• Journal of Electrochemical Science and Technology
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• 제14권2호
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• pp.152-161
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• 2023

Vanadium redox flow batteries (VRFBs) have been considered one of promising power sources for large scale energy storage systems (ESS) because of their excellent cycle performance and good safety. However, VRFBs still have a few challenging issues, such as poor Coulombic efficiency due to vanadium crossover between catholyte and anolyte, although recent efforts have shown promise in electrochemical performance. Herein, the vanadium complexes with various glyme ligands have been examined as active materials to suppress vanadium crossover between catholyte and anolyte, thus improving the Coulombic efficiency of VRFBs. The conventional Nafion membrane has a channel size of ca. 10 Å, whereas vanadium cation species are small compared to the Nafion membrane channel. For this reason, vanadium cations can permeate through the Nafion membrane, resulting in significant vanadium crossover during cycling, although the Nafion membrane is a kind of ion-selective membrane. In this regard, various glyme additives, such as 1,2-dimethoxyethane (monoglyme), diethylene glycol dimethyl ether (diglyme), and tetraethylene glycol dimethyl ether (tetraglyme) have been examined as complexing agents for vanadium cations to increase the size of vanadium-ligand complexes in electrolytes. Since the size of vanadium-glyme complexes is proportional to the chain length of glymes, the vanadium permeability of the Nafion membrane decreases with increasing the chain length of glymes. As a result, the vanadium complexes with tetraglyme shows the excellent electrochemical performance of VRFBs, such as stable capacity retention (90.4% after 100 cycles) and high Coulombic efficiency (98.2% over 100 cycles).

• 한국전자거래학회지
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• 제18권1호
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• pp.13-31
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• 2013

본 논문은 최근 관심과 연구가 증가하고 있는 공급망 가시성을 더 잘 이해하기 위해 IOS 가시성과 공급망 성과에 대해, 그리고 IOS 가시성의 영향력에 대한 새로운 개념을 제안하였다. 그리고 이를 위해 기업간 협력에서 IOS의 핵심적 역할에 대해 고찰하였으며, 기업간 IOS 가시성의 선행요인과 결과요인을 살펴보았다. IOS 가시성의 결정인자를 자원종속이론(RDT)과 관계적 관점(RV)으로 구분하여 두 이론의 설명력 차이를 경험적으로 검증하였고, 공급망 협력을 구매자-공급자 관점 모두를 수용하여 종합적인 분석방법을 시도하였다. 또한 IOS 가시성을 측정하기 위한 도구를 개발하였고 그것을 실증적으로 확인하였다. 연구결과, IOS 가시성이 공급망 성과에 매우 중요한 결정요인이고, 공급망 참여자간 관계특성요인이 IOS 가시성의 유의미한 결정인자이며, 공급망 협력관계에서는 자원종속이론보다 관계적 관점이 설명력과 타당성이 더 우세함이 확인되었다.

• 시스템엔지니어링학술지
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• 제15권1호
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• pp.34-42
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• 2019

Receiving great attention of IoT and 4th industrial revolution, the necessity comes to the fore of the plant system which aims making it smart and effective. Smart Factory is the key realm of IoT to apply with the concept to optimize the entire process and it presents a new and flexible production paradigm based on the collected data from numerous sensors installed in a plant. Especially, the wireless sensor network technology is receiving attention as the key technology of Smart Factory, researches to interface those technology is actively in progress. In addition, IoT devices for plant industry security and high reliable network protocols are under development to cope with high-risk plant facilities. In the meanwhile, Blockchain can support high security and reliability because of the hash and hash algorithm in its core structure and transaction as well as the shared ledger among all nodes and immutability of data. With the reason, this research presents Blockchain as a method to preserve security and reliability of the wireless communication technology. In regard to that, it establishes some of key concepts of the possibility on the blockchain based IoT Edge devices for Plant O&M (Operations and Maintenance), and fulfills performance verification with test devices to present key indicator data such as transaction elapsed time and CPU consumption rate.

• 한국콘텐츠학회논문지
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• 제16권10호
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• pp.299-310
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• 2016

본 논문에서는 사물인터넷 환경에서 사용되는 저전력 통신 기술인 IEEE 802.15.4 MAC (Media Access Control) 프로토콜의 성능 분석을 수행한다. 사물인터넷 환경에서는 기기 종류가 다양하고 생성되는 트래픽 특성도 상이하기 때문에 기존 연구와는 달리 트래픽이 혼재되어 있는 heterogeneous traffic 환경을 고려한다. 마코프 체인을 통해 프로토콜의 성능을 MAC 파라미터의 함수로 도출하였고 이를 기반으로, 사용되고 있는 애플리케이션을 위한 에너지 효율적인 최적 MAC 파라미터를 실시간으로 찾는 프레임워크를 설계하였다. 제안 방식은 기존의 파라미터를 고정시켜 운용하는 방법 대비 에너지 이득이 있음을 애플리케이션 시나리오별 비교를 통해 보였고, 제안된 프레임워크가 연산 능력의 한계를 가지는 소형 기기에서도 충분히 사용될 수 있음을 정확도와 속도 측면에서 검증하였다.

• 한국통신학회논문지
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• 제39A권10호
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• pp.579-584
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• 2014

본 논문에서는 패치형 ESPAR(Electronically Steerable Parasitic Array Radiator) 안테나를 이용한 빔 공간 MIMO(beamsapce mulitple input multiple output) 시스템을 제안한다. 기존의 모노폴 ESPAR 안테나의 경우 단일 RF 체인을 갖기 때문에 하드웨어의 비용과 RF회로의 전력 소모를 절감할 수 있는 장점을 가진다. 하지만 공간적 제약이 큰 휴대용 이동기기에 적용하기 문제점이 있다. 따라서 부피를 간소화 시키는 방법으로써 패치형 ESPAR 안테나를 설계하고 단일 RF 체인으로 MIMO 기술이 가능한 빔 공간 MIMO 시스템에서의 성능을 분석한다. 본 논문에서 설계한 패치형 ESPAR 안테나를 통해 빔패턴이 ${\pm}15$도의 앙각의 변화를 가지는 것을 확인하였고, 또한 이 ESPAR 안테나를 사용하여 빔 공간 MIMO 시스템을 구현하고 이 시스템의 BER 성능을 확인하였다.

• International journal of advanced smart convergence
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• 제11권3호
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• pp.42-48
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• 2022

Currently, the world is facing severe inflation due to Corona and the war in Ukraine, and it is causing a lot of difficulties for us. Companies are facing a lot of restrictions on their economic activities compared to the past due to supply chain problems and foreign exchange rates. In this situation, many countries have been implementing various smart factory promotion projects to secure competitiveness through productivity improvement in the manufacturing industry. In this study, the contents of smart factory promotion in major countries were reviewed, and problems raised about the implementation of smart factory in Korea, which are being implemented based on this, were described. It is most reasonable to judge the success of a smart factory by the achievement of the performance indicators presented at the time of the project. Therefore, based on the performance index of the business, which is a key factor in determining the success or failure of a smart factory, we investigated whether the company's smart factory promotion can be carried out successfully through examples

• Asian-Australasian Journal of Animal Sciences
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• 제22권7호
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• pp.1060-1068
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• 2009

The buffalo (Bubalus bubalis) is an important contributor to milk, meat, power, fuel and leather production in many developing countries. Buffaloes can be categorized into Asian and Mediterranean buffaloes. Asian buffalo includes two subspecies known as Riverine and Swamp types. Riverine (water buffalo) and Swamp buffaloes possess different genetics (50 vs. 48 chromosomes, respectively), morphology (body frame, body weight, horn shape and skin color) and behavior (wallowing in mud or water) and thus, are reared and used for different purposes. Low per head milk yield, poor reproductive performance (seasonal breeding behavior, anestrous, and longer calving interval) and low growth rate in buffaloes have been attributed to insufficient supply of nutrients. In many parts of Asia, where the buffalo is an integral part of the food chain and rural economy, irregular and inadequate availability of quality feedstuffs and their utilization are hampering the performance of this unique animal. Balanced nutrition and better management can enhance buffalo productivity. Many efforts have been made in the last few decades to improve nutrient supply and utilization in buffaloes. Recent research on locally available feed resources such as crop residues, and industrial by-products, dietary addition of micronutrients, use of performance modifiers and use of ruminally protected fat and protein sources have shown significant potential to improve growth, milk yield and reproductive performance of buffaloes. However, a number of issues, including establishment of nutrient requirements for dairy and beef, development of buffalo calf feeding systems, nutritional management of metabolic and reproductive anomalies, and understanding and exploitation of the buffalo gut ecosystem, need to be addressed. Extensive coordinated research and extension efforts are required for improved buffalo nutrition in developing countries.

• 한국경영과학회지
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• 제26권4호
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• pp.133-141
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• 2001

Rapid development in computer and network technology these days has created in environment in which decisions for manufacturing companies can be made in a much broader perspective. Especially, better decisions on production and distribution planning(PDP) problems can be made laking advantage of real time information from all the parties concerned. However, since the PDP problem-a core part of the supply chain management- is known to be the so-called NP-hard problem, so heuristic methods are dominantly used to find out solutions in a reasonable time. As one of those heuristic techniques, many previous studios considered genetic a1gorithms. A standard genetic a1gorithm applies rules of reproduction, gene crossover, and mutation to the pseudo-organisms so the organisms can pass along beneficial and survival-enhancing trails to a new generation. When it comes to representing a chromosome on the problem, it is hard to guarantee an evolution of solutions through classic a1gorithm operations alone, for there exists a strong epitasis among genes. To resolve this problem, we propose a hybrid genetic a1gorithm based on Silver-Meal heuristic. Using IMS-TB(Intelligent Manufacturing System Test-bed) problem sets. the good performance of the proposed a1gorithm is demonstrated.

• 경영정보학연구
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• 제19권4호
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• pp.1-25
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• 2017

재무적 성과 측면의 높은 불확실성에도 불구하고, 기업들은 기술에 대한 투자를 지속적으로 확대하고 있다. 이는 기업들이 단기적 운영효율성의 증대는 물론 지속적 경쟁우위를 창출하고 유지하는 데 있어 기술투자를 중요하게 인식하고 있기 때문이다. 주목할 점은 개별 기업의 기술투자 전략과 그에 따른 세부적인 양상 혹은 패턴이 동일 산업 내에서도 상이한 모습을 보이고 있으며, 이러한 차이점이 궁극적인 기업성과의 차이로 이어지고 있다는 것이다. 본 연구는 이러한 기술투자를 전통적인 R&D 투자와 IT 투자로 구분하고, 두 가지 유형의 기술투자가 조합되어 만들어 내는 일종의 기술투자 패턴이 기업규모 및 공급사슬 상에서의 위치에 따라 기업성과에 어떤 영향을 미치고 있는 지에 대해 살펴보았다. 이를 위해 국내 562개 제조기업을 대상으로 수집된 데이터를 퍼지셋 질적비교분석(fsQCA: fuzzy-set Qualitative Comparative Analysis)을 통해 살펴보았다. 분석 결과, 상대적으로 기업규모가 큰 기업의 경우 세부적인 기술투자 패턴이 기업성과에 미치는 영향의 정도가 낮은 것으로 나타난 반면, 규모가 작은 기업의 경우 그 영향의 정도가 큰 것으로 나타났으며, 공급사슬 상에서의 위치에 따른 영향 역시 큰 것으로 나타났다. 이는, 기업규모가 작은 기업일수록 높은 기업성과를 얻기 위해서는 주어진 경영환경에 따라 보다 적합한 형태의 기술투자 전략이 요구된다는 것을 의미한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.67-70
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• 2003

In this paper the main topologies of one-bit full adders, including the most interesting of those recently proposed, are analyzed and compared for speed, power consumption, and power-delay product. The comparison has been performed on circuits, optimized transistor dimension to minimize power-delay product. The investigation has been carried out with properly defined simulation runs on a Cadence environment using a 0.25-${\mu}m$ process, also including the parasitics derived from layout. Performance has been also compared for different supply voltage values. Thus design guidelines have been derived to select the most suitable topology for the design features required. This paper also proposes a novel figure of merit to realistically compare n-bit adders implemented as a chain of one-bit full adders. The results differ from those previously published both for the more realistic simulations carried out and the more appropriate figure of merit used. They show that, except for short chains of blocks or for cases where minimum power consumption is desired, topologies with only pass transistors or transmission gates are not attractive.