• 한국경제지리학회지
• /
• 제19권2호
• /
• pp.399-416
• /
• 2016

본 연구의 목적은 베트남 커피변경지역이 글로벌 가치사슬에 통합되는 과정에서 나타나는 가치의 전유 및 실현관계를 고찰하고, 공유가치창출에 대한 지속가능한 커피 글로벌 가치사슬의 의미를 분석하고자 한다. 최근 베트남의 대표적 커피 변경지역인 닥락성은 일반 커피생산의 착취적 가치사슬에서 인증 커피 생산에 따른 공유가치사슬로의 전환을 경험하였다. 이와 같은 전환은 글로벌 가치사슬에서 지역의 교섭력과 경쟁우위를 강화시킴으로써 지속적인 가치 창출을 수반할 수 있을 것으로 기대되었다. 그러나 실질적으로 농가, 중개인, 외국 가공업체와 같은 지역 이해관계자간 이윤 분배의 위계성이 더욱 심화되는 현상이 나타났다. 이와 같은 현상의 원인은 크게 두 가지 측면에서 나타났다. 첫째, 다국적기업, 중개인, 농가 간 전속관계의 형성은 이해관계자에게 안정적인 시장을 확보해 주었지만, 다국적 기업이 전속 커피 중개인을 통해 농가를 간접적으로 통제함으로써 이해관계자 간 위계가 더욱 심화되었다. 둘째, 공유가치창출의 명목으로 농가로 전가된 사회적 및 생태적 비용이 농가의 경제적 이윤 획득을 악화시킨 반면에 다국적기업으로의 비대칭적이고 위계적인 이윤 분배를 가져왔다. 그 결과, 닥락성에 보다 위계적이고 종속적인 글로벌 가치사슬이 형성되었다.

• 경영과학
• /
• 제34권3호
• /
• pp.1-14
• /
• 2017

This study empirically analyzes the impact of inventory management performance on the energy efficiency in Korean petrochemical companies. The concept of the distance function is used to define the energy efficiency and the estimation of the distance function is performed using the stochastic frontier analysis. The inventory turnover is selected as the variable indicating the inventory management performance of the company. The main results of this study are as follows. First, the inventory turnover has a positive impact on energy efficiency. Second, during the period over 2011~2015, while the gap in energy efficiency among the companies expanded, the average energy efficiency decreased. Third, the average energy efficiency in upstream process companies was greater than downstream process companies and the gap in energy efficiency among downstream process companies was greater than upstream process companies. Fourth, the average marginal effect of inventory turnover on energy efficiency increased gradually from 2011 to 2015. Finally, the average marginal effect of inventory turnover in downstream process companies was greater than upstream process companies, and the gap in the marginal effect of inventory turnover among downstream process companies was greater than upstream process companies. These results together imply the importance of inventory management in terms of energy efficiency.

• International Journal of Control, Automation, and Systems
• /
• 제3권3호
• /
• pp.461-468
• /
• 2005

This paper proposes a wheel-assembly automation system, which assembles a wheel into a hub of a vehicle hung to a moving hanger in a car manufacturing line. A macro-micro manipulator control strategy is introduced to increase the system bandwidth and tracking accuracy to ensure insertion tolerance. A camera is equipped at the newly designed wheel gripper, which is attached at the center of the end-effector of the macro-micro manipulator and is used to measure position error of the hub of the vehicle in real time. The redundancy problem in the macro-micro manipulator is solved without complicated calculation by assigning proper functions to each part so that the macro part tracks the velocity error while the micro part regulates the fine position error. Experimental results indicate that tracking error satisfies the insertion tolerance of assembly $({\pm}1mm)$, and thus it is verified that the proposed system can be applied to the wheel assembly task on a moving hanger in the manufacturing line.

• Advances in Energy Research
• /
• 제4권4호
• /
• pp.275-284
• /
• 2016

In the present work, ZnO nanoparticles (NPs) have been dispersed alone in the same solvent of the active layer for improving performance parameters of the organic solar cells. Different concentrations of the ZnO NPs have been blended inside active layer of the solar cell based on poly(3-hexylthiophene) (P3HT), which forms the hole-transport network, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which forms the electron-transport network. In the present investigations, the ZnO NPs may represent an efficient tool for improving light harvesting through light scattering inside active layer, electron mobility, and electron acceptance strength which tend to improve photocurrent and performance parameters of the investigated solar cell. The fill factor (FF) of the ZnO-doped solar cell increases nearly 14% compared to the non-doped solar cell when the doping is 50%. The present investigations show that ZnO NPs improve power conversion efficiency of the solar cell from 1.23% to 1.64% with increment around 25% that takes place after incorporation of 40% as a volume ratio of the ZnO NPs inside P3HT:PCBM active layer.

• Advanced Composite Materials
• /
• 제18권2호
• /
• pp.121-134
• /
• 2009

The present study investigated, both experimentally and numerically, the improvement of low-velocity impact damage resistance of carbon fiber reinforced plastic (CFRP) laminates due to through-the-thickness stitching. First, we conducted drop-weight impact tests for stitched and unstitched laminates. The results of damage inspection confirmed that stitching did improve the impact damage resistance, and revealed that the improvement effect became greater as the impact energy increased. Moreover, the stitching affected the through-the-thickness damage distribution. Next, we performed FEM analysis and calculated the energy release rate of the delamination crack using the virtual crack closure technique (VCCT). The numerical results revealed that the stitching affected the through-the-thickness damage distribution because the stitch threads had a marked effect on decreasing both the modes I and II energy release rate around the bottom of the laminate. Comparison of the results for models that contained delaminations of various sizes revealed that the energy release rate became lower as delamination size increased; therefore the stitching improved the impact resistance more effectively when the impact energy was higher.

• 대한기계학회논문집 C: 기술과 교육
• /
• 제5권1호
• /
• pp.69-77
• /
• 2017

나노기술은 IT, BT 기술과 함께 21세기에 기술혁명을 주도해 나갈 핵심 기술이기에 현재 우리나라를 비롯한 전 세계의 선진국들이 이 분야에 많은 연구 역량을 집중시키고 있고, 그 중에서도 나노소재 산업은 이 경쟁의 중심에 있다고 볼 수 있다. 본 연구에서는 기계공학 측면에서 나노소재 산업에 대하여 살펴보았다. 나노소재는 나노크기의 재료라는 점에서 기존의 마이크론 혹은 서브마이크론 재료에 서 발견할 수 없는 특별한 효과를 나타내거나 전혀 새로운 응용분야를 만들어낼 가능성이 크다. 특히 환경, 바이오, 에너지, 촉매 등 다양한 분야에서 그 응용이 기대된다.

• The Journal of Asian Finance, Economics and Business
• /
• 제8권4호
• /
• pp.849-855
• /
• 2021

The purpose of this study is to analyze and compare Islamic commercial banks and Islamic banking units with the stochastic frontier analysis (SFA) method during 2014-2018. The data in research using Islamic commercial banks and Islamic banking units. There are 10 Islamic commercial banks and 5 Islamic banking units that meet the criteria of purposive sampling. The calculation of efficiency level using the SFA method with the function of production shows that Islamic commercial banks and Islamic banking units always experience an increase in efficiency every year with the average level of efficiency of Islamic commercial banks being 0.43994, while the average rate of efficiency of Islamic banking units is slightly higher at 0.47654. This shows that Islamic banking units are slightly more optimal in generating total financing in the period 2010-2014. The test results using Independent Sample T-Test can be concluded that there is no difference in the efficiency value between Islamic commercial banks and Islamic banking units. Operating costs are not significant and have a positive effect on the total financing; total assets have a significant effect and a positive impact on total financing; labor costs are not significant and have a negative effect on total financing.

• 공업화학
• /
• 제29권3호
• /
• pp.318-324
• /
• 2018

본 연구에서는 물리적 활성화법인 수증기 활성화법을 이용하여 PAN (Polyacrylonitrile)계 활성탄소섬유를 제조하였다. 활성화는 온도와 시간을 변수로 하였으며, 활성화 온도(700, 750, $800^{\circ}C$)에 도달하였을 때 200 mL/min의 수증기 유량의 조건으로 PAN 탄소섬유의 활성화를 진행하였다. 제조된 활성탄소섬유의 기공구조를 분석하기 위하여 질소가스의 흡 탈 등온선을 통한 비표면적($S_{BET}$) 측정과 표면분석을 위한 AFM 분석을 실시하였다. 또한 인장시험을 실시하여 활성화 결과 형성된 기공구조가 섬유의 기계적 특성에 미치는 영향을 고찰하였다. 그 결과, 활성화 후 섬유의 비표면적($S_{BET}$)은 $448{\sim}902m^2/g$의 값을 나타냈으며, 인장강도는 58.16~84.92%, 탄성계수는 69.81~83.89%의 감소를 보였다.

• 비파괴검사학회지
• /
• 제20권1호
• /
• pp.27-32
• /
• 2000

본 논문에서는 고출력 펄스 Nd:YAG 레이저를 이용해서 원반형 시편의 한쪽 면에서 초음파를 발생시키고 반대 면에서 피드백 제어에 의해서 안정화된 마이켈슨 간섭계를 이용하여 열탄성 영역에서의 초음파를 검출하였다. 이론식에 의해서 계산된 열탄성 영역에서의 초음파 변위 파형이 실험에서 얻어진 파형과 유사한 것을 확인하였고, 특히 종파와 횡파의 음속이 접촉식 트랜스듀서를 이용하여 펄스-에코법으로 측정한 음속과 거의 일치하는 것을 확인하였다. 레이저 초음파를 이용한 응용예의 하나로 원반형 시편을 노 안에 넣고 음속을 계측한 결과 온도의 증가에 따라 음속이 감소하는 것을 확인하였다.

• 한국재료학회지
• /
• 제29권1호
• /
• pp.11-15
• /
• 2019

Severe wall thinning is found on the tube of a low-pressure evaporator(LPEVA) module that is used for a heat recovery steam generator(HRSG) of a district heating system. Since wall thinning can lead to sudden failure or accidents that lead to shutdown of the operation, it is very important to investigate the main mechanism of the wall thinning. In this study, corrosion analysis associated with a typical flow-accelerated corrosion(FAC) is performed using the corroded tube connected to an upper header of the LPEVA. To investigate factors triggering the FAC, the morphology, composition, and phase of the corroded product of the tube are examined using optical microscopy, scanning electron microscopy combined with energy dispersive spectroscopy, and x-ray diffraction. The results show that the thinnest part of the tube is in the region where gas directly contacts, revealing the typical orange peel type of morphology frequently found in the FAC. The discovery of oxide scales containing phosphate indicates that phosphate corrosion is the main mechanism that weakens the stability of the protective magnetite film and the FAC accelerates the corrosion by generating the orange peel type of morphology.