• Nutrition Research and Practice
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• v.11 no.5
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• pp.419-429
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• 2017

BACKGROUND/OBJECTIVES: The relationship between folate and colorectal neoplasia remains controversial. We examined the association between serum folate concentrations and colorectal adenomas in a case-control study of Korean adults and conducted a meta-analysis. SUBJECTS/METHODS: Our case-control study included 113 pairs of case and control who underwent colonoscopy and provided blood samples. We used multivariable conditional logistic regression models to obtain the odds ratios and 95% confidence interval (CIs). For meta-analysis, we identified the relevant studies by searching the PubMed database up to February 2017, included our case-control study and combined the study-specific relative risks (RRs) using a random-effects model. RESULTS: In this case-control study, we included 58 men and 55 women with colorectal adenomas and sex and fasting status matched the controls. We did not find any significant association between the serum folate levels and colorectal adenomas in either men or women. For meta-analysis, a total of eleven studies were included in our analysis and classified into two groups; polyp clearance group (PC) for the studies that included participants who underwent endoscopies and had their polyps removed at baseline; and no polyp clearance group (NPC) for the studies that included participants whose histories of endoscopies were unknown or who underwent their first endoscopies. Four PC (1,311 cases and 1,672 non-cases) and eight NPC studies (3,501 cases and 11,347 non-cases) were included. The combined RRs (95% CIs) comparing the bottom with the top categories of circulating folate levels were 1.07 (0.97-1.18) for the NPC group but 1.45 (1.16-1.74) for the PC group. CONCLUSIONS: Low circulating folate levels were associated with new adenoma formation.

• Nutrition Research and Practice
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• v.14 no.2
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• pp.160-166
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• 2020

BACKGROUND/OBJECTIVES: The obese population is rapidly increasing because of reduced physical activity and a Westernized diet; consequently, various chronic diseases are more prevalent. With the increasing interest in body shape and appearance, research on body shape perceptions and accompanying weight control behaviors are needed for healthy weight management. SUBJECTS/METHODS: A cross-sectional survey was conducted on randomly selected 536 (209 men and 327 women) aged 20 to 65 years. Body mass index (BMI), body-shape perception, weight control behavior, quality of sleep, and place of residence were collected using self-reported questionnaires. Multivariable logistic regression analysis was conducted using complex design in each groups. Collected data were analyzed using the SAS 9.4 statistical package, and the significance level was set at P < 0.05. RESULTS: When these two variables were divided into four groups, they were found to influence dieting attempts. People with abnormal weights who were dissatisfied with their body shapes attempted dieting 5.23 times more than those with healthy weights and satisfaction with their body shapes. Further, those with normal weights but dissatisfaction with their bodies attempted dieting 4.45 times more than those who were satisfied with their shapes. Subjects in their 20s attempted dieting 2.53 times more than those in their 30s and 40s, and female subjects attempted dieting 2.24 times more than male subjects. CONCLUSIONS: A correct perception of one's shape can be an important factor for dietary behavior, as body shape perceptions and dieting attempts are strongly related. Additionally, healthy weight management and nutrition education are important elements to incorporate into a weight control program aimed at preventing excessive weight control behaviors and promoting correct perceptions of body shape.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.4
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• pp.82-91
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• 1997

In this paper, a design method of the boiler-turbine control system in the coal fired power plant is proposed. We need to control electric output and drum pressure and water level in drum to guarantee stable operation and save energy for generating electricity and decrease air pollution in the boiler-turbine system. This boiler-turbine control system is composed of reference model part and model following part. The multivariable boiler-turbine system is separated into 3 SISO(Single Input Single Output) systems applying the concept of relative gain matrix. Each 3 reference models for separated boiler-turbine system are composed of 1st order nominal plant and hysteresis integral control system and they make good dy¬namic response with no overshoot and fast rising time. Each fuzzy controller to follow as close as possible to the response of each reference model is designed. The robustness and the good tracking property can be achieved using 5150 fuzzy controllers when there are modeling errors, disturbances and parameter pertur¬bations. The effectiveness of the proposed design method is verified through simulations.

• Journal of Preventive Medicine and Public Health
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• v.40 no.4
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• pp.329-335
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• 2007

Objectives : To identify the effects of supplemental private health insurance on health care utilization and expenditure under the mandatory National Health Insurance(NHI) system in Korea. Methods : The data were collected by the National Cancer Center in Korea. Cancer patients who were newly diagnosed with stomach (ICD code, C16), lung(C33-C34), liver (C22), colorectal cancer(C18-C20) or breast(C50) cancer were included as study subjects. Data were gathered using a structured questionnaire from face-to-face interviews, the hospital Order Communication System (OCS) and medical records. Clinical, socio-demographic and private health insurance related factors were also gathered. The differences of health care utilization and expenditure were compared between those who have private health insurance and those who do not using t-test and multivariable regression analysis. Results : Individuals with private health insurance spent larger inpatient costs than those without, but no differences were found in utilization in other service such as hospital admissions, hospital days and physician visits. Conclusions : We found that private health insurance exerts a significant effect on the health care expenditure in inpatient service. These study results can provide a rational basis to plan a national health policy regarding private health insurance. Further studies are needed to investigate the impacts of private health insurance on cancer patients' outcomes and survival rates.

• Journal of Ocean Engineering and Technology
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• v.19 no.2 s.63
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• pp.67-73
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• 2005

This paper describes depth, heading and speed control of an underwater vehicle that has four stern thrusters of which forces are coupled in the diving and, steering motion, as well as the speed of the vehicle. The optimal linear quadratic controller is designed based on a linearized- state space model, developed by combining the dynamic equations of speed, steering and diving motion. The designed controller gives provides an optimal thrust distribution, minimizing the given performance index to control speed, depth and heading simultaneously. To validate the performance of the controller, a simulation and tank-test are carried out with DUSAUV (Dual Use Semi-Autonomous Underwater Vehicle), developed by KORDI as a test-bed for testing new underwater technologies. Optimal gains of the controller are tuned, using a computer simulation environment with a nonlinear 6-DOF numerical DUSAUV model, developed by PMM (Planner Motion Mechanism) test. To verify the performance of the presented controller in experiment, a tank-test with DUSAUV is carried out in the ocean engineering basin in KORDI. The experimental results are also compared with the simulation results to investigate the accordance of the numerical and the real mode.

• Plant Journal
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• v.13 no.4
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• pp.48-50
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• 2017

A program for analyzing the transient behaviors of industrial gas turbines was developed. Each component (compressor, combustor, turbine and ducts)of gas turbine is modeled as a fully module to enhance the expandability of the program. We used object-oriented programing for this purpose. The mass and energy balance equations are solved numerically by Multivariable Newton Raphson method. The characteristic maps for the compressor and turbine were used for predicting the performance of a gas turbine engine. Combustion in the combustor is assumed to be complete combustion. PID control is used to maintain constant rotational speed and turbine exhaust temperature by the control of the fuel flow rate and the changing of the compressor inlet guide vane angle at the same time. It was confirmed that stable control of the gas turbine was possible, even for a rapid load change.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5829-5834
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• 2012

Background: Breast cancer is the most common cancer in women worldwide. Although different metabolic factors have been implicated in breast cancer development, the relationship between hypertension and breast cancer has not been elucidated. Aim: To evaluate hypertension as a risk factor for breast cancer in Chilean women of low and middle socio-economic status. Methods: We conducted an age-matched (1:1) case-control study in 3 hospitals in Santiago, Chile. Breast cancer cases (n=170) were histopathologically confirmed. Controls had been classified as Breast Imaging Reporting and Data System I (negative) or II (benign findings) within 6 months of recruitment. Blood pressure was measured using a mercury sphygmomanometer and standardized procedures. We used 2 hypertension cut-off points: blood pressures of ${\geq}140/90$ mmHg and ${\geq}130/85$ mmHg. Fasting insulin and glucose levels were assessed, and anthropometric, sociodemographic, and behavioral information were collected. Odds ratios and 95% confidence intervals were estimated for the entire sample and restricted to postmenopausal women using multivariable conditional logistic regression models. Results: Hypertension (${\geq}140/90$ mmHg) was significantly higher in cases (37.1%) than controls (17.1%) for the entire sample and in postmenopausal pairs (44.0% compared to 23.8%). In crude and adjusted models, hypertensive women had a 4-fold increased risk of breast cancer (adjusted odds ratio: 4.2; 95% confidence interval: 1.8; 9.6) compared to non-hypertensive women in the entire sample. We found a similar association in the postmenopausal group (adjusted odds ratio: 2.8; 95% confidence interval: 1.1; 7.4). A significant effect was also observed when hypertension was defined as blood pressure of ${\geq}130/85$ mmHg. Conclusion: A significant association was found between hypertension and breast cancer over the entire sample and when restricted to postmenopausal women. Hypertension is highly prevalent in Latin America and may be a modifiable risk factor for breast cancer; therefore, a small association between hypertension and breast cancer may have broad implications.

• Journal of the Korean Data and Information Science Society
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• v.21 no.2
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• pp.211-218
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• 2010

Taguchi has used the signal-to-noise ratio (SN) to achieve the appropriate set of operating conditions where variability around target is low in the Taguchi parameter design. Many Statisticians criticize the Taguchi techniques of analysis, particularly those based on the SN. Moreover, there are difficulties in practical application, such as complexity and nonlinear relationships among quality characteristics and design (control) factors, and interactions occurred among control factors. Neural networks have a learning capability and model free characteristics. There characteristics support neural networks as a competitive tool in processing multivariable input-output implementation. In this paper we propose a substantially simpler optimization procedure for parameter design using neural network without resorting to SN. An example is illustrated to compare the difference between the Taguchi method and neural network method.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.1
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• pp.18-23
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• 1989

An approach for robustness recovery of the observer-based control system is presented. The approach is developed by adding a loop with appropriate constant matrix to the observer-based closed-loop system. It will be shown that if there exists an added-loop matrix M satisfying F=MC for a feedback gain F and output matrix C, then the observer-based control systems have the same loop transfer functions as full-state feedback implementations, in other words, the former has the same relative stability and robustness as the latter.

• Journal of Digital Convergence
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• v.17 no.8
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• pp.337-346
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• 2019

This study aimed to assess trends in the prevalence, treatment, and control of diabetes according to the socio-economic level in Korean adults aged ${\geq}30$ years, using the 2007-2017 Korea National Health and Nutrition Examination Survey data. Socio-economic status was assessed based on the household income. Multivariable logistic regression and predictive margins were used to evaluate the adjusted proportion of diabetes prevalence, awareness, treatment, and adequate glycemic control. During 2007-2017, the socio-economic inequalities on diabetes prevalence were observed in both men and women. However, the gradient of inequality increased only in men (p for interaction=0.034). Diabetes awareness, treatment, and control did not show socio-economic inequalities or increasing gradients in both sexes. Monitoring of these trends should be continued, and further research on effective interventions is needed.