SFA55材의 機械的性質 및 비틀림疲勞特性에 미치는 熱處理溫度의 影響

吳世旭,金晋坤,朴正洙 동아대학교 공과대학 부설 한국자원개발연구소 1984 硏究報告 Vol.8 No.2

Nowadays, SFA55 has been used to train frame widely It is necessary that mechanical properties and fracture behavior of SFA55 should be evidently cleared in order to prevent fracture accident of train frame previously. For impact test specimens SFA55 have been treatted by two methods; water-quenched at 880℃, tempered at various temperatures, and for twisting fatigue test specimens; normalized at 880℃, tempered at 550℃ after quenched at 880℃. Impact test has been performed by charpy impact tester (30Kgf-m) and twisting test has been conducted by schenk type twisting tester. After tests, fracture behaviors and effects of heat treatments have been investigated with Scanning Electron Microscope. The main results obtained were as follows; 1) Impact values of SFA55 have increased, but hardnesses have decreased with the tempering-temperature increasing. That is, ductility has been increased. 2) It has been generally reported that the difference of fatigue limits between normalized materials and quenched-tempered materials was almost negligible, but it has been observed that the fatigue limit of the later was greater than that of the former. 3) In the impact test specimen, the fractured surface at vicinity of U-notch was ductile dimple style and at nearly center area was brittle cleavage fracture. 4) At the center area of the impact test specimen the dimple style has been increased with the tempering temperature. 5) The normalized materials of the twisting fatigue test specimen has smooth and clean striations but the quenched-tempered materials has discontinuous and irregular striation.

와동형태의 설계에 따라 치아에 발생되는 응력의 변화에 관한 연구 : 인레이의 경우

오세윤,김웅철,김지환,유진호 高麗大學校 倂設 保健大學 保健科學硏究所 1995 保建科學硏究論集 Vol.4 No.1

Because of the anatomical form of posterior teeth, the amount of tooth reduction near the marginal ridge area in the typical, widely used intracoronal cavity will be inevitably maximal, while occlusal forces on the restoration in this area will be relatively minimal In an attempt to dicrease the amount of tooth reduction at the marginal ridge area, a modified cavity for inlay with a uniform depth of 15mm, just as in amalgam filling was designed in this study. To analize the stress development in the teeth in that cavity design, 2㎏/㎟ distributive forces were applied on the inlay restoratives and obtained results were compared with that in the typical cavity design which had a flat pulpal wall with a depth of 1.5m at the central fossa area. Analysis was done with two dimensional finite technique. The obtained results were as follows : 1. The patterns of stress distribution and displacement showed no apparent differences. 2. The stress values and the amount of displacement developed, both in inlay cast gold and in the teeth, in the cavity with a uniform depth were less than that in the cavity with a flat pulpal wall. 3. Greatest maximum principle values were concentrated around the interface between the base of inlay body and the teeth.

SUS 316L의 콘크리트强度 및 破壞擧動에 미치는 結晶粒度와 溫度의 影響

吳世旭,金晉坤 東亞大學校 1983 東亞論叢 Vol.20 No.3

SUS316L have been dealed with the solution treatment for 1hour, 5hour and 10 hour at 1100。C respectively, thus have been obtained grain size of ASTM number 6,5 and 4 and then conducted by creep test on the uniaxial state of strss. The effect of grain size on the creep strength and fracture behiviour of SUS316L have been investgated at the different temperatures(600。C) and the different stresses separately. Failure surface have been observed by scanning electric microscope. The main results obtained were as follows. 1. The optimum grain diameter for the maximum creep strength is hardly influnced by the change of stress but depends upon the temperature heavily. 2. The initial strain increase when the grain is coarsenned or the creep test temperature is raised. 3. The equation of rupture life, ?? was applied to the SUS316L well. 4. The SUS 316L of low carbon is only observed as the failure surface (thought of similar intergranular) but shown the behavior of ductile because of equiaxed and elongated dimple. 5. Under the various test temperature the optimum grain diameter is found with the fine and equiaxed dimple at perpendicular and flat fracture surface but is prevalently shown elongated dimple at the other grain diameter.

악안면 골격 형태에 따른 교합평면각의 변화에 관한 두부 방사선학적 연구

오세윤,김웅철,김지환,이준석,김진완,유진호,김태석 高麗大學校 倂設 保健大學 保健科學硏究所 1999 保健科學論集 Vol.25 No.1

A correlation analysis was made to understand the interaction between the growth patterns of some craniofacial skeletal components and occlusal plane inclination. 5 angular measurements(S.a. Ar.a, Go.a, UGo.a, LGo.a), 6 linear measurements(ACBL, PCBL, RH. MBL. AFH. PFH) and OP/SN. obtained from 83 cephalometric tracing records, were selected and the relationship between the occlusal plane angle and those measurements were analyzed statistically. Ramus Height(r=-0.55), Posterior Facial Height(r=-0.41), were found to be negatively related with Occlusal Plane angle, while Lower Gonial angle(r= 0.35), Saddle angle(r= 0.24) were found to be positively related with Occlusal Plane angle(p(0.05). The results obtained from the above analysis were further assessed with stepwise regression analysis, using Occlusal Plane angle as a dependant variable, and RH, LGo.a and S.a as explanatory variables. Stepwise regression analysis revealed that all the explanatory variables were found to be significant.(p<0.05) [OP/SN] = -8.74-0.33(RH)+0.23(S.a)+0.20(LGo.a). (R²=0.44). This stepwise regression analysis explains, to some extent, the relationship between the growth patterns of some craniofacial skeletal components and the occlusal plane inclination. 1. The inclination of Occlusal Plane angle is noticeably related with the growth patterns of some craniofacial skeletal components, i.e. RH, PFH, Saddle angle and Lower Gonial angle 2. In high Occlusal Plane angle, the Ram us Height tends to be shorter, and the Saddle angle and Lower Gonial angle tend to be obtuse.

대학 스포츠 종목별 우수선수들의 신체조성에 관한 연구 : 第1報-種目別 身體組成 測定 結果

성동진,오세진,최태석,송홍선 韓國體育大學校附屬 體育科學硏究所 1997 韓國體育大學校附屬 體育科學硏究所論文集 Vol.16 No.1

The purpose of this study was to investigate the characteristics of Body composition for K University elite Athletes. The total subjects were 458 athletes(331 male athletes, 127 female athletes). The results was as fellowing 1. Average triceps thickness, male was 9.59mm and female was 20.20mm. 2. Average subscapula thickness, male was 11.17mm and female was 14.08mm. 3. Average %Fat, male was 14.05% and female was 23.57%. 4. Average fat mass, male was 10.43kg and female was 14.17kg. 5. Average Lean body mass, male was 61.7kg and female was 44.84kg.

치과 기공사들에게서 나타나는 호흡기 증상과 이의 관련 요인

김웅철,오세윤,김지환,김진완,이준석,이가영,이세훈,유진호,김태석 高麗大學校 倂設 保健大學 保健科學硏究所 2001 保健科學論集 Vol.27 No.1

This study was carried out to investigate subjective respiratory symptoms and their attributable factors in Korean dental laboratory technicians. A questionnaire was mailed to randomly selected 1,900 dental laboratory technicians. Among them, 1,344 dental technicians completed the questionnaires and returmned them. Validity and reliability tests on the questionnaires were carried out before the main survey. To investigate risk factors on respiratory subjective symptoms, we performed analysis on distribution of characteristics, and then investigated univariate analysis and multiple logistic regression analysis. The prevalence rate of wheezing, cough and phlegm, and dyspnea was 4.8%, 33.9%, 54.9%, respectively. Statistically significant factors inducing subjective respiratory symptoms by multiple logistic regression analysis were sex, smoking, exercise, health examination, work hours a day, investment gas, investment dust, metal fume, resin vapor, and asbestos dust. Considering the results above, it seems that most subjective respiratory symptoms are related with health habits and occupational environmental-related factors. The result, consideration in mind, suggest that health promotion programs for smoking cessation, regular health examination, and physical exercise in health habit, and improvement on casting and resin work in dental technological environment be necessary.

韓牛 肥育促進을 위한 Cobalt(Co) 給與效果에 關한 硏究

尹熙燮,吳世正,姜昌鎭,金時明 건국대학교 1978 學術誌 Vol.22 No.1

For an increase of body weight, feed efficiency, and profitability of Korean cattle fattening through the effective fattening of the Korean cattle concentrates with an addition of 0.05 mg of cobalt for test plot I, 0.05 mg of cobalt for test plot II 0.10 mg, and 0.15 mg for test plot III, per kg of concentrate were given to sampled cattle. Experiments were designed to repeat control plot and three test plots (I, II, III) five times far 140 days on the 20 cattle sampled by completely randomized design. The results of the experiments are presented in the following. I. Amount of Body Weight Gain The average weight gain per head, and weight gain per day are commonly highest in the test plot II (132.6 kg ㆍ 0.92 kg), second in the test plot I (128.5 kg ㆍ 0.91 kg), third in the test plot III (121.1 kg ㆍ 0.87 kg), and lowest in the control plot (120.4 kg ㆍ 0.87 kg). The rull hypothesis was accepted while there was no statistical significance between the test plots and the control plot, and also among the test plots. But the test plots with an addition of cobalt resulted in higher gain of body weigh comparing to that of the control plot. II. Amount of Feed Intake and Feed Effeciency The efficiency of concentrate required to increase on Kilogram of beef was highest in the test plot II 6.42 kg, second in the test plot I 6.53kg, third in the test plot III 7.00 kg, and lowest in the control plot 7.18 kg respectively. In case of flay and pellets the test plot I showed the highest weight gain, the test plot II, and III resulted in the same performance, and the control plot was the lowest one in the gain of body weight. There was no statistical significance between the test plots and control plot, and among the test plots. Thus, the test plots with ail addition of cobalt comparing to the control plot resulted in a higher feed efficiency. III. Profitability Feed costs required to increase one Kilogram of fresh meat was 636 casts won in the test plot II, 641 won in the test plot I, 685 fresh meat won in the test plot III, and 703 won in the control plot respectively. While there was no statistical significance with profitability, the test plot with an addition of cobalt required lower feed cost increase one kilogram if fresh meat comparing to the control plot. IV. Fattening outcome Of the sampled 20 cattle 18 cattle were slaughtered after 6 days from the last day of the tests. The carcass rate of the sloughtered cattle was 56.4 percent in the test plot II, 55.0 percent in the test I, 54.8 percent in the test plot III, and 54.6 percent in the control plot. There was no statistical significance with the rate of carcass, but the test plats with an addition to cobalt presented a little higher carcass rate comparing to the control plot. It was rather difficult to distinguish meat color with eyes, but comparing to the control plot the meat color of the test plots was heavily red.

Ti-Ni 형상기억합금의 변형특성에 미치는 pre-strain의 효과

조용배,오세욱,김득진,박영철 東亞大學校 海洋資源硏究所 1994 硏究論文集 Vol.7 No.1

In SMA(Shape Memory Alloy), the degradation by fatigue is one of the most important problems to be overcome, when SMA is used for robot-actuator materials. The acuator is operated repetitively for long time and its repeating operation develops the fatigue degradation of SMA. The fatigue degradation changes the transformation temperature and deformation behavior and results in inaccurate operation control of robot. Accordingly, the changing behavior of transformation temperature and deformation which results from repeating operation is to be investigated in advance and the scheme to resolve those problems have to be made for the design of actuator. In this paper, for the improvement of the fatigue degradation by repetive movement and better control of the correct movement by the stability of martensite transformation in the developement of Robots actuator, Pre-strain(0, 1.5, 5, 8%)were loaded in the specimens and fatigue testing were carried out by the method of heating and cooling in direct condition. From the results of these experiments, the effects on pre-strain which affect the transformation characteristic and fatigue degradation phenomena were correctly investigated

단거리 선수의 수행수준 차이에 따른 생리학적 변인의 특성

정연수,오세진 韓國體育大學校附屬 體育科學硏究所 1996 韓國體育大學校附屬 體育科學硏究所論文集 Vol.15 No.1

The purpose of this study was to compare physiological characteristics of three different levels of 100m female sprints. the 30 subjects in this study were assigned, according to their 100m running time, to one of three different group: fast, average, slow. All subjects were tested for performance in the Wingate anaerobic test, strength, fat %, reaction time, flexibility, aerobic power. The data was analyzed by one-way ANOVA with post-hoc Turkey test, which was performed on each variable to find difference between the groups. The ANOVA indicated significient differences among all three groups for performance in the Wingate anaerobic test and relative strength. The dofferences in reaction time were significient only between thr fast and the average groups. Significient and negative correlation were found between thew 100m running time, relative strength, and performance in the Wingate anaerobic test. Significient and pogitive correlation were found between running time, % fat. No significient correlation were found between running time and peak ?? reaction time and fiexibility. Stepwise regression analysis indicated that the combination of performance in the Wingate anaerobic test and strength providedthe most efficient(r=0.92) prediction of 100m run times. This study demonstrated that the main difference among female sprinters of different performance levels lies in their ability to, produce muscular power, strength.

Neuropathic Pain의 동물모델에서 유발된 Thermal Hyperalgesia에 대한 Clonidine의 효과

윤석화,오세철,최세진 충남대학교 의과대학 지역사회의학연구소 1993 충남의대잡지 Vol.20 No.2

The effects of intraperitoneal injection(i.p.) of the alpha 2 adrenal receptive agonist, clonidine on the thermal hyperalgesia produced by unilateral patially tight ligation of the sciatic nerve was studied in rats. First in the preoperative and postoperative Mays, paw withdrawal latency of both hind paw(lesioned,unlesioned) with heat stimulant was tested. After that, each groups of rats injected saline, clonidine 10㎍/kg, or clonidine 50㎍/kg. I.p.10㎍/kg and 50㎍/kg clonidine, paw withdrawal latency of lesioned side significantly reduced than saline group. It is suggested systemical clonidine may be useful in treating neuropathic pain in humans.