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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.
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.
몰입의 매개를 통한 인터넷사이트 특성의 고객애호도에 대한 영향
김학윤,이호배 대한경영학회 2004 大韓經營學會誌 Vol.17 No.2
Recently some companies utilize internet as a medium to establish the long-term intimate relationship with their customers. In this study, based on the existing literature regarding the commitment, we build a conceptual model linking the characteristics of internet site to the customer loyalty. Using the data from the user of the internet site of mobile phone companies, we test the model. Results show that the informativeness, pleasure, and interactivity of the internet site have some impact upon the customer loyalty through the instrumental and affective commitment.
한란 및 심비디움의 기내 증식에 미치는 생장조절물질의 효과
김학윤,권순태 경북대학교 농업과학기술연구소 2000 慶北大農學誌 Vol.18 No.-
This study was carried out to determine the effects of plant growth regulators on organogenesis from Cymbidium kanran and Cymbidium hybrida. Optimal rhizome formation from Cymbidium kanran was obtained on MS medium with 10 ppm kinetin+2 ppm NAA, and optimal protocorm formation from Cymbidium hybrida was obtained on MS medium with 10 ppm kinetin+0.05 ppm NAA. However, in this study the optimal media for the callus induction from both explants was not identified. Optimal shoot induction from rhizome of Cymbidium kanran was obtained on MS medium with 10 ppm BA+2 ppm NAA and 5 ppm BA+2 ppm NAA. Optimal shoot induction from protocorm of Cymbidium hybrida was obtained on MS medium with 10 ppm kinetin+2 ppm NAA.
김학윤,이근만 청주대학교 산업과학연구소 1998 産業科學硏究 Vol.16 No.-
The acoustic impulse response was studied in order to evaluate qua1ity Initially, the linearity and effects of sample holding conditions on the acoustric signals were demonstrated. Secondly, acoustic signals were obtained at points whlch divide the equator of the sample into 24 equal parts. As a result of the ana1yses, it become evident that the impulse waveform of acoustic signals induced by impact was transmitted along the equator with uniform velocity. The lower transmission velocity in the time domain agreed with the lower peak frequency domain, both theoretically and practically.
김학윤,안상현,황승준,유성종,한종희,김지현,김수길,장종현,Kim, Hak-Yoon,Ahn, Sang Hyun,Hwang, Seung Jun,Yoo, Sung Jong,Han, Jonghee,Kim, Jihyun,Kim, Soo-Kil,Jang, Jong Hyun 한국전기화학회 2012 한국전기화학회지 Vol.15 No.4
전기화학적 환원을 통한 이산화탄소의 활용을 위한 노력은 오래 전부터 계속되어 왔다. 최근에는 액체연료 중 가격이 비싸고 그 활용도가 높은 포름산의 생성을 위한 연구가 많이 진행되고 있지만 실제 포름산을 생성하고 분석하는 과정에서 효율의 개선과 분석에 어려움이 따른다. 따라서 이산화탄소 환원을 이용한 포름산 생성에 필요한 시스템의 제조, 반응 조건의 개발 및 분석 방법의 정량화가 필요하다. 본 연구에서는 이산화탄소의 전기화학적 환원을 통한 포름산의 생성을 진행하고 생성된 포름산의 양을 분석하였다. 실험에 이용된 셀은 양이온 교환막을 사용하는 대용량의 회분형 셀을 이용하였으며 전위차계를 통하여 삼전극에서 전기화학 실험을 진행하였다. 전기화학 실험은 다양한 촉매 금속을 이용하여 선형 전위 주사법과 chronoamperometry를 통해 진행했으며 이 때 기준전극은 염화은 전극을 이용하였고 상대전극은 백금 전극을 사용하였다. 실험을 통해 생성된 포름산의 농도를 high performance liquid chromatography(HPLC)를 통하여 분석하여 시스템의 적정성과 분석 방법의 유효성을 검증하였다. Electrochemical reduction of carbon dioxide has been widely studied by many scientists and researchers. Recently, the production of formic acid, which is expensive but highly useful liquid material, is receiving a great attention. However, difficulties in the electrochemical reduction process and analyzing methods impede the researches. Therefore, it is important to design an adequate system, develop the reduction process and establish the analyzing methods for carbon dioxide reduction to formic acid. In this study, the production of formic acid through electrochemical reduction of carbon dioxide was performed and concentration of the product has been analyzed. Large scale batch cell with proton exchange membrane was used in the experiment. The electrochemical experiment has been performed using a series of metal catalysts. Linear sweep voltammetry (LSV) and chronoamperometry were performed for carbon dioxide reduction and electrochemical analysis using silver chloride and platinum electrode as a reference electrode and counter electrode, respectively. The concentration of formic acid generated from the reduction was monitored using high performance liquid chromatography (HPLC). The results validate the appropriateness and effectiveness of the designed system and analyzing tool.
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.