• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.23-30
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• 2003

본 고에서는 마이크로파 대역에서 우수한 전력특성을 보이는 GaAs HBT를 이용한 광대역 고출력 전력증폭기 설계에 대하여 살펴본다. GaAs HBT의 전력 소자로서의 장점과 설계시 고려해야 할 단위 전력 소자의 설계, 열적 안정성 문제, 바이어스 회로설계, 그리고 광대역 설계 기법에 대하여 간단히 소개한다. 그리고, 본 연구에서 2~6 GHz 광대역 고출력 전력증폭기를 캐스코드(cascode) HBT를 이용하여 설계하였다. 측정 결과, 2 W의 평균 출력 전력, 10 dB의 이득, 24~43 %의 전력 부가 효율을 얻을 수 있었으며, 칩 크기는 $1.6{\times}2.4 mm^2$로서 매우 작았다. 이 결과를 기존에 개발된 GaAs HBT 광대역 고출력 전력증폭기와 비교 분석하였으며, 칩 면적당 대역폭과 출력 전력, 효율이 아주 우수함을 알 수 있다.

• Nuclear Engineering and Technology
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• v.25 no.3
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• pp.470-479
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• 1993

노심설계의 검증을 통하여 설계의 신뢰성이 확인되며 이는 발전소 운전의 안전성과 경제성을 향상시킬 수 있는 발판이 된다. 본 기고문은 국산핵연료가 장전되었던 영광 2호기 4주기의 운전자료 중에서 핵설계와 관련한 인자의 측정치를 설계치와 비교 분석하고 평가하였다. 비교대상이 된 핵 특성인자는 반응도 관련 자료인 임계붕소농도, 제어봉가, 등온온도계수 및 감속재온도계수 둥이고 출력분포 관련자료인 핵반응률 분포, 집합체 출력분포, 반경방향 첨두출력 F_ $\Delta$H/$^{N}$ , 축방향 출력분포, 축방향 첨두출력 Fq(z) 및 노심 평균 축방향 출력편차(AO)등이다. 이들 인자들에 대한 설계치는 측정치와 잘 일치하였으며, 모두 안전성 관련 제한치이내로 만족함을 확인하였다. 또한 운전자료의 비교 분석을 통하여 후속주기의 핵설계에 반영할 수 있는 근거를 마련하였다.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.397-402
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• 1996

A compact excimer laser was developed with coaxial type which the one line cross flow fan is only used. At 1 kHz repetitive operation, average power of KrF laser is 56 watt. In this paper, Design parameter and CR characteristic are investigated for attainment of the compact 1 kHz excimer laser. We have obtained overall efficiency of 1.2% with KrF laser gas. At this time, CR and the variation of laser output are 2.97, $\pm$9%. Laser gas volume and active volume are 10 liter, 1.8(H)$\times$1.2(W)$\times$30(L)=64.8 ㎤, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11C
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• pp.1040-1048
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• 2009

This paper proposes an auto flesh tone balance algorithm for the picture that is taken for people. General white balance algorithms bring neutral region into focus. But, other objects can be basis if its spectral reflectance is known. In this paper the basis for white balance is human face. For experiment, first, transfer characteristic of image sensor is analyzed and camera output RGB on average face chromaticity under standard illumination is calculated. Second, Output rate for the image is adjusted to make RGB rate for the face photo area taken under unknown illumination RGB rate that is already calculated. Input tri-stimulus XYZ can be calculated from camera output RGB by camera transfer matrix. And input tri-stimulus XYZ is transformed to standard color space (sRGB) using sRGB transfer matrix. For display, RGB data is encoded as eight-bit data after gamma correction. Algorithm is applied to average face color that is light skin color of Macbeth color chart and average color of various face colors that are actually measured.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12A
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• pp.1781-1786
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• 2000

본 논문에서는, 적응 간섭 제거기(AIC : adaptive interference canceller)에 사용되는 적응 알고리즘 중 계산량이 적고, 하드웨어적 복잡성이 낮은 최소 평균 자승(LMS)알고리즘의 적응화 상수(constant step size)를 여러 개 사용하여 빠른 수렴 속도와 낮은 평균 자승 에러를 가지는 방법을 제안한다. 최소 평균 자승 알고리즘에서 적응화 상수는 수렴속도와 평균 자승 에러를 제거하는데, 적응화 상수가 증가할수록 수렴속도가 빨라지는 반면, 평균 자승 에러는 증가하게 된다. 이 논문에서는 수렴속도를 증가하는 동시에 평균 자승 에러를 줄이기 위해, 최소 평균 자승 알고리즘에서 세 개의 적응화 상수를 가지는 새로운 검출기를 제안한다. 이 구조에서, 매 반복횟수에 따른 각 그룹 출력 값들을 가지고, 선택(selection)부분에서 평균 자승 에러들을 비교하며, 가장 작은 평균 자승 에러를 나타내는 그룹의 에러 값과 필터 계수 값들이 선택되어져 여러 적응화 상수 최소 평균 자승 알고리즘(several step size LMS algorithm)부분에서 각 그룹의 필터 계수를 갱신하는데 필요한 정보로 이용된다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1261-1266
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• 2017

A random and systematic jitter suppressed delay locked loop (DLL)-based clock generator with a delay-time voltage variance converter (DVVC) and an averaging circuit (AC) is presented. The DVVC senses the delay variance of each delay stage and generates a voltage. The AC averages the output voltages of two consecutive DVVCs to suppress the systematic and random delay variance of each delay stage in the VCDL. The DVVC and AC averages the delay time of successive delay stages and equalizes the delay time of all delay stages. In addition, a capacitor with a switch working effectively as a negative feedback function is introduced to reduce the variation of the loop filter output voltage. Measurement results of the DLL-based clock generator fabricated in a one-poly six-metal $0.18{\mu}m$ CMOS process shows 13.4-ps rms jitter.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.6
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• pp.445-451
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• 2016

This paper introduces a postprocessing method, an iteration method for melody, and an average neural network method for learning a large number of songs in order to improve musically insufficient parts in automatic composition using existing artificial neural network. The melody of songs composed by artificial neural networks is produced according to the melodies of trained songs, so it can not be a specific tonality and it is difficult to have a repetitive composition. In order to solve these problems, we propose a postprocessing method that converts the melody composed by artificial neural networks into a melody having a specific tonality according to music theory and an iteration method for melody by iteratively composing measure divisions of artificial neural networks. In addition, the existing training method of many songs has some disadvantages. To solve this problem, we adopt an average neural network that is made by averaging the weights of artificial neural networks trained each song. From some experiments, it was confirmed that the proposed method solves the existing problems.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.455-460
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• 2004

We have developed a mode-locked ultra-short pulse C $r^{4+}$:YAG laser, as well as a continuous wave C $r^{4+}$:YAG laser. The laser was pumped by a Nd:YAG laser and its characteristics were investigated. In continuous wave mode, we obtained as much as 600 mW at 1.436 ${\mu}{\textrm}{m}$ with pumping power of 6 W, by using an output coupler with a reflectivity of 98%. The power slope efficiency was 10%, when the gain medium was cooled to 19$^{\circ}C$. The tuning range was varied from 1.39 ${\mu}{\textrm}{m}$ to 1.55 ${\mu}{\textrm}{m}$ and the maximum power was 400 mW at 1.492 ${\mu}{\textrm}{m}$ with a 3-plate birefringent filter. The C $r^{4+}$:YAG laser was mode-locked by a Kerr lens mode locking method. Mode locking at 1.436 ${\mu}{\textrm}{m}$was initiated by slightly rocking a mirror mount. But the pulses were very unstable because of the strong water absorption at this region. So we shifted the lasing wavelength to 1.492 ${\mu}{\textrm}{m}$ by using a 3-plate birefringent filter. Then we obtained stable state mode-locking with the maximum average power of 280 mW for a pumping power of 6 W. The pulse width of 43 fs was measured using an autocorrelator and the repetition rate was 104.5 MHz.

• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.226-232
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• 1999

We have investigated the output power performance of a continuous-wave chromium-doped YAG laser ($Cr^{4+}$:YAG laser), pumped by a Nd: YAG laser. With an output coupler of 1% transmission, we obtained as much as 400 mW of the average output power at 1.450 ${\mu}{\textrm}{m}$. The power slope efficiency of 8%, when the gain medium was cooled to 2$0^{\circ}C$. We tuned the wavelength of the $Cr^{4+}$:YAG laser, at pump power of 6 W, by using birefringent filter. As a result, lasing wavelength was tuned from 1.399 ${\mu}{\textrm}{m}$ to 1.532 ${\mu}{\textrm}{m}$, with the maximum output power of 340 mW at 1.4903 ${\mu}{\textrm}{m}$ and the linewidth was 0.21 nm.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.526-534
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• 2014

In this study, single-input transfer function model is applied to forecast monthly mean sea surface temperature(SST) in 2010 at Yeosu in Korean coastal waters. As input series, monthly mean air temperature series for ten years(2000-2009) at Yeosu in Korea is used, and Monthly mean SST at Yeosu station in Korean coastal waters is used as output series(the same period of input). To build transfer function model, first, input time series is prewhitened, and then cross-correlation functions between prewhitened input and output series are determined. The cross-correlation functions have just two significant values at time lag at 0 and 1. The lag between input and output series, the order of denominator and the order of numerator of transfer function, (b, r, s) are identified as (0, 1, 0). The selected transfer function model shows that there does not exist the lag between monthly mean air temperature and monthly mean SST, and that transfer function has a first-order autoregressive component for monthly mean SST, and that noise model was identified as $ARIMA(1,0,1)(2,0,0)_{12}$. The forecasted values by the selected transfer function model are generally $0.3-1.3^{\circ}C$ higher than actual SST in 2010 and have 6.4 % mean absolute percentage error(MAPE). The error is 2 % lower than MAPE by ARIMA model. This implies that transfer function model could be more available than ARIMA model in terms of forecasting performance of SST.