• International journal of advanced smart convergence
• /
• 제12권4호
• /
• pp.55-62
• /
• 2023

Slotted-Aloha (S-Aloha) has been widely employed in random access networks owing to its simple implementation in a distributed manner. To enhance the throughput performance of the S-Aloha, connection-based slotted-Aloha (CS-Aloha) has been proposed in recent years. The fundamental principle of the CS-Aloha is to establish a connection with a short-sized request packet before transmitting data packets. Subsequently, the connected node transmits long-sized data packets in a batch of size M. This approach efficiently reduces collisions, resulting in improved throughput compared to the S-Aloha, particularly for a large M. In this paper, we address the short-term fairness of the CS-Aloha, as quantified by Jain's fairness index. Specifically, we evaluate how equitably the CS-Aloha allocatestime slots to all nodes in the network within a finite time interval. Through simulation studies, we identify the impact of system parameters on the short-term fairness of the CS-Aloha and propose an optimal transmission probability to support short-term fairness.

• 융합보안논문지
• /
• 제15권2호
• /
• pp.57-62
• /
• 2015

IP QoS는 인터넷 트래픽의 폭증을 수익으로 연결시키기 위해 기존의 Best Effort Service의 한계를 극복하는 것이 필수이다. 차세대 통신망의 필수요건으로 IP QoS는 매우 중요하다. 그러나, IP망은 QoS 보다는 유연성과 확장성에 초점을 맞추어 발전해왔다. 따라서, IP망에 QoS를 적용하기 위해 기존 IP 기술에 여러가지 품질확보를 위한 조치가 필요하다. 접속품질과 전송품질을 기반으로 한 IP QoS(Quality of Service) 품질 메트릭스를 정립 한다면 통신품질 저해요인을 분석하여 객관적인 자료를 얻을 수 있다. 통신품질 수준을 파악하면 품질 취약지역 및 품질 저해요인을 분석할 수 있다. 효율적인 품질 메트릭스 정립은 문제점에 대한 품질개선으로 통화품질 향상을 통한 고객 만족도를 증진효과를 기대할 수 있다.

• 대한전기학회논문지:전력기술부문A
• /
• 제51권2호
• /
• pp.102-108
• /
• 2002

This paper describes the overvoltage analysis and reduction methods of insulation joint boxes in underground transmission power cables when direct lightning surge strikes to overhead transmission line. An actual 154kV combined transmission line with underground Power cables was modelled in ATPDraw for simulation. Simulations were performed to analyze the overvoltage between insulation joint boxes, sheath-to-ground voltage according to the distance between cable conductors, cable lengths, burying types, CCPU connection types. The most effective method to reduce the induced overvoltage of Insulation joint boxes was proposed. It is evaluated that the proposed reduction method riven from the detailed simulations can be effectively applied to the actual underground power cable systems.

• 한국기계가공학회지
• /
• 제18권11호
• /
• pp.24-34
• /
• 2019

An automotive automatic transmission is a popular power-transmitting device in passenger vehicles, as it provides various speed ratios for diverse driving conditions with easy manipulation and smooth gear shifting. The transmission is mainly composed of input and output shafts, planetary gear sets, brakes/clutches, and housing, and it yields multiple forward gears and one reverse gear by actuating the shifting devices of the brakes and clutches. In developing a new transmission, kinematic configurations of a transmission, which presents a brief structure and actuation schemes for speed ratios, need to be checked to determine if the structure can be assembled in a layout. It is impossible for a transmission concept having any interference in connecting main components to be developed further in the design process, since connection interference leads to failure of a layout design in the 2-D plane. In this research, an analysis of the assemblability of a front-wheel drive automatic transmission is carried out on an example concept design by applying the vertex addition algorithm based on graph theory.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2013년도 춘계학술대회
• /
• pp.578-580
• /
• 2013

최근 스마트 디바이스의 증가에 따라 개인이 휴대하는 장치가 증가하고 있으며, 대부분의 스마트 디바이스에는 블루투스가 기본사양으로 탑재되고 있다. 그러나 블루투스 장치의 연결 제한으로 다중연결을 활용한 서비스 제공은 미흡한 상태이며, 다중연결이 가능하더라도 설정된 장치가 모두 접속되어야 데이터 통신이 가능한 문제점이 존재한다. 본 논문에서는 이러한 문제점을 해결하기 위한 방안으로 AT Command를 활용한 TDM(time division multiplexing) 방식의 다중연결 알고리즘을 제안하였다. 시뮬레이션을 통해 다수의 장치가 실시간 접속 및 데이터 전송이 가능하다는 것을 확인하였다.

• Journal of information and communication convergence engineering
• /
• 제3권2호
• /
• pp.93-95
• /
• 2005

In order to create security session, security keys are preconfigured between communication objects. For this purpose, Handshake Protocol exists. The pre-master secret key that is used in this process needs to interpreted by a server to create master secret key, whose process requires a big calculation, resulting in deteriorating system's transmission performance. Therefore, it is helpful in increasing transmission speed to reuse secret keys rather than to create them at every connection.

• ETRI Journal
• /
• 제28권1호
• /
• pp.99-102
• /
• 2006

In this letter, we study the protection problem in wavelength division multiplexing (WDM) optical networks, and propose a novel dynamic heuristic algorithm called differentiated reliable segment protection (DRSP). Differing from previous work, DRSP can effectively avoid the trap problem and is able to find a feasible solution for each connection request. Therefore, DRSP outperforms the previous work. Simulation results have shown to be promising.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 2000년도 추계학술대회 학술발표 논문집
• /
• pp.231-234
• /
• 2000

In this paper, we formed a transmitter and receiver by using three identical Chuas circuits and then formed wire and wireless transmission line from the channel which was between those three circuits. We proposed a secure communication method in which the desired information signal was synthesized with the chaos signal created in a Chuas circuit and sent to the transmitter through channel. Then the signal was demodulated receiver of Chuas circuit. The method we used to accomplish the secure communication was synthesizing the desired information with the chaos circuit by parallel connection in a wireless transmission line. After transmitting the synthesized signal to the wire and wireless transmission line, we confirmed the actuality of the secure communication by separating the information signal and the chaos signal in the receiver.

• 대한전기학회논문지:전력기술부문A
• /
• 제52권12호
• /
• pp.713-721
• /
• 2003

This paper analyzes the switching overvoltage occurred on 345kV underground power cable system as well as combined transmission system using EMTP. Cable length and closing time, preinsertion resistance have effect on switching overvoltage. Therefore, this paper analyzes the switching overvoltage occurred on conductor and sheath with change of those parameters. Specially, the cross bonding position becomes discontinuity point because of the difference between surge impedance of metal sheath and that of lead cable. Thus, the transmission and the reflection of traveling wave complexly occur at this connection point. According to these influences, voltage between sheath and earth as well as voltage between joint boxes rise. Time to crest point of switching overvoltage is longer than lightning overvoltage. Even though the voltage induced by switching surge is smaller than lightning surge, that voltage may have serious effect on the metal sheath. Therefore, this paper also analyses the reduction effect of switching overvoltage when the preinsertion resistance of circuit breaker is considered.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
• /
• pp.898-902
• /
• 1987

An end-to-end connect ion between customers on a network such as the PSTN (Public Switched Telephone Network) requires a number of internal connection ammong pieces of transmission, switching and signaling equipment. New switching, transmission, and station systems, as well as new features for existing systems, are continually being developed. and the complexities are such that ensuring compatibility of signaling arrange.ent is a major concern. In this paper, we propose that new signal interface using features of SPC(Stored Program Control) and digital transmission has to be introduced into the domestic telecommunications network in the near future.