• Land and Housing Review
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• v.13 no.2
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• pp.91-115
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• 2022

This study examines changes in business survival rates in a gentrified commercial district by comparing early movers with late entrants. Using the Hongik University Commerical District, or Hongdae, as a case study, we adopt discrete-time survival analysis to compare survival rates between businesses established before 2000 (early movers) and ones established after 2000 (late arrivers). We compare the business survival patterns in a gentrified commercial district (experimental group) to non-gentrified commercial districts (control group) in Mapogu. We examine a survival-rate difference between early movers and late arrivers by different industrial categories. We finally examine a survival-rate gap between franchise and non-franchised businesses. The results show that the early movers have lower survival rates than the late arrivers in the gentrified Hongdae area, whereas there is no significant difference in survival rates between the early movers and the late arrivers in Mapogu. The early movers in daily-life-supporting businesses in Mapogu have even higher survival rates than the late-arrivers. In addition, franchised businesses have higher survival rates than non-franchised stores both in Hongdae and Mapogu. The results provide statistical and comprehensive evidence of the displacement of early movers at a more rapid pace in gentrified areas than non-gentrified aveas, which has been an anecdotal narrative.

• International Journal of Highway Engineering
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• v.12 no.1
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• pp.61-69
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• 2010

In this paper, we present the methodology about an optimal probability distribution selection as well as survival rate estimation with the national highway database from 1999 to 2008. Probability paper methods are adopted to estimate the parameters of each hazard model. The goodness-of-fit test, such as the Anderson-Darling statistics, was performed. As a result, we found that Lognormal distributionan is an appropriate distribution of newly constructed sections as well as overlayed sections. We also ascertained that the results of survival rate for pavement life between the proposed method and observed data are similar. Such a selection methodology and measures based on reliability theory can provide useful information for maintenance plans in pavement management systems as long as additional life data on pavement sections are accumulated.

• The Korean Journal of Applied Statistics
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• v.11 no.1
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• pp.151-161
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• 1998

We study the bootstrap interval estimation for survival function in the Koziol-Green model. We construct the approximate bootstrap confidence intervals for survival function and prove the strong consistency for the bootstrap estimator of survival function. Finally we show that the approximate bootstrap confidence intervals are better in terms of coverage probability than confidence intervals based on asymptotic normal distribution and transformations of survival function via Monte Carlo simulation study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.6
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• pp.488-496
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• 2015

This paper proposes a framework to determine the routes of multiple unmanned aerial vehicles (UAVs) to conduct multiple tasks in different locations considering the survivability of the vehicles. The routing problem can be formulated as the vehicle routing problem (VRP) with different cost matrices representing the trade-off between the safety of the UAVs and the mission completion time. The threat level for a UAV at a certain location was modeled considering the detection probability and the shoot-down probability. The minimal-cost path connecting two locations considering the threat level and the flight distance was obtained using the Dijkstra algorithm in hexagonal cells. A case study for determining the optimal routes for a persistent multi-UAVs surveillance and reconnaissance missions given multiple enemy bases was conducted and its results were discussed.

• 한국벤처창업학회:학술대회논문집
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• 2016.04a
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• pp.232-234
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• 2016

본 연구의 목적은 사내교육이 직원들의 재직기간에 미치는 영향에 대한 연구로, 실제 사설경비업체의 데이터를 이용하여 생존분석방법으로 퇴직 확률을 추정함으로써 다양한 시사점을 제공해주고 있다. 결론적으로 사내교육에 참여한 직원들이 그렇지 않은 직원들에 비해 퇴직할 확률이 더 낮은 것으로 나타났다. 구체적으로 교육의 종류(직무교육과 마인드교육)에 따라 재직기간에 상이한 영향을 끼치며, 이를 바탕으로 회사는 장기적인 관점에서 적절한 사내교육 프로그램을 개발하여 직원을 교육시킴으로써 우수 인재의 경쟁사로의 이직을 방어할 수 있을 것이다.

• Industry Promotion Research
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• v.5 no.1
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• pp.1-11
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• 2020

The purpose of this study is to analyze the industrial accidents data with survival model. EDA approach is used to explore the relationship between two variables and among three variables for the past 10 years of industrial accidents data. Survival models are also tried. Survival curve drops more rapidly for the business with fewer employees as time goes by. Industrial accidents occur more often as the total number of industrial accidents gets larger and as the number of employees gets smaller. Agriculture, fishing and forestry have a higher level of industrial accidents than construction while service industry and 'transportation·storage and telecommunication' have a fewer number of industrial accidents than construction. Korea Safety and Health Agency's and Ministry of Employment and Labor's involvement were not effective but Civilian's was. Recurrent event data analysis reveals all most the same result as for non-recurrent data analysis.

• Korean Journal of Social Welfare
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• v.68 no.2
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• pp.107-130
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• 2016

This study is aimed at the exploratory research on the influence of the obligation of extension of the retirement age on the baby boom generation. The basic question of this study is about which of the baby boom generation can get how much benefit according as the extension of the retirement age becomes compulsory. The extension of the retirement age is the system that can be applied to regular full-time workers. Accordingly, this study is intending to analyze the characteristics of the workers having a high likelihood for benefits from extension of the retirement age by tracing the economic activity state and labor history of the baby boomers. For this purpose, this study looked into the change of the economic activity state by age cohort of the male baby boomers based on the data for the Korea Labor Panel's 4th(2001) & 17th(2014)year. Using Survival analysis, this study also analyzed who will continue to remain as a regular full-time wage earner. As the result of the analysis, it was found that the more the cohort ages of baby boomers increased, the smaller the probability of remaining as a regular full-time wage earner, and the group who can get benefits from extension of the retirement age was predicted to account for only 11.4% level among the baby boomers. In addition, the result showed that there was a high likelihood of getting more benefits from extension of the retirement age when the baby boomers worked for the government-invested institution, corporate bodies, and government organizations rather than working for private enterprises. Thus, it can be safely said that there might appear a generational conflict due to extension of the retirement age in that such jobs coincide with the ones favored by the rising generation.

• The Korean Journal of Applied Statistics
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• v.35 no.1
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• pp.35-47
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• 2022

The receiver operating characteristic (ROC) curve was developed to quantify the classification ability of marker values (covariates) on the response variable and has been extended to survival data with diverse missing data structure. When survival data is understood as binary data (status of being alive or dead) at each time point, the ROC curve expressed at every time point results in time-dependent ROC curve and time-dependent area under curve (AUC). In particular, a follow-up study brings the change of cohort and incomplete data structures such as censoring and competing risk. In this paper, we review time-dependent ROC estimators under several contexts and perform simulation to check the performance of each estimators. We analyzed a dementia dataset to compare the prognostic power of markers.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.7
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• pp.535-539
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• 2007

We study an degree of alternativeness and a survivability of alternate routing algorithm in mobile ad-hoc tactical communication networks. The common channel signaling scheme is used and flood search routing algorithm is used for analysis. We also study a connectivity performance for flood search routing, restricted flooding and hybrid routing. From the results we expect low blocking probabilities with alternate routing and the conventional flood search routing shows better connectivity performance which results in high survivability.

• The Korean Journal of Applied Statistics
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• v.7 no.2
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• pp.53-77
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• 1994

In a certain stochastic process, Cox's regression model is used to analyze multistate survival data. From this model, the regression parameter vectors, survival functions, and the probability of being in response function are estimated based on multistate Cox's partial likelihood and nonparametric likelihood methods. The asymptotic properties of these estimators are described informally through the counting process approach. An example is given to likelihood the results in this paper.