• Korean Journal of Human Ecology
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• v.19 no.6
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• pp.1031-1044
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• 2010

Corresponding to the rapid growth of the aging population without an adequate social safety net for the elderly, older people face great disadvantages due to sudden illness or poor health and a lack of support from the younger generation. Furthermore, older women are suffering from a drastic deterioration of their economic status because of insufficient retirement savings. Examining the impact of labor force participation and living arrangement on health status and life satisfaction in later life, it is important to consider gender differences in context of social policies for the elderly. Using data based on a stratified national sample of the elderly by the Korean Longitudinal Study of Aging (KLoSA), multiple regression model were used to estimate the relationships between labor force participation and health status and subjective life satisfaction concerning the quality of their later life. The result indicates that good health status and high level of life satisfaction are associated with the type of paid work status for the elderly men, but those are associated with the type of non paid work, such as family businesses employees for the elderly women. Significant differences in chronic health condition and subjective life satisfaction by employment characteristics are found among the elderly. In addition, older women's high level of life satisfaction was associated with the participation of the social activity. The major conclusion from these results should help us understand gender differences in the elderly and acknowledge further exploration of gender variations in these people's later life.

• Survey Research
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• v.12 no.2
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• pp.1-26
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• 2011

Mortality for oldest-old age (aged 80 or over) in Korea has never been studied mainly due to lack of data leaving its quality aside. The rapid aging recently occurring in Korea, which no other country has never experienced, must introduce a drastic change in the structure of future population pyramid, requring a careful investigation on mortality level, pattern, and trend for the oldest-old age in Korea. For mortality trend, we need to extend the past mortality data, which has provided only an open-ended age interval 80 or 85 years and over, to age-specific mortality up to 115 years old. A prerequisite for such an extension is constructing a Korean standard mortality by which one can figure out the mortality level and pattern of the oldest-old age. A Korean standard mortality is proposed by applying one relational model and eleven functions from which we select best models for each sex in terms of three measures of fits and three consistencies of mortality. Then we extend the mortality of the open-ended age intervals by providing a method to avoid the longitudinal consistency of mortality.

• Journal of the Korea Society of Computer and Information
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• v.12 no.5
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• pp.203-214
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• 2007

The global mobile Internet service market is growing very rapidly, shooing drastic increases in its sales volume. Despite this growth of the market, it has not yet reached its full-grown stage, and this calls for a study on the service preference based on the characteristics of the users. As most of the existing studies in this area have centered on its technical features, they fall short of providing to the related companies any useful data to which they can practically refer in developing the future mobile services that suit for various user needs, and making plans to increase the sales volume. Based on these circumstances, this study is to investigate how the mobile contents preference is differed in accordance with the user characteristics of the Korean and Chinese mobile Internet service users. This study is also to analyze how the relationship between the user characteristics and the preferred mobile contents types is moderated by nations, Korea and Chinese. To accomplish these research purposes, this study developed a set of research model and hypotheses based on a comprehensive review of the related studies. To prove the research hypotheses, this study conducted a survey among the Korean and Chinese nubile Internet service users and performed a variety of analyses of the data collected including the questionnaires, using the SAS version 9.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.1
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• pp.58-66
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• 2014

Numerical simulations for the flows containing free surface remain difficult problems because the drastic differences of physical properties of water and air, The difference of densities makes the solution instable in particular. For the stabilities of the solutions, the most typical methods to simulate free surface flows, such as Volume Of Fluid(VOF) and Level-Set(LS) methods, impose transient zones where the physical prosperities are continuously distributed. The thickness of the transient zone is the source of the numerical errors. The other side, marker-density method does not use such a transient zone. In the traditional marker-density method, however, the air velocities of free surface cells are extrapolated from the water velocity, and the pressures on the free surface are extrapolated from the air pressures for the stability of the solution. In this study, the marker-density method is modified for the decrease of such numerical errors. That is, the pressure on the free surface is determined to coincide with the pressure gradient terms of the governing equations, and the velocity of free surface cells are calculated with the governing equations. Two-dimensional steady spilling breakers behind of a submersed hydrofoil and three-dimensional spilling breaker near a wedge shaped ship model are simulated using INHAWAVE-II including the modified marker-density(MMD) method. The results are compared with the results of Fluent V6.3 including VOF method and several published research results.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.129-134
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• 2007

In 1996, GS E&C became the first in the industry to adopt a Project Management System using EVM(Earned Value Management) to link schedule with profit/loss. In 2006, the TPMS(Total Project Management System) was completed by adding the concept of Lean Construction and JIT(Just In Time) to the Project Management System. This was done with the purpose of reducing waste and creating optimal work processes. This has been implemented on all sites and has enabled drastic increase of productivity. The portal provides customized information to the client, inspector and subcontractor personnel. Since various parties are receiving information that suits their requirements and is easy to use, usage has increased and since they are on the same platform, quick decisions and information sharing is possible. The purpose of the PMIS's success model in construction projects, this paper tests and proves the TPMS's efficiency and productivity to Dongnam Distribution Complex project.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.231-231
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• 2015

Rapid development in the upper reaches of the Mekong River, in the form of construction of large hydropower dams and reservoirs, large irrigation schemes, and rapid urban development, is putting water resources under stress. Many scientific reports have pointed out that cascade dams along the Mekong River lead to serious problems: not only hydrologically but also a decline of agricultural productivity due to a decrease of sediment supply in the Mekong Delta and a change of fish amount due to drastic change of the water environment. Cambodia and Vietnam, located in the lowest Mekong basin, are gravely affected by radical changes of hydrologic regime due to Mekong River developments. In particular, the Tonle Sap Lake in Cambodia is very sensitive to the flood cycle and flow variation of the Mekong River as well as inflow water quality from the Mekong River. More than 50% of Cambodian GDP depends on the primary industries such as agriculture, fishing, and forestry, and the Tonle Sap Lake plays an important role to support the national economy in Cambodia. In addition, Cambodian people usually take nourishment from the fish of Tonle Sap Lake. This research aims to assess the impacts of the Mekong river flow alternation on the hydrologic regime of the Mekong River - Tonle Sap Lake. We carried out rainfall-runoff-inundation simulation using CAESER-LISFLOOD for integrated water resource management in the Tonle Sap Basin and then analyze flood inundation variation of the Tonle Sap Lake due to the scenarios. Furthermore, the simulated inundation maps were compared to MODIS satellite images for model verification and hydrologic prediction.

• Computers and Concrete
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• v.27 no.4
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• pp.355-367
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• 2021

This paper investigates the mechanical response of simply supported one-way reinforced concrete slabs under fire through numerical analysis. The numerical model is constructed using the software ABAQUS, and verified by experimental results. Generally, mechanical response of the slab can be divided into four stages, accompanied with drastic stress redistribution. In the first stage, the bottom of the slab is under tension and the top is under compression. In the second stage, stress at bottom of the slab becomes compression due to thermal expansion, with the tension zone at the mid-span section moving up along the thickness of the slab. In the third stage, compression stress at bottom of the slab starts to decrease with the deflection of the slab increasing significantly. In the fourth stage, the bottom of the slab is under tension again, eventually leading to cracking of the slab. Parametric studies were further performed to investigate the effects of load ratio, thickness of protective layer, width-span ratio and slab thickness on the performance of the slab. Results show that increasing the thickness of the slab or reducing the load ratio can significantly postpone the time that deflection of the slab reaches span/20 under fire. It is also worth noting that slabs with the span ratio of 1:1 reached a deflection of span/20 22 min less than those of 1:3. The thickness of protective layer has little effect on performance of the slab until it reaches a deflection of span/20, but its effect becomes obvious in the late stages of fire.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.8
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• pp.1205-1212
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• 2022

Cyber threat targeting ICS (Industrial Control System) has indicated drastic increases over the past decade and Cyber Incident in Critical Infrastructure such as Energy, Gas Terminal and Petrochemical industries can lead to disaster-level accidents including casualties and large-scale fires. In order to effectively respond to cyber attacks targeting ICS, a multi-layered defense-in-depth strategy considering Control System Architecture is necessary. In particular, the centralized security log system integrating OT (Operational Technology) and IT (Information Technology) plays an important role in the ICS incident response plan. The paper suggests the way of implementing centralized security log system that collects security events and logs using OPC Protocol from Level 0 to Level 5 based on IEC62443 Purdue Model to integrate ICS security logs with SIEM (Security Information Event Management) operated in IT environment.

• Journal of Distribution Science
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• v.11 no.10
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• pp.73-79
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• 2013

Purpose - This study examines the impact of oil price volatility on economic activities in Korea. The new millennium has seen a deregulation in the crude oil market, which invited immense capital inflow into Korea. It has also raised oil price levels and volatility. Drawing on the recent theoretical literature that emphasizes the role of volatility, this paper attends to the asymmetric changes in economic growth in response to the oil price movement. This study further examines several key macroeconomic variables, such as interest rate, production, and inflation. We come to the conclusion that oil price volatility can, in some part, explain the structural changes. Research design, data, and methodology - We use two methodological frameworks in this study. First, in regards to the oil price uncertainty, we use an Exponential-GARCH (Exponential Generalized Autoregressive Conditional Heteroskedasticity: EGARCH) model estimate to elucidate the asymmetric effect of oil price shock on the conditional oil price volatility. Second, along with the estimation of the conditional volatility by the EGARCH model, we use the estimates in a VECM (Vector Error Correction Model). The study thus examines the dynamic impacts of oil price volatility on industrial production, price levels, and monetary policy responses. We also approximate the monetary policy function by the yield of monetary stabilization bond. The data collected for the study ranges from 1990: M1 to 2013: M7. In the VECM analysis section, the time span is split into two sub-periods; one from 1990 to 1999, and another from 2000 to 2013, due to the U.S. CFTC (Commodity Futures Trading Commission) deregulation on the crude oil futures that became effective in 2000. This paper intends to probe the relationship between oil price uncertainty and macroeconomic variables since the structural change in the oil market became effective. Results and Conclusions - The dynamic impulse response functions obtained from the VECM show a prolonged dampening effect of oil price volatility shock on the industrial production across all sub-periods. We also find that inflation measured by CPI rises by one standard deviation shock in response to oil price uncertainty, and lasts for the ensuing period. In addition, the impulse response functions allude that South Korea practices an expansionary monetary policy in response to oil price shocks, which stems from oil price uncertainty. Moreover, a comparison of the results of the dynamic impulse response functions from the two sub-periods suggests that the dynamic relationships have strengthened since 2000. Specifically, the results are most drastic in terms of industrial production; the impact of oil price volatility shocks has more than doubled from the year 2000 onwards. These results again indicate that the relationships between crude oil price uncertainty and Korean macroeconomic activities have been strengthened since the year2000, which resulted in a structural change in the crude oil market due to the deregulation of the crude oil futures.

• Membrane Journal
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• v.10 no.3
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• pp.139-147
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• 2000

Non-Fickian (or anomalous) diffusion was observed in transient sorption of aromatic solvents(such as benzene, toluene, and chlorobenzene) in fluoropolymers (such as ETFE, ECTFE and PVDF). In this study, five other transient sorption models (Crank, Long ＆ Richman, Berens ＆ Hopfenberg, Neogi, Li) based on Fick's law were employed to fit the anomalous sorption data for aromatic solvents. The adjustable parameters were determined by least square analysis of the measured and predicted fractional uptake. For ETFE sorption data slightly deviating from Fickian behavior, all the models exhibited satisfactory results in fitting the anomalous sorption data. In particular, Neogj model predicted intrinsic diffusivity (0.4～0.8$\times$10$^{-5}$ $\textrm{cm}^2$/day) and equilibrium diffusivity (0.13～0.31$\times$10$^{-4}$ $\textrm{cm}^2$/day) as well as relaxation kinetics related to non-Fickain diffusion. For a typical sigmoidal sorption behavior in PVDF, only Crank's model could give the reasonable evaluation on transport properties. The ratio of intial diffusivity (D$_{i}$) to final equilibrium diffusivity (D$_{\infty}$) was ranged from 80 to 200. For the final stage of uptake In ECTFE with drastic acceleration, all the models exhibited significant deviations from the sorption data. New diffusion models based on thermodynamics and continuum mechanics should be employed to get valuable information on transport properties as well as relaxation kinetics coupled with non-Fickian diffusion.