알루미나이징 表面處理한 構造用鋼의 彼勞强度 및 破壞擧動에 관한 硏究

吳世旭,朴春根,全泰玉,全哲昊,周原植,李圭用 東亞大學校 大學院 1978 大學院論文集 Vol.2 No.-

Aluminizing-treated structural steel is excellent in high temperature oxidation resistance, wear resistance and corrosion resistance. So, it has been widely used for the machine parts which have required such properties. However it is difficult to find out any study result of the notched influence on the aluminizing-treated materials and the second diffusion materials. In this investigation the low carbon steel plates with with V-notches were coated with aluminum and made into second diffusion. With these specimcns the bending fatigue strength and fatigue life were observed and also crack propagation of alloy layer was investigated. The results obtained are as follows: 1) On the smoothed specimens a fatigue limit of aluminizing material was lower than the one of raw material, but it was more increased than the one of heat treatment material, and the fatigue limit of second diffusion material was lowest. 2) On the V-notched specimens a fatigue limit of aluminizing material was higher with 44% increase ratio than the one of raw material and with 63% increase ratio than the one of heat treatment material, and the rate of increase became lower increase ratio in a fatigue limit comparing to aluminzing material, with no influence of notch radius. 3) According as the notch radius became smaller, the fatigue limit became. higher on the raw material, it was same on th aluminizing material and lowest on the second diffusion material. 4) Crack initiation period was 0.04% below of fatigue crack life and the full growth period of crack propagation at alloy layer was 0.1%. The crack propagation from alloy layer to matrix was 16% of the fatigue crack life. This means that the crack propagation rate at alloy layer was very fast but the crack delay at the boundary of both was so long. 5) Crack propagation grows through defects, inclusion, peeling and previous boundary.

FESWMS-2DH를 이용한 하천의 흐름 해석

이철응,심재욱,박동헌 江原大學校 産業技術硏究所 2009 産業技術硏究 Vol.29 No.A

In this study, flood stage was computed by HEC-RAS, 1-D numerical analysis model and FESWMS-2DH, 2-D numerical model. Flood stages computed by two different models were compared for straight line, dot axle watercourse, dead-zone watercourse, section sudden-changing watercourse, and curved watercourse. From the results, flow velocity and water level were similar in straight watercourse and dot-reduction watercourse. However, there was difference of flow velocity and water level in dead-zone watercourse, sudden expansion, dot-reduction, and curve-watercourse. This result might be influenced by rapid change of watercourse due to dead-zone, the angle of inflow and outflow, and the curvature. Especially in this study, numerical model was applied to Wol-Song-Cheon at Chuncheon in order to analyze the effect of flood stage by two different models. By flowing properties around the bridge and confluence of rivers, it was found that flow velocity and water level was changed. Therefore, it was concluded that a lot of uncertainties are contained in the present bank.

컴퓨터 단말기 업무자의 요통의 위험요인에 관한 연구

이철호,박정래,차애리,고광욱,김영욱,이수일 大韓産業醫學會 1999 대한직업환경의학회지 Vol.11 No.2

Low back pain in computer terminal operators is a very common but important symptom. While the occupational risk factors of low back pain were approved obscurely, there have been few studies on analysis or understanding of occupational risk factors. Therefore, we studied occupational risk factors of low back pain, especially for ergonomic factors as well as general characteristics of workers. We selected 98 subjects for this study, computer terminal operators ordinary using computers in Pusan. We calculated the subjective severity of low back pain of each operator by the Low Back Pain Scoring System. The relation of low back pain score to general characteristics of worker was also analyzed. We analyzed the relationship between low back pain score and individual efforts to prevent low back pain. We measured the ergonomic factors of each computer terminal operator-Trunk Inclination(TI), Arm Flexion(AF), Elbow Angle(EA), Head Tilting(HT), Knee Angle(KA), using of foot plate and gap between the popliteum and chair. The correlations between these ergonomic factors and low back pain score were then analyzed. And the results are as follows: 1. The prevalence rate of low back pain in computer terminal operators was 39.8% in this study, when low back pain score was converted by the low back pain scoring system. 2. According to general characteristics of workers related to low back pain, the scores were higher in the older age group, the married and the longer work carriers.(p<0.05) 3. In the analysis of the relationship between low back pain score and individual effort to prevent low back pain, regular exercise, history of schooling for prevention of low back pain, and declaration of intention to participate in low back pain education or exercise were stastistically significant(p<0.05). And the more severe the low back pain, the higher the intention to participate in low back pain education they had in this study. 4. In the analyses of relationships or correlations between low back pain score and each of the 7 categories of ergonomic factors, only head tilting had a weak reverse correlation with low back pain(r=0.2999, p<0.01). From now on, cohort studies for the risk factors of low back pain of workers, who have been forced to work in non-ergonomical positioning at the work site, will be necessary. On the background of these ergonomic studies, the occupational health profession should be required to manage ergonomic working conditions.

임시 금관용 비귀금속 합금의 전기화학적 부식에 관한 연구

김정욱,임범순,김철위 서울대학교 치과대학 치과생체재료학교실 1994 치과생체재료학 논문집 Vol.2 No.1

The employment of base metal alloys as substitutes of gold alloys is gaining increasing popularity. The corrosion of dental base metal alloys was recoginzed due to the nature of the oral environment. Corrosion of dental meterials in the mouth can affect the mechanical properties, esthetic properties and efficiency of dental metallic restorations, and has great influence upon the local and systemic health of the patient. The researches on the harmful effect of dental base metal alloys and their corrosin products on the human body are progressed actively. The electrochemical corrosion studies in vitro were done to predict the corrosion behavior of dental alloys in vivo, but the result may be different depending on the corrosion environments. As the normal range of inorganic ions and organic molecules in saliva is various with patient, in vivo corrosion behavior may be different depending on the patients. It may result in interindividual differences on corrosion behavior even though the restorations were made of the same alloy. The purpose of this experiment was to evaluate the difference in corrosion behavior of dental base metal alloys for temporay crown when the concentrations of organic compounds in the artificial saliva were varied. The materials used in this study were the modified Fusayma's artificial saliva (pH. 6.7), and the artificial saliva with organic compound additions such as polyacrylic (5㎖/1), acetic (5㎖/1), citric (2 g/l) and lactic acid (5㎖/1). Totalof four kinds of dental base metal alloys for temporary crown; two kinds of stainless stel alloys (SSP: 17% Cr-12% Ni-67% Fe, INC : 17% Cr-9% Ni-68% Fe), nickel-chromium alloys (APC : 90% Ni-5.5% Ni-4.5% Cu), and aluminium alloys (APC : 99% Al-0.5% Fe-0.1% Cu), were studied. Specimens were 0.2㎜ thick and had surface area of 1 ㎠ (or 0.25㎠). The specimens were connected to the copper wire and mounted in the self-curing acrylic resin. Embedded specimens were polished with the silicon caarbide papers up to # 2,000, then ultrasonically cleaned, and dried by clean air. After the surface oxide layer of specimens was removed at-1,500㎷(SCE) immersed in the vairous meterials, the corrosion behaviors of the specimens were studied by electrochemical hysteresis technique involving potentiodynamic polarization from - 1,000 ㎷ to + 1,000 ㎷ and reverse polarization back to -1,000 ㎷ with the scanning rate of 2㎷/sec in the aeration environment. The current density change of specimen was recorded X-Y poltter via logarithmic onverter. From the experiment, the following results werre obtained : 1. For the stainless steel specimen SSP, passivation film was formed in the artificial saliva and in the artificial saliva with organic components added electrolytes. SSp showed the good corrosion resistance in experimental electrolytes. Addition of organic components to the artificial saliva showed only minor effect. 2. The formation of passivation film on INC was unstable. It was observed that the corrosion resistance on INC was lower than that of SSP. 3. In the nickel-chromium alloys specimen APC, the possibility of passivation film formation was lower than in the stainless steel specimens SSP and INC. It causes lower corrosion resistance than that of SSP and INC. 4. In the aluminium alloys specimen, ATP, showed the dissolution reaction in all experimental electrolyes such as artificial saliva and artificial saliva with polyacrylic, acetic, citric, and lactic acid added.

두부 상하위가 운동후 회복기 심박수 및 혈압에 미치는 효과

한창욱,김형진,김철진 慶北大學校 醫科大學 1997 慶北醫大誌 Vol.38 No.1

목적 : 두부 상하위가 운동후 회복기 심혈관계 조절에 미치는 효과를 구명하고자 하였다. 대상 및 방법 : 20-23세 남자 대학생 31명을 대상으로 하여 3분간의 rebounder 운동을 실시한 후 15도의 두부상위, 15도의 두부하위 또는 앙와위에서 20분간 회복 중 심박수, 혈압 및 호흡수의 변화를 측정하였다. 대상자는 운동을 하지 않고 두부상위 (U, 6명) 또는 두부하위 (D, 6명)를 취한군과 운동후 두부상위 (EU, 7명), 두부하위 (ED, 6명) 또는 앙와위 (ES, 6명)를 취한 군으로 나누었다. 결과 : U 및 D군에서는 심박수, 혈압 및 호흡수에 유의한 변화가 없었다. EU군에서 운동후 1분에 심박수, 수축기 혈압 및 호흡수는 각각 109.2±17.9 beats/min, 168.3±7.6 mmHg 및 27.3±1.9 breaths/min로서 비운동군에 비해서는 유의하게 높았으나, 심박수는 안정시에 비해 유의한 증가를 보이지 않았고, 회복기 5분 이후 평균동맥압은 안정시 및 비운동군에 비해 낮은 경향을 보였다. ED군에서 운동후 1분에 심박수, 수축기 혈압 및 호흡수는 117.4±7.7 beats/min, 155.0±13.4mmHg 및 33.2±1.4 breaths/min로서 비운동군에 비해서는 유의하게 높았으나, 회복기 1 및 5분의 수축기 혈압은 ES 군에 비해 유의하게 낮았고, 평균동맥압은 회복기 1∼3분 동안 불안정하였고 5∼15분 사이에는 계속 감소하는 경향을 보였다. 결론 : 이상의 결과로 볼 때 운동후 회복기에 두부상위 자세는 동맥압 조절능력을 약화시키며 두부하위 자세는 동맥압 조절기전을 불안정하게 하는 것으로 생각된다. In an effort to elucidate the effect of head-up and down tilt on the cardiovascular regulation during recovery period after exercise, 31 healthy male college students aged between 20-23 yr were employed to exercise on a rebounder for 3 min and to take 15° head-up tilt, 15° head-down tilt or supine position for 20min during which heart rate, blood pressure and respiratory rate were measured. The subjects were divided into 5 groups: head-up tilt without exercise (U, n=6), head-down tilt without exercise (D, n=6), head-up tilt after exercise (EU, n=7), head-down tilt after exercise (ED, n=6), supine position after exercise (ES, n=6). Heart rate and respiratory rate were measured from an electrocardiogram and pneumogram recored with a physiograph. Blood pressure was measured with a mercury sphygmomanometer. 1. In non-exercise groups (U, D), there were no significant change in heart rate, blood pressure and respiratory rate. 2. During head-up tilt after exercise (EU), heart rate, systolic pressure and respiratory rate at 1 min were 109.2 ± 17.9 beats/min, 168.3 ± 7.6 ㎜Hg and 27.3 ± 1.9 breaths/min, respectively, which were significantly higher than in the non-exercise group (U). Heart rate did not show a significant increase compared with rest. Mean arterial pressure at 5 min and thereafter tended to be lower than at rest or in the non-exercise group. 3. During head-down tilt after exercise (ED), heart rate, systolic pressure and respiratory rate at 1 min were 117.4 ± 7.7 beats/min, 155.0 ± 13.4 ㎜Hg and 33.2 ± 1.4 breaths/min, respectively, which "were5 significantly higher than in the non-exercise group (D). Systolic pressure at 1 and 5 min was significantly lower than in the non-exercise group. Mean arterial pressure was unstable during 1-3 min and tended to progressively decrease during 5-15 min. It was concluded therefore that head-up tilt during recovery period after exercise might compromise the arterial pressure regulation system whereas head-down tilt might render the regulation mechanism unstable.

초탄성과 열역학적 나이티놀 탄선에 관한 고찰

김정욱,김철위 서울대학교 치과대학 치과생체재료학교실 1994 치과생체재료학 논문집 Vol.2 No.1

우울증 선별 검사 도구로서 Beck Depression Inventory(BDI)의 타당성 : Detection of depression in primary care

신호철,김철환,박용우,조비룡,송상욱,윤영호,오상우 大韓家庭醫學會 2000 Korean Journal of Family Medicine Vol.21 No.11

동종골수이식 환자에서 발생한 지역사회발생 Parainfluenza virus 3형 폐렴 1예

신종욱,조요한,강철인,김성한,이상윤,김의석,오명돈,이환종,박선양,김병국,최강원 대한감염학회 2002 감염 Vol.34 No.5

군 훈련병의 스트레스, 성인 주의력결핍 과잉행동장애 증상과 자살사고의 연관성에 관한 연구

이동윤,이철순,박철수,손진욱,김봉조,차보석,이소진 대한생물치료정신의학회 2011 생물치료정신의학 Vol.17 No.2

Objectives:This study is conducted to investigate the effect of Attention Deficit and Hyperactivity Disorder(ADHD) symptoms on stress and suicide idea among 224 conscripts. Methods:Total number of subject is 224 conscripts. We evaluate symptoms of adult ADHD with Korean-Wender Utah rating scale(K-WURS) and Korean adult attention-deficit/hyperactivity disorder scale(K-AADHDS), stress with Brief Encounter Psychosocial Instrument-K(BEPSI-K), suicide idea with Scale for suicide ideation(SSI) after basic military training. Multivariate logistic analysis with backward stepwise selection is performed to evaluate risk factors of stress. Multiple linear regression analysis with stepwise selection is performed to evaluate association of suicide idea with adult ADHD symptoms. Results:Stress is significantly associated with K-WURS score, K-AADHDS score and SSI score(p<0.01, p<0.05, p<0.01). K-WURS score are significant risk factor of stress after basic military training(p<0.05, O.R : 1.034, 95% CI : 1.005-1.065). And K-WURS score influence suicide idea after basic military training(p<0.05, β : 0.031). Conclusion:The result suggests that K-WURS score might be a risk factor of stress and could affect suicide idea.

서울시에서 산발적으로 분리된 Salmonella enterica Serotype Typhi 임상분리균주들의 분자역학적 분석

이희무,김철현,손장욱,김민자,박미선,이복권 대한감염학회 2000 감염 Vol.32 No.5