피로수명예측을 위한 잔류강도 저하모델의 파라미터 결정법 제안(II)

김상태,장성수,Kim, Sang-Tae,Jang, Seong-Su 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.9

A new method of parameter determination in the fatigue residual strength degradation model is proposed. The new method and minimization technique is compared experimentally to account for the effect of tension-compression fatigue loading of spheroidal graphite cast iron and graphite/epoxy laminate. It is shown that the correlation between the experimental results and the theoretical prediction on the fatigue life and residual strength distribution using the proposed method is very reasonable. Therefore, the proposed method is more adjustable in the determination of the parameter than minimization technique for the prediction of the fatigue characteristics.

의학상식-스트레스와 정신건강

김상태,Kim, Sang-Tae 한국건강관리협회 1985 건강소식 Vol.9 No.12

의학상식-아픔'만성통증'의 정체

김상태,Kim, Sang-Tae 한국건강관리협회 1985 건강소식 Vol.9 No.11

흰쥐 정소세포에서의 Cadmium 독성 작용과 Selenium 전처리의 영향

김상태,부문종,최임순 ( Sang Tae Kim,Moon Jong Boo,Rim Soon Choe ) 한국환경생물학회 1990 환경생물 : 환경생물학회지 Vol.8 No.1

To investigate the cadmium toxicity to testis and the effect of selenium pretreatment, male rats were subcutaneously injected with Cd and/or Se prior to Cd. In doing so, the respiration rates of mitochondria, the lysosomal activities of acid phosphatase and the cellular levels of GSH were measured. Also, the testicular ultrastructures were observed. Cd only-treated group showed that the respiration rates of mitochondria, the lysosomal activities of acid phosphatase and the level of GSH were reduced on the whole. In contrast to above group, Se-pretreated group appeared to be recovered: the respiration rate was restored more than that of control group and the enzyme activity was restored somewhat, however less than that of the control group. The level of GSH was recovered to the level of control group in Se-pretreated group. According to ultrastructural studies, Cd-treated group showed the swelling and destruction of mitochondria and the production of lipid droplets. In contrast, Se-pretreated group appeared not to be different from control group. So, all of these results would indicate that Se has a protective function against Cd toxicity in the rat testis.

직장인의 건강관리-직장인의 스트레스와 정신장애

김상태,Kim, Sang-Tae 한국건강관리협회 1987 건강소식 Vol.11 No.1

직장인의 스트레스와 나아가 이로 인한 정신장애의 극복책은 우선적으로 스트레스의 바른 해소책 개발과 인격적 취약성의 자각 및 인격 성숙을 위한 부단한 노력 이다.

지식정보화 사회를 대비한 특수재능보유자 전형

김상태,Kim, Sang-Tae 한국대학교육협의회 2000 大學敎育 Vol.105 No.-

2000 산업기반기술개발사업 안내

김상태,Kim Sang-Tae 한국공학기술학회 2000 공학교육과 기술 Vol.7 No.2

Arbutin , Glycolic Acid , Kojic Acid 및 Pentadecenoic Acid가 in vitro 및 in vivo에서 UVB 조사에 의한 색소형성에 미치는 영향

김상태,서기석,채영수,엄상철 ( Sang Tae Kim,Kee Suck Suh,Young Soo Chae,Sang Cheul Eom ) 대한피부과학회 1994 대한피부과학회지 Vol.32 No.6

멜라닌 색소의 합성을 조절하는 정확한 기전은 확실치 않지만 유전적 요인 이외에 자외선이나 호르몬과 같은 여러 물리적, 화학적, 생리적 요인이 멜라닌 합성을 조절한다고 알려져 있다. 자외선 조사 후 멜라닌 색소의 증가는 주로 색소세포내 tyrosinase의 활성화와 활동성 멜라닌 세포 수의 증가에 기인한다. 한편 멜라닌 세포의 증식을 감소시키고 멜라닌 합성을 억제하는 화합물로는 hydroquinone, monobenzylether of hydroquinone과 같은 catechol과 phenol화합물이 알려져 있으며 vitamin A 유도체인 trans-retinoic acid와 포화 dicarboxylic acid인 azelaic acid 등도 멜라닌 세포의 증식과 멜라닌 합성을 억제한다고 보고된 바 있다. 최근 arbution(hydroquinone-β-D-glucopyranoside), glycolic acid(GA), kojic acid(KA) 및 pentadecenoic acid(PDA) 등의 색소형성 억제 작용이 제시되고 있다. 이 중 hydroquinone 유도체인 arbutin은 세포 독성이 약하나 색소 형성을 상당히 억제하여 악성 흑생종 세포에서 멜라닌 색소 형성을 저하시킨다는 것이 알려졌으며, 탈피술(chemical peeling)에 사용되고 있는 GA는 eumelanin 합성을 억제하는 vitamin C와 화학적 구조가 유사하므로 GA가 멜라닌 세포와 피부 색조에 영향을 미칠수 있을 것으로 생각되나 확실히 규명된 바 없다. KA[5-hydroxy-2(hydroxymethyl)-4-pyrone]는 구리 이온과 결합하여 tyrosinase의 활성도를 억제하고 dihydroxy indol caboxylic acid로의 전환을 억제함으로서 색소 형성을 저하시킨다고 하며, PDA는 다중부포화 지방산으로 premelanosome의 구조를 변화시키고 멜라닌 색소 중합체의 형성과 peroxidase 활성도를 억제하는 등의 기전으로 색소 형성을 저하시킨다고 추정되고 있다. Arbutine, KA 및 PDA가 흑색종 세포 배양에서 멜라닌 색소 형성을 저하시킨다는 것이 알려졌으나 이들 약물이 배양된 정상 인체 멜라닌 세포에 미치는 영향과 in vivo에서의 멜라닌 세포 수와 형태학적 변화에 미치는 영향은 아직 확실치 않다. 이에 저자들은 배양된 정상 인체 멜라닌 세포와 B-16 흑색종 세포 및 C57EL 흑색 생쥐 피부에 이들 약물을 투여하거나 도포하여 배양된 멜라닌 세포와 B-16 흑색종 세포에서는 세포 수와 멜라닌 양을 측정하고 C57BL 흑색 생쥐에서는 DOPA 염색을 시행하여 멜라닌 세포의 수적, 형태학적 변화를 관찰함으로서 UVB를 조사하지 않은 상태에서의 색소형성 억제 효과를 알아 보고자 하였다. 그리고 배양된 멜라닌 세포와 B-16 흑색종 세포 C57BL 흑색 생쥐 피부 및 인체 피부에 각각 UVB를 조사한 후 이들 약물을 투여하여 UVB 조사에 의한 색소형성에 미치는 영향을 알아보기 위해 본 연구를 시행하였다. Background:Melanin pigmentation palys a major role in normal skin color. The rates of melanin synthesis by melanocytes appear to be regulated by ultraviolet-B UVB) rediation and chemicals, though the precise mechanisms modulating human epidermal pigmentation are unknown. Several chemicals including arbutin, kojic acid(KA), pentadecen?ic acid(PDA) and glycolic acid(GA) have been suggested as a melanogenesis inhibitory compounds because of their chemical or biological similarities with hydroquinone or their tyrosinase inhibitory effcet. Objective:The purpose of this study was to evaluate the inhibitory effect of arbutin, GA, KA and PDA on UV-induced melanogenesis in the in vitro and in vivo pigmentary system. Methods:Cultured normal melanocytes and B-16 melanoma cells, and C57BL mice and human volunteers were used for in vitro and in vivo studies respectively. They were administered to UVB irradiated or nonirradiated cultured normal human melanocytes, and B-16 melanoma cells. For the in vivo study, these chemicals were topically applied to C57BL mice and human ?olunteer skin after UVB irradiation. Numeric and morphologic changes and melanin content were measured in cultured normal human melanocytes and B-16 melanoma cells. In the C57BL mice, numeric and morphologic changes of split-DOPA stained melanocytes were assessed. In the human volunt?rs, gross pigementary changes wre evaluated. Results 1. The number and melanin content of cultured melanocytes initially decreased after UVB-irradiation, but the melanin content increased 5 days after irradiation. 2. Cell numbers of irradiated or nonirradiated cultured human melanocytes decreased in arbutin(10^-3M), KA(10^-3M, 10^-5M), PDA(10^-3M) groups. Those of the cultured B-16 mealnoma cells decreased only in the arbutin(10^-3M) group after UVB irradiation. 3. Melanin contents of cultured human melanocytes decreased in crbutin(10^-3M, 10^-5M), KA(10^-3M, 10^-5M) and PDA(10^-3M) groups. Those of cultured B-16 melanon a cells decreased in arbutin(10^-3M, 10^-5M) groups after UVB-irradiation or nonirradiation. 4. The number of split-DOPA(+) melanocytes decreased in the groups ?reated with KA 1% for 3,5 and 7 weeks, KA 0.1%, arbutin 3%, arbutin 5% for 5and 7 qwwks and PDA 5.0% for 7 weeks in the C57BL mice. 5. The number of split-DOPA(+) melanocytes decreased in the groups ?reated with KA 1.0%, PDA 5.0%, arbutin 3% and arbutin 5% for 5 and 7 weeks and KA 0.1% for 7 weeks in UVB irradiated C57BL mice. 6. Visible inhibition of UVB-induced hyperpigmentation was observed in arbutin applied sites in 4 of the 6 volunteers 3 weeks after the application. GA did not show an inhibitory effect on UVB-induced hyperpigmentation in all subjects. Conclusion:Arbutin, KA, PDA had a suppressive effect on ? of nonirradiated melanocytes and melanoma cells as well as UVB-induced hyperpigmentation. It is suggested that these drugs might be candidates as compounds that may control hyperpigmentary disorders.(Kor J Dermatol 1994;32(6):977~989)

정신병과 건강생활-정신건강이란 무엇인가

김상태,Kim, Sang-Tae 한국건강관리협회 1976 건강소식 Vol.4 No.9

주입선 형태가 타이타늄 합금의 주조성에 미치는 영향

김상태,방몽숙,양홍서,박상원,박하옥,임현필,Kim, Sang-Tae,Vang, Mong-Sook,Yang, Hong-So,Park, Sang-Won,Park, Ha-Ok,Lim, Hyun-Pil 대한치과보철학회 2007 대한치과보철학회지 Vol.45 No.4

Statement of problem: Despite of the recent development of the titanium casting system methods, the casting defects such as imperfect casting and internal porosity were frequently observed. Purpose: The purposes of this study were to compare and measure the castability, microhardness, and surface reaction between Grade 2 pure titanium and Ti-6Al-4V by casting these alloys from the different sprue design conditions. Material and methods: Depending on the sprue designs and titanium alloys, 42 ready-made wax patterns were used. By analyzing the remodeling of the cast, internal porosity, microhardness, and titanium surface layer of SEM, there were several results we observed. Results: 1. The measured castability of titanium were categorized in the ascending order: individual sprue group, runner bar group, and single group. This data are based on the statistically signigicant differences. 2. The castability of titanium has not showed the statistically significant differences among the alloys. However, CP-Ti groups were superior to Ti-6Al-4V groups by showing the noticeable castability. 3. The surface layers of the castings of all groups have showed $5{\mu}m$ titanium oxide layers irrespective of sprue designs and titanium alloys. Conclusion: From the above study results, by fabricating the restorations from the centrifugal casting machine direct sprue designs revealed better castability. As we increased the number of sprues in the wax pattern, it revealed better castability. The castability of pure titanium rather than that of Ti-6Al-4V was remarkable. To fabricate the complex forms of the restorations, further researches on the efficient sprue designs and titanium alloys must be made.