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동기정류기를 적용한 공진형 하프브릿지의 효율특성에 관한연구
이광택(Gwang-Taek Lee),안태영(Tae-Young Ahn) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-
In this paper results of the experiment which used LLC resonant half bridge DC-DC converter to a portable electrical equipment. LLC resonance Half Bridge DC-DC converter which was used in this experiment improved an efficiency because it reduced switching, conduction losses and with synchronous rectifier. As a result of the experiment, this proposed converter could verified an increase of 2% to the efficiency more than diode rectifier.
전류비교형 동기정류기를 이용한 LLC 공진형 하프브리지 컨버터
이광택(Gwang-Taek Lee),이달우(Darl-Woo Lee),안태영(Tae-Young Ahn),김성철(Sung-Cheol Kim),장찬규(Chan-Gyu Jang),김용주(Young-joo Kim) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-
This paper presents a synchronous rectifier in a LLC half bridge topology. The proposed synchronous rectifier is used to a current driven synchronous rectifier(SR). Voltage driven synchronous rectifier may introduce voltage and current surge during the zero dead times. To solve this problem, we propose to use modified current driven synchronous rectifier. Finally, the prototype is built and comparison on the current and voltage driven synchronous rectifier(SR).
李光澤 淸州大學校 1984 論文集 Vol.17 No.1
A study of history is useful in showing us a great deal of empirical wisdom. Enough attention has been also devoted to the history of accounting so that it is now possible to trace the evolution of accounting from its beginning as stores accounting in ancient Egypt, Babylonia and Assyria to the birth of the double-entry bookkeeping in 14th century Italy, and from this point to its present form in the advanced societies of today. This study attempts to deal with major historical development in the art of accounting and to examine accounting practices from ancient Egypt to the late 15th century Europe. In terms of research source, many of the texts and most of journals and ledgers are difficult to decipher and interpret, so considerable reliance must be placed on existing secondary sources available. A primary concern of ancient accounting, which originated from ancient Egypt founded in about B.C. 4,400, was the systematic record-keeping of receipt and disbursement of taxes levied and administered by King. Such a record of taxes of B.C. 3,500's is known as the oldest one still in existence. In mediaeval times(A.D. 500-A.D. 1,500), accounting made little progress before A.D. 1,000, because it was the so-called the Dark Age. Since A.D. 1,000, in seaport and industrial cities such as Genoa, Florence, Venice and Pisa in Italy, commercial and textile industries flourished very much, which had been affected by the Crusade. This period saw the transformation and development from the step of account ledgers by Massari, a municipal finance officer in 1,340 to the stage of double-entry bookkeeping system in Genoa, Italy. The Del Bene Firm in Florence in which textile industries greatly developed had a system of not only commercial accounting, but also primeval cost accounting, which is shown in its book of the year 1,368. In sum, near the end of the first half of the 14th century, the techniques of an organized recording of transaction experience had been perfected in practice to a degree which justified a book describing the technical sequence of converting transaction event-data into bilateral account data. It was enlarged and developed into cost accounting in the second half of 14th century. In 15th century, Europe branches of Italian big merchandising firms began to disseminate the double-entry bookkeeping pratices to several countries. In Medici Merchandising Firm from 1,441 to 1,444, there were closing process of ledger accounts, preparation of balance sheet and profit-sharing. Summa, the first book about double-entry bookkeeping, which was written and published by Luca Pacioli in Venice in 1,494 made a great contribution to dissemination of double-entry bookkeeping practice. The conclusion is that double-entry bookkeeping system gradually evolved in response to environmental conditions and needs of businessmen of Renaissance Italy and its further growth and development were conditioned and impelled by the ever-changing needs of the entrepreneur and society.