• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.185-185
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• 2013

최근 의료 영상 센서는 급속도로 발전을 이룩하여 미세 병변의 위치와 그 크기를 진단하는 데에 많은 이용이 되고 있다. 하지만 기존 flat panel형태의 의료영상 센서는 인체의 굴곡으로 인한 영상 왜곡으로 발전의 한계에 이르고 있는 실정이다. 이 영상 왜곡으로 인한 오진은 환자에게 불필요한 피폭, 수술적 요법, 약물치료 등 환자에게 치명적인 의료사고를 일으킬 수 있다. 이러한 한계를 극복하기 위하여 flexible substrate을 이용한 투명전극들이 의료영상 센서로서의 적용을 연구 되어 졌다. IZO, ITO, FTO 등의 투명전극들 중 Indium Tin Oxide(ITO)는 다른 전극에 비해 높은 투명도와 낮은 저항으로 인하여 다양한 부분에서 널리 이용 되고 있다. 그러나 ITO를 flexible substrate로 적용 시 불충분한 resistivity와 기계적 강도를 지니고 있으며, 유연성을 위해 전극 재료의 두께를 감소시키면 전도성의 문제를 일으키는 단점이 있는 것으로 알려져 있다. 이러한 문제점을 보완 및 해결하기 위하여 본 연구에서는 sputtering magnetron system를 이용하여 polyethylene terephthalate(PET) substrate 위에 ITO을 증착함으로써 전기적 특성을 알아보았다. PET 필름의 크기를 55 절단하였고 증착 온도는 고온에서 수축하는 PET 필름의 물성을 고려하여 $23^{\circ}C$로 설정 하였다. 가스의 분압 비를 Ar는 50ccm으로 고정하고 O2의 비율을 각각 0, 0.2, 0.4, 0.8, 1ccm으로 나눈 후, 비율에 따라 각각 30, 60, 90sec간 sputtering 증착을 하였다. 또한 각각 30, 60, 90sec간 sputtering 증착하여 O2 유량과 sputtering 증착 시간의 변화에 따른 ITO의 전도특성과 유연성에 대한 전도특성을 측정하였다. 유연성을 측정하기 위해선 bending 각도를 각각 $0^{\circ}$ $30^{\circ}$, $45^{\circ}$, $60^{\circ}$로 구부린 후, Two-point probe를 이용하여 변화된 저항을 통해 ITO의 전기적 성질의 변화를 측정 하였다. 측정결과 flexible ITO substrate의 전도특성은 sputtering 증착시간이 증가할수록 저항 값이 낮아지는 것을 확인하였지만, O2 유량이 증가 시 저항이 낮아지다가 다시 증가하는 결과를 알 수 있었다. 본 연구에서는 Ar:O2의 50:0.8의 조건에서 90sec동안 sputtering 증착한 ITO가 131 ${\Omega}/cm^2$의 저항 값이 측정 되었고 다른 조건에서는 164 ${\Omega}/cm^2$에서 4.7 $k{\Omega}/cm^2$까지 저항변화를 가져 Ar:O2의 50:0.8의 조건이 최적화에 좋은 조건이라 판단하였다. 또한 50:0.8의 조건의 ITO의 경우 bending test시에서도 131 ${\Omega}/cm^2$에서 316 ${\Omega}/cm^2$ 정도의 안정적인 저항변화를 가지는 반면 다른 조건에서는 128 ${\Omega}/cm^2$에서 6.63 $k{\Omega}/cm^2$까지의 변화를 나타나 기계적 형상변화에도 분압비가 영향을 주는 것을 확인 할 수 가 있었다. bending 각도에 따른 저항의 변화를 측정하였을 시, 각도 변화에 따라 중심부의 저항 값이 $60^{\circ}$에서 가장 높은 변화가 나타나 전기저항이 높아진 원인을 찾기 위해 Scanning Electron Microscope (SEM)촬영을 한 결과 저항값이 높아짐에 따라 ITO의 압축응력이 작용하는 부근에 Crack이 발생함을 알 수 있었다. 이러한 결과로 flexible ITO substrate의 Crack발생률을 최소화 시키고 bending시 전도성을 유지하기 위해서는 가스의 유량 최적화가 flexible substrate의 기계적형상변화에 대한 ITO의 내구성을 향상시킬 수 있는 해답이 될 것으로 사료된다.

• Journal of Life Science
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• v.18 no.4
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• pp.509-514
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• 2008

Tremendous natural product extracts were used as a herb medicine remedy or therapy for centuries. Because these extracts have various biological activities, we examined the effects of Gryllotalpa orientalis extract for anti-oxidant and anti-inflammation activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing ability of plasma (FRAP), hydroxy radical scarvenging and cyclooxygenase-2 promoter assays. Gryllotalpa orientalis extracts were prepared from solvents such as distilled water (DW), dimethyl sulfoxide (DMSO), ethanol and methanol. The results showed that Gryllotalpa orientalis extracts have potent DPPH (methanol extract), FRAP (DW extract) and hydroxy radical scavenging (DW and methanol extracts) activity than any other extracts used. A significant inhibition of cyclooxygenase-2 (Cox-2) promoter activity was detected in the presence of DMSO extract or ethanol extract. Collectively, the present results suggested that Gryllotalpa orientalis extract could be used for anti-oxidant and/or anti-inflammation agent for human or agricultural purposes.

• Korean journal of food and cookery science
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• v.13 no.3
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• pp.259-265
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• 1997

The main purpose of this research is to provide a basic knowledge of Kimchi and to improve elementary school childrens' Kimchi intake. We researchers have done statistical analyses of 808 questionnaires completed by elementary school children and their mothers on their awareness of and preference for Kimchi. The results were as follows: About 80.2％ of the children regarded Kimchi as one of our nutritious and traditional foods, and 83.8％ of the subjects had an affirmative opinion of Kimchi intake. The most well known Kimchi is as follows: Baechu Kimchi, Kkaktugi, Nabak Kimchl, Chonggak Kimchi, Saaennip Kimchi and Buchu Kimchi. The children preferred the peculiar and refreshing taste of Kimchi. Their preference of Kimchi is in the following order: Baechu Kimchi, Skaktugi, Chonggak Kimchi, Nabak Kimchi and Oi Sobagi. And the children also preferred the stems of the cabbage. The children preferred properly fermented and freshly prepared Kimchi. Their favorite ingredients were red pepper powder, Korean radishes, pickled anchovies, sesame leaves, garlic and scallions. The children wanted Kimchi that is less hot and more sweet. The ingredients children wanted to add to Kimchi are pears, cuttlefish, oranges, apples and cucumbers.

• Restorative Dentistry and Endodontics
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• v.30 no.1
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• pp.22-30
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• 2005

The purpose of this study was to compare the effect of surface sealing materials on microleakage and surface roughness in Class V composite restorations. Twenty five standardized Class V cavity preparations were made on the facial surface of human premolars and were randomly assigned to 5 groups. The teeth were restored with Z-250 after applying Single Bond. Following 7 days storage in distilled water at $37^{\circ}C$, the restorations were sealed as following systems : No sealing ; Single Bond Adhesive ; Biscover ; Fortify ; Optiguard. Then, toothbrush abrasion test was conducted using a wear testing machine. Surface roughness was measured by means of profilometer before and after toothbrushing and the results were statistically analysed by using a paired t-test and ANOVA. The bonded interfaces and the changes of surface roughness were examined by SEM. For microleakage test, specimens were stained in a $2\%$ methylene blue solution, then longitudinally sectioned and analyzed for leakage at occlusal and cervical interfaces using stereomicroscope. The results were statistically analysed by using a Kruskal-Wallis and Mann-Whitney U test. Surface roughness was increasing in all groups after toothbrushing, but no statistically significant differences. In SEM observation, surface sealant was partially retained and partially detached in bonded interfaces. Especially, microgap was identified in cervical margins. In microleakage test, there was better seal in the enamel region and a significant difference between groups at occlusal margin. Control group and Single Bond group had significantly better marginal seal at enamel margin than cervical margin.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.93-101
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• 2010

When doing underground excavation works for the purpose of constructing large underground structures for a building in the limited space in downtown area, the stability of the adjacent ground must be top priority, and to accomplish this, it is essential to review the retaining wall construction carefully. H-Pile, which has been mainly used as a stress-carrying material in temporary earth-retaining structures, is most likely to be abandoned after completion of the works for the basement exterior wall in relation to contiguous bored piles, so it will result in a waste of material. To improve this situation, Basement Composite Wall where H-Pile and basement wall are compounded, has been developed. This wall is being used most frequently in many local construction sites. In this study, five specimens are made in order to evaluate the shear resistance of the basement composite wall and tested. Test parameter is the composition ratio and wall thickness according to shear connectors. Test result shows that the shear strength is improved when the composite ratio is increased but the magnitude is not much. A formula, which considers the contribution of concrete, web of H-pile as well as flange' effect in calculation of shear strength of composite basement wall, is suggested and used to calculation of the strength of specimens. It is found that there is a good co-relation between test result and the calculated one by the formula.

• Polymer(Korea)
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• v.38 no.1
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• pp.54-61
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• 2014

Water-soluble sulfobetaine chitosan (SCs) was prepared for a blending film with Bombyx mori silk fibroin (SF) by reacting chitosan with 1,3-propanesultone. A series of SF/SCs blended films were successfully prepared by mixing aqueous solutions of B. mori SF and SCs. The SF/SCs blended films were examined through spectroscopic and thermal analysis to determine the morphological changes of SF in the SCs. The effects of the SF/SCs blend ratios on physical and mechanical properties were investigated to discover the feasibility of using these films as biomedical materials such as artificial skin and wound dressing. X-ray analysis showed good compatibility between the two biopolymers. The in vitro degradation behavior of the SF/SCs blended films was systematically investigated for up to 8 weeks in phosphate buffered saline solution at $37^{\circ}C$ and showed a mass loss of 46.4% after 8 weeks. All films showed no cytotoxicity by MC3T3-E1 assay. After 3 days of culture, the relative cell number on all the SF/SCs films was slightly lower than that of an optimized tissue culture plastic.

• Food Science and Preservation
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• v.14 no.2
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• pp.213-219
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• 2007

To develop an anti-dementia agent with potential therapeutic value in the protection of neuronal cells, we selected a water extract of Helianthus annuus seed for analysis. We measured acetylcholinesterase inhibitory activity in the extract, and analyzed the protective effect of the extract on neuronal cell death induced by hydrogen peroxide, or amyloid ${\beta}-peptide$, of SH-SY5Y neuroblastoma cells. The result showed that the extinct exerted protective effects of 83%, 72% and 53% respectively, on cell death induced by 100M, 200M, and 500M hydrogen peroxide. Also, when 50M of amyloid ${\beta}-peptide$ was added to the cells, the extract showed a protective effect (up to 80%) on cell death. Overall, the results showed that the H. annuus extract inhibited acetylcholinesterase activity in a dose-dependent manner, and the extract also strongly protected against cell death induced by hydrogen peroxide or amyloid ${\beta}-peptide$.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.57-57
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• 2019

본 연구는 관상 및 조경용으로 개발이 가능한 남방계 양치식물인 점고사리[Hypolepis punctata (Thunb.) Mett.]의 전엽체 증식 및 포자체 형성에 적합한 배양조건을 구명하고자 수행되었다. 무가온 온실에서 성숙한 포자엽을 채집한 후 포자를 기내에서 발아시켜 전엽체를 획득하였으며, 8주 간격으로 계대배양 하여 실험의 재료로 사용하였다. 배지종류에 따른 전엽체의 증식 및 형태형성을 확인하고자, 배양된 전엽체 0.3g을 메스로 잘게 다진 후, 농도를 1/4, 1/2, 1, 2배로 조절한 MS배지에 8주간 배양하였다. 이후 선발된 배지를 기준으로 sucrose, 활성탄, 질소급원의 농도를 조절하여 전엽체의 증식과 형태형성을 확인하였다. 그 결과, 1MS배지에서 전엽체의 생체중이 초기 접종량인 0.3g에 비해 10.7배 증가한 3.2g으로 가장 높은 증가율을 보였다. 형태관찰에서도 장정기의 형성이 관찰되었으며, 전엽체의 쿠션조직이 비교적 잘 발달하였다. 전엽체 증식에 가장 좋은 효과를 보인 1MS배지를 기준으로 sucrose의 농도를 0-4%로 달리하여 실험한 결과, 1%의 처리구에서 6.7g으로 가장 높은 생체중을 보였다. 활성탄의 농도를 0-0.8%로 첨가한 네 처리구 중에서는 0.8%의 처리구에서 14.2g으로 무처리구에 비해 생체중이 2배 이상 증가하였다. 전엽체의 형태 또한 정상적인 발달을 보였다. 질소급원의 비율을 30-120mM로 조절한 배지에서는 60mM의 처리구에서 4.9g으로 가장 높은 생체중을보였다. 이후 포자체 형성을 위한 최적의 토양조건을 구명하고자, 원예상토, 피트모스, 펄라이트 및 마사토의 비율을 달리하여 5종류의 배양토를 조성하였다. 혼합된 토양은 사각분($7.5{\times}7.5{\times}7.5cm$)에 충진 하였으며, 배양된 전엽체 1g을 증류수와 함께 10초간 분쇄한 다음 준비된 토양표면에 분주하여 재배하였다. 12주간의 재배 결과, 원예상토를 단용한 토양에서 포자체의 수가 포트당 250.0개로 가장 많이 형성되었으며, 포자체의 생육 또한 다른 처리구에 비해 우수한 결과를 보였다. 한편 피트모스가 혼합된 토양에서는 포자체가 형성되지 않았다. 따라서 점고사리의 전엽체 대량증식에 적합한 배지는 sucrose 1%와 질소급원의 농도를 60mM, 활성탄을 0.8% 첨가한 1MS배지로 판단되며, 포자체 대량생산을 위해서는 원예상토를 단용한 토양이 적합하다고 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.535-542
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• 2019

The purpose of this study was to obtain basic data necessary for making a nuruk salt by comparing and analyzing the ingredients of various nuruk salts, and to select a nuruk salt that meets the users' needs. We selected the types of nuruk as the ihwaguk, miinguk, baekguk, and koji to identify the characteristics of the nuruk, and then analyzed the chemical characteristics after manufacturing the nuruk salts under the same conditions of fermentation, such as material ratio and temperature. In the manufacture of nuruk salt, the pH level dropped from 6.2~6.5 before fermentation to 6.1~6.2 three days after fermentation. The Acidity increased from 0.16~0.18 before fermentation to 0.22~0.25 after fermentation and there was no difference between the nuruk. The sugar content has risen since fermentation, and nuruk salt made by koji showed the largest increase in the sugar content. The salinity of the nuruk salt was raised to 37~44 after fermentation from 30~32 before fermentation and indicated largest increase in nuruk salt made by koji. Organic acids of nuruk salt were detected in the order of acetic acid, oxalic acid, malic acid, lactic acid, and citric acid. The oxalic acid of the baekguk salt was found to be 0.77 mg/mL, 2.3 times more of the koji, and the succinic acid was also found to be the highest with 1.19 mg/mL. Malic acid, lactic acid, acetic acid, and citric acid were found to have the highest amount of koji salt at 0.29 mg/mL, 1.48 mg/mL, and 0.12mg/mL, respectively, making it a better taste to be soft than other nuruk salt.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.584-595
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• 2018

This study conducted direct shear test on about 290 sorts of materials such as sandy soil, clayey soil and gravely soil to present proper standard on shear strength of soil. Shear strength of soil in large scale tends to show that angle of internal friction increases as sand contents grow and it ranges $23.5^{\circ}{\sim}34.9^{\circ}C$ with cohesion of 2.0 kPa~15.7 kPa. Elastic modulus was visibly distinct by load, and which increased approximately 80% as vertical load grows. Angle of internal friction arranging $15.0^{\circ}{\sim}28.6^{\circ}$ on clayey soil decreased as clay contents rises and cohesion increase in regular scale. Elastic modulus tends to increase initial elastic modulus with almost same growing rate. While angle of internal friction on gravely soil indicates $29.9^{\circ}{\sim}36.7^{\circ}$ which hardly shows distinctive features. According to test in detail, cohesion of SW (well-graded sand), SP (poorly-graded sand), SC (clayey sand) and SM (silty sand) indicates value by 94%, 78% and 59% comparing to SC, SW and SP respectively. Angle of internal friction of ML (low-liquid limit silt) and CL (low-liquid limit clay) appears almost same features, and MH (high-liquid limit silt) despite of 88% value of ML. Cohesion among them varies with similar growing rate.