간농양(肝膿瘍)의 외과적(外科的) 처치(處置)

김학윤 대한소화기학회 1978 대한소화기학회지 Vol.10 No.2

CFDN을 이용한 인공잔향기 구현에 관한 연구

김학윤 청주대학교 산업과학연구소 2000 産業科學硏究 Vol.18 No.1

Circulant Feedback Delay Network(CFDN), whose feedback matrix is circulant to control the stability of system and time-frequency response easier than unitary one, were recently proposed. However, the drawback of this structure is that the flatness of frequency response of CFDN is not enough and it is difficult to adjust position of zeros to decrease this problem. Therefore, we represent the usefulness of CFDN to build artificial reverberators and the main parameter to determine characteristics of CFDN in this paper.

고성능 회전익기의 개발동향과 자동회전의 해석기법

김학윤,신병준,Kim, Hak-Yoon,Sheen, Byung-jun 한국항공운항학회 2014 한국항공운항학회지 Vol.22 No.3

Technical history of VTOL aircraft is examined from the early helicopter appearance to recent experimental rotorcraft in order to distinguish the core issues of those aircraft. Performance and technological challenges of some VTOL aircraft such as tilt rotor, convertiplane, gyroplane, and coaxial helicopter are discussed. As a new generation high performance rotorcraft, Sikorsky X2 is intensively investigated. Considering the developmental history of X2, the autorotational ability at high speed is recognized as a core technology. Analytic method of autorotation and some results are shown and presents research subjects related to the future Korean high performance rotorcraft.

다채널 디지털 그래픽 이퀄라이저의 설계

김학윤 청주대학교 2010 産業科學硏究 Vol.27 No.2

The total frequency response of a multi-channel graphic equalizer changed because of the interference effects between equalizer filters in neighboring bands. So many interference compensation algorithms were suggested to compensate the changed frequency responses. The center frequency of the compensation filter of interference compensation algorithm using variable Q-factor is fixed to the center frequency of a equalizer filter. So just with the change of Q-factor, it is difficult to reduces the variation of the gain of overall frequency response and minimize the difference between the actual gain and defined gain. In this study, we present a variable center frequency interference compensation algorithm that reduces the variation of the gain of overall frequency response and minimizes the difference between the defined gain and the actual gain by varying Q-factor of compensation filter as well as the center frequency of compensation filter that is fixed in the previous methods.

낙태에 대한 긍정적인 고찰

김학윤 경상대학교 경영행정대학원 1998 最高管理者課程論文集 Vol.14 No.-

지향 특성을 이용한 Beam-former의 고속 수렴 알고리즘

김학윤 청주대학교 산업과학연구소 2005 産業科學硏究 Vol.22 No.3

This paper describes a fast convergence algorithm to perform the projection and iterative learning between independent component analysis(ICA) and null beam-forming. The proposed method consist of the following two sections: first, subband-ICA-based BSS section with estimation on the direction of arrival(DOA) of the sound source, second, null beam-forming section based on the estimated DOA. The alterative of learning between ICA and the null beam-forming can realize the fast convergence optimization.

산성비가 봉선화(Impatiens balsamina L.) 및 만수국(Tagetes patula L.)의 발아, 생장, 완충능력 및 양료용탈에 미치는 영향

김학윤,이인중,신동현,김길웅,조문수 한국생명과학회 2000 생명과학회지 Vol.10 No.6

This study was conducted to investigate the effect of simulated acid rain (SAR) on germination, growth, acid buffering capacity and nutrient leaching in Impatiens balsamina L. and Tagetes patula L.. In both species, germination was not inhibited at pH 4.0, but the germination rate decreased at the lower pH of 3.0, showing higher rate in Inpatiens balsamina L. than Tagetes patula L.. As the pH decreases, the growth of radicle was markedly decreased than that of hypocotyl in both species. The plant height, root length, leaf area, total dry weight, relative growth rate and net assimilation rate were inhibited by SAR. The acid buffering capacity in the leaves were increased at pH 4.0, on the other hand, it was shown a tendency to decrease at pH 2.0 in both species. As the pH levels decreased from 5.6 to 2.0, the nutrient leaching from leaves was significantly increased in both species. Based on the results, there are a great difference in the responses to SAR between the two species. In general, Tagetes patula L. represented a higher tolerance to SAR than Impatiens balsamina L.. These results suggested that interspecific variation in the acid buffering capacity and nutrient leaching from leaves may be responsible for the interspecific susceptibility to SAR.

UV-B가 강낭콩(Phaseolus vulgaris L.)의 지방산 구성, 지질과산화 및 polyamine 함량에 미치는 영향

김학윤,Kim Hak-Yoon 한국생명과학회 2006 생명과학회지 Vol.16 No.3

To investigate the effects of UV-B on fatty acid composition, lipid peroxidation and biochemical defense responses of plant, kidney bean (Phaseolus vulgaris L.) was subjected to enhanced UV-B irradiation [daily dose : 0.02.(No UV-B) and 11.36 (enhanced UV-B) $kJ\;m^{-2};UV-B_{BE}$] for 3 weeks. UV-B drastically inhibited both height and dry weight of kidney bean. The content of malondialdehyde significantly increased by about 50% after 3 weeks of UV-B irradiation. The ratio of unsaturated to saturated fatty acids of kidney bean was increased by UV-B irradiation. Three major polyamines of kidney bean leaves : putrescine, spermidine and spermine, were observed. All of the polyamine contents were increased with UV-B irradiation. These results suggested that enhanced UV-B radiation caused oxidative stress on lipids and biochemical protection responses might be activated to prevent from damaging effects of oxidative stress generated by UV-B irradiation. UV-B에 의한 강낭콩 식물의 피해양상, 지질과산화, 지질조성 변화와 UV-B에 대한 식물의 방어기작 등을 조사하기 위하여 3주간 UV-B 조사 실험을 수행하였다. UV-B 처리에 의해 초장이 약 22% 정도 감소하는 것으로 나타났다. MDA 함량은 UV-B 처리에 의해 약 50% 정도 증가하는 것으로 나타났다. Glutathione 및 ascorbate acid 함량은 UV-B 조사에 의해 산화형이 증가하고 환원형이 감소하는 것으로 나타났다. UV-B 조사에 의한 지방산 구성 변화를 조사한 결과 당지질 및 인지질 모두 UV-B조사에 의해 포화지방산이 증가하는 것에 반해, 불포화지방산이 감소하는 것으로 나타났다. 강낭콩 잎에는 주로 3종류의 polyamine이 존재하는 것으로 나타났으며, 3종류 모두 UV-B 조사에 의해 증가하는 것으로 나타났다. 본 실험 결과로 볼 때, UV-B 조사는 활성산소를 생성하여 생체막 지질에 직접적인 영향을 미치는 것으로 나타났으며, ascorbate acid, glutathione, polyamine 등의 항산화물질들이 이에 대한 피해를 최소화하기 위하여 작용하는 것으로 나타났다.

구조방정식 모델링과 이론의 경험적 평가

김학윤 호서대학교 사회과학연구소 1998 社會科學硏究 Vol.17 No.1

Structural Equation Modelling(SEM) serves as a critical role in evaluating a theory. SEM s basic framework and various fit indexes are reviewed in this article. Especially, the conceptual rationale of fit indexes are reviewed. Researcher should assess not only the confirmation/disconfirmation of models but also parsimony of models. Researcher should be careful to select some criteria in evaluating a set of nested models because indexes are based on X² values and factors such as sample size, assumptions regarding the independence of latent variates. and estimation methods may influence the adequacy of performance of X² statistics and fit indexes.

머리 움직임을 고려한 3차원 음 재생 방법에 관한 연구

김학윤 한국정보기술학회 2014 한국정보기술학회논문지 Vol. No.

As the 3D Sound reproduction algorithm is the technology that restores the lost spatial cue, which was lost given recording and playback, it obtains information same as the form in sound location, environment, and a sound source, which occurred by granting the spatial distribution information to auditory sense. Many conventional methods are proposed for implementing the 3D sound reproduction system. These methods have the problem which is not focused and considered on an effect of head movement. Hence, This paper develops and implements the adaptive 3D system with head movement sensor to improve previous ones. Performance of the proposed system is evaluated through listening tests. It shows the better results of the method for headphone than speaker and proves the better experimental results of the head movement than those of excluding the head movement. 3차원 음 재생 알고리즘은 녹음 및 재생 시에 잃어버린 공간 정보를 복원시키는 기술로, 청각의 공간 정보를 부여하여 발생된 음원의 위치나 환경과 같은 정보를 얻어 재생시키는 기술이다. 이와 같은 3차원 음 재생 시스템을 구현하기 위해 기존에 많은 기법들이 연구되어 왔다. 그러나 기존의 방법은 청취자의 머리 움직임에 따른 영향을 고려하고 있지 않다는 문제점을 갖고 있다. 따라서 본 연구에서는 청취자의 머리 움직임에 따른 영향을 고려하기 위하여 머리 이동 감지 센서를 부착하여 움직임에 적응할 수 있는 시스템을 구축하고, 청취 실험을 통하여 구현한 시스템의 성능 평가를 수행하였다. 그 결과, 방향의 인지에 있어서 스피커를 이용한 방법보다 헤드폰을 이용한 방법이, 머리움직임이 없는 경우보다 있는 경우가 더 좋은 결과를 얻었다.