• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1347-1348
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• 2007

In this paper, ITO gate electrode surface was modified using $O_2$ plasma and organic gate insulating layers were deposited on the ITO surface using plasma polymerization technique. In order to investigate the influence of the plasma coupling method and plasma conditions on the plasma polymerized methyl methacrylate (ppMMA) thin film properties, inductively coupled (ICP) and capacitively coupled plasma (CCP) were used to generate the plasma and the plasma parameters were varied. The ppMMAs were investigated using atomic force microscopy (AFM) and a Fourier Transform Infrared (FT-IR) spectroscopy. Dielectric constants of the ppMMA thin films were investigated using a impedance analyzer (HP4192A, LF Impedance Analyzer). Current-Voltage (I-V) characteristics of the organic thin film transistors (OTFTs) were investigated using a source measurement unit (SMU: Keithley 2612). Proposed method can be applied to dry-process to fabricate OTFTs during overall fabricating steps.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.703-703
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• 2013

다이아몬드상 탄소 박막(Diamond-like carbon, DLC) 박막은 낮은 마찰 계수, 높은 내마모성, 화학적 안정성, 적외선 영역에서의 높은 투과율 등의 장점을 바탕으로 MEMS (Micro-Electro Mechanical System) 소자와 MMAs (Moving Mechanical Assemblies)의 고체윤활코팅, 마그네틱 미디어와 하드디스크의 슬라이딩 표면 등 다양한 분야에 코팅소재로써 응용되어왔다 [1,2]. 현재 전기철도용 집전판은 마찰이 적고 전도성을 지니는 카본 소재로 구성되어 있다. 그러나 그 마모 비율이 너무 심하여 이를 개선할 수 있는 방안으로 고경도 저마찰력을 지니는 DLC 박막을 코팅 소재로써 제안하고자 한다. 그러나 기존에 DLC 박막은 절연특성이 매우 우수하기 때문에 기존에 전도성을 지니는 카본 집전판에 적용하기에는 어려움이 따른다. 따라서 DLC 박막 내에 실리콘(Si) 또는 금속(Metal)을 첨가시키거나, 금속 중간층을 포함시켜 전기적으로 전도특성을 향상시키는 방안이 제시되고 있으며, 본 연구에서는 DLC 박막과 유사하게 우수한 경도특성을 지니고, 낮은 마찰계수등을 지니는 비정질 탄소박막을 연구하여 카본 집전판에 코팅하고자하며, 특히 비정질 탄소박막에 금속 Ti를 도핑하여 집전판과의 접착력과 전기적 전도 특성을 향상시키고자 한다. Ti가 도핑된 탄소박막(TiC) 박막은 비대칭 마그네트론 스퍼터링(unbalanced magnetron sputtering; UBMS) 시스템을 이용하여 제작하였으며, 스퍼터링 조건 중 기판에 인가되어지는 기판온도에 따라 변화되어지는 TiC 박막의 트라이볼로지(Tribology) 특성을 고찰하고자 하였다. 증착시 기판온도의 증가는 TiC 박막의 경도, 마찰계수 특성등 트라이볼로지 특성을 향상시켰으며, 전기적 전도 특성을 향상시켰다. 이러한 결과는 스퍼터링 방법에 의해 증착되어진 TiC 박막내에 존재하는 sp2 결합과 관계가 있음을 확인할 수 있으며, 트라이 볼로지 특성은 TiC 박막내에 sp2 탄소결합의 비율 증가와 관련되어졌다. 특히 sp2 탄소결합은 TiC 박막 증착시 증가된 기판온도와 밀접한 관계가 있으며 기판온도의 증가에 따라 나노결정 클러스터의 크기와 수의 변화와 밀접한 관계가 있음을 확인하였다. 결국 기판온도는 TiC 박막의 트라이볼로지 특성을 향상시켰으며, 전기적 특성 또한 향상시켜 전기철도 집전판에 응용을 위한 소재로 평가할 수 있다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.181-181
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• 2008

DLC (Diamond-like Carbon) 박막은 높은 내마모성과 낮은 마찰 계수, 화학적 안정성 및 적외선 영역에서의 높은 투과율과 낮은 광 반사도, 높은 전기저항과 낮은 유전율, 전계방출특성 등 여러 가지 장점을 가진 물질이다[1]. 최근에는 DLC 박막의 여러 장점들과 산과 염기 유기용매에 대한 화학적 안정성으로 인하여 인조관절에서 인공심장의 판막에 이르기까지 의공학 관련 부품소재로 응용되고 있으며 내구성과 안정성에 있어서 탁월한 성능을 보여주고 있다. 또한 DLC 박막의 높은 경도와 낮은 마찰 계수, 부드러운 박막 표면 (수nm의 RMS 거칠기)의 장점을 살려 마그네틱 미디어와 하드디스크의 슬라이딩 표면에 사용되어지고, MEMS (Micro-Electro Mechanical System) 소자와 MMAs (Moving Mechanical Assemblies)의 고체윤활코팅으로 활용하여 미세기계의 내구성과 성능 향상을 도모할 수 있다. 이와 같이 DLC 박막은 다양한 분야에 응용되고 있으며, 박막이 지닌 여러 가지 장점들로 인하여 더 많은 분야에 응용될 가능성을 지닌 물질이다. 그러나 수 ${\mu}m$이상의 두께에서 박막이 높은 잔류응력 (residual stress)을 가지고, 열에 취약하여 이의 개선에 관한 연구들이 진행되어 지고 있다 [2]. 따라서 사용되는 목적에 따라 용도에 맞는 양질의 DLC 박막을 합성하기 위해선 합성 장치의 개발과 다양한 실험을 통한 최적의 합성조건 도출 등의 노력이 요구된다. 또한 DLC 박막 합성시의 여러 가지 증착 방법에 따른 박막 물성에 대한 재현성 확보 및 박막 증착에 관한 명확한 메커니즘 규명이 아직까지는 불분명하여 이에 관한 연구가 시급하다. 따라서 본 연구에서는 MEMS 소자와 MMAs의 고체윤활코팅으로 사용가능한 DLC 박막을 RF PECVD (Plasma Enhanced Vapor Deposition) 방식으로 합성하고 후열처리 온도에 따른 DLC 박막의 마찰계수 변화를 박막에 훼손을 주지 않는 FFM (Friction Force Microscopy) 방식을 사용하여 분석하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4272-4278
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• 2014

One of the most effective ways of preventing skin aging is to protect the skin from UV radiation, which was identified as the primary cause of photoaging. Therefore, it is necessary to develop natural and environment-friendly materials to the human skin. This study examined the effects of MAAs extracted from Chlamydononas hedleyi on UV protection and anti-inflammation in human skin cells. The function of porphyra-334 in the skin, which was isolated and purified from MMAs mixture, was tested in terms of its UV protective ability and anti-inflammation. As a result, porphyra-334 played a role in protecting the skin from UV radiation and anti-inflammation through the suppression of COX-2 expression. These results suggest that porphyra-334 can be a useful material in cosmetic products because it can protect the skin from UV radiation and anti-inflammation.

• Physical Therapy Korea
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• v.5 no.1
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• pp.17-29
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• 1998

The purpose of this study was to identify the relationship between sitting and standing balance in acute stroke patients and gait outcome, and to determine appropriate test times. The subjects of this study were 20 hemiplegic patients who had been hospitalized in Sangji University Oriental Medical Hospital from August 26, 1997 through November 3, 1997. Twenty patients with cerebral infarcts had sitting and standing balance assessed on the 5th day and 10th day of stroke onset. Gait outcome was assessed 5 weeks later using the MMAS (Modified Motor Assessment Scale) score. The data were analyzed by the Spearman's Rho test and Wilcoxon signed rank test. The results were as follows: 1) Correlation coefficients between sitting balance on the 5th day and 10th day after their stroke and gait outcome 5 weeks after their stroke were $r_s$=0.89 and $r_s$=0.83, respectively. All of the sitting balance data significantly correlated with gait outcome (p<0.05). 2) Correlation coefficients between standing balance on the 5th day and 10th day after their stroke and gait outcome 5 weeks after their stroke were $r_s$=0.82 and $r_s$=0.87, respectively. All of the standing balance data significant1y correlated with gait outcome (p<0.05). 3) The difference between sitting balance scores on the 5th day and 10th day after stroke onset were statistically significant (p<0.05). But the difference between standing balance scores on the 5th day and 10th day after stroke onset were not statistically significant (p>0.05). In conclusion, sitting and standing balance tests on the 5th day and 10th day after their stroke appear to be predictive of gait outcome. Also, the result of this study can provide reference for appropriate test times as an assessment of sitting and standing balance in stroke patients.

• PNF and Movement
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• v.5 no.2
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• pp.47-54
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• 2007

Purpose : The purpose of this study were to determine the effect of a Elastic Theraband Exercise Based of PNF L/E pattern on the gait of the chronic Hemiplegic Patients. Methods : We selected the 20 chronic Hemiplegic Patients not given treatment now and divided them into two groups of both 10 Elastic Theraband group and 10 Self Exercise. The first group went through a Elastic Theraband Exercise Based of PNF L/E pattern 30 minutes a day, 5 times a week, for 6 weeks. Exercise used to blue elastic band which 2 patterns of PNF by 1) hip extension - abduction - internal rotation with knee extension. 2) hip flexion - adduction - external rotation with knee flexion. The latter group experienced Self Exercise, 30 minutes a day, 5 times a week, for 6 weeks. Firstly, we measured the absolute improvement of gait velocity(m/s), cadence(steps/min) among walking characters. Secondly, we measured the functional walking ability such as Functional Ambulatory Category(FAC, score out of 5), Modified Motor Assesment Scale(MMAS, score out of 6). Data analysis was performed with using SPSS 12.0 win program. The descriptive analysis was used to obtain average and standard deviation. The independent t-test and the paired t-test were used to compare both the groups about pre and post training test. Treatment effects were established by pre and post assessment. Subjects tolerated the training well without side-effects. Therefore, the results of this study were as follows; Results : 1. There was a more significant improvement of Gait velocity(0.12m/s) Elastic Theraband group(p<.05). 2. There was a more significant improvement of cadence(9.40steps/min) Elastic Theraband group(p<.05). Conclusion : As we can see from above, the findings suggest that Elastic Theraband may be more effective than the Self Exercise for improving some gait parameters such as Gait velocity and Cadency. This conclusion also suggest that Elstic Theraband is more effective for the improvement of gait of chronic Hemiplegic Patients.