• Proceedings of the KIEE Conference
• /
• 2007.04b
• /
• pp.88-90
• /
• 2007

본 논문에서는 배선용 차단기 단자와 전선간의 접속결함에 의한 아크발생 및 화재위험성을 분석하였다. 실험 및 분석에 사용된 배선용 차단기는 단상 2선식의 국내외 제품으로 외형분석결과 단자구조는 제품마다 상이하였으며, 단자와 전선간의 접촉저항 측정결과 국내 제품은 접속방식에 따라 접촉저항의 편차가 컸다. 배선용 차단기 단자와 전선간 접속결함에 의한 접촉불량 발생시 단자구조에 따른 아크 및 화염의 특성 실험의 부하조건으로는 저항부하를 사용하였으며, 가진기의 축에 배선용차단기를 설치하여 진동에 의한 영향을 받도록 하였다. 인가시간은 10[분]으로 하였으며, 접촉불량이 진전됨에 따라 배선용 차단기 단자에 아크가 지속적으로 발생하였다. 대략 수분이 경과한 후 차단기가 차단되는 경우도 있었으며, 차단되지 않는 경우도 있었다. 또한 4개사의 제품 중 1개사의 제품은 접속단자 주변 절연재료로 아크에 의한 화염전이가 용이하였다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.5
• /
• pp.1101-1105
• /
• 2013

Due to underutilization of spectrum under the current static spectrum management policy, various kinds of dynamic spectrum access strategies have appeared. Myopic policy is a simple policy with reduced complexity that maximizes the immediate throughput. In this paper, the distribution of its medium access delay is evaluated under saturation traffic conditions. Using the distribution of the medium access delay, we also evaluate its system delay under non-saturated traffic conditions.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2018.10a
• /
• pp.936-938
• /
• 2018

본 논문은 IoT 환경에서 MQTT 대량 브로커와 대량 클라이언트간 효율적인 접속을 지원하기 위해 대량 접속처리 기능을 제공하는 CA(Connectionb Agent)를 포함한 MQTT 메시지 서버를 설계, 구현하였다. MTQQ 프로토콜은 MQTT 브로커와 MQTT 클라이언트로 구성되며, 각 MQTT 클라이언트는 MQTT 브로커의 중재를 받아 Pub/Sub 방식으로 메시지를 상호 전송한다. 이를 위해 MQTT 프로토콜은 MQTT 브로커와 MQTT 클라이언트 간 접속기능만을 제공한다. 실험결과에서 MQTT 메시지 서버는 초당 평균 12,500 건의 클라이언트 접속요청을 처리하였고, 20만건의 접속요청 처리에 16초가 소요되었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.686-689
• /
• 2009

NGN은 기존의 회선교환망이 가지는 높은 신뢰성과 IP 망의 유연성을 양립시킨다는 기본 이념을 바탕으로 IP 기술을 활용한 통신망이다. 상호접속은 서로 다른 통신망의 가입자간 통신을 가능하도록 통신설비를 물리적으로 연결하여 사업자간 경쟁환경을 조성하고 사회 후생을 극대화를 위한 중요한 정책수단이다. NGN에서는 사용대역차이와 QoS의 유무 및 수준 등 성격이나 품질이 다양한 서비스가 종합적으로 제공되는 네트워크로 기존 상호접속체계에 비해 복잡할 수 밖에 없다. 일본에서는 NGN 기반 서비스가 상용화 됨에 따라 구체적으로 상호접속체계를 정립하였다. 본 논문에서 NGN 상호접속체계를 정립하기 위한 NGN 서비스 및 설비 기능 세분화, 설비 비용 산정방법, 서비스 비용 산정기준에 관하여 살펴보고 상호접속체계 검토시 고려사항을 제시하고자 한다.

• Electric Engineers Magazine
• /
• v.194 no.10
• /
• pp.23-26
• /
• 1998

CT를 3상 회로에 접속하는 경우 접속방식에 따라 흐르는 전류가 어떻게 될까 하는 것을 아는 것은 전류계의 지시, 전기보호 등을 이해하는데 있어 대단히 중요하면서도 필요하다. 그러므로 여기서는 이에 대해 기술하고자 하며, 이에 앞서 변류기의 이론을 살펴본 뒤 본론으로 들어가고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.5
• /
• pp.393-400
• /
• 2013

In conventional single-tier networks, downlink based association is the best association scheme for the uplink association because all macro base stations have the same physical specification. However, in uplink heterogeneous cellular networks, a downlink based cell association cannot be the best for uplink any more because of the difference of physical specification between the different base station. In this paper, we will propose a uplink based cell association scheme, and devise performance metric for describing a uplink performance in heterogeneous cellular networks. Then, we will discuss the necessity of the uplink based association by observing outage probability, delay constraint outage probability, delay constraint outage capacity.

• KEPCO Journal on Electric Power and Energy
• /
• v.5 no.4
• /
• pp.295-309
• /
• 2019

This paper demonstrates that the verification and analysis of the increase of hosting capacity of distributed energy resources in distribution system for the high penetration of distributed energy resources. In the case of generally designed distribution feeders in South Korea, it can host up to 10 MVA of distributed energy resources and the over voltage due to reverse power flow is prohibited beyond the range by the law of electric utility. However, it should take into consideration that there are some factors of extra hosting capacity such as generation characteristics of distributed energy resources and minimum loads that always exist to distribution system. For these reason, we choose a specific distribution system hosted 10 MVA of distributed energy resources monitored by distribution system operator and verify the impact of increasing hosting capacity such as power flow and voltage profile of distribution system. By the result, we could find that it is possible to increase the hosting capacity and define the factors to expand the hosting capacity of distributed energy resources in distribution system.

• Journal of the Korean Data and Information Science Society
• /
• v.27 no.3
• /
• pp.701-710
• /
• 2016

The purpose of this paper is to build a model of packet amount of Naver mobile portal. We collected 2004 cases by measuring the sixth per access from September, 2012 to October, 2015. We use regression model with autoregressive errors, in which predictors incorporated into the model were replication, date, time, week, month. It has been found the model which errors follow AR(36), based on AIC and adjusted $R^2$. We found some characteristics from our model as follows. In addition to model building, we also have discussed some meaningful features yielded from the selected model in this paper. Considering the importance of this topic, continuous researches are needed.

• Fire Science and Engineering
• /
• v.16 no.3
• /
• pp.8-11
• /
• 2002

Recently, the spark and the overheat due to in the failure of pressure contacts on connecting points and the momentary short circuit have been the major causes of electrical fire because these may cause the deposition and the graphite of insulating materials in electrical wiring system. Also, because in these cases the current is a surge one, the losses and faults of a communication, a home appliances, a computer and a measuring instrument may occur. Especially, in such cases, we are very difficult to detect the failure of pressure contacts on connecting points and the momentary short circuit. In this paper, we have developed an auxiliary control device, the electrical fire prevention control device(EFPCD), of an earth leakage breaker(ELB). And we can pre-vent the electrical fire caused by the spark and the overheat occurring in the failure of pressure contacts in connecting points and the momentary short circuit with the EFPCD.

• Journal of the Microelectronics and Packaging Society
• /
• v.15 no.4
• /
• pp.9-15
• /
• 2008

Microstructure and contact resistance of the Au-Sn solder joints were characterized after flip-chip bonding of the Au/Sn bumps processed by successive electrodeposition of Au and Sn. Microstructure of the Au-Sn solder joints, formed by flip-chip bonding at $285^{\circ}C$ for 30 sec, was composed of the $Au_5Sn$+AuSn lamellar structure. The interlamellar spacing of the $Au_5Sn$+AuSn structure increased by reflowing at $310^{\circ}C$ for 3 min after flip-chip bonding. While the Au-Sn solder joints formed by flip-chip bonding at $285^{\circ}C$ for 30 sec exhibited an average contact resistance of 15.6 $m{\Omega}$/bump, the Au-Sn solder joints reflowed at $310^{\circ}C$ for 3 min after flip-chip bonding possessed an average contact resistance of 15.0 $m{\Omega}$/bump.