• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 추계학술발표회 초록집
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• pp.67-67
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• 2001

The structure zone model has been used to provide an overview of the relationship between the microstructure of the films deposited by PVD and the most prominent deposition condition.s. B.AMovchan and AV.Demchishin have proposed it firstls such model. They concluded that the general features of the resulting structures could be correlated into three zones depending on $T/T_m$. Here T m is the melting point of the coating material and T is the substrate temperature in kelvines. Zone 1 ($T/Tm_) is dominated by tapered macrograins with domed tops, zone 2 ($O.3) by columnar grains with denser boundaries and zone 3 ($T/T_m>O.5$) by equiaxed grains formed by recrystallization. J.AThomton has extended this model to include the effect of the sputtering gas pressure and found a fourth zone termed zone T(transition zone) consisting of a dense array of poorly defined fibrous grains. R.Messier found that the zone I-T boundary (fourth zone of Thorton) varies in a fashion similar to the film bias potential as a function of gas pressure. However, there has not nearly enough model for explaining the change in morphology with crystal orientation of the films. The structure zone model only provide an information about the morphology of the deposited film. In general, the nucleation and growth mechanism for granular and fine structure of the deposited films are very complex in an PVD technique because the morphology and orientation depend not only on the substrate temperature but also on the energy of deposition of the atoms or ions, the kinetic mechanism between metal atoms and argon or nitrogen gas, and even on the presence of impurities. In order to clarify these relationship, AI and Mg thin films were prepared on SPCC steel substrates by PVD techniques. The influence of gas pressures and bias voltages on their crystal orientation and morphology of the prepared films were investigated by SEM and XRD, respectively. And the effect of crystal orientation and morphology of the prepared films on corrosion resistance was estimated by measuring polarization curves in 3% NaCI solution.

• Applied Microscopy
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• 제26권1호
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• pp.79-93
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• 1996

The differentiation of nail matrix and fine structure of matrix cells were studied with light and electron microscope using specimens from nails of thumb finger in Korean fetuses 14 to 24 weeks old. Fetal nail matrix consisted of two horizontal layers, thicker ventral and thinner dorsal matrices, originating from invagination of epidermis in proximal nail field. Matrix being generally thicker in its distal region than the apex became gradually thickened with increase of the fetal age. Each matrix consisted of single layer of basal cells and multiple layers of squamous cells which are arranged close to and parallel to the central axis of the nail mairix. The process of keratinization of fetal nail matrix was noted to be occured concurrently in the ventral and dorsal matrices along the central axis of matrix toward distal and dorsal direction. Squamous cells became matured with accumulation of tonofilaments, increase of keratohyalin granules, discharge of membrane coating granules, and narrowing of intercellular spaces, thickening of plasma membrane and finally being transformed into horny cells of nail plate. Horny cells of nail plate filled with fibrous elements in the electron dense amorphous substance. These findings of keratinization process of fetal nail matrix appeared to be similar to those of keratinization in epidermis and inner root sheath of the hair. In the nail matrix, however, corresponding region to the keratogenous zone of growing hair follicle was not observed. Vacuolated squamous cells of nail matrix seen on light microscopy was considered to be artefactual product, but squamous cells with condensed small nuclei rarely found adjacent nail plate was considered to be one of the squamous cells with unknown function. Proximal end of nail plate was observed on dorsal surface of nail field distal to the proximal nail fold at 14 and 16 weeks old human embryos. Proximal prolongation of the proximal end of nail plate was occured with advancing fetal age and afterward 21 weeks nail plate invaded into nail matrix. Melanin granule containing cells and Merkel cells were present only on the basal layer of dorsal nail matirx.

• Tuberculosis and Respiratory Diseases
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• 제41권3호
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• pp.248-261
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• 1994

연구배경 : Lectin은 탄수화물의 특정한 당잔기에 높은 친화성과 특이성을 가지므로 이러한 lectin-sugar 상호작용을 이용하여 사람 폐결핵결절에서 이를 구성하는 주된 성분인 건락성 괴사 상피양세포, 림프구 및 섬유층에 존재하는 탄수화물의 종류와 분포에 대해 알아보고자, 본 연구를 실시하였다. 방법 : 사람 폐결핵 절제 조직에서, 13종의 lectin을 사용하여 조직화학염색을 시행하였다. 결과: 1) 건락성 괴사부에서 BS $I-B_4$는 모든 구성성분에서, BS I는 변연부에 있는 일부의 세포성분을 제외하고 나머지 구성성분 모두에서 음성반응을 나타내었다. 그러나 나머지 lectin들은 건락성 괴사부에서 다양한 형태의 렉틴결합반응을 나타내었다. 2) 상피양세포들은 세포질에서의 반응 양상에 따라 크게 세 군으로 나눌 수 있었다. 첫째, DBA, UEA I 및 LCA는 대부분 중등도 이상의 강한 양성반응을 나타내었다. 둘째, WGA, s-WGA, PNA, SBA, VVL, ECL, PHA-L 및 PHA-E는 세포에 따라 다양한 형태의 반응양상을 나타내었다. 셋째, BS I 및 BS $I-B_4$는 음성반응을 나타내었다. 상피양세포의 세포막에 대한 결합반응을 살펴보았을 때, 첫째, ECL, PHA-L 및 PHA-E는 대부분 강한 양성반응을 보여주었다. 둘째, WGA, s-WGA 및 PNA는 세포에 따라 양성 및 음성반응이 혼재하는 양상을 나타내었다. 셋째, BS I, BS $I-B_4$, UEA I, DBA 및 VVL은 음성반응을 나타내었다. 3) 상피양세포사이물질들은 건락성 괴사부의 세포사이물질에 대한 lectin 결합 양상과 유사한 반응 양상을 나타내었다. 4) WGA, ECL, PHA-L, PHA-E 및 LCA들은 림프구에 강한 양성반응을 나타내었다. 5) SBA는 건락성 괴사부를 둘러싸는 섬유층의 외측에 위치하는 혈관 내피층에서 대체로 양성반응을 보였으나, 섬유층내의 혈관 내피층에서는 대체로 음성반응을 나타내었다. 6) PNA는 섬유층의 외측지역에서 양성반응을 나타내었지만 그와는 대조적으로 내측지역의 세포사이물질에서 음성반응을 나타내었다. 결론 : 이상의 결과와 같이, 렉틴결합특성을 이용한 조직화학적 연구는 사람 폐결핵 결절의 여러 성분들에 존재하는 복합당질의 종류, 특성 및 분포, 그리고 연결핵결절 형성과정 동안에 일어나는 복합당질 조성의 변화에 관한 유용한 정보를 제공해 주었으며, 이러한 결과들은 결핵결절의 병리학적 연구에 도움이 될 것으로 사료된다.

• International Journal of Industrial Entomology and Biomaterials
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• 제40권1호
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• pp.28-32
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• 2020

Recently, many studies have been undertaken on the wet spinning and electrospinning of silk because wet-spun fibers and electrospun webs of silk can be applied in the biomedical and cosmetic fields owing to the good biocompatibility of silk. The rheological properties of silk solution are important because they strongly affect the spinning performance of the silk solution and the structures of resultant fibrous materials. Therefore, as a preliminary study on the effect of solvent composition on the rheological properties of silk fibroin (SF) solution and structure of the resultant film, in the reported work, methanol was added to the SF formic acid solution. A small amount of methanol (i.e. 2%) added to the SF formic acid solution significantly altered the rheological properties of the solution: its shear viscosity increased by 10 folds at low shear and decreased on increasing the shear rate, demonstrating shear thinning behavior of the SF solution. Dynamic tests for the SF solution indicated that the addition of 2% methanol altered the viscous state of the SF formic acid solution to elastic. However, the molecular conformation (i.e. β-sheet conformation) of the regenerated SF film cast from formic acid remained unchanged on the addition of 2% methanol.

• 센서학회지
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• 제29권2호
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• pp.89-92
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• 2020

Polytetrafluoroethylene (PTFE) fibers are widely used in the textile industry, filter media, membrane distillation, electronic appliances, and construction. In this study, PTFE-polyethylene oxide (PEO) fibrous membranes were fabricated by emulsion electrospinning; subsequently, pure PTFE nanofibers were obtained via sintering. PTFE-PEO electrospinning solutions were prepared using different weight ratios to determine the optimized condition. As the ratio of the PEO increased, the fiber structure improved. Scanning electron microscopy and Fourier-transform infrared spectroscopy observations indicate that PEO is removed and PTFE fused gradually to form bonds among them during sintering. The obtained pristine PTFE membrane demonstrated hydrophobicity at 143.6° water contact angle and oleophilicity at 0° oil contact angle, which is known to be utilized for oil/water separation. A simple separation experiment was performed to remove oil droplets from water. The PTFE membrane exhibited good chemical stability and a high surface-area-to-volume nanofiber ratio. These excellent properties suggest that it is applicable to oil/water separation in harsh chemical environments.

• 한국재료학회지
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• 제24권12호
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• pp.663-670
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• 2014

Diameter-controlled tin oxide nanofibers have been successfully prepared using electrospinning and a subsequent calcination process; their diameters, morphologies, and crystal structures have been characterized. The diameters of the as-spun nanofibers can be decreased by lowering the concentration of a polymer and a tin precursor in the electrospinning solution because of the decrease in the solution viscosity. The crystal structure of the nanofibers calcined at various temperatures from $200^{\circ}C$ to $800^{\circ}C$ has been proved to be the tetragonal rutile of tin oxide; crystallinity is improved by increasing the temperature. However, nanofibers with lower concentrations of tin precursor do not maintain their fibrous structures after calcination at high temperatures. In this study, the effect of the relationship between the precursor concentration and the calcination temperature on the diameter and the morphology of the tin oxide nanofiber has been systematically investigated and discussed.

• 한국재료학회지
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• 제23권9호
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• pp.531-536
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• 2013

This paper investigates the effect of prolonged high temperature exposure on concentric laminated $Al_2O_3-ZrO_2$ composites. An ultrafine scale microstructure with a cellular 7 layer concentric lamination with unidirectional alignment was fabricated by a multi-pass extrusion method. Each laminate in the microstructure was $2-3{\mu}m$ thick. An alternate lamina was composed of 75%$Al_2O_3$-(25%m-$ZrO_2$) and t-$ZrO_2$ ceramics. The composite was sintered at $1500^{\circ}C$ and subjected to $1450^{\circ}C$ temperature for 24 hours to 72 hours. We investigated the effect of long time high temperature exposure on the generation of residual stress and grain growth and their effect on the overall stability of the composites. The residual stress development and its subsequent effect on the microstructure with the edge cracking behavior mechanism were investigated. The residual stress in the concentric laminated microstructure causes extensive micro cracks in the t-$ZrO_2$ layer, despite the very thin laminate thickness. The material properties like Vickers hardness and fracture toughness were measured and evaluated along with the microstructure of the composites with prolonged high temperature exposure.

• 대한소아치과학회지
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• 제10권1호
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• pp.25-33
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• 1983

With electron microscope, author studied on the pulp structure of human primary tooth in shedding stage. Non-carious human primary molar teeth were selected for this study. Using standard methods, specimens were sectioned and examined by light and electron microscope, The results were as follows; 1. In coronal pulp, odontoblasts were replaced by multinucleated odontoclasts, which contained a large number of mitochondria of varying shape and vacuoles in cytoplasm. Where odontoclasts were in contact with tooth surface, the characteristic ruffled border and clear zone were observed. 2. Fibrous tissue with plentiful collagen fibers and fibroblasts was observed adjacent to the dentin in the pulp. Fibroblast contained a number of mitochondria and well-developed rough-surfaced endoplasmic reticulum. 3. Inflammatory cells were observed in the pulp and active fibroblasts could be seen between inflammatory cells. In many cases, cervical epithelium proliferated toward absorbed area. 4. Inflammatory cells consisted of a number of lymphocytes, polymorphonuclear leukocytes, plasma cells and macrophages. Macrophage containing lysosomes in digestive state or phagocyting PMN could be seen. 5. In the primary molar of delayed root resorption, odontoblast layer, zone of Weil and cell-rich zone could be seen at roof of pulp chamber and odontoblast in this area cont과ained some lipid droplets.

• Restorative Dentistry and Endodontics
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• 제9권1호
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• pp.107-114
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• 1983

The purpose of this study was to observe the effect of cleansing action of irrigation solutions which was 3% $H_2O_2$ and 5% NaOCl, and 15% EDTA solution on the root canal wall. After treatment with the irrigant, each sample was dehydrated, and coated with 200~250${\circ}$A of gold, and observations were made with the use of scanning electron microscope. The results were as follows: 1. In the root canal walls irrigated with 3% $H_2O_2$ and 5% NaOCl solution without instrumentation after extirpation through barbed broach, the predentin of root canal wall was found scarely affected, and the wall was shown retaining network structure and fibrous organic matters. 2. When 15% EDTA was applied as irrigants for 60, 90 and 120 seconds after instrumentation, there was no signigicant difference of the cleansing effect of the elapsed times which were 90 and 120 seconds on the root canal wall, but in the applied time which was 120 seconds, the canal wall was the cleanest. Therefore it was thought that the most suitable application time of 15% EDTA as the irigants was 120 seconds.

• 대한물리치료과학회지
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• 제9권3호
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• pp.161-170
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• 2002

knee injuries are among the most common problems confronting patients, physical therapist and physicians. since the bony structure provides little stability, the soft tissues are required to withstand high forces, often resulting in tissue overload and injury immobilization of the knee in the presence of a hemarthrosis usually leads to proliferation of intraarticular connective tissue adhesions and pint fibrosis. the physical basis of treating scar tissue is early controlled motion. the management of the knee with increased instability is to strengthening the muscles to properly treat an soft tissue injuries, physical therapist should know about the anatomic structures and biomechanical function of the knee joint, in this review article, we discuss the physiologic properties of soft tissue, biomechanical observation in fibrous connective tissue, managing soft tissue contractures, principles in treating scar tissue and treatment of the knee with increased instability.