• 한국통신학회논문지
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• 제33권8B호
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• pp.609-614
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• 2008

TDM-PON의 상향전송 데이터 프레임은 여러 가지 오버헤드를 포함하고 있으며, 각 ONU 전송시간 사이에는 가드밴드가 존재한다. 이들은 수신단의 동기 및 전송성능 유지를 위해 중요한 요소들이지만, 상향 대역폭 낭비의 원인이 되고 있다. 본 논문에서는 상향 전송에 두 종류의 파장을 이용해 대역폭 이용효율을 극대화하는 방식의 TDM-PON을 제안하였다. ONU들에 두 파장을 고르게 배치하고, 각 ONU는 전송 패킷의 오버헤드를 중첩하여 전송함으로써 이용 효율을 100%에 근접하도록 하였으며, 이를 위한 OLT 다중화회로를 구현하였다.

• Journal of Communications and Networks
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• 제15권2호
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• pp.122-131
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• 2013

We address the problem of effective vehicular routing in hostile scenarios where malicious nodes intend to jeopardize the delivery of messages. Compromised vehicles can severely affect the performance of the network by a number of attacks, such as selectively dropping messages, manipulating them on the fly, and the likes. One of the best performing solutions that has been used in static wireless sensor networks to deal with these attacks is based on the concept of watchdog nodes (also known as guard nodes) that collaborate to continue the forwarding of data packets in case a malicious behavior in a neighbor node is detected. In this work, we consider the beacon-less routing algorithm for vehicular environments routing protocol, which has been previously shown to perform very well in vehicular networks, and analyze whether a similar solution would be feasible for vehicular environments. Our simulation results in an urban scenario show that watchdog nodes are able to avoid up to a 50% of packet drops across different network densities and for different number of attackers, without introducing a significant increase in terms of control overhead. However, the overall performance of the routing protocol is still far from optimal. Thus, in the case of vehicular networks, watchdog nodes alone are not able to completely alleviate these security threats.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1089-1092
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• 1998

Conventional floating-point adders have one data-path that is used for all operations. This paper describes a floatingpoint adder eeveloped for low power consumption, which has three data-paths one of which is selected according to the exponent difference. The first is applied to the case that the absolute exponent difference (AED) of two operands is less than 1, and the second is for 1

• 한국안전학회지
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• 제28권4호
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• pp.91-96
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• 2013

Forklift truck is one of the dangerous machines which causes the fatal accidents most frequently. The causes of fatalities by forklift from 2008 to 2011 were analyzed. Crushing the operator when tipping over or falling off a truck were the major causes of death in this study. The purpose of this study is to show measures from the engineering point of view to prevent the forklift truck accidents. In order for that, the domestic requirement for forklift safety was compared with those of foreign and international standards. The manufacturers' opinion was also collected regarding to improve the forklift safety. Several measures were suggested in order to prevent fatalities caused by forklift.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2013년 춘계학술대회
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• pp.41-52
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• 2013

Forklift truck is one of the dangerous machines which causes the fatal accidents most frequently. The causes of fatalities by forklift from 2008 to 2011 were analyzed. Crushing the operator when tipping over or falling off a truck were the major causes of death in this study. The purpose of this study is to show measures from the engineering point of view to prevent the forklift truck accidents. In order for that, the domestic requirement for forklift safety was compared with those of foreign and international standards. The manufacturers' opinion was also collected regarding to improve the forklift safety. Several measures were suggested in order to prevent fatalities caused by forklift.

• 정보처리학회논문지C
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• 제9C권2호
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• pp.283-292
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• 2002

본 논문에서는 무선/이동 인터넷 환경에서 실시간 트래픽의 QoS 보장을 위한 자원 관리 기법에 대해서 연구한다. 이동단말은 이동성때문에 실시간 응용 서비스에서 요구하는 QoS에 중요한 영향을 갖는다. 현재 제안된 MRSVP는 자원 예약 지역 경계의 불명확성과 또한 세션들을 유지하기 위한 신호 과부하를 발생시킬 수 있다. 이러한 문제를 해결하기 위해, MRSVP[1-5]와 이동 클러스터 개념을 조합한 신규자원 예약 프로토콜-이동클러스 기반의 H-MRSVP(Hierarchical MRSVP)-을 제안한다. 본 논문에서는 실시간 이동 호에 대한 이동 클러스터 기반의 H-MRSVP의 분석적인 모델을 설계하고, 시뮬레이션을 이용하여 보호채널 할당 방식, 분산 호 수락제어 기법과 비교 분석한다. 성능 목표값으로는 신규호 차단율, 핸드오프 호 손실율, 무선 시스템에서이 채널 이용율과 호의 서비스 완료율을 보았다. 결과적으로 제안된 기법이 DCA보다는 채널 이용율 측면에서 좀더 유연하고, 보호채널기법보다는 이동호에 대한 좋은 채널 할당을 한다.