機械加工品의 最適加工速度에 關한 硏究

成煥泰,吳澤烈,吳煥燮 慶熙大學校 1980 論文集 Vol.10 No.-

In this study, the optimum mathematical models were made in order to derive Optimum Machining speed which is due to be established in the production of each manufactures as an important parameter based upon the cutting speed, in case of making manufactures of multi-kinds into unit-production processing. The economical optimum cutting speed has been set up by using the above phenomenon as a proper system, and the results from the comparative analysis between the above model & the actual cutting work data, are summarized as follows. (1) The mathematical models for the optimum machining speed are derived into the expressions (23), (24), (25), (26), (27), (28), (29). (2) The basic expressions of the optimum machining speed are derived into (32), (34), (36), (37), (39), (40), (41), (44), for the purpose of each estimation of the maximum efficiency standard, the minimum cost standard and the maximum profits rate standard. (3) The example of setting up the optimum cutting speed of multi-kinds manufacturing production was formulated, and the experimental theoretical values were known to be in the same range as a result of the comparative study between the cutting speed obtained by the cutting test & the optimum cutting speed calculated by the theoretical expressions.

五成貯水池의 富營養化 豫測에 關한 硏究

金煥起,朴相肅,申殷燮 全北大學校 附設 都市및環境硏究所 1994 都市 및 環境硏究 Vol.9 No.1

This study was performed in order to estimate the eutrophic potentials in Oseung Reservoir, located on Jeong-eup in Chonbuk. The experiment was carried out to expect the eutrophication by nitrogen and phosphorus inleted collection-area after Dam construction. The obtained results are as follows; 1. According to water quality analysis, 3.6∼4.7㎎/ℓ of COD appeared to the much biological nondegradation organic even though BOD 0.4∼1.1㎎/ℓ. 2. The expected water quality of Oseong will attach BOD 0.8㎎/ℓ, COD 4.09㎎/ℓ, T-N 6.67㎎/ℓ and T-P 0.034㎎/ℓ. 3. The restrain function of the reservoir is T-P according to the criteria of eutrophication. 4. After Dam construction, KSTI 48.5 produced from T-P will be graded in the middle condition. Therefore, the good counter measure is expected to prepare.

中空丸奉材의 疲擧크랙擧動에 關한 硏究

吳煥燮 慶熙大學校 1980 論文集 Vol.10 No.-

The characteristic of the crack propagation behavior, crack growth rates and stress intensity factor under the rotary bending fatigue test have been studied. The equation dealing with fatigue crack propagation velocity and stress intensity factor based on this study has been confirmed in the test of cylindrical shell specimens having small-scale hole notch. In this study, the effects of stress gradient along with the bending by limitation of specimen to 1mm in thickness are not easily distinguishable to confirm the stress intensity factor and fatigue crack growth rates of specimen surfaces. Also, cylindrical one is just the same as in case of the round plane shaped by formming itself, so on the endless plane, the effect of cylindrical carvature and hole about the correction factor are considered respectively. Therefore, the equation of stress intensity factor is determined by K=k_1k_2σ√πℓ The stress intensity factor K concerned with dl/dN has been plotted in log-log diagrams, and here material constant C is obtained after order m is calculated.

疲勞크랙의 發生 및 傳播擧動에 對하여 : 素面크랙을 中心으로 Through Surface Crack

吳煥燮 慶熙大學校 1982 論文集 Vol.11 No.-

In recent days, there are many reports about fatigue crack behavior mostly connected with reciprocal relations combined crack propagation velocity and stress intensity factor. And applications of fracture mechanics of macro crack have been generalized, but analysis of the mechanics of micro crack which are contained in steel structures have very some important problems as follows; in case that fatigue cracks would be initiate and propagate in the region of interstitial compound and micro notch, the fatigue crack progress symmetry and the fatigue crack growth propagation velocity round the compound under same repeated stress cycle each other. In this paper, a rotary bending fatigue test was done with micro hole notched specimen of rolled low carbon steel, and then the crack initiation behavior on the crack tip, propagation behavior of front and rear of the crack and latency phenomenon during the crack propagation process, is present.

안와를 침범한 상악동 악성종양에서 안구 보존을 위한 내시경의 역할

조규섭,노환중 부산대학교 병원 암연구소 2008 부산대병원학술지 Vol.- No.24

Background and Objectives: The periorbita has been regarded as the crucial structure in decision of orbital exenteration in the patients with paranasal malignancies. The mass beyond the thickened periorbita on T2-weighted images was considered to be a positive finding of orbital invasion. The purpose of this study is to evaluate the oncological safety of endoscopic removal of infiltrated tumor onto the periorbita but not transgress into orbital fat. Patients and Methods: Five patients of advanced maxillary cancer, showing bony orbital wall destruction and infiltration onto the periorbita but not transgress into orbital fat, underwent partial or total maxillectomy. Preoperative Cl and MRI were performed in all cases and compared with intraoperative findings. The successful dissection between tumors and periorbita using bipolar nasal coagulation forceps and tumor forcep was performed under endoscopy. Results: The mean age was 54.4 (41-74) years. All tumors of five patients originated from maxillary sinus and extended to involve multiple different subsites according to AJCC (2002, 6^(th) ed.) Histopathology included four squamous cell carcinomas and one adenoid cystic carcinoma. Follow-up ranged from 30 to 121 months (mean 53.6 months). All cases showed no local recurrence on the periobita after endoscopic removal. One patient had local recurrence in the pterygopalatine fossa and the other had in the neck. Conclusion: Endoscopic removal of infiltrated tumor onto the periorbita using microdebrider, bipolar nasal coagulation forceps and tumor forceps can be oncologically safe technique in advanced maxillary cancer infiltrated onto the periorbita but not invaded into orbital fat.

人工缺陷을 갖는 炭素鋼材의 微小疲勞크랙擧動

吳煥燮 慶熙大學校 材料科學技術硏究所 1989 材料科學技術硏究論集 Vol.2 No.-

This study has been made to investigate into the behavior of fatigue crack propagation under the condition of rotating bending stress. The results obtained can be summarized as follow; In the case of single surface defect, fatigue crack produce semi-elliptical crack contour which has the ratio of crack length in the radial direction to the half crack length on the surface at 0.85 in the neighbored double surface defect, the behavior of fatigue crack propagation has the effect of delay as well as the interference effect. In the view of small crack propagation rate (da/dN), the size of single surface defect depends upon stress intensity factor (k)

이종마찰압접재 계면의 기계·금속조직학적 거동 및 파면특성 : STS304와 SM15C재를 중심으로 For STS304 and SM15C

오환섭,박경식,박준건,오정국,백영남 慶熙大學校 材料科學技術硏究所 1998 材料科學技術硏究論集 Vol.11 No.-

In this study is behavior of crack propagation and fracture under static tensile load, shear load, rotary bending fatigue load in friction welded dissimilar materials. Crack was observed in fine ferrite zone of SM15C and heat affected zone of STS304. Plastic flow was occured by friction welding process, so direction of crack is inclined with welded surface. Fatigue fracture most occurred in SM15C heat affected zone around interface. Fibrous zone with the view of macroscope and dimple pattern with the view of microscope were observed at fracture surface. Result is more metal micrstructure dependence than stress dependence by mechanical and metallic mechanics.

이종재 브레이징 계면에서의 균열거동 해석

오환섭,김시현,김성재,양인수 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.6

Applications of brazing in the studying fields such as high-speed machining are very increasing in various industry fields. Therefore, applying to the fracture mechanics by numerical analysis method is very important to analyse the crack problem dissimilar materials in brazed interface. In this study, stress intensity factor(SIF) is analysed to investigate crack behavior on the crack tip of dissimilar materials in brazed interface such as a hardmetal and a HSS by two dimensional(2-D) BEM. Kelvin's solution was used as a fundamental solution in BEM analysis and stress extrapolation method was used to determine SIF.

압력용기의 설계기준 및 손상 평가

오환섭,정효진,박상필,손두익 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-

The damage of the pressure courage by degradation can become the reason of unexpected break down or failure accident and it is very important because safety accident, the production loss, environmental pollution, social problems are occur. Consequently The result to investigat of failure accident for domestic pressure vessel, the factor of degradation is SCC, Sorrosion, Cavity, Crack

表面微小缺陷을 갖는 低炭素鋼材의 疲勞限度擧動

吳煥燮 慶熙大學校 1986 論文集 Vol.15 No.-

Low-carbon steel was chosen as the material for this experiment since it has clear fatigue limit as well as the reason that the defect in the structure of the material does'nt effect to the fatigue fracture. This study has been made to investigate into the behavior of fatigue limit, of fatigue crack initiation, and of fatigue crack propagation under the condition ol rotating bending stress; specifically on the independency of stress-field as well as the crack behavior of surface micro-hole defect(MHD), which it made artificially the specimen. The results obtained can be summarized as follow; Fatigue limit of specimen with MHD is defined as a critical stress which is needed for repropagation of the crack around MHD. The behavior of non-propagating crack which is positioned around the MHD is found to be double of the size of MHD. The effect of MHD with regard to the fatigue limit and size of critical defect(dc) are depended on hardness and ferrite grain size.