자성유체를 이용한 평판 디스플레이에 관한 연구

徐鍾旭,金眞煥 弘益大學校 科學基術硏究所 1999 科學技術硏究論文集 Vol.10 No.2

In this paper the possibility of using the magnetic fluid for new type of display devices is presented. It has been found that the magnetic fluid initially placed on the electrode can be pushed away from the region by the magnetic field induced by a moderate level of current. As the thickness of the fluid reduces, more of the incident light is reflected from the surface of the electrode resulting in a brighter state of the cell due to the increased surface reflection. A program to simulate the variation of magnetic fluid thickness on the current carrying electrodes has been developed. The CFD(Computational Fluid Dynamics) code developed uses the PDE(Partial Differential Equation) toolbox in MATLAB to calculate the magnetic field distribution around the electrodes. It has been found that the variation of the magnetic fluid surface profile obtained using the developed simulator well fits the experimental results. It has also been found that the speed of the thickness modulation increases as the magnetic permeability decreases.

Cascode 구조의 CMOS LNA 해석 및 제작

서종삼,박종욱,김영석 충북대학교 컴퓨터 정보통신 연구소 2000 컴퓨터정보통신연구 Vol.8 No.1

RF 통신시스템에 이용되는 캐스코드 CMOS 저잡음증폭기를 NOSIS 0.5㎛ CMOS 공정을 이용하여 해석하고 제작하였다. 우리는 커패시터와 EEPROM을 이용하여 온칩 주파수 튜닝 회로를 제안했다. 입력단과 출력단에서의 커패시턴스는 EEPROM을 프로그램 함으로써 가변할 수 있고, 그렇게 함으로써 정확한 주파수 매칭이 이루어 질 수 있다. 이 방법의 이점은 외부 튜닝 요소가 필요하지 않다는 것이다. S-파라미터, 잡음지수, IIP3를 모의실험하기 위해서 회로시뮬레이터인 HSPICE를 이용하였다. 모의실험은 24dB의 이득, 2.7dB의 잡음지수, 그리고 4dBm의 IIP3를 나타내었다. 제안된 저잡음증폭기는 MOSIS 0.5㎛ CMOS 공정을 이용하여 제작되었고, 온칩 RF 프로브와 HP8720 네트워크 에널라이져를 이용하여 측정하였다. 제작된 저잡음증폭기의 이득은 1GHz에서 약 17dB를 나타내었다. A cascode CMOS low noise amplifier(LNA) for the radio frequency communication system has been analyzed and fabricated using the MOSIS 0.5㎛ CMOS process. We proposed an on-chip frequency tuning circuit using the tuning capacitor and EEPROM. The capacitance at the input and output port can be varied by programming the EEPROM, so that the exact frequency matching can be achieved. The advantage of this method is that the off-chip tuning element is not necessary. The circuit simulator, HSPICE has been used to simulate s-parameter, noise figure(NF), and third-order intercept point(IP3). The simulation showed the forward gain(S21) of 17dB, the noise figure of 2.7dB, the IIP3 of 4dBm. The proposed LNA was fabricated using the MOSIS 0.5㎛ CMOS process and measured using the on-chip RF probe and the HP8720 network analyzer. The measured S21 of the fabricated LNA was about 17dB at 1GHz.

공간전압벡터 PWM 방식을 이용한 유도전동기의 속도제어

서영수,하종욱 명지대학교 대학원 1997 대학원논문집 Vol.1 No.-

In this paper, the speed control system of Induction motor was proposed using vector control algorithm and space voltage vector PWM method to improve the dynamic performance of induction motor. The control system is composed of the PI controller for speed control and the current controller using space voltage vector PWM technique. The high-speed calculation and processing for vector control is carried out by TMS320C31 digital signal processor and IGBT module. The proposed scheme is verified through digital simulations and experiments for 3.7[kw] induction motor and shows good dynamic performance.

고층사무소건물의 매스구성을 위한 전문가 시스템의 개발에 관한 연구

서정훈,박상현,권종욱 영남대학교 환경문제연구소 2000 環境硏究 Vol.20 No.1

건축에서의 전문가 시스템은 설계자에게 많은 가상적인 해결안을 반복해서 수집해야할 수고를 줄여주고 모델링이나 정보제공과 같은 정형적인 측면과 설계의 판단, 상황별 특성과 같은 비정형적인 측면을 연결시키는 도구로 작용한다. 본 연구는 고층사무소건물의 설계과정 중 매스 구성 단계에서 중요한 역할을 하는 요소를 찾아내고, 그 요소들의 정형화 및 표준화 작업을 통해 고층사무소건물의 매스구성을 보조하는 전문가 시스템을 개발하는데 그 목적을 두었다. 본 연구에서 얻어진 결론을 요약해보면 다음과 같다. 건축설계작업 중 매스구성 단계를 제한조건을 만족시켜나가는 제한조건 만족모델로 인식할 수 있었으며, 이 제한조건의 일부를 체계화하여 건물의 매스구성을 보조할 수 있는 시스템을 개발하는 것이 가능하였다. 또, 개발된 시스템을 실제 사례를 통해 평가해 본 결과 타당성 있는 결과물을 산출할 수 있었다. In architecture, the expert system helps architects reduce unnecessarily repeated process. It also serves as a tool of linking patterned processes such as medeling and information provision, with unpatterned processes like decision-making process which can produce different results depending on the situation. This study is devoted to develop an expert system which is helpful to find out the important factors in massing process and to assist the massing of high-rise office buildings through patternization and standardization. The conclusion from the study as follows; It is definitely possible to make the expert system recognize the massing process as a process of meeting all the constraints on a step-by-step basis. So, the developed expert system can assist the massing process by systemizing parts of the constraints. It also proved that the developed knowledge-based system can produce proper outputs as its test showed during the study.

병원간호직 근무자의 근속성향 결정요인

서영준,고종욱 한국병원경영학회 1997 병원경영학회지 Vol.2 No.1

This study purports to investigate the determinants of propensity to stay among nursing staff working at Korean hospitals. The independent variables contains three groups of determinants : environmental variables(job opportunity, spouse support, and parent support), psychological variables(met expectations, work involvement, positive affectivity, and negative affectivity), and structural variables(job autonomy, work unit control, routinization, supervisor support, coworker support, role ambiguity, role conflict, workload, resource inadequacy, distributive justice, promotional chances, job security, job hazards, and pay). The sample used in this study consisted of 329 nurses and 175 nurse aides from two university hospitals in Seoul and its surburbs. Data were collected with self-administered questionnaires and analyzed using path analysis. The results of this study indicate that : (1) the following variables, listed in order of size, have significant positive effects on propensity to stay among hospital nursing staff : job satisfaction, met expectations, supervisor support, job security, and positive affectivity, (2) the following variables, listed in order of size, have significant negative total effects on propensity to stay among hospital nursing staff : job opportunity, negative affectivity, and rutinization, (3) the model explains 44.2 percent of the variance in propensity to stay among nursing staff working at two university hospitals, and (4) managerial support for improving the job autonomy, distributive justice, and promotional opportunity for nurse aides are needed.

초기 변형이 있는 일반 회전체 베어링계의 동조 진동응답해석

홍성욱,박종혁,서용규 金烏工科大學校 1996 論文集 Vol.17 No.-

Rotating machinery often encounter excessive vibration due to various sources. Among others, synchronous excitation such as rotating unbalance and initial deformation is acknowledged as essential source affecting the forced vibration of rotor-bearing systems. In the present paper synchronous response is considered in the presence of initial deformation as well as unbalance. The present paper considers general, flexible rotor bearing system, instead of simple rotors as usually adopted in the literature. The present paper intends to reveal the peculiar effects due to initial deformation in general rotor bearing systems which include rotation speed dependent elements and anisotropic nature. Two numerical examples are provided to illustrate the physics of rotor-bearing systems with initial deformations.

염화물을 포함한 콘크리트내의 철근 부식속도에 관한 연구

임서형,문종욱 진주산업대학교 1998 論文集 Vol.37 No.-

The purpose of this study is to estimate the rate of corrosion of reinforcing bar in concrete by setting the content of chlorides, the thickness of covering and the ratio of water to cements as the experimental factors. As a rusult of this study, it is considered that correlation between the water cement ratio, cover thickness, chloride content and corrosion rate of reinforcing bar is very efficient. Also, through the estimation of those factors, it is possible to predict the rate of corrosion of reinforcing bar in concrete. And the equation for prediction is suggested.

수리계획기법을 이용한 효율적 물배분 시스템모델 : 서남부지역을 중심으로

한동욱,서종석 전남대학교 농업과학기술연구소 2000 農業科學技術硏究 Vol.35 No.-

In this study, mathematical programming was applied to solve for optimal water allocation in the south-western part of Korea, where water supply and demand are unbalanced. The water allocation system was developed to meet water balance in the region through water transfer between the Keum and the Young-San Rivers. The result of the study shows that water transfer may satisfy various water demands in the region until the year 2011 without building reservoirs.

양성중력가속도가 조종사의 심방이뇨 호르몬(Artrial Natriuretic peptide)에 미치는 영향

박종관,서만옥,설경환,조경우,박병옥 공군본부 의무감실 1991 항공의학 Vol.39 No.1-2

길안천(경북 안동)의 저서성대형무척추동물 군집변동 및 생물학적 수질평가

조희욱,김경호,노상은,박진영,서을원,이종은 7개 국립대학교 환경연구 논문집 공동발행 위원회 2004 공업기술연구 Vol.4 No.-

A biological assessment of water quality was carried out in Giran stream from May 203 to January 2004. The benthic macroinvertebrates collected seasonally from 5 field sites were identified mostly up to species level. The benthic macroinvertebrates collected from the surveyed sites were composed of 88 species, 68 genera,42 families, 14 orders, 5 class and 4 phyla. The dominance index (DI) showed the high-est as 0.802 at site 5 and the lowest as 1.643 at site 3. Ecological score of benthic macroinvertebrate (ESB) showed the highest as 103 at site 2 and the lowest as 63 at site 3. All surveyed sites were Oligosaprobic that the water quality estimated by ecological score of benthic macroinvertebratc community.