• Environmental Engineering Research
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• 제19권4호
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• pp.363-367
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• 2014

One chambered sediment microbial fuel cell (SMFC) was equipped with Fe, brass (Cu/Zn), Fe/Zn, Cu, Cu/carbon cloth and graphite felt anode. Graphite felt was used as common cathode. The SMFC was membrane-less and mediator-less as well. Order of anodic performance on the basis of power density was Fe/Zn ($6.90Wm^{-2}$) > Fe ($6.03Wm^{-2}$) > Cu/carbon cloth ($2.13Wm^{-2}$) > Cu ($1.13Wm^{-2}$) > brass ($Cu/Zn=0.24Wm^{-2}$) > graphite felt ($0.10Wm^{-2}$). Fe/Zn composite anode have twisted 6.73% more power than Fe alone, Cu/carbon cloth boosted power production by 65%, and brass (Cu/Zn) produced 65% less power than Cu alone. Graphite felt have shown the lowest electricity generation because of its poor galvanic potential. The estuarine sediment served as supplier of oxidants or electron producing microbial flora, which evoked electrons via a complicated direct microbial electron transfer mechanism or making biofilm, respectively. Oxidation reduction was kept to be stationary over time except at the very initial period (mostly for sediment positioning) at anodes. Based on these findings, cost effective and efficient anodic material can be suggested for better SMFC configurations and stimulate towards practical value and application.

• 한국콘텐츠학회논문지
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• 제8권1호
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• pp.86-92
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• 2008

디지털과 인터넷의 발전으로 시장이 공급자에서 소비자 중심으로 바뀌고 있다 기업들은 이러한 환경에 대응하기 위해 고객가치를 정확히 파악하고 제공하는 것이 중요하다. 고객가치는 성과 증대에 많은 영향을 미치기 때문에, 많은 기업들이 고객가치를 창출하기 위해 다양한 마케팅활동을 펼치고 있다. 고객가치를 창출하기 위해서는 무엇보다 고객 니즈와 시장 환경 변화를 지속적으로 모니터링 해야 한다. 따라서 본 연구는 고객모니터링 활동을 통해 변화하고 있는 고객가치요소를 파악하고 제공하여 어떻게 서비스 개선에 기여하는지를 분석하고자 한다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.286-289
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• 2004

This paper presents the fatigue characteristics of LIPCA (LIghtweight Piezo-Composite Actuator) device system. The LIPCA device system is composed of a piezoelectric ceramic layer and fiber reinforced lightweight composite layers. Typically a PZT ceramic layer is sandwiched by a top fiber layer with low CTE (coefficient of thermal expansion) and base layers with high CTE. The advantages of the LIPCA design are weight reduction by using the lightweight fiber reinforced plastic layers without compromising the generation of high force and large displacement and design flexibility by selecting the fiber direction and the size of prepreg layers. To predict the degradation of actuation performance of LIPCA due to fatigue, the cyclic electric loading tests using PZT specimens were performed and the strain for a given excitation voltage was measured during the test. The results from the PZT fatigue test were implemented into CLPT (Classical Laminated Plate Theory) model to predict the degradation of LIPCA's actuation displacement. The fatigue characteristic of PZT was measured using a test system composed of a supporting jig, a high voltage power supplier, data acquisition board, PC, and evaluated.

• 상하수도학회지
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• 제29권6호
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• pp.667-683
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• 2015

Since aged water treatment facilities could threaten the sustainable water supply, asset management system has been adopted for their systematic management. Level of Service(LoS) is one of critical components of asset management and could be quantified through benchmark index(BMI). Water supplier could estimate consumer's satisfaction and their performance through BMI to improve the LoS. We developed BMI for water treatment facilities from customer's satisfaction survey. BMI, represented with the Total Service Score(TSS), was assessed with water quality, water pressure, taste and odor, water rate, and service quality with weighing factors. BMI could, further, be used to assist the analysis of the life cycle cost to increase the unit of LoS.

• 정보학연구
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• 제6권4호
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• pp.93-111
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• 2003

웹기반 기업정보시스템은 다양한 애플리케이션, 콘텐츠 그리고 자료유형이 혼재되어 있어 시스템사용자의 정보처리효율과 정보해독성의 저해요인이 된다. 이러한 환경에서 보다 사용자친근성과 접근의 편의성을 제공할 수 있는 기술이 포털이며 이를 통하여 기업의 모든 정보시스템 그리고 외부시스템간의 원활한 연결을 도모할 수 있을 것이다. 본고에서는 기업포털(EP)을 정보처리포털(IPP), 의사결정지원포털(DPP) 그리고 지식경영포털(EKP)로 분류하고 이를 통하여 효율적인 시스템환경을 위한 구축방법을 제시하였다. 또한 구축에 따른 기술적인 문제보다는 개념적이고 절차적인 문제에 역점을 두고 분석하였다.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.740-754
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• 2015

This paper focuses on the reverse blocking busbar protection scheme with aim to improve the speed of its operation and at the same time to increase operational reliability, flexibility and stability of the protection during external and internal faults by implementation of the extended functionality provided by the IEC61850 standard-based protective Intelligent Electronic Devices (IEDs). The practical implementation of the scheme by the use of IEC 61850 standard communication protocol is investigated. The proposed scheme is designed for a radial type of a distribution network and is modeled and simulated in the DigSILENT software environment for various faults on the busbar and its outgoing feeders. A laboratory test bench is built using three ABB IEDs 670 series that are compliant with the IEC 61850 standard, CMC 356 Omicron test injection device, PC, MOXA switch, and a DC power supplier. Two types of the reverse blocking signals between the IEDs in the test bench are considered: hard wired and Ethernet communication by using IEC 61850 standard GOOSE messages. Comparative experimental study of the operational trip response speeds of the two implementations for various traffic conditions of the communication network shows that the performance of the protection scheme for the case of Ethernet IEC 61850 standard-based communication is better.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.137-143
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• 2013

This paper presents development of variable speed generation (VSG) system with energy saving function. The rubber tyred gantry crane (RTGC) requires the power from diesel-engine. Significant fuel savings by reducing the engine speed can be achieved, because all of operation modes except hoisting are required lower power than rated value of engine. When low speed operation output voltage of generator is decrease until acceptable range of motor driver inverters and auxiliary load supplier. According to power demand engine speed is varying from 20 to 60Hz, and voltage is varying between 210Vac and 480Vac. When idle mode or low power operation dc/dc converter operates by constant output voltage control and inverters dc site voltage is compensated by it. This paper proposed 3-phase interleaved boost converter which has the same structure as the commercially available 3-phase inverter and current sharing capability. 400kW interleaved converter is designed and a performance of converter is evaluated through several experiments with a RTGC system. Energy saving VSG system can cut down fuel consumption by 36% and 21.3% at idle and unidirectional load operations.

• 한국IT서비스학회지
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• 제9권1호
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• pp.91-111
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• 2010

An efficient industry structure is essential for competitive IT Service industry in a global world. The purpose of this research is to derive a policy direction paradigm for strengthening IT service industry structure. To find an effective policy direction, an in-depth analysis on deep-rooted problems of IT service industry has been conducted. The root-causes of industry problems are found with new perspectives on IT service industry. Past and present policies on IT service industry have been reviewed based on desirable industry behavior. A new policy paradigm and a roadmap for efficient industry policy are suggested. To justify adequacy of new policy direction, global benchmarking has been performed. USA, Germany, and Japan's IT service industry has been reviewed based on global competitiveness and desirable eco-system. And an in-depth analysis has been performed for two big competitors, India and China, The adequacy of the new policy paradigm has been tested, and mostly approved. IT service industry policy needs to be transformed from manufacturing concepts to service concepts, from domestic focus to global focus, from zero-sum policy to positive-sum policy, from supplier focus to market focus, from internal industry itself to co-growth with main industries. etc. The results of this study can be used for policy adjusting and policy making to strengthen IT service industry's global competitiveness and to improve long-term performance of Korean economy. Further in-depth researches with quantitative analysis will be needed to fully justify the adequacy of the derived new policy directions.

• The Journal of Asian Finance, Economics and Business
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• 제7권7호
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• pp.35-47
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• 2020

An economic downturn can occurred through unexpected events in various fields, such as the subprime mortgage crisis and the outbreak of Coronavirus Disease-2019 (COVID-19). Trade credit is important for small- and medium-sized enterprises (SMEs), especially during a monetary contraction, as it is the last option for firms that lack bank credit. This study aims to determine whether trade credit is profitable for the buyer and supplier firms during and after a financial crisis. We use panel data consisting of all trade credit transactions and financial statements of 5,751 Korean firms during the period 2008-2012. It shows that trade credit is more profitable for both buyers and suppliers in the post-crisis period than during the crisis. Moreover, trade payable is more effective for unconstrained buyers than for constrained buyers. Finally, a mixed strategy is superior to an aggressive or passive strategy of SMEs. The results suggest less profitability of trade credit during a period of contraction and greater sensitivity of the buyer SMEs, emphasizing the idiosyncratic liquidity strategy of each firm. This study can be helpful to develop a strategy of profitable trade credit for SMEs and to establish a policy of managing liquidity for the authority.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.906-917
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• 1996

This study was conducted to find possible application areas of the by-products generated from the incineration of rice husk. To this end, a pilot-scale rice husk incinerator system was constructed and its performed test was carried. Major findings are summarized as follows. 1. The rice husk incinerator system developed in this study performed satisfactory in terms of thermal efficiencies. At the optimum operating conditions, thermal conversion efficiency and heat exchanger efficiency was 97% ad 60%, respectively, while overall thermal efficiency of the system was 58%. Under all conditions tested, temperatures in the combustion chamber were quite uniform and crystallization of SiO$_2$ in the ash was negligible. 2. NOx and SOx content in the flue gas was well below the legal limit but the CO concentration was around the legal limit. 3. Thermal energy from combustion was successfully recovered by a heat exchanger to provide hot water, ash was found a good supplementary cementing m terial, and the flue gas also was an acceptable $CO_2$ supplier to greenhouses.