• Geotechnical Engineering
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• v.14 no.2
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• pp.21-30
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• 1998

The settlement characteristics of refuse landfills are peculiar because considerable amount of settlement occurs due to the decomposition of refuse organic solids for very long period. The total amount of compression that occurs due to the decomposition in refuse landfill is mainly dependent on the amount of biodegradable refuse solids and fill Ige of the refuse landfill, and the settlement stabilization speed is dependent on the decomposition condition. In order to figure out the settlement characteristics of refuse landfills. a proposed mathematical model is applied to settlement data of refuse landfills with different fill ages. A data bank of model parameters was obtained and the trends were analyzed. The long-term settlement behavior of refuse landfills can be estimated fairly well by the proposed model. The total remaining amount of settlement may be predicted on the basis of the fill age and appropriate two design parameters.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.130-135
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• 1998

This paper presents results of research performed to identify optimum mix proportions for production of flowable fill with high volume fly ash content. The fly ash used in this study met the requirements of KS L 5405 and ASTM C 618 for Class F material. Tests were carried out on concrete designed to have 10 ~ 15kg/$\textrm{cm}^2$ compressive strength at the 28-day age with fly ash contents of approximately 280kg/㎥. Slump was held at 25$\pm$1cm for all mixtures produced compressive strengths at 28 days were found to range from 5.03 to 13.69kg/$\textrm{cm}^2$.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.854-859
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• 2008

This study describes the aging behavior of soils and its mechanism, which have been reported in the literatures mainly by Mitchell(1986) and Schmertmann(1991). It could be known that aging of soils has both positive and negative effects on mechanical properties of soils. In order to show aging effects on dam behavior, a parametric study was carried out based considering the presence of a weak area within clay core zone of the fill dam. From the comparison of results obtained from numerical analysis and filed investigation, age-softening phenomena occurred within core zone during about 30 years after its completion.

• Journal of Periodontal and Implant Science
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• v.38 no.3
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• pp.429-436
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• 2008

Purpose: The goal of periodontal regenerative therapy is to replace bone, cementum, and periodontal ligament on a previously diseased root surface, which has suffered the loss of these supporting structures. To accomplish the regeneration, a number of surgical procedures have been advocated throughout the years. There seems to be a potential for some spontaneous periodontal tissue regeneration in the bottom of periodontal defect following open flap debridement alone. The aim of this study was to analyse the radiographic bone changes over 2-year after flap operation. Material and Methods: Patients attending the department of periodontics of Kyungpook National University Hospital were studied. Patients had clinical and radiographic evidence of infrabony defect(s). forty two sites of 33 patients aged 26 to 65 (mean age 45.5) were treated by flap operation with or without osseous surgery. Baseline and over 2-year follow-up radiographs were collected and evaluated for this study. Radiographic assessment includes a bone fill, bone crest change, defect resolution, and % of defect resolution. Pre- and post-treatment differences between variables (maxilla and mandible, gender, defect depth, defect angle) using the paired t-test were examined. Result: We observed 0.74 mm of bone fill, 0.66 mm of crestal resorption, 1.40 mm of defect resolution, and 27% of percentage of defect resolution. Mandible, women, deeper initial defect depth, narrower initial defect angle showed greater bone fill, defect resolution, and % of defect resolution. Conclusion: The results of this study suggest that the use of flap operation did enhance the outcome in terms of radiographically detectable bone fill. Both treatment resulted in some loss of crestal bone height.

• The Journal of Engineering Geology
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• v.26 no.2
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• pp.207-221
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• 2016

As greater numbers of fill dams and reservoirs become old, the risks of damage or embankment collapse increases. However, few studies have considered the deterioration and hazard classification of the internal core layers of fill dams. This study reports the results of geotechnical investigations of 13 earth-cored fill dams in Korea, based on no-water borehole drilling, Standard Penetration Test, and 2D and 3D electrical resistivity surveys along with in situ and laboratory testing. High-capacity no-water boring minimized core layer disturbance while providing continuous core sample recovery. The results allow the classification of potential hazards related to the existing core layers based on both visual inspection of the recovered samples and the results of engineering surveys and tests. Four types of potential hazard are classified: locally fluidized core with a high water content, rapid water inflow to a borehole, cores with granular materials, and relatively low stiffness of core. Among these, the locally fluidized core is the most critical hazard that requires remedial action because it is related to the potential internal flow path and internal erosion. The other three hazard types are of medium importance and require careful monitoring and regular inspection. Of note, there was no correlation between age and core deterioration. The results are expected to aid the safe management and potential upgrading of aging cored fill dams.

• Journal of the Korean Home Economics Association
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• v.41 no.1
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• pp.213-229
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• 2003

The purpose of this study is to examine the heath status and health behavior of middle-aged Korean men and women. Even though there has been increased concern about extremely high mortality rate of Korean middle-aged men and mental health problems of middle aged women, there is a dearth of empirical studies which examine the health status and health behavior of middle-aged men and women in Korea. This study attempts to fill these gaps. Data gathered from 1,667 men and women aged between 30-59 are analyzed to examine the level of physical health, mental health, perceived health and health behavior and to explore the gender and age group differences in these aspects. The results show that there exist gender difference and age group difference in health status: Women are less healthy than men and as age increased health status declined. Women at their 50s are least healthy and most unhappy suggesting age and gender interaction in health status. There exist a gender difference in health behavior: Men have regular check-ups more frequently than women and exercise more. These results are discussed in terms of the gender differences in the experiences, social roles and life styles over the life course.

• Journal of the Korean Geotechnical Society
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• v.16 no.2
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• pp.41-50
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• 2000

본 연구에서는 여러 침하모델들을 매립경과기간이 다른 아홉 개 지역의 실제 스레기 매립지 침하자료들에 적용하였다. 침하모델들을 적용한 결과, 매립연한이 증가할수록 향후 발생가능한 장기침하량도 상당히 감소하는 경향을 보였다. 신선한 쓰레기 매립지에서는 침하모델들마다 예측정도에서 큰 차이를 보이지만, 매립연한이 오래된 매립지들에서는 Power creep law를 제외하고는 예측정도에 있어서 큰 차이를 보이지 않음을 알 수 있었다.

• Journal of the Korean GEO-environmental Society
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• v.11 no.6
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• pp.85-91
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• 2010

As enormous construction projects of land development are carried out around Korea, useful construction materials are needed to perform the construction projects. However, there are no more enough of fill and reclamation materials in our country. That is why the coal ash is expected to be utilized as an alternative material. Since the coal ash has the characteristics of a pozzolan and a selfhardening material, it is adjudged that coal ash has a great possibility to be used as a fill and reclamation material. In this study, grain size analysis, Atterberg limit test, and specific gravity test were performed to examine the physical characteristics of the coal ash about a self-hardening material before utilizing the coal ash in the construction. Compaction test, unconfined compression test, direct shear test, and flexible wall permeability test were conducted to investigate the engineering characteristics according to mixture ratios of fly ash and bottom ash. As a result of the tests, it was confirmed that the mixing ratio 1:1 of fly ash and bottom ash is the most effective to use as a fill and reclamation material. If the mixture of coal ash is used as a backfill material with light weight around structure, it is expected to play a significant role in reducing earth pressure on the back of the structure. As the age of the mixture of coal ash goes by, it intends to decrease the coefficient of permeability. As described above, the coal ash should be considered as an alternative material of fill and reclamation materials since the result of the tests indicates that the coal ash is suitable to a useful material on the construction design.

• Journal of Technologic Dentistry
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• v.38 no.4
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• pp.315-325
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• 2016

Purpose: This study investigated perception and plan of dental technologists regarding the old age and retirement for them to enjoy stable old age. Methods: Dental technologists working in Seoul, Incheon, and Gyeonggido were asked to fill out a self-administered questionnaire, and a total of 200 copies were used for analysis. The collected data were statistically analyzed by using SPSS 22.0(Statistical Package for Social Sciences. Chicago, IL, USA) (a=0.05). In order to compare perception toward old age preparation among the subjects, a Chi-square test was performed, and, to investigate the level of preparedness for old age according to general characteristics, t-test was performed. Results: In the analysis of the old age preparedness by age, there was a significant difference in financial preparation, Asset identification, use of retiring allowance, information gathering, senior town home, and stability (p<0.05). To the questions regarding perception toward retirement, the majority of the subjects (60.5%) answered they had thought about retirement, and many (23.9%) of them attributed the reason to job stress (23.9%). Regarding old age preparedness according to workplace, there was a significant difference in use of retirement allowance and education for old age preparedness between general dental laboratories and general hospitals (p<0.05). Conclusion: It is believed that, for preparation of dental technologists for stable old age, in addition to their personal effort, it is important to provide social support and practical measures to ensure welfare and retirement.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3469-3476
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• 2016

Background: The cancer research literature suggests that women, especially premenopausal women, have lower cancer mortality rates than men. However, it is unclear if that is true for populations at all age levels in all countries and what factors affect such sex differences. This paper attempts to fill that gap. Materials and Methods: Sex- and country-specific cancer mortality data were statistically analyzed with particular attention to geographic, social, and economic factors that may affect the sex differences. Results: The sex differences were age and country specific, rather than universal. Premenopausal women actually tend to have a disadvantage compared to men or postmenopausal women. Male cancer mortality appears to be the affecting factor in explaining variations in sex differences. Latitude of residence and literacy rate are the affecting factors in cancer mortality and sex differences. African and Latin American countries tend to have a female disadvantage, while East Asian and Eastern European countries are more likely to have a female advantage. Conclusions: The findings challenge the cancer mortality literature and indicate that the sex differences and their possible causes are more complicated than the current literature suggests. They also highlight the urgency of adapting age- and country- specific health systems and policies to better meet the needs of younger women.