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임문혁,김문석,김희중 啓明大學校 産業技術硏究所 1997 産業技術硏究所 論文報告集 Vol.20 No.-
It was well known that 70-80% of the fracture of steel plate was due to fatigue fracture. A fatigue behvaior of infinite steel plate was examined in this study. The stress concentration phenomenon around the hole in the steel plate was an important factor for the fatigue fracture. The diameter of the holes existing in the steel plate were varied from 0.1mm up to 0.4mm, and the number of hole was 1 and 3 in this study. It was shown that the stress concentration was exponentially increased as the angle of the crack in the plate was decreased. The initial value of stress concentration was smoothly increased as the diameter of hole was when the hole existed in the steel plate logarithmically decreased as the angle of hole was decreased. As a result of this study, it was found that the fatigue strength decreased extreamly when the small hole occurred in the steel plate. Consequently, greate care for fatigue strength should be excercised in designing steel mumbers.
Kim, Do Rim,Kim, Hyu Young,Kim, Ha Young,Chang, Mun Seog,Park, Seong Kyu Hindawi Publishing Corporation 2015 Evidence-based Complementary and Alternative Medic Vol.2015 No.-
<P>Genetic defects during spermatogenesis can lead to a reduction in sperm motility and cause male infertility. The cation channels of sperm (CatSper) play a role in the regulation of hyperactivated sperm motility in mouse testes. The effect of <I>Trigonellae</I> Semen (TS) on the male reproductive system and CatSper protein in mouse testes during spermatogenesis was examined. C57BL/c mice were divided into the following five groups: normal, cyclophosphamide- (CP-) only treated (control group), and three groups treated with varying concentrations of TS with CP (100, 500, and 1000 mg/kg TS and 100 mg/kg CP). Real-time PCR, western blot analysis, and a testosterone immunoassay were performed to assess CatSper protein levels in the five groups. Additionally, sperm cell counts and motility were examined. Results indicate that sperm motility and sperm counts increased in the TS treated groups in a dose-dependent manner (<I>p</I> < 0.01). CatSper levels were also significantly higher in the TS treated groups compared to that of the control group (<I>p</I> < 0.001). Therefore, TS treatment could enhance sperm function by promoting spermatogenesis and the expression of CatSper proteins in mouse testes.</P>
KIM, DAEHWAN,KIM, SO YOUNG,MUN, SEOG KYUN,RHEE, SANGMYUNG,KIM, BEOM JOON UNKNOWN 2015 INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE Vol.35 No.4
<P>Epidermal growth factor (EGF) plays a critical role in fibroblasts by stimulating the production of collagen and supports cell renewal through the interaction between keratinocytes and fibroblasts. It is well known that the contractile activity of fibroblasts is required for the remodeling of the extracellular matrix (ECM), which contributes to skin elasticity. However, the role of EGF in the contraction of aged fibroblasts under 3-dimensional (3D) culture conditions is not yet fully understood. In the present study, we demonstrated that young fibroblasts spread and proliferated more rapidly than aged fibroblasts under 2-dimensional (2D) culture conditions. Cell migration assay using a nested collagen matrix revealed that the migration of young fibroblasts was also greater than that of aged fibroblasts under 3D culture conditions. However, the addition of recombinant human EGF (rhEGF) resulted in the enhanced migration of aged fibroblasts; the migration rate was similar to that of the young fibroblasts. The aged fibroblasts showed decreased cluster formation compared with the young fibroblasts on the collagen matrix, which was improved by the addition of rhEGF. Furthermore, cell contraction assay revealed that the basal contractility of the aged fibroblasts was lower than that of the young fibroblasts; however, following treatment with rhEGF, the contractility was restored to levels similar or even higher to those of the young fibroblasts. Taken together, our results suggest that rhEGF is a potential renewal agent that acts to improve the migration and contraction of aged fibroblasts more efficiently than young fibroblasts under 3D culture conditions; thus, EGF may have valuable regenerative effects on aged skin.</P>
Irreversible Magnetization of MgB₂ Superconductor
Mun-Seog Kim,Kyu-Tae Kim,Wan-Seop Kim,Po Gyu Park,Kyu Won Lee,Sung-Ik Lee 한국자기학회 2005 Journal of Magnetics Vol.10 No.4
We report the magnetic-field dependence of the irreversible magnetization of binary superconductor MgB₂. For the temperature region of T < 0.9Tc, the contribution of the bulk pinning to the magnetization overwhelms that of the surface pinning. This was evident from the fact that the magnetization curves, M(H), were well described by the critical-state model without considering the reversible magnetization and the surface pinning effect. It was also found that the M(H) curves at various temperatures scaled when the field and the magnetization were normalized by the characteristic scaling factors H*(T) and M*(T), respectively. This feature suggests that the pinning mechanism determining the hysteresis in M(H) is unique below T = Tc.
Transplantation of autologous perichondrium with amniotic membrane for progressive scleral necrosis
Kim, Jee Taek,Kim, Kyoung Woo,Mun, Seog-Kyun,Chun, Yeoun Sook,Kim, Jae Chan Elsevier 2019 The ocular surface Vol.17 No.3
<P><B>Abstract</B></P> <P><B>Purpose</B></P> <P>Scleral necrosis with severe ischemia is refractory to conventional treatment because of avascular progressive necrosis. We assessed the therapeutic efficacy and safety of autologous perichondrium transplantation in patients with progressive scleral necrosis (PSN) and analyzed the clinical effects.</P> <P><B>Methods</B></P> <P>This study was a prospective, interventional, and noncomparative case series. Reconstructive surgery using autologous perichondrium and amniotic membrane (AM) was performed in patients with PSN who showed progressive ischemic scleral melting with impending perforation state and/or broad avascular area larger than 10 mm in diameter. The primary outcome was restoration of scleral integrity with healthy vascularized epithelium over the graft at six months after surgery. The secondary outcome was complication rate associated with autologous perichondrium graft use.</P> <P><B>Results</B></P> <P>Eighteen eyes of 14 patients underwent reconstructive surgery using autologous perichondrium patch and AM grafts. Observations indicated the graft provided the eyeball with successful structural integrity in 17 out of the 18 cases (94.4%) at six months after surgery. One eye showed a small scleral defect due to wound dehiscence at four month after the surgery. Additional surgery using perichondrium and AM stabilized the eye. The scleral necrosis healed completely after perichondrium and AM transplantation, even in cases with full-thickness scleral defect. The scleral integrity was maintained until the last follow-up session. There were no serious complications of endophthalmitis or graft infection.</P> <P><B>Conclusions</B></P> <P>Reconstructive surgery using autologous perichondrium and AM is an effective method for restoration of scleral integrity and vascularization of the episclera and conjunctiva in eyes with PSN. Therefore, autologous perichondrium can be considered as an appropriate new biologic tissue for PSN.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Progressive scleral necrosis is refractory to conventional therapy because of its broad ischemic nature. </LI> <LI> Revascularization and epithelialization over the scleral defect are essential for healing the scleral ischemia and ulceration. </LI> <LI> Perichondrium autograft is new effective therapy for progressive scleral necrosis, even for full-thickness scleral necrosis. </LI> </UL> </P>
Kim, Kyu-Tae,Kim, Mun-Seog,Kim, Myungsoo,Niemeyer, J. IEEE 2005 IEEE transactions on instrumentation and measureme Vol.54 No.2
A stable reference source with a high current capability is useful for many metrological applications. Unlike the conventional Josephson voltage standard, one can couple the programmable Josephson voltage standard (PJVS) to a current source below milliamp range to stabilize the current. For higher current ranges, we tested a feedback method which allowed us to stabilize the 0.1-A output current of a commercial current source to within a standard deviation of 2 × 10<SUP>-8</SUP> A/A.