• Journal of Biosystems Engineering
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• 제39권4호
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• pp.304-309
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• 2014

Purpose: Weeds cause significant losses in agricultural production. In this study, we investigated the effect of microwaves on the germination rates of cress and arugula seeds to determine whether microwaves could be developed as an effective alternative to conventional chemical-based herbicides. Methods: Seeds were planted at equal depths (8-10 mm) in a soil-turf mixture, and seeds were exposed to microwaves for 126 s, 70 s, and 50 s in a device constructed specifically for this study. A microwave tunnel was built using a variable speed conveyor belt and 4 magnetrons with a combined output power of 2.8 kW. Seeds that were not exposed to microwaves were germinated with regulated irrigation, temperature, and humidity controls in parallel with the treated seeds, and the germination rates were compared among the treatment groups. Results: We found that the exposure of cress and arugula seeds to microwaves for 126 s inhibited germination close to 100%. Cress seeds treated with microwaves for 50 s showed 95% germination compared to 65% germination of the untreated cress seeds. Conclusions: We predict that the thermal effect of microwave energy affects the germination ratio and germination rate of seeds.

• 한국정보통신학회논문지
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• 제6권2호
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• pp.330-338
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• 2002

소어휘 단어단위의 음성을 인식할 수 있는 음성인식 칩을 설계하였다. 설계된 칩은 음성 신호의 시작과 끝점 검출 부분, LPC 켑스트럼 계수 추출 부분, DTW 실행 부분과 외부 메모리 인터페이스 부분으로 구성되어있다. CMOS 0.35um TLM 공정으로 설계된 이 칩은 4x4mm2의 면적에 126,938개의 게이트로 만들어져 있다. 그리고 전용 H/W의 동작 속도는 5MHz에서 60MHz까지 조정 가능하다. 5MHz 클록을 사용하는 경우, 50∼60 프레임 정도의 소어휘 단어 단위의 음성을 초당 100,000개까지 비교할 수 있는 능력이 있고, 60MHz의 클록을 사용하는 경우는 초당 1,200,000개의 단어를 비교할 수 있다.

• Journal of Magnetics
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• 제11권3호
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• pp.126-129
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• 2006

The phosphate coating on the $(Fe_{0.97}Cr_{0.03})_{76}(Si_{0.5}B_{0.5})_{22}C_2$ amorphous powders with an average size of 10 ${\mu}m$ in diameter has been carried out in aqueous 1.0-2.0 wt% $H_3PO_4$ solutions, and the consolidation behavior and magnetic properties of their compressed powder cores has been investigated. The phosphate coating could provide efficient electrical insulation between amorphous powders and improved consolidation ability at room temperature. Especially when the powders were treated in more concentrated phosphoric acid solution, enhanced phosphate covering and higher frequency/dc-bias stability were achieved. The powder cores phosphate-coated in 2.0 wt% $H_3PO_4$ solution exhibited constant permeability of 21 up to 10 MHz, 110 of the quality factor at 0.9 MHz, 610 mW/cm3 core loss at 100 kHz/0.1 T and 89 of percent permeability at 100 kHz.

• Elastomers and Composites
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• 제50권2호
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• pp.126-131
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• 2015

$C_{60}$ nanowhiskers were synthesized from $C_{60}$ by liquid-liquid interfacial precipitation (LLIP) using $C_{60}$-saturated toluene and isopropyl alcohol. The $WO_3$ nanoparticles were synthesized by adding $3.8{\times}10^{-4}$ mole amount of ammonium metatungstate hydrate ($H_{26}N_6O_{40}W_{12}{\cdot}H_2O$) to 500 ml of distilled water, and the resulting solution was heated on a hot plate for 4 h. The $C_{60}$ nanowhiskers/$WO_3$ nanocomposites were prepared with $C_{60}$ nanowhiskers and $WO_3$ nanoparticles in an electric furnace at $700^{\circ}C$ in an argon gas atmosphere for 2 h. The $C_{60}$ nanowhiskers/$WO_3$ nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. UV-vis spectroscopy was used to evaluate the performance of the $C_{60}$ nanowhiskers/$WO_3$ nanocomposites as a photocatalyst in the degradation of organic dyes, such as methylene blue (MB) and brilliant green (BG) under ultraviolet light (254 nm).

• 전력전자학회논문지
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• 제22권2호
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• pp.126-133
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• 2017

The conventional battery charger requires two separate voltage and current compensators to achieve constant current and constant-current-charging profile. This compensator configuration leads to an inevitable transient response during the mode change between the constant current and the constant voltage operation. Futhermore, a tedious and complicated design process is required to consider a widely changing battery voltage and the nonlinear electrical properties of Li-ion battery. This study proposes a single integrated voltage-current compensator of the LLC resonant converter for Li-ion battery charger applications to overcome the aforementioned drawbacks. The proposed compensator is designed to provide a smooth and reliable performance during the entire charging process while providing the reduced design efforts and seamless mode transient response. Several experimental results based on a 300 W prototype converter and its theoretical analysis are provided to verify the effectiveness of the proposed compensator.

• 공업화학
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• 제26권3호
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• pp.251-258
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• 2015

본 연구에서는 L-lactide를 이용하여 수평균분자량(Mn)과 중량평균분자량($M_w$)이 각각 12,000, 14,000 g/mol인 PLLA (Poly L-lactic acid) 수지를 합성하였으며, 이 PLLA를 이용하여 PLLA-Br 중간체를 합성하였다. PLLA-Br 중간체를 이용하여 수평균분자량($M_n$)과 중량평균분자량($M_w$)이 각각 84,000, 126,000 g/mol인 PLLA-block-PMMA (Poly L-lactic acid-block-Polymethyl methacrylate) 공중합체를 최종적으로 합성하였으며 PLLA-block-PMMA 공중합체의 유리전이온도($T_g$)는 $95.5^{\circ}C$, 열분해 개시온도는 $289^{\circ}C$이었다. PLA에 PLLA-block-PMMA를 9 phr 혼용하고 $95^{\circ}C$에서 3배 이축연신한 다음 $120^{\circ}C$에서 2 min 동안 저온열처리하여 두께가 $50{\pm}3{\mu}m$인 PLA 필름을 제조하였다. 550 nm 파장에서 측정한 PLA 필름의 빛투과율은 88.5%, 인장강도는 44.5 MPa이었으며 PLA 필름의 인장강도를 현 수준보다 개선하기 위해서는 이축연신후 $120^{\circ}C$의 온도조건에서 2 min보다 긴 저온열처리시간이 필요하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제18권4호
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• pp.126-137
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• 2014

목재 건조의 용이성 및 품질확보, 2차 보존처리를 위한 기초자료 확보를 위해 초고주파를 이용한 캐나다산 직수입 미송의 가열 건조 특성은 다음과 같다. 초고주파 조사 후 목재 내부 온도변화 곡선을 분석한 결과 원주목은 3kW 30분 및 120분 가열 할 경우, 판목은 4kW 3분 및 9분 가열 시 안정적인 열분포와 소비 열량, 표면 함수분포 확보가 가능한 것으로 나타났다. 특히 초고주파 가열에 따른 표면 함수분포는 매우 균일한 Leveling이 이루어진 것으로 나타났으며, 함수 감소율도 중량대비 30% 이상인 것으로 나타나 건조효율이 우수한 것으로 나타났다. 또한 소비 열량 분석 결과에 따라 2차 액상 보존처리를 위한 침지 시 대량의 보존처리제 침투가 가능할 것으로 사료되므로, 초고주파 가열 목재는 빠른 함수감소 및 건조 특성과 많은 열량의 소비가 가능하여 산업재로의 사용 및 2차 응용제품 개발에 우수한 특성이 있는 것으로 사료된다.

• 산업식품공학
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• 제14권2호
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• pp.118-126
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• 2010

The fibrous material fraction as a by-product from the commercial aloe vera gel processing was obtained and freeze dried. The physicochemical characteristics such as the proximate composition, crystalline/surface structures and several physical functionalities including the water holding capacity (WHC), swelling capacity (SW), oil holding capacity (OHC), emulsion/foam properties and viscosity properties of this powdered sample (100 mesh) were investigated and analyzed by comparison with commercial $\alpha$-cellulose as a reference sample. The total dietary fiber content of powdered sample was very high as much as 87.5%, and the insoluble dietary and soluble dietary fiber content ratios were 77.6 and 22.4%, respectively. The FT-IR spectrum of powdered sample showed a typical polysaccharide property and exhibited a x-ray diffraction pattern for cellulose III and IV like structure. SW (8.24${\pm}$0.15 mL/g), WHC(6.40${\pm}$0.19 g water/g solid) and OHC(10.32${\pm}$0.29 g oil/g solid) of freeze dried aloe cellulose were about 3.3, 1.4 and 2 times higher than those of commercial $\alpha$-cellulose, respectively. Aloe cellulose (~2%, w/v) alone had no foam capacity while improved the foam stability of protein solution (1% albumin+0.5% $CaCl_{2}$) by factor of 300%. Emulsion capacity of 2%(w/v) aloe cellulose was about 70% level of 0.5%(w/v) xanthan gum, but its emulsion stability was about 1.2 times higher than that of xanthan gum. Also, aloe cellulose containing CMC (carboxyl methyl cellulose) of 0.3%(w/v) showed a very good dispersity. Aloe cellulose dispersion of above 1%(w/v) exhibited higher pseudoplasticity and concentration dependence than those of $\alpha$-cellulose dispersion, indicating the viscosity properties for new potential usage such as an excellent thickening agent.

• 한국전자통신학회논문지
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• 제14권1호
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• pp.119-126
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• 2019

본 논문에서는 WLAN 표준화에 적합하도록 삼중대역 안테나를 설계, 제작 및 측정하였다. 마이크로스트립 급전방법을 적용하여 세 개의 마이크로스트립 선로를 갖도록 설계하였으며 임피던스 특성을 향상시키기 위해 하나의 스터브 추가하여 삼중대역 특성을 얻었다. 요구되는 주파수 대역과 임피던스 대역폭을 얻기 위해 세개 분기 선로의 길이와 폭을 설정하고 스터브 길이를 조정하고 최적화하였다. 제안된 안테나는 $24.0mm(W){\times}60.0mm(L){\times}1.0mm(t)$의 유전체 기판 위에 $23.0mm(W_2+W_4){\times}53.1mm(L_1)$의 크기로 제작되었다. 제작 및 측정 결과로부터 900 MHz에서는 159 MHz (841~1000 MHz), 2400 MHz 대역에서는 630 MHz (2.32~2.95 GHz) 그리고 5000 MHz 대역에서는 1,040 MHz (4.95~5.99 GHz)의 대역폭을 얻었다. 또한 무반사실의 측정결과로부터 제작된 안테나의 이득과 방사패턴 특성을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제16권1호
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• pp.126-135
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• 2006

In a previous study, a biological response modifier (BRM) specifically enhancing the function of B-cells was isolated from Korean fermented soybean paste (Kfsp), but not from non-fermented soybeans. In this study, we attempted to isolate the bacteria producing the BRM from Kfsp (KfspBRM) by ELISA using anti-KfspBRM and by B-cell proliferation. Five bacteria whose culture supernatants showed the BRM activities were isolated, and one of them was identified as Bacillus licheniformis E1. The bacterial BRM (bBRM) originated from a slime layer of B. licheniformis El had a molecular weight of 1,594 kDa, and contained $33\%\;(w/w)$ of reduced sugar and $4.6\%\;(w/w)$ of protein content. The bBRM appeared to be a glycoprotein that is physically, structurally, and functionally similar to the KfspBRM, suggesting that the isolates including B. licheniformis El may produce the KfspBRM in the fermentation process of soybean paste. The mass production of the BRM by the bacterium may help to study B-cells in immunology, and the enrichment of the BRM in Kfsp may help patients in future who are medically in need of potentiation of B-cell proliferation and antibody production.