• Journal of Labour Economics
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• v.29 no.2
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• pp.171-199
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• 2006

We collected survey data from those who have Vocational Training Teachers' Qualification to investigate the workplace characteristics and job satisfaction of the qualified people. Also, this study analyzed the determinants of the Vocational Training Teachers' monthly wages. Statistically Significant variables were male, age, graduated from graduate school, work duration, total work hours, regular workers, and levels of the certification. Since previous studies argued that the levels of the certification did not have effect on the wage, result of this study suggested that the further study and discussions on the effect of the levels of the certification was needed.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.494-494
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• 2012

최근에 현대 물리학과 과학의 정점에 있는 초전도가속기 같은 고에너지 빔 가속기 시스템에서 Diocotron instability의 연구가 재조명 되고 있다. 환형의 전자 빔 사이로 프로톤 빔을 통과시키는 구조로써 자기장과 회전하는 전자빔의 상호작용에 기초를 두고 있으며 이 환형의 전자 빔이 고에너지의 프로톤 빔을 집속하는 역할을 한다. 하지만 전자빔이 진행함과 동시에 왜곡되는 현상이 발생하는데 이 왜곡되는 현상을 충분히 조절하지 못한다면 프로톤 빔의 손실과 가속하는 빔의 에너지 저하를 초래하게 될 것이고 또한 실험장치 자체에도 큰 결함을 발생 시킬 수 있다. 따라서 Diocotron instability는 가속기를 활성화 하는데 주요한 테마가 될 것이다. 환형의 전자 빔 층은 정전기적 효과로 인해서 안쪽과 바깥쪽의 속도차가 발생하게 되고 이로 인하여 drift instability 가 발생하게 되어서 왜곡이 발생하고 결국에는 몇 개의 소용돌이를 생성하게 된다. 본 연구에서는 이를 2차원 원통형 구조의 Particle-in-cell 시뮬레이션을 통하여 연구하였으며 자기장의 효과에 따른 환형의 전자빔의 왜곡현상을 지연시키는 방안에 중점을 두었다. 특히 자기장의 세기, 전자빔의 밀도, 전자빔 층의 두께, 전자빔의 프로필의 차이에 의한 결과로 연구하였다.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2325-2327
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• 2002

포항 가속기연구소(PAL)에서는 포항방사광가속기(PLS)가 가동을 시작한 1994년 이후 현재까지 사용되어 온 기존의 제어 시스템을 새로운 환경인 EPICS(Experimental Physics and Industrial Control System) 시스템으로 개발하고 있다. EPICS 시스템의 구성은 IOC(Input/Ouput Controller) 와 OPI(Operator Interface)의 2-Layer로 구성되며 이는 MIU(Machine Interfaces Unit), SCC(Subsystem Computer Control System) 그리고 HMI(Human Machine Interface)로 이어지는 기존의 3-Layer 단계 중 SCC단계를 줄여 2-Layer로 구성된다. 이들 두 계층간의 통신은 Client(OPI)/Server(IOC) 구조의 Channel Access를 통해서 이루어진다. 개발중인 EPICS 시스템은 Open Architecture 구조로 IOC와 OPI 각 부분에서 개발시에 사용된 운영체제나 Hardware 를 사용하지 않고 다른 운영체제나 Hardware를 사용하더라도 하나의 공통부분 즉, Channel Access만 있으면 이를 통해 서로 다른 Subsystem IOC의 데이터를 Access할 수 있다. 전체 EPICS 제어시스템 중 저장링 운전의 핵심이 되는 BPM(Beam Position Monitoring) 및 MPS(Magnet Power Supply) 시스템은 IOC부분에 MVME5100(Target Machine) 보드와 vxWorks(Operating System)를 이용하고 OPI부분에는 SUN Workstation(Host Machine)와 Solaris(Operating System)을 사용하여 개발하고 있다. 본 논문에서는 IOC 및 OPI의 설치 절차와 설치 방법에 대해 기술하였다.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1800-1802
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• 1998

The Pohang Light Source (PLS) is a third generation 2 GeV synchrotron machine. An injection kicker modulator is positioned in the PLS storage ring tunnel. The kicker modulator is driving four kicker magnets simultaneously. The kicker magnets produce magnetic field to deflect the stored beam orbit in the storage ring closer to the injected beam from the PLS beam transfer line. The injected beam then falls into the storage ring beam dynamic aperture. The current kicker modulator was upgraded and installed on August 1995. Since then, the kicker modulator has shown very reliable and stable performance. The kicker modulator specifications are ${\sim}6.0{\mu}s$ full width, ${\sim}24$ kA peak current, and 10 Hz repetition rate. Output current waveform is a half sinusoid. Two thyratron switches(EEV CX-1536AX) are used in the kicker modulator. Total accumulated thyratron heater run hour is about 15,000 hours as of May 1998. Measurement result of spatial magnetic field distribution in the kicker magnet shows good uniformity.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1779-1781
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• 1997

The 2.0 GeV Pohang Light Source (PLS) is consisted of a full energy Linac and a storage ring. Four kicker magnets are installed in the storage ring tunnel to move the stored beam orbit in the storage ring closer to the injected beam from the beam transfer line. The injected beam then falls into the storage ring beam dynamic aperture. A kicker magnet modulator drives all four kicker magnets to maintain field balance and also synchronized kick of the beam. The kicker modulator can handle 2 GeV full energy beam. The kicker magnet modulator is installed in the storage ring tunnel and under stable operation. Specification of the kicker magnet modulator is ${\sim}6.0{\mu}s$ pulse-width, 200 ns flat-top width with ${\pm}0.2%$ regulation, ${\sim}24\;kA$ peak current, and 10 Hz repetition rate. Two thyratron switches (EEV CX-1536AX) are used in the system. In this article, design, and experimental results of the kicker magnet modulator are discussed.

• Korean Journal of Materials Research
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• v.5 no.5
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• pp.503-511
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• 1995

금속/실리콘계에 대한 이온선 혼합시의 비정질상 및 결정상 형성여부를 예측할 수 있는 모델(ADF Model)과초기 결정상 예측 모델(PDF Model)의 적용을 실험적으로 조사하기 위하여 Ni/Si계에 대한 이온선 혼합을 온도와 이온선량을 변수로 하여 행하였으며 상형ㅅㅇ과정을 해석하였다. 이온선 혼합은 80keV가속기를 이용하여 상온~20$0^{\circ}C$의 온도 범위에서 1.0 $\times$ $10^{15}$Ar^{+}$/$cm^{2}$~2.0 $\times$ $10^{-16}$Ar^{+}$/$cm^{2}$의 이온선량을 변화시키면서 실험하였고, 상분석은 TEM과 GXRD를 이용하였다. Ni/Si게에 대한 ADF값은 0.804로 양의 값을 가지므로 이온선 혼합시 비정실상이 형성되고, $Ni_{2}$Si상이 다른 화합물상보다 훨씬 큰 음의 PDF값을 갖으므로 초기 결정상이 $Ni_{2}$Si가 될 것을 예측하였다. 이러한 예측은 실험결과와 매우 잘 일치하였다. 이상의 연구결과로부터 ADF 및 PDF모델을 이용하여 박막에서 형성되는 상을 보다 정확히 예측할수 잇음을 알 수 있었다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.195-200
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• 2012

In this study, parameters and requirements of an 120kW class monorail planetary gearbox was analysed and the adaptive planetary gearbox design was selected. The specification of the sun gear, planetary gear and carrier was set and the profile & lead was optimized. The mechanical efficiency of the optimized one and the original one was observed. Dynamo-tester system was used to observe the mechanical efficiency of the planetary gearbox. A dynamo unit was connected with the planetary gearbox which straightened through the motor by a coupling. The standard tooth shape planetary gearbox and modified tooth shape planetary gearbox were used as test pieces and the rotation speed was set from 600 to 6000rpm with 600rpm, 2.5min one step. In order to check the mechanical efficiency of the planetary gearbox, the tests were done as follows. 1) The power loss between driving motor and dynamo tester. 2) Temperature variation by different rotation speeds. 3) Noise variation by different rotation speeds.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.116-121
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• 2004

Simulation of proton irradiation in space is undertaken with a cyclotron accelerator. The cyclotron is capable of accelerating protons up to 200MeV with nominal fluxes near $10^6-10^8\;protons/cm^2/s$. Accelerated protons are irradiated onto a MPC860 for space application. Both the transient and cumulative responses of the device are found due to the proton irradiation. The primary transient response of the device is modification of the stored data in the circuit, whereas intermittent functional interrupts are also found. The cumulative response of the device is the increase of current consumption by the device.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.1035-1039
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• 2010

Activation products generated by photoneutrons in concrete shielding wall around electron linac were estimated for a high energy X-ray container cargo inspection system. Monte carlo code, MCNPX2.5.0 was used for reference system of 9MeV fixed type dual-direction container cargo inspection system installed at major harbors in Korea. Activation products inventory generated by photoneutron (n,$\gamma$) reaction are estimated, and then radiation dose rate is calculated from the results.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.685-686
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• 2007

This paper presents an application of power system fault diagnostic algorithm for the PEFP Proton Accelerator Research Center using neural network. Proposed fault diagnostic system is constructed by the radial basis function (RBF) neural network because it has the capabilities of the pattern classification and function approximation of any nonlinear function. Proposed system identifies faulted section in the power system based on information about the operation of protection devices such as relays and circuit breakers. In this paper, parameters of the RBF neural networks are tuned by the GA-TS algorithm, which has the global optimal solution searching capabilities. To show the validity of the proposed method, proposed algorithm has been tested with a practical power system in Proton Accelerator Research Center of PEFP.