• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.128-128
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• 2018

최근 디스플레이 기술은 보다 가볍고, 얇고, 선명한 스마트 형태로 발전되고 있다. 특히 스마트산업의 성장으로 터치스크린패널(Touch Screen Panel, TSP)을 사용하는 기술이 다양해짐에 따라 더 높은 감도와 해상도를 달성하기 위한 핵심기술이 필요한 실정이다. TSP는 저항막 방식, 정전용량 방식, 적외선 방식, 초음파 방식 등 다양한 방식이 있다. 그 중 정전용량방식 터치 패널 (Capacitive type touch panel, CTTP)은 다른 유형에 비해 빠른 반응속도 및 멀티 터치 기능 등의 이점을 가지고 있기 때문에 연구의 초점이 되고 있다. 이를 실현하기 위해서 CTTP은 가시광영역의 높은 투과율과 낮은 비저항을 필요로 하기 때문에 박막의 초 슬림화 및 고 결정화도가 선행되어야만 한다. CTTP에 사용되는 투명전극 소재 중에서 40%의 비중을 차지하고 있는 ITO박막은 내구성과 시인성이 좋으나 생산 비용이 비싸다는 단점이 있다. 한편, 반응성 스퍼터링은 기존에 단일 소결체를 사용한 DC마그네트론 스퍼터링법보다 높은 증착률과 낮은 생산 비용으로 초박막을 만들 수 있다는 장점을 가진다. 본 실험에서는 In/Sn (2wt%) 금속 합금 타깃을 사용한 반응성 스퍼터링법을 이용하여 기판 온도 (RT 및 $140^{\circ}C$)에서 두께 30 nm의 In-Sn-O (ITO)박막을 증착하고, 대기 중 $140^{\circ}C$ 온도에서 시간에 따라 열처리한 후 박막의 물성을 관찰하였다. 증착 중 기판 가열을 하지 않은 ITO 박막의 경우, 열처리 시간이 증가함에 따라 비저항은 감소하였고, 홀 이동도는 현저하게 증가하였으며 캐리어 밀도에서는 별다른 차이가 없었다. 이를 통해 비저항의 감소는 캐리어 농도보다는 결정화를 통한 이동도의 증가와 관련 있다는 것을 확인할 수 있었다. 열처리 시간에 따른 박막의 핵 생성 및 결정 성장은 투과 전자 현미경(TEM)으로 명확하게 확인하였으며, 완전 결정화 된 박막의 grain size는 300~500 nm로 확인되었다. 기판온도 $140^{\circ}C$에서 증착한 박막의 경우, 후 열처리를 하지 않은 상태에서도 이미 결정화 된 것을 확인할 수 있었으며, 후 열처리 시에도 grain size에는 큰 변화가 없었다. 이는 증착 중에 박막의 결정화가 이미 완결된 것으로 판단된다. 또한, RT에서 증착한 박막의 경우에는 후 열처리 초기에는 산소공공등과 같은 결함들의 농도가 감소하여 투과율이 증가하였으나 완전한 결정화가 일어난 후에는 투과율이 약간 감소한 것을 확인할 수 있었다. 이는 결정화 시 박막의 표면 조도가 증가하였고 이로 인해 빛의 산란이 증가하여 투과율이 감소한 것으로 판단된다. 이러한 결과로 반응성 스퍼터링 공정으로 제조한 ITO 초박막은 후열처리에 의한 완전한 결정화를 이룰 수 있으며, 이를 통해 얻은 낮은 비저항과 높은 투과율은 고품질 TSP에 적용될 가능성을 가진다고 판단된다.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.565-575
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• 2010

Background: Various decellularization methods have been studied in order to develop tissue graft which is less immunogenic and more durable. This study was performed to investigate the physico-dynamic and histological effect of trypsin pretreatment on decellularization protocols. Material and Method: Two groups of bovine pericardium specimen each underwent decellularization process based on SDS and Triton X-100 or N-lauroylsarcosinate and Triton X-100. Two more groups additionally underwent pretreatment with 0.1% Trypsin/0.1% EDTA. After decellularization process, mechanical tensile strength was tested, then biomechanical test of permeability and compliance was tested before and after fatigue test. Light microscopy and electron microscopy was performed to observe histological findings. Result: There was no difference in mechanical tensile strength between groups, but permeability and compliance was decreased in trypsin pretreated groups. Light microscopic and electron microscopic findings revealed damage of the extracellular matrix in trypsin pretreated groups and in groups which underwent the fatigue test also. Conclusion: Trypsin pretreatment in decellularizing process of bovine pericardium damages extracellular matrix and increases permeability and compliance of the bovine pericardium, but did not decrease tensile strength. Further studies are needed to use enzymatic treatments in decellularization protocols.

• Applied Microscopy
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• v.32 no.3
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• pp.291-301
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• 2002

The present study was performed to compare the morphological differences of flight muscles among 3 species from insects (Xylocopa appendiculata circumvolans Smith, Davidins lunatus B. and Serrognathus platymelus castanicdor M.) by investigating ultrastructural observation and stereological analysis. Xylocopa appendiculata circumvolans Smith has the most flight hours. In addition, the number and arrangement of mitochondria and the structure of sarcomere were similar to those of vertebrates. However sarcomere structure of Davidins lunatus B. was irregular and the sarcomere length was longer than that of Xylocopa appendiculata circumvolans Smith. In Serrognathus platymelus castanicdor M. which has the least flight hours, the length of sarcomere appeared longer than that of Davidins lunatus B. In results of stereological analysis, Serrognathus platymelus castanicdor M. had the highest volume density of myofibrils in all species. The volume and numerical density of mitochondria and the volume density of sarcoplasmic reticulum were highest Xylocopa appendiculata circumvolans Smith and Davidins lunatus B. respectively. This study suggests that the flight hours and flight pattern by different ecological habitats may cause the morphological changes of flight muscle.

• Applied Microscopy
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• v.41 no.4
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• pp.277-284
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• 2011

This study was conducted to determine the antiseptic effect of stabilized chlorine dioxide (S-$ClO_2$) on muscle tissue of rats. Skeletal muscle of 8-week old Sprague-Dawley rats was used. Light and transmission electron microscopic findings were observed in the control group, which was not treated with stabilized chlorine dioxide, and in the experimental group, which was treated with a stabilized chlorine dioxide powder in aqueous solution. According to the LM and TEM observations, the day 1 control group showed the initiation of endomysium collapse resulting in an unclear boundary of muscle fibers, and partial collapse of the mitochondrial membranes. All endomysium had collapsed, and bacteria were observed among muscle fibers in the day 2 and later groups. Shapes of muscles were not distinguishable in day 3 or later groups. In contrast, the day 1 and 3 experimental groups revealed detailed structure of typical muscles, but partial collapse of the mitochondrial membranes was observed in the day 3 and later groups. Subsequently, connective tissues collapsed and structures in the shape of concentric circles were observed. In summary, the day 1 control group showed the initial collapse of tissues, and shapes were not distinguishable in the day 3 and later groups because most of the tissues had collapsed. In contrast, the day 3 experimental group showed partial collapse, but the overall shapes of muscles were maintained as time went on, confirming the antiseptic effect of stabilized chlorine dioxide on muscles.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.162-167
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• 1999

GaN epilayers deposited by the OMVPE method on sapphires with 3 different surface orientations were investigated by TEM and their difference in mucrostructure were compared with each other. GaN epilayers were grown on the all three kinds of sapphire substrates; however, the best interfacial state and crystallinity were observed in the specimen using a {0001} substrate The density of defects in GaN epilayers on {0001} substrates was also less than others. No buffer layer was found at the interfaces of all the specimens; however, it was observed that the region which shows lattice distortion at the interface was only a few nonameter wide. Accordingly, TEM investigation revealed that GaN epilayers having some internal defects could be grown on sapphire {1120} and {1102} planes without a buffer layer, and the hetero-epitaxial GaN films were obtained from the specimen using {0001} substrates with the microstructural point of view.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.87-94
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• 2015

High voltage pulsed electric fields (PEF) treatment is one of the more promising nonthermal technologies to fully or partially replace thermal processing. The objective of this research was to investigate the microbial inactivation mechanisms of PEF treatment in terms of intra- and extracellular changes in the cells. Saccharomyces cerevisae cells treated with PEF showed cellular membrane damage. This resulted in the leakage of UV-absorbing materials and intracelluar ions, which increased with increasing treatment time and electric fields strength. This indicates that PEF treatment causes cell death via membrane damage and physical rupture of cell walls. We further confirmed this by Phloxine B staining, a dye that accumulates in dead cells. Using scanning and transmission electron microscopy, we observed morphological changes as well as disrupted cytoplasmic membranes in PEF treated S. cerevisae cells. In addition, PEF treatment led to damaged chromosomal DNA in S. cerevisiae.

• Research in Plant Disease
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• v.8 no.3
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• pp.189-192
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• 2002

Mummy disease has been observed for a long time in the button mushroom, Agaricus bisporus farms in Korea, and severe mummy disease occurred on “Shinryung” mushroom, A. blazei recently. Typical symptoms of mummy disease were observed on the mushroom-cultivation beds infected ; tilted caps of mushrooms, browning and lignified internal tissue of stipe, overdevelopment of mycelium around the base of the stipe, and mummified mushrooms. Electron micrographs prepared from internal tissue of stripe of the diseased mushrooms showed that many bacterial cells present inside hyphal cells of the diseased mushroom, which is one of the characteristics of mummy disease reported previously, Survey in Buyo, Chungnam showed that mummy disease occurred at 55% and 83% frequency on bottom mushroom (brown strain) and “Shinryung” mushroom cultivation during year 2000. It indicates that mummy disease is one of the major diseases for the mushrooms cultivation.

• Journal of Aquaculture
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• v.20 no.3
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• pp.173-177
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• 2007

An experiment was performed to obtain cryopreservation techniques of starry flounder (Platichthys stellatus) sperm. Milt obtained from 24 males were cryopreserved using two diluents, artificial seminal plasma (ASP) and Stein's solution (SS) with three cryoprotectants, dimethyl sulfoxide (DMSO), methanol, and glycerol concentrated from 5% to 20%. Post-thaw sperm activity (motility and/or speed) revealed the highest in 10% DMSO and 15% methanol in ASP and SS as diluent. Motility and speed of cryopreserved sperm were decreased according to increase of glycerol concentration. To conclude, DMSO was a better cryoprotectant than methanol or glycerol for cryopreservation of starry flounder sperm. Glycerol was incongruent cryoprotectant because of toxic to starry flounder sperm. Most cryopreserved spermatozoa without cryoprotectant showed the enlarged head with granulated chromatin and ruptured plasma membrane by freezing and thawing injuries compared with unfrozen normal spermatozoa.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.207-211
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• 1999

$Si/Si_{1-x}Ge_x$ MODFET structures, incorporating linearly-graded buffer layers have been grown by GaS Source Molecular Beam Epitaxy. The growth temperature of the graded layers has not significantly changed the distribution of misfit dislocation. However, the surface undulation and surface defects were increased with increasing growth temperature. In $Si/Si_{1-x}Ge_x$ MODFET structures, the densities of misfit dislocations near the Si-active layers were considerably reduced in comparison with the region of graded layers. The electron mobility of $Si/Si_{1-x}Ge_x$ MODFET structure has increased with lowering the growth temperature.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.207-207
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• 2003

최근 광촉매 재료로 각광받고 있는 TiO$_2$는 band gap 에너지가 3.0-3.2eV로 자외선 영역과 일부 가시광선 영역에서 활성을 갖는 것으로 알려져 있다. 따라서 용액 중에 결정화 및 안정화 되어있는 TiO$_2$의 band gap 에너지를 낮춘다면 가시광 영역의 광반응을 얻을 수 있다. 이에 본 연구는 G. Sato등이 제안한 방법으로 TiO$_2$ sol을 제조할 때 band gap 에너지를 낮추고자 천이 금속원소를 첨가하여 복합 및 담지된 TiO$_2$계 복합 sol을 합성하고자 하였다 출발원료는 TiC1$_4$를 가수분해하여 제조한 TiOCl$_2$에 천이금속원소인 V, Cr, Fe, Ni, Nb 등의 chloride 화합물을 첨가하여 중화 및 세척과정을 거친 후, 과산화수소수에 용해하여 전구체 용액인 titania peroxo용액을 제조하였다 제조된 전구체 용액은 온도와 시간을 변수로 각각 열처리하여 TiO$_2$계 복합 sol을 합성하였다. 제조된 시편은 X-선 회절 분석, 투과전자현미경, particle size analyzer, ζ-potential analyzer 및 UV-VIS Spectrometer 통을 이용하여 천이금속 첨가에 따른 TiO$_2$계 복합 sol의 형성과정과 특성변화를 관찰하였다.