• 한국항행학회논문지
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• 제10권4호
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• pp.306-311
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• 2006

WiBro/WLAN Hierarchical 네트워크 구성 시 듀얼모드 단말기는 Hotspot 지역 이외의 WiBro 네트워크만 존재하는 지역에서도 Vertical 핸드오프를 위해서 항상 WLAN 모듈을 Power on 상태로 유지해야 한다. 핫스팟 지역이 아닌 WiBro 네트워크에서도 듀얼모드 단말기의 WLAN 모듈을 Power on 상태로 유지하기 때문에 사용자의 단말은 불필요한 전력을 소모하게 된다. 본 논문은 이를 보완할 수 있는 WiBro/WLAN Hierarchical 네트워크에서 듀얼모드 단말기의 Power Saving 전략에 관해 다루었다. 본 논문에서는 WiBro 네트워크 내의 핫스팟에 대한 정보를 이용하여 듀얼모드 단말기의 효율적인 Power Saving 전략을 수립하고자 한다.

• Journal of Construction Engineering and Project Management
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• 제2권2호
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• pp.28-35
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• 2012

Critical to project success is effective stakeholder management. This paper presents a challenge for the project manager who uses traditional approaches to manage mid-level stakeholders in an organization. Dual roles of a mid-level stakeholder (as a stakeholder of a project and as an agent of the corporate) may cause problems that would result in difficulties for project managers in identifying the stakeholder's attributes and overcoming hierarchical authority expectation. However, the dual roles of the stakeholder result in its weakness in the project-stakeholder relationship. Can a project leverage its strategic role for effective upward influence by linking project objectives to corporate strategic objectives? To address this research question, case study method was used to gain a deeper understanding of mid-level stakeholder's salience. This research proposes an upward influence strategy to embed a project-stakeholder relationship in a hierarchical stakeholder network.

• 경영과정보연구
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• 제38권2호
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• pp.105-118
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• 2019

기업이 수립한 전략이 효율적으로 실행되기 위해서는 적절한 조직문화가 뒷받침되어야 한다. 이는 전략실행에 적합한 조직문화를 갖추고 있을 경우 기업성과가 더욱 높아질 수 있음을 의미한다. 따라서 본 연구에서는 경쟁전략과 조직문화간의 적합성이 균형성과표 관점별 성과에 미치는 영향에 대해 분석해 보고자 한다. 경쟁전략을 원가우위전략과 제품차별화전략, 조직문화를 위계 합리문화, 합의 개발문화로 대별하고, KOSPI 상장 제조기업을 대상으로 설문조사를 통해 수집된 122부의 설문자료를 바탕으로 경쟁전략과 조직문화간의 적합성이 균형성과표 관점별 성과에 미치는 영향에 대해 실증 분석한 결과를 요약하면 다음과 같다. 첫째, 원가우위전략을 추진하는 기업의 경우 위계 합리문화의 적합성이 높은 것으로 나타났다. 구체적으로 원가우위전략과 위계 합리문화의 적합성이 높을수록 학습과 성장 관점 성과를 제외한 나머지 균형성과 표 관점별 성과가 더욱 높은 것으로 나타났다. 둘째, 제품차별화전략을 추진하는 기업의 경우 합의 개발문화의 적합성이 높은 것으로 나타났다. 구체적으로 제품차별화전략과 합의 개발문화의 적합성이 높을수록 모든 균형성과표 관점별 성과에 긍정적인 영향을 미치는 것으로 분석되었다. 본 연구는 기업이 수립한 전략의 성공적 추진을 위해서는 조직구성원의 신념 및 행동에 변화를 야기할 수 있는 조직문화를 전략에 적합하게 형성하는 것이 중요하다는 것을 실증적으로 규명해 보았다는데 연구의 의의를 찾을 수 있겠다.

• Journal of Power Electronics
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• 제18권5호
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• pp.1595-1607
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• 2018

In this paper, a hierarchical control strategy is introduced to control a new three-port multidirectional DC-DC converter for integrating an energy storage system (ESS) to a bipolar DC microgrid (BPDCMG). The proposed converter provides a voltage-balancing function for the BPDCMG and adjusts the states of charge (SoC) of the ESS. Previous studies tend to balance the voltage of the BPDCMG buses with active sources or by transferring power from one bus to another. Furthermore, the batteries available in BPDCMGs were charged equally by both buses. However, this power sharing method does not guarantee efficient operation of the whole system. In order to achieve a higher efficiency and lower energy losses, a triple-layer hierarchical control strategy, including a primary droop controller, a secondary voltage restoration controller and a tertiary optimization controller are proposed. Thanks to the multi-functional operation of the proposed converter, its conversion stages are reduced. Furthermore, the efficiency and weight of the system are both improved. Therefore, this converter has a significant capability to be used in portable BPDCMGs such as electric DC ships. The converter modes are analyzed and small-signal models of the converter are extracted. Comprehensive simulation studies are carried out and a BPDCMG laboratory setup is implemented in order to validate the effectiveness of the proposed converter and its hierarchical control strategy. Simulation and experimental results show that using the proposed converter mitigates voltage imbalances. As a result, the system efficiency is improved by using the hierarchical optimal power flow control.

• 한국정보과학회논문지:정보통신
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• 제29권5호
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• pp.466-472
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• 2002

본 논문에서는 계층적 셀 구조에서 umbrella 셀과 overlaid 셀 사이의 부하 분배 문제를 연구한다. 부하 분배 정책을 제안하고 HSDPA에서 인터넷 트래픽을 전달하는 경우를 시뮬레이션하여 제안된 정책의 성능을 평가한다. 평가 결과, 마이크로 셀이 피코 셀의 부하를 잘 분담해주는 것으로 나타났으며, 특히 특정한 피코 셀 집단에 큰 부하가 가해졌을 경우에 그 효과가 크게 나타났다. 이 정책을 사용할 경우, 비정상적인 큰 부하에 대처하기 위해 필요한 용량을 확보할 필요가 없어지므로 시스템 설치비용을 줄일 수 있게 된다.

• Journal of Power Electronics
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• 제19권4호
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• pp.989-999
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• 2019

This paper proposes a fault-tolerant control strategy with finite control set model predictive control (FCS-MPC) based on hierarchical optimization for five-level H-bridge neutral-point-clamped (5L-HNPC) inverter-fed induction motor drives. Fault-tolerant operation is analyzed, and the fault-tolerant control algorithm is improved. Adopting FCS-MPC based on hierarchical optimization, where the voltage is used as the controlled objective, called model predictive voltage control (MPVC), the postfault controller is simplified as a two layer control. The first layer is the voltage jump limit, and the second layer is the voltage following control, which adopts the optimal control strategy to ensure the current following performance and uniqueness of the optimal solution. Finally, simulation and experimental results verify that 5L-HNPC inverter-fed induction motor drives have strong fault tolerant capability and that the FCS-MPVC based on hierarchical optimization is feasible.

• 아동학회지
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• 제30권4호
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• pp.87-97
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• 2009

This study used Hierarchical Linear Modeling analysis to investigate the effects of individual self-regulated cognitive strategies and public education on middle school students' academic achievement. Participants were 6389 (boys 3287, girls 3102) middle school students from the 2005 data of the Korea Education Longitudinal Study. Results were as follows : (1) there were significant differences among different schools in middle school students' academic achievement, i.e. 20% of variance in English achievement and 15% of variance in mathematics achievement were explained by school differences. (2) Students' elaboration and meta-cognitive strategy influenced academic achievement positively. (3) Predictor variables by ability grouping, supplementary class, and/or self-learning class had no significant effects on students' academic achievement.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.471-472
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• 2007

At this paper, we use non reversible hierarchical scheme and fixed channel assignment scheme at the hierarchical cellular system with macrocell and microcell for the call process strategy Using this strategy, we analyze the system performance in accordance with the various dwell time at each cell. In this simulation result, the more the dwell time is small at microcell, the more the blocking probability and the handover failure probability is low.

• Journal of Information Processing Systems
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• 제10권4호
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• pp.555-567
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• 2014

Biometric performance improvement is a challenging task. In this paper, a hierarchical strategy fusion based on multimodal biometric system is presented. This strategy relies on a combination of several biometric traits using a multi-level biometric fusion hierarchy. The multi-level biometric fusion includes a pre-classification fusion with optimal feature selection and a post-classification fusion that is based on the similarity of the maximum of matching scores. The proposed solution enhances biometric recognition performances based on suitable feature selection and reduction, such as principal component analysis (PCA) and linear discriminant analysis (LDA), as much as not all of the feature vectors components support the performance improvement degree.

• Journal of Power Electronics
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• 제17권1호
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• pp.136-148
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• 2017

In recent years, voltage source multilevel converters are very popular in medium/high-voltage industrial applications, among which the NPC/H-Bridge converter is a popular solution to the medium/high-voltage drive systems. The conventional finite control set model predictive control (FCS-MPC) strategy is not practical for multilevel converters due to their substantial calculation requirements, especially under high number of voltage levels. To solve this problem, a hierarchical model predictive voltage control (HMPVC) strategy with referring to the implementation of g-h coordinate space vector modulation (SVM) is proposed. By the hierarchical structure of different cost functions, load currents can be controlled well and common mode voltage can be maintained at low values. The proposed strategy could be easily expanded to the systems with high number of voltage levels while the amount of required calculation is significantly reduced and the advantages of the conventional FCS-MPC strategy are reserved. In addition, a HMPVC-based field oriented control scheme is applied to a drive system with the NPC/H-Bridge converter. Both steady-state and transient performances are evaluated by simulations and experiments with a down-scaled NPC/H-Bridge converter prototype under various conditions, which validate the proposed HMPVC strategy.