• 한국생활과학회지
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• 제20권3호
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• pp.637-649
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• 2011

The purpose of this study was to analyze employees' practice levels and knowledge of sanitation at school foodservice operations, to examine the sanitation conditions of current school foodservice, and to suggest an effective sanitary training program. A questionnaire survey was conducted on a total of 578 subjects and 501 reponses were made available for this study. The collected data was analyzed using SPSS of windows. The main results can be summarized as follows: Training through handouts was the most effective (53.2%) and lack of time caused by overwork (57.1%) made the practice of sanitation training difficult. The degree of employees' perceptions of the necessity of sanitary training programs was marked at 4.18 points. According to the foodservice employees' evaluation about the knowledge of sanitation concerning the sanitary training program contents, the area of environmental sanitation (96.3%) was the highest while food poisoning control (72.9%) was lowest. Foodservice employees' practice levels was ranked above 4 points (out of 5 points) in 9 areas. Practice levels of cleaning and disinfection management were highest while that of safety management was lowest. About the food service employees' practice levels of sanitation, the degree of practice and the application of knowledge was 4.39 points. There was a significantly positive correlation between the practice level of sanitation and sanitation knowledge(p<.01). Thus, educational material needs to be standardized in order to improve employees' sanitation practice level.

• Membrane and Water Treatment
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• 제8권3호
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• pp.279-292
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• 2017

This study was aimed at ultrafiltration (UF) as a pretreatment before reverse osmosis (RO) within the scheme of hybrid reverse osmosis-multistage flush (RO-MSF) desalination. Seawater at elevated temperature (after MSF heat-exchangers) was used as a feed in this process. The pretreatment system was represented as a set of functionally-linked technological segments such as: UF filtration, backwashing, chemical- enhanced backwashing, cleaning, waste disposal, etc. The process represents the sequences of operating cycles. The cycle, in turn, consists of the following unit operations: filtration, backwashing and chemical-enhanced backwashing (CEB). Quantitative assessment was based on the following indicators: normalized permeability, transmembrane pressure, specific energy and water consumption, specific waste generation. UF pre-treatment is accompanied by the following waste streams: $W1=1.19{\times}10$ power of $-2m^3$ (disposed NaOCl with 0.0044% wt.)/$m^3$ (filtrate); $W2=5.95{\times}10$ power of $-3m^3$ (disposed $H_2SO_4$ with 0.052% wt.)/$m^3$(filtrate); $W3=7.26{\times}10$ power of $-2m^3$ (disposed sea water)/$m^3$ (filtrate). Specific energy consumption is $1.11{\times}10$ power of $-1kWh/m^3$ (filtrate). The indicators evaluated over the cycles with conventional (non-chemical) backwashing were compared with the cycles accompanied by CEB. A positive impact of CEB on performance indicators was demonstrated namely: normalized UF resistance remains unchanged within the regime accompanied by CEB, whereas the lack of CEB results in 30% of its growth. Those quantitative indicators can be incorporated into the target function for solving different optimization problems. They can be used in the software for optimisation of operating regimes or in the synthesis of optimal flow- diagram. The cycle characteristics, process parameters and water quality data are attached.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 춘계학술대회
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• pp.281-284
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• 2011

최근 유사석유제품 판매와 정량주유를 하지 않는 주유소로 인해 많은 운전자들이 피해를 입고 있고, 이러한 현상들이 점점 증가하여 앞으로 그 피해는 더 늘어날 전망이다. 유사석유제품을 사용함으로써 발생하는 피해는 연료계통의 윤활작용 및 자가 청정기능 문제, 부품의 조기 노후화 및 연료계통의 불순물 누적, 정품 휘발유와의 연소속도 차이로 인한 엔진의 부담 가중, 배기가스의 유독성물질 배출, 엔진오일과 확인되지 않은 화학적 반응 등이 발생하게 되는 문제점이 있다. 이러한 피해를 예방하기 위해 OBD-II 프로토콜로 자동차의 주행 내부정보를 받아 유사석유제품과 정량주유를 측정하고자 한다. 본 논문에서는 WinCe 기반의 개발보드를 이용하여 WiFi 통신을 지원하는 OBD-II 스캐너를 통해 주행 내부정보를 받아와서 현재 차량의 유사석유제품판별 시스템과 정량주유 시스템을 구현하였다.

• The Journal of Advanced Prosthodontics
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• 제6권2호
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• pp.79-87
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• 2014

PURPOSE. The aim of this study was to determine the efficiency of Erbium, Chromium: Yttrium-Scandium-Gallium-Garnet laser in different output powers for removing permanent resin cement residues and therefore its influence on microshear bond strength compared to other cleaning methods. MATERIALS AND METHODS. 90 extracted human molars were sectioned in 1 mm thickness. Resin cement was applied to surface of sliced teeth. After the removal of initial cement, 6 test groups were prepared by various dentin surface treatment methods as follows: no treatment (Group 1), ethylene diamine tetra acetic acid application (Group 2), Endosolv R application (Group 3), 1.25 W Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet laser irradiation (Group 4), 2 W Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet laser irradiation (Group 5) and 3.5 W Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet laser irradiation (Group 6). The topography and morphology of the treated dentin surfaces were investigated by scanning electron microscopy (n=2 for each group). Following the repetitive cementation, microshear bond strength between dentin and cement (n=26 in per group) were measured with universal testing machine and the data were analyzed by Kruskal Wallis H Test with Bonferroni correction (P<.05). Fracture patterns were investigated by light microscope. RESULTS. Mean microshear bond strength ${\pm}$ SD (MPa) for each group was $34.9{\pm}17.7$, $32.1{\pm}15.8$, $37.8{\pm}19.3$, $31.3{\pm}12.7$, $44.4{\pm}13.6$, $40.2{\pm}13.2$ respectively. Group 5 showed significantly difference from Group 1, Group 2 and Group 4. Also, Group 6 was found statistically different from Group 4. CONCLUSION. 2 W and 3.5 W Erbium, Chromium: Yttrium-Scandium-Gallium-Garnet laser application were found efficient in removing resin residues.

• 한국산업보건학회지
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• 제19권3호
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• pp.280-287
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• 2009

High-tech microelectronics industry is known as one of the most chemical-intensive industries. In Korea, Microelectronics industry occupied 38% of export and 16% of working employees work in microelectronics industry. But, chemical information and health hazards of high-tech microelectronics manufacturing are poorly understood because of rapid development and its penchant for secrecy. We need to investigate on chemical use and exposure control. We Site-visits to 6 high-tech microelectronics manufacturing company which have cleanroom work using over 1,000kg organic solvents (5 semi-conductor chips and its related parts company, 1 liquid crystal display (LCD)). We reviewed their data on chemical use and ventilation system, and measured TVOCs (Total Volatile Organic Compounds) and carbon dioxide concentration. All cleanroom air passed through hepa filters to acheive low particle levels and only 1 cleanroom uses carbon filters to minimize the organic solvents exposures In TVOC screening test, Cleanroom for semi-conductor chips and its related parts company with laminar down flow system (e.g. class 1~100) showed nondetectable level of TVOCs concentration, but Cleanroom for liquid crystal display (LCD) with conventional flow system (e.g. class 1,000~10,000) showed 327 ppm as TVOCs. Acetone concentration in cleanroom for Jig cleaning, LC Injection, Sealing processes were 18.488ppm (n=14), 49.762 ppm (n=15), 8.656 ppm (n=14) as arithmetric mean. Acetone concentration in cleanroom for LCD inspection process was 40ppm (n=55) as geometric mean, where the range was 7.8~128.7ppm and weakly correlated with ventilation rate efficiency(r=0.44, p<0.05). To control organic solvents in cleanrooms, chemical and carbon filters should be installed with hepa filters. Even though their volatile organic compounds concentration was not exceed to occupational exposure limits, considering of entrance limited cleanroom environment, long-term period exposure effects and adverse health effects of cleanroom worker need further reseach.

• Journal of Korean Neurosurgical Society
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• 제59권5호
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• pp.458-465
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• 2016

Objective : The aim of this study is to analyze the differences in the incidence, predicting factors, and clinical course of chronic subdural hematoma (CSDH) following surgical clipping between unruptured (UIA) and ruptured intracranial aneurysm (RIA). Methods : We conducted a retrospective analysis of 752 patients (UIA : 368 and RIA : 384) who underwent surgical clipping during 8 years. The incidence and predicting factors of CSDH development in the UIA and RIA were compared according to medical records and radiological data. Results : The incidence of postoperative CSDH was higher in the UIA (10.9%) than in the RIA (3.1%) (p=0.000). In multivariate analysis, a high Hounsfield (HF) unit (blood clots) for subdural fluid collection (SFC), persistence of SFC ${\geq}5mm$ and male sex in the UIA and A high HF unit for SFC and SFC ${\geq}5mm$ without progression to hydrocephalus in the RIA were identified as the independent predicting factors for CSDH development (p<0.05). Conclusion : There were differences in the incidence and predicting factors for CSDH following surgical clipping between UIA and RIA. Blood clots in the subdural space and persistence of SFC ${\geq}5mm$ were predicting factors in both UIA and RIA. However, progression to hydrocephalus may have in part contributed to low CSDH development in the RIA. We suggest that cleaning of blood clots in the subdural space and efforts to minimize SFC ${\geq}5mm$ at the end of surgery is helpful to prevent CSDH following aneurysmal clipping.

• 한국산업보건학회지
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• 제26권3호
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• pp.301-306
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• 2016

Objectives: Direct-reading instrument(Photoionization detectors, PID) and quantitative analysis using active type air sampling (Gas chromatography-flame ionization detector, GC-FID) were tested to evaluate their ability to detect volatile organic compounds(VOCs) in a semiconductor manufacturing plant. Methods: The organic compounds used were acetone and ethanol which are normally used as cleaning solutions in the semiconductor manufacturing. The evaluation was based on the preparation of test solutions of known acetone and ethanol concentration in a chamber($600{\times}600{\times}1150mm$). Samples were prepared that would be equivalent to 5~100 ppm for acetone and 10~ 200 ppm ethanol. GC-FID and PID were evaluated simultaneously. Quantitative analysis was performed after sampling and the direct-reading instrument was checked using real-time data logging. Results: Positive correlations between PID and GC-FID were found for acetone and ethanol at 0.04~2.4% for acetone(TLV: 500 ppm) and 0.1~8.3% for ethanol(TLV: 1000 ppm). When the sampling time was 15 min, concentration of test solution was the most similar between measurement methods. However, the longer the sampling time, the less similar the results. PID and GC-FID had similar exposure patterns. Conclusions: The results indicate that PID and GC-FID have similar exposure pattern and positive correlation for detection of acetone and ethanol. Therefore, PID can be used for exposure monitoring for VOCs in the semiconductor manufacturing industry. This study has significance in that it validates measuring occupational exposure using a portable device.

• 한국치위생학회지
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• 제10권6호
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• pp.1073-1081
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• 2010

Objectives : The purpose of this study was to examine the oral health awareness and practice of workers. Methods : The subjects in this study were 200 workers in a working place located in Taean-gun, Chung-Nam Province. The data for this study was obtained by means of a self-administered questionnaire. Results : 1. An average of awareness for the oral health of workers was $2.60{\pm}0.44$ points out of 4. They were most aware of the item that toothbrushing should be done after meals($3.06{\pm}0.42$), and the second most widely recognized item was that toothbrushing should be done before bedtime($2.73{\pm}0.60$). 2. An average of practice for the oral health of workers was $2.54{\pm}0.32$ points out of 4. They did the best was brushing their teeth after meals($2.97{\pm}0.33$), followed by cleaning the tongue during toothbrushing($2.91{\pm}0.45$). 3. Awareness of oral health was significantly higher in such groups, including the female, college graduates, unmarried(p<0.05). 4. Practice of oral health was significantly higher in such groups, including the female, college graduates(p<0.05). Conclusions : To reform and improve of the system, incremental oral health care system for workers is needed. and oral health education is needed to increase the motivation of workers to control their basic dental disease.

• 한국치위생학회지
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• 제16권1호
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• pp.11-18
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• 2016

Objectives: The purpose of the study was to compare the oral health related characteristics between a long-term patients and general population. Methods: A direct interview questionnaire was completed by 160 patients and 165 general people from January 16 to April 31, 2014. The questionnaire consisted of general characteristics of the subjects, subjective health status, oral health behaviors, and needs of oral health. The data were analyzed using SPSS 18.0 program. Results: The long-term patients reported that most of them were denture wearers(38.1%), and had oral disease symptoms(62.5%) and xerostomia(65.6%). Most of the long-term patients were ex-smoker(31.3%) and did not receive regular dental check-up(92.5%). They did not know tooth brushing method(31.3%) and brushed their teeth less than twice a day(47.5%). Those who used tooth brush for more than 6 months accounted for 47.5%. Most of them did not use auxiliary oral hygiene devices(85.6%). The patients answered that oral health is not important(6.9%), oral health education is not necessary(7.5%), and oral cleaning(26.3%) should be included in oral health education. Conclusions: The self-reported oral health status of the long-term patients much more serious than the general population. It is necessary to educate the continuing oral health management program for the long-term patients.

• 대한임상독성학회지
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• 제16권1호
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• pp.15-24
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• 2018

Purpose: This study was conducted to analyze the factors associated with intoxicated patient's disposition in the pediatric emergency department. Methods: We retrospectively evaluated pediatric intoxicated patients visiting the pediatric emergency department of a hospital between January 1, 2011 and December 31, 2013. Specifically, we analyzed the association between hospitalization recommended rate and the following variables: patient age group, symptoms, intentional poisoning, decontamination and toxic level of substance. Results: We collected data from 345 patients. A high incidence was noted in the 1-4 years of age group and 10-15 years of age group. Unintentional poisoning occurred in 306 patients (88.7%). A total of 115 patients (33.3%) had symptoms when visiting. Forty three patients (12.5%) ingested cleaning substances, which was the most common agent. Potentially-toxic level was the most common level of the substance. The hospitalization recommended rate associated with visits in 2011 was 2.5 times greater than in 2012 and 2013, decontamination was 2.0 times greater than no decontamination, and poisoning with potentially-toxic substances was 2.6 times greater than poisoning with other toxic substances. Additionally, the hospitalization recommended rate associated with symptomatic patients was 2.4 times greater than that of asymptomatic patients and intentional poisoning was 2.4 times greater than unintentional poisoning. Conclusion: Patients with decontamination, ingestion of potentially-toxic substances, symptoms and intentional poisoning had increased hospitalization rates. In addition, the hospitalization rate for patients who visited in 2011 was greater than that of patients who visited in 2012 or 2013.