• Structural Engineering and Mechanics
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• 제30권3호
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• pp.369-382
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• 2008

An oscillator of two lumped masses linked through a vertical spring moves forward in the horizontal direction, initially at a certain height, over a horizontal Euler beam and descends on it due to its own weight. Vibration of the beam and the oscillator is excited at the onset of the ensuing impact. The impact produced by the descending oscillator is assumed to be either perfectly elastic or perfectly plastic. If the impact is perfectly elastic, the oscillator bounces off and hits the beam a number of times as it moves forward in the longitudinal direction of the beam, exchanging its dynamics with that of the beam. If the impact is perfectly plastic, the oscillator (initially) sticks to the beam after its first impact and then may separate and reattach to the beam as it moves along the beam. Further events of separation and reattachment may follow. This interesting and seemingly simple dynamic problem actually displays rather complicated dynamic behaviour and has never been studied in the past. It is found through simulated numerical examples that multiple events of separation and impact can take place for both perfectly elastic impact and perfectly plastic impact (though more of these in the case of perfectly elastic impact) and the dynamic response of the oscillator and the beam looks noisy when there is an event of impact because impact excites higher-frequency components. For the perfectly plastic impact, the oscillator can experience multiple events of consecutive separation from the beam and subsequent reattachment to it.

• 전자공학회논문지CI
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• 제44권1호
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• pp.49-55
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• 2007

본 논문은 컴퓨터 바둑에서 계가 알고리즘의 방법을 제안한다. 제안된 방법은 안정도의 고려와 죽은 돌에 대한 처리 그리고 계가 알고리즘으로 이루어진다. 저자는 죽은 돌의 처리를 위한 방법과 빈 공배의 채움, 그리고 가일수에 대한 방법을 제안한다. 제안한 계가 알고리즘에서는 공배를 그룹의 영역에 포함되지 않은 빈 점으로 정의하고 가일수를 모든 공배를 채우는 과정에서 삶을 위해 강요되어지는 수로 정의한다. 362개의 종료된 게임을 사용하여 실험하였으며, 그 결과 CGoban, HandTalk과 제안한 방법에서 각각 8.66, 5.96 그리고 4.15의 평균 에러 값을 얻었다. 제안된 방법은 실험을 통해 종료된 게임에 성공적으로 적용됨을 검증한다.

• 대한한의학회지
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• 제26권4호
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• pp.162-167
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• 2005

According to the principle of ascending water and descending fire, water has the property of wetting downward, which is the opposite of fire, which has the property of blazing upward. Thus, they work differently according to their innate properties. Nature and the human body maintain harmony through the interaction of ascending water and descending fire. When applied to the human body, the heart and kidney are the center of this principle. In other words, the heart above is the fire and the kidney downward is water. When the heart-fire harmonizes downward, the kidney becomes warm, enabling genuine vital functions to be active. When the kidney yin moves upward, the heart receives the nourishing yin to harmonize nutrients and blood. Thereby, physiological functions become normal throughout the blood meridians. However, in the ascending kidneywater and descending heart-yang of the heart and the kidney, the liver and lung are the major functional organs. In other words, the liver through the dispersing and raising yang functions moves water, which is the vital essence of the kidney, upward. And the lung, through the astriction?clearing of the lung and descending Qi?dispersing functions, moves the heart-fire downward. These functions are deeply related with changing seasons; thus, these functions can be explained with the ascending kidney-water and descending heart-yang of the five viscera.

• 제어로봇시스템학회논문지
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• 제14권11호
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• pp.1139-1145
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• 2008

A robust position sensing system is proposed in this paper for a ubiquitous mobile robot which moves indoors as well as outdoors. The Differential GPS (DGPS) which has a position estimation error of less than 5 m is a general solution when the mobile robot is moving outdoor, while an active beacon system (ABS) with embedded ultrasonic sensors is reliable as an indoor positioning system. The switching from the outdoor to indoor or vice versa causes unstable measurements on account of the reference coordinates and algorithm changes. To minimize the switching time in the position estimation and to stabilize the measurement, a robust position sensing system is proposed. In the system, to minimize the switching delay, the door positions are stored and updated in a database. Using the database, the approaching status of the mobile robot from indoor to outdoor or vice versa has been checked and the switching conditions are prepared before the mobile robot actually moves out or moves into the door. The reliability and accuracy of the robust positioning system based on DGPS and ABS are verified and demonstrated through the real experiments using a mobile robot prepared for this research.

• 환경영향평가
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• 제15권1호
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• pp.67-78
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• 2006

Global warming brings about changes of diverse environmental, especially changes of plant distribution. The purpose of this paper is to examine the relationship between temperature rise and changes of northern limit of vegetation growth in Korea. Bamboos (Phyllostachys) and boundary between the northern type and southern type of garlic (Allium sativum L.) were selected. The data of the distributions of bamboos and garlic are collected by field survey and interviews. Temperature is analyzed from 1904 to 2000. The northern limit of Phyllostachys moves 60-100 km northward, for about 100 years, the period of 1907-2003 and mean temperature of Korea increases about $2^{\circ}C$ during the same period. It means that the northern limit moves 30-50 km northward, for each $1^{\circ}C$ rising of January mean temperature. The boundary between the northern type and southern types of garlic moves northward 40-140 km from 1980s to 2000. The moving width is broad in the west coastal region while the width is narrow in the inland and mountain regions. The mean moving width is about 100 km.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권6호
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• pp.258-266
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• 2002

This paper proposes the methodology of the image processing algorithm that estimates the pose of the inner-pipe crawling robot. The inner-pipe crawling robot is usually equipped with a lighting device and a camera on its head for monitoring and inspection purpose of defects on the pipe wall and/or the maintenance operation. The proposed methodology is using these devices without introducing the extra sensors and is based on the fact that the position and the intensity of the reflected light from the inner wall of the pipe vary with the robot posture and the camera. The proposed algorithm is divided into two parts, estimating the translation and rotation angle of the camera, followed by the actual pose estimation of the robot . Based on the fact that the vanishing point of the reflected light moves into the opposite direction from the camera rotation, the camera rotation angle can be estimated. And, based on the fact that the most bright parts of the reflected light moves into the same direction with the camera translation, the camera position most bright parts of the reflected light moves into the same direction with the camera translation, the camera position can be obtained. To investigate the performance of the algorithm, the algorithm is applied to a sewage maintenance robot.

• Wind and Structures
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• 제21권3호
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• pp.289-309
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• 2015

Vertical profiles of mean and fluctuating wind velocities over water waves were studied, by performing Large-Eddy Simulations (LES) on a fully developed turbulent boundary layer over simplified water waves. The water waves were simplified to two-dimensional, periodic and non-evolving. Different wave steepness defined by $a/{\lambda}$ (a : wave amplitude; ${\lambda}$ : wavelength) and wave age defined by $c/U_b$ (c: phase velocity of the wave; $U_b$ : bulk velocity of the air) were considered, in order to elaborate the characteristics of mean and fluctuating wind profiles. Results shows that, compared to a static wave, a moving wave plays a lesser aerodynamic role as roughness as it moves downstream slower or a little faster than air, and plays more aerodynamic roles when it moves downstream much faster than air or moves in the opposite direction to air. The changes of gradient height, power law index, roughness length and friction velocity with wave age and wave amplitude are presented, which shed light on the wind characteristics over real sea surfaces for wind engineering applications.

• 동아시아경상학회지
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• 제8권1호
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• pp.1-19
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• 2020

Purpose - This study is to classify quality characteristics of online environment-friendly agricultural products shopping malls into 6 categories and to empirically test their relationship with customer trust, perceived manageability, perceived utility and purchase intention. Research design, data, and methodology - This study targeted adults who have purchased ecofriendly agricultural production online malls for 4 weeks from September 3 to September 30, 2019. The survey type used was a structuralized self-report survey questionnaire made to meet the research purpose in 2019 as the time range. Out of 800 questionnaires, 500 copies are used after excluding surveys with insincere responses. Results - First, results to hypothesis 1, which was about independent variables and customer trust. Analysis showed that health, familiarity, platform reputation, reviews and product quality were found to have significant effect on customer trust; the hypothesis was adopted. On the other hand, system security did not affect customer trust significantly; it was rejected. Second, customer trust was shown to have significant effect on perceived manageability and perceived utility, so the hypothesis was adopted. Third, the hypothesis that perceived manageability moves onto perceived utility was adopted. Moreover, the hypothesis that perceived manageability moves onto purchase intention and the hypothesis that perceived utility moves onto purchase intention were adopted as well. Conclusions - Furthermore, the results of the study imply that it's imperative for online environment-friendly agricultural products shopping malls to consider their characteristics as the means to increase purchase intention of customers.

• 한국환경과학회지
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• 제21권3호
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• pp.327-337
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• 2012

Air pollution inventories are aggregated around south-eastern part of the Korean Peninsular including Busan, Ulsan, and Changwon cities. Because densely populated cities are concentrated in this region, air pollutants emitted from one of these cities tend to be impacted on the air quality of other cities. In order to clarify the seasonal movement pattern of emitted particles, several numerical simulations using WRF/FLEXPART were carried out. Four cases were selected for each season. The Weather Research and Forecasting model (WRF) reproduced atmospheric flow fields with nested grids. The seasonal pattern of air mass of study area was determined by backward and forward trajectories. As a result, the air parcel moves from northwest to southeast due to northwesterly winds in spring and winter. Also air parcel transports from south to north in summer, and moves from west to east. Because the air mass moves differently in each season, these characteristics should be considered when performing air quality analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권4호
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• pp.843-859
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• 2024

The university course scheduling problem (UCSP) aims at optimally arranging courses to corresponding rooms, faculties, students, and timeslots with constraints. Previously, the university staff solved this thorny problem by hand, which is very time-consuming and makes it easy to fall into chaos. Even some meta-heuristic algorithms are proposed to solve UCSP automatically, while most only utilize one single algorithm, so the scheduling results still need improvement. Besides, they lack an in-depth analysis of the inner algorithms. Therefore, this paper presents a novel and practical approach based on Tabu search and simulated annealing algorithms for solving USCP. Firstly, the initial solution of the UCSP instance is generated by one construction heuristic algorithm, the first fit algorithm. Secondly, we defined one union move selector to control the moves and provide diverse solutions from initial solutions, consisting of two changing move selectors. Thirdly, Tabu search and simulated annealing (SA) are combined to filter out unacceptable moves in a parallel mode. Then, the acceptable moves are selected by one adaptive decision algorithm, which is used as the next step to construct the final solving path. Benefits from the excellent design of the union move selector, parallel tabu search and SA, and adaptive decision algorithm, the proposed method could effectively solve UCSP since it fully uses Tabu and SA. We designed and tested the proposed algorithm in one real-world (PKNU-UCSP) and ten random UCSP instances. The experimental results confirmed its effectiveness. Besides, the in-depth analysis confirmed each component's effectiveness for solving UCSP.