European Centre for Medium-Range Weather Forecasts Re-Analysis 40 (ERA-40) is used as a climatology field in the constraint. The constraint controls only the zonally averaged stratospheric long waves with total wave number less than 20 to fix the error of the large scale wind field in the stratosphere. The constrained 3dVar successfully suppresses the erroneous westerly in the stratospheric analysis promptly, and has been applied on the operational global 3dVar system at KMA.

• 대한기계학회논문집A
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• 제29권2호
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• pp.188-200
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• 2005

Control of a multi-fingered robotic hand is usually based on the theoretical analysis for kinematics and dynamics of fingers and of object. However, the implementation of such analyses to robotic hands is difficult because of errors and uncertainties in the real situations. This article presents the control method for estimating the kinematic constraint of an unknown object by active sensing. The experimental system has a two-fingered robotic hand suspended vertically for manipulation in the vertical plane. The fingers with three degrees-of-freedom are driven by wires directly connected to voice-coil motors without reduction gears. The fingers are equipped with three-axis force sensors and with dynamic tactile sensors that detect slippage between the fingertip surfaces and the object. In order to make an accurate estimation for the kinematic constraint of the unknown object, i.e. the constraint direction and the constraint center, four kinds of the active sensing and feedback control algorithm were developed: two position-based algorithms and two force-based algorithms. Furthermore, the compound and effective algorithm was also developed by combining two algorithms. Force sensors are mainly used to adapt errors and uncertainties encountered during the constraint estimation. Several experimental results involving the motion of lifting a finger off an unknown object are presented.

• Structural Engineering and Mechanics
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• 제54권6호
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• pp.1153-1174
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• 2015

Deployable structures have gained more and more applications in space and civil structures, while it takes a large amount of computational resources to analyze this kind of multibody systems using common analysis methods. This paper presents a new approach for dynamic analysis of multibody systems consisting of both rigid bars and arbitrarily shaped rigid bodies. The bars and rigid bodies are connected through their nodes by ideal pin joints, which are usually fundamental components of deployable structures. Utilizing the Moore-Penrose generalized inverse matrix, equations of motion and constraint equations of the bars and rigid bodies are formulated with nodal Cartesian coordinates as unknowns. Based on the constraint equations, the nodal displacements are expressed as linear combination of the independent modes of the rigid body displacements, i.e., the null space orthogonal basis of the constraint matrix. The proposed method has less unknowns and a simple formulation compared with common multibody dynamic methods. An analysis program for the proposed method is developed, and its validity and efficiency are investigated by analyses of several representative numerical examples, where good accuracy and efficiency are demonstrated through comparison with commercial software package ADAMS.

• 한국CDE학회논문집
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• 제6권2호
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• pp.78-88
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• 2001

In order to adopt feature-based parametric modeling, CAD/CAM applications must have a geometric constraint solver that can handle a large set of geometric configurations efficiently and robustly. In this paper, we describe a graph constructive approach to solving geometric constraint problems. Usually, a graph constructive approach is efficient, however it has its limitation in scope; it cannot handle ruler-and-compass non-constructible configurations and under-constrained problems. To overcome these limitations. we propose an algorithm that isolates ruler-and-compass non-constructible configurations from ruler-and-compass constructible configurations and applies numerical calculation methods to solve them separately. This separation can maximize the efficiency and robustness of a geometric constraint solver. Moreover, the solver can handle under-constrained problems by classifying under-constrained subgraphs to simplified cases by applying classification rules. Then, it decides the calculating sequence of geometric entities in each classified case and calculates geometric entities by adding appropriate assumptions or constraints. By extending the clustering types and defining several rules, the proposed approach can overcome limitations of previous graph constructive approaches which makes it possible to develop an efficient and robust geometric constraint solver.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.953-956
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• 2000

Application specific DSPs often employ irregular datapath structures with distributed registers. In the scheduling phase of retargetable compilation, resolution of register usage conflicts comes to be a new constraint for such datapaths. This paper presents a method of register constraint analysis which attempts to minimize the number of the spill codes required for resolving the register usage conflicts. It searches for a set of ordering restrictions among operations which sequentialize the lifetimes of the values residing in the same register as much as possible and thus minimize the number of the register conflict. Experimental results show that a combination of the proposed register constraint, analysis and list-based scheduling reduces the number of the register spills into 25%.

• 한국콘텐츠학회논문지
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• 제13권7호
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• pp.386-394
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• 2013

본 연구는 스키 참가자들의 여가제약 협상 수준에 따른 레크리에이션 전문화의 차이와 여가제약 협상이 레크리에이션 전문화에 미치는 영향을 규명하는데 그 목적이 있다. 경기도와 강원도에 위치한 4개 스키리조트를 방문하는 18세 이상의 성인 남녀를 모집단으로 설정하였고, 군집표집법을 이용하여 표본을 추출하였다. 총 400부의 설문지를 배포하였고 374부가 최종분석에 활용되었다. 여가제약 협상전략을 활용하는 참여자는 강도와 정도에 따라 3개의 집단으로 분류하였고 여가제약 협상 수준에 따른 레크리에이션 전문화의 하위요인별로 일원변량분석과 회귀분석을 실시하여 다음과 같은 결론을 도출하였다. 첫째, 여가제약 협상은 전략을 활용하는 강도와 정도에 따라 상, 중, 하의 3단계로 분류가 되었다. 둘째, 여가제약 협상 수준에 따른 레크리에이션 전문화는 전체평균에서 차이가 나타났으며, 여가제약 협상전략을 적극적으로 활용하는 집단이 그렇지 않은 집단에 비해 과거경험, 인생의 구심성, 경제적 투자 등의 전문화 하위요인에서 높은 평균을 나타냈다. 셋째, 여가제약 협상전략의 적극적인 활용은 레크리에이션 전문화에 정적 영향을 미치는 것으로 나타났다.

• International Journal of Contents
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• 제6권2호
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• pp.59-68
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• 2010

This research looks close the effect of security agent's hierarchical leisure constraint on the leisure motivation and participation based on the Jackson's Model of the hierarchical leisure constraints. This research selected 420 people for sampling, designating security agents who work for security companies located in Seoul in 2009 at present as subjects by utilizing purposive sampling method, but the number of sampling used for ultimate analysis is 356. In this research, reliability analysis's and structural equation modeling's Maximum Likelihood method are used to prove the reliability and validity of questionnaire. By using these research method and procedures, the conclusion of this research is as following. First, intra-personal leisure constraint was affected by interpersonal, structural leisure constraint. Second, leisure motivation was affected negatively by leisure constraint. Third, leisure participation was affected positively by leisure motivation. Synthesizing all things referred above, leisure constraint was affected by inter-personal, structural leisure constraint, and in turn, leisure motivation and leisure participation were affected by its effects. It turned out that leisure motivation has a meaningful effect on leisure participation through leisure participation and adjusting process.

• 한국경영정보학회:학술대회논문집
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• 한국경영정보학회 2007년도 International Conference
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• pp.509-514
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• 2007

Most of the IS continuance research has assumed that IS use is activated by an intention to use, which in turn is determined by the evaluation of IS usage. Perceived usefulness is one of the evaluation variables most widely used. Typically, the past studies adopt this perceived usefulness because it views continuance as an extension of acceptance behavior. However, the literature on interpersonal relationships suggests that individuals are motivated to maintain relationships either because they genuinely want to or they believe they have no other option. The former is referred to as dedication-based relationship maintenance and the latter as constraint-based relationship maintenance. The IS continuance can be considered as the relationship maintenance situation with the existing IS that the user is currently using. The belief constructs previously used in IS continuance researches fall into the category of dedication-based ones. Additional constraint-based belief constructs are needed to explain the IS continuance behavior. In this regard, switching cost represents an important avenue for better understanding and predicting customer retention in that it can be regarded as the constraint-based motivation for relationship maintenance or IS use continuance. For an empirical exploration, 275 samples were collected from the users of a web portal site. Data analysis using Structural Equation Modeling (SEM) shows that perceived usefulness shows a significant direct effect on continuance intention while perceived switching cost significantly affects continuance usage.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.93-98
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• 2002

This study presents a new method to derive the constraint coefficient from the degree of angular deformation caused by welding, as measured experimentally by varying the shape of welded joints and the magnitude of constraints and from analysis results given by the elastic FEM method. The equivalent load was then calculated with this constraint coefficient. The validity of the numerical analysis involved in this new method was confirmed by its agreement with the experimental results. As for the effects of the constraints based on the shape of the welded joints in the case of Butt welding when the constraint coefficients are not considered, the deformed quantity produced by analysis is larger that produced by experiment and consequently is largely affected by the constraints.

• 한국콘텐츠학회논문지
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• 제10권4호
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• pp.359-366
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• 2010

이 연구의 목적은 민간경비원의 여가제약이 직무스트레스 및 생활만족에 미치는 영향을 규명하는데 있다. 이 연구는 2009년 서울소재 민간경비 회사에 재직하고 있는 민간경비원들을 연구대상으로 판단표집법을 이용하여 최종분석에 사용된 사례 수는 300명이다. 수집된 자료는 SPSSWIN 17.0을 이용하여 요인분석, 신뢰도분석, 회귀분석, 경로분석 등의 방법을 활용하였다. 설문지의 신뢰도는 Cronbach's $\alpha$값이 .600 이상으로 나타났다. 본 연구의 결론은 다음과 같다. 첫째, 민간경비원의 여가제약은 직무스트레스에 영향을 미친다. 즉, 주변 의식적 제약, 개인적 제약이 증가하면 직무스트레스는 높아지는 반면, 대인적 제약이 감소하면 직무스트레스는 낮아진다. 둘째, 민간경비원의 여가제약은 생활만족에 영향을 미친다. 즉, 개인적 제약이 감소하면 생활만족감은 높아진다. 셋째, 민간경비원의 직무스트레스는 생활만족에 영향을 미친다. 즉, 보상 및 경력개발이 증가하면 생활만족감은 높아지는 반면, 직무특성이 감소하면 생활만족감은 낮아진다. 넷째, 민간경비원의 여가제약은 직무스트레스 및 생활만족에 인과적 영향을 미친다. 즉, 직무스트레스는 여가제약과 생활만족의 관계를 매개하는 중요한 변수임을 알 수 있다.