• Journal of Power Electronics
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• 제15권1호
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• pp.235-245
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• 2015

This paper proposes a reactive current assignment and control strategy for a doubly-fed induction generator (DFIG) based wind-turbine generation system under generic grid voltage sag or swell conditions. The system's active and reactive power constrains during grid faults are investigated with both the grid- and rotor-side convertors (GSC and RSC) maximum ampere limits considered. To meet the latest grid codes, especially the low- and high-voltage ride-through (LVRT and HVRT) requirements, an adaptive reactive current control scheme is investigated. In addition, a torque-oscillation suppression technique is designed to reduce the mechanism stress on turbine systems caused by intensive voltage variations. Simulation and experiment studies demonstrate the feasibility and effectiveness of the proposed control scheme to enhance the fault ride-through (FRT) capability of DFIG-based wind turbines during violent changes in grid voltage.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권4호
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• pp.1538-1552
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• 2021

Machine learning models are vulnerable to adversarial examples generated by adding a deliberately designed perturbation to a benign sample. Particularly, for automatic speech recognition (ASR) system, a benign audio which sounds normal could be decoded as a harmful command due to potential adversarial attacks. In this paper, we focus on the countermeasures against audio adversarial examples. By analyzing the characteristics of ASR systems, we find that frame offsets with silence clip appended at the beginning of an audio can degenerate adversarial perturbations to normal noise. For various scenarios, we exploit frame offsets by different strategies such as defending, detecting and hybrid strategy. Compared with the previous methods, our proposed method can defense audio adversarial example in a simpler, more generic and efficient way. Evaluated on three state-of-the-arts adversarial attacks against different ASR systems respectively, the experimental results demonstrate that the proposed method can effectively improve the robustness of ASR systems.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.785-792
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• 2024

This article provides an overview of the design methodology used to develop a conceptual set of reactivity control mechanism of a micro reactor based on the U-Battery. The U-Battery is based on remote deployment and therefore it is favourable to provide a long fuel lifecycle. This is achieved by implementing a high fissile loading content, which proves challenging when considering reactivity control methods. This article follows the design methodology used to overcome these issues, with an emphasis on a new concept of a moveable moderator which utilises the size of the U-Battery as a small reduction in moderation provides a significant reduction in reactivity. The latest work on this project sees the moveable moderator investigated during a depressurised loss of forced coolant accident, where a reduction of moderator volume increases the maximum fuel temperature experienced. The overall conclusion is that the maximum fuel temperature is not significantly increased (4 K) due to the central reflector region relatively lower volumetric heat capacity compared to that of whole core. However, a small temperature increase is observed immediately after the transient due to the central reflector removal because it reaches energy equilibrium with the fuel region faster.

• International Journal of Quality Innovation
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• 제7권2호
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• pp.50-68
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• 2006

Innovation fuels organizations evolving them to withstand rapid changes in markets and challenges from competition. While diversified concepts of innovation are examined, a generic framework for managing organizational innovation is established to portray the notion in a methodical approach. Substantiation of the determinants for organizational innovation is carried out in order to examine the framework against the practical situation. Subsequently, expectations and actual accomplishments of the determinants for organizational innovation from the industry are determined so as to understand the industrial view towards the framework. This paper summarizes the empirical findings of a survey of organizational innovation with a sample of 208 electronic and electrical manufacturing companies in the Greater Pearl River Delta (GPRD), China. On one hand, the survey findings confirm the readiness of the generic framework from the practical perspective of the industry. On the other hand, rankings are obtained for the expected importance and company accomplishment of the determinants for organizational innovation, namely in the areas of management leadership and commitment, employee capability and attitude and strategy development for innovation. The improvement area is also verified by the shortcomings of the expectation in comparison to the company accomplishment in each determinant. Meanwhile, it is believed that a directional attitude towards the determinants can facilitate the accomplishment of the determinants of organizational innovation. Further results will be generated from a more in-depth analysis of variables. The confirmed framework will be further developed into an assessment system for organizational innovation with the support of best practices in each determinant.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.58-73
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• 2021

Cloud Service Providers (CSPs) enable their users to access Cloud computing and storage services from anywhere in quick and flexible manners through the Internet. With the basis of 'pay-as-you-go' model, it makes the interactions between CSPs and the users play a vital role in shaping the Cloud computing market. A pool of virtualized and dynamically scalable Cloud services that delivered on demand to the users is associated with guaranteed performance and cost-provisioning. It needed a costing scheme for determining suitable charges in order to secure lease pricing of the Cloud services. However, it is hard to meet the satisfied prices for both CSPs and users due to their conflicting needs. Furthermore, there is lack of Service Level Agreements (SLAs) that allowing the users to take part into price negotiating process. The users may lose their interest to use Cloud services while reducing CSPs profit. Therefore, this paper proposes a generic costing scheme for Cloud services using General Equilibrium Theory (GET). GET helps to formulate the price function for various services' factors to match with various demands from the users. It is initially determined by identifying the market circumstances that a general equilibrium will be hold and reached. Specifically, there are two procedures of agreement made in response to (i) established equilibrium supply and demand, and (ii) service price formed and constructed in a price range. The SLAs in our costing scheme is integrated to satisfy both CSPs and users' needs while minimizing their conflicts. The price ranging strategy is deliberated to provide prices' options to the users with respect their budget limit. Meanwhile, the CSPs can adaptively charge based on users' preferences without losing their profit. The costing scheme is testable and analyzed in multi-tenant computing environments. The results from our simulation experiments demonstrate that the proposed costing scheme provides better users' satisfaction while fostering fairness pricing in the Cloud market.

• Nuclear Engineering and Technology
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• 제27권2호
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• pp.203-215
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• 1995

소형냉각재 상실사고시 원자로냉각재펌프( RCP )의 지속적인 운전은 원자로냉각재의 불필요한 누출을 초래하여 심각한 노심노출 및 이에따른 핵연료 손상을 야기시킬 수 있다. TMI 사고 후 미국 NRC의 요구에 따라 CE형 발전소 사용자 단체에서는 “T2/L2”라는 RCP 트립전략을 개발하여 CE형 발전소에 적용 가능토록 일반비상운전지침서에 반영하였다. 상기 T2/L2 RCP 트립전략은 사고후 원자로 냉각재 계통의 압력이 감소하여 RCP 트립설정치에 도달하면 처음 두대의 RCP를 우선 정지시키고, 사고가 LOCA임이 확인되면 나머지 두대의 RCP를 정지시키는 방식을 채택하고 있다. 본 논문에서는 영광3, 4호기의 RCP 트립설정치를 분석, 선정하고 T2/L2 전략의 안전운전양상을 입증하였다 분석결과, 최악의 파단크기로 밝혀진 0.15 ft$^2$의 고온관 파단 LOCA 영광3, 4호기 RCP 트립설정치는 가압기 압력 1775 psia로 나타났으며, 운전원이 마지막 두대의 RCP를 트립시키지 못하였을 경우 혹은 최악의 시점에서 정지시켰을 경우에도 영광3, 4호기의 노심냉각능력은 확보될 수 있음이 확인되었다. 또한 영광3, 4호기의 RCP 트립전략은 미국 NRC가 요구하는 최대 핵연료피복재온도 관점에서의 10 CFR 50.46 요구조건과 운전원 조치시간 관점에서의 ANSI 58.8 요구조건도 충분히 만족함이 판명되었다 따라서, 1775 psia의 RCP 트립설정치를 사용한 영광3, 4호기의 T2/L2 RCP 트립전략은 사고시 운전원에게 향상된 운전지침을 제공할 수 있을 것으로 판단된다.

• 한국산학기술학회논문지
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• 제19권9호
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• pp.435-445
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• 2018

본 연구는 자동차 부품 기업이 수출다변화 전략을 수립함에 있어서 고려할 영향요인과 전략의 중요도와 우선순위를 분석하였다. 기업의 수출다변화 전략은 기업이 보유하고 있는 내부 역량과 외부 환경을 중심으로 결정되어 왔다. 선행문헌을 리뷰하고, 전문가 6명을 대상으로 인터뷰를 실시하였다. 문헌 리뷰와 인터뷰 결과를 교차분석하여 영향요인을 선정하였으며, 다기준 의사결정 기법인 AHP(Analytic Hierarchy Process)을 활용 분석하였다. 설문조사는 수출업무경험을 갖고 있는 자동차 부품기업 재직자 87명을 대상으로 전자메일 및 직접조사를 통해서 수행하였고, 최종 68명의 설문이 유효하였다. 이를 분석한 결과, 영향요인들의 상대적 중요도와 우선순위를 결정하였다. 영향요인간 쌍대비교를 하고 이들의 상대적 중요값을 결정하였다. 그리고 대안으로는 Porter(1985)의 본원적 경쟁전략 이론을 근거로 하였다. 분석결과, 중요도는 평균적으로 내부역량, 상호관계, 구매자 영향, 진입장벽, 기술력 대응, 경쟁환경 순으로 나타났다. 해외 브랜드 수준이 높은 권역은 제품차별화, 저원가, 집중화 순이며, 수준이 낮은 권역은 저원가, 제품차별화, 집중화 순으로 나타났다. 본 연구결과는 자동차부품 중소기업이 수출다변화 전략 채택을 위한 대안을 마련하여 상황에 맞는 전략을 수립할 수 있다는 것에 의미가 있다. 자동차부품 수출 다변화는 세계권역별 다양한 특성의 맞춤형 전략 수립이 필요하며, 또한 수출다변화를 위한 내부역량 뿐만아니라 동시에 현지 구매자와 그 상호관계가 중요한 것으로 분석되었다.

• 한국게임학회 논문지
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• 제9권2호
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• pp.59-68
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• 2009

본 연구는 게임엔진 공급자의 기술체제와 기술혁신에 따른 Licensing 전략을 실증적으로 분석하였다. 분석 결과 게임엔진 공급자의 기술체제가 이질적으로 분화되고, 게임엔진의 기술체제가 이용자 친화적일수록 게임 개발기업(user)의 거래가 증가하였다. 게임엔진 공급자의 Licensing 전략을 결정하는 기술지식 변수로는 엔진 공급자의 기술체제의 이용자 친화성(User Friendliness)이 가장 설명력이 높다. 공급자의 엔진 구조의 모듈화, 게임엔진의 범용성, 암묵적(tacit) 기술지식의 명시화(cordifiablity), 게임엔진의 혁신정도가 클수록 엔진기술지식의 지원역량이 증가되고, 동시에 엔진기술의 거래 비용이 감소함에 따라 불완전한 게임기술시장에서 효율적인 시장거래가 이루어지고 있다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.607-610
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• 2004

It is still not sufficient for the famous embedded software test methods such as Finite State Machine, Software Cost Reduction and model coverage based test case generation, to pinpoint where bugs hang around and to figure out what makes the bugs. A new approach to ameliorate the drawbacks is proposed in this paper. In the approach, we define a generic model for embedded software. And we also define failure mechanism for embedded software, and a way to generate test cases based on it.

• 약학회지
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• 제56권2호
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• pp.116-125
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• 2012

Local pharmaceutical companies in Korea, which have grown focusing on domestic markets, have recently faced difficulties such as market saturation, price control policies and market-opening pressures by FTA. It seems to be an urgent issue for them to export pharmaceuticals to developed countries comprising the greater part of the global pharmaceutical market. Hence, this research was conducted to investigate and benchmark the strategies employed by India industry for the successful access to the global pharmaceutical markets. Drug policies as well as their influences on pharmaceutical market changes between India and Korea for the last 40 years have been searched and the differences have been comparatively analyzed. The pharmaceutical industry of India has the following strengths: low costs; experienced labor pool; excellent reverse-engineering skills; powerful IT; marketing capability; and established distribution network. After 2000, consolidations, M&A and alliances with domestic and multinational companies have been sharply increased in the industry of India. Indian companies unfolding both competition and cooperation with multinational corporations currently move up the value-added chain, and this enthusiastic strategy should be learned by local pharmaceutical companies.