터보機械의 回轉翼뒤의 볼텍스 및 웨익에 관한 硏究

金鍾億 弘益大學校 1979 弘大論叢 Vol.11 No.-

A number of investigators have dealt with the tip of rotating blade in order to improve the design techniques and the performance of the axial compressors. Most of these studies have treated the case of the stationary blade row because of the difficulties of the experiment and the theory. However, it is possible that the results obtained by assuming the moving cascade blade as a stationary blade contain considerable uncertainties. In the present study, the experiment is performed in the downstream of the rotating blade of the axial compressor and the stationary blade theory is applied to the calculation of the moving cascade blade. In the experimental part of the study, a NACA model 65 axial compressor was used and the measurements were performed by a hot wire anemometer. the probe of the anemometer was an end probe of "X" type and the ranges of the primary experimental variables were the following: number of revolution=1380, 1560, 1760rpm. tip clearance=0.020, 0.028, 0.051. From the results of the experiment, it was found that there were two vortices-a tip clearance vcrtex and a scraing vortex--in the case of the rotating blade row, rather than one vortex as in the case of the stationary blade row. The location of the vortices, the strength of the vortices, the average outlet angle deviation and the radial velocity distribution were also obtained. the theoretical formula given by Lakshiminarayana for the case of the stationary blade row was applied to the above two vortices and the calculated results well compare with the measured results.

軸流流體機械의 回轉翼末端間隙에서의 流出偏差角變化에 關한 硏究

金鍾億 弘益大學校 1981 弘大論叢 Vol.13 No.-

At the rotor blade tip in axial turbomachinery, there may exist a secondary flow phenomena including the tip clearance vortex and the scarping vortex and these phenomena may have serious effects on the performance of axial turbomachinery. The results of the present study are as follows: 1. The intensity of the tip clearance vortex was the same as the values for the case of the stationary turbomachinery. 2. Due to the existance of the scarping vortex, the under turn of the outlet deveaion angle near the blade tip was bigger than the case of stationary turbomachinery and increased with the blade tip clearance. 1. 緖 論 2. 케이싱 壁附近의 過流流動에 關한 理論的 解析 2-1 因轉翼列에서 發生하는 2次流動 2-2 翼末瑞間隙過流와 스크레이핑 過流의 評價 3. 2個의 過流에 의한 流出偏差角 3-1 2個의 過流에 의한 2次流動 4. 流出偏差角 4-1 過流코어의 반지름 결정 4-2 過流强度의 決定 5. 結果 및 考察 6. 結 論 At the rotor blade tip in axial turbomachinery, there may exist a secondary flow phenomena including the tip clearance vortex and the scarping vortex and these phenomena may have serious effects on the performance of axial turbomachinery. The results of the present study are as follows: 1. The intensity of the tip clearance vortex was the same as the values for the case of the stationary turbomachinery. 2. Due to the existance of the scarping vortex, the under turn of the outlet deveaion angle near the blade tip was bigger than the case of stationary turbomachinery and increased with the blade tip clearance.

軸流送風機의 翼末端效果에 關한 硏究(Ⅰ)

金鐘億 弘益大學校 1975 弘大論叢 Vol.7 No.-

Detailed survey was made of the tip clearance effects of the rotar blade through a axial flow fan with a low pressure rise (tip clearance/chord length, ratio 0.00765, 0.218), which did not produce free vortex whirl distribution. It was found that (1) at all flows, Rotar Blade tip clearance caused the high pressure drop near the leading edge, where the great difference of the pressure on the pressure surface and suction surface between theoretical value and experimental value appear; (2) as the tip clearance increased, secondary flow caused by the pressure difference between pressure surface and suction surface was induced a opposite flow against the centrifugal, hence the optimum clearance condition was obtained at the tip clearance about 1.5 percent of the chord length. If current design theories was to be valid, tip clearance ratio should be kept near the 1.5 percent of the blade hight.

분자동력학 을 이용한 단순유체 의 열 유체 역학적 현상 에 대한 연구

김종억,안성청,김용섭 대한기계학회 1984 대한기계학회논문집 Vol.8 No.2

본 연구에서는 108개의 아르곤 입자가 Lennard-Jones의 포텐셜함수로 상호작 용하고 있는 고밀도 액체계에 높은 전단율울 작요시켜 외력에 의하여 물성의 변화가 일어나고 있는 비평형상태의 액체가 나타내는 현상을 분자동력학을 이용하여 미시적 인 관점에서 고찰하므로써, 높은 전단하중으로 인하여 윤활유 내부에서 전단응력이 발생하고, 이완되는 과정과 이로 인하여 점성이 저하하는등 비평형상태하의 물성변화 를 예측하는데 도움이 되고자 한다. The stresses in lubricants by external force lead to rise in temperature and drop in viscosty, and the performance of lubricants decrease by this phenomena. The processes of shear stress generation and relaxation are linear under light load condition but those are changed into nonlinearly over a certain limit of load and speed, and this phenomena influences to viscosty change. This study investigates dense fluid which carries property change for high shear rate by using molecular dynamics, and that result can be related to research a behavior of property change of lubricants under high speed and heavy load.

지방정부 특별교통 서비스품질이 이용자만족도와 이용자가치를 통해 기관이미지에 미치는 영향

김종억,황찬규 (사)디지털산업정보학회 2018 디지털산업정보학회논문지 Vol.14 No.3

The differentiation of this study is largely based on the above discussion. First, I would like to examine the main factors that affect the image of the local government's special transport agencies in terms of users and suggest strategic options for promoting the local government's special traffic. Second, a public service approach is very necessary considering the concept of new public transport such as local government special transport, individual use experience and social impact. The purpose of this study is to demonstrate the characteristics of local government special traffic through the five important factors of the service quality which are not capable of objectively measuring the characteristics of the service.

압출관에서의 압력 및 유형변화에 따른 유체유동에 관한 연구

김종억,이한영,홍기배,Kim, Jong-Eok,Lee, Han-Yeong,Hong, Gi-Bae 대한의용생체공학회 1984 의공학회지 Vol.5 No.1

In order to research the flow in the thin wall compliant tube, this present study is attempt to measure the cross sectional area according to change of external pressure and flow by ultrasonic method different from willy used impedance technique for flow analysis about one dimensional Steads flow. The experimental results are as follows. 1) Measurement of cross sectional area ratio by ultrasonic method by comparison with experimental results of impedance technique & theoretical results were well consent. 2) Pressure difference of upstream and down stream is alwap's maximum range at 0.4 < $\alpha$ <0.5, and have no connection with changing external pressure. 3) when the external pressure is fixed and resistance is varied, Self excited oscillation occurs in the region at 0.5 < $\alpha$ <0.6, and oscillation disappear almost at R2>=1.2

비파괴 자기식 검사기의 기계적 특성에 관한연구

金種億 弘益大學校 科學技術硏究所 1994 科學技術硏究論文集 Vol.5 No.-

In this thesis, a method of measuring residual magnetic gradient for magnetic materials by magnetic inspection method, that is to say, one of non-destructive inspection technologies, was analyzed mecanical properties and its hardware was implemented. Uniformity of heat-treatment and contained quantity of carbon in destructive inspection. Non-destructive inspection is a method for estimating of result which will be taken by destructive inspection. This is a study on the measurement of residual magnetic gradient. A theoretical base and the result of inspection was presented and the hardware was constructed.

軸流 流體機械의 回轉翼末端流動의 3次元的 實驗的 硏究

金鍾億 弘益大學校 1987 弘大論叢 Vol.19 No.2

At the rotor blade tip in axial ccmpressor, there may exist the secondary flow -phenomena including the tip clearance vortex and the scraping vortex and fliese phenomena may bring serious effect an the performance of axial compressor. The purpose of this study is to confirm the existance of the vortices and to determine the three dimensional flow around the rotor blade tip. In this study, the velocity components which were normal to the direction of the absolute outlet velocity and parallel with the blade cascade plane were measured at the location of 6mm behind the trailing edge of the cascade plane. These measured values were converted to the velocity components which were normal to the relative outlet velocity and parallel with the blade cascade plane in order to obtain with the velocity distribution. The experimental velocity distributions were obtained with the blade tip clearance of 0.020, 0.028 and 0.051, and at the revolution velocity of 1380,1E60 and 1760 rpm. The results of the present study were as follows. 1. Due to the existance of the scraping vortices, the underturn of the outlet deviation angle near the blade tip was bigger than the case of the stationary cascade and increased with the blade tip clearance. .2. The position of vortices are obtained from the three dimensional flow.

光刺戟으로 誘發된 腦波 異常所見의 分析

金鍾億 大韓神經精神醫學會 1974 신경정신의학 Vol.13 No.1

This study comprises 460 EEGs, taken out of 4979 EEG tracing of Seoul National University Hospital, dated from Jan. 1964 to Dec. 1972. The selected cases were those which had full range of photic stimulation with detailed history available. The result were analysed and summerized as follows: 1) Twenty one cases were provoked by photic stimulation, the provocation ration being 4.57%. They consisted 14 photoconvulsive response, 2 photomyoclonic response and 5 asymmetric driving. 2) The age-group activatd ranged from 6 to 20 years old, the mean age bing 12.1 years. 3) Those who had been clinically diagnosed as myoclonic epilepsy were the most frequenty activated and they all had PCR. Myoclonic epilepsy was followed by mixed seizure and grand mal. 4) The most provocative flicker frequencies ranged from 12 to 16 flicker/sec. 5) The paroxysm occurred during eye-closing stage and sometimes associated with clinical seizure. 6) Among the provoked case, two were television epilepsy.

분자동력학을 이용한 윤활유의 해석적 연구

김종억,김용섭 한국자동차공학회 1984 오토저널 Vol.6 No.1

We applies Molecular Dynamics simulation technics to a system of Lennard-Jones potential interacting Argon liquid to study shear flow behavior. The thermodynamic state of the system is .rho.=35.54 Kg, mole/m$^{3}$, T=86.5.deg. K which is the triple point of Argon liquid. We applies shear rate : .epsilon.=9.26*10$^{9}$ 1/sec in the system. We find the response function, shear viscosity changes, and shear rate build-up as a function of time. We also find the thermal conductivity in a soft-sphere system.