• 대한전자공학회논문지
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• 제21권4호
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• pp.24-30
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• 1984

군지연왜곡(상위왜곡)은 음성전송의 입장에서는 그다지 문제가 되지 않는 특성이다. 그러나 기존의 공중교환전화망(음성대역전송)을 통하여 데이터, FAX 등의 파형전송을 하는 경우에는 데이터 신호를 왜곡시키는 최대의 요인이 되므로 이를 철저하게 검토하여야 한다. 본고는 기존의 공중교환전화망을 데이터전송에 개방하기 위하여 군지연왜곡에 관한 해석을 하고, 실험 및 측정결과를 기술하고 또 이 왜곡의 개선에 대해서도 언급한 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 심포지엄 논문집 정보 및 제어부문
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• pp.65-67
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• 2004

Change of state of Channel between two wireless terminals which is caused by noise and multiple environmental conditions for happens frequently from the Wireles Network. So, When it is like that planning a wireless network protocol or performance analysis, it follows to change of state of time-varying channel and packet the analysis against a transmission efficiency is necessary. In this paper, analyzes transmission time of a packet and a packet in a time-varying and packet based Wireless Network. To reflecte the feature of the time-varying channel, we use a Signal Flow Graph model. From the model the mean of transmission time and the mean of queue length of the packet are analyzed in terms of the packet distribution function, the packet transmission service time, and the PER of the time-varying channel.

• 한국통신학회논문지
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• 제37B권9호
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• pp.734-740
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• 2012

본 논문에서는 인트라세션 네트워크 코딩을 사용하여 멀티레이트 멀티홉 무선 네트워크의 처리율을 향상하기 위한 방법을 제안한다. 멀티레이트는 다양한 전송 속도를 사용하여 전송 속도와 전송 반경에 대하여 다양한 타협점을 가질 수 있어 환경 변화에 따른 성능 변화에 대처할 수 있다. 이러한 멀티레이트 환경에서 인트라세션 네트워크 코딩을 사용할 경우 새로운 전송 속도를 결정하는 방법을 제안한다. 멀티레이트를 사용하는 각 노드에서 인트라세션 네트워크 코딩을 사용하여 유효 전송 속도를 계산하고 가장 높은 유효 전송 속도를 갖는 전송 속도를 선택한다. 선택된 전송 속도를 사용하여 동시 전송 집합을 결정하고 선형계획법을 적용하여 멀티홉 무선 네트워크의 처리율을 계산한다. MATLAB과 lp_solve IDE 프로그램을 이용하여 두 가지 토폴로지에서 성능 평가를 수행하였으며, 제안한 방식의 처리율이 향상되었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.484-489
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• 2002

Whenever the accidents occur in the railway areas, their prompt recovery is very important. The individual way has been used to resolve these accidents by direct visiting the site and reporting to others who cares for these cases. As a result, we are planning to operate the MTS (Moving picture Transmission System) for a timely information's transmission to the related peoples in the central control center by transforming the picture information on the accident-site to the digital information. The proposed system is not a transmission system using exclusive lines, but utilizing the existing railway computer network. We construct a network server device so that a dispatcher can easily connect with the server through the railway intranet. In some railway environments such as disturbed field situations and geographical condition(in tunnels and bridges, etc) building up the wired network is difficult. Solving this problem, we reviewed the wireless network. Finally we proposed the mixed wireless network that is able to cover the wired network. We then installed and tested the wired network and wireless network respectively in wayside of a railway field. Through the testing, we identified many detailed matters for some network construction approaches to the control room and many field device-connecting schemes. This research will contribute to minimize the number of staff dispatched to a disturbed field, decrease the accident recovery time and improve the quality of service to the passenger.

• 조명전기설비학회논문지
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• 제25권2호
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• pp.87-95
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• 2011

A Renewable Portfolio Standard(RPS) is a regulation that requires the increased generation of energy from renewable energy sources such as solar, wind, fuel cell, small hydro, biomass and geothermal. By environmental, technical and these regulatory reasons, the amount of renewable energy sources will be increased in a network. However, it is hard to assess risk of a transmission network with large scale renewable energy sources because the output characteristics of renewable energies are intermittent. This paper evaluates effects of a transmission system with supplemental large scale renewable energies into the existing system. To evaluate these effects, a methodology for risk level of components in a network is proposed considering steady state and contingency N-1 in this paper. We consider line current and bus voltage in each state of a network.

• 전기학회논문지
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• 제64권1호
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• pp.23-28
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• 2015

Two old synchronous condensers in Jeju are being replaced by new machines to operate Jeju AC network with Haenam-Jeju HVDC system stably. Before new synchronous condensers operate on site, voltage stability analysis is conducted to verify stable operation of jeju AC network. Through impedance analysis of the synchronous machine, transformer and ac network, the equivalent circuit is constructed and the voltage drop during start-up is calculated. Then, PSS/E fault analysis is performed to acquire short-circuit capacity according to the generator operation scenarios. Voltage variation when starting synchronous condenser is simulated in PSCAD/EMTDC and satisfies the operating condition of jeju AC network and HVDC #1 system.

• Journal of Mechanical Science and Technology
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• 제19권10호
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• pp.1875-1884
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• 2005

This paper discusses Neural Networks as predictor for analyzing of transmission angle of slider-crank mechanism. There are different types of neural network algorithms obtained by using chain rules. The neural network is a feedforward neural network. On the other hand, the slider-crank mechanism is a modified mechanism by using an additional link between connecting rod and crank pin. Through extensive simulations, these neural network models are shown to be effective for prediction and analyzing of a modified slider-crank mechanism's transmission angle.

• 전기학회논문지
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• 제63권6호
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• pp.752-757
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• 2014

This paper attempts to evaluate the impact of power plant penetration on constraints of a transmission network and proposes a methodology based on risk level, which can evaluate the condition of the network and facilities intuitionally. Furthermore, based on this methodology, RLII(Risk Level Improvement Index) is proposed in order to establish comprehensive TNEP(Transmission Network Expansion Planning) from a viewpoint of ISO(Independent System Operator). In order to verify the proposed methods in this paper, real power systems in Incheon and Shiheung areas, south Korea are applied to the case study.

• 한국통신학회논문지
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• 제40권10호
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• pp.1931-1933
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• 2015

본 논문은 이종 네트워크 환경에서 무선 통신 시스템의 신뢰성 향상을 위한 인접 셀 간 협력 전송 기법을 제안한다. 이종 네트워크는 현존하는 기술을 사용하여 데이터 전송 속도를 높일 수 있다는 장점이 있다. 하지만 셀 가장자리에서의 통신 성능 저하 현상이 심각한 문제로 대두되고 있다. 따라서 본 논문은 문제 해결을 위해 상황에 따라 적응적으로 전송하는 인접 셀 간 협력 전송 기법을 제시한다.

• International Journal of Computer Science & Network Security
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• 제22권4호
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• pp.223-228
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• 2022

Femtocells are being incorporated into heterogeneous networks in order to increase the network capacity. However, intensive deployment of femtocells results in undesired interference, which lowers the system's performance. Controlling the femtocell transmission power is one of of the aspects that can be addressed in order to mitigate the negative effects of the interference. It may also be utilized to facilitate the auto-configuration of the network's conductance, if necessary. This paper proposes the use of an auto-configuration technique for transmission power. The suggested technique is based on the transmission power of macrocells and the coverage provided by femtocells. The simulation findings show that the network's capacity has increased, and the amount of interference has decreased.