• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.117-124
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• 2016

Solar photovoltaic pumping system is one of most important of renewable energy applications especially in rural areas. Besides, the control strategy for standalone solar pumping system based on induction motor and without DC/DC converter has been widely studied and discussed in the literature. This topology is of great concern due its economic issues, especially when a standard frequency converter (SFCs) with scalar control is used instead of a dedicated PV inverter. This paper proposes an external control module to generate SFCs frequency reference in order to ensure both maximum power point tracking (MPPT). We present method of modeling and control of photovoltaic pumping system based centrifugal pump controlled by new improved incremental conductance in order to optimize the price and operation of pumping system this MPPT algorithm have many advantages like can be eliminate proportional integral controller It is a low cost solution since it requires no additional power equipment. The induction motor driven pump that is powered by a solar array is controlled by the indirect field oriented control (IFOC). The effectiveness of the proposed approach is illustrated by simulations carried out under Matlab Software. The experimental results are compared with simulation results.

• 품질경영학회지
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• 제38권4호
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• pp.521-530
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• 2010

Global regulatory pressures relating climate change and environmental responsibility are asking companies to find out the best way for sustaining their continuous business growths. It could be known that inadequate management for environmental issues are bad for business, negatively affecting brand image, causing unnecessary losses and costs for environmental preservation. For this reason, environmentally conscious green business growth has been recognized as an essential requirement for a company to stay in business. Many companies are looking for green business opportunities of improving their environmental and financial results, and struggling with how green fits into their business. In this paper, the Green Six Sigma, an environmentally conscious Six Sigma methodology, is presented as a way to find solutions for green growths. The Six Sigma is known as a disciplined, data-driven approach and methodology for achieving world-class performance in any process from manufacturing to transactional. In chronological order, the Six Sigma has been evolved from Motorola's quality-oriented methodology to GE's cost-oriented lean approach, and is being evolved and developed as an environment-oriented green growth approach. There is no doubt that the Green Six Sigma, as an engine of green growth, is a power tool for achieving competitive business performance and reducing the impact on the environment.

• ETRI Journal
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• 제34권3호
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• pp.308-318
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• 2012

As mobile markets in most developed countries are rapidly coming close to saturation, it is increasingly challenging to cover the cost of providing the network, as revenues are not growing. This has driven mobile operators, thus far mostly involved in facility-based competition, to turn their attention to network sharing. There exist various types of mobile network sharing (MNS), from passive to active sharing. In this paper, we propose a model, based on the supply-demand model, for evaluating the economic effects of using six types of MNS. Our study measures the economic effects of employing these six types of MNS, using actual WiBro-related data. Considering lower service price and expenditure reduction, the total economic effect from a year's worth of MNS use is estimated to be between 513 million and 689 million USD, which is equal to three to four percent of the annual revenue of Korean mobile operators. The results of this study will be used to support the establishment of a MNS policy in Korea. In addition, the results can be used as a basic model for developing various network sharing models.

• 기술혁신연구
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• 제7권1호
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• pp.36-59
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• 1999

Fundamental advances in the biotechnologies are exerting a profound influence on the health care, agricultural, industrial chemical, environmental, and other industrial fields. Korean government are now more and more realizing the importance of biotechnology as a main technology for the 21st century. But any technical progress is largely the result of a complex set of relationships among the firms, institutions and others involved in development. So understanding the complexity is very important to make promoting strategies and it is even critical in the field of biotechnology. The reason is that commercialization of research results in biotechnology is strongly related with the national science bases provided by academic and public institutes. And its applicable industrial sectors are very diverse. So it is very important to make a effective collaboration system among many R&D related agents. This article discusses and compares both USA and Japanese framework of national innovation systems in the field of biotechnology. The American Innovation system encourages basic research in the biological sciences, and fosters the creation of small venture firms that focus on the development of novel products. America's peculiar incentive structure, derived from its research and educational system, financial system, and regulatory environment has driven USA labs and firms to the forefront of many biotechnology fields. The Japanese institutional environment in contrast, supported the strategy of building production expertise. Firms were urged to use the new techniques as a way of leapfrogging into a second generation of bio-products, in that cost and production advantages count. But the strategy was not effective as expected and Japanese firms have remained competent but not prominent rivals. The differing situations in USA and Japan with regard to biotechnology have many suggestions for our bioindustry. In the conclusion of this article, we translate USA and Japan's experiences to some suggestions which guide for promoting Korea's biotechnology R&D and commercialization activities.

• Spatial Information Research
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• 제1권1호
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• pp.39-53
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• 1993

지리 정보시스템(Geographical Information System)을 이용하여 도심지 Non Pount Source오염 물질의 양이 오염원 종류별로 확인되고 적절하한 오염감소를 위한 대책이 마련되었다. 경험에 의한 공해물질 예측모델을 운용하기 위한 모든 입력 자료들이 도심지의 거리 구획별(Street block)별로 제공되어 각 거리 구획별 오염량이 계산되었다. 계산된 오염량은 각 우수 배출구별로 합산되어 오염량이 많은 지역이 판명되었다. 또한 오염량을 줄이기 위하여 인공호수를 만들기 위한 적지분석이 수행되었으며, 그에 따른 비용분석이 이루어졌다. 본 연구는 지형정보시스템의 도심지 공해연구에의 기여도를 입증시켜 주었다.

• 한국산학기술학회논문지
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• 제20권8호
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• pp.634-641
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• 2019

세계 인구는 2019년 현재 77억 명에 달하고 있다. 이러한 추세에도 불구하고 모든 도시가 성장하고 있는 것은 아니다. 늘어나는 인구의 대부분은 편의시설, 일자리 문제로 큰 도시로 몰리고 있으며 이러한 현상은 중소도시의 인구감소를 유발하고, 더 나아가 특정도시에 있어서는 고용감소, 경기침체와 같은 결과로 이어지고 있다. 국내도 예외는 아니며 전국의 인구가 특별시, 광역시 등으로 몰리고 있는 추세이다. 일찍이 해외에서는 이러한 현상들을 해결하기 위해 오로지 도시의 성장에만 초점을 맞추는 전략이 아닌, 도시의 축소에 대응하는 방법을 연구하기 시작하였다. 본 논문에서는 국내 도시들의 인구동태를 파악하고 축소도시로 선정된 도시 사례를 파악하고 그 현황을 분석하였다. 다음으로 같은 맥락에서 해외 사례를 통해 축소도시의 문제에 대응하기 위한 전략으로 선택된 스마트 축소도시의 개념을 파악하였다. 이를 통해 국내와 해외의 대응 전략상의 차이점을 비교하였다. 결론에서는 일반적인 스마트 축소도시 전략에서 발생할 수 있는 문제점을 예측, 새로운 대안으로 유연한 스마트 축소도시(FSSC: Flexible Smart Shrinking City) 전략을 제안하여 자원과 비용을 효율적으로 사용하기 위한 방향을 제시하였다.

• 한국IT서비스학회지
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• 제11권2호
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• pp.19-47
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• 2012

Contemporary smartphone competition is generally described as the battle between Apple's proprietary platform and Google's open platform. However, this competition is not limited within smartphone adoption itself. User's pre-adoption of one mobile platform via smartphone can be connected to the post-adoption of the same mobile platform based on the other smart devices (e.g. smart pad). In this study, we investigate whether user's preference to a certain platform is persistent over mobile ecology, from the pre-adoption of one smart device to the post-adoption of following devices. For this investigation, we adopt the dual-model as the ground theory, where post-adoption of IT product is explained by both dedication and constraint factors. The empirical testing first evidences that dual model works well as our research model for identifying the reasons of post-adoption. Next, we group our data into two parts in order to compare the switching behavior of iPhone users and Android phone users. iPhone users show much lower switching rate to Android based smart pads, while Android phone users show higher churn rate to iPad (49.3% : 96.3%). Especially, satisfaction showed much stronger effect than switching cost on the continuing intention of existing platform, when the analysis is given to the iPhone user's group. From this result, we can conjecture the relatively stronger loyalty of iPhone users. More managerial implications on the mobile platform strategy are driven.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.158-164
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• 1999

This paper investigated and evaluated the NASA's Shuttle Imaging Radar-C (SIR-C) multiple frequency SAR data for differential backscattering effects of microwave from the surface geological materials overlying the skarn type mineralization. Although an integrated approach in mineral exploration is more cost effective and is well in use, there are still many technical and scientific issues to be further investigated and researched. In this study we have reprocessed several sets of previously surveyed exploration data and experimented with fuzzy logic digital fusion of the preprocessed data with respect to chosen exploration targets. Among the numerous fuzzy logic operators, which are currently available for a data driven integrated exploration strategy, we used varying combinations of fuzzy MIN, fuzzy MAX, and fuzzy SUM operators along with Gamma operator for fusion of exploration data, including the contact metamorphic zone information. The final exploration target tested was a skarn type W-Mo-F mineralization in the study area. The fuzzy logic derived mineral potential anomaly almost exactly matched the differential backscattering anomalies on the C-band and L-band SIR_C data when overlaid on each other. Although this high degree of correlation between these two data sets is remarkable, the differential backscattering anomaly over the skarn type W-Mo-F mineralization in the study area requires further investigation.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.609-617
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• 2016

Belt-driven Starter Generator (BSG) differs from other mild hybrid systems as the crankshaft of vehicle are not run off. Motor permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. Wound rotor synchronous motor (WRSM) could be adopted in BSG system for HEV e-Assisted application instead of the interior permanent magnet synchronous motor (IPMSM). In practice, adequate torque is indispensable for starter assist system, and energy conversion should be taken into account for the HEV or EV as well. Particularly, flux weakening control is possible to realize by adjusting both direct axis components of current and field current in WRSM. Accordingly, this paper present an off-line current acquisition algorithm that can reasonably combine the stator and field current to acquire the maximum torque, meanwhile the energy conversion is taken into consideration by losses. Besides, on account of inductance influence by non-uniform air gap around rotor, nonlinear inductances and armature flux linkage against current variation are proposed to guarantee the results closer to reality. A computer-aided method for proposed algorithm are present and results are given in form of the Look-up table (LUT). The experiment shows the validity of algorithm.

• 대한토목학회논문집
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• 제41권5호
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• pp.591-599
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• 2021

현재 국내 철도시설 운영기관은 노후 시설물 판단을 위한 명확한 정의와 시설물 보수/개량 우선순위 산정 방법이 정립되지 않아 성능중심 유지관리계획 수립에 어려움을 겪고 있다. 따라서, 본 연구는 선행연구에서 노후 시설물을 어떻게 정의하였는지 고찰하고, 국내 노후 철도시설물 관리제도와 미국 연방대중교통청(FTA)의 교통시설물 자산관리체계 비교분석을 통해 벤치마킹 포인트를 도출하였다. 노후 시설물 판단은 경과연수와 성능수준을 같이 고려해야 하며, 경과연수와 성능등급 간 관계를 통계적으로 분석하여 보수/개량 우선순위를 산정해야 한다. 또한, FTA와 같은 데이터 기반 철도시설 관리를 위해서는 표준 철도시설물 분류체계를 기반으로 시설물 분류 하위 수준에서 내용연수, 성능평가 결과, 유지관리비용 데이터베이스를 구축하는 것이 필요하다. 향후 데이터가 충분히 축적되면 성능중심 노후 철도시설 관리를 위한 효율적 예산집행계획 수립에 기여할 것으로 기대된다.