• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1529-1539
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• 2013

Recent case studies in Japan have shown that rockbolts are commonly installed at an oblique angle to the excavation direction of the tunnel, instead of at a right angle, due to restriction of the working space. In particular, in the case of expansion in an existing tunnel, the working space can be very small, due to the large protective structures necessary to operate within an existing tunnel. In this case, where both the current use of the existing tunnel, and the reinforcement of the ground around the tunnel are required, the effects of installation angles and patterns of rockbolts are important factors in the design process. Therefore, in this study, a total number of 24 model tests are performed, to investigate the reinforcing effects of system bolting installed obliquely from the excavation direction of the tunnel, by changing the installation angle of bolts, longitudinal distance, and bonded length of bolts. The model test results indicate that the relaxed load ratio decreases, with the increase of both the bonded lengths and the number of the installed bolts, resulting in the decrease of the supported area by one bolt. Two-dimensional numerical analysis, which considered the reinforcement effect of inclined system bolting as the change of engineering properties near the tunnel, demonstrated that the deflection patterns at the tunnel crown in the numerical simulations, show a similar tendency to those measured in the model tests.

• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.3
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• pp.399-407
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• 2012

To evaluate age and gender differences in the relation of cardiovascular risk factors, cognitive impairment, and subclinical carotid atherosclerosis from aged people using by a cross sectional method. Sixty-nine healthy elders living in the community who had not previously undergone carotid ultrasonography were included. We conducted life style surveys, and cognitive function tests including Korean-mini-mental state examination (K-MMSE) and clinical dementia rating-Korean. Various biomarkers from blood were assessed; fasting insulin-like growth factor-1, lipid-profile, high sensitivity C-reactive protein, total homocysteine, glucose, insulin, Homeostasis model assessment (HOMA) for insulin resistance index, vitamin B12, and folate level. Carotid intima-media thickness (C-IMT), and plaques were measured using carotid ultrasonography and aortic ultrasonography, a valid index of atherosclerosis. For the elderly subjects (aged 65-82 years), cognition impairment was more prevalent in females while subclinical atherosclerosis was more prevalentin males. Increased C-IMT has been kept in males, and C-IMT shows increasing trend and the peak at about 80 year-old in females with increasing age. The significant correlations between C-IMT and many vascular risk factors including age, triglyceride, abnormal homocysteinein male, and K-MMSE, insulin, HOMA index and abnormal aortic ultrasonography in female were different in each gender, with the exception of homocysteine (p<0.05). This data suggests that there were differences of age and gender characteristics in terms of subclinical atherosclerosis, cognitive impairment and vascular risk factors in community-living elders. Further larger and longitudinal studies across entire age are required to better understand the effects of risk factors on subclinical atherosclerosis.

• Korea journal of population studies
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• v.24 no.2
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• pp.79-115
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• 2001

This research explores determinants of induced abortion in Korea. Data from the 1997 Korea National Fertility Survey by Korea Institute of Health and Social Affairs are used for this research. Another aim of this study is to verify a methodological appropriateness of survival analysis in the study of determinants of induced abortion. I compare the result of survival analysis with that of logit analysis for this purpose. In this study, it is revealed that age at conception, number of children, and number of son that have been considered as determinants of induced abortion are still significant in determining induced abortion. However, unlike results of prior research, the practice of contraception does not affect the choice of induced abortion when I control for that the conception was wanted or not. I also find that there is a significant interaction between number of son at the time of conception and intention of the conception. Induced abortion has a far reaching impact on a society as well as on the health and well-being of a woman. In Korean society, sex-selective induced abortion with son preference can cause a very high level of imbalance of sex ratio at birth. Hence, it is so important to be more cautious to the practice and prevalence of induced abortion in the age of lowe fertility.

• Korea journal of population studies
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• v.25 no.2
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• pp.107-138
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• 2002

In general, women's labor force participation follows a M-curve pattern because women's state of economic activity usually changes by their life course stage. This research attentions that the effect of sequence of life course as well as the effects of‘marriage bar’, or‘maternity leave’is very important in understanding women's chaning economic activity status. First, this research hypothesizes that women's four patterns of job career such as‘continuous pattern’,‘discontinuous pattern’,‘non-economic activity pattern’,‘marriage leave pattern’result a significant difference in social and demographic variables. Second, this research analyzes the effect of ordering and timing of life events on women's work transition. This research investigates labor market dynamics to conceptualize labor market behaviors using longitudinal data and sequence analysis and event history analysis. We find that four patterns of job career vary by age, educational attainment, having a certificate or not, their parents’human capital and health status. And we find that the ordering and timing of‘participation in labor market’and‘marriage’determine the pattern of women's work transition.

• Korean Journal of Social Welfare
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• v.57 no.2
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• pp.351-374
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• 2005

This study examines dynamics of poverty in Korea, focusing on poverty duration and its determinants. Data come from Korean Labor and Income Panel Study(KLIPS), 1998-2003. KLIPS is a longitudinal survey of 5,000 families and their members which are representative of urban residents in Korea. Respondents of KLIPS annually report detailed information on their income, economic activities, and other socio-economic characteristics. This study use poverty exit probabilities to generate distributions of spell lengths, following Bane and Ellwood(1986)'s methodology. This study finds a high level of poverty exit rates in Korea. About three quarters of those beginning a poverty spell exit from poverty within two years. Only 14.3 percent of all the poverty spells consist of long spells which persists five years or more. Yet, a different picture emerges when spells of the poor persons at a given time are analysed. Persistent poor occupy a considerable share of all the poor. Almost 50 percent of those who would be in poverty at a given time are in the midst of poverty spells lasting five years or more. When repeat spells of poverty are also included in the analyses, the proportion of long-term poor increases further. 63 percent of persons poor at a given time are long-termers. The majority of long-term poor are members of families headed by the aged. They show both a low level of poverty exit rates and a high level of reentry rates, and thus are most likely to experience long-term poverty. In the first place, they occupy a substantial share of all the poor. The second who are likely to be poor longer is members of families headed by non-aged women. Researchers have recentlty paid much attention to the working poor who have increased since the economic crisis in 1997. Yet, it is very likely that families headed by non-aged male who largely consist of the working poor temporarily experience poverty. Findings for this study suggest that further studies and policy proposals addressing persistent poverty are necessary.

• Korean journal of communication and information
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• v.30
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• pp.35-87
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• 2005

This research explores the empirical confirmation of the Internet development including from the period of innovation to the time of social-cultural use in today. The research focused on how tradition news media rover about the Internet developed from early to today, and understanding the media characteristics on the each stages from news frame. The research Is designed to conduit content analysis from 1989 to 2004, then this research is divided four(4) stages of the Internet development: innovation, diffusion, commercial usage, social-cultural usage. The results shows that there are significant different coverage by the stages. First of all, the news coverage pattern shift from technology focused on early stages to social usage focused on the later stages. This research confirms that the ratio of the seriation(technology) coverage defined when social usage is increased, on the other hand skeumorphs(social usage and content) coverage is increased in the commercial and social usage stages. This coverage pattern among news media does not such a big different and there is no competitive coverage. Moreover, the news coverage shifted from thematic coverage on early stages to episodic coverage while the number of usage increasing. In addition, the tone of coverage has not been changed significantly.

• Journal of The Korean Association For Science Education
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• v.24 no.6
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• pp.1256-1271
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• 2004

The importance of science attitudes is more increasing in science education. Science attitudes may influence students' attainment, consistency and quality of classwork as well as their later views of science education and scientific occupations. According to the international comparative researches and longitudinal studies on Korean students' science attitudes, it has shown that the more grade, the less science attitude. This research was survey the science attitudes and learning environment variables, and then make a inquiry that causes of decline of science attitudes. To study this purpose, the participating students in this study will be selected from 3th to 11th grade. 6,925 participants were administered 3 times in questionnaires of science attitudes and learning environment variables during a year. The result of this study showed that science attitude got low after June. Science attitude was changed from 4th grade to 8th grade students. Science attitude much more decrease second semester than first semester, high school students' science attitude fell much. It was experience about science that cause the biggest effect in science attitude and other learning environment variables influence in science attitude change. Learning environment variables made different influence from students of increased and declined science attitude. As category that influence in science attitude, in elementary school were gender, area and grade, in middle school were grade and area, and in high school was area.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.1
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• pp.75-82
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• 2007

As one of the main support systems, rock bolts play a crucial role in the reinforcement of tunnels. Numerical and experimental studies using a transmission method of ultrasonic guided waves are performed to evaluate the integrity of rock bolts encapsulated by grouting paste. Numerical simulations using "DISPERSE" are carried out for the selection of the optimal experimental setup, i.e. non-destructive testing (NDT) system of the rock bolt. Based on results of the numerical simulation, the calculated frequency range for NDT testing is between 20kHz and 70kHz with the first longitudinal L(1) mode. Laboratory transmission tests are performed by attaching the piezo electric sensor at the tip of the rock bolt before embedding. Both of analytical and experimental results show that the amplitude of signals as well as the wave velocity increases with increase in the defect ratio of grouting paste. The defect in grouting paste means that the space around the rock bolt is not fully filled with the grouting paste. Experimental results also show that the increase of the wave velocity is more sensitive to the defect ratio increase than that of the amplitude. This study demonstrates that the transmission technique of ultrasonic guided waves may be a valuable tool in the evaluation of the rock bolt integrity.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.10
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• pp.4335-4338
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• 2015

Background: Oral cancer is the third most common malignancy in Saudi Arabia, the highest incidence of which is reported from Jazan province. The objective of this study was to evaluate the association of various locally used substances, especially shamma, with oral cancer in the Jazan region of Saudi Arabia. Materials and Methods: A hospital-based case-control study was designed and patient records were scanned for histologically confirmed oral cancer cases. Forty eight patients who were recently diagnosed with oral cancer were selected as cases. Two healthy controls were selected for each observed case and they were matched with age (+/- 5 years) gender and location. Use of different forms of tobacco such as cigarettes, pipe-smoking and shamma (smokeless-tobacco) was assessed. Khat, a commonly used chewing substance in the community was also included. Descriptive analysis was first performed followed by multiple logistic regression (with and without interaction) to derive odds ratios (ORs) and 95% confidence interval (CIs). Results: Mean age of the study sample (56% males and 44% females) was 65.3 years. Multinomial regression analysis revealed that shamma use increased the odds of developing oral cancer by 29 times (OR=29.3; 10.3-83.1). Cigarette (OR=6.74; 2.18-20.8) was also seen to have an effect. With the interaction model the odds ratio increased significantly for shamma users (OR=37.2; 12.3-113.2) and cigarette smokers (OR=10.5; 2.88-3.11). Khat was observed to have negative effect on the disease occurrence when used along with shamma (OR=0.01; 0.00 - 0.65). Conclusions: We conclude that shamma, a moist form of smokeless tobacco is a major threat for oral cancer occurrence in the Jazan region of Saudi Arabia. This study gives a direction to conduct further longitudinal studies in the region with increased sample size representing the population in order to provide more substantial evidence.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.691-694
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• 2014

Background: Tumor length in patients with esophageal cancer (EC) has recently received great attention. However, its prognostic role for EC is controversial. The purpose of our study was to characterize the prognostic value of tumor length in EC patients and offer the optimum cut-off point of tumor length by reliable statistical methods. Materials and Methods: A retrospective analysis was conducted on 71 consecutive patients with EC who underwent surgery. ROC curve analysis was used to determine the optimal cut-off point for tumor length, measured with a handheld ruler after formalin fixation. Correlations between tumor length and other factors were surveyed, and overall survival (OS) rates were compared between the two groups. Potential prognostic factors were evaluated by univariate Kaplan-Meier survival analysis. A P value less than 0.05 was considered significant. Results: There were a total of 71 patients, with a male/female divide of 43/28 and a median age of 59. Characteristics were as follows: squamous/adenocarcinoma, 65/6; median tumor length, 4 (0.9-10); cut-off point for tumor length, 4cm. Univariate analysis prognostic factors were tumor length and modality of therapy. One, three and five year OS rates were 84, 43 and 43% for tumors with ${\leq}4cm$ length, whereas the rates were 75, 9 and 0% for tumors >4 cm. There was a significant association between tumor length and age, sex, weight loss, tumor site, histology, T and N scores, differentiation, stage, modality of therapy and longitudinal margin involvement. Conclusions: Future studies for modification of the EC staging system might consider tumor length too as it is an important prognostic factor. Further assessment with larger prospective datasets and practical methods (such as endoscopy) is needed to establish an optimal cut-off point for tumor length.