• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.154-154
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• 2018

To interpret the climate projections for the future as well as present, recognition of the consequences of the climate internal variability and quantification its uncertainty play a vital role. The Korean Peninsula belongs to the Far East Asian Monsoon region and its rainfall characteristics are very complex from time and space perspective. Its internal variability is expected to be large, but this variability has not been completely investigated to date especially using models of high temporal resolutions. Due to coarse spatial and temporal resolutions of General Circulation Models (GCM) projections, several studies adopted dynamic and statistical downscaling approaches to infer meterological forcing from climate change projections at local spatial scales and fine temporal resolutions. In this study, stochastic downscaling methodology was adopted to downscale daily GCM resolutions to hourly time scale using an hourly weather generator, the Advanced WEather GENerator (AWE-GEN). After extracting factors of change from the GCM realizations, these were applied to the climatic statistics inferred from historical observations to re-evaluate parameters of the weather generator. The re-parameterized generator yields hourly time series which can be considered to be representative of future climate conditions. Further, 30 ensemble members of hourly precipitation were generated for each selected station to quantify uncertainty. Spatial map was generated to visualize as separated zones formed through K-means cluster algorithm which region is more inconsistent as compared to the climatological norm or in which region the probability of occurrence of the extremes event is high. The results showed that the stations located near the coastal regions are more uncertain as compared to inland regions. Such information will be ultimately helpful for planning future adaptation and mitigation measures against extreme events.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.295-300
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• 2001

A variety of high voltage DC power supplies employing the high frequency inverter are difficult to achieve soft switching considering a quick response and no overshoot response under the wide load variation ranges which are used in medical-use x-ray high voltage generator from 20kV to 150kV in the output voltage and from 0.5mA to 1250mA, respectively. The authors develops soft switching high voltage DC power supply designed for x-ray power generator applications, which uses series resonant inverter circuit topology with a multistage voltage multiplier instead of a conventional high voltage diode rectifier connected to the second-side of a high-voltage transformer with a large turn ratio. A constant on-time dual mode frequency control scheme operating under a principle of zero-current soft switching commutation is described. Introducing the multistage voltage multiplier, the secondary transformer turn-numbers and stray capacitance of high-voltage transformer is effective to be greatly reduced. It is proved that the proposed high-voltage converter topology with dual mode frequency modulation mode control scheme is able to be the transient response and steady-state performance in high-voltage x-ray tube load. The effectiveness of this high voltage converter is evaluated and discussed on the basis of simulation analysis and observed data in experiment.

• 한국수자원학회논문집
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• 제42권11호
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• pp.1017-1028
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• 2009

SRPM (Neyman-Scott Rectangular Pulse Model)은 수문학분야에서 널리 쓰이고 있는 강수생성모형이다. NSRPM을 구축하기 위해서는 총 5개의 매개변수를 추정하여야 한다. 일반적으로 사용되는 모멘트를 이용하여 매개변수를 추정할 경우, 사용되는 목적함수의 증가에 따라 추정되는 매개변수의 결과가 평탄해지고 목적함수를 추가하거나 조정하기 위해서는 복잡한 수식을 다시 계산해야 하며 추정된 매개변수가 무작위변수 생성 모형에 따라 상이한 결과를 나타내는 단점이 있다. 본 연구에서는 직접적인 매개변수 추정방법을 제시하여 모멘트를 이용한 매개변수 추정의 단점을 극복하고자 하였다. 직접적인 추정방법을 적용하기 위하여 NSRPM의 강수 생성 개수에 따른 통계치 변화를 모의하여 직접적인 추정을 위한 모형을 구축하였다. 기상청 청주 지상관측소의 관측 강수 자료를 사용하여 모멘트를 이용하여 추정된 매개변수와 직접적인 방법을 이용하여 매개변수를 추정하였다. 총 4 개의 무작위변수 알고리즘을 적용하여 강수를 생성하였고, 관측 강수 시계열을 이용하여 정확도를 비교하였다. 비교 결과 직접적인 추정방법이 모멘트를 이용한 매개변수 추정방법보다 안정적이고 높은 정확도를 보이는 매개변수를 추정하는 것으로 나타났다.

• 전력전자학회논문지
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• 제9권2호
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• pp.150-157
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• 2004

본 논문에서는 아날로그형 전력 계통 시뮬레이터에 적용하고자 개발 중인 TCSC(Thyristor Controlled Series Capacitor) 시뮬레이터 시스템 제어기의 하드웨어와 소프트웨어 구성에 대하여 제시하고자 한다. 본 연구에서 개발하고자하는 TCSC 시스템의 제어기는 기존의 전력 계통 시뮬레이터의 여러 제어기들과 통합되어 전력 시스템의 특성을 제어하는 장치이기 때문에 제어기는 전력 시스템의 각종 주요 파라메터를 실시간으로 통신할 수 있어야 하며 주어진 시간 내에 제어 기능을 수행할 수 있어야 한다. 따라서, 이러한 요구 조건을 만족시키기 위해서는 제어기 하드웨어의 설계와 구성이 매우 중요하다 본 논문에서는 TCSC 시스템의 복합적인 기능 수행을 위한 제어기 하드웨어와 소프트웨어 구조에 대하여 제시하고자 한다. TSCS 제어기는 고속 부동 소수 연산이 가능한 DSP(Digital Signal Processor) 플랫폼과 실시간 RTOS(Real Time Operating System)로 구성되어 있다.

• 한국안전학회지
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• 제25권2호
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• pp.29-34
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• 2010

This paper is aimed to develop monitoring software for detecting the characteristics of current and voltage signals for series arc on electric wire. In order to attain this purpose, the characteristics of series arc were analyzed by the current and voltage signals on electric wire which were installed, and also analyzed by the changes of RMS, instantaneous of waveform value in time domain and THD in frequency domain. Monitoring program which analyze the signal was developed by Labview which can analyze in time domain and frequency domain, and save data. Experimental setup for detecting verification of monitoring program was composed loads of a lamp, an electric heater and an electric fan loads which were usually using. Measurement points for detecting verification of monitoring program were selected at both the panel board and the arc generator at the same time. As results of the experiments by monitoring program, the arc current waveform showed the same characteristic in all measurement points of all load. But the arc voltage waveform was different in each measurement point. When arc occurred, the THD of current value increased above 20%. The results of this study will be effectively used in developing the preventive system of electric fire by series arc.

• 전기의세계
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• 제22권1호
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• pp.9-19
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• 1973

This paper is for the supplementary studies of the theoretical treaties on the machine dynamics of the amplidyne generator under the influencies of the armature reaction. The author has already shown the time-domain expression of the dynamic relations of the machine with balanced control winding, under this operating condition. In this paper, analytical and experimental studies of a test machine are intended to supplement the theories derived in the previous work, entitled "On the dynamics and the demagnetization effect of the amplidyne generator with auxiliary feedback compensating winding". FACOM 230 digital computer is incorporated for processing of a series of experimental data. The machine dynamics are then numerically analyzed with the aid of the computer. The virtual machine responses to stepwise inputs are compared with the computer output to confirm the influence of the armature reaction effect on to the machine dynamics. dynamics.

• 신재생에너지
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• 제10권4호
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• pp.22-28
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• 2014

The thermoelectric generator using solar heat was applied to the device (heat-electricity conversion device) to produce small-scale electricity. The purpose of this study was to investigate the characteristics and performance of the device, which equipped with heat pipe as heat source. The experimental results showed that efficiency of circular single evacuated solar collector was higher 2.7 times than that of rectangular solar collector. Furthermore maximum power of 5 watt was obtained when 2 devices with series array were used and it could be more improved by increasing the number of device or measurement time.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.865-868
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• 1993

This paper describes a simple random signal generator employing by CMOS analog technology in current mode. The system is a nonlinear dynamical system described by a difference equation, such as x(t＋1) = f(x(t)) , t = 0,1,2, ... , where f($.$) is a nonlinear function of x(f). The tent map is used as a nonlinear function to produce the random signals with the uniform distribution. The prototype is implemented by using transistor array devices fabricated in a mass product line. It can be easily realized on a chip. Uniform randomness of the signal is examined by the serial correlation test and the $\chi$2 test.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(3)
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• pp.5-8
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• 2000

Voltage mode chaotic neuron has been designed in integrated circuit and fabricated by using 0.8$\mu\textrm{m}$ single poly CMOS technology. The fabricated CMOS chaotic neuron consist of chaotic signal generator and sigmoid output function. This paper presents an analysis of the chaotic behavior in the voltage mode CMOS chaotic neuron. From empirical equations of the chaotic neuron, the dynamical responses such as time series, bifurcation, and average firing rate are calculated. And, results of experiments in the single chaotic neuron and chaotic neural networks by two neurons are shown and compared with the simulated results.

• 한국추진공학회지
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• 제24권4호
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• pp.55-65
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• 2020

본 논문에는 75톤급 액체로켓엔진 가스발생기의 개발시험과 수락시험 결과가 기술되어 있다. 현재까지 44기의 가스발생기 모델을 이용하여 330회 이상, 누적 연소시간 7,000 초 이상의 가스발생기 단독 시험이 수행되었다. 시험을 통해 75톤급 가스발생기가 연소압력, 연소효율, 압력손실, 연소안정성, 연소가스 온도 등에서 신뢰성과 재현성이 높은 특성을 보여준다는 것이 확인되었다. 한국형발사체용 75톤급 가스발생기의 마지막 시리즈에 해당하는 5기는 2019년 말까지 제작 완료되어 2020년 상반기에 수락시험이 수행될 계획이다.