• Journal of Korean Society of Steel Construction
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• v.27 no.1
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• pp.77-85
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• 2015

This paper describes the development of force limiting device(FLD). The FLD could induce compressive yield before occurring elastic buckling for slender member under compressive load. Therefore, it might prevent reduction of load carrying capacity by elastic buckling and the structures with the devices would behave stable. A new type of FLD reduced cross area is proposed in this study different to existing studies like as out of plane type, slit type and folded plate type. The parameters of specimens are depth, width and number of cutting. The structural capacity and characteristics of proposed types were verified by experiment and FEM analysis. The FLD of cutting type is efficient in compressive member.

• Journal of IKEEE
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• v.13 no.3
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• pp.7-17
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• 2009

WiMedia UWB technology is a fully distributed data communication technology developed for the application demanding a high data transmission rate in the wireless PAN area. In general, devices can send data either by reserving time slots or by using prioritized CSMA/CA. If the PCA protocol of prioritized CSMA/CA is used, they are suffered congestion as the number of devices increases. In this paper, we propose a Deterministic Access Protocol(DAP) in WiMedia WPANs. A DAP is a method to transmit data in the non-reserved DRP period without competition as each device informs the beacon order information in the beacon period and the queue information. In addition, the problem that the devices with a lower beacon slot number have more transmission opportunities is addressed by introducing the reference point. Simulation results are given to demonstrate that a DAP can improve the throughput and reduce the packet loss rate.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.707-708
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• 2008

본 논문에서는 초전도 플라이휠 에너지 저장장치 (Superconductor Flywheel Energy Storage System : SFES)의 에너지 변환을 위해 사용된 영구 자석형 전동 발전기(Permanent Magnet Synchronous Motor/Generator : PMSM/G)가 SFES의 에너지 저장효율에 미치는 영향을 평가하였다. SFES 시스템은 YBCO 벌크 초전도체를 이용한 저어널 타입(journal type)의 초전도 베어링을 사용하였으며, 슬롯리스 형 PMSM/G를 사용하였다. PMSM/G의 고정자 코어, 누설 자속 및 감겨진 코일에 의한 저장 에너지 손실을 측정하였다. 사용된 코어의 크기, 누설자속, 및 코일의 적절한 선정을 통하여 저장된 에너지의 손실을 상당히 줄일 수 있음을 확인하였다. 또한 영구자석과 코어가 동시에 회전하는 회전 코어형 전동발전기를 적용하여 에너지 손실을 매우 감소시킬 수 있음을 확인하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.57-62
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• 2017

Recently, the use of electronic control units in vehicle has increased. The ECUs are connected to in vehicle networks to process a large amount of information. In this paper, for an actuator that is interconnected to CAN and FlexRay, a FlexRay-CAN gateway is presented and a data packing algorithm with a bisection method of a FlexRay slot is proposed. And, a network based actuator control system and packing map is implemented. With the proposed packing method, contact force sensor data are transferred within the maximum allowed delay to ensure the stability. The proposed method is useful for control of distributed system.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.3
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• pp.256-261
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• 2013

The AIS(Automatic Identification System) has been widely used for ship safety at sea over the last 10 years. The AIS traffic load at VDL(VHF Data Link) has been continuously increased. As the traffic load at VDL increases, the quality of AIS service may be deteriorated. In the previous research, the AIS traffic has been analyzed in the major ports of Korea, and its problem due to traffic overload has been suggested. However, no solutions has been given so far. In this paper, the method of autimatically controlling the VDL traffic at AIS base station is represented.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.2 s.7
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• pp.23-31
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• 2005

ITS(Intelligent Transportation System) implementing information collection services and information support services for cars of moving fast needs a communication system of special aim such as RF-DSRC(Radio Frequency Dedicated Short Range Communication). Before RSE(Road Side Equipment) and OBE(On-Board Equipment) will be able to communicate RF-DSRC, OBE first have to request Link Initialization Access using ACTC(Activation Channel) in allocated ACTS(Activation Slot) by Slotted ALOHA. Even though Link Initialization Access is a important element to decide performance of communication system, optimal mathematic modeling study of Link Initialization Access which is adapted RF-DSRC characteristics is not enoush. So, in this paper, we propose mathematical modeling about Link Initialization Access of RF-DSRC. And then we computed Link Initialization Access probability defining offer load(G) which is adapted RF-DSRC characteristics for analyzing performance of modeling.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.4
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• pp.69-76
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• 2005

In this paper, a 2 stage 6-pole bandpass filter(BPF) is designed and implemented by using triple-mode cavity for satellite payload system. The BPF has a 100MHz bandwidth at the center frequency of 14.5GHz(Ku-band) and the response of the filter is the Chebyshev function. The cavity filter uses two orthogonal $TM_{113}$ modes and one $TM_{012}$ mode. The coupling between the adjacent cavityes(intercavity coupling) results in a Chebyshev response and is accomplished by only H-filed component of If modes. The size and location of intercavity slot is determined by the coupling equation from E-and H-field of TE and TM resonant modes in circular cavity. The 2-stage 6-pole triple-mode cavity BPF has the insertion loss of 2.4dB and the reflection loss of 15dB in the passband. The triple-mode BPF proposed in this thesis can be used as channel filters for satellite payload system and can minimize filter assembly in general wireless communication system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2263-2268
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• 2015

This paper describes packet scheduling techniques that can be used to alleviate the impact of interference. The mechanism is consisted of interference estimation and master delay police. Proposed scheduling police is effective in reducing packet loss and delay. Another advantage worth mentioning, are the additional saving s in the transmitter power since packet are not transmitted when channel is bad. This paper gives that scheduling policy works only with data traffic since voice packets need to be sent at fixed intervals. However, if the delay variance is constant and the delay can be limited to a slot, it may be worthwhile to use DM packet for voice.

• Tunnel and Underground Space
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• v.5 no.4
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• pp.323-335
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• 1995

지열에너지 개발의 기본적 개념은 지하 심부의 고온건조암체에 시추공을 이용한 수압파쇄를 실시하여 고온건조암체내에 인공파쇄대를 형성함으로써 유체의 유동회로를 구축하여 지열에너지의 회수를 도모하는 것이다. 본 논문에서는 수압파쇄균열의 발전방향 조절문제와 관련하여, 초고압수 절삭장치를 이용, 수압파쇄공 내에 인공슬롯을 형성하여 수압파쇄를 실시함으로써 균열의 발전방향을 조사하였으며, 수압파쇄에 의한 파쇄대내로의 유체순환실험을 통해 지열수의 유동특성을 규명하였다. 이를 위해 모델에 종균열과 횡균열을 형성시키고 균열내에 주입되는 물의 주입률, 정상류압력, 흐름저항을 조사하고, 이 결과를 이용하여 전산모델링을 수행하였다. 인공절리면에 대한 투수시험에서는 10$0^{\circ}C$까지의 온도변화에 따라 투수계수가 증가하였으며, 봉압 증가에 따라 증가율이 현저히 감소하였다.

• The korean journal of orthodontics
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• v.37 no.5
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• pp.376-385
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• 2007

Esthetic brackets which resemble the color of natural teeth have been widely used. But the frictional resistance of ceramic brackets, a typical esthetic bracket, is greater than that of metal brackets. The purpose of this study was to measure the frictional resistance of the new calcium phosphate brackets (CPB) which were recently developed and to evaluate its clinical usability by comparing the frictional differences of CPB with metal brackets and metal slot inserted ceramic brackets. Methods: Experimental groups were CPB (Hyaline II, Tomy, Tokyo, Japan), metal bracket (Kosaka, Tomy, Tokyo, Japan) and metal slot inserted ceramic bracket (Clarity, 3M Unitek, Monrovia, CA, USA). All of the brackets had 0.022-inch slot sizes. The brackets were tested with $0.019\;{\times}\;0.025$ inch stainless steel wire (3M Unitek, Monrovia, CA, USA). A biologic model was used to simulate the situation which would occur during orthodontic treatment with fixed appliances. Retraction force was applied at a speed of 5 mm/min for 30 seconds. The frictional resistance was measured on a universal testing machine (Instron 4467, Instron, Norwood, MA, USA). Results: CPB showed significantly higher friction than metal brackets (p < 0.05) and lower friction than metal slot inserted ceramic brackets (p < 0.01). Conclusions: CPB can be considered to be a useful orthodontic esthetic bracket with respect to frictional resistance, as its friction is remarkably lower than that of metal slot inserted ceramic brackets.