• 한국염색가공학회지
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• 제34권2호
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• pp.117-126
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• 2022

In this study, thermoplastic composites were manufactured using ABS(acrylonitrile butadiene styrene), PC(polycarbonate), and POE(polyolefin elastomer), which are thermoplastic plastics. Twin screw extruder and injection molding were used to manufacture thermoplastic composites. When the ABS/PC/POE thermoplastic composite material was manufactured, the POE mass fraction was set to 1 to 5 wt.%, and the thermal and mechanical properties according to the POE mass fraction were analyzed. Based on the physical properties of ABS/PC/POE, a 3D model in the form of an e-bike frame was created. After setting the boundary conditions, when an external load is applied, geometry simulation was performed to predict product performance. The ABS/PC/POE thermoplastic composite material exhibited the best physical properties when the mass fraction of POE was 3 wt.%. In the simulation results for the physical properties of the 3D model in the form of an e-bike frame, the best physical properties were shown when the mass fraction of POE was 2 ~ 3 wt.%. As a result, the manufacturing conditions for ABS/PC/POE thermoplastic composite materials were set, and research was conducted to reduce product development costs and development time.

• 대한화상학회지
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• 제23권1호
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• pp.25-29
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• 2020

This paper presents our clinical experiences for reconstruction of the linear depressed postburn scar band by rhombus subcutaneous pedicle skin flap (RSPF). We report new RSPF, it's versatility, and effectiveness for correction of the mild to moderate linear depressed postburn scar band. To correct the postburn scar band, we have newly designed the Rhombus Subcutaneous Pedicle Skin Flap (RSPF), which is made as rhombus-shaped skin flap on the inside of scar band. After excision of burn scar band, the each vertex of RSPF flap is advanced into the skin defects at apex of extended skin incision, which is starting from the upper and lower portion of the removed burn scar band at a near right angle. This flap can add more extra skin to adjacent superior and inferior area of excised scar band. We have experienced 2 cases of RSPF for reconstruction of linear depressed postburn scar band deformities in lower extremity. After 3 weeks to 3 months postoperative follow ups, relatively satisfactory results were obtained in all cases. We had successfully reconstructed the linear depressed postburn scar postburn band of lower extremity using the rhombus subcutaneous pedicle skin flap. For the correction of mild to moderate sized linear depressed postburn scar band deformities in extremity, the RSPF is simple, and very effective without donor morbidity.

• 한국염색가공학회지
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• 제33권4호
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• pp.210-219
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• 2021

It was intended to conduct basic research to reduce development lead time and cost consumed in DTP process technology development. For the simulation of HTPE fabric, virtual engineering software was used to generate fiber model, yarn model, fabric model, and finite element model of HTPE fiber. The purpose of this study is to analyze the correlation and error rate between the stiffness numerical analysis results according to the direct DTP process parameters using reactive dyes in the generated finite element model and the stiffness measurements of the actual sample ac- cording to ASTM D1388. And, after dyeing the HTPE plain fabric according to the direct DTP process parameters, we want to analyze the dyeability of the HTPE fabric fabrics according to the direct DTP process parameters through the color fastness analysis. When looking at the results of the analysis of the finite element model, a higher value was shown when the distance between the nozzle and the fabric was 3mm than when the distance was 10mm. When the distance between the nozzle and the fabric was 10mm and 7mm, the reactive dye did not penetrate sufficiently, resulting in poor clarity when viewed with the naked eye.

• 한국지반공학회논문집
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• 제26권4호
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• pp.37-45
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• 2010

기후변화로 인해 물의 증발량이 많은 지역의 지반에서는 자연적인 소금의 고결화 현상이 발생한다. 이러한 소금의 고결화 분포는 모래지반에서 모세관력에 영향을 받는다. 이 연구의 목적은 콘 관입시험, 전기전도율 측정, 사진 이미지 촬영, 비파괴 이미지 분석 그리고 탄성파에 의한 프로세스 모니터링을 이용하여 소금의 고결화 현상에 대한 모세관력의 효과를 관찰하는 것이다. 실험은 입상재료를 모형화한 글라스비즈를 소금물에 포화시킨 후, 오븐에 넣어 시료를 건조시킴으로써 고결화를 발생시켰다. 실험결과, 고결된 소금의 농도는 시료입경이 작은 경우 최상부에서 높았고, 시료입경이 큰 경우 중간 또는 하부에서 높았다. 고결된 시료에서 높은 소금농도의 위치는 해석적 방법으로 산정된 모세관 높이와 유사하였다. 본 연구에서 수행한 5가지 실험은 모세관력이 소금이 고결된 흙과 같은 입상재료의 거동에 중요한 영향을 끼치는 것을 보여준다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2021년도 춘계학술대회
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• pp.67-67
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• 2021

The genus Glycyrrhiza (Licorice) has been used as an oriental herbal medicine for a long time in Asian countries. Wongam (WG), which is Glycyrrhiza new variety, have been developed to improve limitation of licorice including low productivity, environmental restriction and insufficient components by Korea Rural Development Administration. To using WG as a herbal medicine, it is important to reveal the adverse effects in health. In this study, we evaluated the genotoxicity test of WG extract through in vitro bacterial reverse mutation (AMES) assay, in vitro chromosomal aberration assay and in vivo mouse bone marrow micronucleus assay. When compared with the control, WG extract with or without the S9 mix showed no genotoxicity in the AMES assay up to 5000 ㎍/plate and in the chromosomal aberration assay up to 1100 ㎍/ml. In micronucleus assay, no significant increase in the number of micronucleated polychromatic erythrocytes or in the mean ratio of polychromatic to total erythrocytes up to 5000 mg/kg/day for 2 days. The present study demonstrated that WG extract is safe and reliable herbal medicine since no detectable genotoxic effects at least under the conditions of this study.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2022년도 추계학술대회
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• pp.44-44
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• 2022

본 연구는 산림 생물다양성 특정 지역인 풍혈지 25개소를 대상으로 기후변화에 취약한 북방계식물 등의 현지내·외 보전 대책 수립과 풍혈지의 산림유전자원보호지역 지정을 위한 기초자료로 활용하기 위하여 조사를 수행하였다. 조사는 풍혈의 바람이 나오는 핵심지역 10m 를 중심으로 동서남북으로 각각 50m 범위에서 실시하였고, 2016년 4월부터 2021년 11월까지 계절별로 각 1~2회씩 수행하였다. 한국의 25개소 풍혈지의 관속식물상은 125과 486속 947종 23아종 75변종 7품종 총 1,052분류군으로 확인되었다. 조사 면적은 최대 0.09km²로 우리나라 산림면적 62,860km²의 0.00014%에 불과하지만, 우리나라 관속식물의 4,724종 중에서 22.27%가 출현하였다. 이는 풍혈지역이 산림생물다양성의 가치가 매우 높은 지역임을 확인해 볼 수 있다. 특기할만한 식물은 멸종위기야생생물이 산작약, 으름난초 등 6분류군, 희귀식물과 적색목록은 월귤, 개병풍 등 67분류군, 한반도 특산식물과 고유종이 병꽃나무 등 58분류군, 식물구계학적 특정식물은 개느삼 등 총 317분류군이 조사되었다. 북방계식물은 토끼고사리 등 181분류군, 석회암지대 식물은 덕우기름나물 등 32분류군이 확인되었다. 외래식물은 개망초, 달맞이꽃 등 75분류군이 확인되었고, 귀화율 7.13%와 도시화율 12.12%로 산출되었다. 본 연구대상지인 풍혈지 25개소의 식물지리학적 특정식물은 월귤, 흰인가목, 꽃개회나무, 각시괴불나무, 산솜방망이 등으로 파악되었다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2021년도 춘계학술대회
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• pp.65-66
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• 2021

Glycyrrhiza species (Licorice) are one of the most commonly used medicinal plants in Asian countries such as China, India and Korea. It has been traditionally used to treat many disease including cough, cold, asthma, fatigue, gastritis and respiratory tract infections. Glycyrrhiza new variety, Wongam (WG), have been developed by Korea Rural Development Administration and revealed several pharmacological effects. However, limited data are available on the potential adverse effects of the WG. Here, we evaluated the general toxicity of the WG extract through single oral dose toxicity study in Sprague-Dawley rats. After single oral dose administration, there was no mortality up to 5000 mg/kg during experiment period. In addition, there was no clinical signs including body weight change, gross findings and necropsy findings up to 5000 mg/kg during experiment period. To conclude, the no-observed-adverse-effect level (NOAEL) of WG was higher than 5000 mg/kg and no target organs were identified in male and female Sprague-Dawley rats.

• 한국재료학회지
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• 제34권1호
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• pp.27-33
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• 2024

Al₂O₃ has excellent sintering properties and is important in semiconductor manufacturing processes that require high-temperature resistance and chemical inertness in a plasma environment. In this study, a comprehensive analysis of the chemical characteristics, physical properties, crystal structure, and dispersion stability of three commercially available Al₂O₃ powders was conducted. The aim was to provide a technological foundation for selecting and utilizing appropriate Al₂O₃ powders in practical applications. All powders exhibited α-Al₂O₃ as the main phase, with the presence of beta-phase Na₂O-11Al₂O₃ as the secondary phase. The highest Na⁺ ion leaching was observed in the aqueous slurry state due to the presence of the secondary phase. Although the average particle size difference among the three powders was not significant, distinct differences in particle size distribution were observed. ALG-1SH showed a broad particle size distribution, P162 exhibited a bimodal distribution, and AES-11 displayed a uniform unimodal distribution. High-concentration Al₂O₃ slurries showed differences in viscosity due to ion release when no dispersant was added, affecting the electrical double-layer thickness. Polycarboxylate was found to effectively enhance the dispersion stability of all three powders. In the dispersion stability analysis, ALG-1SH exhibited the slowest sedimentation tendency, as evidenced by the low TSI value, while P162 showed faster precipitation, influenced by the particle size distribution.

• 한국진공학회지
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• 제17권1호
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• pp.34-39
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• 2008

저온에서 성장된 AlN (LT-AlN)층이 삽입된 $Al_xGa_{1-x}N/LT$-AlN/GaN 이종접합 구조를 금속유기 화학기상 증착법 (metal-organic chemical vapor deposition)을 사용하여 사파이어 기판 위에 제작하였다. Rutherford backscattering spectroscopy 실험을 통하여 $Al_xGa_{1-x}N$층의 Al의 조성비 x가 55% 임을 확인하였고, X-선 역격자 공간 mapping을 통하여 층간 변형력을 조사하였다. LT-AlN층의 삽입 여하에 따른 $Al_{0.55}Ga_{0.45}N$ 층의 깨짐 현상을 광학현미경과 주사전자현미경을 통하여 조사하였는데, LT-AlN 층이 삽입된 시료의 경우에 깨짐 현상이 현저히 줄어든 $Al_{0.55}Ga_{0.45}N$ 층을 얻을 수 있었다. 뿐만 아니라 LT-AlN 층이 삽입된 $Al_{0.55}Ga_{0.45}N$/LT-AlN/GaN 이종접합 구조에 대하여 이차원 전자가스 (two-dimensional electron gas, 2DEG) 관련된 photoluminescence (PL) 신호를 관찰하였다. 이 시료에 대하여 온도 변화에 따른 PL 실험을 수행하여 100 K 근방까지 2DEG 관련된 PL 신호를 관찰하였다. 여기광 세기에 따른 PL 실험을 통하여 ~3.411 eV에서 나타난 2DEG PL 신호와 함께 ${\sim}3.437eV$에서도 PL 신호가 관측되었는데, 이는 AlGaN/LT-AlN/GaN 계면에 형성된 2DEG 버금띠와 Fermi 에너지 준위에서의 재결합 특성으로 각각 해석되었다.

• 전자공학회논문지 IE
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• 제45권1호
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• pp.31-37
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• 2008

본 논문에서는 2.3GHz 주파수대역의 휴대무선인터넷 하향 주파수 변환기를 설계 및 제작하였다. 수신기에서 발생할 수 있는 문제점의 최소화 목적으로 저잡음 증폭기(Low Noise Amplifier)를 부가하게 되었다. 또한, 2.3GHz 대역이 75MHz로 하향 과정에서 손실을 최소화하고, 변환 효율을 높이고, 안정적인 특성을 발휘할 수 있도록 우수한 주파수 특성을 가진 소자를 사용하였다. 휴대무선인터넷 중계기는 TDMA(Time Division Multiplexing Access)방식을 사용하기 때문에 RF 스위치가 사용되었다. 제작 사양인, 입력전압 +8V 에서 1.2A의 전류를 소비, 60dB의 이득과 2.5dB 이하의 잡음지수, 입출력 전압정재파비(Voltage Standing Wave Ratio) 1.5이하, 혼변조 왜곡(Inter Modulation Distortion) 60dB 이상을 만족하였다. 환경 조건($-20^{\circ}C{\sim}70^{\circ}C$)에서 장시간의 신뢰성 시험을 통과하여, 제작된 휴대무선인터넷 RF 하향 변환기는 휴대무선인터넷 중계기에 적용 가능하다.