• Journal of the Korean Society for Heat Treatment
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• v.35 no.5
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• pp.255-261
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• 2022

In this work, the strain-amplitude independent and strain-amplitude dependent damping capacities of Mg-5%Sn alloy have been investigated as a function of its age-hardening response. The hardness increased with an increase in aging time, reached a peak value after 48 h, and then it gradually decreased. The damping capacities of the Mg-5%Sn alloy exhibited a decreasing tendency in the order of solution-treated, under-aged, peakaged, and over-aged states in the strain-amplitude dependent region, whereas they increased continuously with aging time in the strain-amplitude independent region. The microstructural examination during aging revealed that the lower concentration of Sn solutes in the α-(Mg) matrix and the lower density of the Mg₂Sn precipitate particles may well be the crucial factors for better damping values in the strain-amplitude independent and strain-amplitude dependent regions, respectively.

• Applied Microscopy
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• v.28 no.1
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• pp.21-38
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• 1998

The present study was performed to determine the effect of cold stress on myocardium of aging rat. Control groups, which aged 6, 12 and 24 months, were compared with age-matched experimental groups that were exposed to moderate cold stress for a hours daily in a week at laboratory cold room $(4{\pm}1^{\circ}C)$. The histological, histochemical and ultrastructural changes of myocardium were observed. The results were summarized as follow: 1. Age-dependent histological change of control groups was observed the formation of contraction band in 24months aged group. The experimental groups submitted to cold stress showed a similar change pattern as seen in control groups. However, the degree of change in the experimental groups was significantly larger than that of control groups. In the 34 months aged group the formation of hypercontraction band was observed. 2. Regarding age-dependent histochemical changes of control groups, we observed the increase activities of PAS and Masson's trichrome. In experimental groups the activities of PAS and Masson's trichrome were also increased with age. Compare with control group, the activities of PAS was increased but the activities of Masson's trichrome was decreased. 3. Age-dependent ultrastructural changes on vacuolization, lysosome were observed. In control groups the structural changes occur at 12 months. The accumulation of lipofuscin, contraction band, hypercontraction band and a component of connective tissue were observed in 24 months. However, the degree of change in the experimental groups was significantly larger than that of control groups. In contract, the myelin body in intercalated discs was observed in 24 months of experimental groups.

• Journal of Korean Society for Quality Management
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• v.25 no.3
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• pp.86-95
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• 1997

This paper considers a repairable system, which is maintained preventively at periodic times and is minimally repaired at each failure. Most preventive maintenance policies for such repairable systems assume that the cost of minimal repair is constant regardless of its age at failure. However, it is more practical to consider the situations where the cost of minimal repair is dependent not only on its age at failue, but also on the number of preventive maintenance carried out prior to its failure. We consider the preventive maintenance carried out prior to its failure. We consider the preventive maintenance policy with age-dependent minimal repair cost. The optimal policies which minimize the expected cost rate over an infinite time span are discussed. We obtain the optimal period and number of preventive maintenance prior to replacement of the system.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.313-318
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• 2000

This paper was to investigate the effect of component material to cause drying shrinkage of concrete. The latin square method was used in analysis of experimental results. The experimental factor was W/C, W/A, F.M and the level was divided into four step and the be analyzed. Compressive strength was mainly dependent in W/C through 90% F-verification. Drying shrinkage was mainly dependent on W/C in warly age through the same method, but not in later age. S/A, F.M did not affect compressive strength and drying shrinkage of concrete in all age.

• Restorative Dentistry and Endodontics
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• v.45 no.2
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• pp.21.1-21.12
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• 2020

The aim of this article was to review age-dependent clinical recommendations for appropriate root canal instrumentation techniques. A comprehensive narrative review of canal morphology, the structural characteristics of dentin, and endodontic outcomes at different ages was undertaken instead of a systematic review. An electronic literature search was carried out, including the Medline (Ovid), PubMed, and Web of Science databases. The searches used controlled vocabulary and free-text terms, as follows: 'age-related root canal treatment,' 'age-related instrumentation,' 'age-related chemo-mechanical preparation,' 'age-related endodontic clinical recommendations,' 'root canal instrumentation at different ages,' 'geriatric root canal treatment,' and 'pediatric root canal treatment.' Due to the lack of literature with practical age-based clinical recommendations for an appropriate root canal instrumentation technique, a narrative review was conducted to suggest a clinical algorithm for choosing the most appropriate instrumentation technique during root canal treatment. Based on the evidence found through the narrative review, an age-related clinical algorithm for choosing appropriate instrumentation during root canal treatment was proposed. Age affects the morphology of the root canal system and the structural characteristics of dentin. The clinician's awareness of root canal morphology and dentin characteristics can influence the choice of instruments for root canal treatment.

• Journal of Korean Public Health Nursing
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• v.3 no.1
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• pp.5-17
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• 1989

The purpose of this study was to investigate the natural menopause age of middle-aged women in Korea and to analyse various factors affecting them. For the collection of date, 1,140 women aged between 45-54 were selected through stratified sampling technics in Seoul and at a rual area in Kyong KiProvince. They were interviewed from Nov. 1 through Dec. 31,1987 by use of questionnaires made after pilot study had been performed twice. Among them the final subjects for analysis were restricted to only those who had experienced menopause or irregular menstruation during the past one year, the number of which was total 410:206 in urban and 204 in rural area. For the analysis, menopause age was used as dependent variables while fertility variables, socio-economic variables, bio-physical varibles, and insight of life variables were classified as independent variables. Dependent variables such as menopause was tested and analysed by descriptive statistical methods(e.g., frequency, percentage, mean, $X^2-test.$ t-test, ANOVA). The relation between menopause age and independent variables was analysed by use of Pearson's correlation coefficients. For the analysis of various factors affecting menopause age, multiple stepwise regression method was used. The obtained results are summarized as follows: 1. The natural menopause age of Korean women were 47.2 mean age: it was 47.7 and 46.7 mean age in urban and rural area respectively, which revealed that the former was later then the latter by one year. And the recollective error on menopause starting age between the menopause group and the group who had experienced irregular menstruation during the past one year was 0.4-0.7 year. 2. The main factors affecting the menopause age were (1) the duration of marital life, (2) the duration of oral pill use, (3) insight of life and economic status, (4) educational background. (5) menarche, (6) usual menstruation amount, (7) electic charge. and (8) area. These factors. altogether, could explain $18.4\%$ of factors related with menopause, and they took the high percentage in the order mentioned.

• Journal of Korean Neurosurgical Society
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• v.52 no.5
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• pp.441-446
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• 2012

Objective : Shunt-dependent chronic hydrocephalus (SDCH) is known to be a major complication associated with aneurysmal subarachnoid hemorrhage (aSAH). Old age is known to be one of numerous factors related to the development of SDCH. This study investigated whether postoperative cisternal drainage affects the incidence of SDCH and clinical outcome in elderly patients with aSAH. Methods : Fifty-nine patients participated in this study. All patients underwent aneurysmal clipping with cisternal cerebrospinal fluid (CSF) drainage. Clinical variables relevant to the study included age, sex, location of ruptured aneurysm, CT finding and clinical state on admission, clinical outcome, and CSF drainage. We first divided patients into two groups according to age (<70 years of age and ${\geq}70$ years of age) and compared the two groups. Secondly, we analyzed variables to find factors associated with SDCH in both groups (<70 years of age and ${\geq}70$ years of age). Results : Of 59 patients, SDCH was observed in 20 patients (33.9 %), who underwent shunt placement for treatment of hydrocephalus. Forty seven percent of cases of acute hydrocephalus developed SDCH. In the elderly group (${\geq}70$ years of age), the duration and amount of CSF drainage did not affect the development of chronic hydrocephalus. Conclusion : In elderly patients, although the incidence of SDCH was significantly higher, clinical outcome was acceptable. The duration and the amount of cisternal drainage did not seem to be related to subsequent development of chronic hydrocephalus within elderly patients aged 70 or older.

• Journal of Acupuncture Research
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• v.19 no.3
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• pp.126-137
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• 2002

Objective : There is accumulating data that cardiovascular diseases, including hypertension, cerebro-vascular accident, coronary heart disease, relate to atherosclerotic changes. Increased serum levels of lipids could play a role in these circumstances. the SDPTG(the second derivative of photoplethysmogram waveform) is noninvasive methods for evaluating the pulse wave and is correlated with age and other risk factors for atherosclerosis. Methods : To study the effects of serum lipid levels on the SDPTG in the middle-age adults, data on serum lipid levels and the SDPTG were collected in 80 healthy middle age with varying serum lipid concentrations. Biological vascular age was assessed using the SDPTG. the SDPTG consists of an a, b, c, and d wave in systole and an e wave in diastole; an SDPTG aging index(Al) was calculated as (b-c-d-e)/a. Results : Serum triglyceride, total cholesterol, total lipid, phospholipid, HDL cholesterol levels were respectively and significantly correlated with SDPTG Al. Serum lipid levels and blood pressure are age-dependent and the SDPTG is blood pressure-dependent. Restricting analysis to age and blood pressure yield strong positive correlations between serum triglyceride, total lipid levels and SDPTG Al, but no correlations between serum total cholesterol, phospholipid levels and SDPTG Al. Conclusion : The results of this study suggest that preventive acupuncture programs or herbal medications for reducing serum lipid, especially triglyceride, levels in middle-age should include a evaluation of biological vascular aging with the second derivative of photoplethysmogram waveform.

• Korean Journal of Biological Psychiatry
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• v.24 no.4
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• pp.219-224
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• 2017

Objectives This study sought to investigate the relationship between age, sex and alterations in levels of % carbohydrate-deficient transferrin (%CDT) and gamma-glutamyl transferase (GGT) in patients admitted with alcohol dependence. Methods The study retrospectively enrolled 187 patients who were diagnosed with alcohol dependence according to the Diagnostic and Statistical Manual of Mental Disorders-Fourth edition (DSM-IV) and were admitted into a closed ward in Hallym University Hangang Sacred Heart Hospital from 2009 to 2012 and Hallym University Kangnam Sacred Heart Hospital from 2012 to 2017. Demographic factors (age, sex) and biochemical markers [%CDT, GGT, mean corpuscular volume (MCV), aspartate transferase (AST), alanine transferase (ALT)] were collected by reviewing medical records. Alterations in the levels of %CDT and GGT in different groups for each demographic factor were compared after correcting for confounding variables (age, initial %CDT, GGT, MCV, AST, ALT). Results Decreased %CDT and GGT were observed during the period of abstinence after admission. The normalization period for %CDT increased with age, while the normalization period for GGT was longer in female patients. Conclusions These results suggest that alcohol-dependent patients that vary in age have different alterations in %CDT, while different sexes have different alterations in GGT. Age and sex can be potential indicators of treatment response after abstinence in patients with alcohol dependence. Further studies are needed to evaluate the relationship between these factors with regards to physiological and hematological changes in alcohol dependence.

• The Research Journal of the Costume Culture
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• v.17 no.1
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• pp.1-14
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• 2009

The purpose of this study was to examine consumers' brand attachment of fashion luxury product by emotional approach of brand loyalty. The questionnaire developed through the literature search and a survey was conducted both in on-line and off-line questionnaire simultaneously. Finally, 218 data from women who had a buying experience of fashion luxury products were analyzed using frequency, factor analysis, ANOVA, t-test, regression analysis by SPSS for WIN program. The results were as follows; First, there were significant differences in brand loyalty according to consumers' age, marriage yes or no, occupation, education level, and income. Second, the consumers' brand attachment of fashion luxury products was composed of five factors; emotional, dependent, attractive, knowledge, interest. Third, there were significant differences in brand loyalty according to consumers' age, marriage yes or no, occupation, education level, and income. Fourth, there were significant differences in brand attachment according to consumers' age, marriage yes or no, occupation, education level, and income. There were significant differences in emotional, dependent, attractive, knowledge, interest dimension of brand attachment according to consumers' age, sex, marriage yes or no, occupation, education level, and income. Fifth, the brand attachment significantly influenced on the brand loyalty.