와이어컷 방전가공기의 가공표면 특성에 관한 연구

이종혁,박달근 忠州大學校 2005 한국교통대학교 논문집 Vol.40 No.2

From the experimental study of wire-cut Electric Discharge Machining of high speed steel(SKH2), the surface roughness characteristics such as work voltage and work current for maximum peak to valley roughness beight, the third point height. Experiments is surface roughness for sampling length determine of measuring length of work voltage 2V, 3V, 4V, 5V and work current 22A, 24A, 26A, 28A. Maximum peak to valley roughness height increased is work voltage increased and work current increased with most suitable cutting condition at 3V maximum peak to valley roughness height decreased. The third point height is work voltage and work current increased with most suitable cutting condition at 2V28A the third point height decreased.

Gumbel-Chow 法에 의한 確率渴水量의 誘導 및 比較 分析

李淳赫,朴鐘國 충북대학교 농업과학기술연구소 1992 農業科學硏究 Vol.10 No.1

This study was carried out far getting reasonable design drought flows which can be contributed to the hydrologic design criterion of various hydraulic structures by comparative analysis between the results of Gumbel-Chew method and those of Weibull distribution which was studied by author already. Annual drought flows were used for the analysis of drought flows frequency at the three watersheds of Geum, Nag Dong and Yeong San river basins. The results were analyzed and summarized as follows. 1. Basic statistics were calculated for the analysis of Gumbel-Chow methed. 2. The frequency factors according to the return periods were evaluated to get probable drought flows for the research watersheds. 3. Probalble drought flows were derivated by the Gumbel-Chow method. 4. Comparing Gumbel-Chow method with Weibull distribution, it was found out that the former haute larger values than these of the latter within five years of return periods, and vice versa over the years of return periods at the research watersheds. 5. In comparison with the observed and the two kinds of results, probable drought flows by Weibull method were shown to be closer to the observed than

鑄物砂의 粒度分布에 따른 通氣度 및 壓縮强度에 관한 硏究

李鍾赫 忠州大學校 1999 한국교통대학교 논문집 Vol.34 No.1

I have obtaind by experiment and books as a following result 1. The sample D has obtained the average 83.65 valve in the air vent grade and so it was superior normal state as second number. I have decision that grain size and air vent grade has a close conneation 2. Casting Sand C has superior normal state in the air vent grade and D has obtained superior result in the compressive strength. 3. The experiment result in the compressive strength and the air vent grade has appeared the same condition, So I have known function relationship according as special mixins with exponential mesh through experiment.

종합병원 입원 환자에서의 불면증의 임상적 특징

이종국,유태혁,한창환 大韓神經精神醫學會 1991 신경정신의학 Vol.30 No.1

The purpose of this study is to investigate the clinical characteristics of insomnia in 300 new inpatients of general hospital with semistructured interview and questionaires. Among 4 clinical groups-129 noninsomniacs, 171 insomniacs (100 insomniacs with past insomnia history and 71 without past history), we compared the following variables ; age, sex, associated significant diseases, usual life habits, environmental variables influencing sleep pattern, types of insomnia, causes of insomnia, coping methods with insomnia, and usage of hypnotics. In insomniacs we also compared the changes of types and causes of insomnia, coping methods with insomnia after admission. The prevalence of insomnia was significantly increased after admission, and was higher in female patients but not significantly different in age. The frequencies of associated significant disease(angina, arrhythmia, asthma, duodenal ulcer etc.), naps, smoking, alcohol and coffee drinking showed no difference between insomniacs and noninsomniacs. Among environmental variables, “apprehension about illness”, “noise”, “nurse's visit”, and “bed discomfort”were significantly more frequent in insomniacs. Presence or absence of past insomnia history gave no significant effect on the types, causes of insomnia and coping methods with insomnia. Difficulty in maintaining sleep(DMS) was significantly increased after admission but difficulty in falling asleep(DFA) was decreased. The causes of insomnia were physical illness, sleep environmental variables, and psychological variables in order ; first two of these were significantly increased after admission. After admission as well as before admission, the most coping method with insomnia was “effort to forget problems”. Among the methods, “exercise or walking” was significantly increased after admission. Afterwards the study on the psychopathology and characteristics of personality which related with insomnia will be needed to broaden our understanding about insomnia and to establish proper management plan of insomnia.

變煥法에 의한 設計渴水量의 誘導

李淳赫,朴鐘國,孟昇辰 충북대학교 농업과학기술연구소 1994 農業科學硏究 Vol.11 No.2

Derivation of reasonable design low flows was attempted by comparative analysis of design low flows derived by Power and SMEMAX transformations for the normalization of skewed distribution in the four watershed of main river basins in Korea. The results were analyzed and summarized as follows. 1. Basic statistics of annual low flows for the selected watersheds were calculated by using Power and SMEMAX transformations. 2. Power transformation has found to be the best for the normalization of skewed distribution among others including Log, Squareroot and SMEMAX transformations. 3. Design low flows for the seleted watershed were derived by the Power and SMEMAX transformations. 4. Judging by the relative suitablities for the Power and SMEMAX transformations, it was found that design low flows using two methods are closer to the observed data within 10 years of the return period, and those of Power transformation can be acknowledged as a reasonable one in comparison with SMEMAX transformation over 10 years of the return period.

복합 적층 박판의 열응력 파손에 대한 진동 활용 비파괴평가

이성혁,이정기,최낙삼 韓國非破壞檢査學會 1999 한국비파괴검사학회지 Vol.19 No.5

두께 1mm의 얇은 복합적층판의 자유경계단부에서 열응력으로 인해 발생하는 미세손상을 진동거동과 관련된 비파괴평가의 가능성을 연구하였다. 유한요소 열응력해석을 통해 예상되는 손상발생영역을 초음파 C-스캔과 광학현미경을 이용하여 관찰하였다. 사인 스윕시험을 이용한 적층보 시험편의 횡진동 해석결과, 미세한 내부손상으로 인해 고유주파수가 확실히 감소하였으며 감쇠비도 상당히 증가하였다. 길이가 짧은 적층보 시험편과 2차 모드의 공진주파수를 이용하여 얇은 적층판에서 열응력으로 유기된 미세손상을 매우 민감하게 평가할 수 있음을 알았다. A feasibility investigation on vibration-based nondestructive evaluation of thermal stress-induced micro failure in the free edge region of thin composite laminates(1mm thick) has been carried out. The failure occurrence and damage zone, which were predicted by the three-dimensional finite-element thermal stress analysis, were observed using the ultrasonic C-scan and optical microscopy. Analysis of the vibration spectrum measured from the laminate beam specimens by the vibration sweep test exhibited that the obvious decrease in resonancy frequency and some considerable increase in damping factor were associated with the micro-failure formation. The vibration technique utilizing short beam and high resonant frequency was found to be very sensitive to the thermal stress-induced damage in the thin laminates.

"半圓形 Notch를 가진 低炭素鋼의 破壞擧動에 關한 硏究"

李鍾赫 忠州大學校 1989 한국교통대학교 논문집 Vol.23 No.-

Resulting from fatigue breaking behavier in use of structure and mechanics by mechanical industry thesedays, the economic loss to result from crack occurrence has been brought about too much loss of lives. In this paper, for the sake of the point at issue solution I have studied on the absorption energy at cracking occurance, stress enlarge coefficient K₁, enlongation quantity by early deformation and maximum load and elongation in the process of generating plastic deformation to which material break resulting from tensile load at the test piece with half round notch.

一般齒車와 周速式 減速機에 대한 考찰

李鍾赫,安樂善 忠州大學校 1996 한국교통대학교 논문집 Vol.31 No.1

In this paper, I have studied on the harmonic drive compared with actual profile. I have obtained the result as follows:The analysis carried out in a plane mechanism. From the analysis of the motion of the rigid gear and the flexible gear, the shapes of the rolling contact plates which move together with each tooth are derived, assuming that the toohh of the flexible gear is rigid although the tooth groove is flexible and that the pitch if the tiith on the unstrechable neutral line of the flexible gear is contact. 1. Harmonic drive could obtain high speed ratio, high torque capacity and high reduction ratio. 2. Harmonic drive has largely used as a gool gearingtooth form. 3. We can obtain a good proper shift coefficiented by strength analysis.

급성 심근경색증을 동반한 혈전성 혈소판 감소성 자반증 1예

이태희,김진혁,김완중,박지영,강흥선,조정휘,김권삼,송정상,배종화 대한순환기학회 2003 Korean Circulation Journal Vol.33 No.11

U-Notch를 가진 鋼板의 機械的 性質에 關한 硏究

李鍾赫 忠州大學校 1987 한국교통대학교 논문집 Vol.20 No.2

In this paper, I have made an experiment in tension tester by changing the notch depth into three types with SM 15C test pieces. I have made cutting work to the depth of 2㎜, 3㎜, and 4㎜ for U-notchs at the testing materials, the width of 1.2㎜, 1.6㎜ and 2.0㎜ U-nochs at thous which the radius of curvature of the edge changed into three kind of 0.6㎜, 0.8㎜, and 1.0㎜. I have got the following conclusion as a result of the tension testing materials. 1. As the depth of U-notchis fixed and only the width for U-notchs and radius of curvature changed, the stree by means of the notch effedt came out largely. 2. At the part of notch, the sensitiveness of coefficient for notch came out larger than the one (1) by plastic deformation in all. 3. At the part of notch, if the radius curvature changed, the testing pieces was yielded at the notch by stress concentration. As absorbing energy among plastic deformation, a decrease phenomenon came out.