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펄스폭제어방식을 이용한 Switching Regulator에 관한 연구
박규태,윤형로,최승국 연세대학교 산업기술연구소 1981 논문집 Vol.13 No.2
본 논문에서는 Switching Regulator 내의 PWM 시스템에서의 위상지연과 스위칭소자의 지연에 의한 위상지연을 고찰하였고 출력필터의 연속전류모드와 불연속전류모드의 궤환에 의한 시스템의 특성을 분석하였다. 또한 Surge에 의한 Normal mode 잡음과 Ground 잡음전류에 의한 Common mode spike 잡음의 원인을 분석하고 그 대책을 강구하였으며 실제 스위칭 레귤레이터의 제작에 필요한 회로구성과 소자의 선정요건을 고찰하여 효율 82.6%, spike 잡음 10mvp-p 이내의 안정되고 특성이 우수한 레귤레이터를 설계하였다. The phase shift in PWM System due to the time delay in the switching elements has been studied. Employing the normal model, various performance characteristics of the converter for both continuous current operation and discontinuous current operation are compared. The normal mode noise generated by surge and common mode noise generated by ground noise current have been studied. To decrease the noise, several methods are introduced. Hardware circuits are built and in experimental measurements, it shows a high efficiency of 82.6% and low spike noise of 10mv p-p max.
박노국,강신한,장성국 尙志大學校 生産技術硏究所 1998 生産技術論叢 Vol.- No.4
The software consists of GUI module for windows environment on PC and section property calculation module. User selects the section type in menu for beam library on window and inputs the shape data using dialog box displayed by GUI module. The calculation module calculates its properties such as area, centroid, moment of inertia, torsional constant, etc.. By using the developed software, the time for calculation, conversion and management of data can be reduced and it is able to promote the efficiency of analysis and design takes. In this paper described is the software developed to calculate the physical properties of typical beam section.
박노국,이종욱,이승철,이종대,류시옥,이태진 영남대학교 공업기술연구소 2000 工業技術硏究所論文集 Vol.28 No.2
The zinc titanate sorbents(ZTG40) were prepared and the tests for durability and attrition resistance were carried out to develop the highly effective desulfurization sorbents. In the attrition tests for ZTG40 the results showed that the attrition resistance was 94.08% and that the sulfur capacity was maintained above 15g S/100g sorbent throughout the 100-cycle test, its maximum being 23.05g S/100g sorbent. As compared to sorbents developed by the developed countries, ZTG40 showed superior performances. In the advanced countries 15g S/100g sorbent is a yardstick of excellency for the sulfur capacity of desulfurization sorbents. Therefore, ZTG40 developed in this study has the desirable physical and chemical properties for fluidized desulfurization of coal gases.
綿布에 대한 N-methylolacrylamide 處理의 效果에 관한 硏究
朴燦憲,都成國 東亞大學校附設基礎科學硏究所 1985 基礎科學硏究論文集 Vol.2 No.1
In order to improve the crease recovery and dyeing property of the cotton fabric, it was treated with Ν-methylolacrylamide (NMA). Several treating conditions, which include the concentration of NMA, curing temperature, curing time and concentration of catalyst(NH₄Cl), were varied. The acrylamidomethylated cellulose(AMC) fabrics treated with conditions above were dyed with acid dye(C.I. Acid Yellow99) containing nucleophilic group in alkaline bath. The crease recovery, handle value, color-difference and amount of dye of of dayd AMC were investigated. 1. The crease recoverry, handle value, amount of dye on the fabric and color difference are increased with increasing the concentration of NMA. 2. With the increase of curing temperature, the color-difference is increased, the maximum value of crease recovery is found at 140℃, and the handale value is decreased. 3. In accordance with the lapse of curing time, the crease recovery and the color-difference, however slightly over 6 minites, are increased, and the handle value is decreased. 4. The crease recovery, handle value, and color-differdnce are not varied remarkably by increasing the concentration of catalyst in aqueous NMA solution.
러프집합을 이용한 통합형 채권등급 평가모형 구축에 관한 연구
박기남,이훈영,박상국 한국경영과학회 2000 韓國經營科學會誌 Vol.25 No.3
Many different statistical and artificial intelligent techniques have been applied to improve the predictability of credit rating. Hybrid models and systems have also been developed by effectively combining different modeling processes of combining the outcomes of individual models. In this paper, we introduced the rough set theory and developed a hybrid credit rating system that combines individual outcomes in terms of rough set theory. An experiment was conducted to compare the prediction capability of the system with those of other methods. The proposed system based on rough set method outperformed the others.
3차원 직육면체 대공간 내에서의 열 및 기류 유동에 관한 연구
박원희,이상엽,황문섭,김태국 중앙대학교 기술과학연구소 2002 기술과학연구소 논문집 Vol.32 No.-
본 연구에서는 대공간 내에서의 열 및 기류 유동 현상을 연구하기 위하여 464×300× 950mm^3크기의 축소 모형으로 아트리움을 제작하였다. 가상 화재를 모사하기 위하여 대공간 하단에 히터를 설치하였으며, 히터의 온도에 따른 대공간 내의 온도분포를 측정하였다. 본 실험에서 얻은 결과는 아트리움과 같은 대공간에서 화재가 발생하였을 경우에 열 및 기류 현상을 해석하기 위한 기초자료 및 열유동 현상을 해석하는 수치해석 프로그램의 계산 결과의 기준 데이터로도 이용될 수 있을 것이다.
박노국,유성구,서길수,이태진 영남대학교 공업기술연구소 2000 工業技術硏究所論文集 Vol.28 No.2
The sulfidation reaction of calcium carbonate to remove H2S were investigated. Expecially, the effect of polymorphs of calcium carbonate and reaction temperature on the sulfur capture were determined. It was found that calcination reaction of calcium carbonate were influenced by polymorphs of calcium carbonate. The calcination temperatures of aragonite were lower than those of other calcium carbonates. For the sulfidation of calcite with H2S, the effect of reaction temperature on the sulfur capture were not found. But in caes of vaterite and aragonite, the reaction temperature were found to have a significant effect on the sulfidation reaction. From in these results, optimum temperatures of sulfidation reaction using vaterite and aragonite were determined at 800∼850℃ and 750℃, respectively.
산소와 연소 단원에서 과학적 개념 형성을 위한 수업 전략의 효과
엄상수,고영환,백성혜,박국태 한국교원대학교 과학교육연구소 2000 청람과학교육연구논총 Vol.10 No.1
The purpose of this study was to investigate the effectiveness of teaching strategies for scientific conceptions in the units of oxygen and combustion in elementary school science textbook. 70 elementary school 6th grade students in Seoul participated. They were divided into experimental group and controlled group. Five scientific concepts were adopted from the units of oxygen and combustion in the 6th grade science textbook. Subjects' preconceptions were investigated by pre-questionnaires. A series of 6 instructional sessions based on the teaching strategy of cognitive confliction theory were given to the experimental group. By the end of the instructional session, a post-test was administered to both experimental and controlled groups. There was a statistically significant difference between post-test gains of the experimental and controlled groups. These results support the notion that the teaching strategy was effective for changing from preconceptions to scientific concepts.