• The KIPS Transactions:PartC
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• v.8C no.4
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• pp.451-458
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• 2001

무단절 통신의 목표는 이동 사용자에게 단절 자유 서비스를 제공하는데 있으며, 이동 서비스의 단절은 활동적 핸드오프에 의해 발생된다. 이동 무선망에서 무단절 서비스에 대한 완전 보장을 요구하지 않으나 매우 빈번한 단절을 허용하지 않는 많은 사용자 응용들이 있다. 이 논문에서는 무단절 서비스에 대한 언어적 보장을 제공하는 퍼지 멀티캐스트 방법을 제안한다. 무단절 서비스에 대한 언어적 보장이 이동 사용자에 의해 명세되면, 제안하는 퍼지 멀티캐스트 방법은 이동 호스트의 이동 방향과 이동 속도를 예측하고, 퍼지 논리에 의해 그 이동 호스트를 위한 체이터 패텟은 모든 이웃 셀이 아닌 일부 이웃 셀에게 전송된다. 시뮬레이션 결과, 우리는 다음 사항들을 알 수 있었다. 첫째, 퍼지 멀티캐스트 방법은 정적 대역폭 사용을 상당히 감소시키고 또한 무단절 서비스에 대한 언어적 보장을 제공한다. 둘째, 무단절 서비스 확률은 이동 사용자의 언어적 QoS와 이동 호스트의 이동 방향에 의해 결정되고, 특히 이동 사용자의 언어적 QoS에 의해 많은 영향을 받는다. 그러므로 퍼지 멀티캐스트는 이동 사용자의 언어적 QoS 명세로 무단절 서비스에 대한 좋은 차등 서비스를 제공한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1755-1764
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• 1997

In this paper, we proposed the mechanism for the buffer allocation and a cell scheduling method with logical separation a single buffer in the ATm switch, and analyzed the cell loss probability and the delay of each trafic (CBR/VBR/ABR) based on the weighted value and the dynamic cell service scheduling algorithm. The proposed switch buffering system classifies composite trafics incoming to the switch, according to the characteristic of traffic, then stores them in the logically separated buffers, and adopts the round-robin service with weighted value in order to transmit cells in buffers though one output port. We analyzed 4 cell service scheduling algorithms with dynamic round-robinfor each logically separated service line of a single buffer, in which buffers have the respective weighted values and 3 classes on mixed traffic which characteristized by traffic descriptor. In simulation, using SIMCRIPT II.5., we model the VBR and the ABR traffics as ON/OFF processes, and the CBR traffic as a Poisson processes. As the results of analysis according to the proposed buffer management mechanism and cell service algorithm, we have found that the required QoS of each VC can be quaranteed depends on a scale of weighted values allocated to buffers that changed the weighted values, and cell scheduling algorithm.

• Journal of the Korea Society for Simulation
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• v.30 no.1
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• pp.1-9
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• 2021

In actual battlefield environment, the naval ships which have specific missions have to respond to the attack of hostile forces. Especially, in modern warfare, the importance of the survivability of naval ships are increasing due to the high lethality of armaments. Naval ship survivability is generally considered to encompass three constituents, susceptibility, vulnerability and recoverability. Recently, among these three constituents, many researches on vulnerability have been conducted. However, for the vulnerability of naval ships, most of researches are aimed towards the detailed design stages where implementing changes is heavily constrained or even impractical. In this paper, vulnerability assessment model for naval ships on a theater engagement is developed by using M&S technique. By using this model, the characteristics of platform and armaments are reflected on the damage of naval ship. The basic logic of damage assessment is also considered in detail. The damage status of the naval ship is quantified by defining a representative state index of onboard equipment for each system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1091-1097
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• 2022

In this paper, we implement the eXclusive OR-based Cast (XC) system that is a video streaming system using exclusive OR operations, and measure various performance metrics in wireless local area network (WLAN) environments. In addition, we investigate the performance improvement of the XC system considering various practical video streaming environments, while conventional studies analyzed the performance of XC through computer simulations in limited environments. To this end, we propose new control messages such as STR_REQ_MSG (SRM) that clients transmit to a video streaming server and STR_CON_MSG (SCM) that is used for the video streaming server to control the clients, and develop a new protocol by using the new control messages. According to the various measurement results using the implemented XC system, XC video streaming system can reduce the consumption of network bandwidth by 8.6% on average and up to 25% compared to the conventional video streaming system. In addition, the outage probability can be also reduced up to 76%.

• Korean Journal of Logic
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• v.20 no.1
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• pp.21-67
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• 2017

In this paper, I critically examine Sartorio's (2006) argument for disjunctive cause, and put forth disjunctive causal structure in a different way. I show that the disjunctive causal structure meets not just what Sartorio means to claim but also our understanding of causal responsibility. First, I introduce Sartorio's argument for disjunctive cause. Second, I critically discuss Sartorio's responses to the criticisms of her arguments for disjunctive cause, and propose another problem with her arguments. Finally, I explicate in a different way Sartorio's disjunctive cause in terms of disjunctive causal structure founded on moderate variables, causal interaction, and probability trajectory. I notice, regarding the disjunctive causal structure, the role of causal interaction of cause events with moderate variables. I reveal, regarding the disjunctive causal structure, the significance of indetermination of cause events and effect events for our understanding of causal responsibility. I show that the disjunctive causal structure guides us more convincingly to assign causal responsibility to an agent. I come to three conclusions. First, there is no disjunctive cause event Sartorio argues for. Second, propensities of events to be causally connected to an effect event constitute disjunctive relation. Third, we should notice indetermination of cause events and effect events while assigning causal responsibility to an agent.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.931-940
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• 2001

In this paper, I propose Fuzzy Policing Mechanism(FPM) over ATM networks for the control of traffic which is unpredictable and bursty source. The FPM is consist of counter, subtracter and Fuzzy Logic Controller(FLC). The FLC is divided to fuzzifier, inference engine and defuzzifer The output of FLC inputs to the subtractor and it controls the counter. The counter works as a switch in transmission of cells. In simulation, I compared the FPM with the Leaky Bucket algorithm(LBM) in cell loss probability and performance characteristics. As a result, FPM gives lower cell loss probability than that of LBM and has good response behavior The FPM efficiently controls the transmission of packets which are variable traffic source and, it also has good selectivity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.4
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• pp.301-308
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• 1991

In this paper, we have proposed a demodulation circuit of radio data receiver system and calculated the error probability of the digital transmitted signal corrupted under noise environment. And we have evaluated the error performance of the proposed system. The designed demodulation circuits have been implemented by using the general random logic and PLL circuits, which can be possible for the integrated circuit design of the radio data receiver system. In addition calculation of bit error rate in recovered digital signal has been accomplished ans we have confirmed that the proposed system hsa the equivalent performance with already existing ones.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.847-850
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• 1998

One of the most difficult problem of designing VLSI is a mixed-circuit design, that is to design circuit containing both analog parts and digital parts. Digital to analog converter and analog to digital converter is a typical case. Especially it can be a serious problem when mixed circuit are put into a large digital circuit like microcontroller. However nowadays this problem is settled by separating analog circuit parts outside the IC. This technique is based on converting a digital signal into a pulse sequence. Then an analog signal is obtained by averaging this pulse sequence at the external low-pass filter. An anlog to digital converter is designed using a stochastic logic instead of a traditional PWM (pulse-width modulation) signal and ins implemente dusing FPGa. Stochastic pulse sequence can be made as a simple circuits and moreover can be mathematically processed by simple circuits -AND gates. The spectral property of stochastic pulse sequence method is better than that of PWM method. So it make easy to design a external low-pass filter. This technique has important advantages, especially the reduction of the ADC cost.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.52-52
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• 2004

공리적 설계는 미국 매사추세츠 공과대학의 서남표 교수에 의해 창출되고 보급되어 온 설계이론이다. 그러나 좀 더 정확히 말한다면 설계이론 이라기보다는 일반적인 공학적 과정에 적용할 수 있는 원리를 포함하는 설계프레임워크라 할 수 있다. 기계공학에서의 역학과 같이 설계를 하기 위해서는 과학적인 기본원리에 따라 설계해야 한다는 것이다. 그러므로 공리적 설계는 설계과정에서 설계자에게 과학적 원리를 제공하여 설계자가 이성적이고 논리적으로 설계를 진행할 수 있도록 하여, 시행착오를 줄이며, 좀 더 창조적이고 최상의 설계를 선택할 수 있도록 도움을 주는 것이다.(중략)

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.463-465
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• 2003

CDN (Content Delivery Network) [1]은 분배서버와 네트워크의 상태를 고려하여 다양한 서비스의 컨텐츠를 보다 효율적으로 전송할 수 있도록 설계된 네트워크이다. 이러한 CDN을 구성하기 위해서는 네트워크 계획, 컨텐츠 할당, 분배서버 선택 등을 고려해야 한다. 특히, 분배서버 선택을 위한 기존의 연구들은 분배서버 선택 시 모든 분배서버에 대한 측정된 값 (응답시간, 지연)이나 실시간 정보를 기준으로 분배서버를 선택하게 되므로 호 봉쇄 확률을 고려하지 않게 되고 제어 프로토콜로 인한 오버헤드가 많아지게 된다. 이를 해결하기 위하여 본 논문에서는 분배서버에서 서비스하고 있는 호의 수와 응답 시간을 고려한 새로운 서버 선택 알고리즘을 제안한다. 제안된 알고리즘에서 CDN의 분배서버들은 호의 수에 따라 논리적 최소 힙(heap) 구조로 구성되며 이를 이용하여 각 호스트는 자신에게 적당한 분배서버들의 서브 집합을 구성함으로써 오버헤드를 줄일 수 있는 메커니즘을 제안한다.