• Textile Coloration and Finishing
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• v.34 no.2
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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.

• Journal of the Korean Burn Society
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• v.23 no.1
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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.

• Textile Coloration and Finishing
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• v.33 no.4
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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.

• Journal of the Korean Geotechnical Society
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• v.26 no.4
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• pp.37-45
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• 2010

Salt cementation, a typical naturally-cemented phenomenon, may occur due to water evaporation under the change of climate. Capillary force may influence the distribution of cement in granular soils. This study addresses the effect of capillary force on salt cementation using five different techniques: cone penetration test, electrical conductivity measurement, photographic imaging technique, nondestructive imaging technique, and process monitoring by elastic wave. Glass beads modeling a particulate media was mixed with salt water and then dried in an oven to create the cementation condition. Experimental results show that salt cementation highly concentrates at the top of the small particle size specimens and at the middle or the bottom of the large particle specimens. The predicted capillary heights are similar to the locations of high salt concentration in the cemented specimens. Five suggested methods show that the behavior of salt-cemented granular media heavily depends on the capillary force.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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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.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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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.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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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.

• Korean Journal of Materials Research
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• v.34 no.1
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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.

• Journal of the Korean Vacuum Society
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• v.17 no.1
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• pp.34-39
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• 2008

We have investigated the characteristics of $Al_{0.55}Ga_{0.45}N$/GaN heterostructures with and without low-temperature (LT) AlN interlayer grown by metalorganic chemical vapor deposition. The structural and optical properties were systematically studied by Rutherford backscattering spectroscopy (RBS), X-ray diffraction (XRD), optical microscopy (OMS), scanning electron microscopy (SEM), and photoluminescence (PL). The Al content (x) of 55% and the structural properties of $Al_xGa_{1-x}N$/GaN heterostructures were investigated by using RBS and XRD, respectively. We carried out OMS and SEM experiments and obtained a decrease of the crack network in $Al_{0.55}Ga_{0.45}N$ layer with LT-AlN interlayer. A two-dimensional electron gas (2DEG)-related PL peak located at ${\sim}3.437eV$ was observed at 10 K for $Al_{0.55}Ga_{0.45}N$/GaN with LT-AlN interlayer. The 2DEG-related emission intensity gradually decreased with increasing temperature and disappeared at temperatures around 100 K. In addition, with increasing the excitation power above 3.0 mW, two 2DEG-related PL peaks were observed at ${\sim}3.411$ and ${\sim}3.437eV$. The observed lower-energy and higher-energy side 2DEG peaks were attributed to the transitions from the sub-band level and the Fermi energy level of 2DEG at the AlGaN/LT-AlN/GaN heterointerface, respectively.

• 전자공학회논문지 IE
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• v.45 no.1
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• pp.31-37
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• 2008

A Wibro RF down converter of 2.3GHz band is designed and implemented in this paper. The problems that can occur in the receiver LNA(Low Noise Amplifier) to minimize additional purposes. In addition, 2.3GHz band from the 75 MHz downward to minimize the losses in the process, transform and improve efficiency, and achieve stable characteristics can be used to make high frequency characteristics of the device. Wibro repeater uses a TDMA(Time Division Multiplexing Access) method is needed because the RF switch. Production criterion specification, the input voltage from +8 V 1.2A of current consumption, 60dB gain and the noise figure of less than 2.5dB, VSWR(Voltage Standing Wave Ratio) less than 1.5, more than IMD(Inter Modulation Distortion) 60dB satisfied. Environmental conditions ($-20^{\circ}C$ to $70^{\circ}C$) to pass the test of reliability in a long time, that seemed crafted Wibro down converter be applied to the Wibro repeater.