• Journal of Labour Economics
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• v.35 no.1
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• pp.55-88
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• 2012

This article investigates the patterns of workforce aging in each industry, and examines how changing industrial structure affected the labor-market demand for and employment security of older workers in Korea. The relative size of the industries that are major employers of older workers has relatively declined since 2001, resulting in a decrease in labor-market demand for aged persons. Changes in industrial structure that occurred during the last decade have also brought an overall deterioration in the extent of employment security of older workers. These results suggest that the economic environment surrounding policies aimed at encouraging the employment of older workers is not entirely favorable. This paper also points out that policy makers need to consider that employment conditions of older workers are highly heterogenous across industries.

• KIEAE Journal
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• v.17 no.2
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• pp.5-12
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• 2017

Purpose: Under the purpose of presenting the adequate remodeling period for the improvement of thermal insulation performance of external walls in deteriorated buildings, the change in external wall and residential environment problem(dew condensation) due to aged deterioration after the apartments were constructed in Korea were analyzed. Method: Temperature Difference Ratio Outside(TDRo) and Heat Flow Meter(HFM) were used as measurement methods to evaluate the thermal insulation performance of deteriorated buildings. For TDR evaluation, thermo-graphic camera was used to measure and analyze the surface temperature of external wall. Also, dew condensation evaluation was analyzed using the Temperature Difference Ratio Inside(TDRi). Result: As a result of analyzing thermal performance through TDRo, the first decline point of thermal insulation performance began after 14-16 years have passed since construction was completed, and after 20 years have passed the decline point of thermal insulation performance reappeared. As a result of analyzing U-value with HFM measurement method, the decline rate of external wall's thermal insulation performance is lower than 2% in average at around 5 years after completion, and 8.7% in average at 10-15 years, and over 10.2% in average at 20 years.

• Physical Therapy Korea
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• v.12 no.2
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• pp.20-27
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• 2005

Osteoporosis is characterized by low bone mass and the microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture. It has been suggested that speed of sound (SOS) and broadband ultrasound attenuation (BUA) of quantitative ultrasound sonography (QUS) may provide information about not only bone density but also the microarchitecture and elastic properties of bone. Physical inactivity reduced mechanical usage and it made process to the bone changes. This study aimed to association between the physical activity and the QUS parameters in 1305 (593 men, 712 women) aged 20 years over in a rural population. Two QUS parameters, BUA (p=.23) and SOS(p=.73) were measured at the right calcaneus of postmenopausal women, no significant associations were observed between sports index and SOS and BUA. These results suggest that work, non-sports leisure physical activity (p<.01) have a significant influence on QUS parameters in a rural population. Physical activity are meaningful predictor of QUS parameters of the calcaneus in a rural population.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.857-868
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• 2005

This paper deals with the accumulated damage in concrete structures due to the cyclic freeze-thaw as an environmental load. The cyclic ice body nucleation and growth processes in porous systems are affected by the thermo-physical and mass transport properties, and gradients of temperature and chemical potentials. Furthermore, the diffusivity of deicing chemicals shows significantly higher value under cyclic freeze-thaw conditions. Consequently, the disintegration of concrete structures is aggravated at marine environments, higher altitudes, and northern areas. However, the properties of cyclic freeze-thaw with crack growth and diffusion of chloride ion effects are hard to be identified in tests, and there has been no analytic model for the combined degradations. The main objective is to determine the driving force and evaluate the reduced strength and stiffness by freeze-thaw. For the development of computational model of those coupled deterioration, micro-pore structure characterization, pore pressure based on the thermodynamic equilibrium, time and temperature dependent super-cooling with or without deicing salts, nonlinear-fracture constitutive relation for the evaluation of internal damage, and the effect of entrained air pores (EA) has been modeled numerically. As a result, the amount of ice volume with temperature dependent surface tensions, freezing pressure and resulting deformations, and cycle and temperature dependent pore volume has been calculated and compared with available test results. The developed computational program can be combined with DuCOM, which can calculate the early aged strength, heat of hydration, micro-pore volume, shrinkage, transportation of free water in concrete. Therefore, the developed model can be applied to evaluate those various practical degradation cases as well.

• New & Renewable Energy
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• v.7 no.2
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• pp.28-35
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• 2011

Recently, photovoltaic systems have been devolved into much larger systems up to MW-scale. Photovoltaic industry participants give their focus on power generation capability of photovoltaic modules because their benefits can be decided from the amount of generation. The information on long-term performance change of photovoltaic modules helps to estimate the amount of power generation and evaluate the economic cost-benefits. Long-term performance of a PV system has been analyzed with operation data for 12 years from 1999 to 2010. In the first year, the amount of yearly power generation was 57.7 MWh with 13.2% capacity factor. In 2007, the amount of yearly generation was 44.3 MWh with 10.14% capacity factor, and in 2010, the amount was decreased down to 38.1 MWh with 8.7% capacity factor. The result means that long-term capacity factor has been 4.5% decreased for 12 years and that the amount of generation has been decreased 34.0% for 12 years which is 2.8 % per year. The latter capacity factor has been decreased faster than 0.20%, the average rate for 10 years. The performance decrease of the PV system is meant to be accelerated. The decrease of performance and utilization is due to aged deterioration of photovoltaic modules and lowering conversion efficiency of PCS.

• Journal of Korean Public Health Nursing
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• v.31 no.2
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• pp.244-256
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• 2017

Purpose: This research was conducted to identify methods of inducing health promotion behavior, perceived health status, social participation and empowerment in the frail elderly receiving home visiting services. Methods: The subjects were 255 frail elders aged over 65 registered in the home visiting services of five public health centers in Daegu. Data were collected from June 9 to August 10, 2015. Data were analyzed by descriptive statistics, t-test, ANOVA, Scheffe's test and Pearson's correlation coefficient using SPSS Win 18.0. Results: The mean health promotion behavior, perceived health status, social participation and empowerment scores were 2.56 (${\pm}0.33$), 7.11 (${\pm}1.98$), 2.60 (${\pm}0.69$) and 2.90 (${\pm}0.29$), respectively. There was significant difference in health promotion behavior by client classification and life satisfaction. There were significant differences in perceived health status by life satisfaction, social participation by religion and client classification and empowerment by past jobs. Health promotion behavior, perceived health status, social participation and empowerment were positively correlated. Conclusion: An integrative health care program that includes these significant variables of subjects is essential to management and prevention of deterioration of frailty in elderly.

• Journal of the Ergonomics Society of Korea
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• v.35 no.5
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• pp.449-464
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• 2016

Objective: The objective of this study is to identify essential requirements of the instrument cluster's features and layout for elderly drivers through interview and paper prototyping. Background: Recent updates implemented in passenger vehicles require more complex information to be processed by drivers. Concurrently, a large portion of the US population, the baby boomer generation has aged, causing their physical and cognitive abilities to deter. Thus it is crucial that new methods be implemented into vehicle design in order to accommodate for the deterioration of mental and physical abilities. Method: Forty elderly drivers and twenty young drivers participated in this study. The test included three sessions including: 1) location value assessment to identify the priority of areas within the instrument cluster; 2) component value assessment to capture rankings of the degree of importance and frequency of use for possible instrument cluster components; and 3) paper prototyping to collect self-designed cluster with selection of designs for each component and location of features from each participant. Results: Results revealed differences in the area priority of the instrument cluster as well as the shape and location of component features for age and gender groups. Conclusion: The study provided insights on instrument cluster layout guidelines by proving elderly driver's mental model and preferred cluster design configurations to improve driving safety. Application: LCD-based vehicle instrument cluster design, with an adaptable feature configuration for cluster components and layouts.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.3
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• pp.98-105
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• 2011

Patterns and levels of aging vary between the book volume and sheets, even though both are made from the same paper materials. In case of book format, the outside is more easily affected than inner side by environmental factors such as temperature, humidity and air. In this study, the change in optical properties after dry heating accelerated aging was comparatively analyzed to understand the difference of the optical aging characteristics between outside and inner side of the duplicated beeswax-treated volume. It is found that the cover pages of the beeswax-treated volumes were more optically deteriorated than their middle pages. This indicates that outer sides of aging book volume directly exposed to the air is more vulnerable to serious deterioration than inner sides. Also, aromatic compounds such as benzoic acid and cinnamic acid were observed in the investigation of UV/VIS absorbance of the beeswax in each aged sample.

• Membrane and Water Treatment
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• v.8 no.2
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• pp.137-147
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• 2017

A water treatment utility in South Korea operates a large system of pressurized hollow fiber membrane (PHFM) modules. The optimal selection of membrane module for the full scale plant was critical issue and carried out using Risk-based Life Cycle Cost (RbLCC) analysis based on the historical data of operation and maintenance. The RbLCC analysis was used in the process of decision-making for replacing aged modules. The initial purchasing cost and the value at risk during operation were considered together. The failure of modules occurs stochastically depending on the physical deterioration with usage over time. The life span of module was used as a factor for the failure of Poisson's probability model, which was used to obtain the probability of failure during the operation. The RbLCC was calculated by combining the initial cost and the value at risk without its warranty term. Additionally, the properties of membrane were considered to select the optimum product. Results showed that the module's life span in the system was ten years (120 month) with safety factor. The optimum product was selected from six candidates membrane for a full scale water treatment facility. This method could be used to make the optimum and rational decision for the operation of membrane water purification facility.

• Journal of the Korean Solar Energy Society
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• v.39 no.2
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• pp.45-55
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• 2019

More than 76% of the detached houses in Korea are over 20 years old. These old detached houses have poor energy efficiency. According to the 2017 Housing Census (Statistics Korea), more than 50% of low-income families live in detached houses. Therefore, the improvement of energy efficiency in old detached houses is needed from the viewpoint of energy welfare. The general method of building energy modelling for the verification of energy efficiency is based on the construction year data of "Building Design Criteria for Energy Saving" due to the cost and time involved in collecting the thermal performance data of buildings. There is poor accuracy with the deterioration of long-term aging of building materials. Also, the selection of alternatives for energy performance improvement is based on the items to be applied, not a performance improvement goal. It is difficult to calculate energy performance that reflects variations in various parameters with dynamic energy simulations. In this study, the influence of long-term aging is used to accurately predict the energy performance of old detached houses. The building energy modelling method is called ENERGY#, which is a static analysis method based on ISO13790. Energy performance is evaluated by a combination of input variables including building orientation, insulation of walls and roof, thermal performance of windows and window/wall ratio, and infiltration rate. Finally, this study provides a way to determine alternatives that meet energy performance improvement goals.