• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.240-241
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• 2004

JP Nagoya. Inc started special work(passenger order} to transmit information to the passenger from 2001 following the eastern area' heavy rain in 2000. They introduced 'Passenger Information System' which uses self communication network(LAN, PHS) mainly and wire/wireless and internet jointly. As an information transmission method of this system, there is "train information transmission using PHS" which transmits info to LED display in special train. This system configured by adding new equipments and using existing equipments, network in maximum, this study reviewed the system, which transmits real time operation condition unified by these passenger order to passenger in high quality, more promptly.

• E2M - 전기 전자와 첨단 소재
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• 제9권3호
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• pp.246-250
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• 1996

In optical soliton transmission systems with nonlinear dispersive materials, which is utilized for ultra-long and high bit rate transmission, it is shown that the value of initial time difference between adjacent solitons is analyzed for optimum bit rate. The method is inducted by uncorrelation condition with minimum interaction forces in initial covariance coefficient between adjacent solitons. When the initial time difference is 6 times of soliton pulse width by the results, it is shown that the reliability is maintained with more than 90% within transmission length of soliton period. multiplied by 93.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권6호
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• pp.2680-2696
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• 2018

The collaborative content caching system is an effective solution developed in recent years to reduce transmission delay and network traffic. In order to decrease the service end-to-end transmission delay for future 5G ultra-dense networks (UDN), this paper proposes a novel service migration method that can guarantee the continuity of service and simultaneously reduce the traffic flow in the network. In this paper, we propose a service migration optimization model that minimizes the cumulative transmission delay within the constraints of quality of service (QoS) guarantee and network condition. Subsequently, we propose an improved firefly algorithm to solve this optimization problem. Simulation results show that compared to traditional collaborative content caching schemes, the proposed algorithm can significantly decrease transmission delay and network traffic flow.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.318-330
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• 2015

In wearable sensor systems (WSSs), sensor nodes are deployed around human body parts such as the arms, the legs, the stomach, and the back. These sensors have limited lifetimes because they are battery-operated. Thus, transmission power control (TPC) is needed to save the energy of sensor nodes. The TPC should control the transmission power level (TPL) of sensor nodes based on current channel conditions. However, previous TPC algorithms did not precisely estimate the channel conditions. Therefore, we propose a new TPC algorithm that uses an accelerometer to directly measure the current channel condition. Based on the directly measured channel condition, the proposed algorithm adaptively adjusts the transmission interval of control packets for updating TPL. The proposed algorithm is efficient because the power consumption of the accelerometer is much lower than that of control packet transmissions. To evaluate the effectiveness of our approach, we implemented the proposed algorithm in real sensor devices and compared its performance against diverse TPC algorithms. Through the experimental results, we proved that the proposed TPC algorithm outperformed other TPC algorithms in all channel environments.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.1063-1066
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• 1996

On the prediction of driving performance, an acceleration performance is normally simulated in stall starting condition which is the engine status of full-throttle and high-speed. The lack of transient engine torque data makes the difficulty of predicting an acceleration performance on engine-idle start condition. A experimental equation of transient engine torque is derived from vehicle performance test data. It is applied to simulation the accleration performance prediction on idle starting condition.

• Tribology and Lubricants
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• 제12권3호
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• pp.107-114
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• 1996

MoS$_{2}$ bonded film was applied to reduction gears, and its lubricating properties were experimentally evaluated in terms of the power transmission efficiency and the frictional noise with a dynamo-typed gear test rig. Tests were performed in both oil lubrication and dry condition where the rotating velocity and loading torque were varied. In dry condition, MoS$_{2}$ bonded films effected the power transmission efficiency to increase about 5%, and the frictional noise level to decrease about 6 dB under the test operating conditions. It well proved that MoS$_{2}$ bonded films were a very effective solid lubricant for reduction gears. In oil lubricating conditions, the frictional properties of the coated gears were mainly governed by the lubricating oil, and lubricating effects of MoS2 bonded films were not evident. The result suggested that lubricating effect of MoS$_{2}$ bonded films would be limited to prevent a damage of reduction gears in the initial run when they were used in oil lubrication conditions.

• 전기학회논문지
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• 제67권3호
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• pp.352-357
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• 2018

In this paper, the improvement of the conductor temperature calculation algorithm is studied. The allowable current of the underground transmission line is determined by the conductor temperature limit. Usually to calculate the allowable current limit, the conductor temperature is assumed in the most worst environment condition. It is possible to increase the transmission capacity if the actual burial environment is considered. Therefore, in this paper an algorithm is proposed to calculate the conductor temperature by distinguishing two area of a underground transmission line condition - the manhole where the temperature sensor can be installed and the underground transmission line in which the temperature sensor can not be installed easily. When calculating the conductor temperature by the underground line in the pipeline, the existing standard describes each environment as a single soil heat resistance and one ambient temperature. In order to compensate this situation, thermal resistance model that can take into consideration the ground surface temperature and under ground temperature is proposed. It is shown that the accuracy of the proposed model is increased compared with the existing standard calculation result.

• 한국음향학회지
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• 제37권1호
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• pp.1-11
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• 2018

천해 환경에서 음파 전달은 경계면에 의해 구형 분산에서 원통형 분산으로 음파 전달 조건이 전환되는데, 이 지점을 음파 전달 조건의 변환점 (transition point)이라고 정의한다. 이론적으로 거리에 따른 전달손실을 이용하여 음파 전달 조건의 변환점을 계산할 수가 있으며, 본 논문에서는 포물선 방정식 기반 음향모델을 이용하여 Pekeris 도파관에서 송 수신기가 수층의 중심에 위치한 경우 전달손실을 모의한 후 변환점을 도출하였다. 계산된 변환점은 수층과 퇴적층의 음속비로 계산된 임계각으로 추정한 임계거리와 비교, 분석되었으며, 동일한 환경에서 수층에 음향채널이 존재하는 경우와 음원 수심 변화에 따른 변환점 변동성을 확인하였다. 최종적으로 2015년 5월, 제주도 서남쪽으로 약 65 km 떨어진 SAVEX15(Shallow Water Acoustic Variability EXperiment 2015) 실험에서 획득한 천해 환경에서의 거리에 따른 저 중주파수 음파 전달 실험의 전달손실 자료를 이용하여 실험 해역에서의 음파 전달 조건 변환점을 도출하였으며, 이를 실험해역의 해양환경과 비교를 통하여 음전달 특성을 파악하였다.

• 한국컴퓨터산업학회논문지
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• 제2권9호
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• pp.1147-1154
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• 2001

본 논문에서는 현재 운용되고 있는 NTSC TV송신시스템을 근거로 곧 설치되어 운용될 예정인 8-VSB DTV 전송시스템의 재원을 설계한다. 먼저 아날로그 NTSC와 디지털 8-VSB DTV의 지상파 방송의 경우 최적의 수신전계를 유지할 수 있는 조건을 검토한다. 또한 Longley-Rice의 전계강도 산출법을 이용해서 수신을 위한 최소한의 전계강도의 임계값을 산출한다. 8-VSB DTV전송은 NTSC 6MHz대역에서 HDTV가 가능하도록 19.39Mbps의 데이터를 고속으로 전송하는데 그 목표를 두고 있으므로, 무엇보다 송ㆍ수신점 사이의 전계강도의 최적화가 중요한 문제이다. 따라서 8-VSB DTV전송은 NTSC 서비스 커버리지에 비하여 확장되거나 효율적이어야만 한다. 끝으로 NTSC TV가 8-VSB DTV와 동일한 서비스 커버리지를 유지하기 위하여 NTSC VHF에서 DTV UHF로 전환 시 필요한 송신출력과 NTSC UHF에서 DTV UHF로의 전환 시 필요한 송신출력을 산출한다.

• 한국해안·해양공학회논문집
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• 제27권5호
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• pp.345-352
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• 2015

본 연구에서는 직립식 구조물의 전달파고계수 산정을 위한 2차원 수리실험을 실시하였다. 불규칙파를 입사파로 적용하였으며 직립식 구조물에 대한 전달파고계수 산정식을 제안하고, Goda(1969) 등의 결과와 비교하였다. Goda(1969)의 결과는 입사파로 규칙파를 적용한 결과로서 불규칙파를 적용한 본 실험의 결과와 차이를 보였다. Goda의 결과가 본 연구에 비하여 크게 전달파고계수를 제시하는 것을 알 수 있었다. 또한 Goda는 직립벽에 대하여 평균, 상한 및 하한에 대한 계수값을 제시하였으나(d=h조건), 본 연구에서는 각각의 설계요소(구조물 폭, 수심, 파장 등)가 전달파고계수에 주는 영향을 계수를 통하여 정량적으로 제시하였다. 또한 여유고가 0인 조건에 대한 에너지보존 및 전달파고 특성을 제시하였다.