• 무역학회지
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• 제47권3호
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• pp.157-175
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• 2022

This study calculates agglomeration indices of manufacturing specialization and diversification in different regions of South Korea. Two types of agglomeration indices are introduced into the spatial durbin model (SDM) to analyzes the effects of manufacturing agglomeration in Korea on CO₂ emission intensity. The subjects of this study are 17 regions of South Korea , and the research period is from 2013 to 2019. This study also uses partial differential to analyze the direct and spillover effect of specialization and diversification agglomeration on CO₂ emission intensity. From the perspective of direct effect, the results reveal that specialization agglomeration is an important factor contributing to Korea's CO₂ emissions. However, diversification agglomeration has an obvious CO₂ emission reduction effect. From the perspective of spillover effect, this study finds that specialization agglomeration in one region can also contribute to CO₂ emissions in nearby regions. However, the development of diversification agglomeration in one region can have CO₂ emission reduction spillover effect on neighboring regions.

• 한국가스학회지
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• 제19권4호
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• pp.22-28
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• 2015

LPG가 수송용 연료로서 경쟁력을 유지하기 위해서는 지속적인 기술개발을 통해 휘발유와의 연비격차를 감소시키고 후처리시스템 등에 의한 가격 부담을 낮추어야 한다. 이에 본 연구에서는 안정적인 희박연소 구현을 통한 연비개선을 얻기 위해 실린더 중앙에 점화플러그와 연료분사기가 인접해 있고, 연료가 분사된 후 바로 점화가 이루어지도록 하는 분무유도방식의 LPG 직접분사엔진을 개발의 일환으로 연소제어인자의 변화에 따른 연소 특성을 분석하였다. 안정적인 연소를 위해 국부적으로 농후한 혼합기를 형성하는 성층희박연소의 특성상 일정 수준이상의 질소산화물이 배출되는 문제점을 갖고 있다. 질소산화물 저감을 위해 EGR을 적용한 결과 연료소비율과 THC의 배출은 약간 증가하지만 $NO_x$배출은 약 15% 저감되었다. EGR 적용에 의한 연소속도의 감소는 초기 화염발달 시기에 집중되어 나타났으며 흡입공기의 희석효과에 의해 EGR율이 증가할수록 최대 열방출율 및 열방출율 증가 기울기가 감소하였다.

• 분석과학
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• 제19권1호
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• pp.50-57
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• 2006

계면활성제를 완충용액에 섞어서 사용하는 미셀 모세관 전기영동법(micellar electrokinetic capillary chromatography, MECC)을 이용하여, 아조염료의 합성성분이면서 동시에 아조염료가 분해될 때 생성되는 H-acid modifier 혹은 2-naphthylamine-1,5-disulfonic acid 등의 디아조 성분에 대한 분석을 수행하고, 이 분리 결과를 Ion-Paring 메카니즘을 이용한 고성능 액체 크로마토그래피법과 비교하였다. 이 방법을 이용하여 Direct Blue 2, Direct Blue 6, Direct Blue 15 등의 직접염료 그리고 Reactive Orange 4와 같은 반응성 염료의 혼합용액을 완전히 분리할 수 있었다. 특히 각 염료의 환원용액을 H-acid, J-acid, ${\gamma}$-acid, orthanilic acid, sulfanilic acid 2-naphthylamine-1,5-disulfonic acid 등의 표준물질과 비교 분석한 결과, 사용한 각 염료의 디아조 성분인 H-acid modifier 혹은 2-naphthylamine-1,5-disulfonic acid에 대한 정보를 얻을 수 있었다. 본 연구의 결과를 토대로 Ion-Pair 크로마토그래피법과 모세관 전기영동법은 미지의 염료에 대한 성분확인 및 디아조 혹은 커플링 성분분석에 응용할 수 있음을 알 수 있었다.

• 대한화학회지
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• 제30권5호
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• pp.433-440
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• 1986

反陽性子性 溶媒인 dimethylsulfoxide中에서 p-nitrobenzeneazoresororcinol<4n-BAR>에 대하여 직류 폴라로그래피적 거동을 조사하였다. 0.05M $NaClO_4$의 DMSO溶媒中에서 4n-BAR은 1電子 2段階의 還元過程을 거쳐 hydrazo기를 포함하는 化合物로 還元된다. 還元反應의 中間 生成物은 比較的 反陽性子性 溶媒 속에서 安定하였다. 各 段階의 還元電流는 擴散支配的이었으며 一部 反應電流도 包含되었다. 酸을 添加함에 따라서 2個의 還元波가 하나로 合致되며 [acid]/[reductant]의 몰 (M)비가 M = 2인 條件에서 加電位(-E)에 대해 $log(i_d-i)(Mi_d/2-i)/i$/의 可逆性은 1電子 2段階 還元反應이고 非可逆的이었다.

• 분석과학
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• 제18권1호
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• pp.89-95
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• 2005

Studies on the electrochemical reduction of 7-acetoxy-4-bromomethyl-coumarin (ABMC), 7-acetoxymethyl coumarin (AMC), and coumarin in 0.1 M tetraethyl ammonium perchlorate acetonitrile solution were carried out with direct current, differential pulse polarography, cyclic voltammetry, and controlled potential coulometry. The electrochemical reduction of ABMC was proceeded through three irreversible steps coupled with the chemical reactions. The solution color was changed to yellow when the carbonyl group was reduced during second step and the color change was independent with bromo group of ABMC. Fluorescent intensity was highest when the electrochemical reduction was controlled at near the overpotential of supporting electrolyte (-2.3 volts).

• 대한족부족관절학회지
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• 제13권1호
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• pp.91-94
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• 2009

Metatarsal head and neck fractures are injuries that often result from a direct blow of a heavy objects to the metatarsal head. The head is often impacted or displaced to the plantar aspect that if not treated may cause malunion which later induces painful plantar calluses. If the fracture fragment is large enough, closed reduction may be successfully performed, but when the fragment is small or closed reduction is unsuccessful, open reduction is needed. We present our reduction and fixation technique for the metatarsal head and neck fractures using antegrade intramedullary Kirschner wire (K-wire) without opening the fracture site or infringing the metatarsophalangeal (MTP) joint which allows immediate motion of the joint and partial weight bearing in a stiff soled shoe.

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.308-310
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• 2022

Ultrawide bandgap gallium oxide (Ga₂O₃) semiconductors are known to have excellent photocatalytic properties due to their high redox potential. In this study, CO₂ reduction is demonstrated using nanostructured Ga₂O₃ photocatalyst under ultraviolet (254 nm) light source conditions. After the CO₂ reduction, C₂H₄ remained as a by-product in this work. Nanostructured Ga₂O₃ photocatalyst also showed an excellent endurance characteristic. Photogenerated electron-hole pairs boosted the CO₂ reduction to C₂H₄ via nanostructured Ga₂O₃ photocatalyst, which is attributed to the ultrawide and almost direct bandgap characteristics of the gallium oxide semiconductor. The findings in this work could expedite the realization of CO₂ reduction and a simultaneous C₂H₄ production using a low cost and high performance photocatalyst.

• 한국작물학회지
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• 제45권4호
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• pp.232-236
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• 2000

To obtain a basic information on the development of effective control strategies for weedy rice in direct seeding rice cultivation, occurrence patterns of weedy rice as influenced by different cultural practices such as cultivation method, water management, seeding time, and tillage were investigated in field or pot experiments. High occurrence of weedy rice was observed in a continuous direct seeding paddy field as compared to machine transplanted one. Based on the percent of weedy rice panicle over three years trial, high ridged dry seeding was highest with 36.9%, followed by wet seeding with 30.9%, water seeding with 14.6% and machine transplanting rice with 0.8%, indicating 97.8% reduction in weedy rice occurrence by machine transplanting rice as compared with high ridged dry seeding. Germination of weedy rice was promoted to 83-94 % when rice panicle was flooded from September 30 to October 10 for 6 days and 74-88% for 9 days on October 20. Weedy rice occurrence was also substantially reduced by delayed seeding on June 10 and intensive tillage. The results suggest that machine transplanting rice be more effective cultural practice than flooding treatment, delayed seeding and intensive tillage when weedy rice problem occurs in direct seeded paddy field.

• 전력전자학회논문지
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• 제7권3호
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• pp.297-302
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• 2002

유도전동기의 직접 토크 제어방식은 구조가 간단하여 구현이 용이하고, 빠른 토크 응답성을 갖는 것을 특징으로 견인용 유도전동기의 추동시스템 등에 그 응용분야를 넓혀가고 있다. 그러나 히스테리시스 제어기를 사용하여 출력전압을 결정하는 기존의 직접 토크 제어방식에서는 인버터의 스위칭 주파수가 히스테리시스 밴드 폭과 운전조건에 따라 가변하고 토크맥동이 발생하는 문제점이 있다. 따라서 본 논문에서는 인버터의 스위칭 주파수를 일정하게 유지하고 저속 및 고속 운전영역에서 전동기의 토크 및 고정자 전류 맥등을 저감하기 위한 목적으로 고정자 자속 제어개념과 공간전압벡터 P%에 의한 새로운 직접 토크 제어방식을 제안하였다. 시뮬레이션과 실험을 통해 제안한 알고리즘의 타당성을 입증하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권7호
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• pp.1061-1067
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• 2008

Direct Torque Control[DTC] and Vector Control are the two schemes developed for high performance induction motor drives. DTC based induction motors are being increasingly used in various industrial applications. DTC offers fast torque response and better speed control with lesser hardware and processing costs as compared to vector controlled drives. However, conventional DTC suffers from high torque ripple, current harmonics and low performance during torque transients. In this paper a new Direct Torque Control[DTC] method of induction motor is presented. In comparison with the conventional DTC method, the PWM technique is applied to proposed control method. In this method, decoupling mechanism is not required and the torque, the flux magnitude are under control using PI controllers and generating the voltage command for inverter control. Therefore torque and speed ripple could be reduced in comparison with the conventional switching table DTC.