측면 홈을 가지는 STS316 CT시험편의 정적 성장균열에 대한 프랙탈 기하학의 응용

윤유성,권오헌 한국산업안전학회 2002 한국안전학회지 Vol.17 No.4

The application of fractal concept provides an useful method in the study for the quantitative analysis of irregular variations like fracture surfaces and crack profiles. Fractal curves have characteristics that represents a self-similarity based on the fractal dimension. The fractal dimensions were obtained by the box counting method. In this report, we obtained the nearly stable fractal dimensions of fracture crack profiles for STS316 with CT specimens as the crack advances and the relationships between crack length and fractal dimension. Moreover fractal fracture parameter that corresponds to J-R curve is shown by the relationships between fractal dimension and crack extension. From the results, we concluded that the crack extension of high toughness material also shows the fractal characteristics, which can be used in order to evaluate the crack life precisely.

레이저를 이용한 Tailored Blank 용접 판재의 피로거동

오택열,권윤기,이종재,곽대순 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.4

For the Tailor Welded Blank sheet used for automobile body panel, the characteristics of fatigue strength and crack propagation behavior were studied. The thickness of specimen was joined to be same (0.9mm+0.9mm) and different (0.9mm+2.0mm). As a base test, mechanical properties around weld zone were examined. The results indicated that there were no significant decreases in mechanical properties, but hardness around weld bead was 2.3 times greater than base material. The fatigue strength was the highest when the loading direction was parallel to the welding direction, which was about 85% of tensile strength of base metal. It was decreased by 8.5% when the thickness of specimen and base metal was different, and it was increased by 25% when pre-strain was applied. The crack propagation rate was noticeably decreased around weld line and rapidly increased as it passed through weld line. Reviewing the shape of the crack propagation, crack width around weld line was wide around the weld zone due to retardation of crack growth, but it became narrow passing weld line due to decreased toughness.

슬링(sling)과 고정된 지지면에서의 팔굽혀펴기 동작 시 근 활성도 비교

오재섭,박준상,김선엽,권오윤 한국전문물리치료학회 2003 한국전문물리치료학회지 Vol.10 No.3

Bacillus cereus에 있어서 Phospholipase C활량에 관한 몇가지 계면활성제의 영향

권오용,윤희주,한수자 충남대학교 자연과학연구소 1987 忠南科學硏究誌 Vol.14 No.2

This study demonstrates the effects of four detergents and three on the activity change of phospholipase C which is prepared from the cultural broth of Bacillus cereus. This assay of phospholipase C activity was carried out with phosphatidylcholine micelles which were mixed with the detergents and sterols, with increase a molar ratio of these compounds to phosphatidylcholine. Phospholipase C was highly activated at 0.5 molar ratio of Tween 80-mixed micelles. In the case of Triton X-100, it was activated at higher molar ratio indicated 1.0. Sodium dodecyl sulfate was more effective than that of the other detergents at lower molar ratio. However sodium deoxycholate-mixed micelles increased the activity more 7 times than that of the control group. This maximum activation was occurred at 2.5 molar ratio and the turbidity was gradually decreased. Cholesterol and ergosterol increased the activity until molar ratio reached up to 0.9. But the activity was higher at 0.3 molar ratio for stigmasterol. Consequently, it was indicated that phospholipase C was activated with the supplement of detergents until the mixed micelles made a number of small and spherical shape.

連翹敗毒散加味方이 알러지성 접촉피비염에 미치는 影響 : DNCB 재노출부위의 생쥐 피부손상완화와 비만세포 분포 변화를 중심으로 Based on the mitigation of skin damage and distributive change of mast cell on DNCB re-expasure region of Mice

권오성,김진택,박인식,안상현,이해풍,김호현,강윤호 동국대학교 한의학연구소 1999 東國韓醫學硏究所論文集 Vol.8 No.1

본 실험은 連翹敗毒散加味方이 알러지성 접촉피부염 유발시 발생되는 면역과민반응과 염증반응 저해에 미치는 영향을 조사하기위해 행해진 것으로 2,4-dinitrochlorobenzene(DNCB, 5% DNCB 25㎕로 감작, 7일경과 후 2.5% DNCB 5㎕로 유발) 처리로 알러지성 접촉피부염이 유발된 ICR계 암컷 생쥐에 連翹敗毒散加味方抽出物(0.51g/㎏/day)을 음용투여 한 다음 contact hypersensitivity assay, 피부의 일반적인 구조 그리고 비만세포의 분포 변화를 관찰하였다. Contact hypersensitivity assay의 결과, 連翹敗毒散加味方抽出物 투여군의 ear swelling이 DNCB군에 비해 유의성있게 감소한 것으로 나타났다. 알러지성 접촉피부염 유발 후 관찰되는 피부손상은 48시간에 제일 심한 것으로 관찰되었으나, 連翹敗毒散加味方抽出物 투여군에서는 DNCB군 비해 완화된 결과를 보였다. 連翹敗毒散加味方抽出物 투여군의 진피에서 림프구를 비롯한 염증관여세포의 이주와 혈관생성 그리고 표피내로의 림프구의 침윤 등이 감소되었고, 표피 기저층과 가시층세포에서는 세포질내 액포화와 세포사이 공간 확장도 줄어든 것으로 관찰되었다. 한편 알러지성 접촉피부염 유발 후 분포가 증가한 비만세포는 형태가 주로 세포내 함유물이 분비된 degranulated type로 나타났다. 이에 반해 連翹敗毒散加味方抽出物 투여군는 DNCB군에 비해 출현 비만세포'수가 일부 감소했고, 비만세포의 형태는 granulated t-ype였다. 또한 serotonin 면역조직화학적 염색결과로 連翹敗毒散加味方抽出物 투여군에서 se-rotonin 양성반응성이 높은 granulated type의 비만 세포가 주로 관찰되었다. 이상의 결과로 미루어 連翹敗毒散加味方抽出物은 알러지성 접촉피부염으로 유발된 피부 손상과 염증을 완화시키는 효과가 있는 것으로 사료된다. After allergic contact dermatitis elicitated by Dinitrochlorobenzene(DNCB) treatment, ICR female mice administered Yunkyopaedocksangamibang(YPGM) extract were observed to investigate the effect of YPGM on allergic contact dermatitis. This study investigated that contact hypersensitivity assay, abdominal skin morphologic changes including mast cells. At contact hypersensitivity assay, the right ear swelling in YPGM group were probability decrease than DNCB group. At obsevation of abdominal skin morphologic change, the infilteration of lymhocyte, lymphocyte insertion to epithelium, enlarged capillary, angiogenesis, and damages of epithelium as cytoplasmic vacuolation and enlarge of inter cellular space in YPGM were diminshed than DNCB group. The number of mast cell was increased both DNCB and YPGM group. The shape of mast cell in DNCB group was mainly appeared degranulated type, but granulated type in YPGM group. The number of serotonin positive cell was increased both DNCB and YPGM group. The shape of serotonin positive cell in DNCB group was mainly appeared degranuled type, but granulated type in YPGM group. As results indicated that the YPGM exrtact administration work on the mitigation of skin damages in mouse with allergic contact dermatitis.

600합금의 미세조직 변화 및 SCC거동에 미치는 Ce 첨가의 영향

권오철,이용선,임연수,정만교,김정수 대한금속재료학회 2005 대한금속·재료학회지 Vol.43 No.1

High purity model alloys with major composition Ni-15Cr-9Fe-0.03C (600CEO) and Ni-15Cr-9Fe-0.03C-0.04Ce (600CE4) were produced. Using these model alloys the effect of alloying element Ce on the SCC behavior of Alloy 600 was evaluated in a caustic solution. To obtain carbides precipitated on grain boundaries, the thermal treatment was performed on both the solution annealed model alloys. Microstructural examinations using SEM and TEM EDX showed that the same structural carbides, Cr_(7)Cc₃, were precipitated on both the alloys and no significant difference in the amount of Cr depletion along grain boundaries was observed between the two model alloys. However, it was shown that the coverage of grain boundary carbides was higher in the Ce-bearing alloy (600CE4). The SCC susceptibility of the alloys was investigated in 40%NaOH solution at 315℃. Being evaluated in terms of the maximum crack depth, the SCC susceptibility of the alloy turned out to be reduced by the addition of Ce. The increased resistance to the SCC in the alloy 600CE4 was considered to be attributable to the increased coverage of grain boundary carbides. (Received September 30, 2004)

남자 노인에서 족관절 족저 굴곡근 신장운동이Functional Reach에 미치는 효과

권오윤,한명석,박동식 大韓再活醫學會 1999 Annals of Rehabilitation Medicine Vol.23 No.3

Chloroform 용매 중에서 Aniline과 Iodine간의 Charge Transfer Complex 형성 Mechanism에 대한 연구

권오윤,崔相元,金南政 여수대학교 1989 論文集 Vol.3 No.-

The formation of charge transfer complex between indine and aniline in chloroform solvent have been studied kinetically by using conductivity method. The initially formed outer charge transfer complex was transformed into a inner charge transfer complex. The pseudo first order rate constants and aitivation entropy are affected by aniline concentration. The second order rate constants for the decomposition of the outer charge transfer complex(first order in aniline and in the outer charge transfer complex) depend on the aniline concentration. The ease with which the transformation proceeds depends on the relative magnitudes of the enthalpy of formation of the outer charge transfer complex as well as dielectric properties of aniline.

전하이동 착물형성에 따른 Mechanism 및 용매의 영향

權五윤,崔相元,徐鎬埈 여수대학교 1989 論文集 Vol.3 No.-

The formation of charge transfer complex between iodine and aniline in CHCl₃CHCl₄: CH₂Cl₂(1:1), CH₂Cl₂have been studied kinetically by using conductivity method. The initially formed outer charge transfer complex was transformed into a inner charge transfer complex. The pseudo first order rate constants and activation entropy are affected by solvent dielectric constant. The second order rate constants for the decomposition of the outer charge tranfer complex (first order in aniline and in the outer charge transfer complex) depend on the aniline concentration. The ease with which the transfermation proceeds depends on the relative magnitudes of the enthalpy of formation of the outer charge transfer complex as well as aniline concentration.

n-Hexane에서 Aniline, N,N-dimethylaniline, Pyridine과 Iodine간의 Complex 형성에 따른 열역학적 성질에 대한 연구

권오윤,김응렬 漢陽大學校 基礎科學硏究所 1988 基礎科學論文集 Vol.7 No.-

n-Hexane 중에서 aniline, N,N-dimethylaniline, pyridine과 iodine간의 charge transfer complex 형성에 따른 열역학적 성질을 constant activity method를 이용해서 조사하였다. 용액중 iodine, activity를 일정하게 유지하기 위하여 tetramethyl ammonium pentaiodide를 사용하였으며, 이들 complex에 대한 isosbestic point를 분광학적인 방법으로 측정한 결과 aniline, N,N-dimethylaniline 및 pyridine에 대하여 각각 495, 513.5, 478nm 이었다. 25℃에서 aniline, N,N-dimethylaniline 및 pyriod과 iodine각의 complex 형성에 대한 평형상수는 각각 3.1, 30.86, 118.91·??이었으며, 속도 상수는 ??,??,??로 나타났다. 그리고 열역학적 parameter, ΔG는 -0.672, -2.030, ?? 이며, ΔS는 각각 -24.7, -34.3, ??, ΔH는 8.02, 12.26, ??이었다. The thermodynamic properties of iodine complexes with aniline, N,N-dimethy laniline, pyridine in n-hexane were studied by constant activity method. To maintain constant iodine activity in solution, we made use of ??(tetramethylammonium-pentaiodide) Isosbestic points measured by spectroscopic method were aniline:495nm, N,N-dimethylaniline:513.5nm, pyridine:478nm, respectively. Spectroscopic measurement was done at these iosbestic spoint, and experimental results for each iodine complexes with aniline, N,N-dimethylaniline, pyridine are following; equilibrium constant:3.11, 30.86, ??, rate constant :??, ??, ??, and thermodynamic parameters, ΔG:-0.672, -2.030, ??, ΔS:-24.7, 34.3, ??, and ΔH:8.02, 12.26, ??.