• Journal of Intelligence and Information Systems
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• v.9 no.1
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• pp.53-69
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• 2003

Many process variables in modem manufacturing processes have influence on quality of products with complicated relationships. Therefore, it is necessary to control multiple quality variables in order to monitor abnormal signals in the processes. This study proposes an integrated procedure of self-organizing map (SOM) neural network and case-based reasoning (CBR) for multivariate process control. SOM generates patterns of quality variables. The patterns are compared with the reference patterns in order to decide whether their states are normal or abnormal using the goodness-of-fitness test. For validation, it generates artificial datasets consisting of six patterns, normal and abnormal patterns. Experimental results show that the abnormal patterns can be detected effectively. This study also shows that the CBR procedure enables to keep Type 2 error at very low level and reduce Type 1 error gradually, and then the proposed method can be a solution fur multivariate process control.

• Safety and Health at Work
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• v.14 no.4
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• pp.451-456
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• 2023

Background: We conducted a case-control study to identify high-risk occupations and exposure to occupational hazards for acute myeloid leukemia (AML). Methods: When patients with AML admitted to the Department of Hematology in the study hospital for the first time are referred to the Department of Occupational and Environmental Medicine, data on occupation are collected by investigators to evaluate work-relatedness. Community-based controls were recruited through an online survey agency, and four controls per case were matched. Occupational information was estimated using structured questionnaires covering 27 specific occupations and 32 exposure agents. Conditional logistic regression analysis was performed by pairing cases and controls. Results: In the analysis of the risk of AML according to occupational classification, a significant association was found in paint manufacturing or painting work (OR = 2.22, 95% CI: 1.03-4.81) and aircrew (OR = 6.00, 95% CI: 1.00-35.91) in males, and in pesticide industry (OR = 6.89, 95% CI: 1.69-28.07) and cokes and steel industry (OR = 2.00, 95% CI: 1.18-22.06) in ≥60 years old. Moreover, the risk of AML increased significantly as the cumulative exposure to thinners increased. In the analyses stratified by sex and age, the association between pesticide exposure and AML was significant in males (OR = 3.28, 95% CI: 1.10-9.77) and in ≥60 years old (OR = 6.22, 95% CI: 1.48-26.08). Conclusion: This case-control study identified high-risk occupational groups in the Republic of Korea including paint manufacturers and painters, aircrew, and those who are occupationally exposed to pesticides or paint thinners.

• Korean Journal of Plant Resources
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• v.13 no.2
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• pp.147-153
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• 2000

Experiments were carried out to determine the effects of culturing conditions DCI(Day required for Colonization after Inoculation), CR(Contamination Rate), MD(Mycelial Density), DPI(Day required for Primordial sclerotia formation after Inoculation), yields, and degree of the foreign materials formations in Poria cocos sclerotia. The upper and bottom side of wood logs were covered with gauze, rice hull and floating leaves, vinyl, or covering cloth in order to prevent foreign material formations in p. cocos. The major results were positive in the order of rice hull, floating leaf, vinyl, gauze, and covering cloth covered and dwindled. In case of the upper and bottom sides of the wood logs covered with rice hull, DCI required 50 days more when compared with the control group(45 days) and CR was 0%, while the control group showed 2% CR. MD was excellent in case of conventional methods as against control's. DPI required 17~20 days less when compared with the control group(82 days). Yields of p. cocos in case of the upper and bottom side of wood logs covered with rice hull were 5.87kg, which is 35.7% higher than that of the control group(4.33kg), and 5.62kg in the case of upper sides cover only(increased by 29.8% compared with control), and 5.59kg in the case of bottom side cover only(increased by 29.1% compared with control), and foreign materials were none. In a separate experiment, where the upper and bottom sides of wood logs were covered with rice hull to prevent the foreign material formation, the results were as follows : Sclerotia formation status and quality of P. cocos were effective in the order of 20cm, 40cm, and 60cm of buring depth and dwindled. In 20cm of burying depth, DCI was shortened by 5 days and CR was none, while the control group showed 2% CR. MD was remarkably fine at the mulched conditions. DPI was shortened by 20 days when compared with the control(62 days).

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.4
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• pp.21-26
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• 2016

In this study, the control strategies of indoor air temperature in floor radiant heating system were researched by computer simulation. The temperature difference based time control method using the difference of indoor set temperature and indoor temperature is compared with the existing On-Off control one for heating control performances. As a result, the temperature difference based time control method shows better thermal environmental characteristics in case of selected operational conditions in comparison with existing control one.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.11
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• pp.4699-4704
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• 2015

Medical diagnostic X-ray workers are one occupational group that expose to the long-term low-dose external radiation over their working lifetime, and they may under risk of different cancers. This study aims to determine the relationship between the occupational X-ray radiation exposure and cancer risk among these workers in Jiangsu, China. We conducted Nested case-control study to investigate the occupational X-ray radiation exposure and cancer risk. Data were collected through self-administered questionnaire, which includes but not limits to demographic data, personal behaviors and family history of cancer. Retrospective dose reconstruction was conducted to estimate the cumulative doses of the x-ray workers. Inferential statistics, t-test and 2 tests were used to compare the differences between each group. We used the logistic regression model to calculate the odds ratio (OR) and 95% confidence interval (CI) of cancer by adjusting the age, gender. All 34 breast cancer cases and 45 esophageal cancer cases that detected in a cohort conducted among health workers between 1950~2011 were included in this presented study, and 158 cancer-free controls were selected by frequency-matched (1:2). Our study found that the occupational radiation exposure was associated with a significantly increased cancer risk compared with the control, especially in breast cancer and esophageal cancer (adjusted OR=2.90, 95% CI: 1.19-7.04 for breast cancer; OR=4.19, 95% CI: 1.87-9.38 for esophageal cancer, and OR=3.43, 95% CI: 1.92-6.12 for total cancer, respectively). The occupational X-ray radiation exposure was associated with increasing cancer risk, which indicates that proper intervention and prevention strategies may be needed in order to bring down the occupational cancer risk.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.259-262
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• 1995

In this paper, a model of an asymptotically reliable serial production line with quailty control devices is introduced and analyzed. By an asymptotic technique and Taylor series expansion, its average production rate is approximated in a closed form. The results are applied to a case study of a surface mount system.

• IE interfaces
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• v.8 no.3
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• pp.249-257
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• 1995

Expert system is an effective approach for quality system to be automated and thus to be an essential integrating mechanism in any move towards CIM(Computer Integrated Manufacturing). A quality control expert system is introduced and its relationship to CIM is illustrated in a case study. Process control expert system developed by Kim and Sin[6] has been improved via ODBC(Open DataBase Connectivity) for efficient information network, graph representation using Windows API for rapid response and some new rules for identification of patterns in control charts.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.11
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• pp.4939-4944
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• 2016

Background: An upward trend has been noted for the incidence of prostate cancer (PCa) in Vietnam, but information is limited on modifiable factors associated with this form of cancer. This case-control study was conducted to ascertain any relationship between habitual tea consumption and PCa risk. Materials and Methods: Two hundred and fifty-three incident patients with histologically confirmed PCa and 419 (340 community-based and 79 hospital-based) controls, matched by age, were recruited in Ho Chi Minh City during 2013-2015. Information on frequency, quantity and duration of tea consumption, together with demographics, habitual diet and lifestyle characteristics, was obtained by direct interviews using a validated questionnaire. Logistic regression analyses were performed to assess associations between tea consumption variables and PCa risk. Results: The control subjects reported higher tea consumption levels in terms of cumulative exposure, frequency and quantity of tea drank than the PCa patients. After accounting for confounding factors, increasing tea consumption was found to be associated with reduced risk of PCa. The adjusted odds ratios (95% confidence intervals) were 0.52 (95% CI 0.35-0.79) and 0.30 (95% CI 0.18-0.48) for participants drinking 100-500 ml/day and > 500 ml/day, respectively, relative to those drinking < 100 ml/day. Significant inverse dose-response relationships were also observed for years of drinking and number of cups consumed daily (P <0.01). Conclusion: Habitual tea consumption is associated with a reduced risk of PCa in Vietnamese men.

• Journal of Periodontal and Implant Science
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• v.44 no.2
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• pp.85-93
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• 2014

Purpose: Low birth weight (LBW) is one of the major public health problems in India. Hence, there is a need to identify risk factors that, when modified, will reduce the burden of unhealthy children on the healthcare system. The objective of this study was to determine whether periodontitis among mothers in the rural population of India is a risk factor for LBW babies. Methods: A hospital-based case control study was conducted among 340 postpartum mothers. The cases consisted of 170 women who had given birth to babies weighing <2,500 g, while the control group consisted of 170 women who had given birth to babies weighing ${\geq}2,500g$. Details of the mothers were taken from the hospital records and through a personal interview, and a full-mouth periodontal examination was performed postpartum, which included probing depth, clinical attachment level, and bleeding on probing on six sites per tooth. Results: LBW cases had a significantly worse periodontal status than the controls, having an odds ratio (OR) of 2.94 (P=0.01). The multivariate logistic regression model demonstrated that periodontal disease is a significant independent risk factor with an adjusted odds ratio (aOR) of 2.85 for the LBW group (95% confidence interval [CI], 1.62-5.5). Other factors showing significant associations with LBW were pre-eclampsia (aOR, 4.49; 95% CI, 1.4-14.7), preterm labor (aOR, 5.5; 95% CI, 3.2-9.9), and vaginal type of delivery (aOR, 2.74; 95% CI, 1.4-5.2). Conclusions: Periodontitis represents a strong, independent, and clinically significant risk factor for LBW. Periodontal therapy should form a part of the antenatal preventive care among rural women in India.

• Journal of Preventive Medicine and Public Health
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• v.41 no.1
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• pp.51-60
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• 2008

Objectives : We examined the effect of sociodemographic factors, cancer, and psychiatric disorders on suicide by gender and age-specific patterns in South Korea. Methods : The study is a case-control study. Claim data was obtained from the national health insurance database and national death registration database. The number of people who committed suicide was 11,523, which was matched with a control group consisting of ten times as many people at 115,230 selected from the national health insurance and medical aids beneficiaries. The medical utilization of the case group was one year before death and that of the control group was from July 1,2003 to June 30, 2004. Four variables-address, economic status, presence of a psychiatric disease, and cancer-were used in multiple logistic regression analyses. Results : Living in cities or in rural areas showed a greater risk for suicide than living in a metropolitan city. Low economic status, the presence of a psychiatric disorder, and cancer were also statistically meaningful risk factors for suicide. The three major psychiatric diseases, schizophrenia, alcohol abuse, and bipolar disorder, were meaningful in all age groups, but the scale of the odds ratio differed by the age group. Only the psychiatric disorder variable was meaningful in the adolescent group, whereas a psychiatric disorder and economic status were meaningful for the young adult group, and all variables were meaningful for the middle-aged group. A psychiatric disorder and cancer were meaningful in the elderly group, economic status was meaningful for male subjects, and address was meaningful for female subjects. Conclusions : Factors such as living in city or rural areas, low economic status, the presence of a psychiatric disorder, and cancer were statistically meaningful risk factors in suicide. These factors also differed by age group. Therefore, policymakers should establish policies for suicide prevention that are relevant for each age group.