• Title/Summary/Keyword: 손실회피

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A study on how to generate notification messages using live and forecast information (실황 및 예측정보를 활용한 알림 메시지 생성방안 연구)

  • Lee, Jae-Young;Shin, Jiyoung;Park, Gi-Yeon;Kim, Junho
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2022.06a
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    • pp.158-160
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    • 2022
  • 최근의 자연 재난의 발생 빈도의 증가는 재난에 대한 정보전달의 중요성이 높아지는 만큼 전달 방법의 중요도도 높아지고 있다. 특히, 2020년의 코로나19(COVID-19)로 인하여 자연 재난에 더해 사회재난에 관한 관심도 증대하고 있으나, 재난정보의 빈도가 매우 높아져, 2000년대 통틀어서 제공된 재난 정보량보다 20년, 21년의 재난 정보량이 더 많아 보인다. 이러한 재난정보의 홍수는 반대급부로 정보의 피로도를 증가시켜 의도적 또는 비의도적 무시 경향을 유발할 수 있다. 이에 본 논문에서는 재난 위험지역을 기반으로 Segment를 생성하고 관리하며, Segment 단위로 재난 위험 메시지를 제공하는 Segment기반 긴급메시지전송 시스템을 연구한다. 목표시스템에서는 재난정보를 실황 정보와 1시간 예측정보를 비교, 위험지역 회피시나리오를 지능화 개선하여 모바일앱 이용자에게 제공함으로써 대피 이동관리와 행동 유도를 이끌어 이용자의 인명피해 저감과 재산손실 감소의 효과를 얻고자 개발하였다.

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An Empirical Study on the Effect of Respondent Bias in PSM : Case in Apartment Pricing (PSM 가격평가 주체에 따른 아파트 가격결정 효용성 실증연구)

  • Cho, Han-Jin;Kim, Jong-Lim
    • Land and Housing Review
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    • v.7 no.4
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    • pp.217-223
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    • 2016
  • PSM is widely used pricing tool in field by the reason of data collection convenience and analytical intuitiveness. However, In high involvement environment, strategic respondent bias influence in reducing the price. By using 3 empirical cases of LH apartment for sale, We found that latent consumers' recognition of the range of acceptable and the range of optimal price are lower than real estate agent representative respondents'. This phenomenon is considered loss aversion effect of prospect theory to reduce loss by reducing price, and more influenced in high involvement situation than latent consumer respondents'. Also we found PSM result using real estate representative data is more useful in real market than latent consumers data distorted by loss aversion effects. The meaning of this study is finding some limitation in PSM using consumer data generally used. In further study, development of PSM measurement tool to minimize the effect of strategic bias are need to be studied. Also some new approaches in reinterpretation of the range of acceptable price and the range of optimal price are need to be followed.

Study of Impact on COMS Fuel Consumption by East-West Station Keeping Maneuver Time Shift to Avoid Conflict with the Observation of Full Disk or Similar Meteorological Images (전구 및 유사 기상영상 관측임무와 충돌을 회피하기 위한 동서방향 위치유지기동의 시간 이동이 천리안위성 연료소모에 미치는 영향 연구)

  • Cho, Young-Min
    • Aerospace Engineering and Technology
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    • v.11 no.1
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    • pp.103-110
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    • 2012
  • In the COMS satellite mission operation, more large meteorological images such as Full Disk(FD) image or 2 adjacent Extended Northern Hemisphere(ENH) images can be taken by the time shift of East West Station Keeping(EWSK) maneuver when the EWSK conflicts with the large images. In this study an analytical approach based on probability of the conflict is proposed for theoretical analysis about the EWSK time shift to avoid the conflict with FD or 2 ENH images. The EWSK time shift has been applied to the COMS operation as a test, too. The theoretical study result and test operation outcome are synthesized to provide the analysis of impact on the COMS fuel consumption by the EWSK time shift. This study is expected to contribute to the maximization of COMS meteorological mission application.

Lazy Garbage Collection of Coordinated Checkpointing Protocol for Avoiding Sympathetic Rollback (동기적 검사점 기법에서 불필요한 복귀를 회피하기 위한 쓰레기 처리 기법)

  • Chung, Kwang-Sik;Yu, Heon-Chang;Lee, Won-Gyu;Lee, Seong-Hoon;Hwang, Chong-Sun
    • Journal of KIISE:Computer Systems and Theory
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    • v.29 no.6
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    • pp.331-339
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    • 2002
  • This paper presents a garbage collection protocol for checkpoints and message logs which are staved on the stable storage or volatile storage for fault tolerancy. The previous works of garbage collections in coordinated checkpointing protocol delete all the checkpoints except for the last checkpoints on earth processes. But implemented in top of reliable communication protocol like as TCP/IP, rollback recovery protocol based on only last checkpoints makes sympathetic rollback. We show that the old checkpoints or message logs except for the last checkpoints have to be preserved in order to replay the lost message. And we define the conditions for garbage collection of checkpoints and message logs for lost messages and present the garbage collection algorithm for checkpoints and message logs in coordinated checkpointing protocol. Since the proposed algorithm uses process information for lost message piggybacked with messages, the additional messages for garbage collection is not required The proposed garbage collection algorithm makes 'the lazy garbage collectioneffect', because relying on the piggybacked checked checkpoint information in send/receive message. But 'the lazy garbage collection effect'does not break the consistency of the whole systems.

Study on Fraud and SIM Box Fraud Detection Method in VoIP Networks (VoIP 네트워크 내의 Fraud와 SIM Box Fraud 검출 방법에 대한 연구)

  • Lee, Jung-won;Eom, Jong-hoon;Park, Ta-hum;Kim, Sung-ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.10
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    • pp.1994-2005
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    • 2015
  • Voice over IP (VoIP) is a technology for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks. Instead of being transmitted over a circuit-switched network, however, the digital information is packetized, and transmission occurs in the form of IP packets over a packet-switched network which consist of several layers of computers. VoIP Service that used the various techniques has many advantages such as a voice Service, multimedia and additional service with cheap cost and so on. But the various frauds arises using VoIP because VoIP has the existing vulnerabilities at the Internet and based on complex technologies, which in turn, involve different components, protocols, and interfaces. According to research results, during in 2012, 46 % of fraud calls being made in VoIP. The revenue loss is considerable by fraud call. Among we will analyze for Toll Bypass Fraud by the SIM Box that occurs mainly on the international call, and propose the measures that can detect. Typically, proposed solutions to detect Toll Bypass fraud used DPI(Deep Packet Inspection) based on a variety of detection methods that using the Signature or statistical information, but Fraudster has used a number of countermeasures to avoid it as well. Particularly a Fraudster used countermeasure that encrypt VoIP Call Setup/Termination of SIP Signal or voice and both. This paper proposes the solution that is identifying equipment of Toll Bypass fraud using those countermeasures. Through feature of Voice traffic analysis, to detect involved equipment, and those behavior analysis to identifying SIM Box or Service Sever of VoIP Service Providers.

Earnings Management and Cost Stickiness: Evidence from Mongolia (몽골기업의 이익조정과 원가의 하방경직성)

  • Ser-Od, Bolortuya;Koo, Jeong-Ho
    • Journal of Industrial Convergence
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    • v.20 no.9
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    • pp.25-38
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    • 2022
  • The purpose of this paper is to verify the cost behavior of non-listed companies in Mongolia from 2013 to 2018. And we investigate the relationship between cost behavior and earnings management. Earnings management was measured using the Big-Bath and avoiding loss incentives. Big-Bath suspected firms report a very large loss and avoiding loss suspected firms have a bite profit. The results of this study are as follows. First, non-listed firms in Mongolia, operating costs(oc) and selling, general and administrative(sga) costs show the cost stickiness. Second, cost stickiness was different depending on the earnings management. The suspected avoiding loss firms have upward earnings management incentives, operating costs and sga costs all present anti-cost stickiness. The suspected big bath firms strengthen the cost stickiness of operating costs and sga costs. This study is meaningful in that it first analyzed the relationship between earnings management and cost stickiness of non-listed firms in Mongolia using empirical data. It will be meaningful in that it provides relevant information to those interested in research and investment.

Performance Evaluation of TCP over Wireless Links (무선 링크에서의 TCP 성능 평가)

  • Park, Jin-Young;Chae, Ki-Joon
    • Journal of KIISE:Information Networking
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    • v.27 no.2
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    • pp.160-174
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    • 2000
  • Nowadays, most widely used transport protocol, TCP is tuned to perform well in traditional networks where packet losses occur mostly because of congestion. TCP performs reliable end-to-end packet transmission under the assumption of low packet error rate. However, networks with wireless links suffer from significant losses due to high error rate and handoffs. TCP responds to all losses by invoking congestion control and avoidance algorithms, resulting in inefficient use of network bandwidth and degraded end-to-end performance in that system. To solve this problem, several methods have been proposed. In this paper, we analyse and compare these methods and propose appropriate model for improving TCP performance in the network with wireless links. This model uses TCP selective acknowledgement (SACK) option between TCP ends, and also uses caching method at the base station. Our simulation results show that using TCP SACK option with base station caching significantly reduces unnecessary duplicate retransmissions and recover packet losses effectively.

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Enhanced TCP Congestion Control Mechanism for Networks with Large Bandwidth Delay Product (대역폭과 지연의 곱이 큰 네트워크를 위한 개선된 TCP 혼잡제어 메카니즘)

  • Park Tae-Joon;Lee Jae-Yong;Kim Byung-Chul
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.3 s.345
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    • pp.126-134
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    • 2006
  • Traditional TCP implementations have the under-utilization problem in large bandwidth delay product networks especially during the startup phase. In this paper, we propose a delay-based congestion control(DCC) mechanism to solve the problem. DCC is subdivided into linear and exponential growth phases. When there is no queueing delay, the congestion window grows exponentially during the congestion avoidance period. Otherwise, it maintains linear increase of congestion window similar to the legacy TCP congestion avoidance algorithm. The exponential increase phase such as the slow-start period in the legacy TCP can cause serious performance degradation by packet losses in case the buffer size is insufficient for the bandwidth-delay product, even though there is sufficient bandwidth. Thus, the DCC uses the RTT(Round Trip Time) status and the estimated queue size to prevent packet losses due to excessive transmission during the exponential growth phase. The simulation results show that the DCC algorithm significantly improves the TCP startup time and the throughput performance of TCP in large bandwidth delay product networks.

Architecture and Characteristics of Multi-Ring based Optical Network with Single-Hop between Edge Nodes (Edge Node간 단일 홉을 갖는 다중링 기반의 광네트워크 구성 및 특성)

  • Lee, Sang-Hwa;Lee, Heesang;Han, Chimoon
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.6 s.324
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    • pp.69-78
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    • 2004
  • This paper proposes architecture and characteristics of a multi-ring based optical network with single-hop between edge nodes using the concept of circuit switching and multi-wavelength label switching to solve delay problem caused by applying crossconnectors as transit nodes in the wavelength division multiplexing(WDM) network. We suggest multi-ring based architecture composed single and multiple wavelength-bands with multi-wavelength labels, and analyze characteristics of two models. To avoid the packet collision in output ports of edge nodes due to output contention, the static and dynamic allocation scheme, which packets are allocated in time slots, is provided. Based on our analysis, it shows that delay only occur in not core nodes but edge nodes in the proposed architecture. In addition, we evaluate the probabilities of delay, packet loss, and call blocking in the proposed optical packet network.

A Packet Dropping Algorithm based on Queue Management for Congestion Avoidance (폭주회피를 위한 큐 관리 기반의 패킷 탈락 알고리즘)

  • 이팔진;양진영
    • Journal of Internet Computing and Services
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    • v.3 no.6
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    • pp.43-51
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    • 2002
  • In this paper, we study the new packet dropping scheme using an active queue management algorithm. Active queue management mechanisms differ from the traditional drop tail mechanism in that in a drop tail queue packets are dropped when the buffer overflows, while in active queue management mechanisms, packets may be dropped early before congestion occurs, However, it still incurs high packet loss ratio when the buffer size is not large enough, By detecting congestion and notifying only a randomly selected fraction of connection, RED causes to the global synchronization and fairness problem. And also, it is the biggest problem that the network traffic characteristics need to be known in order to find the optimum average queue length, We propose a new efficient packet dropping method based on the active queue management for congestion control. The proposed scheme uses the per-flow rate and fair share rate estimates. To this end, we present the estimation algorithm to compute the flow arrival rate and the link fair rate, We shows the proposed method improves the network performance because the traffic generated can not cause rapid fluctuations in queue lengths which result in packet loss

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