• The Magazine for Energy Service Companies
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• s.37
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• pp.86-89
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• 2005

삼성에버랜드 에너지절감형 '증기재압축시스템' 개발 · 상용화 성공/ 삼천리 산업기술대 열병합 도입 계약 체결/ LS산전 호남화력에 FD Fan 고압 인버터 설치/ (주)하이세스 절전기 '하이세스' 출시/ 현대차 김관중 동력팀장 '움직이면 커지는 엔트로피 이해' 책자 발간/ 산업자원위원회 에너지기본법 통과/ (주)케너텍 전기판매, 민간 사업자 1호 달성/ 일진전기(주) 최진용 대표 '산업포장'/ 포스코 에너지절감으로 원가 경쟁력 향상/ 울산시 삼성석화 등 에너지 절약 우수업체 선정/ 시민사회 '에너지를 생각하는 사람들의 알찬 모임' 화제/ 신재생에너지센터 공기관 대상 신재생에너지의무화 사업 설명회/ 에너지관리공단 열병합발전 설계자 대상 교육 실시

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.135-138
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• 2001

오늘날 오디오 포맷의 대부분은 마스킹 효과를 이용한 손실 압축 기법(lossy coding)이다. 그러나 고음질을 요구하는 매니아가 있고 DVD등 차세대 멀티미디어 포맷으로 무손실 오디오 압축기법이 요구되고 있고 이를 위해 일반적인 무손실 데이터 압축방법인 PkZip 등으로 압축할 경우 압축비가 약 1.07:1 밖에 되지 않으므로 적절하지 못하여, 디지털 오디오 데이터를 위한 무손실 압축 알고리즘의 연구가 필요하게 되었다. 본 논문에서는 플래이밍(Framing), 상호상관제거(intrachannel decorrelation), 엔트로피 코딩(Entropy coding) 의 세가지 단계로 구성되는 일반적인 오디오 무손실 압축 기법을 효율적으로 압축하기 위해 wavelet transform을 적용한 알고리즘은 제안한다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.532-537
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• 1996

영광 1호기의 일차계통인 원자로 냉각재 평균온도( $T_{avg}$)를 적정값으로 미세조정하여 운전할 때, 2차계통 주요 운전변수인 주증기압력이 상승하고 터빈출력이 상승함을 발견하여 이에 대한 터빈사이클 열성능 변화를 발전소 전체 열평형 계산에 의해 정량적으로 파악하고, 그 원인을 열역학 2법칙에서의 엔트로피개념을 이용한 유용에너지의 최대값인 엑서지이론을 적용하여 분석하고자하였다. 분석 결과 열평형 계산에서는 전체 열량의 대부분인 63.2%가 복수기에서 손실되는 것으로 나타나는 반면, 열역학 제2법칙의 엑서지를 이용한 분석에서는 비가역손실이 주로 터빈(전체 엑서지의 12.7%)에서 일어나고 그 다음이 복수기(5.7%), 급수가열기(2.1%) 그리고 1,2단 재열기 (1.0%)의 순으로 전체 사이클에서 일어나며, 주증기 압력이 상승할 때 터빈 출력이 상승하는 주원인은 주증기의 유용성(엑서지)이 크게 증가하는 것에 비해 터빈사이클에서의 비가역손실은 적게 증가하기 때문으로 나타났다.다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.76-78
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• 2020

본 논문에서는 합성곱 신경망을 이용한 이미지 분류에서 신뢰도와 실제 예측 정확도가 다른 문제점을 해결하기 위하여 변형된 두 가지 목적 함수를 제안하였다. 첫 번째는 기존 교차 엔트로피 함수에 새로이 신뢰도와 정확도의 차이를 더해준 것이고, 두번째는 예측값의 최댓값을 0.5로 제한한 것이다. 새로운 목적 함수를 통해 학습해본 결과 정확도의 차이는 거의 나지 않았고, 신뢰도와 실제 정확도는 매우 근접하게 되는 결과를 얻을 수 있었다.

• Journal of the Korean Geographical Society
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• v.31 no.3
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• pp.469-488
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• 1996

The defining of weather forecasting regions is possible. since the representativeness of regional weather can by reasonably clarified in terms of weather entropy and the use of information ratio. In this paper, the weather entropy and information ratio were derived numerially from using the information theory. The typical weather characteristics were clarified and defined in the homogeneous weather forecasting regions of the southern parts of Korea. The data used for this study are the daily precipitation and cloudiness during the recent five years (1990-1994) at 42 stations in southern parts of Korea. It is divided into four classes of fine, clear, cloudy and rainy. The results are summarized as follows: 1. The maximum value of weather entropy in study area is 2.009 vits in Yosu in July, and the minimum one is 1.624 bits in Kohung in October. The mean value of weather entropy is maximal in July, on the other hand, minimal in October during four season. The less the value of entropy is, the stabler the weather is. While the bigger the value of entropy is, the more changeable the weather is. 2. The deviation from mean value of weather entropy in southern parts of Korea, with the positive and the negative parts, shows remarkably the distributional tendency of the east (positive) and the west (negative) in January but of the south (positive) and the north (negative) in July. It also clearly shows the distributional tendency of the east (postive) and the west(negative) in the coastal region in April, and of X-type (southern west and northern east: negative) in Chiri Mt. in October. 3. In southern parts, the average information ratio maximaly appear 0.618 in Taegu area in July, whereas minimally 0.550 in Kwangju in October. Particularly the average information ratio of Pusan area is the greatest in April, but the smallest in October. And in Taegu, Kwangju, and Kunsan, it is the greatest in April, January, and July, but the smallest in Jyly, July, and pril. 4.The narrowest appreance of weather representativeness is in July when the Kwangju is the center of the weather forecasting. But the broadest one is in April when Taegu is the center of weather forecasting. 5. The defining of weather forecasting regions in terms of the difference of information ratio most broadly shows up in July in Pusan including the whole Honam area and the southern parts of Youngnam when the Pusan-Taegu is the basis of the application of information ratio. Meanwhile, it appears most broadly in January in Taegu including the whole southern parts except southern coastal area.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.413-418
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• 1987

Rates of the reaction for p-nitro benzyl chloride, benzyl chloride and p-methyl benzyl chloride with pyridine in methanol solvent have been measured by an electric conductivity method at 40$^{\circ}$C and 50$^{\circ}$C under various pressures (1∼2000bar). Pseudo first-order rate constants and second-order rate constants were determined. Rates of these reactions were increased in the order p-NO$_2$ < p-H < p-CH$_3$ and increased with temperature, pressure and concentration of pyridine. From those rate constants, the activation parameters were evaluated. The activation volume and the activation compressibility coefficient are both negative values, but the activation enthalpy is positive and the activation entropy is large negative value. From the evaluation of the ground state and transition state which was resulted from substituents and pressure, it was found that this reaction proceeds through S$_N$2 reaction, and S$_N$2 fashion is slightly disappeared as pressure increases.

• Clean Technology
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• v.27 no.3
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• pp.261-268
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• 2021

Equilibrium, kinetics, and thermodynamics of adsorption of acid black 1 (AB1) by coal-based granular activated carbon (CGAC) were investigated with the adsorption variables of initial concentration of dye, contact time, temperature, and pH. The adsorption reaction of AB1 by activated carbon was caused by electrostatic attraction between the surface (H⁺) of activated carbon and the sulfite ions (SO₃^-) and nitrite ions (NO₂^-) possessed by AB1, and the degree of reaction was highest at pH 3 (97.7%). The isothermal data of AB1 were best fitted with Freundlich isotherm model. From the calculated separation factor (1/n) of Freundlich, it was confirmed that adsorption of AB1 by activated carbon could be very effective. The heat of adsorption in the Temkin model suggested a physical adsorption process (< 20 J mol^-1). The kinetic experiment favored the pseudo second order model, and the equilibrium adsorption amount estimated from the model agreed to that given by the experiments (error < 9.73% ). Intraparticle diffusion was a rate controlling step in this adsorption process. From the activation energy and enthalpy change, it was confirmed that the adsorption reaction is an endothermic reaction proceeding with physical adsorption. The entropy change was positive because of an active reaction at the solid-liquid interface during adsorption of AB1 on the activated carbon surface. The free energy change indicated that the spontaneity of the adsorption reaction increased as the temperature increased.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.205-208
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• 2008

In numerical analysis numerical values of thermodynamic properties such as temperature, pressure, specific volume, enthalpy and entropy are required. But most of the thermodynamic properties of the steam table are determined by experiment. Therefore they are supposed to have measurement errors. In order to make noised thermodynamic properties corresponding to errors, random numbers are generated, adjusted to appropriate magnitudes and added to original thermodynamic properties. the neural networks and quadratic spline interpolation method are introduced for function approximation of these modified thermodynamic properties in the saturated water based on pressure. It was proved that the neural networks give smaller percentage error compared with quadratic spline interpolation. From this fact it was confirmed that the neural networks trace the original values of thermodynamic properties better than the quadratic interpolation method.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.5
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• pp.659-664
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• 2013

It is necessary to develop an efficient MVD coding scheme to improve the video coding performance. In this paper, combined codeword and joint codeword are suggested from analyses on statistical distributions of MVD according to the quantization steps and the conventional codeword structure. Based on these codewords, we propose new MVD coding scheme where one of the suggested codewords is employed to encode the MVD according to the coding environment. Simulation results show that the proposed scheme enhances the coding performance without the quality degradation.

• Journal of the Korean association of regional geographers
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• v.20 no.1
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• pp.30-48
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• 2014

Relying on the interaction indices - dominance index, relative strength index and entropy index, this paper analyzes the structural features of urban network in the Seoul metropolitan area with the flows of commuting, business, and freight. Analytical results show that the Seoul metropolitan urban system is vertical, size-dependent, one-way, and the highest city-dominant network rather than horizontal, size-neutral, two-way, complementary one. The network of freight flow is a little bit more symmetrical than the networks of commuting and business. However, the interaction with Seoul is still determinant in all aspects of hierarchical structure, relative strength, and symmetry of flow.