• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.40-40
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• 2011

반도체 소자의 미세화와 더불어 세정공정의 중요성이 차지하는 비중이 점점 커지고, 이에 따라 세정 기술 개발에 대한 요구가 증대되고 있다. 기존 세정 기술은 화학약품 위주의 습식 세정 방식으로 패턴 손상 및 대구경화에 따른 어려움이 있다. 따라서 건식세정 방식이 활발하게 도입되고 있으며 대표적인 것이 에어로졸 세정이다. 에어로졸 세정은 기체상의 작동기체를 이용하여 에어로졸을 형성하고 표면 오염물질과 직접 물리적 충돌을 함으로써 세정한다. 하지만 이 또한 생성되는 에어로졸 내 발생 입자로 인해 패턴 손상이 발생하며 이러한 문제점을 극복하기 위하여 대두되는 것이 가스클러스터 세정이다. 가스 클러스터란 작동기체의 분자가 수십에서 수백 개 뭉쳐 있는 형태를 뜻하며 이렇게 형성된 클러스터는 수 nm 크기를 형성하게 된다. 그리고 짧은 시간의 응축에 의해 수십 nm 크기까지 성장하게 된다. 에어로졸 세정과 다르게 클러스터가 성장할 환경과 시간을 형성하지 않음으로써 작은 클러스터를 형성하게 되며 이로 인해 패턴 손상 없이 오염입자를 제거하게 된다. 이러한 가스 클러스터 세정을 최적화하기 위해서는 설계 단계부터 노즐 내부 유동의 수치해석에 기반한 입자 크기 분포를 계산하여 반영하는 것이 필요하다. 따라서 본 연구에서는 상용 수치해석 프로그램을 이용하여 세정 환경을 조성하는 조건에서의 노즐 내부 유동을 해석하고, 이를 통해 얻어진 수치를 이용하여 aerosol general dynamic equation (GDE)를 계산하여 발생하는 클러스터의 크기 분포를 예측하였다. GDE 계산 시 입자의 크기 분포를 나타내기 위해서는 여러 가지 방법이 존재하나 본 연구에서는 각 입자 크기 노드별 개수 농도를 계산하였다. 노즐 출구에서의 가스 클러스터 크기를 예측하기 위하여 먼저, 노즐 내부 유속 및 온도 분포 변화를 해석하였다. 이를 통하여 온도가 급격하게 낮아져 생성된 클러스터의 효과적 가속 및 에너지 전달이 가능함을 확인할수 있었다. 이에 기반하여 GDE를 이용한 입자 크기를 예측한 결과 수 나노 크기의 초기 클러스터가 형성되어 온도가 낮아짐에 따라 성장하는 것을 확인할 수 있었으며, 최빈값의 분포가 실험적 측정값과 일치하는 경향을 가지는 것을 볼 수 있었다. 이는 향후 확장된 영역에서의 유동 해석과 증발 등 세부 요소를 고려한 계산을 통해 가스 클러스터 세정 공정의 최적화된 설계에 도움이 될 것이다.

• Applied Microscopy
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• v.30 no.1
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• pp.11-20
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• 2000

The morphological changes in normal and weathering hair shafts of the human scalp were investigated by using the transmission and scanning electron microscopes. The hair shaft composed of cuticular layer, cortex and medula. The surface of normal hairs are smooth and covered by imbricated cuticular scales. The cuticular layer consists of five to seven cuticle cells. These cells, which are flat and thin, measuring about $100{\mu}m$ long and $0.4{\mu}m$ thick, appears intercellular membrane complex in diameter 25 nm. The cortex composed of melanin granules and cornified cells, which multicomponent concentric microfibrils in diameter about 8 nm give rise to macrofibrils in diameter $0.5{\mu}m$ to $0.8{\mu}m$ encased in limiting membrane. The melanin granules are spherical shaped about $0.5{\mu}m$ in size and scattered between macrofibrils. The medulla in the normal hairs are $16{\mu}m$ in diameter centrally region of cortex. Normal hair shafts undergo progressive degenerative changes due to a variety of environmental insults. In the initial weathering process of hair, the cuticular scales became irregularly raised and broken, and then cuticle cells formed cytoplasmic vacuolation, following dissociated intercellular membrane complex, ultimately entirely lost and nuded cortex. Occasionally, transverse fissures were seen at hair shafts indicating that the hairs were deteriorated. Complete removal of the cuticular layer in the heavily damaged cortex portions appeared splitting of the cortical cell into its macrofibrils and scattering of melanin granules.

• Korean Journal of Food Science and Technology
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• v.49 no.5
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• pp.507-512
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• 2017

The physicochemical properties of maize starch sonicated at various amplitudes (100, 200, and 300 W) and times (10, 30, and 50 min) were examined. The amount of enzyme-susceptible starch increased marginally after sonication. Sonication increased the amount of oil absorbed in the starch although the degree of oil absorption decreased with an extension of the sonication time, implied that different types and extent of damages occurred. Scanning electron microscopy revealed that ultrasound sonication did not form pores on the surfaces, but caused damages such as depression and erosion. Pasting viscosity of starch decreased with an increase in the severity of sonication conditions because of the weakened polymer network. X-ray diffraction suggested that the crystalline domains in starch were not susceptible to sonication and were more resistance to degradation. Sonicated starch formed more pin-holes on the surfaces in the initial glucoamylase reaction; subsequently, as the reaction proceeded, porous starch with enlarged pores was formed and finally, disrupted granular fragments were observed.

• Journal of Conservation Science
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• v.32 no.2
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• pp.235-247
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• 2016

Conventional imaging techniques such as ultraviolet, infrared, and X-ray are used mainly to diagnose the damaged parts of the painted cultural assets in Korea. These techniques, however, have limits in diagnosing damages of interlayer parts. We have performed and extensive study on the applicability of Terahertz(THz) analysis technique, introduced recently to this field of study on cultural properties in Korea, to diagnose painted cultural assets. The specimens, produced to imitate the damage types of Korean painted properties, were analyzed over their painting, supporting, and backing layers by terahertz pulse imaging technique. The analyzed results provided information about the cracks, the separated areas, and the separated distances between layers on the specimens. Our research, then, was extended to real painted cultural remains, Birojana Sam-shin Gwebul-do at Bongseon Temple in Namyang-ju, Korea National Treasure Number 1792, through which we have obtained 3D information about the extent and pattern of damages to the asset. These results demonstrate that terahertz 3D imaging technique has the capability of noncontact 3D diagnosis on painted cultural properties.

• Journal of Chest Surgery
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• v.29 no.8
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• pp.807-815
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• 1996

The protective effect of'ischemic preconditioning'on ischemid-reperfusion injury of heart has been reported in various animal species. but without known mechAnism in detail, In An attempt to investigate the cardioprotective mechanism of ischemic preconditioning, we examined the effects of nitric oxide(UO) synthesis in preconditioned heart of rat The isolated hearts perfused by Langendorfr's method were ex- posed to 30min global ischemia followed by 30min reperfusion with oxygenated Krebs-Henseleit(K-H) sol- ution. Ischemic preconditioning was performed with three episodes of Sm n ischemia and Smin repeyfusion before the induction of prolong ischemia(30min)-reperfusion(30min). Ischemic preconditioning prevented the depression of cardiac function(left ventricular pressure .K heart rate) observed in the ischemia- reperfusion hearts and reduced the release of lactate dehydrogenase during the reperfusion period. On electromicroscopic pictures, myocardial ultrastructures wore relatively well preserved in isthemic preconditioned hearts. N6_nitro-L-arginine methyl ester(L-NAME) an inhibitor of L-arginine citric oxide pathway, was infused at a rate O.Smllmin In a dose of 10mg kg-1 before the initial ischemic preconditioning. neither the protection of cardiac function nor the reduction of LDH releAse in ischemic preconditioning hearts was altered in the presence of added L-NAME On ultrastructural finding, the preservation of morphology in ischemic preconditioning heart was not change by the pretreatment of L-UAME. The failure of the WO synthesis inhibitor to reduce t e effect of ischemic preconditioning may be related to be species specific in that NO may allot be the trigger for ischemic preconditioning in rats.

• Journal of the Korean Arthroscopy Society
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• v.4 no.1
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• pp.32-37
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• 2000

Purpose : We performed routinely arthroscopy to diagnose and treat intra-articular soft tissue pathology and tibial condylar fractures. The purpose of this study was to evaluate clinical value of arthroscopy in the tibial condylar fractures. Materials and Methods : The 31 tibial condylar fractures was examed by routine arthroscopy, 9 treated by conservative method and 22 treated by surgery at least follow up of 12 months. The authors analysed to the cause, classification, soft tissue injuries such as ligaments and menisci, treatment and results. Results : The most common type was Schatzker classification type I in 15 cases$(18\%)$ and intra-articular lesions and associated ligament injury were in 21 cases$(67\%)$. Most common lesion was meniscal tear in 16 cases and most common type of meniscal lesions was peripheral detachment in 7 cases$(44\%)$. Schatzker I, II fracture patterns were associated with the highest frequency of soft tissue injuries, especially medial collateral ligament and meniscal injuries. Conclusion : Arthroscopic examination is useful method to evaluate the intra-articular pathology and to treat the tibial condylar fractures.

• Journal of Embryo Transfer
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• v.12 no.3
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• pp.325-333
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• 1997

수정란이식의 주변기술인 초기배의 미세조작및 성 판정은 가축의 경우, 경제 형질의 유전적 개량에 크게 기여하였다. 본 연구는 미세조작 biopsy와 PCR에 의한 체외생산 소 초기배의 급속. 정확한 성 판정 기법을 확립하기 위해 실시하였다. 체외성숙 및 체외수정에 의해 생산된 소수정란은 소 난관상피세포와 공배양을 통해 8-세포부터 배반포시시까지 체외발생시킨 후 미세조작 biopsy에 이용되었다. 미세조작 biopsy 과정중에 약간의 형태적인 손상이 관찰되었지만 대부분의 demi-embryo는 정상적인 배반포와 나화배반포로 발생하였다. 8~16 세포, 상실배, 초기배반, 포 시기에서 미세조작 biopsy 후 확장 또는 나환배반포기시기까지의 발달율은 각각 62.8(27/43), 83.3(30/36) 및 80.9%(55/68)로 정상적인 초기배와 큰 차이가 없는 것으로 나타났다. 총 136개의 소 초기배로 부터 2~10개의 할구세포를 미세조작 biopsy에 의해 분리하여 소 특이와 Y-특이염기서열을 가진 두 쌍의 염기서열을 이용하여 PCR을 수해하였다. 이들중 112(82.4%)개를 성공적으로 성 판정하였으며, 암/수 비율은 각각 34.8(39/112)/65.2%(73/112)로 나타났다. 본 실험에서 얻은 결과는 확립된 소 초기배의 미세조작기술과 성 판정 방법을 통해 계획적인 암.수 송아지의 선별 생산뿐만 아니라 소 수정란 이식을 통한 유전적 개량을 촉진시키는데 효과적으로 이용될 수 있는 기술이 확립된 것을 보여주었다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.4
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• pp.672-678
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• 2002

Oxidative stress contributes to cellular injury following clinical and experimental ischemia/reperfusion scenarios. Oxidative injury can induce cellular and nuclear damages that result in apoptotic cell death. We tested the hypothesis that the catechin flavonoid of (-)epigallocatechin gallate, a green tea polyphenol, inhibits hydrogen peroxide ($H_2O$$_2$)-induced apoptosis in human umbilical vein endothelial cells. The effect of apigenin, a flavone found in citrus fruits, on apoptosis parameters was also examined. A 30 min pulse treatment with 0.25 mM $H_2O$$_2$ decreased endothelial cell viability within 24 hrs by > 30% ; this was associated with nuclear condensation and biochemical DNA damage consistent with programmed cell death. In the 0.25 mM $H_2O$$_2$apoptosis model, 50${\mu}{\textrm}{m}$ (-)epigallocatechin gallate markedly increased cell viability with a reduction in the nuclear condensation and DNA fragmentation. In contrast, equimicromolar apigenin increased cell loss with intense DNA laddering, positive nick-end labeling and Hoechst 33258 staining. Thus, polyphenolic (-)epigallocatechin gallate, but not apigenin flavone, qualify as an antioxidant in apoptosis models caused by oxidative stress. Further work is necessary for elucidating the anti-apoptotic mechanisms of polyphenolic catechins.

• Journal of Korean Orthopaedic Sports Medicine
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• v.3 no.1
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• pp.87-91
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• 2004

Purpose: The purpose of this study is to investigate the incidence and patterns of fractures occurred in Inline skating accident. Materials and Method: We evaluated 20 patients, 20 cases(from september 2002 to August 2003) with fractures occurred during Inline skating. The incidence, sex, age, fracture site, associated injuries, causes of Inline skating injuries were analysed. The cases were male in 18(90$\%$), and female in 2(10$\%$). The most common distribution of age was in twenties and thirties. Result: The patients(12cases 60$\%$) with upper extremity fracture were more common than patients(8cases 40$\%$) with lower extremity fracture. Patients who had fracture in ankle were 35$\%$(7cases), forearm 20$\%$(4cases), wrist 20$\%$(4cases), elbow 15$\%$(3cases), thigh 5$\%$(1cases). According to the The Lauge-Hansen classification in ankle fractures there were four patients of supination-external rotation type, two patients of supination-abduction type, and 1 patient of pronation-external rotation type. In forearm and hand fractures, there were three distal radius fractures, one radio-ulnar shaft fracture, 2 scaphoid fractures, and two meta-carpal fractures. In elbow fractures, there were two supracondyle fractures, and one lateral condyle fracture. There were three epiphyseal plate injuries (Salt-Harris type II) in children, and all of them were treated by conservative method. Six fractures were intra-articular fractures. The most common associated injury was contusion(8cases 42.1$\%$). The number of patients who only rode Inline skating less than 3months(8cases 40$\%$) was the greatest. The number of non-contact injury(14cases, 70$\%$) in Inline skating was more than contact(6cases,30$\%$) injury. 11cases(55$\%$) had operative treatment, and 9cases(45$\%$) had conservative treatment, and there was not any complication. The more detailed study is required since the materials were only limited to fracture patients, and the follow up period was short. Conclusion: The most common age for fracture in Inline skating was in twenties, and thirties, and ankle was the most common fracture site.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.31 no.1
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• pp.4-10
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• 2022

A lack of space can be a key challenge when restoring lower anterior teeth using implants, especially for proper implant placement and the limitation on suitable implant selections. Moreover, depending on the shape of the prosthetic, the adjacent teeth and bone around the implant can also have a significant impact, while in certain cases, the implant can have a detrimental effect on the surrounding bone. Therefore, this case series highlights how variations in the subgingival contour can produce different results for the biology of the marginal bone around an implant and the interproximal bone of the adjacent teeth.