• Progress in Medical Physics
• /
• v.10 no.1
• /
• pp.23-32
• /
• 1999

Combined MRI and Relaxogram approach was introduced as a very useful tool for fat study. The phantoms simulating homogeneous mixture of fat and non-fat environments were measured with spin echo pulse sequence on a 0.15 T whole body imager. From 45 scans, the Tl values were obtained by fitting the data to continuous distribution (CONTIN) of relaxation time. This relaxogram gives broad distributions of relaxation time, which are characterized by a number of peaks with characteristic T1 values. Two distinct peaks in relaxogram were observed and identified as signals from com oil and gelatin gel. This model system can be served as simulating the distribution of fat in muscle. Also the relative ratio of two components, which is proportional to the area under the peak, is estimated and compared to nominal values. Based on the good agreement between two predictions, the values from our proposed method agreed with nominal values within $\pm$7 % error. The effects of different concentration of contrast agent and different region of interest are presented. To optimize total scan times, the minimum required data points and so further reduction in total scan times are discussed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.9
• /
• pp.161-169
• /
• 2020

This study investigated the effects and relationships of various stress, school life adjustment and happiness factors among middle school and high school adolescents. The structural model group effects between boy and girl groups were also investigated. Data was employed from the 'Korean Children and Youth Well-Being Index Survey, 2018' while subjects of the analysis included 5,144 students. Based on the education statistics data, the sample was collected by probability proportional to size. Results utilizing structural equation modeling and multigroup analysis showed that first, school stress, friend stress, and look stress had significant effects on adolescent happiness. School life adjustment had positive significant effects on adolescents' happiness. Parent stress, money stress and school stress had significant effects on school life adjustment. Second, the mediating effect of school life adjustment between stress and happiness was significant with parent, school stress, and financial stress. Third, results of the multi-group analysis by level and gender showed that the structure was similar between boys and girls, with the only differences among mediating effects. Boys had significant mediating effects by school stress, and financial stress, while girls had significant mediating effects by school stress, financial stress, and parent stress. Finally, based on the results of the study, practice and policy implications were suggested to support the promotion of adolescents' happiness.

• Toxicological Research
• /
• v.20 no.2
• /
• pp.89-100
• /
• 2004

The comet assay (also called the single-cell gel electrophoresis assay) has been widely used for detecting DNA damage and repair in individual cells. Since the conventional methods of evaluating comet assay data using frequency statistics are unsatisfactory we developed a new quantitative measure of DNA damage/repair that is based on all information residing in the dose/time-response curves of a comet experiment. Blood samples were taken from 25 breast cancer patients before undergoing radiotherapy. The comet assay was performed under alkaline conditions using isolated lymphocytes. Tail DNA, tail length, tail moment and tail inertia of the comet were measured for each patient at four doses of $\gamma$-rays (0, 2, 4 and 8 Gy) and at four time points after irradiation (0, 10, 20 and 30 min) using 100 cells each. The resulting three-dimensional dose-time response surface was modeled by multiple regression, and the second derivative, termed 2D, on dose and time was determined. A software module was programmed in SAS/AF to compute 2D values. We applied the new method successfully to data obtained from cancer patients to be assessed for their radiation sensitivity. We computed the 2D values for the four damage measures, i.e., tail moment, tail length, tail DNA and tail inertia, and examined the pairwise correlation coefficients of 2D both on the log scale and the unlogged scale. 2D values based on tail moment and tail DNA showed a high correlation and, therefore, these two damage measures can be used interchangeably as far as DNA repair is concerned. 2D values based on tail inertia have a correlation profile different from the other 2D values which may reflect different facets of DNA damage/repair. Using the dose-time response surface, other statistical models, e.g., the proportional hazards model, become applicable for data analysis. The 2D approach can be applied to all DNA repair measures, Le., tail moment, tail length, tail DNA and tail inertia, and appears to be superior to conventional evaluation methods as it integrates all data of the dose/time-response curves of a comet assay.

• Journal of Preventive Medicine and Public Health
• /
• v.28 no.1 s.49
• /
• pp.207-223
• /
• 1995

A new medical delivery system which regulated outpatient department(OPD) use from tertiary care hospitals was adopted in 1989. Under the new system, patients using tertiary care hospital OPD without referral slip from clinics or hospitals could not get any insurance benefit for the services received from the tertiary care hospital. This study was conducted to evaluate the Patient Referral System(PRS) with respect to health care expenditures and utilization. Two data sets were used in this study. One was monthly data set(from January 1986 to December 1992) from the Annual Report of Korea Medical Insurance Corporation(KMIC). The other was monthly joint data set composed of personal data of which 10% were selected randomly with their utilization data of KMIC from January 1988 to December 1992. The data were analyzed by time-series intervention model of SAS-ETS. The results of this study were as follows: 1. There was no statistically significant changes in per capita expenditures following PRS. 2. Utilization episodes per capita was increased statistically significantly after implementation of PRS. The use of clinics and hospitals increased significantly, whereas in tertiary care hospitals the use decreased significantly immediately after implementation of PRS and increased afterwards. 3. Follow-up visits per episode were decreased statistically significantly after implementation of PRS. The decrease of follow-up visits per episode were remarkable in clinics and hospitals, whereas in tertiary care hospitals it was increased significantly after implementation of PRS. 4. There was no statistically significant changes in prescribing days per episode following PRS. Futhermore, clinics and hospitals showed a statistically significant decrease in prescribing days per episode, whereas in tertiary care hospital it showed statistically significant increase after implementation of PRS. 5. Except high income class, the use of tertiary care hospitals showed statistically significant decrease after implementation of PRS. The degree of decrease in the use of tertiary care hospitals was inversely proportional to income. These results suggest that the PRS policy was not efficient because per capita expenditures did not decrease, and was not effective because utilization episodes per capita, follow-up visits per episode. and prescribing days per episode were not predictable and failed to show proper utilization. It was somewhat positive that utilization episodes per capita were decreased temporarily in tertiary care hospitals. And PRS policy was not appropriate because utilization episodes per capita was different among income groups. In conclusion, the PRS should be revised for initial goal attainment of cost containment and proper health care utilization.

• Journal of Preventive Medicine and Public Health
• /
• v.40 no.6
• /
• pp.467-474
• /
• 2007

Objectives : Gastric cancer is the most common incident cancer in Korea. Although Helicobacter pylori infection is the most important risk factor for the development of gastric cancer, cigarette smoking has also been suggested to play an important role in the development of gastric cancer. The objective of this study is to evaluate the relationship between cigarette smoking and gastric cancer risk in a Korean population. Methods : The study population consisted of 13,785 subjects who had been enrolled in the Korean Multi-Center Career Cohort between 1993 and 2002. As of December 2002, 139 incident gastric cancer cases were ascertained through the Korea Central Cancer Registry and the National Death Certificate Database. Relative risks (RR) and 95% confidence intervals (CI) for gastric cancer were estimated using Cox#s proportional hazard model adjusted for age, education, alcohol drinking status and history of gastritis or ulcer. Results : Significant dose-response relationships were observed between the duration of smoking and the risk of gastric cancer among the male subjects in comparison to non-smokers: men who smoked for 20-39 years had a 2.09-fold (95% CI 1.00-4.38) increase, and those who smoked for more than 40 years had a 3.13-fold (95% CI 1.59-6.17) increase in the risk of gastric cancer ($P_{trend}<0.01$). Conclusions : This study suggests that a longer duration of cigarette smoking may increase the risk of gastric cancer development in a dose-response manner in Korean men. The association between smoking and gastric cancer risk in women should be verified in future studies with a larger number of cases.

• Therapeutic Science for Rehabilitation
• /
• v.9 no.4
• /
• pp.33-43
• /
• 2020

Objective: This study used a mixed methods analytical approach to analyze the level of depression in and quality of life of patients who had been exposure to Agent Orange. Methods: Data on the general characteristics, depression level, and the quality of life of 29 patients who were hospitalized because of exposure to Agent Orange were collected. Focus group interviews were conducted with 17 of these 29 patients. Regarding mixed methods, the sequential integrated design model proposed by Teddlie and Tashakkori (2003) was employed. The analytical methods were as follows: (1) general characteristics were examined using frequencies and proportional distributions; (2) depression scores and quality of life scores were assessed using descriptive statistical analysis; and (3) content analysis was used to examine the focus group interview data. Results: The average K-GDS depression score was 19.24 points, and the average WHOQOL-BREF quality of life score was 57.66 points. The focus group interview data yielded 3 topics were named "deployment route", "the manner of exposure to Agent Orange", and "life after Agent Orange exposure". Conclusion: There is an urgent need to increase public awareness, develop a public policy response, and conduct additional research on ground occupational therapy programs that include physical therapy.

• Journal of the Korean Regional Science Association
• /
• v.11 no.1
• /
• pp.79-91
• /
• 1995

As an exit to solve the economic depression of the development countries in the early twentieth century, the 'old international division of labor' developed. The economic crisis(i.e., under-consumption crisis) was due to the absence of the mode of regulation compatible with the extensive regime of accumulation(i.e., "Fordist" regime). The crisis was solved by the state intervention through the creation on institutions in order to increase the level of consumption. Until the late 1960s when "high Fordism" reached(i.e., a harmonious relation between the monopoly mode of regulation and the intensive accumulation of capital), the developed core countries enjoyed a remarkable economic growth. The external market was not a necessity for the economic growth because there were increases in labor productivity and proportional increases in real wages and thus increases in consumption level. In the 1970s, however, the core faced with economic crisis again. Due to the breakdown of the postwar "Fordist" regime of capital accumulation and the post 1973 world depression, the core needed the Third World as a solution for their internal and international economic crisis. Thus the 'new international division of labor'(NIDL) arose. The "Fordist" method of production(i.e., the divisions of production process) led to the territorial division of labor and to the detailed division of labor. The aim of the NIDL is to exploit reserve armies of labor on a world scale and thus to reduce production costs. According to the NIDL model, the Third World countries have been developing by the core countries' investment on mainly labor-intensive industries and thus have been playing an important role in the global economy. And the NIDL theorists argue that multinational corporations have increasingly invested in the Third World nations and contributed to the economic growth in those regions. Tables presented in the paper show that the global trend since the 1970s does not follow the argument exactly as the NIDL theorists predicted. On the contrary, the core countries focus on developing technology, adopting the automation of production process, and trading within the core countries rather than on investing in the periopheral countries. The continuing investment of multinational corporations into the periphery is not because of cheap labor force but because of the market potentials in the regions. Majority of corporations of the core tries to reduce production costs by investing in technological development more intensively and also by changing regional strategies (i.E., investment from metropolitan areas to medium - or small - size cities, focusing on agglomeration economy, boosting regional diversification, etc.) within their own countries. The main purpose of the paper is to review and to criticize the NIDL theory based on some empirical data.IDL theory based on some empirical data.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.5
• /
• pp.2219-2231
• /
• 2012

This study conducted to investigate incidence rate and association of serum lipid profiles with incidence of ischemic heart disease. Study subjects consisted of 417,642 adults aged 30 years and over, who underwent physical examination and responded to questionnaire from health examination center of 19 university general hospitals. Hazard ratio of risk factor for ischemic heart disease (IHD) were calculated by Cox's proportional hazard regression model adjusted for ages, BMI and lifestyle (drinking, smoking and exercising). For TC/HDL ratio, hazard ratio of IHD in male increased from 1.21 times to 1.84 times increase with TC/HDL ratio, and that in female also increased from 1.26 times to 1.86 times. For TG/HDL ratio, hazard ratio of IHD in male increased from 1.17 times to 1.49 times increase with TG/HDL ratio, and that in female also increased from 1.42 times to 1.97 times. For LDL/HDL ratio, hazard ratio of IHD in male increased from 1.26 times to 1.82 times increase with LDL/HDL ratio, and that in female also increased from 1.26 times to 1.68 times. In conclusion serum lipid indexes are the significant risk factors for cardiovascular diseases. The higher the concentration of TC, LDL and TG is, the lower the concentration of HDL is, hazard ratio for IHD increased. Ratio of TC/HDL, TG/HDL and LDL/HDL were also verified to be significant risk factors for IHD.

• Journal of the Korean Society for Railway
• /
• v.17 no.4
• /
• pp.270-280
• /
• 2014

In this study, to examine the causes of cracks in continuously reinforced concrete tracks (CRCTs) and the main factors affecting cracking, a field survey on the status of cracks and crack patterns in the Gyeong-bu high speed line was conducted, and the crack patterns of CRCT due to the temperature difference between the top of the slab (TCL) and the bottom of the subbase (HSB) and the drying shrinkage of concrete were predicted by a nonlinear finite element model considering the structure of CRCT. The results of the numerical analysis show that cracks will be developed at the interface between the sleeper and the TCL, and under the sleeper due to the temperature difference and concrete shrinkage. This corresponds well to the crack locations found in the field. Also, it is found that the most significant factors are the coefficient of thermal expansion with respect to the temperature difference, and the drying shrinkage strain with respect to shrinkage. According to the results, the reinforcement ratio should be carefully determined considering the structures of CRCT because the crack spacing is not always proportional to the reinforcement ratio due to the sleepers embedded in the TCL.

• Journal of Preventive Medicine and Public Health
• /
• v.45 no.6
• /
• pp.394-401
• /
• 2012

Objectives: Diabetes and obesity each increases mortality, but recent papers have shown that lean Asian persons were at greater risk for mortality than were obese persons. The objective of this study is to determine whether an interaction exists between body mass index (BMI) and diabetes, which can modify the risk of death by cardiovascular disease (CVD). Methods: Subjects who were over 20 years of age, and who had information regarding BMI, past history of diabetes, and fasting blood glucose levels (n=16 048), were selected from the Korea Multi-center Cancer Cohort study participants. By 2008, a total of 1290 participants had died; 251 and 155 had died of CVD and stroke, respectively. The hazard for deaths was calculated with hazard ratio (HR) and 95% confidence interval (95% CI) by Cox proportional hazard model. Results: Compared with the normal population, patients with diabetes were at higher risk for CVD and stroke deaths (HR, 1.84; 95% CI, 1.33 to 2.56; HR, 1.82; 95% CI, 1.20 to 2.76; respectively). Relative to subjects with no diabetes and normal BMI (21 to 22.9 $kg/m^2$), lean subjects with diabetes (BMI <21 $kg/m^2$) had a greater risk for CVD and stroke deaths (HR, 2.83; 95% CI, 1.57 to 5.09; HR, 3.27; 95% CI, 1.58 to 6.76; respectively), while obese subjects with diabetes (BMI ${\geq}25kg/m^2$) had no increased death risk (p-interaction <0.05). This pattern was consistent in sub-populations with no incidence of hypertension. Conclusions: This study suggests that diabetes in lean people is more critical to CVD deaths than it is in obese people.