• Journal of the Society of Disaster Information
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• v.9 no.4
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• pp.449-461
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• 2013

As the hydrofluoric acid leak in Gumi-si, Gyeongsangbuk-do or hydrochloric acid leak in Ulsan, Gyeongsangnam-do demonstrated, chemical related accidents are mostly caused by large amounts of volatile toxic substances leaking due to the damages of storage tank or pipe lines of transporter. Safety assessment is the most important concern because such toxic material accidents cause human and material damages to the environment and atmosphere of the surrounding area. Therefore, in this study, a hydrofluoric acid leaked from a storage tank was selected as the study example to simulate the leaked substance diffusing into the atmosphere and result analysis was performed through the numerical Analysis and diffusion simulation of ALOHA(Areal Location of Hazardous Atmospheres). the results of a qualitative evaluation of HAZOP (Hazard Operability)was looked at to find that the flange leak, operation delay due to leakage of the valve and the hose, and toxic gas leak were danger factors. Possibility of fire from temperature, pressure and corrosion, nitrogen supply overpressure and toxic leak from internal corrosion of tank or pipe joints were also found to be high. ALOHA resulting effects were a little different depending on the input data of Dense Gas Model, however, the wind direction and speed, rather than atmospheric stability, played bigger role. Higher wind speed affected the diffusion of contaminant. In term of the diffusion concentration, both liquid and gas leaks resulted in almost the same $LC_{50}$ and ALOHA AEGL-3(Acute Exposure Guidline Level) values. Each scenarios showed almost identical results in ALOHA model. Therefore, a buffer distance of toxic gas can be determined by comparing the numerical analysis and the diffusion concentration to the IDLH(Immediately Dangerous to Life and Health). Such study will help perform the risk assessment of toxic leak more efficiently and be utilized in establishing community emergency response system properly.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.548-559
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• 1996

A series of performance measurements of positron emission tomography (PET) were performed following the recommendations of the Computer and Instrumentation Council of the Society of Nuclear Medicine and the National Electrical Manufacturers Association. We investigated the performance of the General Electric $Advance^{TM}$ PET. The measurements include the basic intrinsic tests of spatial resolution, scatter fraction, sensitivity, and count rate losses and randoms. They also include the tests of the accuracy of corrections: count rate linearity correction, uniformity correction, scatter correction and attenuation correction. GE $Advance^{TM}$ PET has bismuth germanate oxide crystals (4.0mm transaxial ${\times}$ 8.1mm axial ${\times}$ 30.0mm radial) in 18 rings, which form 35 imaging planes spaced by 4.25mm. The system has retractable tungsten septa 1mm thick and 12cm long. Transaxial resolution was 4.92mm FWHM in 2D and 5.14mm FWHM in 3D at the center. Average axial resolution in 2D decreased from 3.91mm FWHM at the center to 6.49mm FWHM at R=20cm. Average scatter fraction of direct and cross slices was 9.57%. Dead-time losses of 50% corresponded to a radioactivity concentration of $4.86{\mu}Ci/cc$ and a true count rate of 519 kcps in 2D. The accuracy of count rate linearity correction was 1.84% at the activity of $4.50{\mu}Ci/cc$. Non-uniformity was 2.06% in 2D and 2.93% in 3D. Remnant errors after scatter correction were 0.55% in 2D and 4.12% in 3D. The errors of attenuation correction were 6.21% (air), 0.20% (water), -6.32% (teflon) in 2D and 5.00% (air), 6.94% (water), 3.01% (teflon) in 3D. The results indicate the performance of GE $Advance^{TM}$ PET scanner to be well suited for clinical and research applications.

• Development and Reproduction
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• v.5 no.1
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• pp.23-33
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• 2001

When mammalian oocytes ovulate into the oviduct, associating follicular fluid components are exposed to the oviductal environment, possibly resulting in the mutual interaction between fillicu1ar and oviductal fluids. In the Present study, we have demonstrated for the first time that components of fallicular fluid could be modified by the oviductal fluid. Gelatin zymographic analyses of human follicular fluid (hFF) obtained from IVF patients showed consistently the presence of 110 kDa gelatinase (GA110) in addition to many bands among which 62 kDa gelatinase was predominant. Addition of EDTA or phenanfhroline to the gelatinase substrate buffer during gel incubation abolished GA110 band whereas phenylmethylsulffnyl fluoride (PMSF) did not. In contrast, bovine oviductal fluid(bOF) exhibited only 62 kDa gelatinase. Surprisingly, when bOF was added to hFF in 1:1 ratio and then the mixture was incubated for 3 h at 37$^{\circ}$C, GA110 of hFF disappeared. Disappearance of GA110 by bOF was observed even within 30 min after mixing with hFF. Addition of aminophenylmercuric acetate (APMA) to hFF also abolished enzymatic activity of GA110 but increased the activityof 62 kDa gelatinase. However, APMA abolished many other gelatinases as well unlike bOF. Interestingly, treatment of hFF with EDTA for 3 h remarkably increased the enzymatic activity of GA110 but not that of other gelatinases. Addition of phenanthroline, PMSF or soybean trypsin inhibitor (SBTI) did not affect overall gelatinase activities. Again, addition of bOF to the hFF pretreated with any of the above proteinase inhibitors abolished the appearance of GA110. Human serum also showed GAI 10 of which activity was greatlyenhanced by EDTA treatment. Similar to hFF, serum GA110 also disappeared by the addition of bOF. Human granulosa cell homogenate did not reveal any appreciable gelatinase activity except 92 kDa gelatinase. Anti-human gelatinase A antibody reacted with 62 kDa gelatinase of hFF. Based upon these results, it is concluded that bOF could selectively degrade an isoform of gelatinase A present in hFF and human serum.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.3
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• pp.257-265
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• 2009

Statement of problem & Purpose: To study the effect of different fluoridation methods after in-office bleaching on the color of teeth during severe staining with coffee. Material and methods: 44 specimens were randomly divided into four groups. Group 1 (no bleaching, no fluoride, coffee) was served as control for the influence of coffee on the color of untreated teeth. Group 2, 3 and 4 were undergone bleaching with 35% $H_2O_2$ for 30 minutes a day on 3 consecutive days. Group 2 was remained without fluoridation. Group 3 and 4 were fluoridated for 1 hour with either Cavity shield$^{(R)}$ or pH 7 Gel$^{(R)}$. All of groups were immersed in coffee solution for 7 days. Color determination was accomplished using the spectrophotometer (VITA Easyshade$^{(R)}$). Results: ${\Delta}L$ and ${\Delta}h$ increased, whereas ${\Delta}C$ decreased in the bleached groups. Pairwise comparisons with Tukey's HSD showed that there were statistically significant differences for ${\Delta}L$ and ${\Delta}h$ between the bleached groups and the non-bleached group (P < .05). ${\Delta}L$ and ${\Delta}h$ decreased continuously, while ${\Delta}C$ showed an increase after a decrease in all of groups during immersion in coffee solution. After immersion in coffee solution for 7 days there were no statistically significant differences for ${\Delta}L$, ${\Delta}C$ and ${\Delta}h$ between the groups (P > .05). Also there were no statistically significant differences for ${\Delta}L$, ${\Delta}C$ and ${\Delta}h$ between the group 3 treated with Cavity shield. and the group 4 treated with pH 7 Gel. (P > .05). Conclusion: It was concluded that fluoridation was not beneficial to the prevention of extrinsic stains after bleaching.

• Journal of dental hygiene science
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• v.13 no.3
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• pp.223-229
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• 2013

The aim of this study was to examine the effectiveness of oral health promotion program in a group of 9~18-year-old children and adolescents living in four orphanages in Dong-gu, Daejeon. The program was based on oral disease prevention program including oral health education, fluoride application and scaling every six months. Oral health status of total 109 orphans was examined by one dentists who were trained in 2010 Korean National Oral Health Survey. Dental caries index, community periodontal index and modified patient hygiene performance index (M-PHP) were checked using dental unit chair. Child oral health impact profile (COHIP) and subjective oral health recognition survey were carried out. Compared with data of 2010 national sample, the mean of decayed, missing and filled teeth showed no difference between the subjects and test values, but the means of decayed teeth, decayed surface, toothbrushing frequency of the subjects showed to become worse with advancing years in spite of oral health promotion program. COHIP, subjective oral health status showed lower than test values, too. In M-PHP and Calculus index, the subjects showed better by periodic oral health education and scaling. We suggest that oral health promotion program for orphans include oral disease treatment program as well as preventive program to improve oral health of orphans efficiently. And, oral health promotion program has to be connected with psychological support for improving quality of life of orphans.

• Journal of dental hygiene science
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• v.18 no.2
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• pp.97-104
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• 2018

The purpose of this study was to classify risk groups according to Caries Risk Assessment (CRA) and to investigate the effect of caries prevention program after 1 year of caries prevention intervention program in 6-year-old infants with high caries risk. The subjects were selected based on responses to CRA questionnaires. At the first visit, oral examination, Cariview, bacteria and saliva flow test were performed. The caries risk group was classified accordingly. The subjects were given fluoride application and oral health education every four months and evaluated the same as the first visit after 1 year. As a result of classifying the risk level according to CRA, more than 80% of the subjects were in the high or extreme high risk. The dft index was increased in all risk groups after the intervention. There was a significant difference between the before and after intervention (p<0.05). The Cariview score showed a slight decrease after the intervention in the moderate and high risk groups. As a result of the evaluation of bacteria test, Streptococcus mutans were decreased to ${\geq}10^5CFU/ml$ saliva after intervention in all groups. Lactobacilli were decreased after intervention in high risk and extreme high risk groups. As a result of saliva flow, there was significant difference between caries risk groups before and after intervention (p<0.05). In conclusion, regular caries management has been shown to influence caries risk factors in high-caries risk children. Also, it is necessary to find out periodical dental risk management system which is suitable for domestic situation through the related studies.

• Journal of dental hygiene science
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• v.16 no.2
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• pp.176-182
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• 2016

The purpose of this study was to evaluate the in-vitro efficacy of the active ingredients of dentifrice following treatment time. The whitening effect was evaluated by a change in lightness value relative to the contact time of hydrogen peroxide, by using artificially stained hydroxyapatite discs. The anti-calculus effect was assessed based on the amount of calcium eluted from the human dental calculus by sodium pyrophosphate. Remineralization was evaluated by the Vickers hardness test following the application of sodium fluoride to bovine enamel. In order to view dentinal tubules occlusion, the formation of insoluble calcium salts by bovine dentin specimens was observed using scanning electron microscopy. Change in lightness value (${\Delta}L$) was $5.50{\pm}1.51$ after 1 min of treatment, $5.73{\pm}0.43$ after 3 min, $8.64{\pm}0.24$ after 10 min, $18.93{\pm}0.76$ after 30 min, and $27.35{\pm}0.54$ after 60 min. The amount of calcium eluted from the human dental calculus was $4.23{\pm}0.14ppm$ after 1 min of treatment, $4.51{\pm}0.04ppm$ after 3 min, $12.12{\pm}0.16ppm$ after 10 min, $17.85{\pm}0.81ppm$ after 30 min, and $25.15{\pm}0.32ppm$ after 60 min. The Vickers hardness change value (${\Delta}VHN$) was $1.96{\pm}1.44$ after 1 min, $1.52{\pm}1.06$ after 3 min, $9.06{\pm}0.15$ after 10 min, $10.83{\pm}5.13$ after 30 min, and $12.55{\pm}2.09$ after 60 min. Partial dentinal tubules occlusion was observed at 10 min and complete occlusion was evident at 60 min. In summary, the use of patch type dentifrices for 10, 30, or 60 min were 1.57 to 8.26 times more effective than using the paste type dentifrices for 1 to 3 min. Based on these findings, it is reasonable to expect that the use of patch type dentifrices for 10 min would lead to remineralization, anti-calculus and dentinal tubules occlusion effects, and that use for 30 min would result in a whitening effect.

• Journal of Oral Medicine and Pain
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• v.30 no.2
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• pp.215-230
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• 2005

The study was intended to investigate how dentists in private dental clinic thought on the present claim and review of dental insurance to reflect it in future establishing dental insurance policies. 1,465 dentists who were running own dental clinic in Pusan Metropolitan City and the south part of Kyungsang province were surveyed in February, 2004. A total of 406 copies of finished questionnaire were finally retrieved and analyzed. The findings are as follows. 1. About insurance claim affairs : Most of the subject of insurance claim was by dentist himself or dental hygienist(nurse). Agency claiming was carried under 20% of total insurance claim. 2. The degree of attendance on insurance lecture : The degree of attendance on insurance lecture was relatively low. 3. Filing a protest against insurance claim : Filing a protest against insurance claim was reavealed about half-and-half for "have been" or "have not been". 4. Private clinic dentist,s opinion about the regulations affecting review of dental insurance : Private clinic dentists opinion about current guide for insurance review of dental fee was“the guidance is difficult and unfair cutback of claim fee may be carried”. 5. The affairs about health insurance review agency : About 70% of private clinic dentists have dissatisfaction on health insurance review agency. 6. Standpoint of private clinic dentists about issuance of receipt for dental fee : About 70% of private clinic dentist have an difficulty in issuance of receipt for dental fee. 7. The affairs about change insurance noncoverage treatment to insurance coverage treatment : Most of private clinic dentists hoped that insurance coverage about full mouth scaling, pit and fissure sealant, fluoride application. But they do not hoped that insurance coverage about geriatric denture, prothodontic treatment except precious metal, photopolymerization resin treatment.

• Journal of dental hygiene science
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• v.11 no.6
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• pp.521-526
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• 2011

The purpose of this study was to evaluate the long term effect of school-based oral health program on decrease of dental caries among elementary school children. The subjects of this study were total 727 students of one elementary school in Deagu, Korea. They had received school-based oral health programs for more than one year since 2004. This school-based oral health program included regular oral examination, fluoride mouth-rinsing, pit-and-fissure sealing, APF gel application, tooth brushing instruction and take the xylitol tablet after lunch during school days. The subjects' oral health status were examined by two calibrated dentists every year from 2004 to 2009. The DMFS index of $1^{st}$ grade to $6^{th}$ grade experimental and control group was 0.07, 0.39, 0.55, 0.67, 0.81, 1.79 and 0.31, 0.86, 1.07, 1.04, 2.71, 3.08 respectively. It's significantly different in $5^{th}$ grade(p<0.001) and $6^{th}$ grade(p=0.018) when it compare with control group. This study partially showed effect of school-based oral health programs on decrements of dental caries. This program should be expanded widely among elementary school in Korea. Xylitol tablet also recommended to included in school-based oral health programs.

• Journal of dental hygiene science
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• v.10 no.5
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• pp.379-385
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• 2010

The purpose of this study was to examine the oral health knowledge and oral health practice of teachers in early childhood education institutions. The subjects in this study were 169 teachers who worked in early childhood education institutions. After a survey was conducted, the collected data were analyzed with a SPSSWIN 14.0 program. The findings of the study were as follows: 1. Concerning oral health knowledge, they got a mean of 7.97(9), 2.66(3), 2.86(5), 2.42(5) and 1.04(2) respectively in knowledge on dental caries, toothbrushing, periodontitis, fluoride and diet. Overall, they got a mean of 16.98 in 24 items, and the score corresponded to approximately 70 out of 100 points. 2. As for oral health practice, tongue cleaning(4.22) was what they did the most to take care of their oral health, and they just got 2.60 in regular dental checkup. Overall, they got about 3.11 in oral health practice. 3. Regarding relationship between general characteristics and oral health knowledge, the teachers who were in their 30s got 17.47 in overall oral health knowledge, and those with a career of five to less than 10 years got 17.50. The teachers who received college or higher education got 17.27, and the principals got 18.26. Those who had ever received education on oral health got 17.01. But the gaps between them and the others were not statistically significant. 4. As to connections between general characteristics including age and oral health practice, restricted sugar intake, regular dental checkup, the use of oral hygiene supplies, tongue cleaning and overall oral health practice were more prevailing among the older teachers, and the gaps between them and the younger teachers were statistically significant. 5. In terms of relationship between oral health knowledge and oral health practice, there was no statistically significant relationship between the two on the whole, but better oral health knowledge led to better oral health practice in each part. This study shows that various oral health education programs for the kindergarten teachers should be developed and continuous education through the programs is important to improve the knowledge of oral health and to change oral health behavior.