• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.393-398
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• 2021

In order to optimize the performance of a lithium-ion battery, a performance prediction modeling technique that considers various degradation factors is required. In this work, mathematical modeling was carried-out to predict the change in discharging behavior and cycle life, taking into account the cycle aging of lithium-ion batteries. In order to validate the modeling, a cycling test was performed at the charge/discharge rate of 0.25C, and discharging behavior was measured through RPT (Reference Performance Test) performed at 30 cycle intervals. The accuracy of cycle life prediction was improved by considering the break-in mechanism, one of the phenomena occurring in the BOL (beginning of life), in the model for predicting the cycle life of lithium-ion batteries. The predicted change in cycle life based on the model was in good agreement with the experimental results.

• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.93-103
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• 2011

Precipitation behavior of high-nitrogen duplex Fe-24Cr-7Mn-4Ni-4Mo-0.43N stainless steel aged at $850^{\circ}C$ was investigated using scanning transmission electron microscopy. Based on the analyses of selected area diffraction patterns, four kinds of precipitates (intermetallic sigma (${\sigma}$) and chi (${\chi}$), $Cr_2N$ and secondary austenite) were identified. At the ferrite/austenite phase boundary, the ${\sigma}$ phase and secondary austenite were formed via ${\alpha}{\rightarrow}{\gamma}+{\sigma}$ eutectoid reaction. The precipitation of $Cr_2N$ occurred at the austenite grain boundary as well as the interior of the ferrite. The intermetallic ${\chi}$ phase also formed within the ferrite and showed a cube-cube orientation relationship with the ferrite. Further aging produced a lamellar structure composed of $Cr_2N$ and austenite along the ferrite/austenite boundary and enhanced the precipitation of the ${\chi}$ phase. The crystallographic features of the precipitates were also examined in terms of the orientation relationship with the austenite or ferrite matrix.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.477-481
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• 2008

The secondary hardening and fracture behavior in P/M high speed steels bearing V content of 9 to 10 wt% have been investigated in terms of austenitizing temperature and precipitation behavior. Austenitizing was conducted at 1,100 and $1,175^{\circ}C$ of relatively low and high temperatures. Coarse primary carbides retained after austenitization were mainly V-rich MC type. They give a significant influence on hardeness and toughness, as well as wear resistance. Tempering was performed in the range of $500{\sim}600^{\circ}C$. The peak hardness resulting from the precipitation of the fine MC secondary carbides was observed near 520, irrespective of austenitizing temperature. Aging acceleration(or deceleration) did not occur with increasing austenitizing temperature because it mainly influences contents of V and C of matrix through the dissloution of coarse primary MC containing lots of V and C. The precipitation of secondary MC carbides, which also contain V and C, did not change the aging kinetics itself. In the 10V alloy containing much higher C content, the impact toughness was lower than 9V alloy, because of the larger amount of primary carbide and high hardness.

• Food Science and Biotechnology
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• v.15 no.5
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• pp.721-727
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• 2006

This study was carried out to investigate the effect of hydrocolloids on the changes in physical properties of a model ice cream. The model ice cream contained water, sugar, skin milk powder, com oil, and 4 different hydrocolloid stabilizers (gelatin, pectin, hydroxyethylstarch, locust bean gum), was manufactured in a batch type freezer. The following physical characteristics of ice cream were examined: flow behavior, overrun, air cell size, ice crystal size, and melt resistance. With regard to flow behavior, all of aged mixes had a lower apparent viscosity relative to the mix before aging, and ice cream mix containing locust bean gum had the highest viscosity. Air cell size was observed to range from 20 to $38\;{\mu}m$, and ice cream with locust bean gum showed the largest size. There was an inverse correlation between overrun and air cell size. The ice crystal sizes of all samples ranged from 25 to $35\;{\mu}m$. Ice cream with added pectin contained the smallest ice crystal size, which was significantly difference from other stabilizers (p<0.05), and resulted in superior melt resistance with increased melting time compared to other samples.

• Health Policy and Management
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• v.23 no.2
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• pp.162-175
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• 2013

Background: The purpose of this study was to analyze the association between social support, psychosocial factors, and health behaviors of old adults in korean society. Methods: The data which was used in this study was extracted from the second wave of the Korean longitudinal study of aging in 2008. A total of 3,978 elderly aged 65 years or older were included in this study. We conducted $X^2$-test, t-test for the elderly health behavior in accordance with their social support and psychosocial factors. Also, multivariate logistic regressive analysis was performed in order to find how degree social support and psychosocial factors are associated with health behavior after adjusting sex, age, smoking (alcohol drinking), and other significant variables. The data was processed by SAS ver. 9.1 and Stata SE ver. 11. Results: Social support in older adults was significantly associated with lower smoking, alcohol drinking, exercise, and eating habit. Also, psychosocial factors were positively associated with smoking, alcohol drinking, regular exercise, and eating habit. Conclusion: health behaviors of old adults are likely to be vulnerable to social support and psychosocial factors. To increase effectiveness of the health policy for the elderly in Korea, it is important to adapt new strategy to include the empowerment of elderly's social networks, policy support to enhance subjective expectation, and life satisfaction.

• Journal of Korean Association for Spatial Structures
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• v.16 no.1
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• pp.35-42
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• 2016

Until recently, almost all ETFE film structures that have been erected is the cushion type because there are problems at lower allowable strength under elastic range and viscosity behaviour such as creep and relaxation of ETFE films under long-term stresses. But the number of tension type structures is currently increasing. This paper proposes the stretch fabrication of ETFE film to verify the applicability of ETFE films to tensile membrane structures. First of all, to investigate the possibility of application on tensile membrane structures, the stretch fabrication test is carried out, and it is verified that it is possible to increase the yield strength of the film membrane structures. After simulating the experiment also carries out an analytical investigation, and the effectiveness of the elasto-plastic analysis considering the viscous behavior of the film is investigated. Finally, post-aging tension measurement is conducted at the experimental facilities, and the viscosity behavior resulting from relaxation is investigated with respect to tensile membrane structures.

• Transactions of the Korean Society of Mechanical Engineers
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• v.4 no.4
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• pp.152-159
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• 1980

The temperature and the grain boundary precipitation have the great influence on the low-cycle fatigue behavior of austenite stainless steel at elevated temperature. For the purpose of investigating the mechanism concerning the change of fatigue micro crack mode in SUS 316 under various conditions low-cycle fatigue test was carried out at the elevated temperature 600.deg.C, plastic strain range 2% and constant strain rate .5c.p.m. A special attention is given to the observation of intergranular crack initiation. The results obtained are summarized as follows. The low-cycle fatigue behavior of SUS 316 at 600.deg.C is affected by transition of crack initiation mode from intergranular to transgranular. The transition is due to the aging effect, which is caused by grain boundary precipitations of Cr$\_$23/C$\_$6/. Since the intergranular crack initiation is brought about by the grain boundary sliding, the transgranular crack initiates in case that the strengthening of grain boundary due to the precipitation of Cr$\_$23/C$\_$6/ carbides takes place ahead of the intergranular crack initiation.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.6
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• pp.845-852
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• 2010

This study examined the recognition and purchasing behavior about environment-friendly agricultural produce (EFAP) of housewives in Yeungnam area. The data were collected from 401 housewives by a self-administered questionnaire on April, 2010. Frequencies, t test, chi-square test, and logistic regression analysis were conducted by SPSS Windows V.17.0. The results of the survey were as follows: (1) the purchase group of EFAP showed higher degree of concern about health and recognition about EFAP than the non-purchase group, (2) knowledge scores about EFAP were very low for both the purchase and non-purchase groups, (3) levels of confidence in EFAP in the purchase group were higher than those in the non-purchase group, (4) the purchase group considered high price as the main distribution problem about EFAP, whereas the non-purchase group regarded low trust toward producers, and (5) monthly household income (below 2,000,000 won) and confidence in EFAP were the significant factors affecting EFAP.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.167-174
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• 2010

In this paper, the ultraviolet rays images and aging judgement caused by surface contamination on 22.9[kV] class insulators was defined. UV images represented by the corona discharge are divided 3 types such as sunflower, jellyfish, amoeba and in detail, there are classified the progress mechanism of eight. In the field which is installed the power facilities, immediately, this judgement method can be found out the deteriorated parts of the power facilities. These steps are possible to judge the deterioration of power facilities through reliable data. Hereafter, this study as the diagnostic technology suitable for the sites is used.

• Journal of Family Resource Management and Policy Review
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• v.15 no.2
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• pp.1-21
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• 2011

Housing selections of the elderly depends on various changing factors as they get old. Among those factors, housing satisfaction might be one of the most predictable and crucial factor. This study is focused on the casual effect of housing satisfaction on the elderly's likelihood of selection among three alternatives of housing type. The sample was selected from 349 elderly aged above 65 who were living in Jeonju area, and was analyzed from multiple regressions and casual analysis. The results could be summarized as follows; First, the elderly preferred 'their own house living at present (aging in place)' among three housing type. Second, factors that influenced on housing satisfaction of the elderly were condition of health, economic status, living with spouse or not, level of social activities, and family supports. Third, the elderly who were male, without spouse living in single-family houses, in better health condition and with lower educational level were having more likelihood of selection of present housing. The elderly who were having more likelihood to select reverse mortgage payment were male, with spouse, living in apartment houses, the older, in worse health conditions and economic status. And the elderly who were male, with spouse, living in apartment houses, and in worse health conditions were having more likelihood to select national rental housing.