• Journal of Power Electronics
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• 제16권6호
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• pp.2284-2293
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• 2016

With the rapid development of clean energy, photovoltaic (PV) generation has been utilized in the harmonic compensation of power systems. This paper presents a novel multi-function PV micro-inverter with three stages (pseudo-two-stage). It can inject active power and compensate harmonic currents in the power grid at the same time. In order to keep the micro-inverter working under the maximum allowable output power, an optimized capacity limitation strategy is presented. Moreover, the harmonic compensation can be adjusted according to the customized requirements of power quality. Additionally, a phase shedding strategy in the DC/DC stage is introduced to improve the efficiency of parallel Boost converters in a wide range. Compared with existing capacity limitation methods, the proposed strategy shows better performance and energy efficiency. Simulations and experiments verify the feasibility of the micro-inverter and the effectiveness of the strategy.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.876-881
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• 1998

The compensation strategy of shunt active power filters is one of the most important link that determine its compensation characteristics. In this paper, a new interpretation of the instantaneous reactive power theory in three-phase circuits was proposed. A compensation strategy (ip, iq mode) was introduced on the basis of the new interpretation. This compensation strategy was compared with other two compensation strategies(P, q mode and UPF mode). When source voltage is distorted, a sinusoidal, the three compensation strategies are equivalent to each other. When source voltage is distorted, a sinusoidal source current may result only by using ip, iq mode. This is the advantage of ip, iq mode. The result is verified by simulation.

• 산업융합연구
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• 제20권11호
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• pp.105-112
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• 2022

본 연구의 목적은 경영자의 능력과 경영자 성과-보상 민감도 간의 관련성에 보고이익전략이 미치는 조절효과를 살펴보는 것이다. 경영자의 보고이익전략에 따른 경영성과의 조정 방향은 상향조정과 하향조정 모두 발생할 수 있으며, 상향 조정과 하향 조정에 따라 경영자 보상에 미치는 영향이 차별적일 것으로 예상되어 분석한 결과, 과대보고를 위한 보고이익전략은 기대와 동일하게 상향조정 된 경영성과에 따라 보상을 지급하였으므로 성과에 근거한 차별적인 보상이 지급되지 않는 것으로 확인되었다. 반면에 과소보고를 위한 전략은 성과에 근거한 성과-보상 민감도를 감소시키는 것으로 나타났다. 과소보고전략은 경영자의 능력에 따른 보고전략의 수행에 대하여 추가적인 보상이 지급되어 보상의 수준은 증가하지만, 이러한 유형의 보상이 경영자의 실제 성과와는 무관하므로 성과-보상 민감도를 감소시킬 것이라는 가설을 지지하며, 보고이익전략에 따른 경영성과의 상향 및 하향 조정에 대해 차별적인 보상이 이루어진다는 것을 간접적으로 확인한 결과이다.

• Journal of Power Electronics
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• 제14권2호
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• pp.383-391
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• 2014

For the digital control of systems such as grid-connected inverters, measuring inverter output currents accurately is essential. However, current measurement offsets are inevitably generated by current measurement paths and cause DC current components in real inverter output currents. Real inverter output currents with DC components cause the DC-link capacitor voltage to oscillate at the frequency of a utility voltage. For these reasons, current measurement offsets deteriorate the overall system performance. A compensation strategy to eliminate the effect of current measurement offsets in grid-connected inverters is proposed in this study. The validity of the proposed compensation strategy is verified through simulations and experiments. Results show that the proposed compensation strategy improves the performance of grid-connected inverters.

• 산업경영시스템학회지
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• 제27권4호
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• pp.33-41
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• 2004

This study examines the relationship between multiple sales force management practices and performance within each of Miles & Snow (1978)'s strategy types and Walker & Ruekert (1987)'s strategy types. The findings are as follows : First, Prospectors seem to be associated with increased performance when they are utilizing a relationship selling strategy, internal sales force, moderate levels of supervision, outcome-based control system and incentive-oriented compensation system. Second, Analyzers seem to be associated with increased performance when they are utilizing a relationship selling strategy, internal sales force, outcome-based control system to deal with the instability in their strategic focus. Third, Low Cost Defender seem to be associated with increased performance when they are utilizing a relationship selling strategy, external sales force, low levels of supervision, outcome-based control system and salary-oriented compensation system. Fourth, Differentiated Defenders seem to be associated with increased performance when they are utilizing a relationship selling strategy, high levels of supervision, balanced (outcome+behavior) control system and salary-oriented compensation system.

• 전기학회논문지
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• 제57권10호
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• pp.1696-1702
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• 2008

This paper proposes a voltage compensation device direct control strategy to realize the distributed, autonomous voltage control of the distribution system, which based on voltage data collected from customers of the remote site under the ubiquitous-based distribution system. In the proposed method, The ULTC and the SVR(Step Voltage Regulator)s compensate autonomously the voltage for self-compensation area based on the voltage data furnished from the ubiquitous device of customers. Also, the SVRs overcome the limit of single-operation of ULTC by the interlocking operation with the ULTC and enhance the voltage compensation capability for the customer. In particular, an optimization design method and a fuzzy design method are compared to determine the effective control method of the voltage compensator under the ubiquitous-based on-line operation environments. In fuzzy method, the tap of voltage compensator is defined as output member. Finally, the proposed two methods are implemented in Visual C++ MFC, the effectiveness is proved by simulation based on the worst virtual voltage data. Also, an optimal voltage compensation strategy is determined under on-line environments based on analyzed results.

• 산업기술연구
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• 제20권B호
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• pp.175-182
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• 2000

In this paper, a novel speed control strategy using an acceleration feedforward compensation by the estimation of the system inertia is proposed. With the proposed method, the enhanced speed control performance can be achieved and the speed response against the disturbance torque can be improved for the vector-controller induction motor drive systems in which the bandwidth of the speed controller cannot be made large enough. The experimental results confirm the validity of the proposed strategy.

• 영어어문교육
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• 제17권1호
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• pp.165-190
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• 2011

This research investigates listening strategies and the relationship between the employment of strategy and listening proficiency of Korean EFL middle school students. One hundred and four middle school students (N = 104) participated in this study and their strategy use was assessed through a questionnaire adapted from Oxford's (1990) SILL and O'Malley and Chamot (1990). To measure listening proficiency, the English Listening Ability Test designed by 15 city and provincial offices of education in Korea was used. The results show that students employed a moderate use of strategies; compensation strategies were used most frequently and metacognitive strategies were used the least frequently. Significant differences were found in the use of implicit strategy among different listening proficiency groups, but not in their use of behavioral strategy. Furthermore, there were significant differences in the use of implicit memory, cognitive and compensation strategies among groups of students with different listening proficiencies, but not in their use of metacognitive strategy. The results from multiple regression analysis indicate that implicit strategy use could play an important role in listening comprehension. The findings suggest the need for additional research to explore the effect of listening strategy training for English language learners.

• Journal of Power Electronics
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• 제15권5호
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• pp.1348-1357
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• 2015

Under traditional unified power quality conditioner (UPQC) control, a UPQC series converter (SC) is mainly used to handle grid-side power quality problems while its parallel converter (PC) is mainly used to handle load-side power quality problems. The SC and PC are relatively independent. The SC is usually in standby mode and it only runs when the grid voltage abruptly changes. In this paper, novel UPQC coordinated control strategies are proposed which use the SC to share the reactive power compensation function of the PC especially without grid-side power quality problems. However, in some cases, there will be a circulating current between the SC and the PC, which will probably influence the compensation fashion, the compensation capacity, or the normal work of the UPQC. Through an active power circulation analysis, strategies with and without a circulating current are presented which fuses the reactive power allocation strategy of the SC and the PC, the composite control strategy of the SC and the compensation strategy of the DC storage unit. Both of the strategies effectively solve the SC long term idle problem, limit the influence of the circulating current, optimize all of the UPQC units and reduce the production cost. An analysis, along with simulation andexperimental results, is presented to verify the feasibility and effectiveness of the proposed control strategies.

• Journal of Power Electronics
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• 제17권3호
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• pp.798-810
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• 2017

This paper presents a combined system of a small-capacity inverter and multigroup delta-connected thyristor switched capacitors (TSCs). The system is referred to as a hybrid static compensator (HSC) and has the functions of dynamic reactive power compensation and harmonic suppression. In the proposed topology, the load reactive power is mainly compensated by the TSCs. Meanwhile the inverter is meant to cooperate with TSCs to achieve continuous reactive power compensation, and to filter the harmonics generated by nonlinear loads and the TSCs. First, the structure and mathematical model of the HSC are discussed Then the control method of the HSC is presented. An improved reduced order generalized integrator (ROGI)-based selective current control method is adopted in the inverter to achieve high-performance reactive and harmonic current compensation. Meanwhile, a switch control strategy is proposed to implement precise and fast switching of the TSCs and to avoid changing the time delay needed by the conventional switch strategy. Experiments are implemented on a 20 KVA HSC prototype and the obtained results verify the validity of the proposed HSC system.