크리프-피로 영향을 고려한 터보펌프 터빈의 손상해석

이무형 ( Mu Hyoung Lee ),장병욱 ( Byung Wook Jang ),김진한 ( Jin Han Kim ),정은환 ( Eun Hwan Jeong ),전성민 ( Seong Min Jeon ),이수용 ( Soo Yong Lee ),박정선 ( Jung Sun Park ) 한국항공운항학회 2010 한국항공운항학회지 Vol.18 No.1

Structures under high temperature may have creep behavior and fatigue behavior. Durability study of the structures need the damage analysis with the creep-fatigue effects. In this paper, the damage analysis is studied for a turbine blade in the turbopump for a liquid rocket engine which is operated under high temperature condition. First of all, the load cycle is required for defining the operational characteristics of turbopump. The thermal stress analysis is done for a turbine blade of the turbopump. The stress analysis results are used to judge damage due to the creep and the fatigue. The strain-life method with miner rule is used for fatigue damage analysis. The Larson-Miller parameter master curve and robinson rule are used for the creep damage analysis. The linear damage summation method is used to consider creep-fatigue effects of turbopump turbine. Finally, the analysis results for fatigue and the influence are compared to figure out the damage phenomenon of the turbopump turbine.

자외선 A와 B에 의한 SK 23 인체 악성 흑색종 세포주의 증식과 멜라닌화

이무형(Mu Hyoung Lee),김진환(Jin Hwan Kim),허충림(Choog Rim Haw) 대한피부과학회 1993 대한피부과학회지 Vol.31 No.5

Background : The visible cutaneous pigmentary response to ultraviolet A(UVA) is immediate, whereas ultraviolet B(UVB)-induced pigmentation appears after a delay of several days. However, some investigators reported that UVA also can induce delayed taniing. Objective : In order to determine whether the pigmentation induceil by UVA irradiation is accompanied by melanocytes responses which are the same or different from those following a UVB-indueed tan, we irraiated malignant melanoma cells to UVA or UVB. Method : On the 7th day after irradiation of UVA or UVB, we exa nined the cell counts and the melanin content of control and experimental groups. Results : Although a dose of 10 J/cm decreased the number of manignant melanoma cells, there was no significant difference between the control and UVA-exposure griiups. But there was a significant decrease after UVB-exposun. UVB-exposure groups showed a significant increase of melanin cortent. A dose of 10 J/cm of UVA also induced a significant increase of melanin content. Conclusions : The data suggest that UVA at a clinically relevant dose has a significant effect on human melanocytes. So, UVA very likely plays a role in the increased, melanization associated with delayed tanning. (Kor J Derrnatol 1993;31(5):732-737)

배양 정상 인체 멜라닌세포의 성장과 멜라니화에 L - 티로신의 영향

이무형 ( Mu Hyoung Lee ),김진환 ( Jin Hwan Kim ),박재경 ( Jai Kyung Park ),허충림 ( Choong Rim Haw ) 대한피부과학회 1996 대한피부과학회지 Vol.34 No.1

Background: The biosynthesis of melanin is initiated by the enzymatic oxidation of L-tyrosine to L-dopa by tyrosinase. Some precursors of melanin are cytotoxic, and melanoma cells are killed as a risk of exposare to excess tyrosine or dopa in the culture medium. However, there have been few observations of the effects of L-tyrosine on cultured normal human melanocyte. Objective : In order to investigate whether exogenous tyrosine induces cytotoxicity in cultured normal human melanocytes as in melanoma cells, we examined the effects of L-tyrosine on proliferation and melanization in normal human melanocytes. Methods : A melanocyte culture was produced with a modified TIC medium. L-tyrosine was added to the culture medium, 100, 200, 400, and 800uM. After 2 days of incubation, the proliferation was measured by methylthiazol tetrazolium(MTT) assay and sulforhodamine B(SRB) assay. The melanin contenis were also measured by the modified Whittaker's method. Results : On MTT assay, the proliferation of melanocytes had been stirnulated significantly (p< 0.05) in all L-tyrosine added groups. On SRB assay, the proliferation of melanocytes had heen stimulated significantly (p<0.05) in 200, 400, 800uM of L-tyrosine added groups. The melanin contents had increased in all L-tyrosine added groups, and had increased significantly (p<0.05) in 400uM of L-tyrosine added group. Conclusion : L-tyrosine is not toxic to normal melanocytes, It stimulates the proliferation and melnization of cultured normal human melanocytes. (Kor J Dermatol 1996;34(1): 25-30)

저한성 외배엽 이형성증

김진환 ( Jin Hwan Kim ),이무형 ( Mu Hyoung Lee ),허충림 ( Choong Rim Haw ) 대한피부과학회 1995 대한피부과학회지 Vol.33 No.5

Hypohidrotic ectodermali dysplasia is a rare and heterogenous genodermatosis that is characterzed by hypohidrosis, hyptrichosis, dental hypoplasia, and a characteristic facies. A 16-month-old male was evaluated for anodontia and anhidrosis since birth. There was no family history of this disease. His face was characterized by a broad nose and sparse eyebrows and periorbital wrirkling. The skin was dry, and scalp hairs were thin and sparse. Skull X-ray finding revealed noth ing remarkable except de;ayed teeth eruption. His developmental status for which we used DDS'I' was slightly reduced on inental development and showed normal on physical development. A skin biopsy was done on skin from the left palm, which showed a few immature eccrine glands in the dermis. We report a typical form of hypohidrotic ectodermal dysplasia with a review of the literature. (Kor J Dermatol 1995;33(5): 961-966)

건선 치료에 대한 Calcipotriol ( MC 903 ) 연고의 임상연구

윤태진(Tae Jin Yoon),김진환(Jin Hwan Kim),심우영(Woo Young Sim),이무형(My Hyoung Lee),김낙인(Nack In Kim),허충림(Choong Rim Haw) 대한피부과학회 1993 대한피부과학회지 Vol.31 No.2

Background: We have already shown that a new vitamin D3 analogue, calcipotriol is a potent growth inhibitor for human keratinocytes, indicating the close relationship between the in vitro inhibitory effect of calciipotriol and its therapeutic effectiveness or psoriasis. Objective : Our purpose was to evaluste the clinical efficscy, safety and tolerability of calcipotriol (50ug/g) ointment twice daily in the treatment of psoriasis. Methods : We treated 31 patients with calcipotriol for 6 weeks. Patients were provided with a maximum of 100g of ointment per week. Efficacy, as measured by the Psoriasis Area and Severity Index(PASI), and safety were assessed at 2,4, and 6 weeks. Results ; Reduction of PASI was stastistically significant at all time points for treatments (p<0.01). At the completian of 6 weeks of treatment, the mean PASI reduction was 3.61. An analysis of patient overall self-assessment, at 6 weeks showed clearance or marked improvement in 61%. Some patients developed minimal irriltation of lesional or perilesional skin(6.5%). Laboratory tests did not show any significant changes, in particular there was no change in serum calcium levels. Conelusions : Calcipotriol ointment was effective as measured by the PASI and the self-assessment in patients with psoriaeis. This treatrnent was well tolerated. (Kor J Dermatol 1993; 31(2): 217-223)

UVB 반복조사가 배양 인체 멜라닌세포의 형태학적 변화와 증식 및 멜라닌화에 미치는 영향

김진환,박재경,허충림,이무형 ( Jin Hwan Kim,Jai Kyung Park,Choong Rim Haw,Mu Hyoung Lee ) 대한피부과학회 1994 대한피부과학회지 Vol.32 No.6

피부는 외부에 노출되어 있으므로 외부의 여러 물리적 또는 화학적 요소들에 의해 영향을 받아 변화하는데, 그중 일광은 항상 접하게 되는 필수적 요소의 하나이다. 일광이 피부에 미치는 영향에는 비타민 D의 합성 등의 인체에 이로운 작용외에도 급성반응으로 홍반이나 색소침착, 만성반응으로 나타나는 피부노화, 피부암의 유발 등은 인체에 유해하거나 미용적인 문제를 야기하게 한다. 이러한 피부변화는 표피세포 뿐만 아니라 진피세포들의 복합적인 작용으로 일어나게 된다. 그러나 표피나 진피를 구성하는 세포 각각의 독립적인 변화를 알아보기 위해서는 구성세포의 분리배양이 필요하다. 특히 멜라닌세포는 일광노출에 의해 멜라닌 합성이 증가됨으로써 피부의 색소침착에 중요한 역할을 담당할 뿐 아니라, 이 합성된 멜라닌이 각질형성세포로 이동함으로써 일광 등에 의한 피부의 손상을 방지하게 된다. 멜라닌세포의 성장과 멜라닌화에 영향을 미치는 요소에는 세포의 유전성 프로그램, 일광, 호르몬, 그밖의 멜라닌 대사에 영향을 주는 화학물질 등이 있다. 그중 일광노출에 의한 변화는 주로 자외선B(이하 UVB라고 약함)에 의해 일어나는데, 일반적으로 생체내 실험에서는 멜라닌 세포수가 증가되며 멜라닌화를 촉진하는 것으로 알려져 있다. 그러나 배양 멜라닌세포를 이용한 실험관내 실험에서는 보고자에 따라 다른결과를 보이는데, 이는 자외선의 조사방법, 조사량, 멜라닌세포의 배양방법, 종족이나 개체간의 멜라닌 세포의 특성의 차이 등으로 인해 나타난 것으로 생각된다. 특히 조사량과 함께 조사횟수 즉, 일회조사한 경우와 반복조사한 경우의 멜라닌세포수나 멜라닌 양은 다르게 나타난다. 저자는 일상생활에서의 일광노출과 유사한 적은 양의 UVB를 배양 인체 멜라닌세포에 반복 조사하여 멜라닌세포의 성장과 분화의 변화를 알아보았다. 또한 동일량의 UVB를 분할하여 반복조사한 경우와 일회조사한 경우에 어떤 차이가 있는지 알아봄으로써 UVB가 실험관내 실험에서 멜라닌세포의 성장과 분화에 미치는 영향을 규명하고자 본 실험을 시행하였다. Background:In the skin, the major stimulus for cutaneous pigineatation is ultraviolet radiation. The most important physiologic role of melanin is protection against harmful UV radiation to skin. It is known there are some differences in melanization between a single and multiple exposures of UB, in vivo. Little if known about the functions of the melanocyte alone in cutaneous pigmentation after ultraviolet exposure, because of the complexity of interactions in the whole epidermis Objective:To investigate the effects of multiple exposures at various dosages of UVB, and to compare the effect of UVB in multiple divided exposures ? a single exposure at the same total dosage of UVB on proliferation and melanization in cultured human melanocyte. Methods:Melanocytes were cultured by modified TIC medium The melanocter were exposed daily for three consecutive days to UVB at 2, 4, 8, and 16 mJ/㎠ and a single exposure at 24 mJ/㎠. The morphologic changes were examined by phase contrast microscopy. The melanocytes were counted by hemocytometer and melanin content;were assayed by spectro-photometer. Results:1. The effects of multiple UVB exposures: 1)The morphologic changes were as follows:With three time exposures at a dosage of 8 mJ/㎠, the melanocytes enlarged in size, and elongated their dendrites slightly;with three time exposures at a dosage of 16 mJ/㎠, enlargement in sized and elongation of dendrited were more significant. 2) With three time exposures at dosages of 2 and 4 mJ/㎠, the proliferation of melanocytes was stiumlated significantly(p<0.05). However, with three time exposures at dosages of i and 16 mJ/㎠ the proliferation was inhibited(p<0.05). 3) With three time exposures at dosages of 2 and 4 mJ/㎠, the melanin contents were decreased. However, with three time exposures at a dosage of 16 mJ/㎠, the melanin contents were highly increased(p<0.01). 2. The comparison between multiple divided exposures and a single exposure at the same toal dosage of UVB: 1) There were no morphologic differences of dendrities between with three time exposures at a dosage of 8 mJ/㎠ and with a single exposure at a dosage of 24 mJ/㎠. However enlarged melanocytes were more numerous with a single exposure. 2) The proliferation of melanocytes was more inhibited with:single exposure than with multiple divided exposures(p<0.05). 3) The melanin contents were more increased with a single exposure than with multiple divided exposures(p<0.05). Conclusion:With multiple exposures at lower dosages of UVB, the proliferation of melanocytes was stimulated, and melanixation was decreased. However, with multiple exposures at higher dosages of UVB, the proliferation was inhibited, and melanization was increased. At the same total dosage of UVB, the proliferation on was more inhibited, and the melanization was more increased with a single exposure than with multiple divided exposures.(Kor J Dermatol 1994;32(6):1035∼1045)

고정약진의 임상 및 병리조직학적 고찰

류지호 ( Ji Ho Ryou ),김진환 ( Jin Hwan Kim ),이무형 ( Mu Hyoung Lee ) 대한피부과학회 1998 대한피부과학회지 Vol.36 No.1

Background: Fixed drug eruptions(FDE) are a cutaneous reaction characterized by one or more circumscribed lesions that recur at the same site in response to a given medication. Objective: The purpose of this study was to find the clinical and histopathological characteristics of FDE and to compare early FDE with late FDE histopathologically. Method: We clinically investigated 54 cases of FDE that visited the department of dermatology at the Kyunghee medical center from January 1993 to December 1996. Among them, 31 patients had skin biopsies and were evaluated histopathologically on the basis of duration. Results .' The results were summarized as follows: 1. Development of FDE did not show any difference according to sex and was evenly distributed over all the ages. 2. The latent periods of FDE were diverse in appearance from 30 minutes to 10 days, but mostly, the skin lesions erupted within 4S hours. 3. The most common skin lesions were erythematous macules. 4. Distribution of the lesions came out as solitary : 20.4%, multiple : 79.6%. S3.7% of the multiple lesions were localized to a part of body, and 16.3% were distributed over the whole body. 5. The areas in which the eruptions developed were (in descending order): upper extremity(37.0%), hand(31.5%), trunk(24.1%), face(24.1%). 6. In most cases(68.6%), the size and the number of lesions were greater in recurrente, rather than in first attacks. 7. The histopathological findings commonly showed perivascular mononuclear cell(MNC) infiltration (100%), pigmentary incontinence(77.4%), basal hydrophic degeneration(71.0%), eosinophil infiltration in dermis(61.3%), etc. 8. The epidermal histopathological findings such as spongiosis, exocytosis of MNC, basal hydrophic degeneration, keratinocyte necrosis and subepidermal vesicles could be seen more frequently in early lesions than in late ones. Conclusion : In our study, we were able to obtain meaningful results based on data from the combination of clinical and histopathological investigations. This study may give help to understand the characteristics of fixed drug eruptions and to plan future studies. (Korean J Dermatol 1998;36(1): 30-36)