• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권3호
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• pp.139-146
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• 2003

In this paper, the steady-state operating performance analysis for the three-phase squirrel cage rotor self-excited induction generator (SEIG) driven by a variable-speed prime mover (VSPM) in addition to a constant-speed prime mover (CSPM) is presented on the basis of an effective algorithm based on its frequency-domain equivalent circuit. The operating characteristics of the three-phase SEIG coupled by a VSPM and/or a CSPM are evaluated on line processing under the condition of the electrical passive load parameters variations with simple and efficient computation processing procedure in unregulated voltage control loop scheme. A three-phase SEIG prototype setup with a VSPM as well as a CSPM is implemented for the small-scale clean renewable and alternative energy utilizations. The experimental operating characteristic results are illustrated and give good agreements with the simulation ones.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.30.1-30
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• 2001

This paper describes a new cooperative strategy for two wheelchairs to climb a step. These two wheelchairrobots are connected with a simple linkage mechanism between the rear of one wheelchair and the front of another. Two wheelchair robots climb a step one after the other. In this research, We did not use a method by Which a robot lifts up and supports its weight using any special actuator but a method of handling the robot's moment of rotation by the force of the link which come from the assisting robot. This method is especially influenced by the height of the two robot's link positions. So we study this method from the viewpoint of changing the two-link positions....

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.30.5-30
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• 2001

This paper describes a new design of blimp having wheeled vehicle part. This system can work both on the ground using wheeled vehicle and in the air using the floating capability of the blimp part. The passive wheeled mechanism in the vehicle part enables the stable taking off, landing on as well as it is greatly helpful to keep a stationary position on the floor. On the other hand, the floating capability enables the wheeled blimp to fly freely regardless of the ground condition or obstacles. The wheeled blimp can be used as an agent robot for the tole-presence application. Using multimedia devices such as camera, speaker, LCD and microphone mounted on the blimp surface, this system can get necessary information at the local site and communicate with person from a distance. As a typical tele-presence application, the wheeled blimp is currently being developed to a tole-guidance robot working in public indoor areas such 35 exhibition halls, departments, hospitals, etc ...

• Steel and Composite Structures
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• 제48권3호
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• pp.353-365
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• 2023

Shape memory alloys (SMAs) have emerged as a novel functional material that is being increasingly applied in diverse fields including medical, aeronautical and structural engineering to be used in the active, passive and semi-active structural control devices. This paper is mainly aimed at evaluating the ductility and response modification factor of the steel plate shear wall (SPSW) frames with and without the Ni-Ti shape memory alloys. To this end, different configurations were utilized, in which the walls were used in the first, third, middle, and all stories. The models were numerically analyzed using OpenSees Software. The obtained results indicate that improving the shape memory properties of alloys can greatly enhance the ductility and response modification factor. Furthermore, the model whose first and third stories are equipped with the SMA shear wall was found to be 290% more ductile, with a greater response modification factor compared to the unequipped frame.

• Architectural research
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• 제19권2호
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• pp.45-52
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• 2017

Recently, as a new perspective to view the architecture in relation to global environmental problems, interest in environmental architecture that conforms to the surrounding environment and nature with nature has been expanded as a part of the natural ecosystem, rather than seeing the building as an independent entity. Traditional Korean architecture creates a comfortable indoor environment by appropriately using the natural energy around, ranging from the arrangement of the building and the space composition to the use of detailed materials and to harmonize the artificial architectural environment without harming the natural ecosystem. The purpose of this study is to propose a method to apply the environmental control techniques of traditional buildings to modern buildings. As a research method, the characteristics of Korean traditional buildings according to the climatic characteristics of Korea were recognized through existing literature data and when applied to methods of traditional buildings, ventilation systems, control through eaves, and humidity control using Hanji the effect of energy load control on traditional buildings was analyzed and identified through existing literature. After analyzing the problems of modern architecture, we analyzed the effect of the environmental control system of traditional architecture on modern architecture. Simulation results show that the application of the environmental control system of traditional buildings to modern buildings reduces the cooling and heating load of modern buildings and has an effect on humidity control. This study suggests that quantitative energy saving will be possible if the environmental control techniques of traditional buildings are appropriately applied to modern buildings.

• 한국멀티미디어학회논문지
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• 제4권5호
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• pp.377-389
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• 2001

최근의 웹 환경 확산으로 웹을 기반으로 하는 워크플로우 시스템의 구축경향이 높다. 워크플로우 시스템에서 중요한 기능은 미리 정의된 규칙, 절차 및 조건에 따라 작업흐름을 자동화하는 것으로 정보흐름에 있어서 수동적인 작업을 배제하고 GUI 방식을 지원하며 정보처리의 이동성이 고려되어야 한다. 특히 분산된 업무조직의 작업흐름을 위한 분산워크플로우 시스템은 웹 환경에 있어서 프로세스 로직에 따른 태스크간의 이동제어와 결함허용 및 실시간적 처리가 가능해야 한다. 그러나 기존의 메일 시스템은 전송위주로서 작업흐름을 자동화하려는 경우에 적합하지 못하다. 이러한 문제를 해결하기 위하여 작업흐름 설계가 가능하고 작업흐름제어를 자동화 할 수 있는 분산워크플로우 엔진이 필요하다. 본 논문에서는 웹 메일을 이용하여 작업흐름을 그래픽 인터페이스로 작성하고 이를 절차적 수행이 가능한 스크립트 코드를 생성하는 브라우저를 작성하였으며, 분산환경에서 태스크 처리를 위한 프로세스 스케쥴러 및 서버노드의 결함 발생시 이를 허용하는 전처리기를 지닌 프로세스 엔진을 설계하였다. 이 이스템은 서버의 결함이나 사용자의 부재시 처리를 대행하므로 시스템의 신뢰성과 가용성을 향상시키고, 데이터베이스 기반 워크플로우 시스템보다 비용을 감소시킨다.

• Progress in Superconductivity
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• 제10권1호
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• pp.60-67
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• 2008

We present domestic efforts for superconducting fault current limiter (SFCL) application in the Korea Electric Power Corporation (KEPCO) grid and pending points at issue. KEPCO's decision to upgrade the 154 kV/22.9 kV main transformer from 60 MVA to 100 MVA cast a problem of high fault current in the 22.9 kV distribution lines. The grid planners supported adopting an SFCL to control the fault current. This environment friendly to SFCL application must be highly dependent upon the successful development of SFCL having specifications that domestic utility required. The required conditions are (1) small size of not greater than twice of 22.9 kV gas insulated switch-gear (GIS), (2) sustainability of current limitation without the line breaking by circuit breakers (CB) for maximum 1.5 seconds. Also, optionally, recommended is (3) the reclosing capability. Conventional resistive SFCLs do not meet (1) $\sim$ (3) all together. A hybrid SFCL is an excellent solution to meet the conditions. The hybrid SFCL consists of HTS SFCL components for fault detection and line commutation, a fast switch (FS) to break the primary path, and a limiter. This characteristic structure not only enables excellent current limiting performances and the reclosing capability, but also allows drastic reduction of HTS volume and small size of the cryostat, resulting in economic feasibility and compactness of the equipment. External current limiter also enables long term limitation since it is far less sensitive to heat generation than HTS. Semi-active operation is another advantage of the hybrid structure. We will discuss more pending points at issues such as maintenance-free long term operation, small size to accommodate the in-house substation, passive and active control, back-up plans, diagnosis, and so on.

• 제어로봇시스템학회논문지
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• 제18권7호
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• pp.650-657
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• 2012

An effective dual-mode camera system(a passive wide-angle camera and a pan-tilt-zoom camera) is proposed in order to improve the performance of visual surveillance. The fixed wide-angle camera is used to monitor large open areas, but the moving objects on the images are too small to view in detail. And, the PTZ camera is capable of increasing the monitoring area and enhancing the image quality by tracking and zooming in on a specific moving target. However, its FOV (Field of View) is limited when zooming in on a specific target. Therefore, the cooperation of wide-angle and PTZ cameras is complementary. In this paper, we propose an automatic initial set-up algorithm and coordinate transform method from the wide-angle camera coordinate to the PTZ one, which are necessary to achieve the cooperation. The automatic initial set-up algorithm is able to synchronize the views of two cameras. When a moving object appears on the image plane of a wide-angle camera after the initial set-up positioning, the obtained values of the wide-angle camera should be transformed to the PTZ values based on the coordinate transform method. We also develope the PTZ control method. Various in-door and out-door experiments show that the proposed dual-camera system is feasible for the effective visual surveillance.

• 전력전자학회논문지
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• 제18권4호
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• pp.403-411
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• 2013

This paper proposes an isolated bidirectional three-phase push-pull dc-dc converter for high power application such as eco-friendly vehicles, renewable energy systems, energy storage systems, and solid-state transformers. The proposed converter achieves ZVS turn-on of all switches and volume of passive components is small by an effect of three-phase interleaving. The proposed converter has identical switching pattern for both boost and buck mode, and therefore can provide seamless characteristic at the mode transition. A 3kW prototype of the proposed converter has been built and tested to verify the validity of the proposed operation.

• 한국통신학회논문지
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• 제8권3호
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• pp.96-104
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• 1983

동축 케이블이나 케이블 쌍을 사용하는 유선전송 시스템에 있어서 케이블의 전송특성에 의한 손실은 케이블 길이와 주위온도에 따라 변화하며 항상 $\sqrt f$ 특성 형태를 취한다. 이러한 형태의 손실을 보상하기 위해 궤환과 순방향 공급 경로의 직렬결함을 이용한 자동조절 능동가변 등화기를 제시하였다. 본 논문에 제시한 자동조절 능동가변 등화기는 종래의 수동가변 등화기가 가지고 있던 인덕터의 필요성, 복잡한 설계과정, 그리고 매우 복잡한 현대 전자제어 시스템과의 비 양립성 등 대부분의 결점을 제거시켜 준다. 또한 이러한 설계는 다른 능동가변 등화기 설계에 비해 많은 이점을 가지고 있으며 특시 1MHz이하에서의 정확한 등화에 응용할 수 있다.