• Journal of the military operations research society of Korea
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• v.22 no.2
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• pp.200-214
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• 1996

In this paper, the problem of determining the probability of kill(or survival) of a vulnerable target by one or more missiles is considered. The general formulas are obtained for the kill or survival probability the target is killed or survival. Several well-known concepts such as those of vulnerability, lethality, multi-component target, and a general combinatorial theorem of probability are introduced and used. For the convenience in this paper, the word missile is used in a very general sense and the target is generally taken to be a point target. And, this paper, is concentrated primarily with the probabilistic aspects of the problem, also a general numerical procedures are also described. Two examples are shown to illustrate the use of some of the formulas in this study, but also illustrate a few points which may not have been sufficiently emphasized. The extension study to complete a software package will be followed.

• Journal of Environmental Impact Assessment
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• v.18 no.5
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• pp.293-299
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• 2009

Wintering migratory species of white-fronted geese (Anser albifrons) are common visitor in South Korea, and this study examined the survivorship of white-fronted geese in the Junam Reservoir with the application of Population Viability Analysis (PVA) technique. In Junam PVA analysis was done for the next 50 years using factors of breeding population, sex ratios, survivorship in the VORTEX program. As a result white-fronted geese will reach to carrying capacity within 40 years, and population will reach to carrying capacity later when it becomes smaller. Also with a large initial population white-fronted geese will reach to carrying capacity earlier. In conclusion, for the next 50 years the white-fronted geese are expected to a long-term survival with stable condition with survivorship (0.03) and extinction rate (0.0).

• Journal of Chest Surgery
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• v.37 no.4
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• pp.328-334
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• 2004

There are only limited numbers of reports about long-term results of tricuspid valve replacement(TVR) with bioprosthetic and mechanical prostheses. We analyzed risk factors for tricuspid valve replacement and compared long-term clinical results of bioprosthetic and mechanical valves in tricuspid position. Material and Method: We reviewed 77 cases of TVR, which were performed between October 1978 and December 1996. Mean age was 38.8 15.9 years. Bioprostheses were implanted in 26 cases and mechanical prostheses were implanted in 51 cases. Result The operative mortality was 15.6% and late mortality was 12.3%. Survival for bioprosthetic and mechanical valve group at 5, 10 and 13 years was 81.3% vs. 100%, 66.1% vs. 100%, 60.6% vs. 100% (p=0.0175). Free from valve related re-operation for bioprosthetic and mechanical valve group at 5, 10 and 13 years was 100% vs. 93.9%, 100% vs. 93.9% and 58.3% vs. 93.9% (p=0.3274). Linealized incidences of valve related re-operation for bioprosthetic and mechanical valve group was 2.27 %/patient-years and 1.10 %/patient-years. Risk factor analysis showed that presence of preoperative ascites, hepatomegaly larger than 2 finger breaths, poor preoperative NYHA functional class and number of tricuspid valve replacement were risk factors for early mortality, and the use of bioprosthetic valve and number of open heart surgery were risk factors for late mortality. Conclusion: Long-term survival of mechanical valve was superior to bioprosthetic valve in tricuspid position. We recommend mechanical valve in tricuspid position if the patient can be closely followed up.

• Journal of Chest Surgery
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• v.33 no.7
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• pp.552-559
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• 2000

Background; The aim of this study is to evaluate our clinical experience with the Carbomedics heart valve prosthesis. Material and Method; Between Aug. 1988 and Dec. 1998, 294 Carbomidics valves were implanted in 235 patients(mitral; 143, mitral and aortic; 59, aortic; 33) The mean age at operation is 40.0$\pm$12.3 years(range 7 to 68 years); 63.8% (150patients) were woman. Follow up was 97.4% complete and mean follow up time was 5.7years with a total of 1209.2 patient-years. Result; The hospital mortality was 8.9%(mitral; was 95.2$\pm$1.6%(mitral ; 94.9$\pm$2.1%, mitral and aortic 95.0$\pm$3.7%, aortic 96.2$\pm$3.8%). Actual freedom rates from complications(linearized rates in parentheses) were fllowings; thromboembolism 96.2$\pm$1.5%(0.59%pt-yr), valve thrombosis 96.7$\pm$1.4%(0.5%/pt/yr), anticoagulant related hemorrhage 98.3$\pm$1.0%(0.25%/pt-yr), perivalvular leak 99.0$\pm$1.4%(0.5%/pt-yr), endocarditis 98.7$\pm$1.0%(0.25%/pt-yr), perivalvular leak 99.0$\pm$0.7%(0.17%pt-yr), endocarditis 98.7$\pm$1.0%(0.17%$\pm$pt-yr) and overall valve-related complications 88.9$\pm$2.5%(1.68%/pt-yr). Conclusion; The clinical performance of the Carbomedics valve was quite satisfactory with a low incidence of valve related mortality and morbidity.

• The Korean Journal of Applied Statistics
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• v.26 no.3
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• pp.531-547
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• 2013

Multiple life models are useful in multiple life insurance and multiple life annuities when the payment times of benets in these insurance products are contingent on the future life times of at least two people. A reverse mortgage is an annuity whose monthly payments terminate at the death time of the last survivor; however, actuaries have used female life table to calculate monthly payments of a reverse mortgage. This approach may overestimate monthly payments. This paper suggests a last-survivor life table rather than a female life table to avoid the overestimation of monthly payments. Next, this paper derives the distribution of the future life time of last survivor, and calculates the expected life times of male, female and last survivor. This paper calculates principal limits and monthly payments in cases of male life table, female life table and last-survivor life table, respectively. Some numerical examples are discussed.

• Korean Journal of Social Welfare Studies
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• v.42 no.1
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• pp.219-242
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• 2011

This study examined the factors associated with exit from and reentry into the rehabilitation center among homeless persons with mental illness. Shelter use of a total of 203 study population was monitored between 2004 and 2008. Cox's proportional hazard model was employed to analyze the factors influencing the rate of the first exit from and the first reentry into the rehabilitation center. Also, competing risk analysis was conducted to examine the factors differently associated with the type of the first exit from the rehabilitation center: a positive exit and a negative exit. This study found that homeless persons with mental illness were less likely to experience the negative exit while their resident registration status not being abolished on the first entry into the rehabilitation center, having more frequent hospitalizations during the rehabilitation center stay, being connected to the family members, having more participations into the basic rehabilitation, mental rehabilitation, and vocational rehabilitation programs during the rehabilitation center stay. Age, the number of hospitalization and of the participations into the mental rehabilitation programs during the rehabilitation center stay were associated with the rate of the first reentry into the rehabilitation center.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.71-79
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• 2011

Korean national highway has been increased 2 times more for the past ten years because of many highway geometric improvements and new routes since 2000. According to the reasons, maintenance cost has been increased continuously. Deterioration of concrete bridge decks caused by asphalt pavement deformation occupies a high proportion of overall bridge management budget. The number of current highway bridges has reached over 7,800 in 2011, and It is difficult to determine to some future budget. This study predicted the remaining life of concrete bridge decks using the reliability analysis based on Weibull distribution. and The expected future maintenance cost was estimated.

• Journal of IKEEE
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• v.11 no.4
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• pp.165-170
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• 2007

The main goal of research concerning clustering protocols is to minimize the energy consumption of each node and maximize the network lifetime of wireless sensor networks. However, most existing clustering protocols mainly focused on the design and formation of clusters, leaving the consideration of communication between the cluster head and the sink behind. In this paper, we propose efficient multi path routing algorithm by using MAC-NET Cross-layering. multi path needed only one tiny packet from sink to setup. In addition proposed algorithm can be used for any cluster-based hierarchical inter-clustering routing algorithm. The simulation results demonstrate that proposed algorithm extended the overall survival time of the network by reducing the load of cluster heads. The performance of proposed algorithm is less affected by the extension of sensing field than other inter-clustering operation.

• The KIPS Transactions:PartC
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• v.11C no.7 s.96
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• pp.923-930
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• 2004

Wireless sensor networks is a core technology of ubiquitous computing which enables the network to aware the different kind of context by integrating exiting wired/wireless infranet with various sensor devices and connecting collected environmental data with applications. However it needs an energy-efficient approach in network layer to maintain the dynamic ad hoc network and to maximize the network lifetime by using energy constrained node. Cluster-based data aggregation and routing are energy-efficient solution judging from architecture of sensor networks and characteristics of data. In this paper. we propose a new distributed clustering algorithm in using distance from the sink. This algorithm shows that it can balance energy dissipation among nodes while minimizing the overhead. We verify that our clustering is more en-ergy-efficient and thus prolongs the network lifetime in comparing our proposed clustering to existing probabilistic clustering for sensor network via simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2579-2586
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• 2014

It is crucial to set up early the required performance of surface ship for preventing the risk factors such as an excess of performance, cost and period in development stage. In this study, MOP and MOE are proposed to establish the method for deriving alternatives, MOP represents the defensive effect for anti ship missiles and MOE is the ratio of cost and performance. The 16 engagement scenarios which selectively install RF decoy, RF jammer, CIWS and anti air missile are suggested. The simulation results by using NORAM tool operated by ROK Navy show that the ship survivability is 0.605~0.975 and MOP is 0.301~0.887. The analyzed results represent the operating scenario with RF decoy, RF jammer and short range anti air missile is the best cost and effectiveness measure.