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Circadian rhythm disturbance caused by shift work has adverse effects on the metabolic homeostasis of the liver. Disruption of the metabolic homeostasis of the liver causes fat accumulation in the liver. The aim of this study was to investigate the correlation between shift work and non-alcoholic fatty liver disease (NAFLD) among male workers in the steel manufacturing industry of Korea.Based on medical examination data collected in June 2020, 2,511 male subjects from one steel manufacturing company in Korea were selected in total. NAFLD was evaluated using abdominal ultrasound, which was performed by two experienced radiologists. The multinomial logistic regression analysis was performed by adjusting for age, physical activity, smoking history, alcohol consumption, body mass index, waist circumference, blood pressure, blood glucose, lipidemia, liver function test, employment duration, and hepatotoxic materials exposure status.Compared to daytime workers, the odds ratio (OR) of moderate-severe NAFLD in shift workers was 1.449 (95% confidence interval [CI], 1.028-2.043). Compared to daytime workers, the ORs of moderate-severe NAFLD were significantly higher for the group that engaged in total shift work for more than 20 years (OR, 2.285; 95% CI, 1.051-4.970), the group that was not allowed to sleep during night shift work (OR, 1.463; 95% CI, 1.030-2.078), and the group that consumed food during night shift work (OR, 1.580; 95% CI, 1.093-2.284).There was a correlation between shift work and moderate-severe NAFLD in male steel manufacturing workers. There will be a need for more research related to the correlation of shift work with steatohepatitis and cirrhosis in the future.

Haenyeo is a woman who has the job of collecting seafood in the Jeju Sea at an average temperature of 13°C-14°C. The purpose of this study was to examine the cold acclimatization and occupational characteristics of Haenyeo through biomarkers such as orexin and irisin related to heat generation in the body.Twenty-one Haenyeo and 25 people with similar age, body type, and body mass index were selected as the control group (Control G). In the cold exposure experiment, a climate chamber was set to 5°C and both feet were immersed in a 15°C water tank for 30 minutes. Tympanic temperature (TOrexin levels were elevated after cold stimulation from 12.17 ± 4.44 to 12.95 ± 4.53 ng/mL (Haenyeo group [Haenyeo G],Our experimental results suggest that Haenyeo G were relatively superior in cold tolerance to Control G under cold exposure conditions. Haenyeo's cold acclimatization is due to the basic differences in pyrogens regarding body temperature control such as orexin and irisin. This means that Haenyeo are advantageous for cold survival.

This study aimed to investigate the association between lead exposure and serum gamma-glutamyl transpeptidase (γGT) levels as an oxidative stress marker in male steelworkers.Data were collected during the annual health examination of workers in 2020. A total of 1,654 steelworkers were selected, and the variables for adjustment included the workers' general characteristics, lifestyle, and occupational characteristics. The association between the blood lead level (BLL) and serum γGT level was investigated by multiple linear and logistic regression analyses. The BLL and serum γGT values that were transformed into natural logarithms were used in multiple linear regression analysis, and the tertile of BLL was used in logistic regression analysis.The geometric mean of the participants' BLLs and serum γGT level was 1.36 μg/dL and 27.72 IU/L, respectively. Their BLLs differed depending on age, body mass index (BMI), smoking status, drinking status, shift work, and working period, while their serum γGT levels differed depending on age, BMI, smoking status, drinking status, physical activity, and working period. In multiple linear regression analysis, the difference in models 1, 2, and 3 was significant, obtaining 0.326, 0.176, and 0.172 (all:BLL was positively associated with serum γGT levels in male steelworkers even at low lead concentrations (5 μg/dL).

Few studies have examined rheumatoid arthritis (RA) risk and severity in Korean workers exposed to silica. We compared the hospitalization risk of RA between silica-exposed workers and the general Korean population. The study cohort consisted of male workers exposed to silica who had undergone at least one silica-associated special medical examination between 1 January 2000 and 31 December 2004 (N = 149,948). The data were from the Korea Occupation Safety and Health Agency. RA morbidity based on hospital admission records was estimated from 2000 to 2005 using the Korea National Health Insurance Service claims data. The standardized admission ratio (SAR) was calculated by dividing the observed number of admissions in silica-exposed workers by the expected number of admissions in the general reference population. For the sum of “Seropositive rheumatoid arthritis” (M05) and “Other rheumatoid arthritis” (M06), the SAR was higher in the silica-exposed group (1.34, 95% CI 1.08–1.64). For M05, workers with

Background The aim of this study was to investigate the relationship between occupational exposure to various hazards and hospital admission due to endocrine diseases in Korean male firefighters. Methods From 2000 to 2008, former and current male firefighters registered in the Korean National Emergency Management Agency were investigated based on their hospitalized health insurance admission data for the same period. Admission data for endocrine, nutritional, and metabolic diseases were obtained from the Korean National Health Insurance Service database. Standardized admission ratio (SAR) with reference to the general population of Korean men was analyzed. Results SAR for firefighters with endocrine, nutritional, and metabolic diseases was 0.56 (95% confidence interval [CI]: 0.49–0.65), which was significantly less than that of the general population of Korean men. For those with endocrine, nutritional, and metabolic diseases, SARs for those with a history of fire suppression tasks and those without experience of fire suppression tasks were 0.58 (95% CI: 0.49–0.68) and 0.53 (95% CI: 0.40–0.70), respectively. Conclusions The admission rate of Korean male firefighters due to endocrine, nutritional and metabolic diseases was significantly lower than that of the general Korean men population, the hazardous potential of endocrine disruptors remains an open question. Further studies of firefighters with longer follow-up are needed.

Background The study aimed to determine the association between shift work and metabolic syndrome and the prevalence of metabolic syndrome in the shift and day work groups among workers working in chemical plants. Methods Based on medical examination data collected in February 2019, 3,794 workers working at a chemical plant in Korea were selected. Multiple logistic regression analysis was performed by adjusting for age, sex, body mass index (BMI), drinking, exercise, smoking, employment period and organic compounds exposure. Results The prevalence of metabolic syndrome in the entire study group was 23.4%, and the prevalence and components of metabolic syndrome in shift worker; waist circumference were higher than those of day workers (84.77 ± 8.64 vs. 83.41 ± 9.42, p < 0.001), systolic blood pressure (129.89 ± 9.47 vs. 127.57 ± 9.47, p < 0.001), diastolic blood pressure (81.22 ± 7.59 vs. 79.34 ± 7.46, p < 0.001), fasting blood glucose (99.27 ± 17.13 vs. 97.87 ± 13.07, p = 0.007), triglycerides (149.70 ± 101.15 vs. 133.55 ± 105.17, p < 0.001), and decreased high-density lipoprotein (53.18 ± 12.82 vs. 55.61 ± 14.17, p < 0.001). As a result of logistic regression analysis on the risk of metabolic syndrome, even after adjusting for age, sex BMI, drinking, smoking, exercise, employment period, organic compound exposure. the odds ratio (OR) for the shift group was 1.300 for daytime workers (Model 1, OR: 1.491; 95% confidence interval [CI]: 1.273–1.747; Model 2, OR: 1.260; 95% CI: 1.070–1.483; Model 3, OR: 1.309, 95% CI: 1.081–1.585; Model 4, OR: 1.300; 95% CI: 1.063–1.591). Conclusions Shift work in chemical plant workers increased the risk of metabolic syndrome, even after adjusting for general factors. To analyze the occupational cause and risk control, it is necessary to analyze the hazardous substances the workers were exposed to and their working environment. Additionally, a large-scale prospective analysis including general factors not analyzed in this study, such as eating habits, is required.

Background Studies have investigated the relationship between long work hours and sleep disorders; however, they have focused on shift workers or specific workers who are at high risk of industrial accidents rather than wage workers in general. The purpose of this study is to investigate the effects of long work hours on sleep disorders among non-shift daytime wage workers. Methods We conducted a secondary analysis of data from the 5th Korean Working Conditions Survey. From the 50,205 total participants, we included 26,522 non-shift daytime wage workers after excluding self-employed people, business owners, unpaid family employees, and wage workers who work nights and shifts. Sleep disorders were categorized into "difficulty in falling asleep," "frequent waking," and "waking up with fatigue." Logistic regression analysis was used to evaluate the influence of long work hours on sleep disorders, and the odds ratios (ORs) were calculated. Results The OR of working > 52 hours per week was 1.183 (95% confidence interval [CI]: 1.002-1.394) for the risk of developing insomnia compared with working ≤ 40 hours per week. The OR of waking up with fatigue was 1.531 (95% CI: 1.302-1.801). Long work hours showed no significant relationship with difficulty in falling asleep or with frequent waking. Conclusions Working for extended hours was associated with increased fatigue upon waking in non-shift daytime wage workers.

Background Sleep disorders are common and serious problems for mental health. This study investigated the relationship between spouses' weekly working hours (SWWH) and sleep problems by using the data from the 5th Korean Working Conditions Survey. Methods Data from 14,921 wage workers were used in the 5th Korean Working Conditions Survey. General and occupational characteristics, sleep problems are included in the questionnaire. Multivariate logistic regression analysis was used after adjustment for general and occupational characteristics to find the relationship between SWWH and sleep problems. Results Compared to those whose spouses worked less than 40 hours per week, risk of trouble falling asleep, waking up repeatedly while sleeping, and waking up with a feeling of exhaustion and fatigue was significantly higher as SWWH increase among those whose spouses worked 53 or more hours per week (odds ratio [OR]: 1.40, 95% confidence interval [CI]: 1.16-1.70; OR: 1.50, 95% CI: 1.23-1.82; OR: 1.51, 95% CI: 1.24-1.83). Conclusions SWWH were related to sleep problems among Korean wage workers.

Background There is growing evidence that exposure to organic solvents can play a role in the etiology of rheumatoid arthritis (RA). This prospective cohort study aimed to investigate the association between RA and toluene exposure. Methods The study cohort consisted of Korea Occupational Safety and Health Agency data from male workers exposed to toluene who had undergone a toluene-associated special medical examination at least once between January 1, 2000 and December 31, 2004 (n = 148,870). The morbidity from RA based on hospital admission records was estimated from 2000 to 2005 using National Health Insurance Claim Data. The standardized admission ratio (SAR) for RA was calculated with reference to the general population. Levels of urinary hippuric acid (HA), a metabolite of toluene, were measured and used for exposure assessment. Results Toluene-exposed workers were at an elevated risk of seropositive rheumatoid arthritis (ICD-10 code M05) with an SAR of 2.38 (95% confidence interval [CI]: 1.14-4.37) and other rheumatoid arthritis (M06) with an SAR of 1.22 (95% CI: 0.91-1.59). When data were stratified according to the duration of toluene exposure and by tertiles of urinary HA level, no significant difference was apparent. Conclusion SARs of the toluene-exposed workers are higher than that of the general reference population, indicating that exposure to toluene may contribute to an increased risk of RA. Further studies of toluene-exposed workers with longer follow-up are needed.

Background This study aimed to investigate the association between job stress and suicide ideation/attempts among display manufacturing workers. Methods Data were collected from 836 workers in a display manufacturing company who participated in health screenings from May 22 to June 16, 2017. The data included general characteristics, night work, job tenure, previous physician-diagnosed chronic diseases, suicidal ideation/suicide attempts, and job stress. We investigated suicidal ideation/suicide attempts that covered the past year by using a self-reported questionnaire. Job stress was measured using the 43-item Korean Occupational Stress Scale. Multiple logistic regression analysis was used to investigate the association between job stress and suicidal ideation/suicide attempts. The mediator effect of depression on suicidal ideation/suicide attempts was tested using a series of logistic regression by applying Baron and Kenny's mediation method. Results In the model adjusting for variables (e.g., age, body mass index, smoking, alcohol consumption, regular exercise, shift work, job tenure, chronic disease and depression), physical environment (OR: 3.60, 95% CI: 1.08-12.02), lack of reward (OR: 5.31, 95% CI: 1.54-18.34), and occupation climate (OR: 7.36, 95% CI: 2.28-23.72) were correlated with suicidal ideation/suicide attempts in women. However, all subscales of job stress were not significantly correlated with suicidal ideation/suicide attempts in men. In mediation analysis, job instability and occupational climate were correlated with suicidal ideation/suicide attempts and were mediated by depression in men workers. Conclusions In women workers, the experiences of suicidal ideation/suicide attempts were significantly correlated with the physical environment, lack of reward, and occupational climate that were subscales of job stress. In men workers, depression rather than job stress was correlated with experiences of suicidal ideation/suicide attempts.

A 48 WL stacked 256-Gb V-NAND flash memory with a 3 b MLC technology is presented. Several vertical scale-down effects such as deteriorated WL loading and variations are discussed. To enhance performance, reverse read scheme and variable-pulse scheme are presented to cope with nonuniform WL characteristics. For improved performance, dual state machine architecture is proposed to achieve optimal timing for BL and WL, respectively. Also, to maintain robust IO driver strength against PVT variations, an embedded ZQ calibration technique with temperature compensation is introduced. The chip, fabricated in a third generation of V-NAND technology, achieved a density of 2.6 Gb/mm2 with 53.2 MB/s of program throughput.

Objectives: Exposure to volatile organic compounds such as trichloroethylene(TCE) and perchloroethylene(PCE), along with Agent Orange, that were issued around Camp Carroll US Army Base situated in Waegwan, Chilgok-gun, Gyeongsangbuk-do Province, Korea. The main objective of this study was to assess the exposure to TCE and PCE of residents of the area surrounding Camp Carroll. Methods: The TCE, PCE and trichloroethanol(TCEOH) concentrations in blood and trichlroroacetic acid(TCA) and TCEOH concentrations in urine were measured and analyzed in a total of 1,033 residents around Camp Carroll. TCA and TCEOH are metabolites of TCE and PCE, respectively. The information on demographic characteristics and exposure variables in relation to underground water were obtained through a questionnaire completed by the subjects. Results: TCE, PCE and TCEOH concentrations were not detected in blood. Detection rates of TCA and TECOH concentrations in urine were 98.5% and 36.6%, respectively. Creatinine-corrected average TCA and TCEOH concentrations were 12.23±23.81 μg/g and 0.66±4.31 μg/g, respectively. A significant difference was not shown between the drinking group and no drinking group for underground water, which was assumed as a potential route of exposure to TCE and PCE through the consumption of ground water. However, females drinking ground water showed a significantly higher mean level of TCA in urine than did males. There was no significant difference according to drinking ground water as a potential source of exposure to TCE and PCE in residents around Camp Carroll. Conclusions: Considering the statistical analysis of factors affecting exposure to TCE and PCE in ground water along with previous reports, TCA in urine as exposure to TCE and PCE might not be appropriate because it is found in chlorinated drinking water. Therefore, TCA concentration in urine may be the result of drinking of chlorinated water.

Background New light is being shed on the relationship between chronic neurotoxicity of the central nervous system (CNS) and exposure to low-level organic solvents (OS). However, there are few longitudinal studies with a large sample size. Methods A cohort of OS-exposed male workers was selected who had undergone an OS-associated specialized medical check-up at least once between 2000 and 2004 in Korea. The standardized admission ratios (SAR) for CNS diseases were calculated with reference to the Korean adult male population. Adjusted relative risks (ARR) were also estimated in comparison to noise-exposed male workers. Results There were 238,574 OS-exposed workers, yielding 954,772 person-years of exposure. OS-exposed workers were at elevated risk of “other extrapyramidal and movement disorders” (G25) with a SAR = 2.95 (95% CI: 1.41–5.42) and “systemic atrophies primarily affecting the CNS” (G10–G13) SAR = 2.08 (95% CI: 1.03–3.74). There were no significant differences between the OS-exposed workers and noise-exposed workers. Conclusions A limited number of CNS diseases identified through hospital admissions data and short observation periods reduced statistical power to determine effect size. OS exposure was positively associated with “other extrapyramidal and movement disorder and systemic atrophies primarily affecting the CNS. Am. J. Ind. Med. 59:392–398, 2016. © 2016 Wiley Periodicals, Inc.

Recently, the international agency for research on cancer recommended that methanol should be recognized as a medium-priority, human cancer risk. Therefore, we performed an epidemiological study to evaluate the relationship between methanol exposure and the cancer mortality of Korean workers occupationally exposed to methanol. The study cohort was composed of methanol-exposed 25,218 male workers, data on whom were available from the Korea Occupational Safety and Health Agency; all participants underwent methanol-associated medical check-ups at least once between January 2000 and December 2004. The durations of methanol exposure were categorized as

Since the first demonstration of a production quality three-dimensional (3D) stacked-word-line NAND Flash memory [1], the 3b/cell 3D NAND Flash memory has seen areal density increases of more than 50% per year due to the aggressive development of 3D-wordline-stacking technology. This trend has been consistent for the last three consecutive years [2-4], however the storage market still requires higher density for diverse digital applications. A 4b/cell technology is one promising solution to increase bit density [5]. In this paper, we propose a 4b/cell 3D NAND Flash memory with a 12MB/s program throughput. The chip achieves a 5.63Gb/mm2 areal density, which is a 41.5% improvement as compared to a 3b/cell NAND Flash memory in the same 3D-NAND technology [4].

Objectives: This study was conducted to evaluate the changes and regional differences of mortality and morbidity particularly respiratory system diseases in the area of expo sure to coal dust(Ansim area, Dong-gu, Daegu). Methods: The authors analyzed secondary data(cancer registration data, mortality data, and health insurance data) for respiratory system diseases. We calculated age standardized incidence ratio(SIR), mortality ratio(SMR), and health care utilization ratio(SHR) using those data. Results: There were no significant differences between Ansim area(or Dong-gu, Daegu) and the control area for cancer registration data and mortality data. In the results for the health insurance data, significant increased SHR in asthma was observed compared to the control area. Conclusions: Although confounders such as selection bias were not clearly ruled out, our findings reveal increased asthma SHR in the area of exposure to coal dust. Further prospective studies are required to clarify the increasing respiratory disease due to exposure to coal dust.

Objectives: This study was conducted to better understand the relationship between health effects and exposure to dusts from a briquette fuel complex in Ansim, Daegu, Korea. Methods: The subjects of this study consisted of 2,980 persons over 40 years old who had lived 20 years or more around a briquette fuel complex in Daegu. We conducted a questionnaire survey, and chest radiography was performed. In addition, chest computed tomography(CT) (335 cases) and pulmonary function test(PFT) (658 cases) were done. Pneumoconiosis was diagnosed if one of three radiologists determined(or suspected) pneumoconiosis. We also conducted in-depth interviews for pneumoconiosis cases. We defined the exposed group as subjects residing within a 500 meter radius from the walls of the briquette fuel complex, and the others were defined as the control group. Results: Subjects in the exposed and control groups are respectively 715(24%) and 2,265 cases(76%). Major respiratory symptoms in the exposed group such as sputum, dyspnea, chest tightness and wheezing were significantly higher than in the control group. By chest radiography, 173 cases of pneumoconiosis or suspicious pneumoconiosis were detected. By PFT, 62 cases(29.5%) of chronic obstructive pulmonary disease(COPD) among 210 asymptomatic subjects were detected. Finally, by chest CT we concluded 28 cases to be pneumoconiosis, and eight cases among them proved to be pneumoconiosis by environmental exposure. Conclusions: Through this study, we concluded that health outcomes such as respiratory symptoms, pneumoconiosis, and COPD were caused by continuous exposure to dusts from the briquette fuel complex. Policies to reduce environmental exposure are needed, and cases of environmental disease should be intensively followed up by the government.

Background Limited evidence suggests that human liver toxicity is associated with exposure to polycyclic aromatic hydrocarbons (PAHs). Methods The association of urinary PAH metabolites with serum liver enzymes was tested among 288 workers at a petrochemical plant, using a general linear model (GLM) and multiple logistic regression. Results Urine 2-naphthol levels were positively correlated with serum AST after adjustment for covariates in GLM. Comparing third tertile versus first tertile of 2-naphthol levels, the odds ratios (OR) were elevated for abnormal serum AST levels [OR = 4.1 (95%CI 1.6–10.2)] and abnormal serum ALT levels [OR = 2.4 (95%CI 1.2–4.9)]. Conclusions Although confounding by alcohol intake was not completely ruled out, our findings demonstrate an association between PAHs exposure and elevation in serum liver enzymes. Urinary 2-naphthol is a biomarker of exposure to PAHs that is associated with liver toxicity. Am. J. Ind. Med. 58:764–772, 2015. © 2015 Wiley Periodicals, Inc.

The advent of emerging technologies such as cloud computing, big data, the internet of things and mobile computing is producing a tremendous amount of data. In the era of big data, storage devices with versatile characteristics are required for ultra-fast processing, higher capacity storage, lower cost, and lower power operation. SSDs employing 3D NAND are a promising to meet these requirements. Since the introduction of 3D NAND technology to marketplace in 2014 [1], the memory array size has nearly doubled every year [2,3]. To continue scaling 3D NAND array density, it is essential to scale down vertically to minimize total mold height. However, vertical scaling results in critical problems such as increasing WL capacitance and non-uniformity of stacked WLs due to variation in the channel hole diameter. To tackle these issues, this work proposes schemes for programming speed improvement and power reduction, and on-chip processing algorithms for error correction.

Objective: In May 2011, an interview with three United States Forces Korea veterans revealed that chemicals believed to be 'Agent Orange' were buried at Camp Carroll (situated in Waegwan, Chilgok-gun, Gyeongsangbuk-do, Korea) in 1978. Many hazardous chemicals, such as perchloroethylene (PCE), trichloroethylene (TCE), and organochlorines were subsequently found in a joint US-ROK environmental investigation, although dioxins or burial evidence related to 'Agent Orange' have been not uncovered. This study was carried out to investigate the relevance of hazardous chemical exposure and health effects of the residents around Camp Carroll. Methods: The authors conducted a health questionnaire survey among residents around Camp Carroll regarding Waegwan groundwater ingestion, length of residence in Waegwan, and physician-diagnosed disease history (such as cancer, hypertension, diabetes and etc.). Logistic regression was performed to identify the associations between hazardous chemical exposure and physician-diagnosed diseases. Results: Among the 5,320 residents, excluding those living outside the Waegwan area, 3,430 subjects age 30 and over were analyzed. Among females, upon correction of age, smoking history and Camp Carroll working history, a higher distribution in the Waegwan groundwater ingestion group was demonstrated for patients with physician-diagnosed cancer and hypertension. The odds ratios have a tendency to increase with increased length of Waegwan groundwater ingestion. Conclusions: This study may be limited by not adopting a cohort study for the evaluation of factors that may confound environmental exposure. Yet it is meaningful that the correlation between Waegwan groundwater ingestion and chronic diseases were found through regression analysis in female; and further, this outcome may be used as a sampling basis for a secondary epidemiologic study.

Objectives: As the suspicion was raised that ‘Agent Orange’ was reclaimed 30 years ago at Camp Carol, located in Waegwan, Gyeongsangbuk-do, the government conducted an investigation of the influence of environmental and health effects around Camp Carol through a public-private joint investigation team. As part of the investigation of population health effects, this study was carried out in order to observe changes and regional differences in diseases, particularly cancer, by year. Methods: We authors conducted an analysis of secondary health data, such as cancer registration data, mortality data, and health insurance data. We drew an age standardized incidence ratio (SIR), death rate (SDR), mortality ratio (SMR), and health care utilization rate using these data. Results: For gastric cancer in women, and other cancers in men, a significant increase in incidence was observed compared to the control area. For biliary tract cancer, gallbladder cancer, and thyroid cancer in women, and prostate cancer in men, a significant decrease in incidence was observed compared to the control area. In the national statistical analysis of data, such as health insurance data and mortality data, we did not observe a significant increase at the Waegwan region compared to other regions. Conclusions: We must consider the limitations of this study. Because thirty years have passed from the time of the estimated landfill of ‘Agent Orange’, recent national statistical data may not reflect the past real situation. Therefore, the monitoring of secondary data for health effects at the municipal level should be carried out continuously.

Objectives: This study describes the results of a mass screening and secondary questionnaire conducted among sampled residents around Camp Carroll. Methods: The subjects were sampled based on Waegwan groundwater ingestion history via a primary health questionnaire survey. However, the study population included voluntary participants and there were no grounds for disqualification. Among the 1,033 residents, excluding people living outside Waegwan, 844 subjects age 30 and over were analyzed. History of physician-diagnosed disease (including detailed history of cancer), eating habits, drinking and smoking histories were queried through questionnaires. Health screening consisted of a blood pressure check and blood test (complete blood cell, liver enzyme, lipid, blood sugar test, etc.). Results: The proportion of abnormal gamma-glutamyltransferase levels was higher in the groundwater ingesting female group than the non-ingesting female group. The odds ratios of the ingested '1 to 9 years' and '10 years and over' groups were 3.09 and 0.87, respectively. Proportions of hypertension in males, abnormal serum triglyceride levels in all and in females, and abnormal serum high density lipoprotein cholesterol levels in males were higher in the '10 to 29-year' resident group than in the '1 to 9 year' group. However, there were no significant trends according to length of residence. Conclusions: Physician-diagnosed prevalence and laboratory test results are not different by histories of Waegwan groundwater ingestion and by length of residence. Even if there are partially significant differences, they do not tend to follow increases of exposure amount and trends.

Methods: We designed questionnaires to evaluate awareness of 3 major zooneses. We conducted a questionnaire survey to assess knowledge of the general characteristics of them, information sources for the awareness of zooneses, and the mode of transmission. Subjects were 716 workers from 482 dairy farms in Gyeonggi province. Results: The awareness levels for brucellosis, Q fever, and EHEC were 90.2%, 2.5% and 56.6%, respectively. Awareness of brucellosis and EHEC were tended to increase with higher number of school years. Television was the most common route of information for these zoonoses. Most common responses for questions concerning the method of transmission for each zoonoses, 'Contact with parturient fluid or placenta of animal' was 63.2% for brucellosis, 'Ingestion of raw meat or residual product' was 66.7% and 64.2% for Q fever and EHEC, respectively. The most common reason why dairy farmers think that it is difficult to prevent zoonoses was the inconvenience of wearing protection. Conclusions: Education programs for zoonoses, especially Q fever, are needed for dairy farmers. In addition, publicity information activities about prevention of zoonoses are needed for high risk groups, such as the dairy farmers surveyed.

Today's explosive demand for data transfer is accelerating the development of non-volatile memory with even larger capacity and cheaper cost. Since the introduction of 3D technology in 2014 [1], V-NAND is believed to be a successful alternative to planar NAND and is quickly displacing planar NAND in the SSD market, due to its performance, reliability, and cost competitiveness. V-NAND has also eliminated the cell-to-cell interference problem by forming an atomic layer for charge trapping [2], which enables further technology scaling. However, the etching technology required for creating a channel hole cannot keep up with the market-driven WL stack requirement. Therefore, total mold height reduction is unavoidable and this creates several problems. 1) reduced mold height increases resistance and capacitance for WLs due to the thinner layers being used. 2) channel hole critical dimension (CD) variation becomes problematic because the additional mold stack height aggravates uniformity, thereby producing WL resistance variation. Consequently, read and program performance degradation is inevitable, furthermore their optimization becomes more challenging.

In this work, we demonstrated comparative study of the WL driving method in 256-Gb VNAND with 16KB page size. The fixed pulse width (FPW) which uses the fixed WL pulse width with incremental voltage has a large tPROG due to the decreased Vth shift in the later ISPP loop. The incremental pulse width (IPW) which incrementally increases the programming voltage and pulse width overcomes the small Vth shift problem in the later loop. In addition, the optimization methods for FPW and IPW are presented to obtain a small tPROG considering the narrow Vth distribution of NAND cell after programming operation. The comparison of the WL driving methods is performed by HSPICE simulation using the 0.25-μm PTM model with the parasitic RC in 16KB page size.

Limited evidence suggests that human liver toxicity is associated with exposure to polycyclic aromatic hydrocarbons (PAHs).The association of urinary PAH metabolites with serum liver enzymes was tested among 288 workers at a petrochemical plant, using a general linear model (GLM) and multiple logistic regression.Urine 2-naphthol levels were positively correlated with serum AST after adjustment for covariates in GLM. Comparing third tertile versus first tertile of 2-naphthol levels, the odds ratios (OR) were elevated for abnormal serum AST levels [OR = 4.1 (95%CI 1.6-10.2)] and abnormal serum ALT levels [OR = 2.4 (95%CI 1.2-4.9)].Although confounding by alcohol intake was not completely ruled out, our findings demonstrate an association between PAHs exposure and elevation in serum liver enzymes. Urinary 2-naphthol is a biomarker of exposure to PAHs that is associated with liver toxicity.

Most memory-chip manufacturers keep trying to supply cost-effective storage devices with high-performance characteristics such as smaller tPROG, lower power consumption and longer endurance. For many years, every effort has been made to shrink die size to lower cost and to improve performance. However, the previously used node-shrinking methodology is facing challenges due to increased cell-to-cell interference and patterning difficulties caused by decreasing dimension. To overcome these limitations, 3D-stacking technology has been developed. As a result of long and focused research in 3D stacking technology, 128Gb 2b/cell device with 24 stack WL layers was announced in 2014 [1].

An outbreak of acute hemorrhagic conjunctivitis (AHC) caused by coxsackie A24 (CA24) virus occurred in South Korea in 2002. CA24 was isolated for the first time from patients with AHC. Therefore, this study was conducted to understand the transmission routes and prevent another AHC outbreaks.The authors conducted a questionnaire survey among 1, 730 students from 2 middle schools and 1 technical high school in Gyeongju city. For statistical analysis the chi-square test was used, and chi-square for trend method showing a level of significance less than plt; 0.05 was proven to be significant. Variables which were proven to be significant in univariate analysis were analysed by multiple logistic regression.The attack rate was 57.1%. The student groups with rubbing one's own eyes, computer usage, and sharing cellular phone had a significantly higher AHC attack rate (plt; 0.05). According to the multiple logistic regression, the odds ratios for male, high school, computer use, sharing cellular phone, and rubbing one's own eyes were significant (plt; 0.05).The most significant feature of this outbreak was that many students rubbed their own eyes following contact with AHC patients in a deliberate attempt to avoid going to school. Other transmission methods were computer usage and sharing cellular phone. In the future, health and school authorities must plan new strategies for the prevention of AHC.

An outbreak of salmonellosis occurred among the students and staff of D primary school in Yeongcheon-si, 2004. This investigation was carried out to prevent any recurrence of this outbreak and to study the infection source and transmission of the salmonellosis.The authors conducted a questionnaire survey among 1,205 students and staff members from D primary school about the ingestion of the school lunch and drinking water, and the manifestation of their symptoms. The author examined rectal swabs, the tap water and microorganism cultures, and we also investigated the dining facility and water supply facility.The diarrheal cases were defined as the confirmed cases or the persons who had diarrhea more than one time with symptoms such as fever, vomiting and tenesmus. The diarrheal attack rate was 28.0%. Ingestion of fried bean curd with egg had a significantly high association with the diarrheal attack rate (p0.05), and the relative risk of the fried bean curd with egg was 10.68 (95% CI=3.88-29.41), as was determined by logistic regression analysis. The bacterial counts in the tap water of the food preparation room and toilet (first floor) exceeded the maximum permissible counts. S. Enteritidis bacteria were only cultured from the fried bean curd with egg of all the supplied foods on September 3, 2004.The major cause of salmonellosis was presumed to be the contaminated bean curd via contaminated tap water due to a water leak of a school water pipe. This contaminated bean curd was under prepared, which allowed the S. Enteritidis to survive and multiply prior to its ingestion.

An outbreak of shigellosis occurred among students and staff of S primary and middle school, Seongju-gun, in 2003. This investigation was carried out to institute an effective counterplan, and study the infection source and transmission of the shigellosis.The authors conducted a questionnaire survey among 235 students and staff from S preschool, primary and middle school relating to the ingestion of school lunch and the manifestation of symptoms. Also, the author investigated the drinking water, feeding facility and reconstructed cooking process of the food presumed to be the cause of the shigellosis. The diarrhea cases were defined as confirmed cases and those cases who had had diarrhea more than one time, accompanied with symptoms such as fever, vomiting and tenesmus.From rectal swabs 20 people, between June 28 and July 4, 2003, were confirmed with shigellosis. The diarrhea attack rate was 40.0%. Those who had ingested tomatoes and cubed radish kimchi had significantly higher diarrhea attack rates (p0.05), with the relative risk of tomatoes being 2.69 (95% CI: 0.98-7.42). The major cause of shigellosis was presumed to be from contaminated tomatoes due to cooking with rubber gloves containing holes.The cooks in charge of school lunches must make doubly sure to not only attend to their sanitation, but also to manage the table wear and items used in providing school lunches. The health care authority should introduce higher-leveled criteria for health care among cooks, so that they cannot cook when the have a case of any infectious disease.