• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.91-94
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• 2007

본 논문에서는 $90^{\circ}$ hybrid branch-line coupler와 three-arm branch $90^{\circ}$ hybrid coupler를 이용하여 설계한 six-port 위상 상관기를 ADS2003A을 사용하여 모의 실험하고 성능을 분석하였다. Three-arm branch $90^{\circ}$ hybrid coupler를 이용한 six-port 위상 상관기가 기존의 $90^{\circ}$ hybrid coupler를 이용한 six-port 위상 상관기보다 약 5배정도의 광대역 특성을 보였다. 두 개의 six-port 위상 상관기의 성능을 비교 검증하기 위하여 six-port 위상 상관기를 제작 평가하였다 측정된 두 개의 six-port 위상 상관기의 특성은 시뮬레이션 데이터와 거의 일치하였다.

• 한국정보통신학회논문지
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• 제12권3호
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• pp.414-419
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• 2008

Six-port 위상 상관기는 한 개의 power divider 와 세 개의 hybrid coupler로 구성되어 진다. 본 논문에서는 광대역 특성을 갖는 three-arm branch $90^{\circ}$ hybrid coupler를 사용한 six-port 위상 상관기를 ADS2003A을 사용하여 중심 주파수 11.85 GHz에서 설계하여 시뮬레이션을 통해 성능을 분석하였다. 모의 실험결과 three-arm branch $90^{\circ}$ hybrid coupler를 이용한 six-port 위상 상관기의 대역폭은 약 1.5GHz$(10.8{\sim}12.3)$로 기존의 $90^{\circ}$ hybrid branch-line coupler를 이용한 six-port 위상 상관기보다 약 5배 정도의 광대역 특성을 보였다. Six-port 위상 상관기의 port간 위상 오차는 $5^{\circ}$ 이하로 양호한 특성을 보였으며, 모의 실험한 결과를 바탕으로 six-port 위상 상관기의 실질적인 성능을 비교 검증하기 위하여 six-port 위상 상관기를 제작하고 성능을 측정하였다. 측정된 six-port 위상 상관기의 특성은 시뮬레이션 데이터와 거의 일치하였다.

• 전력전자학회논문지
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• 제23권5호
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• pp.366-372
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• 2018

Three-port dual-active bridge (DAB) converter in a DC microgrid was studied due to its high power density and cost-effectiveness. The other advantages of DAB include galvanic isolation and bidirectional power conversion capability using simple control modulation. The three-port DAB converter consists of a three winding transformer and three bridges. The transformer has three phases, which means that the ports are coupled. Thus, the three-port DAB converter causes unwanted power flows when the load connected to each port changes. The basic operational principles of the three-port DAB converter are presented in this study. The decoupling control strategy of the independent port power transfer is presented with a mathematical power model to overcome the unexpected power flow problem. The validity of the proposed analysis and control strategy is verified with PSIM simulation and experiments using a 1-kW prototype power converter.

• Journal of Chest Surgery
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• 제47권4호
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• pp.384-388
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• 2014

Background: Recently, single-port video-assisted thoracic surgery (VATS) has been proposed as an alternative to the conventional three-port VATS for primary spontaneous pneumothorax (PSP). The aim of this study is to evaluate the early outcomes of the single-port VATS for PSP. Methods: VATS was performed for PSP in 52 patients from March 2012 to March 2013. We reviewed the medical records of these 52 patients, retrospectively. Nineteen patients underwent the conventional three-port VATS (three-port group) and 33 patients underwent the single-port VATS (single-port group). Both groups were compared according to the operation time, number of wedge resections, amount of chest tube drainage during the first 24 hours after surgery, length of chest tube drainage, length of hospital stay, postoperative pain score, and postoperative paresthesia. Results: There was no difference in patient characteristics between the two groups. There was no difference in the number of wedge resections, operation time, or amount of drainage between the two groups. The mean lengths of chest tube drainage and hospital stay were shorter in the single-port group than in the three-port group. Further, there was less postoperative pain and paresthesia in the single-port group than in the three-port group. These differences were statistically significant. The mean size of the surgical wound was 2.10 cm (range, 1.6 to 3.0 cm) in the single-port group. Conclusion: Single-port VATS for PSP had many advantages in terms of the lengths of chest tube drainage and hospital stay, postoperative pain, and paresthesia. Single-port VATS is a feasible technique for PSP as an alternative to the conventional three-port VATS in well-selected patients.

• 한국항만경제학회:학술대회논문집
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• 한국항만경제학회 2007년도 정책세미나 및 국제학술대회
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• pp.441-455
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• 2007

Based on the fact that Qingdao port, Tianjin port and Dalian port of the economic circle around Bohai have been the three islands of stability through long-term competition, this paper conducts a system study on the competitive powers of the three ports through AHP model on the analysis of current status of the three ports, and probes deeply into the outer factors and the inner factors affecting on the competitive advantage, and points out the existing problems in competition. We think that the three ports must compete orderly and collaborate closely, and give the forms and approaches developing strategy collaboration in order to obtain an advantageous position in Northeast Asia and improve the international competitive power.

• Journal of Power Electronics
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• 제17권6호
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• pp.1433-1444
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• 2017

A family of non-isolated DC-DC three-port converters (TPCs) that allows for a more flexible power flow among a renewable energy source, an energy storage device and a current-reversible DC bus is introduced. Most of the reported non-isolated topologies in this area consider only a power consuming load. However, for applications such as hybrid-electric vehicle braking systems and DC microgrids, the load power generating capability should also be considered. The proposed three-port family consists of one unidirectional port and two bi-directional ports. Hence, they are well-suited for photovoltaic (PV)-battery-DC bus systems from the power flow viewpoint. Three-port converters are derived by combining different commonly known power converters in an integrated manner while considering the voltage polarity, voltage levels among the ports and the overall voltage conversion ratio. The derived converter topologies are able to allow for seven different modes of operation among the sources and load. A three-port converter which integrates a boost converter with a buck converter is used as a design example. Extensions of these topologies by combining the soft-switching technique with the proposed design example are also presented. Experiment results are given to verify the proposed three-port converter family and its analysis.

• 한국항만경제학회지
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• 제23권4호
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• pp.1-22
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• 2007

본 논문은 인천항과 청도항, 천진항, 대련항을 대상으로 항만별 서비스품질 구성요인들 각각이 고객만족에 미치는 영향정도가 어떻게 다른지와 항만별 서비스품질의 각 차원 및 만족도에 대한 고객의 지각 수준을 비교하였다. 연구결과 항만서비스의 품질차원은 '내적품질', '외적환경품질', '상호작용품질'로 구분됨을 확인하였고, 대련항의 '외적환경품질'을 제외하곤 항만의 서비스품질 3차원 모두가 고객만족에 유의한 영향을 미치는 것으로 나타났다. 또한 항만간 서비스품질 각 차원에 대한 고객의 지각 수준을 그룹비교를 통해 살펴 본 결과 인천항은 '내적품질'에서 청도항, 천진항, 대련항에 비해 낮게 평가되었으며, '외적환경품질'의 경우도 청도항, 천진항에 비해 낮았지만, '상호작용품질'은 천진항과 대련항에 비해 높게 평가되었다. 그러나 항만에 대한 고객의 만족은 인천항이 청도항, 천진항에 비해 부족한 것으로 나타났다.

• 한국전자파학회지:전자파기술
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• 제5권2호
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• pp.39-45
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• 1994

본 논문에서는 3선 마이크로스트리으로 구성된 3선 3포트 대역통과/대역소거 필터를 해석하는 방법과 설계 예를 제시하였다. 실제로 제작한 대역통과/대역소거 필터의 측정 결과는 이론적인 특성과 잘 일치함을 보였다.

• Journal of Power Electronics
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• 제19권5호
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• pp.1278-1288
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• 2019

A DC-DC Non-Isolated Three-Port Cuk-Cuk (NI-TPCC) converter for interfacing renewable energy sources (RESs) such as Fuel Cell (FC) and Photovoltaic (PV) energy with a DC load is presented in this paper. It features single-stage power conversion from both of the input ports to the load port. The proposed NI-TPCC converter is designed based on the classical Cuk converter. The operational modes and power flow are analyzed in the continuous conduction mode (CCM), and the relationships among the port voltages are derived. Continuous currents in all three ports with less ripple enhance the performance of a fuel cell and its operating life. Furthermore, the output inductor is shared with both of the input ports, which reduces the number of active and passive components. The effectiveness of the designed NI-TPCC converter has been validated through simulation and experimental results.

• Journal of Power Electronics
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• 제18권5호
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• pp.1293-1302
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• 2018

Multiport power converters have recently become popular to researchers and engineers. However, more improvements are required in terms of their soft-switching operation, bidirectional operation, and integration. In this study, a bidirectional three-port three-switch DC-DC converter is proposed. The converter contains a low-current ripple port and ripple-free current port. Through the integrated structure, utilization of a coupled inductor, and a new switching strategy, the aforementioned specifications are achieved. A modified switching strategy is also utilized in the converter, which has resulted in the bidirectional operation of the converter between ports. Finally, a comprehensive analysis is presented, and the converter characteristics are validated by experimental results.