• Communications for Statistical Applications and Methods
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• 제21권5호
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• pp.445-459
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• 2014

This paper investigates the dependence structure of Korean financial markets (stock, foreign exchange (FX) rates and bond) using copula-GARCH and dynamic conditional correlation (DCC) models. We examine GJR-GARCH with skewed elliptical distributions and four copulas (Gaussian, Student's t, Clayton and Gumbel) to model dependence among returns, and then employ DCC model to describe system-wide correlation dynamics. We analyze the daily returns of KOSPI, FX (WON/USD) and KRX bond index (Gross Price Index) from $2^{nd}$ May 2006 to $30^{th}$ June 2014 with 2,063 observations. Empirical result shows that there is significant asymmetry and fat-tail of individual return, and strong tail-dependence among returns, especially between KOSPI and FX returns, during the 2008 Global Financial Crisis period. Focused only on recent 30 months, we find that the correlation between stock and bond markets shows dramatic increase, and system-wide correlation wanders around zero, which possibly indicates market tranquility from a systemic perspective.

• 전기학회논문지
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• 제58권6호
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• pp.1200-1206
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• 2009

In this study, a new method of dental plaque scoring is proposed by adopting new criteria to divide the tooth surface with utilizing the geometrical features of a tooth color image. For the possible clinical usage of our new plaque scoring system, GUI(Graphic User Interface) system is also implemented to estimate the numerical plaque index for a specific tooth by designing the supplementary database management module that handles dental plaque scores.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 2부
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• pp.136-139
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• 2008

다양한 기능들이 휴대폰에 집약되고 있음에 따라, 사용자가 메뉴를 간편하게 선택할 수 있도록 도와주는 pointing Device의 역할은 매우 중요해지고 있다. 본 연구는 휴대폰에 내장된 pointing device 중 광센서와 pointing stick에 대한 사용성 평가를 통한 사용자의 조작 효율 및 조작 만족도 향상 요인 도출을 목적으로 하고 있다. 이를 위하여 본 연구에서는 각각의 입력장치가 적용된 휴대폰을 이용하여 객관적 평가와 주관적 평가를 수행하였다. 객관적 평가에서는 Fitts' law를 바탕으로 한 throughput 개념을 이용하여 커서 이동 및 선택 성능을 평가하였다. 또한 주관적 병가에서는 체크리스트를 이용하여 사용자의 수용도(user acceptance)를 평가하였다. 연구 결과, 광센서는 이동 방향에 따라 수행도 차이가 큰 것으로 나타났으며, pointing stick가 광센서에 비해 사용자의 수용도가 높게 나타났다. 본 연구 결과는 추후 실제 휴대폰의 pointing Device 설계 및 적용 시에 유용하게 활용될 수 있을 것이라 예상된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.172.2-172
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• 2001

We introduce a new stable feedback controller eventually converges to a conventional SDRE(State Dependent Riccati Equation) based optimal (suboptimal) controller. On conventional SDRE, the optimal control input should be obtained by backward integration of the SDRE at each control point. The proposed controller is given by direct forward integration of a proposed SDRE. This fact enables fast computation and easy implementation. On concerning a state dependent system, the proposed controller may be a candidate to the conventional SDRE based optimal controller if the system is slow varying with states. Though the controller is fast and easy to implement it is not able to cope with a fast varying system. We introduce an optimality index, which indicates how far the proposed controller is deviated from the solution of the convectional SDRE. If the index escapes a ...

• 한국컴퓨터정보학회논문지
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• 제22권8호
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• pp.73-83
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• 2017

In this paper, we discuss the differences between an ordinary B-tree and B-tree implemented by NTFS. There are lots of distinctions between the two B-tree, if not understand the distinctions fully, it is difficult to utilize and analyze artifacts of NTFS. Not much, actually, is known about the implementation of NTFS, especially B-tree index for directory management. Several items of B-tree features are performed that includes a node size, minimum number of children, root node without children, type of key, key sorting, type of pointer to child node, expansion and reduction of node, return of node. Furthermore, it is emphasized the fact that NTFS use B-tree structure not B+structure clearly.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.594-599
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• 2007

According to separation policy between rail infrastructure and operation, the National Railroad Administration was converted to Korea Railroad Cooperation on Jan, 2005. That makes railway service assessment regarded as essential. About this matter, Section 15 of the Framework Act on Rail Industry Development and section 26 of the Rail Business Act shows that the railway service assessment should be conducted every 2 years. The government can officially announce the result and give orders operation company to improve service level. In the first railway service assessment in 2006, the principal railroad lines and stations were investigated. Rail supply service index and customer satisfaction index are introduced. It includes service items of supply, reliability, convenience, safety and customer satisfaction. This study presents the contents of 2006 rail service assessment. Some points of assessment which should be improved are analyzed as well.

• 한국생산제조학회지
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• 제5권4호
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• pp.7-16
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• 1996

The dynamic model of the suspension system is developed by using both sky-hook control and output feedback control techniques. based on the performance sensitivity index, Many vehicles use sky-hook control theory operated with only one sensor, due to relatively low cost and easy implementation. On the other hand, output feedback control implemented with state variables has difficulties in measuring such as tire deflection, etc.

• 한국생산제조학회지
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• 제21권1호
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• pp.58-64
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• 2012

Instead of the surface pattern arranged repeatedly in two axial direction on a plane, we propose double patterns superposing two one-axial linear patterns as a reference target for surface encoding. A upper layer of the superposed pattern is the transparent glass with grooves cut in it at a fixed pitch. The position is sensed by detecting a shift of beam due to difference of a refractive index. And a lower layer is the aluminum with color-coated grooves. The amount of beam reflected on the layer varies according to its targeting position and is detected for encoding. For the above reference pattern, we can detect two-axial positions using only the single beam. Furthermore, the pattern size can be expanded with a size of the detector kept constant, meaning that the measured range can be expanded easily. In this paper, we review the existing optical encoding methods for grid pattern, and discuss the hardware implementation of the suggested surface encoding method.

• 정보기술과데이타베이스저널
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• 제7권1호
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• pp.27-39
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• 2000

In this paper, we design and implement a XML management system based on OODBMS that supports structured information retrieval of XML documents. We also propose an object oriented modeling to store and fetch XML documents, to manage image data, and to support versioning for the XML document management system(XMS). The XMS consists of a repository manager that maintains the interfaces for external application programs, a XML instance storage manager that stores XML documents in the database, a XML instance manager that fetches XML documents stored in the database, a XML index manager that creates index for the structure information and the contents of documents, and a query processor that processes various queries.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.184-184
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• 2017

A nation-wide water-energy-food (WEF) nexus simulation model has been developed by the authors and successfully applied to South Korea to predict the sustainability of those three resources in the next 30 years. The model was also capable of simulating future scenarios of resources allocation based on priority rules aiming to maximize resources sustainability. However, the process was still relying on several assumptions and trial-and-error approach, which sometimes resulted in non-optimal solutions of resources allocation. In this study, an optimization module was introduced to enhance the model in generating optimal resources management rules. The objective of the optimization was to maximize the reliability index of resources by determining the resources' allocation and/or priority rules for each demand type that accordingly reflect the resources management policies. Implementation of the optimization module would result in balanced allocation and management of limited resources and assist the stakeholders in deciding resources' management plans, either by fulfilling the domestic production or by global trading.