• Journal of the Korean Institute of Gas
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• v.28 no.2
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• pp.24-31
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• 2024

In the chemical industry, fires and explosions constantly occur due to runaway reactions during the production of various chemical products. To prevent this, much research has been conducted, and the possibility of runaway reactions for each substance is reviewed and interlocking devices are installed to prepare for adverse reactions to prepare for fires and explosions. However, despite legal and technical safety measures, accidents due to runaway reactions still occur every year. Accordingly, in this study, based on cases of fire and explosion accidents in styrene monomer reactors, the discharge capacity during runaway reactions was examined through experiments and graphs. Unlike the commonly calculated fire equation, in the case of a runaway reaction where pressure and temperature increase rapidly, discharge is made in two phases rather than a single phase, so the size of the rupture disk must also increase, and the orientation must be adjusted before the rupture disk is installed at the top of the pressure vessel. It was found that position adjustment was necessary.

• Journal of Broadcast Engineering
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• v.19 no.1
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• pp.44-55
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• 2014

The goal of 3D stereoscopy is not only to maximize positive experiences (such as sense of realism) by adding depth information to 2D video but to also minimize negative experiences (such as fatigue). This study examines the impact of different depth levels induced by adjusting 3D camera convergences on positive and negative experiences and finds an optimal parameter for viewers. The results show that there are significant differences among depth levels on spatial involvement, realistic immersion, presence, depth perception, screen transmission, materiality, shape perception, spatial extension and display perception. There are also significant differences for fatigue and unnaturalness. This study suggests that reducing the camera convergence angle of an object by $0.17^{\circ}$ behind the object is the optimal parameter in a 3D stereoscopic setting.

• 공원문화
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• s.39.40
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• pp.58-59
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• 1988

국.도.군립 등 자연공원의 보호와 이용에 대한 도하각신문 기사의 초점은 모든 개발도상국들이 겪듯이 보호보다 이용.개발쪽에 시각을 높혀 지역민의 경제발전과 연계하려는 경향이 짙다. 더욱이 보호의식의 희박으로 환경오염의 심각성은 폭주하는 이용객과 정비례하는 적신호를 울리고 있어 보호의식의 선양이 초급하다. 참고로 최근 각신문(전문지 포함)에 비친 국립공원 등 자연공원에 관한 기사의 제목만이라도 엮어 매스콤의 초점을 살펴 연구자료로 삼고저 한다.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.1
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• pp.39-43
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• 2007

In high speed communication networks, the determination of a transmission rate is critical for the stability of a closed-loop network system with the congestion control scheme. In ATM networks, the available bit rate (ABR) service is based on a feedback mechanism, i.e., the network status is transferred to the ABR source by a resource management (RM) cell. RM cells contain the traffic information of the downstream nodes for the traffic rate control. However, the traffic status of the downstream nodes can not be directly transferred to the source node in the IP based networks. In this paper, a new rate-based congestion control scheme using an exponential weighted moving average algorithm is proposed to build an efficient feedback control law for congestion avoidance in high speed communication networks. The proposed congestion control scheme assures the stability of switch buffers and higher link utilization of the network. Moreover, we note that the proposed congestion scheme can flexibly work along with the increasing number of input sources in the network, which results in an improved scalability.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.9
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• pp.28-34
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• 1998

In ATM networks CBR data traffic is sent in constant bit rate, and VBR data traffic in variable bit rate. Therefore unused bandwidth at network capacity may exist. To avoid waste of network resourcesm, ABR traffic utilizes the unused bandwidth to the utmost after CBR and VBR data traffic being first served. In this paper, a transfer rate-based congestion control algorithm is proposed for efficient ABR service in ATM networks. In the proposed algorithm the ATM switch first calculates bandwidth according to variable cell transfer rate in an ABR source. records this value in ER field in a RM cell, and then transmits a RM Cell to an ABR source. In this way the proposed algorithm dynamically allocates bandwidth to each ABR source, and the switch also can rapidly adapt to a change of a transfer rate of an source. The performance simulation of the proposed algorithm has batter performance in terms of source condition and link utilization.

• Annual Conference of KIPS
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• 2002.04a
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• pp.75-78
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• 2002

데이타베이스 공유 시스템(Database Sharing System: DSS)은 고성능의 온라인 트랜잭션 처리를 위해 다수 개의 컴퓨터를 연동하는 방식으로 각 노드들은 디스크 계층에서 데이타베이스를 공유한다. DSS를 구성하는 각 노드에 트랜잭션을 할당하는 정책이 잘못될 경우 특정 트랜잭션의 폭주로 노드에 과부하가 발생할 수 있으므로. 각 노드의 성능을 최적화하기 위한 부하 분산이 필요하다. 본 논문에서는 트랜잭션 클래스에서 참조하는 데이터베이스의 핫 셋 크기, 각 노드의 메모리 크기와 CPU 성능, 동시에 실행되는 트랜잭션 수의 변화에 따른 처리량 등을 고려한 동적 부하 분산 기법을 제안한다.

• The Transactions of the Korea Information Processing Society
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• v.5 no.5
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• pp.1311-1319
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• 1998

The methods of providing available bandwidth adaptively using feedback to maximize the utilization of network as well as the quality of service have been the focus of recent research activities for ATM(Asynchronous Transfer Mode). This study has been extended from the point-to-point connection to a point-to-multipoint environment as the number of applications requiring multicast service increases. It is known that the effectiveness of feedback based congestion control scheme diminishes as propagation delay increases. Especially for a multicast connection consisting of various paths and destinations with different performance and congestion status, the problem of unfairness due to different propagation delays may occur. The degree of such unfairness may change depending on various aspects of congestion control schemes. These has been, however, relatively little study on these problems. In this paper, we present how various aspects of control schemes-length of the interval between feedback generations, point of time to coalesce feedback cells from child paths, decreasing factor of source rate in case of congestion-affect the degree of unfairness. Simulation results show that degree of unfairness changes according to when the feedback coalescing happens. Expecially it is shown that the effect of feedback coalescing time to the degree of unfairness is more significant for the smaller feedback interval. It is also found that as the source rate decreasing factor becomes larger the average ACR(Allowed Cell Rate) at the source gets lower and the degree of unfairness grow larger.

• Journal of Internet Computing and Services
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• v.2 no.2
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• pp.65-70
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• 2001

In this paper, a Modified RED algorithm for congestion avoidance in IP networks is presented. The RED detects incipient congestion by computing the average queue size. By notifying only a randomly selected fraction of connection, it causes to the global synchronization or fairness problem, And also, the network characteristics need to be known in order to find th optimum average queue length. When the average queue size exceeds a minimum threshold, a modified RED algorithm drops packets based on the state of each connection. Performance is improved because of keeping the average queue size low while allowing occasional bursts of packets in the queue, we compare performance of modified RED with RED and Drop Tail in terms of goodput, network utilization and fairness.

• Annual Conference of KIPS
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• 2008.11a
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• pp.1496-1499
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• 2008

DoS/DDoS로 대표되는 트래픽 폭주 공격은 대상 시스템뿐만 아니라 네트워크 대역폭 및 시스템 자원 등을 고갈시킴으로써 네트워크에 심각한 장애를 유발하기 때문에, 신속한 공격 탐지와 공격유형별 분류는 안정적인 서비스 제공 및 시스템 운영에 필수요건이다. 본 논문에서는 1) 데이터마이닝의 대표적인 분류 모델인 C4.5 알고리즘을 기반으로 SNMP MIB 정보를 사용하여 트래픽 폭주공격을 탐지하고 각 공격유형별 분류를 수행하는 시스템을 설계 및 구현하였다; 2) C4.5에서 추가적으로 제공하는 동작원리에 관한 규칙들을 상세히 분석함으로써 공격탐지 및 공격유형별 분류에 관한 시스템의 의미론적 해석을 시도하였다; 3) C4.5는 주어진 SNMP MIB의 속성들의 정보이익 값을 이용하여 예측모형을 구축하는 알고리즘으로, 특징선택 및 축소의 효과를 추가적으로 얻었다. 따라서 시스템의 운용 시, 제안된 모델은 전체 13개의 MIB 정보 중 5개의 MIB 정보만을 사용하여 보다 신속하고, 정확하며, 또한 가벼운 공격탐지 및 공격유형별 분류를 수행함으로써 네트워크 시스템의 자원관리와 효율적인 시스템 운영에 기여하였다.

• Annual Conference of KIPS
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• 2000.10b
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• pp.1629-1632
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• 2000

인터넷 트래픽의 폭발적인 증가로 인해 라우터에서 목적지로 포워딩 해야 할 트래픽의 양도 함께 증가하게 되었다. 그와 같은 트래픽들 중에 최근에 급격히 증가하고 있는 음성트래픽의 주를 이루는 것이 바로 인터넷 전화로 발생되는 트래픽들이다. 본 논문에서는 인터넷 전화시 발생하는 음성트래픽의 특성에 대해 살펴보고, 라우터에서 트래픽 폭주시 이를 제어하는 큐잉 방식을 비교분석하고, MNS(MPLS Network Simulation)툴을 이용하여 코어망을 MPLS 네트워크로 구성한 후 UDP 음성트래픽을 생성하여 각 라우터(LSR: Label Switch Router)의 버퍼에서 요구되어지는 폭주제어기법들에 대해 시뮬레이션을 하여 그것을 통해 얻은 결과를 바탕으로 실제 인터넷 전화 시스템의 통화품질에 적절하게 대처할 수 있는 큐잉 기법을 고찰한다.