• 제어로봇시스템학회논문지
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• 제15권2호
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• pp.148-154
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• 2009

In this paper, an embedded Kalman filter for a time-delayed controller is designed on an FPGA to estimate accelerations of the robot arm. When the time-delayed controller is used as a controller, the inertia estimation along with accelerations is needed to form the control law. Although the time-delayed controller is known to be robust to cancel out uncertainties in the nonlinear systems, performances are very much dependent upon estimating the acceleration term ${\ddot{q}}(t-{\lambda})$ along with inertia estimation ${\hat{D}}(t-{\lambda})$. Estimating accelerations using the finite difference method is quite simple, but the accuracy of estimation is poor specially when the robot moves slowly. To estimate accelerations more accurately, various filters such as the least square fit filter and the Kalman filter are introduced and implemented on an FPGA chip. Experimental studies of following the desired trajectory are conducted to show the performance of the controller. Performances of different filters are investigated experimentally and compared.

• 대한기계학회논문집
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• 제12권6호
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• pp.1415-1427
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• 1988

본 연구에서는 막냉각되고 있는 수평평판에서 분사각도와 분사율의 변화가 열 전달계수에 미치는 영향을 주 연구대상으로 하였다. 열전달계수의 측정을 위하여 나 프탈렌 승화법을 이용하였고, 열전달 계수에 가장 큰 영향을 미치는 유동장에 대한 이 해를 위해 슐리렌 광학계를 이용한 유동의 가시화 실험을 수행하였다. 분사각도는 Fig.1에서와 같이 y축 방향으로의 수직분사(case 1), 유동방향(x축방향)dp eogo 35˚ 경사진 분사(case 2), 그리고 유동의 직각방향(Z축)dp eogo 35˚경사진 분사(case 3) 등 3가지의 경우에 대해 실험하였고, 분사율은 0.5, 1.0, 1.8로 변화시켰다.

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.29-35
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• 2016

It is important to uniformly supply the fuel gas into the reaction activity area in polymer electrolyte membrane fuel cell (PEMFC). Recent studies have shown that the cell performance can be significantly improved by employing metal foam gas distributor as compared with the conventional bipolar plate types. The metal foam gas distributor has been reported to be more efficient to fuel transport. In this study, three-dimensional computational fluid dynamics (CFD) simulations have been performed to examine the effects of metal foam flow field design on the fuel supply to the reaction site. Darcy's law is used for the flow in the porous media. By solving additional advection equation for fluid particle trajectory, the gas transport has been visualized and examined for various geometrical configuration of metal foam gas distributor.

• 전기학회논문지
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• 제61권7호
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• pp.1032-1040
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• 2012

This paper proposes controller of leader robot considering following robot with input constraints based on leader-following approach. In the previous formation control researches, it was assumed that leader and follower is same object. If leader robot drives as maximum speed that the initial position errors still remain even if following robot have same velocity as a leader. In the situation that velocity of following robot is lower than its leader robot, following robot cannot follow leader robot. Furthermore, the following robot will not be able to made formation with leader robot and keep proximity communication or sensing range. Therefore, multiple mobile robot system using leader-following method should be guaranteed range to get information each other. In this paper, Leader robot is driving to goal position using linear controller and following robot is following trajectory to be made from leader robot. We assume that following robot has input constraints to realize different performance between leader robot and following robot. We design controller of leader robot for desired goal position including the errors between formation and following robot. Thus, we propose leader robot controller considering input constraints of following robot. Finally, we were able to confirm the validity of the proposed method based on simulation results.

• 동력기계공학회지
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• 제15권5호
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• pp.91-96
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• 2011

The handling ability of containers at the terminal strongly depends on the performance of the cargo handling system such as RTGC(Rubber Tired Gantry Crane) and RMGC(Rail Mounted Gantry Crane). This paper introduces a guide line measurement system on the operating condition, in which two camera are installed to detect the guide line. Because the line tracking is the basic technique for control system design of RTGC, it is necessary to develop a useful and reliable measurement system. If the displacement and angle of the RTGC relative to a guide line as the trajectory to follow is obtained, the position of RTGC is automatically calculated. Therefore, in this paper, a camera-based measurement system is introduced. The proposed measurement system is robust against light fluctuation and cracks of the guide line. This system consists of two camera and a PC which are installed at the lower side of the RTGC. Two edges of the guide line are detected from an input image taken by the cameras in the moving state, and these positions are determined in a Hough parameter space by using the Hough transformation method. From the experimental results, the accuracy and usefulness of the proposed system is evaluated by comparing other instruments.

• 제어로봇시스템학회논문지
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• 제11권2호
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• pp.160-166
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• 2005

In this paper, to overcome drawbacks of FLC a self tuning fuzzy sliding mode controller is proposed, which controls the position of excavator's attachment, which can be regarded as an ill-defined system. It is reported that fuzzy logic theory is especially useful in the control of ill-defined system. It is important in the design of a FLC to derive control rules in which the system's dynamic characteristics are taken into account. Control rules are usually established using trial and error methods. However, in the case where the dynamic characteristics vary with operating conditions, as in the operation of excavator attachment, it is difficult to find out control rules in which all the working condition parameters are considered. Experiments are carried out on a test bed which is built around a commercial Hyundai HX-60W hydraulic excavator. The experimental results show that both alleviation of chattering and performance are achieved. Fuzzy rules are easily obtained by using the proposed method and good performance in the following the desired trajectory is achieved. In summary, the proposed controller is very effective control method for the position control of the excavator's attachment.

• 유통과학연구
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• 제19권10호
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• pp.75-86
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• 2021

Purpose: The purpose of this study is to address policy preparation and amendments on regulations in accommodation sharing for resource distribution by fostering better adjustment in a society, since previous studies are rarely investigated in those issues. After conduct exploratory research about laws and regulations of accommodation sharing, this study investigates how effective policy instruments improve trust in accommodation sharing and potential growth by investigating the perceptions of individuals and by applying policymaking procedures. Research design, data and methodology: The data is collected via online survey. Structural equation modeling with confirmatory factor analysis and non-recursive model with multiple regression analysis were applied. Results: The results of this study found that among proposed policy instruments, individuals perceive local ordinances, government publicizing and campaign, trust marks, taxation, penalties, and government controls are effective to build trust in accommodation sharing. Policies geared toward the majority of the public are more effective, while governments should establish a strategic approach as to which policies are introduced in public and which role the government plays in the departments. Conclusions: The results provide policy and managerial implications how to enhance distributional values of accommodation sharing economy with proper preparations and amendments of laws and regulations.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.785-788
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• 2009

비행자료 처리시스템은 항공기 관제를 위한 모든 비행관련 자료를 처리하고 관리하며 항적 모델링을 하기 위한 시스템으로 항공관제용 통합 정보처리 시스템의 핵심 기능을 수행하는 역할을 담당한다. 항공기의 안전한 운항을 위해서는 비행자료 처리를 통해 항공교통관제기관간의 정보전달과 교환은 필수적인 요소이다. 따라서 본 논문에서는 비행자료 처리시스템의 개발을 위해 기능을 분석하고, 설계 시 필요한 고려사항을 살펴보고자 한다.

• 한국해양공학회지
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• 제35권1호
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• pp.13-23
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• 2021

Since the introduction of the mandatory energy efficiency design index (EEDI), several studies have been conducted on the maneuverability of waves owing to the decrease in engine power. However, most studies have used the mean wave force during a single cycle to evaluate maneuverability and investigated the turning performance. In this study, we calculated the external force in accordance with the angle of incidence of the wave width and wavelengths encountered by KVLCC2 (KRISO very large crude-oil carrier) operating at low speeds in regular waves using computational fluid dynamics (CFD). We compare the model test results with those published in other papers. Based on the external force calculated using CFD, an external force that varies according to the phase of the wave that meets the hull was derived, and based on the derived external force and MMG control simulation, a maneuvering simulation model was constructed. Using this method, a weather vaning simulation was performed in regular waves to evaluate the course-keeping ability of KVLCC2 in waves. The results confirmed that there was a difference in the operating trajectory according to the wavelength and phase of the waves encountered.

• 대한건축학회논문집:계획계
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• 제35권1호
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• pp.107-115
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• 2019

This research explores a historical trajectory of the Milwaukee Art Museum from its establishment to the third expansion over the last six decades. After established in 1957 by the architect, Eero Saarinen, this museum underwent three expansions led by three different architects including, David Kahler, Santiago Calatrava, and James Shields. Reasons for expanding the museum were varied. A lack of exhibition space, an absence of visual identity, and path interruption problem within urban contexts were the main factors of a series of expansion. Furthermore, this research points out that there are three issues in the process of the expansion. The first is connection issues between the downtown and the lakefront in which the museum has blocked the public flow. The second, there were controversies on the allocation of the expanded space among the main body of the decision including architects, curators, and stakeholders. The last one is relationships among architects. This is related to each architect's attitude toward the museum. Drawing on historical documents and interviews with the regional architects, I argue that the identity and values of the museum have changed over time through the expansions rather than having the invariable.