• Ceramist
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• v.20 no.4
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• pp.55-73
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• 2017

As one of the most versatile semiconductors, zinc oxide (ZnO) with one-dimensional (1-D) nanostructures has been significantly developed for the application of ultraviolet (UV) lasers, photochemical sensors, photocatalysts, and so on. Such 1-D nanowires could be easily achieved due to the anisotropic growth rate along the [0001] direction. However, such typical growth habit leads to decrease the surface area of the (0001) plane, which plays a central role in not only UV lasing action but also photocatalytic reaction. This fact lead us to develop ZnO crystal with enhanced polar surface area through crystal growth control. The purpose of this review is to provide readers a simple route to plate-type ZnO crystal with highly enhanced polar surfaces and their applications for UV-laser, photocatalyst, and antibacterial agents. In addition, we will highlight the recent study on pilot-scale synthesis of plate-type ZnO crystal for industrial applications.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.2056-2062
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• 2009

Recent advances in computer technology have brought more dependence on software to train control systems. Hence, the safety assurance of the vital software running on the railway system is very critical task and yet, not many works have been done. While much efforts have been reported to improve electronic hardware's safety, not so much systematic approaches to evaluate software's safety, especially for the vital software running on board train controllers. In this paper, we have developed the static software testing tool for railway signaling, especially Fagan Inspection supporting tool. This static testing tool for railway signaling can be utilized at the assessment phase, and also usefully at the software development stage also. It is anticipated that it will be greatly helpful for the evaluation on the software for railway signalling system.

• 연구논문집
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• s.33
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• pp.17-25
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• 2003

In this work, thermal design of a PCR chip for LOC is systematically conducted. From the numerical simulation of a PCR chip based on the finite volume method, how to control the average temperature of a PCR chip and the temperature difference between the denaturation zone and the annealing zone is presented. The average temperature is shown to be controlled by adjusting heat input and a cooler as well as a heater is shown to be necessary to obtain three individual temperature zones for polymerase chain reaction. To reduce the time required, a heat sink for the cooler is not included in the calculation domain for the PCR chip and heat sink design is conducted separately by using a compact modeling method, the porous medium approach.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3031-3033
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• 2000

Surveillance system on the internet has attained lots of interests recently. Computer gives surveillance system various functions like remote control and motion detecting. In this paper. auto target tracking system using Pan/Tilt camera is suggested. It consists of UNIX server and Pan/Tilt camera. When UNIX server detect motions from images it sends Pan/Tilt command to camera and camera moves by command. After finishing movement camera replies to server and server starts detecting motion again. To improve performance of motion detecting and tracking images are divided into 9 sub-regions and camera behaves differently. It is certain that robust tracking is achieved when sub-region is applied.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.2
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• pp.435-440
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• 2011

A touchless user interface system is proposed for real-time mobile devices in this work. The proposed system first recognizes the position of pattern to interact various applications based on the scene taken from mobile camera. Then, the proposed system traces the route of the pattern, which estimates the motion of pattern based on the mean-shift method. Based on this information, we control menu and keypad for the various applications. Differ from other user interface systems, the proposed system provides the new experience to even for the user of low-end mobile without additional hardware. Simulation results demonstrate that the proposed algorithm provides better interaction performances than the conventional method, while achieving real-time user interacting for mobile devices.

• Journal of the Institute of Convergence Signal Processing
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• v.1 no.2
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• pp.122-130
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• 2000

This paper mainly deals with the modified version of conventional PRMA(Packet Reservation Multiple Access). In the existing PRMA schemes, the occupied slot in the initial access state is not allowed to be reserved in the silent period and retrial of gaining the slot access has to pay additional packet dropping. Whereas in the modified model, we propose to utilize a control minislot that maintains slot reservation and this prevents additional packet drop occurrence since initial access, and this slightly improves the system performance.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1120-1122
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• 2005

인터넷의 급속한 보급으로 인해 데이터 전송 시 발생하는 공간상의 제약을 쉽게 극복 할 수 있게 되어 전 세계 어디서든지 데이터를 주고받을 수 있게 되었다. 이러한 인터넷 웹기반의 장점을 살려서 그동안 실험 연구용으로 사용하던 서보시스템의 PID 제어방법을 인터넷을 기반으로 한 원격제어 시스템으로 구현하였다. 본 논문에서는 DC 서보 모터와 모터 제어 보드, NI사의 DAQ, PC로 시스템을 구현 하였다. UI(User Interface)는 LabVIEW 프로그램을 이용하여 GUI(Graphical User Interface)로 DC 서보 모터의 제어와 작동상태의 모니터링이 용이하도록 하였고, 최적의 PID 이득값을 설정하여 원하는 속도 응답 특성이 양호한 제어를 할 수 있게 하였다. 더 나아가 PID 제어 방법을 원격 실시간의 가상 실습이 가능한 e-Learning에 적용 할 수 있음을 확인하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.754-763
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• 2002

Direct drive servovalve(DDV) is a kind of one-stage valve since the rotary motion of DC motor is directly transferred to the linear motion of valve spool through the link. Since the structure of DDV is simple, it is less expensive, more reliable and offers reduced internal leakage and reduced sensitivity to fluid contamination. However, the flow force effect on the spool motion is significant such that it induces large steady-state error in a step response. If the proportional control gain is increased to reduce the steady-state error, the system becomes unstable. In order to satisfy the system design requirements, the classical controller is designed using the analytical Bode method.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.167-168
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• 2015

본 논문에서는 전기자동차 충전용 자기유도방식 무선전력전송 (IPT) 시스템에서 zero current switching (ZCS) 동작으로 인한 스위치 손상을 방지하는 제어 알고리즘을 제안한다. 알고리즘을 제안하기 위해 IPT 시스템에서 공진전류 위상 변화를 일으키는 bifurcation 현상과 금속성 이물질의 영향에 대해 분석하고, 분석 결과를 고려하여 동작 주파수 제어 알고리즘을 제안한다. 제안한 알고리즘은 시스템을 zero voltage switching (ZVS) 영역에서 동작하게 하고 일정한 출력 전압을 얻도록 제어한다. 제안한 알고리즘의 타당성을 PSIM 시뮬레이션을 통해 검증한다.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.261-262
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• 2010

This paper presents the design, development and performance of a power conditioning system (PCS) for application to a Molten Carbonate Fuel Cell (MCFC) for high power generation system. The controller must also supervise the total PCS operation while communicating with the fuel cell system controller. A control method for parallel operation of 250kW PCS was implemented and verified respectively. Experimental performances are compared to minimum target requirements of the PCS for MCFC respectively.