• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.89-99
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• 2003

The purpose of this study was to investigate the bonding of resin- based root canal sealer, AH26 when the sealer was applied as a thin layer between dentine and gutta-percha surface. In this study forty non-caries extracted human molars and resin-based root canal sealer(AH 26, DeTrey/Dentsply, Germany) were used. Disks of gutta-percha, 6mm in diameter.6mm thick (Diadent/Dentsply, Korea) for thermoplastic obturation were used and dentin surfaces were treated with 2% NaOCl(Group 1) or 2%NaOCl+17% EDTA(Group 3). Disks of gutta-Percha, 6mm in diameter.6mm thick (Diadent/Dentsply, Korea) for conventional obturation were used and dentin surface were treated with 2% NaOCl(Group 2) or 2%NaOCl+17% EDTA(Group 4). Enamel was removed by a horizontal section 1mm below the deepest portion of the central occlusal groove by using a watercooled low speed diamond saw. A second horizontal section was done around cementoenamel junction. Exposed dentin surface was cut to approximately $8{\times}8{\;}mm$ rectangular shape and was ground against 320, 400, 600 grade silicon carbide abrasive paper serially. After grinding, the dentine surface were soaked in a solution of 2% NaOCl for 30 minutes and twenty of specimens were treated with 17% EDTA solution for 1 minute. The treated specimens were washed and dried, Root canal sealer, AH26 was prepared according to the manufacture's instructions The Gutta-percha and dentin surface were coated with a thin layer of the freshly mixed seal or. The specimens were left overnight at room temperature. After their initial set, they were transferred to an incubator at $37$^{\circ}C$ for 72 h. After 72 hours, resin blocks were made. The resin block was serially sectioned vertically into stick of $1{\cdot}1mm$. Twenty sticks were prepared from each group. After that, tensile bond strength f3r each stick was measured with Microtensile Tester Failure patterns of the specimens at the interface between gutta-percha and dentin were observed under the SEM(x1000) and Stereomicroscope (LEICA M42O, Meyer Inst., TX U.S.A) at 1.25 x25 magnification. The results were statistically analysed by using a One-way ANOVA and Tukey's test. The results were as follows; 1. Tensile bond strengths($mean{\pm}SD$) were expressed with ascending order as follows: Group 1, $3.09{\pm}$ 1.05Mpa : Group 2, $6.23{\pm}1.16MPa$ : Group 3, $7.12{\pm}1.07MPa$ : Group 4, $10.32{\pm}2.06MPa$. 2. Tensile bond strengths of the group 2 and 4 used disks of gutta-percha for conventional obturation were significantly higher than that of the group 1 and 3 used fir thermoplastic obturation. (p < 0.05). 3. Tensile bond strengths of the group 3 and 4 treated with 2% NaOC1+17% EDTA were significantly higher than that of the group 1 and 2 treated with 2% NaOCl. (p < 0.05). 4. In analysis of failure patterns at the interface between sealer and gutta-percha, there were observed 49 (61%)cases of adhesive failure patterns and 31 (39%) cases of mixed failures patterns.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.2
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• pp.33-41
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• 2004

Purpose : Film has been the primary tool in coincidence testing between the light field and the radiation field, which constitutes the quality assurance list of a linear accelerator. But there is a great chance of errors being different among the observer when using film. Thus this study set out to use the BIS(Beam Image System) in addition to film in comparing and evaluating coincidence results between the two fields and in searching for the improvement measures. Materials & Methods : Photon beam of 6 and 15MV was exposed to film and the BIS using a linear accelerator. The light and radiation fields were each $50{\times}50,\;100{\times}100,\;and\;200{\times}200mm^2$. The gantry angle was $0^{\circ}$ when using film and $0^{\circ}\;and\;270^{\circ}$ when using the BIS. The devices adopted to test coincidence between the two fields were a ruler and film scanner when using film. With the BIS, the width of the scanned light and radiation fields was measured for errors with setting the X and Y axis. Results : The visual measurements of the observer with film resulted that the radiation field was bigger than the light field and that their maximum error was 1.9mm. The results were the same with the measurements using the film scanner except for the average error, which was less than 1.9mm. On the contrary, the measurements using the BIS showed that the light field was bigger than the radiation field at the gantry angle of $0^{\circ}\;and\;270^{\circ}$. The maximum error was 0.96mm, and the error range was $<{\pm}2mm$ both in the X and Y axis. The average error of ${\Delta}X$, Y was the smallest in the order of the visual film measurements, film scanner measurements, and BIS measurements Conclusion . This requires a careful measurement for accurate quality assurance since errors are much different according to each observer that tests coincidence between visual fields with film. And an observer needs to use another image device or develop a measuring device of his own if it seems necessary for accurate measurements.

• Journal of radiological science and technology
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• v.40 no.2
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• pp.261-267
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• 2017

The study has attempted to evaluate and compare the image evaluation and exposure dose by respectively applying filter back projection (FBP), the existing test method, and adaptive statistical iterative reconstruction (ASIR) with different values of tube voltage during the low dose computed tomography (LDCT). With the image reconstruction method as basis, chest phantom was utilized with the FBP and ASIR set at 10%, 20% respectively, and the change of tube voltage (100 kVp, 120 kVp). For image evaluation, back ground noise, signal-noise ratio (SNR) and contrast-noise ratio (CNR) were measured, and, for dose assessment, CTDIvol and DLP were measured respectively. In terms of image evaluation, there was significant difference in ascending aorta (AA) SNR and inpraspinatus muscle (IM) SNR with the different amount of tube voltage (p < 0.05). In terms of CTDIvol, the measured values with the same tube voltage of 120 kVp were 2.6 mGy with no-ASIR and 2.17 mGy with 20%-ASIR respectively, decreased by 0.43 mGy, and the values with 100 kVp were 1.61 mGy with no-ASIR and 1.34 mGy with 20%-ASIR, decreased by 0.27 mGy. In terms of DLP, the measured values with 120 kVp were $103.21mGy{\cdot}cm$ with no-ASIR and $85.94mGy{\cdot}cm$ with 20%-ASIR, decreased by $17.27mGy{\cdot}cm$ (about 16.7%), and the values with 100 kVp were $63.84mGy{\cdot}cm$ with no-ASIR and $53.25mGy{\cdot}cm$ with 20%-ASIR, a decrease by $10.62mGy{\cdot}cm$ (about 16.7%). At lower tube voltage, the rate of dose significantly decreased, but the negative effects on image evaluation was shown due to the increase of noise.

• Korean Journal of Psychosomatic Medicine
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• v.7 no.2
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• pp.184-195
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• 1999

Objectives : As traumatic brain injury(TBI) leaves chronic sequelae in mind and body, the injured patients should rectify the meaning and object that they have pursued in their lives and set up a new purpose in life that they may make the rest of their lives meaningful. This study was designed to investigate the purpose and quality of life levels and the influence of demographic and clinical variables on the levels in the patients with TBI, and to be of some help to their rehabilitation. Methods : In order to assess the purpose in life(PIL) and the quality of life(QOL) levels, Purpose-in-Life Test, Sickness Impact Profile, Quality of Life Index, Head Injury Symptom Ckecklist, and Neurobehavioral Rating Scale were administered to the subjects. The subjects were thirty-two patients with TBI and the same numbered normal controls. The TBI group was composed of 16 to 65 year-aged patients who had received mild or severe TBI at least 12 months before, and the controls were siblings or friends of the patients whose age, sex, and educational level were similar to them. Results : 1) The PIL and QOL levels of the patients with TBI remained significantly lower than that of control group after their symptoms of injury were stabilized(p<.01, p<.01). 2) The mean PIL score of TBI group was $58.8{\pm}23.2$, which was to be regarded as the level of existential vacuum. 3) The PIL level of TBI group was significantly correlated with the QOL level(p <.01). 4) The subgroup with lower PIL level in patients with TBI has significantly higher rate of female than that with higher PIL(p<.05), the PIL level of female patients was significantly lower than that of male patients(p <.05). 5) The significant differences in PIL levels were not found, in which comparison was performed between each pair of subgroups of patients with TBI divided by severity of injury(mild vs severe), marital status(married vs unmarried), and occupational status prior to injury(employed vs unemployed). Conclusion : The PIL of patients with TBI still remained the level of existential vacuum after symptoms of sequelae had been stabilized, The QOL level was also extremely low, and as the PIL level was low the QOL was also low. The demographic and clinical variables except sex did not have influence on the PIL level in brain-injured patients. It is suggested that every patient should admit their mental and physical limitations caused by brain injury and revise their purpose in life for successful rehabilitation.

• Journal of dental hygiene science
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• v.6 no.4
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• pp.271-276
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• 2006

This study set out to analyze the relationships between the senior citizens' dental health activities and dental health conditions, to provide basic data to develop a program for their better dental health, and finally to search for the ways to improve their life quality through dental health care. The subjects were 142 senior citizens(58 were male and 84 were female) who were 65 years old or older and visited a dental hospital or clinic in the Seoul metropolitan area from April 17 to April 28, 2006. With the cooperation from the dentists, the investigators examined their dental conditions and conducted one-on-one interviews to collect the information about their demographic characteristics, dental health activities, and subjective dental health conditions. The collected data were analyzed with T-test, ANOVA and Pearson's correlation coefficient using the SPSS WIN 11.5 program. The analysis results were summarized as follows: First, 58 men(40.8%) and 84 women(59.2%) consisted of the subject group, where percentage of the female participants was bigger Those who were aged from 65 to 69 made the biggest age group in the subjects, accounting for 58.5% with 83. Second, those who had three dental caries or less and then didn't treat them or treated them(F) accounted for the biggest percentage with 117(82.4%) and 72(50.7%) respectively. As for the remaining teeth, the biggest number of them(40 subjects, 28.2%) had three or less remaining. Third, it turned out the female subjects had a higher level of dental health activities than their male counterparts(P = 0.00). As for living expenses, those who were paid salary or earned income themselves carried out their dental health activities in a higher level than those who lived on the benefit from the government(p = 0.02). Fourth, the subjects' subjective dental health conditions had negative correlations with their dental caries not treated. And there were positive correlations between their dental caries not treated and dental caries lost and between their dental caries treated and remaining teeth. Fifth, those subjects who earned their living expenses themselves had the most dental caries treated at 5.4(p = 0.02), and there was statistically significant difference with the numbers. Sixth, those subjects who brushed their teeth in their own manner had 11.8 teeth lost(p = 0.05), which was more than the number of those who brushed their teeth in other methods. And there was statistically significant difference among them. The remaining teeth were found most at 17.3(p = 0.00) among those who brushed their upper and lower teeth separately. In addition, those who visited the public health center often had significantly more teeth treated(4.3) than others(p = 0.00).

• Tuberculosis and Respiratory Diseases
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• v.55 no.6
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• pp.570-578
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• 2003

Background : Ambient particles during Asian dust events are usually sized less than $10{\mu}m$, known to be associated with the adverse effects on the general populations. But, there has been no considerable evidence linking these particles to the adverse effects on airways. The objectives of this study was to investigate the possible adverse effects of Asian dust events on respiratory function and symptoms in subjects with bronchial asthma. Patients and Methods : From march to June 2002, Asthmatic patients who were diagnosed with bronchial challenge test or bronchodilator response were enrolled. We divided them into three groups; mild, moderate, and severe, according to the severity. Subjects with other organ insufficiency such as heart, kidney, liver, and malignancy were excluded. All patients completed twice daily diaries and recorded peak flow rate, respiratory symptom, and daily activity. Daily and hourly mean pollutant levels of particulate matter < $10{\mu}m$ in diameter($PM_{10}$), nitrogen dioxide($NO_2$), sulphur dioxide($SO_2$), ozone($O_3$) and carbon monoxide(CO) were measured at the 10 different monitoring sites. Results : Dust events occured 14 times during the study period. Daily averages of 4 air pollutant were measured with an increased level of $PM_{10}$, decreased level of $NO_2$ and $SO_2$, and no change in CO during dust days compared to those during control days. An increase in $PM_{10}$ concentration was associated with an increase of subjects with PEF variability of >20% (p<0.05), night time symptom(p<0.05), and a decrease in mean PEF (p<0.05), which were calculated by the longitudinal data analysis. Otherwise, there was no association between $PM_{10}$ level and bronchodialtor inhaler, and daytime respiratory symptoms. Conclusion : This study shows evidence that ambient air pollution, especially $PM_{10}$, during Asian dust events, could be one of the many aggravating factors at least in patients with airway diseases. This data can be used as a primary source to set up a new policy on air environmental control and to evaluate the safety of air pollution index. We also expect that this research will help identify precise components of dust, which are more linked to the adverse effects.

• Child Health Nursing Research
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• v.5 no.1
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• pp.38-47
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• 1999

This study is the study on health promoting behaviors of 6th grade students according to sex. The purpose of this study is to find the difference in the value of health in their lives among 6/sup th/ grade students according to sex, to examine the differences in practicing health promoting behaviors, and to determine the correlation between the practice of health promoting behaviors and the characteristics of these students. The subjects of this study were 177 6/sup th/ grade students who were randomly selected from two elementary schools in Taegu City. The tools used to measure health promoting behaviors were the measuring utility for practicing health promoting behaviors developed by Kyung-Suk Ki (1983) and the utility for the values of health in lives developed by Wallston, Maides and Wallston and translated by Gin Yoon (1989). The data collected were analyzed with t-test, Pearson correlation coefficient, and descriptive statistics using SPSS program. The results of the present study were as follows : 1) According to the results of the value placed in health in their lives, the number of students who placed health high in their lives was 69 boys (75%) and 64 girls (75.3%). 2) According to the results obtained from comparing the degree of practicing health promoting behaviors according to sex, in the field of personal hygiene and daily habits, the girls showed a higher degree of practice with 3.26±0.33 and the boys, 3.05±0.45(t=-3.484, p=0.001) : and in the field of contagious diseases, the girls scored significantly higher with 3.40±0.39 than the boys with 2.99±0.54(t=-2.363, p=0.019). In the filed of preventing accidents, the girls showed a meaning high significant result with 3.16±0.46 than the boys with 2.99±0.54(t=-2.362, p=0.019). When the results from the total questions in the field of health promoting behaviors were compared, the girls showed a meaningfully high correlation with 3.19±0.28 than the boys with 3.07±0.36(t=-2.601, p=0.010). Thus, the results showed that the girls, compares with the boys, practice more behaviors of personal hygiene & daily habits, prevention of communicable diseases, and prevention of accidents. 3) According to the results of the relationship between the subjects’ characteristics and their health promoting behaviors according to set in the case of the boys, they showed a meaningful positive correlation with health promoting behaviors and the current status of health (r=0.266, p=0.005). Thus, for the boys, as their health status was better, the more health promoting behaviors they showed. In the case of the girls, the meaningful variables had a correlation with the health promoting behaviors were the number of extra-curricula activities(r=0.182, p=0.047) and the birth order(r=-0.192, p=0. 024). In overall regardless of sex, the health status (r=0.188, p=0.006) and birth order(r=-0.149, p=0.024) showed a meaningful correlation with practicing health promoting behaviors. With the above results, we suggest the following proposals. 1) In elementary children of lower and upper classmen as applied with the current school age, developing a utility to measure health promoting behaviors is needed since the physical, emotional and intellectual development of these children exist. 2) According to the results of this study, developing a program for health promotion is needed in 6/sup th/ grade students.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.772-781
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• 2013

The objective of this study was to develop simple sequence repeat (SSR) markers from expressed sequence tags (EST) of lettuce (Lactuca sativa) and identify 9 germplasms from 3 wild species of lettuce and 61 commercial cultivars using the developed EST-SSR markers. A total of 81,330 lettuce ESTs from NCBI databases were used to search for SSR and 4,229 SSR loci were identified. The highest proportion (59.12%, 2500) was represented by trinucleotide, followed by dinucleotide (29.70%, 1256) and hexanucleotide (6.62%, 280) among SSR repeat motifs. Totally 474 EST-SSR primers were developed from EST and a random set of 267 primers was used to assess the genetic diversity among 9 germplasms and 61 cultivars. Out of 267 primers, 47 EST-SSR markers showed polymorphism between 7 cultivars. Twenty-six EST-SSR markers among 47 EST-SSR markers showed high polymorphism, reproducibility, and band clearance. The relationship between 26 markers genotypes and 70 accessions was analyzed. Totally 127 polymorphic amplified fragments were obtained by 26 EST-SSR markers and two to nine SSR alleles were detected for each locus with an average of 4.88 alleles per locus. Average polymorphism information content was 0.542, ranging from 0.269 to 0.768. Genetic distance of clusters ranged from 0.05 to 0.94 between 70 accessions and dendrogram at a similarity of 0.34 gave 7 main clusters. Analysis of genetic diversity revealed by these 26 EST-SSR markers showed that the 9 germplasms and 61 commercial cultivars were discriminated by marker genotypes. These newly developed EST-SSR markers will be useful for cultivar identification and distinctness, uniformity and stability test of lettuce.

• Journal of Intelligence and Information Systems
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• v.21 no.3
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• pp.79-99
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• 2015

The prediction of bankruptcy has been extensively studied in the accounting and finance field. It can have an important impact on lending decisions and the profitability of financial institutions in terms of risk management. Many researchers have focused on constructing a more robust bankruptcy prediction model. Early studies primarily used statistical techniques such as multiple discriminant analysis (MDA) and logit analysis for bankruptcy prediction. However, many studies have demonstrated that artificial intelligence (AI) approaches, such as artificial neural networks (ANN), decision trees, case-based reasoning (CBR), and support vector machine (SVM), have been outperforming statistical techniques since 1990s for business classification problems because statistical methods have some rigid assumptions in their application. In previous studies on corporate bankruptcy, many researchers have focused on developing a bankruptcy prediction model using financial ratios. However, there are few studies that suggest the specific types of bankruptcy. Previous bankruptcy prediction models have generally been interested in predicting whether or not firms will become bankrupt. Most of the studies on bankruptcy types have focused on reviewing the previous literature or performing a case study. Thus, this study develops a model using data mining techniques for predicting the specific types of bankruptcy as well as the occurrence of bankruptcy in Korean small- and medium-sized construction firms in terms of profitability, stability, and activity index. Thus, firms will be able to prevent it from occurring in advance. We propose a hybrid approach using two artificial neural networks (ANNs) for the prediction of bankruptcy types. The first is a back-propagation neural network (BPN) model using supervised learning for bankruptcy prediction and the second is a self-organizing map (SOM) model using unsupervised learning to classify bankruptcy data into several types. Based on the constructed model, we predict the bankruptcy of companies by applying the BPN model to a validation set that was not utilized in the development of the model. This allows for identifying the specific types of bankruptcy by using bankruptcy data predicted by the BPN model. We calculated the average of selected input variables through statistical test for each cluster to interpret characteristics of the derived clusters in the SOM model. Each cluster represents bankruptcy type classified through data of bankruptcy firms, and input variables indicate financial ratios in interpreting the meaning of each cluster. The experimental result shows that each of five bankruptcy types has different characteristics according to financial ratios. Type 1 (severe bankruptcy) has inferior financial statements except for EBITDA (earnings before interest, taxes, depreciation, and amortization) to sales based on the clustering results. Type 2 (lack of stability) has a low quick ratio, low stockholder's equity to total assets, and high total borrowings to total assets. Type 3 (lack of activity) has a slightly low total asset turnover and fixed asset turnover. Type 4 (lack of profitability) has low retained earnings to total assets and EBITDA to sales which represent the indices of profitability. Type 5 (recoverable bankruptcy) includes firms that have a relatively good financial condition as compared to other bankruptcy types even though they are bankrupt. Based on the findings, researchers and practitioners engaged in the credit evaluation field can obtain more useful information about the types of corporate bankruptcy. In this paper, we utilized the financial ratios of firms to classify bankruptcy types. It is important to select the input variables that correctly predict bankruptcy and meaningfully classify the type of bankruptcy. In a further study, we will include non-financial factors such as size, industry, and age of the firms. Thus, we can obtain realistic clustering results for bankruptcy types by combining qualitative factors and reflecting the domain knowledge of experts.

• Economic and Environmental Geology
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• v.55 no.2
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• pp.209-217
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• 2022

The purpose of this study was to confirm the dissolution of arsenic from the stabilized soil around abandoned coal mines by cultivation activities. Experimental soils were collected from the agricultural field around Okdong and Buguk coal mines, and the concentration of arsenic in the soil and the geochemical mobility were confirmed. The average arsenic concentration was 20 mg/kg. The soil with relatively high geochemical mobility of arsenic in the soil was used in the batch and column experiment. The limestone was mixed with soil for soil stabilization, and the mixing ratio was 3% of limestone, based on the soil weight. The phosphoric acid fertilizer (NH₄H₂PO₄) was added to the soil to simulate a cultivation condition according to the Rural Development Administration's rules. Comparative soil without mixing limestone was prepared and used as a control group. The arsenic extraction from soil was increased following the fertilizer mixing amount and it shows a positive relationship. The concentration of phosphate in the supernatant was relatively low under the condition of mixing limestone, which is determined to be result of binding precipitation of phosphate ions and calcium ions dissolved in limestone. Columns were set to mix phosphoric acid fertilizers and limestone corresponding to cultivation and stabilization conditions, and then the column test was conducted. The variations of arsenic extraction from the soil indicated that the stabilization was effectible until 10 P.V.; however, the stabilization effect of limestone decreased with time. Moreover, the geochemical mobility of arsenic has transformed by increasing the mobile fractions in soil compared to initial soil. Therefore, based on the arsenic extraction results, the cultivation activities using phosphoric fertilizer could induce a decrease in the stabilization effect.