• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2167-2169
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• 1999

A pulse transformer producing pulses with the peak power of 200-MW (400 kV 500 A at load side with $4.4{\mu}s$ flat-top) is required to drive the 80-MW pulsed klystron in the PLS linac. We have designed and manufactured the high power pulse transformer with 1 : 17 turn ratio. Its primary functions are to match the impedance of klystron tube to the modulators, and to provide step-up of the voltage. To obtain a fast rise time of the pulse voltage. Low leakage inductance and low distributed capacitance design is very important. In this paper, we discuss the equivalent circuit analysis of the pulse transformer, and present the full power performance test results of pulse transformer.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1533-1535
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• 1994

The Monte-Carlo simulation was used to define the physical mechanisms of the initiation phase of pseudo-spark discharge. The pseudo-spark discharge employing the hollow cathode geometry is accompanied by very fast current rising and intense charged particle beams. In this model, time-dependent continuity equation for the electrons and ions were solved consistently with Poisson's equation for the electric field in a two-dimensional, sysmmetrically cylinderical geometry. From the simulation, a sequence of physical mechanisms that cause the rapid current rise associated with the onset of pseudo-spark discharge mode were identified.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.12
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• pp.491-497
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• 1985

An applicaton of the linear optimal control theory to the problem or load follow control in pressurized water reactors (PWR) is investigated. In order to perform the steady-state and load follow operation in PWR, a nonlinear model for the reactor and steam generator is derived and linearized at 50% rated power. Simulation tests are performed for 10% demanded load. Comparing the dynamic response of the newly developed optimal load follow controller with those of the integral error feedback controller proposed by Yang, the rise time of dynamic response of the former is about 15 seconds faster than those of the latter, thus the results indicate that the fast response of the optimal load follow controller is verified. The results of this work are directly applicable to the design of the load follow control systems for commercially operated PWRs.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.974-976
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• 1996

In this paper, a reference model following control system using a fuzzy logic controller(FLC) is proposed By using an integrator and a nonlinear hysteresis element, a reference model whose response has no overshoot and fast rise time is designed. A FLC is designed to follow as close as possible to the response of the reference model. The proposed design method is shown that the robustness and the optimal tracking property can be achieved under modeling error, disturbance and parameter perturbations. The effectiveness of the proposed design method is verified through the simulation that compare using the FLC with using a $H_{\infty}$ controller.

• Proceedings of the Korea Contents Association Conference
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• 2018.05a
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• pp.351-352
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• 2018

With the rise of the Internet era, instant messaging is playing an increasingly important role in the entire Internet market. Nowadays, most of chat softwares on the market are designed for chatting with friends. Before joining a group chat, we must be invited by your friends. On certain occasions, it is very troublesome to invite lots of people quickly if people want to build a group chat temporarily. Therefore I developed a chat application for ad-hoc groups to solve the problem. Ad-hoc groups can be used for some specific occasions for example some large meetings and gatherings. People can create a group at any time any where and other people can join the group chat fast. People that include friends and strangers all can join a group chat by scanning the QR code without adding anyone as friends.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.129-134
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• 2006

Environmental pollution was begun to rise suffering increase in population with fast economic growth after industrial revolution teeth. Be, air pollution out of them, pollution most seriously happen, and began to cope in greenhouse gas danger from this time. Presents greenhouse gas problem is becoming universal interest ago, and our country is becoming problem. Wish to reduce greenhouse gas in world climatic change convention through Gyoto mekanijeum to reduce greenhouse gas. Wish to present standard for consideration in among CDM business, base line formation out of them.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.75-78
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• 1995

Gas source molecular beam epitaxy have been used in the growth of InAlAsAnGaAs MSM-PD structure, in which InAlAs ultra thin layer was used as Schottky barrier enhancement material. High performance MSM-PDs have been constructed on the grown wafer. High breakdown voltage of >30V, low dark current density of $3pA/\mu \textrm{cm}^2$ at 10V bias and fast transient response of <20ps rise time / <40ps FWHM have been measured, which confirm the results that GSMBE is a superior method for the growth of materials with high layer and interfacial quality, especially for InP based InAIAdInGaAs system.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.224-226
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• 2020

본 논문은 빠른 상승 시간과 짧은 펄스폭을 위한 펄스 전원장치의 설계에 대해 다룬다. 이를 위해서 적합한 방전 스위치의 선정과 높은 상승률을 가진 동기화된 게이트 전압을 만들어 내는 게이트 구동 회로의 설계가 진행 되었다. 방전 스위치로 IGBT가 선정되었으며, 방전 스위치들의 동기화된 빠른 게이트 드라이빙을 위한 펄스 컨트롤러 인버터와 게이트 드라이브 회로의 설계 및 동작에 대한 분석이 진행 되었다. 실험을 통해 펄스 컨트롤러 게이트 드라이빙 시스템에 대한 검증이 이루어졌고, 무유도 저항을 사용한 10 kV, 50 kHz 조건에서 펄스 출력 실험을 통해 20 ns 이하 상승시간과 100 ns 펄스폭을 갖는 펄스 전원 장치의 출력을 확인 하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.6
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• pp.360-364
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• 2015

Electronic systems based on solid state devices have changed to be more complicated and miniaturized as the electronic systems developed. If the electronic systems are exposed to HPEM (high power electromagnetics), the systems will be destroyed by the coupling effects of electromagnetic waves. Because the HPEM has fast rise time and high voltage of the pulse, the semiconductors are vulnerable to external stress factor such as the coupled electromagnetic pulse. Therefore, we will discuss about malfunction behavior and DFR (destruction failure rate) of the semiconductor caused by amplitude and repetition rate of the pulse. For this experiment, the pulses were injected into the pins of general purpose IC due to the fact that pulse injection test enables the phenomenon after the HPEM is coupled to power cables. These pulses were produced by pulse generator and their characteristics are 2.1 [ns] of pulse width, 1.1 [ns] of pulse rise time and 30, 60, 120 [Hz] of pulse repetition rate. The injected pulses have changed frequency, period and duty ratio of output generated by Timer IC. Also, as the pulse repetition rate increases the breakdown threshold point of the timer IC was reduced.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.1
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• pp.94-100
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• 2005

This paper presents the behaviors of transient and effective impulse impedances of a long ground rod associated with the current injection points. The laboratory test for the time domain performance of actual-sized model ground rod subjected to a lightning stroke current has been carried out The transient ground impedances of long ground rods under impulse currents were higher than the ground resistance. Both of the ground resistance and the effective impulse ground impedance decrease with increasing the length of the ground rods. Also, the effective impulse ground impedances are significantly increased in fast rise time ranges. The reduction of the ground resistance is decisive to improve the impulse impedance characteristics of grounding systems. When the test current is injected at the bottom of ground rod, the oscillating pulses with high frequency are included on the wave front of ground rod potential and the effective impulse impedances are higher than any other cases.