• 대한전기학회논문지
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• 제35권12호
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• pp.541-554
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• 1986

This paper presents the results of driving performance analysis of permanent magnet synchronous motor using a microprocessor based control system. The system consists of three phase power transistor inverters, three phase controlled rectifier, three central processing units, and sensors. The three CPUs are, respectively, used to generate PWM control signals for the inverter generating three phase sine wave, to generate the gate control signals for firing the converter, and to supervise other two CPUs. The supervisor is used to compute PI control algtorithm to three phase reference sine wave for the inverter. It is also used to maintain a constant voltage frequency ratio for the converter operating as a constant torque controller. The inverter CPU retrieves precomputed PWM patterns from look up tables because of computation speed limitations found in almost available microprocessors. The converter CPU also retrieves precomputed gate control patterns from another look-up tables. For protecting the control ststem from any damage by extraordinary over currents, the supervisor receives the data from current sensor, CT, and break down the CB to isolate the circuits from source. A resolver has a good performance characteristics of overall speed range, especially on low speed range. Therefor the speed control accuracy is impoved. The microprocessor based PM synchronous motor control system, thus, has many advantages such as constant torque characteristics, improvement of wave, limitation on extraordinary over currents, improvement of speed control accuracy, and fast response speed control using multi-CPU and look-up tables.

• 품질경영학회지
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• 제46권3호
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• pp.551-568
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• 2018

Purpose: This study addressed the relationship between technological innovation activity and management efficiency of Korean automobile firms. We tested the hypothesis of non-liner relationship of innovation activity in relation to management efficiency. Methods: We discussed prior literature in the firm innovation strategy and management efficiency studies to provide better understanding of relationships between technological innovation activity and management efficiency. As a result, we developed develop and tested a model (Inverted-U shaped) capturing the non-linear impact of technological innovation activity. While we used R&D expenditure and patent registration data for measuring firms' innovation activity, management efficiency was evaluated by using DEA(Data Envelopment Analysis). Results: Main findings of our empirical analysis indicated that the relationships between technological innovation activity and management efficiency was inverted U shaped. This implied that the relationship between technological innovation and management efficiency is inverted U-shaped non-linear, with management efficiency increasing up to a point, beyond which higher levels of R&D and patent registration activities led to a decrease in management efficiency. Conclusion: This study empirically assessed the inconclusive findings of previous research in the area of effects of innovation activities in relation to firm performance. The paper also provided theoretical and practical implications for firms who explore efficient strategy to promote the management performance through technological innovation activities. Future research directions with the limitation of the study was discussed.

• 한국멀티미디어학회논문지
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• 제13권4호
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• pp.496-503
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• 2010

어휘인식 시스템은 스탠드 얼론(Standalone)으로 개발되어 지고 있으며 휴대용 단말기에서 사용하였을 경우 메모리 공간의 제약과 오디오 압축으로 인해 인식률이 낮게 나타난다. 본 연구에서는 휴대용 단말기의 성능과 인식률 향상을 위하여 음향학적 탐색과 언어적 탐색을 분리하여 어휘 인식 속도를 개선한 시스템을 제안하였다. 음향학적 탐색은 휴대용 단말기에서 수행하고 보다 복잡한 언어적 탐색은 서버에서 처리하는 시스템으로 음성신호로부터 특징벡터를 추출하여 GMM을 이용한 음소인식을 수행하고, 인식된 음소 열을 서버로 전송하여 렉시컬 트리 탐색 알고리즘을 사용하여 언어적 탐색 단계에서 어휘 인식을 수행하였다. 시스템 성능 평가 결과 어휘 종속 인식률은 98.01%, 어휘 독립 인식률은 97.71%의 인식률을 나타냈으며 인식속도는 1.58초로 나타내었다.

• Asia pacific journal of information systems
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• 제25권3호
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• pp.473-499
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• 2015

The limited literature on Open Source Software (OSS) customers' adoption does not provide explanations on how OSS services are adopted by customers in the presence of functionally superior commercially licensed software (CLS). This paper aims to uncover the process that shapes customer satisfaction of OSS services in comparison to CLS. Expectation Disconfirmation Theory (EDT) is adapted and integrated with pre implementation factor model that influences software customers' expectations including cost, reputation, and experience. The constructed research model is empirically validated using a field survey of OSS and CLS database management system (DBMS) customers in Korea. The theoretical contribution of the paper lies on the application of EDT to explain the wide adoption of OSS DBMS services in the presence of functionally superior CLS DBMSs. Furthermore, this paper integrates EDT with pre-implementation factors for customers' expectations, which has been considered a limitation of the theory. Among the practical contributions, this study draws attention to the substantive differences between OSS and CLS customers' expectations. Additionally, it offers initial explanations for the differences in customer behavior for OSS and CLS and the way that customers' expectations and actual performance are mingled together to form customer satisfaction.

• 한국자동차공학회논문집
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• 제17권4호
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• pp.24-31
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• 2009

This paper has been focused on the development of integrated automotive muffler system to meet getting more stringent sound quality target. Typically, muffler system consists of resonator and main muffler. The many varieties in exhaust pipe routing and the flexibility in muffler design make it possible to design an exhaust system to deliver tailpipe sound for specific sound quality requirement. In recent, it is strongly recommended that the function of resonator be merged into that of main muffler due to severe space limitation of underbody. The main objective of the paper is to study the effects of various geometrical parameters on the muffler performance. This work has succeeded in eliminating resonator without loss of muffler performance. This work has also investigated the effect of diameter of hole, geometries of pipes and location of muffler on the sound quality.

• Structural Engineering and Mechanics
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• 제61권6호
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• pp.737-746
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• 2017

The touch down zone (TDZ) and top connection point of the vessel are most critical part of fatigue damage in the steel catenary riser (SCR). In general, the linear soil model has been used to evaluate fatigue performance of SCRs because it gives conservative results in the TDZ. However, the conservative linear soil model shows the limitation to accommodate real behavior in the TDZ as water depth is increased. Therefore, the riser behavior on soft clay seabed is investigated using a nonlinear soil model through time domain approach in this study. The numerical analysis considering various important parameters of the nonlinear soil model such as shear strength at mudline, shear strength gradient and suction resistance force is conducted to check the adoptability and applicability of nonlinear soil model for SCR design.

• 한국IT서비스학회지
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• 제17권2호
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• pp.179-190
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• 2018

This study is about the influence of authors' centrality on research outcomes in a large-scale collaborative research network. Using the social network analysis method, five types of centralities were derived. Six research outcomes of individual researchers were also derived through bibliographic information of the social science field for the last 10 years. A multivariate regression analysis was conducted to examine the causal relationship between the centrality and research outcome, and the effect of centrality on research outcomes was found to be statistically significant. The result of this study shows that the revised citation and H-index significantly influenced the authors' centrality. This result can imply that the centrality of the researcher can expect a considerable influence of the thesis as well as a certain level of productivity. The meaning of this study is to analyze the effect of centrality on the research outcomes of the large-scale collaborative research network in the past decade, and is carefully to suggest a guideline in order to support new research information services for active researchers and the advancement of collaborative research. This study has its limitation for interpreting the diverse academic fields of the social sciences in a uniform way. In future study, it is necessary to conduct studies using various weighted indices for network centrality in order to measure the influence of research.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.394-396
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• 2006

When developing a new GPS receiver module, the essential problems are evaluation of reliable algorithms, software debugging, and performance comparison between algorithms to find optimal solution. Most GPS receiver modules nowadays use a correlator to track signals from satellites and an MCU (Micro Controller Unit) to control operations of the entire module. The problem of software evaluation from MCU is very difficult, due to limitation of MCU resources and low ability of interfacing with user. Normally, user has to expense special tool kit for a limiting access to MCU but it is also hard to use. This article introduces an implementation of a GPS receiver test bed using correlator GP2021 interfacing with ISA (Industry Standard Architecture) PC bus. This way can give user complete control and visibility into the operation of the receiver, then user can easily debug program and test algorithms. For this article, the least square method is implemented to test the hardware and software performance.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제16권7호
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• pp.789-793
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• 2010

최근 플래시 메모리 기반 비휘발성 캐시가 저장장치의 성능과 전력 소모 측면에서 효과적인 해법으로 떠오르고 있다. 비휘발성 캐시로 저장장치의 성능을 향상시키고 전력 소모를 줄이기 위해, 가격이 싸고 용량이 큰 multi-level-cell (MLC) 플래시 메모리를 사용하는 것이 좋다. 그러나 MLC 플래시 메모리의 수명은 single-level-cell (SLC) 플래시 메모리보다 훨씬 짧기 때문에 전체 저장장치의 수명이 짧아질 수 있다. 이러한 약점을 최소화하기 위해 SLC 플래시 메모리와 MLC플래시 메모리를 결합한 형태의 비휘발성 캐시를 고려해볼 수 있다. 본 논문에서는 SLC와 MLC를 결합한 플래시 메모리를 버퍼로 사용하는 새로운 하이브리드 하드디스크 구조를 제안한다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제16권4호
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• pp.437-441
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• 2010

무선 센서 네트워크가 적용되는 새로운 응용분야는 점점 더 정교하고 복잡한 태스크 수행과 정해진 시간내에 태스크 수행을 완료해야 한다는 조건 만족을 요구하고 있다. 그러나 현재까지, 무선 센서 네트워크에서 센서 노드의 자원 제약성과 수행 작업 특성을 고려한 실시간 센서 운영체제 기반의 인터럽트 처리 기법에 관한 연구는 미비하다. 본 논문에서는 센서 운영체제에서 실시간성을 만족시키기 위한 요구 사항들을 분석하고, 이를 바탕으로 시스템을 설계 및 구현한다. 또한 다양한 검증을 통해, 제안하는 기법의 신뢰성 제공을 확인하며, 시뮬레이션을 통해 실시간 특성에 대한 요구사항 충족 및 성능의 효율성을 검증한다.