• Journal of the korean Society of Automotive Engineers
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• v.15 no.1
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• pp.55-66
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• 1993

The characteristics of the flow processes in the cylinder of the two-stroke cycle engines have become the subject of increasing and attention owing to the simplicity and the higher power per unit weight of the two-stroke cycle engine. Among the many factors which influence on the scavenging flow, the port angle is important factor. Hence, four different type models with one inlet-port and two side-ports are studied to show the effect of port angle on the laminar scavenging flow. When the inlet-port axial is relatively larger than the side-port axial angle, it is showed that the fresh charge penetrate into the burned gas and displace it first toward the cylinder head and then toward the exhaust port. When the inlet-port axial angle is much less than the side-port axial angle, the fresh charge through the inlet-port directly move toward the exhaust port. The result showed that the model A may suppress the generation of vortices in the vicinity of inlet and side prots which restrict the sufficient supply of fresh charge and obstruct the perfect displacement of all combustion products.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.3
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• pp.259-269
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• 2020

With the proposal-agreement procedure, RSTP can reduce the network recovery time to 400 ms or less in the case of 40 bridges. While the legacy RSTP reverts the previous agreement at the bridge with the alternate port role in the ring during the fault recovery, a new position based fast fault recovery procedure is proposed in this paper to guarantee a single proposal-agreement transaction which can provide more faster recovery. By knowing the relative position of the faulty link or bridge in hops, the bridge on the middle of the ring can complete the recovery procedure without revert. The performance of proposed procedure is numerically calculated and verified by simulation and the result shows that the recovery time can be reduced up to 100 ms, which is 1/4 times of the legacy RSTP.

• Journal of Veterinary Clinics
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• v.32 no.1
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• pp.9-15
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• 2015

Purpose of this study is to determine the reasonable portal approach for thoracoscopic right middle lung lobectomy in small sized dogs under 10 kg. Ten healthy beagle dogs weighing $8.67{\pm}0.49kg$ were included. Under general anesthesia, one-lung ventilation (1LV) was achieved using endobronchial blocker with guidance of fiber-optic bronchoscope. Two portal approaches were used; 8-6-10 intercostal space (ICS) and 8-6-5 ICS approach. Thoracoscopic right middle lung lobectomy was performed using endoscopic linear self-cutting stapler and specimen retrieval bag. Each approach was evaluated by scoring 0; bad, 1; endurable, 2; good, 3; excellent in following five category, 1) visualization, 2) triangulation; instrumental sword fighting in the thoracic cavity, 3) approach to hilar pedicle; application of stapler, 4) any obstacles in applicating Lap Bag, and 5) the operator's convenience. Favorable working space was secured by 1LV and thoracoscopic right middle lung lobectomy was successfully completed in all dogs. There was no need to change the portal location and iatrogenic complication. Most of scores were good to excellent in both approaches. Consequently, both approaches are feasible methods for thoracoscopic right middle lung lobectomy with one lung ventilation using endoscopic linear self-cutting stapler in dogs weighing less than 10 kg.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1095-1101
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• 2012

This paper presents a design of a BLDC servo motor control system for the auto process of assembly and supply using DSP(Digital Signal Processor) controller and IGBT driver. The assembly and supply auto processing system needs torque, speed, position control of servo motor for variable action. This paper implements those servo control with vector control and space vector PWM(Pulse Width Modulation) technique. As CPU of controller, TMS320F240 DSP was adopted because it has PWM waveform generator, A/D converter, SPI(Serial Peripheral Interface) port and many input/output port etc. This control system consists of 3-level hierarchy structure that main host PC manages three sub DSP system which transfer downward command and are monitoring the states of end servo controllers. Each sub DSP system operates eight BLDC servo controllers which control BLDC motor using DSP and IPM. Between host system and sub DSP communicate with RS-422, between main processor and controller communicate with SPI port.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.589-591
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• 2004

VLSI 설계 생산성의 향상을 위하여 여러 대학 및 연구소, 기업체들은 다양한 종류의 CAD 툴을 사용하고 있다 각 단체에서 CAD 툴을 사용하기 위해서는 CAD 툴을 설치한 후. 사용자가 직접 라이센스 파일의 위치를 환경변수에 설정하거나, 라이센스 서비스 데몬이 실행되어 있는 컴퓨터의 포트번호와 서버의 이름을 관리자에게 요청하여 환경변수를 직접 설정해주어야 하는 번거로움이 발생한다. 또한, 라이센스의 관리 및 어떤 CAD 툴이 사용 가능한지 확인이 어렵다 본 논문에서는 네트워크 상의 라이센스 서버로부터 vlf요한 라이센스 정보를 찾고, 환경변수를 설정하는 라이센스 처리과정을 보다 효율적으로 하기 위해, 네트워크 상의 서비스 발견과 이용을 쉴게 해주는 Jini를 사용하여 라이센스를 공유하는 방식을 제안한다.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.3
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• pp.65-72
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• 2019

HPC(High Performance Computing) is the computing system that connects a number of computing nodes with high performance interconnect network. In the HPC, interconnect network technology is one of the key player to make high performance systems, and mainly, Infiniband or Ethernet are used for interconnect network technology. Nowadays, PCIe interface is main interface within computer system in that host CPU connects high performance peripheral devices through PCIe bridge interface. For connecting between two computing nodes, PCIe Non-Transparent Bridge(NTB) standard can be used, however it basically connects only two hosts with its original standards. To give cost-effective interconnect network interface with PCIe technology, we develop a prototype of interconnect network system with PCIe NTB. In the prototyped system, computing nodes are connected to each other via PCIe NTB interface constructing switchless interconnect network such as ring network. Also, we have implemented prototyped data sharing mechanism on the prototyped interconnect network system. The designed PCIe NTB-based interconnect network system is cost-effective as well as it provides competitive data transferring bandwidth within the interconnect network.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1681-1693
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• 1997

In a distributed system, the simple file allocation problem determines the placement of copies of a file, so as to minimize the operating costs. The simple file allocation problem assumes the cost parameters to be fixed. In practice, these parameters change over time. In this research, dynamic file allocation problem for both single and multiple files are considered, which account for these changing parameters. A model for dynamic file allocation problem is formulated as a mixed integer program for which Lagrangian relaxation based branch-and-bound algorithm is developed. This algorithms is implemented and its efficiency is tested on medium to large test problems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.125-135
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• 2001

A 8$\times$4 microstrip antenna array is designed at 5.3 GHz and its characteristics are investigated with respect to the application in dual polarized synthetic aperture radars. The design is focused on the achievement of a wide bandwidth, a high polarization purity, a low loss, a good isolation and some mechanical requirements suitable for the application. The antenna is fed by a -3 dB tapered feed network, and is composed of dual polarized SSFIP (Strip-Slot-Foam-Inverted Patch) elements with honeycomb and shielding plane. Simulation results for the antenna array are presented and compared with measurements. It is observed that the antenna shows a bandwidth of 80 MHz, a polarization isolation better than 20 dB, an isolation of 40 dB, and good mechanical characteristics.

• Journal of The Korean Association For Science Education
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• v.38 no.3
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• pp.319-329
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• 2018

Research Projects allow students to experience of scientific research by conducting experiments on specific scientific subjects and writing reports. The process of research begins as students find and propose research questions and its importance has been consistently emphasized. In this study, we developed various strategies to support students to draw research questions and applied to each phase. We analyzed how students' research questions were developed at different phases. The program consists of five phases, such as (1) Exploration, (2) Literature Review and Data Collection, (3) Modification and Extension, (4) Sharing and Evaluation, (5) Final Selection and Research Plan. The program was applied to high school Research Project for 12 hours. A total of 13 students were divided into four groups of 3-4 students and conducted researches. The results of each student's research process and final research plans were then collected and analyzed. The overall quality of research questions produced by the students showed improvement in each phase. Each strategy improved in various aspects of the research questions at each level. Students were able to find their own area of interest in the 'Exploration' phase and then they began to suggest verifiable plans in the 'Literature and Data Collection' phase. They were able to find a variety of variables under the 'Modification and Extension' phase, whereas the precision of research questions improved in the 'Sharing and Evaluation' and the 'Final Selection and Research Plan' phase.

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.51-56
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• 2014

High-availability seamless redundancy (HSR) is a protocol for fault-tolerant Ethernet (FTE) networks. It provides two frame copies and each copy is forwarded on a separate physical path, which provides zero fail-over time. Therefore, the HSR is becoming a potential candidate for various real-time FTE applications. However, the generation and circulation of unnecessary frames due to the duplication of every sending frame is inherent drawback of HSR. Such drawback degrades the performance of the network and may deplete its resources. In this paper, we present a new algorithm called port locking (PL) based on the media access control (MAC) address to solve the abovementioned problem in popular connected-rings network. Our approach makes the network gradually learn the locations of the source and the destination nodes without relying on network control frames. It then prunes all the rings that do not contain the destination node by locking corresponding rings' entrance ports. With the PL algorithm, the traffic can be significantly reduced and therefore the network performance will be greatly enhanced specially in a large scale connected-rings network. Analytical results are provided to validate the PL algorithm.