• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.4
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• pp.41-52
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• 2008

Ubiquitous service environment is poor in reliability of connection and has a high probability that the intrusion and the system failure may occur. Therefore, in the environment, the capability of a system to collectively accomplish its mission in spite of active intrusions and various failure scenarios, that is, the survivability of services are needed. In this paper, we analyze the Jgroup/ARM framework that was developed in order to help the development of fault- tolerant Jini services. More importantly, we propose an intrusion-tolerant Jini service architecture to satisfy the security availability and quality of services on the basis of the analysis. The proposed architecture is able to protect a Jini system not only from faults such as network partitioning or server crash, but also from attacks exploiting flaws. It is designed to provides performance enough to show a low response latency so as to support seamless service usage. Through the experiment on a test-bed, we have confirmed that the architecture is able to provide high security and availability at the level that degraded services quality is ignorable.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11B
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• pp.1685-1695
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• 2010

In this paper, we propose a new reliable multicast MAC protocol over the IEEE 802.11-based tactical ad hoc networks. The major contribution compared to the previous reliable multicast schemes using consecutive CTSs/ACKs is that the proposed scheme can send multiple CTS/ACK messages concurrently assisted by MC-DS/CDMA mechanisms. When multiple receivers receive the RTS/DATA message from a sender, they respond with the CTS/ACK message spread with pre-assigned code in the same time interval. The proposed scheme can reduce the overhead of multiple CTSs/ACKs. It is also possible to alleviate the received signal strength at the enemy detector and thus it improves low probability of detection performance. Through simulations and analysis, the proposed scheme outperforms that of the multiple CTSs/ACks in terms of the throughput, transmission delay and low probability of detection.

• Journal of the Korea Society of Computer and Information
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• v.29 no.1
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• pp.131-138
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• 2024

The ability of Combat Management System(CMS) to respond quickly and accurately to threat to a naval vessel is directly related to the survivability and combat power of the vessel. However, current method for detecting enemy submarine periscope in CMS rely on manual and subjective method that require operators to manually verify and analyze information received from sensor. This delays the response time to the threat, making the vessel less viable. This paper introduces a periscope detection algorithm that classifies the plot information generated by High Resolution Range Profile(HRRP) into probability-based suspicion classes and dramatically reduces threat response time through classified notifications. Algorithm validation showed 133.3791 × 10⁶ times faster and 12.78%p higher detection rate than operator, confirming the potential for reduces threat response time to increase vessel survivability.

• Korea Real Estate Review
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• v.27 no.3
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• pp.103-118
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• 2017

Under the ownership pre-sale system in the South Korean apartment market, developers can sell apartment ownerships as soon as they start to construct an apartment complex. In the South Korean apartment market, people call this kind of ownership "Bun-yang right." There is a time difference between ownership sale and apartment completion under the ownership pre-sale system. The pre-completion apartment ownerships can be resold to third parties until the apartment complexes are completed, which is called "Geon-mae" of the Bun-yang right. Using survival analysis, this research analyzed the elapsed time between ownership purchase and resale to a third party using 48,316 apartment units nationwide in the 192 complexes supplied from 2000 to 2016. Specifically, this study analyzed the influence of the real estate policy, contract term, location, apartment complex, and unit characteristics on the elapsed time between ownership purchase and resale to a third party. The empirical analysis revealed that the real estate policy and contract term characteristics have a significant effect on the elapsed time between ownership purchase and resale to a third party. Also, this study confirmed that the product characteristics, such as the location and apartment complex and unit characteristics, have an influence on the elapsed time between ownership purchase and resale to a third party.

• Journal of Internet Computing and Services
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• v.13 no.4
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• pp.11-21
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• 2012

It is indispensable that aircrafts in electrical warfare settings endeavour to improve their survivability by selecting optimal countermeasures against threats. In this paper, we model the successful probabilities of aircraft survivability equipments that remove threats encountered, and also propose a framework for the aircrafts to autonomously decide their countermeasures. And then, we design the operational effectiveness of the aircraft survivability equipments, and quantitatively formulate the operational effectiveness into the form of reduction in lethality (RL). We actually show how the operational effectiveness can be computed in simulated example scenarios. To verify our framework proposed in this paper, we experimented with the successful probabilities of aircraft survivability equipments and the autonomous decision-making against threats in various electronic warfare settings. In the experiments, it turns out that our agents outperform the agents that randomly choose their countermeasures, which is 12% more efficient in their performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.730-742
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• 2014

In the case of On-demand routing protocol in cognitive radio ad-hoc networks, broadcasting of control packets may occur common control channel overload and packet collisions during the routing procedure. This situation is to increase the overhead of path finding and also limited to find the accurate and reliable path. Since reliable channel and path finding is restricted, path life time is shorten and path reliability is reduced. In this paper, we propose a new routing algorithm that reduces control channel overhead and increases path life time by considering the probability of appearance of primary user and channel status of neighbor nodes. Each node performs periodic local sensing to detect primary user signal and to derive primary user activity patterns. The probability of primary appearance on the current channel and the channel status can be obtained based on the periodic sensing. In addition, each node identifies the quality of the channel by message exchange through a common channel with neighbor nodes, then determines Link_Levels with neighbor nodes. In the proposed method, the Link Level condition reduces the number of control messages that are generated during the route discovery process. The proposed method can improve path life time by choosing a path through Path_Reliability in which stability and quality are weighted depending on the location. Through simulation, we show that our proposed algorithm reduces packet collisions and increases path life time in comparison with the traditional algorithm.

• The KIPS Transactions:PartC
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• v.17C no.1
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• pp.119-128
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• 2010

In the shipbuilding industry, due to the global trends where the number of IT (Information Technology) devices of a smart ship have been increased rapidly, the need to develop a new shipboard backbone network has recently emerged for integrating and managing the IT devices of a smart ship efficiently. A shipboard backbone network requires high survivability because it is constructed in automatic and unmanned smart ships where a failure of the backbone network can cause critical problems. The purpose of this paper thus is to study SAN (Ship Area Network) as a efficient shipboard backbone network, considering particularity of shipboard environment and requirement of high survivability. In order to do so, we designed a dual network topology that all network nodes, including the IT devices installed in a smart ship, are connected each other through dual paths, and reuding tht IT devices pnstalles supporices network survivability as well as t Iffic efficiency for the dual network topology. And then, we verified the performance of the suggested SAN by theoretical and practical analysis including the graph theory, the probability theory, implemental specifications, and computer simulations.

• Radiation Oncology Journal
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• v.25 no.1
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• pp.43-53
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• 2007

[ $\underline{Purpose}$ ]: To evaluate the relationship between the expression of EGFR, p53, Cox-2, Bcl-2 and the clinical parameters of NPC (nasopharyngeal carcinoma) patients treated with radiotherapy with/without chemotherapy, and to determine if these could be used as a biologic marker. $\underline{Materials\;and\;Methods}$: This study retrospectively examined 75 NPC patients who were pathologically diagnosed at St. Mary's Hospital and Kangnam St Mary's Hospital from March 1988 to August 2002 and treated with radiotherapy with/without chemotherapy. The levels of EGFR, p53, Cox-2, and Bcl-2 expression were determined immunohistochemically. The relationship between the levels of EGFR, p53, Cox-2 and Bcl-2 expression and the H- E staining findings including the WHO classification, TNM stage, tumor response to chemotherapy and radiotherapy, disease free survival (DFS), and overall survival (OS) was analyzed. $\underline{Results}$: At a median follow up of 50.8 months (range: $5.5{\sim}201$ months), the 3 years OS rate and PFS rate were 68.7% and 68.2%, respectively. The five year OS rate and PFS rate were 53.5% and 51.1%, respectively. The median OS duration and PFS duration were 85.5 months and 61.1 months, respectively. The WHO classification correlated with the complete response rate, lymph node metastasis and distant metastasis. The expression of p53 was associated with increased mitosis and poor overall survival. The expression of Bcl-2 correlated with the DFS and WHO classification. The expression of Cox-2 correlated with a poor overall survival and response rate in the lymph node. However, EGFR was not correlated with any factors. $\underline{Conclusion}$: These results suggest that the expression of p53, Cox-2, Bcl-2 plays role in predicting prognostic factors for NPC treated with radiotherapy with/without chemotherapy. However, further study on a larger number of patients will be needed to identify more useful biomarkers of NPC.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.2
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• pp.97-106
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• 2001

본 연구에서는 트러스 구조물의 이산최적설계를 위해 유전알고리즘(GA)을 적용하였다. 확률론적인 절차를 통해 설계에 필요한 초기 집단을 생성시킨 후, 설계를 개선시키기 위해서 자연선택 및 적자생존의 원리를 적용하였다. 다하중조건 하에서 트러스 구조물의 중량 최소화를 위해 응력 및 변위 제약을 고려하였다. 먼저, 이미 잘 알려진 트러스 구조물에 대해서 GA를 이용하여 얻은 최적해와 기존 문헌들에서 제시하고 있는 값들을 비교함으로써 GA의 신뢰성 및 적용성을 검증하였고, 이러한 신뢰성 검증을 바탕으로 사용성 있는 트러스 구조물의 이산최적설계를 위해 현재 생산중인 강재제원표로부터 부재가 선택되도록 하였다. 강재의 단면으로는 L형강을 사용하였으며, L형강의 강종은 9개의 강종들 (SS 400, SWS 400, SMA 41, SWS 490Y, SWS 520, SMA 50, SWS 570, SMA 58) 중에서 설계자에 의해 자유롭게 선택되도록 하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.3
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• pp.360-371
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• 1993

Flood search algorithm is known to be an effective routing mechanism for tactical application, since it provides high degree of survivability and robustness. But it is known that it has significant drawbacks with respect to the network efficiency [1]. We consider a tactical circuit-switched grid network with a maximum of four links and two priority classes of voice traffic, Using the minimum first-derivative length (MFDL) path, we improve the blocking probability performance of the circuit-switched network without increasing the call set-up time and processor loading of the algorithm.