• 산업노동연구
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• 제24권2호
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• pp.409-441
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• 2018

이 글은 미국 최대 독립 정유회사인 Valero Energy에 대한 사례연구로서, 비노조 기업의 기업문화와 인적자원관리의 특징을 살펴보기 위한 목적 하에 작성되었다. 1980년 설립 이래 Valero는 유전지역인 텍사스 기반 지역기업으로서 남부지역 정서에 부합하는 비노조기업 성격이 뚜렷하다. 강력한 CEO 리더십, 종업원 최우선 정책과 팀워크 강조 문화, 확고한 고용보장정책(no lay-off policy) 및 인사업무 외주화 금지 정책, 업계 중상위권의 임금수준과 업계 최고 수준의 복리후생, 비노조전통과 이를 보완하는 공정한 고충해결 시스템 구비 노력 등 미국 비노조기업의 인적자원관리 특징들을 잘 보여주는 전형적인 예에 해당한다. 2010년 이전까지 엄청난 성장과 수익성 제고에 기반하여, 한계기업이 선호하는 노조압박방식 대신, 우량기업이 채택하는 노조대체방식을 노조회피전략의 구체적인 방안으로 실행하여 왔다. 하지만, 최근 들어, 지속적인 인수합병으로 인한 기업 인력 내 이질성 확대, 유가 하락 등으로 인한 고용보장정책 유지의 어려움과 정리해고 실시 필요성 증대 등으로 인해 Valero의 노조대체방식에 기반한 노조회피전략은 본격적인 시험대에 올라가고 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권3호
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• pp.941-955
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• 2015

In dual-channel networks (DCNs), all frequency hopping (FH) sequences used for data channels are chosen from the original FH sequence used for the control channel by shifting different initial phases. As the number of data channels increases, the hitting frequency point problem becomes considerably serious because DCNs is non-orthogonal synchronization network and FH sequences are non-orthogonal. The increasing severity of the hitting frequency point problem consequently reduces the resource utilization efficiency. To solve this problem, we propose a novel hitting frequency point collision avoidance method, which consists of a sequence-selection strategy called sliding correlation (SC) and a collision avoidance strategy called keeping silent on hitting frequency point (KSHF). SC is used to find the optimal phase-shifted FH sequence with the minimum number of hitting frequency points for a new data channel. The hitting frequency points and their locations in this optimal sequence are also derived for KSHF according to SC strategy. In KSHF, the transceivers transmit or receive symbol information not on the hitting frequency point, but on the next frequency point during the next FH period. Analytical and simulation results demonstrate that unlike the traditional method, the proposed method can effectively reduce the number of hitting frequency points and improve the efficiency of the code resource utilization.

• 시스템엔지니어링학술지
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• 제15권1호
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• pp.25-33
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• 2019

In the plant industry, the share of equipment accounts for 45 ~ 75%, which is very high. It is a traditional plant centered on processes and reactions like petroleum and chemical plants. Renewable energy generation plants such as wind power generation and solar power generation are equipment-centric plants. Equipment-centric plants are very important not only in the EPC phase but also in the operation and management phase. The procurement of equipment for plant operation and management can be divided into make and buy. Make is a method of producing equipment itself, and buy is a method of procuring equipment from the outside. The procurement method of the equipment directly affects the plant operation and management cost. In this study, the decision making of equipment procurement method for plant operation and management is defined as 4 phase. Each phase is selection of procurement decision-making objects, technology strategy perspective, finance perspective, and production perspective. In detail, we defined selection process of procurement decision-making objects and technology strategy perspective process. We will contribute to the enhancement of the competitiveness of the plant operation and management area by carrying out researches on the process and application examples of financial and production perspectives in the future.

• Journal of Power Electronics
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• 제19권3호
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• pp.727-743
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• 2019

This paper presents a pulse-width modulation strategy to eliminate the common mode voltage (CMV) with reduced CMV spikes in multilevel inverters since a high CMV magnitude and its fast variations dv/dt result in bearing failure of motors, overvoltage at motor terminals, and electromagnetic interference (EMI). The proposed method only utilizes the zero CMV states in a space vector diagram and it is implemented by a carrier-based pulse-width modulation (CBPWM) method. This method is generalized for odd number levels of inverters including neutral-point-clamped (NPC) and cascaded H-bridge inverters. Then it is extended to the over-modulation mode. The over-modulation mode is implemented by using the two-limit trajectory principle to maintain linear control and to avoid look-up tables. Even though the CMV is eliminated, CMV spikes that can cause EMI and bearing current problems still exist due to the deadtime effect. As a result, the deadtime effect is analyzed. By taking the deadtime effect into consideration, the proposed method is capable of reducing CMV spikes. Simulation and experimental results verify the effectiveness of the proposed strategy.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.452-464
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• 2015

This paper proposes a DC microgrid operational strategy and control method for improved service reliability. The objective is to supply power to as many non-critical loads as possible, while providing an uninterrupted power supply to critical loads. The DC bus signaling method, in which DC voltage is an information carrier, is employed to implement the operational strategy in a decentralized manner. During grid-connected operation, a grid-tied converter balances the power of the microgrid by controlling the DC voltage. All loads are connected to the microgrid, and operate normally. During islanded operation, distributed generators (DGs), a backup generator, or an energy storage system balances the power. However, some non-critical loads may be disconnected from the microgrid to ensure the uninterrupted power supply to critical loads. For enhanced service reliability, disconnected loads can be automatically reconnected if certain conditions are satisfied. Control rules are proposed for all devices, and detailed microgrid operational modes and transition conditions are then discussed. Additionally, methods to determine control parameter settings are proposed. PSCAD/EMTDC simulation results demonstrate the performance and effectiveness of the proposed operational strategy and control method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.721-723
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• 1993

A PWM switching control strategy based on instantaneous integration concept for reducing hamonic components of inverter system with fluctuating input voltage is presented. Applying this strategy to single phase full bridge PWM inverter through bipolor switching method and unipolor switching method, reduction of hamonic components of output voltage and current is demonstrated through simulation. The system operation is examined and confirmed by experiments.

• 제어로봇시스템학회논문지
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• 제6권12호
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• pp.1079-1085
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• 2000

In this paper, we propose a method of cooperative control (T-cell modeling) and selection of group behavior strategy (B-cell modeling) based on immune system in distributed autonomous robotic system (DARS). An immune system is the living bodys self-protection and self-maintenance system. these features can be applied to decision making of the optimal swarm behavior in a dynamically changing environment. For applying immune system to DARS, a robot is regarded as a B-cell, each environmental condition as an antigen, a behavior strategy as an antibody, and control parameter as a T-cell, respectively. When the environmental condition (antigen) changes, a robot selects an appropriate behavior strategy (antibody). And its behavior strategy is stimulated and suppressed by other robots using communication (immune network). Finally, much stimulated strategy is adopted as a swarm behavior strategy. This control scheme is based on clonal selection and immune network hypothesis, and it is used for decision making of the optimal swarm strategy. Adaptation ability of the robot is enhanced by adding T-cell model as a control parameter in dynamic environments.

• 전기학회논문지P
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• 제51권4호
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• pp.206-210
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• 2002

The transmission delays in the networked control systems affect the performance and stability. For covering the delays, this paper proposes NCS including the predictive strategy. The proposed method shows that the two cases such as stable and unstable system are well behaved.

• 한국컴퓨터정보학회논문지
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• 제22권10호
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• pp.129-135
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• 2017

This research is to identify an easy and effective method of teaching-learning plan. The teaching-learning plan is a blue_print applied for designing effective lessons. However, most of the teachers regard it as a difficult and inefficient job. This study proposed the concrete instructional model framework as a tool to develop the teaching-learning plan easily and effectively. The concrete instructional model framework will represent a decomposed instructional strategy applied for each step of the instructional model developed by educational researchers. This method is applied to develop a computer teaching-learning plan. Therefore, the proposed method will expand an easier teaching-learning plan. Furthermore, the proposed method develops a teaching-learning plan with fluent content in detail based on low-level instruction strategies applied in the concrete instruction model framework.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2004년도 추계학술대회
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• pp.259-267
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• 2004

Enterprise must establish a properly competitive strategy according to environmental changes and international competitions. It is necessary to develop the strategy of competitive power for an efficient operation as well as system, industry, product and price competitions. This paper aims to propose a choice method of Competitive Power Key Factors which can be applied to unit parts and finished products, construction products, soft wear products based on Reliability.