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전원에 에너지가 회생되는 전류형 DC-DC 콘버어터의 해석
김희준,原田耕介 대한전자공학회 1983 전자공학회지 Vol.20 No.4
The current-fed DC-DC converter has only one energy storage reactor in series with the input for any number of outputs and is insensitive to transformer volt-second unbalance. It is considered that these properties of the converter are considerable advantages over other maltiple-output circuits. The steady-state and dynamic characteristic and stability for the current-fed DC-DC con-verter are analyzed in detail. The analysis is carried out by the state-space averaging method for the operation with the duty ratio less than 50% and is confirmed by the experiment. From the evaluation of stability it is identified that the stability of this converter is excellent as compared with that of the conventional buck type converter.
Negative Induced Polarization Responses over a Layered Earth
김희준,Kim, Hee Joon The Korean Society of Economic and Environmental G 1987 자원환경지질 Vol.20 No.3
3층 구조 대지의 음수 유도분극 반응을 디지탈 선형 필터법으로 구하여 검토하였다. 음수의 유도분극 반응은 전기비저항 구조가 K니 Q형일 때 나타나며, K형 구조의 경우 Q형보다 더 뚜렷한 음수의 반응을 보여 준다. 이러한 구조일 때, 유도분극 계수는 전기비저항 분포와 전극 배치의 함수로 주어지며, 표층의 계수만이 음수의 값을 가질 수 있다. 따라서 음수의 유도분극 반응은 표층이 분극성일 때 생길 가능성이 있으며, 그 외의 층의 분극성은 오히려 음수의 유도분극 반응을 줄이는 역할을 한다. Negative induced polarization (IP) responses are examined for a three-layered earth using a digital linear filter method. The negative IP response can occur when the geoelectric section is of type K or Q. The section of type K creates a more pronounced negative effect than that of type Q. For such sections, IP coefficients are determined as a function of the resistivity distribution and the electrode configuration, and only the IP coefficient of the first layer can be negative. As a result, the negative IP response can occur when the first layer is polarizable in the section of type K or Q. and the polarizabilities of the other layers can act to depress the negative response.
Can medial stability be preserved after open wedge high tibial osteotomy?
김희준,Shin Ji-Yeon,이현주,박경현,Jung Chul-Hee,경희수 대한슬관절학회 2020 대한슬관절학회지 Vol.32 No.-
This study evaluated the medial joint stability after high tibial osteotomy (HTO) releasing the superficial medial collateral ligament (sMCL) without cutting and repairing.Twenty-one patients who performed HTO were enrolled. After an L-shaped incision was made in the pes anserinus, the sMCL was released from the distal portion during surgery. After plate fixation, the sMCL was reattached and the pes anserinus was repaired underneath the plate. Plate removal was performed after 31.1 ± 14.2 months. Before HTO, a valgus force of 40 N was exerted at extension for reference values. Before and after plate removal, a valgus force of 40 N was exerted at extension and at a flexion position of 20°. Medial stability was evaluated by measuring the joint line convergence angle (JLCA). The JLCAs in the extension state before HTO and plate removal were 1.64° ± 1.15° and 1.83° ± 1.36°, respectively; there was no significant difference ( p = 0.198). There was also no significant difference in JLCA before HTO and after plate removal ( p = 0.835). There was also no significant difference in JLCA before and after plate removal both at a knee extension and flexion position of 20° ( p = 0.348 and p = 0.456, respectively). Releasing the sMCL without cutting and repairing the pes anserinus underneath the plate during medial open wedge HTO could facilitate the maintenance of medial joint stability.
김희준,Man-Seog Chun,Jin-Su Song,박소영 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.4
Electrospray ionization mass spectrometry (ESI MS) was used, along with gas chromatography-mass spectrometry (GC-MS), to monitor Paal-Knorr synthesis of 2,5-dimethyl-1-phenylpyrrole by condensation of aniline with 2,5-hexanedione. In addition to 2,5-dimethyl-1-phenylpyrrole observed as a single spot by TLC, unexpected dimer size compounds were observed by GC-MS. Dimers and trimers were observed by ESI MS. ESI tandem mass spectrometry was used to select plausible structures for the dimer. ESI MS with or without liquid chromatographic separation is useful for observing oligomeric byproducts with low volatility produced in organic reactions.