• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.270-273
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• 1996

This paper describes a type of piezoelectric transformer with improved design principles. It consists of a thin rectangular piezoelectric ceramic plate having two input electrodes and one output electrode. The length of each input and output electrode is nearly one third of that of piezoelectric transformer itself. In the driving section, the ceramic plate is poled in the thickness direction reversely with each other, and has electrodes on both main faces. The electric input near its fundamental resonance frequency is applied to the driving section in parallel and the output voltage from the generating section is connected to the resistor load. Its equivalent circuit is derived from the Mason\`s model. The frequency characteristics near the resonance frequency under no load have been investigated. Moreover, using this piezoelectric transformer we measured the LCD backlight characteristics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.492-494
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• 2002

The fundamental principles of the operation of microwave discharges that are used to convert microwave energy to broad spectrum visual light are known. In this paper, emission dependance of microwave discharges in mixture content of sulfur with noble gases was studied. It is shown that the excitation of this gaseous mixture is carried out in two phases: (1) ionization of noble gas atoms by a microwave field and (2) the consequent maintenance of slightly ionized nonequilibrium plasma by the field. These two processes have essentially various thresholds for the microwave pump. The purpose of this work is to investigate spectral properties of the high frequency discharges in a mixture sulfur vapors with noble gases.

• Journal of the Optical Society of Korea
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• 제1권1호
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• pp.52-59
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• 1997

In this paper, we propose a system design for a parallel3-dimensional optical interconnection network utilizing variable grating mode liquid crystal devices (VGM LCD's) which are optical transducers capable of performing intensity-to-spatial-frequency conversion. The proposed system performs real-time, reconfigurable, but blocking and nonbroadcasting 3-dimensional optical interconnections. The operating principles of the 3-D optical interconnection network are described, and some of the fundamental limitations are addressed. The system presented in this paper can be directly used as a configuration of switching elements for the 2-D optical perfect-shuffle dynamic interconnection network, as well as for a B-ISDN photonic switching system.

• 대한조선학회지
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• 제10권1호
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• pp.1-14
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• 1973

In the Department of Naval Architecture, Seoul National University, the development of computer programs for the computer-aided ship design sponsored by the Ministry of Science and Technology has been begun. The project is to be accomplished as a four-year plan, and the results of the works of the first year, preliminary design of dry-cargo ships based on an optimization technique and some fundamental calculations accompanied with the basic design of ships such as calculations of displacement, hydrostatic characteristics of hull forms, stability, floodable length, load line and longitudinal section modulus, are given in the Report R-72-9[9] published by the sopnsor for the public interests. In this paper, the philosophy and methodological principles with which the preliminary design program given in Appendix II was developed are summerized.

• International Journal of Railway
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• 제5권4호
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• pp.167-174
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• 2012

As wireless power transfer (WPT) technologies emerge in a wide range of applications including public transportation, many expect that applying the technology to the current railway systems will bring positive effects to current railway systems. In this paper, we introduce design methodology of a WPT system for railway application. Fundamental principles of magnetic fields and a WPT circuit are first analyzed, and advantages and efficiency of a possible train system are discussed. It then examines other significant factors such as performance requirements and EMC criteria to design a wireless train system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.796-805
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• 2008

Safety Management of Korean railway industry has been rapidly changed into a risk-based approach adopted by developed countries since Railway Safety Act 2004, Rolling Stock Risk Assessment Guidance and its following regulations came into force. The fundamental requirements for the risk-based safety management is to carry out a systematic hazard identification and quantified risk analyses including cost-benefit analyses, but there has been rare a serious discussion over risk acceptance criteria and value of life in order to be able to judge the results of risk analyses and carry out cost-benefit analyses. This study presents the results of a review of risk acceptance criteria and value of life which may be adoped to Korean railway industry through the analyses with comparison of risk accepatnce principles and risk accepatnce criteria which have been already applied to other countries or other railway operators.

• Korean Journal of Acupuncture
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• 제28권1호
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• pp.113-123
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• 2011

Objectives : This study is to provide a clear interpretation of Pyoyubu (標幽賦) which was written by Tu han kyoung (竇漢卿) during the Kum-Won dynasty of China (A.D 1196-1280). Methods : The translation was based on Original Chimgudaesung (原本鍼灸大成) and revisals on Chimguchuiyoung (鍼灸聚英), Yukyoungbuik (類經附翼), New Chimgudaesung (新鍼灸大成), etc. The critical review part helps to better understand acupuncture & moxibustion world. Results & Conclusions : The book covered all of the concepts involved in acupuncture theory and techniques. It provides a foundation and remains a key reference work for the current theory of acupuncture. An in-depth study of the book leads as follow ; 1. To full understanding of the fundamental principles of these fields. 2. To drawing up clinical practice guidelines for doctors toward patients. 3. To promoting the beneficial effects of acupuncture treatment.

• 설비공학논문집
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• 제7권1호
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• pp.20-29
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• 1995

A theoretical model for film condensation of a vapor including a relatively lighter noncondensable gas on a horizontal tube has been formulated on the basis of the conservation laws and other fundamental physical principles. The model is applied to the prediction of the condensation heat transfer characteristics for the Freon vapor in the presence of air on a horizontal tube. Calculated results for the mean heat transfer coefficient, which is shown to depend strongly on the bulk concentration of air, are in good agreement with the available experimental results for a range of operating conditions. The distributions of physical quantities along the surface of tube are also calculated, such as the boundary layer thickness and local heat transfer coefficient. The present model is readily reduced to the Nusselt model as the bulk concentration of air decreases to zero. Therefore, the transition from the condensation of pure vapor to that of vapor-air mixture occurs continuously not abruptly.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2004년도 추계학술발표대회 논문집
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• pp.102-107
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• 2004

In order to understand the characteristics of the Japanese conception of space, we examined the characteristics of Japanese human geography, schools of thought, and aesthetics through the examinations on relevant documents. In addition, we reorganized such cultural backgrounds in relation to the Japanese perception of space, extracting the fundamental principles and elements of Japanese space composition and examining their significance. We propose a structural framework for understanding and analyzing Japanese space based on the reciprocal relationship and meaning among the various elements of Japanese space. Using this analytical framework, we studied the representative works of Japanese interior space, concluding in an analysis of the expressive characteristics of the Japanese notion of space.

• Structural Engineering and Mechanics
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• 제53권1호
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• pp.105-130
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• 2015

In this paper, the classical continuum mechanics is adopted and modified to be consistent with the unique behavior of micro/nano solids. At first, some kinematical principles are discussed to illustrate the effect of the discrete nature of the microstructure of micro/nano solids. The fundamental equations and relations of the modified couple stress theory are derived to illustrate the microstructural effects on nanostructures. Moreover, the effect of the material surface energy is incorporated into the modified continuum theory. Due to the reduced coordination of the surface atoms a residual stress field, namely surface pretension, is generated in the bulk structure of the continuum. The essential kinematical and kinetically relations of nano-continuums are derived and discussed. These essential relations are used to derive a size-dependent model for Mindlin functionally graded (FG) nano-plates. An analytical solution is derived to show the feasibility of the proposed size-dependent model. A parametric study is provided to express the effect of surface parameters and the effect of the microstructure couple stress on the bending behavior of a simply supported FG nano plate.