한국공연예술의 자료개관 및 연구현황

유영대 고려대학교 한국학연구소 1996 한국학연구 Vol.8 No.-

Siriraj Stroke Score 따른 뇌졸중 환자 감별의 적합성

유병대,이명갑,서영조,조준,박찬상,이동필 대한응급의학회 2000 대한응급의학회지 Vol.11 No.4

Background: The differentiation between hemorrhagic(HS) and norhemorrhagic(NHS) stroke is the most important first step in the management of acute stroke because clinical management of the two disorders differs substantially. Neuroimaging studies are useful in diagnosing and distinctioning between HS and NHS. The use of clinical variables, such as Siriraj stroke scores(SSS), has led to good sensitivity, specificity and predictive values. The aim of our study was to evaluate the use of the SSS in the Korean population and assess whether it could aid to expedite treatment decisions. Methods: We reviewed 111 cases of stroke patients admitted to our hospital via the emergency department over a 6 months period from July to December 1998. Levels of consciousness, vomiting, headache, and atheroma markers used in the SSS were applied to these patients who met the criteria for a stroke. Results: Of the 111 patients, the SSS classified 83 with sensitivities of 81.1%(NHS) and 73.3%(HS) and positive predictive values of 84.3% and 68.8%, respectively. The overall accuracy rate was 78.3%. Conclusion: Our results suggest that the SSS is not reliable in distinguishing stroke types in the Korean population. Definite neuroimaging studies are needed prior to thrombolytic therapy.

한국문화와 장인의 미학

유영대 고려대학교 한국학연구소 1998 한국학연구 Vol.10 No.-

유압관로의 주파수변화 따른 압력전파특성

유영태,나기대,김지환 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.2

In this paper, an oil hydraulic pipeline is terminated by both rotary sinusoidal flow generator at upstream and oriffice at down stream. The pulsating pressure wave form, generated by the rotary sinusoidal flow generator, is measured by pressure sensor. In the analysis of this paper, a component of the fundamental frequency is obtained by using Laplace transformation. The experimental and analytical results make clear that (1) viscosity is significant role in hydraulic pipe. (2) When pulsating frequency is matched with the natural frequency, resonance frequency occurred periodically. According to the study proposed here, dynamic pressure in a circular oil pipe is expressed in propagation of pressure wave with respect to frequency and Bessel function. The resonance frequency is 108Hz at oil temperature 20℃ in this study. The abrupt change of gain value id due to effect of resonance frequency. The results of experiment are compared with the calculated results, and agreement of both results is fairly good.

유압관로의 임피던스 전달특성

유영태,나기대,모양우,김지환 朝鮮大學校 機械技術硏究所 2003 機械技術硏究 Vol.6 No.2

Design for quite operation of fluid power system requires t h understanding of noise and vibration characteristics of t h system This paper presents a dynamic response of design of hydraulic circuit. Experimental investigations on the attenuation characteristics of pressure ripple in automotive power steering hydraulic pipe with dynamic response of hydraulic pipe line is examined.

정사각 덕트의 출구 영역에서 속도분포에 대한 실험적 연구

유영태,모양우,나기대,임인호 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.2

A numerical simulation has been performed with the non-linear turbulence model proposed by Speziale(1987) coupled with the k-ε equations coming from the renormalization group theory(RNG) derived by Yakhot et al(1992). The fully developed turbulent flow through a straight square duct, involing secondary motion is simulated. This paper represent computations of the interaction between measurement and numerical computation of turbulent flow on velocity distribution of outlet region in a square duct. RNG turbulent model was adapted and compared with the experimental data and the result of Standard k-ε turbulent model. The predictions obtained with the RNG k-ε model show improvements when compared with the Standard k-ε model. Mean velocity, turbulence kinetic energy and Reynolds shear stresses are in quantitiative agreement with the experimental data. We feel that the RNG k-ε model suggested in this paper can be a useful turbulence model for practical engineering

경계조건변화에 따른 동력전달관로의 동특성

나기대,유영태,김지환 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.6

Design for a quiet operation of fluid power system requires the understanding of noise and vibration characteristics of the system. It's not easy to analyze noise problem in hydraulic cylinder used in typical actuator Because they've got complex fluid dynamics. One of the fundamental problems associated with the hydraulic system is the pulsating flow in pipe lines, which can e tackled by the analysis under simplifying assumptions. The present study focuses on theoretic analysis and experimental study on the dynamics of laminar pulsating flow in a circular pipe. We analyze the propagation characteristics of the pressure pulse within a hydraulic pipe line taking into account the pulsating flow frequency variation. We also measure instantaneous pressure pulses within pipe line to identify the transfer functions. We conduct series of experiments to investigate the propagation characteristics of pressure pulse for various pressure of pulsating flow. The working fluid of the present study is ISO VG46 and the temperature ranges from 20 to 60℃ with normal pressure at 4000kPa. The flow rate is measured by using an ultrasonic flow meter. Pressures at fixed upstream and downstream positions are measured concurrently. The electric signals of the pressure sensor are stored and analyzed using a system analyzer(PKE 983 series). The frequency is varied in the range of 10~500Hz. The Reynolds number is kept below 2,000. In the present study, boundary condition was varied by installing a surge tank and an orifice at the end of pipe. Experimental and theoretical results were compared each other under various boundary conditions.

모터구동 밸브 주기적 안전성 확인을 위한 중요도 분류

강대일,성태용,김길유 한국산업안전학회 2002 한국안전학회지 Vol.17 No.2

Safety-related motor operated valve(MOV) safety significance for Ulchin Unit 3 was categorized. The safety evaluation of MOV of domestic power plants affects the generic data used for the quantification of MOV common cause failure(CCF) events in Ulchin Units 3&4 PSA> Therefore, in this paper, MGL(multiple greek letter) parameter β, used for the evaluation of MOV CCF probabilities in Ulchin Units 3&4 probabilistic safety assessment(PSA), was re-estimated and the MOV safety significance was categorized. The re-estimation results of MGL parameter show that the value of(is decreased by 30% compared with the current value used in Ulchin Unit 3&4 PSA. The categorization results of MOV safety significance using the changed value of MGL parameter(show that the number of HSSCs(high safety significant components) is decreased by 54.5% compared with those using the current value of it used in Ulchin Units 3&4 PSA>

성인 원발성 초점성 사구체 경화증의 예후인자

송영수,최훈영,유태현,강신욱,이중민,정현주,이호영,한대석,최규헌 대한신장학회 2004 대한신장학회잡지 Vol.23 No.1

유압관로에서 비정상 압력측압공의 동특성에 관한 연구

나기대,유영태,김지환 조선대학교 에너지.자원신기술연구소 2000 에너지·자원신기술연구소 논문지 Vol.22 No.2

In this study, the analysis of the dynamics characteristics and performance investigation of the pressure measurement in the hydraulic pipe. The exact solution of the frequency response is obtained by using the complicated transfer function. The discrepancy with the exact and the approximate is small, so the approximation solution is adopted to compare the experimental result with the theoretical analysis. The pressure measurement in the hydraulic pipe is caused by length of capillary and according to the end volume size. The experimental and calculate result show that characteristic of the pressure .measurement in the hydraulic pipe varies with the length of capillary and volume size. Therefore present theoretical formulation and experimental result can be used generally in designing and performance evaluation of all the hydraulic pressure measurement in the hydraulic pipe