• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.173-181
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• 2016

This paper reports on the development of a roller-cam clutch mechanism. This mechanism can transfer bidirectional torque with high backdrivability, as well as increase actuation energy efficiency, in electrical exoskeleton robots. The developed mechanism was installed at the robot knee joint and unclutched during the swing phase which uses less metabolic energy, thereby functioning as a passive joint. The roller-cam clutch aimed to increase actuation energy efficiency while also producing high backdrivability by generating zero impedance for users during the swing phase. To develop the mechanism, mathematical modeling of the roller-cam clutch was conducted, with the design having more than three safety factors following optimization. Titanium (Ti-6AL-4V) material was used. Finally, modeling verification was done using ANSYS software.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.765-767
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• 2016

Building Energy commissioning is a process in which verifying and making the document during entire lifetime including planning, design, construction, test run of equipment, and maintenance to minimize the operational problems of building energy efficiency. The general commissioning is replacing the equipment or reconstructing the skin to achieve the performance for the design. This process is expensive and has the disadvantage of taking a long payback period by one operation. In this paper, we studied the monitoring-based commissioning (MBCx) to increase the energy efficiency of buildings through analyzing energy use data. MBCx is modeling a building energy, comparing the real energy use with it, detecting the cause of falling the efficiency, and running the optimal operation regularly.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.3
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• pp.277-285
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• 2010

We examined the optimal shape of blades and efficiency of a self-power generator when the self-power generator using flow of the water in pipe as the power source was installed. Selected factors were the shape of blades, the number of blades, pitch angle, and the existence of separator. GAMBIT2.4 was used as a modeling program, FLUENT6.3, which is computational fluid dynamics simulation program, was used as an analytical model. In the case of a viscous model, k-epsilon standard model was chosen. As a result, when the number of blades was increased, the efficiency and maximum moment were enhanced slightly. The pitch of blades went up, and maximum moment was also increased. The optimal pitch of blade was 62.5 degree and the efficiency was increased by 30%. The efficiency was also increased when a separator was installed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.4
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• pp.283-291
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• 2021

The Korean stow net is a fishing method that utilizes the changing direction of the net entrance with the tidal current. This study attempted to obtain basic data from the recent offshore stow net fisheries to improve the gear by analyzing the dynamic behavior of the nets affected by current speed and direction using computer simulations. A numerical calculation was performed at a current speed of 0.5 knot between 2.5 knot at each 0.5 knot. The time taken for the gear opening was the longest from 0.5 knot at 1,500 seconds and the shortest from 2.5 knot at 450 seconds in the simulations. In all cases, the net width and tension at net deployment gradually decreased as the current speed decreased. However, the net height tended to increase inversely proportional to the current speed. During the net rotation, the net height was maintained at all cases. The net width and tension fluctuated, but the regularity was very low. In this study, the calculated simulation data showed that the opening efficiency decreased proportional to the current speed. The opening efficiency is related to the catching efficiency; therefore, it is necessary to improve the gear to enhance its opening efficiency.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1449-1454
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• 2003

For many industrial processes there are good static models used for process design and steady state operation. By using system identification techniques, it is possible to obtain black-box models with reasonable complexity that describe the system well in specific operating conditions [1]. But black-box models using inductive modeling(IM) is not suitable for model based control because they are only valid for specific operating conditions. Thus we need to use deductive modeling(DM) for a wide operating range. Furthermore, deductive modeling is several merits: First, the model is possible to be modularized. Second, we can increase and decrease the model complexity. Finally, we are able to use model for plant design. Power plant must be able to operate well at dramatic load change and consider safety and efficiency. This paper proposes a simplified nonlinear model of an industrial boiler, one of component parts of a power plant, by DM method and applies optimal control to the model.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.11a
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• pp.54-57
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• 2006

The digital modeling process is visualization of designer's specific intension in digital virtual space by constructing computer and information system that fits the designer's intension and morphological characteristic of the space that to be modeled. Digital Modeling Process has been brought to attention for it's design efficiency and potentialities as new creative tool. The effect of DMP, in spacial design process has been grown from simply providing a ways to visualize designer's idea toward utilizing modeling data for real construction which includes architectural and constructional material. The purpose of this study is to find optimal methodological answers to spatial design process that is improved and specialized due to rapid improvement of digital media.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.8 s.239
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• pp.1153-1160
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• 2005

Many methods of spot weld modeling have been developed to increase efficiency and guarantee the robustness fer the CAE analysis. In this research they are introduced and the performance is compared in a viewpoint of stiffness and durability. For evaluating the performance a multi-spot welded specimen as well as two single welded specimen is used. The results show that the CWELD element considering 'patch to patch' is stiffer than other modeling methods in stiffness and more conservative in durability. It also offers simple modeling and since it is much easier to maintain the orrhogonality of the BAR element expressing a nugget, we can obtain more exact reaction forces and moments in a nugget. Therefore the CWELD element is the most excellent in the assessment of durability.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.06a
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• pp.445-454
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• 2001

A workflow model is useful fur business process analysis and has often been implemented for office automation through information technology. Accordingly, the results of workflow modeling need to be systematically managed as information assets. In order to manage the modeling process effectively, it is necessary to enhance the efficiency of their reuse. Therefore, this paper creates a Document-barred Workflow Modeling Support System (DWMSS) using a case-based reasoning (CBR) approach. It proposes a system architecture, and the corresponding modeling process is developed. Furthermore, a repository, which consists of a case base and vocabulary base, is built. A carte study is illustrated to demonstrate the usefulness of th is system.

• The Journal of Society for e-Business Studies
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• v.13 no.4
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• pp.93-110
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• 2008

Reference modeling for Collaborative Networked Organizations(CNOs) has just started, and Enterprise Architecture Modeling Languages(EAMLs) for CNOs are very few. Lack of reference models makes it difficult for people to communicate with each other and lack of EAMLs also makes it difficult to implement information systems for CNOs. We propose an EAML for CNO called CAML. It supports (1) multi-level modeling based on Model- Driven Architecture of OMG's for expressive power and efficiency of implementations, and (2) multi-focus modeling based on Zachman Framework for completeness of modeling The effectiveness of the CAML is investigated through modeling of a supply chain and execution of change impact analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.70-77
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• 1996

Recently many efforts have been made to improve the efficiency of design and production of the structures using the automation system. But, this work has been progressed as independent or partial system. And, the study on the integrated system is not sufficient in application for practical problems yet. This paper deals with the fundamental concept of modeling system and application method on structural modeling. At first, the core of the integrated system is a shape modeling system that can represent the geometric and topological information. This system must be designed as an open system to be combined with each independent automation system. The appropriate concept to realize this system on structural modeling is object oriented modeling and this enables to integrate each automation system successfully, This concept was applied to automatic mesh generation. For shape modeling system, half-edge data structure that is being used in solid modeling was modified to handle the plate structure in the plane. And, to generate the triangular meshes, direct node connection method was used. And, as a result, the integrated system that generate the meshes of two dimensional structure automatically was realized. And, programmed by C++, these systems can be combined with other systems easily and have good reusability.