• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1337-1345
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• 2011

In pressurized water reactors (PWRs), the reactor pressure vessel (RPV) upper head contains numerous control rod drive mechanism (CRDM) nozzles. In the last 10 years, the incidences of cracking in alloy 600 CRDM nozzles and their associated welds has increased significantly. Several axial and circumferential cracks have been found in CRDM nozzles in European PWRs and U.S. nuclear power plants. These cracks are caused by primary water stress corrosion cracking (PWSCC) and have been shown to be driven by welding residual stresses and operational stresses in the weld region. Therefore, detailed finite-element (FE) simulations for the Korea Nuclear Reactor Pressure Vessel have been conducted in order to predict the magnitudes of the weld residual stresses in the tube materials. In particular, the weld residual stress results are compared in terms for nozzle location, geometry factor$r_o$/t, geometry of fillet, and adjacent nozzle.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.6
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• pp.538-545
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• 2001

In this paper a gearless drive system using a permanent-maget synchronous motor for high speed elevators is addressed. The application of permanent magnet synchronous motor to an elevator traction machine enables several improvements including higher efficiency better ride comfort smaller size and lighter weight and so on A PWM boost converter has been also adopted so that DC-link voltage regulation bi-directional power flow and controllable power factor with reduced input current harmonics are possible. To increase the reliability and performance of overall control system the unified control board which can include the car and group controller as well as PWN converter/inverter controller has been designed based on a DSP TMS320VV33. In addition the dynamic load simulator system has been developed so that the drive system of high speed elevator can be tested and evaluated without and limitation on ride distance. Some experimental results are given to verify the effectiveness of the developed system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.203-211
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• 2015

The implanted telemetry system provides the monitoring of species while they move within their cages. Species monitored include mice, rats, rabbits, dogs, pigs, primates, sheep, horses, cattle, and others. A miniature transmitter implanted in each animal measures one or more parameters. Parameters measured include arterial pressure, intra-pleural pressure, left ventricular pressure, intra-ocular pressure, bladder pressure, ECG, EMG, EEG, EOG, temperature, activity, and other parameters and transmits the data via radio frequency signals to a nearby receiver. Every conventional dedicated transmitter contains one or more sensors, cpu and battery. Due to the expected life of battery, the measuring time is limited. To overcome these problems, electromagnetic inductive coupling based wireless power transmission technology using multiple transmit coils were proposed. Each coil having different active area are driven by the coil driver. In this research, parallel resonance based coil driver was proposed. In addition, the device to detect where the receiver is positioned was proposed. From the experiments we show how to determine the driving condition of coil driver.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.51-51
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• 2008

최근 센서, 전자기술의 발달은 소형 센서 기기의 구동에 필요한 파워를 줄여 주변의 진동이나 온도차등에서의 작은 에너지로도 센서 등의 소형 전자기기의 구동을 가능하게 했다. 이에 따라 전자기기의 구동에너지로써 에너지 하베스팅이 많은 관심을 받고 있다. 압전 효과를 이용하여 주변의 진동에너지를 전기에너지로 변화 시키는 압전에너지 하베스터는 온도차이나 태양광, 바람등과는 달리 날씨나 구동조건에 큰 영항을 받지 않는 장점과 그 크기가 비교적 소형이라는 장점이 있어 많은 연구가 진행되고 있다. 에너지 하베스터에서 생산된 에너지를 사용하기 위해서는 생산된 에너지를 저장장치에 저장해야 한다. 저장장치에 저장하기 위해서는 일정 이상의 전압과 많은 양의 전류가 있는 것이 효과적이다. 하지만 압전 세라믹의 출력 특성은 전압이 크고, 출력 전류가 작은 특성을 지지고 있어 충전 속도가 느리다는 문제점이 있다. 압전세라믹에서 발생되는 에너지는 세라믹의 두께와 세라믹의 전극면적에 비례하는데 각각 세라믹의 두께는 출력 전압에 영향을 주며, 세라믹의 전극면적은 발생하는 전하량에 영항을 준다. 이러한 압전체의 특징을 이용하여 본 연구에서는 압전체의 출력특성의 향상을 위하여 $10\times35mm^2$ 크기의 적층 세라믹을 제작하여 압전에너지 하베스터를 제작하였다. 적층 압전세라믹을 이용한 에너지 하베스터에서 3.5m/$s^2$ 24.6 ${\mu}m$의 진동에서 발생전압 2.14 V 에 발생전류 252 ${\mu}A$의 특성을 얻을 수 있었다.

• Korea Science and Art Forum
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• v.20
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• pp.421-428
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• 2015

Electronic/hybrid car and electroplating rectifier should have switching devices such as SCR, MOSFET, IGBT. And those switching devices should be operated by gate driver. In this paper, we propose high power gate driver that contains H-Bridge using 4 BJTs. H-Bridge and transformer generate isolate power. And gate control signal is transferred to isolated one by photo coupler and operate real switching device. We designed H-Bridge and 555-Timer by PSpice simulation and manufactured real product. Finally we succeed to operate 27V 50,000A electroplating rectifier using proposed gate driver.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.1039-1044
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• 2005

A Multi-channel serial device using the embedded Linux system is designed for a remote controlling and monitoring system. The proposed device consists of a FIFO, a state machine, and an interrupter. The device program written in embedded Linux enables the effective programming of device. While the conventional multi-channel serial devices accesses every individual serial devices, the proposed device accesses the multi-channel serial device as if it is a single serial device. The device efficiently performs the multi-channel serial input/output operation and has fast access time than the conventional multi-channel serial device.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06d
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• pp.76-78
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• 2011

안드로이드 모바일 애플리케이션을 개발할 때 안드로이드 지원 서비스인 인텐트는 로컬 장치 내에서 애플리케이션간 메시지를 전송하고 받을 수 있다. 그러나 서로 다른 장치간의 인텐트를 이용한 메시지 전송은 지원되지 않고 있다. 만약 서로 다른 장치간에 인텐트가 지원이 된다면 끊김 없는 서비스가 가능해진다. 끊김없는 서비스란 사용자가 스마트폰으로 워드나 인터넷검색 등을 하고 있다가 자신이 가진 다른 장치인 TabletPC로 스마트폰에 있던 정보 그대로 이어서 사용하고 싶을 때 끊김 없이 이어서 할 수가 있는 것이다. 본 논문에서는 다른 장치간의 원격 메시지 전송을 위하여 RISP 애플리케이션을 제안한다. RISP 애플리케이션은 구글의 C2DM 서비스를 이용하여 다른 장치간의 원격 메시지 전송을 서비스하는 애플리케이션이다. 개발자가 애플리케이션을 개발할때 RemoteIntent 코드를 작성하면 RISP 애플리케이션은 이 RemoteIntent를 구글의 C2DM을 통해 다른 장치로 메시지를 전송하여 그 장치내의 RISP 애플리케이션이 RemoteIntent를 분석하여 해당 애플리케이션에 인텐트를 넘겨준다. 이렇게 해서 인텐트는 서로 다른 장치간에 인텐트를 넘길 수 있는 것이다. 본 논문에서는 안드로이드 모바일 플랫폼을 대상으로 하여 RISP애플리케이션을 제안한다. 제안하는 RISP는 장치에 애플리케이션으로 설치되며 장치의 안드로이드 버전2.2 이상에서만 구동된다.

• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.731-737
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• 2012

In the present study, a feasibility study on an innovative satellite attitude control actuator is performed. The actuator is specially designed to generate the reaction torque in an arbitrary axis, so that a satellite attitude can be controlled by using itself. It consists of a spherical flywheel and electromagnets for levitation and rotation control of the ball. As the earlier study, a rotating performance test on the spherical actuator is conducted in a single rotating axis and vertical levitation condition. From the test results, it can be confirmed that the maximum speed and torque of the innovative device are 7,200rpm and 0.7Nm, respectively. Using a velocity-voltage characteristic curve of the spherical motor, an open-loop control (V/f constant control) is performed, and the test results show excellent control performance in acceleration and deceleration phases.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.3
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• pp.1-8
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• 2013

Plasma display panel (PDP) televisions are facing to have a new chance to receive attention along with a boom in 3-D software and contents because PDP can provide the comfortable and realistic 3-D images. The PDP has three driving circuit boards such as X, Y and addressing boards. Cost effective driving waveform has already been reported to decrease the number of driving circuit board. Half bridge based sustaining driver can remove a sustaining driver in the X board. However, the biasing circuit in the X driving boards cannot be reduced because there are some drawbacks such as unstable gas discharge condition and unreliability of an address driver IC. In this paper, the half bridge based sustaining driver is considered and a simple address driver is proposed to remove one driving board, X driving board. The stable gas discharge condition, reliability of the address driver IC and the low cost can be obtained by the proposed circuit.

• Plant Journal
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• v.15 no.4
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• pp.36-42
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• 2019

In recent, according to the tightening of environment regulation policy, the height of the site of the power plant is increased and the length of the cooling water pipe is increased. This has a serious impact on the stability of the plant. This study analyzes the transient phenomenon using LIQT 7.2, an unsteady state one-dimensional analysis software, to secure the stability of 1,000 MW high-capacity coal-fired power plant cooling water system with high head. To prevent water hammer, The effects on performance characteristics were predicted by individual and combination application. The surge pressure of the cooling water which occurs when the pump was stopped without installing the anti-surge devices was the largest at the pump outlet side. The most effective and simple way to reduce surge pressure in these cooling water systems is to combine a vacuum breaker with a hydraulic non-return valve, which is an essential device for pump protection.