• Journal of the Korean GEO-environmental Society
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• v.9 no.5
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• pp.37-43
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• 2008

Inorganic injection material, which is one of the ground improvement materials, consists of cement accelerator and inorganic micro particle. The inorganic injection material is known to overcome the major limitations of water glass type improvement materials, which are leaching and accompanying strength loss. The inorganic injection material is superior in durability and strength, and environmentally friendly since leaching is prevented. In this study, the effectiveness and environment-friendliness of the MIS(Micro Injection-process System) using the inorganic injection material is compared to SGR, which uses the water glass. The performed tests were unconfined compression test, chemical resistance test, and fish poison test. The unconfined compression tests showed that the MIS results in 1.7 times higher 28 day strength compared to the SGR. In addition, the strength continually increased with time for the MIS, while it decreased for the SGR. The chemical resistance tests indicated that the rate of change in length using the MIS is 10~25 times smaller than when using the SGR. The fish poison test proved that MIS was more environmentally friendly. The analysis of chemical ingredients of leached showed that the amount of $Cr^{6+}$, Pb and Si leached from the MIS is less compared to the SGR. Accordingly, the MIS grout is more high-strength than existing SGR grout. It is excellent in shortening of construction period, structural stability of foundation and environmentally friendly. So, it is considered that it has not little the problem about groundwater pollution.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.3
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• pp.325-332
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• 2006

Statement of problem. Primary implant stability has long been identified as a prerequisite to achieve osseointegration. So the application of a simple, clinically applicable noninvasive test to assess implant stability and osseiointegratation are considered highly desirable. Purpose. The purpose of this study was to evaluate the ISQ value and the insertion torque of the 3 different implant system, then to evaluate whether there was a correlation between ISQ value and insertion torque; and to determine whether implant design has an influence on either insertion torque or ISQ value. Material and method. The experiment was composed of 3 groups: depending on the implant fixture design. Group1 was Branemark type parallel implant in $3.75{\times}7mm$. Group2 was Oneplant type straight implant in $4.3{\times}8.5mm$. Group3 was Oneplant type tapered implant in $4.3{\times}8.5mm$. Depending on the density of the bone, 2 types of bone were used in this experiment. Type I bone represented for cortical bone, type II bone represented for cancellous bone. With the insertion of the implant in type I and type II bone, the insertion torque was measured, then the ISQ value was evaluated, and then the correlation between insertion torque and ISQ value was analyzed Result and conclusion. Within the limitations of this study, the following conclusions were drawn. 1. Within the 3 different implants, the insertion torque value and ISQ value were higher in type I bone, when compared with type II bone.(p<0.05) 2. In type I and type II bone, Oneplant type tapered implant has the highest value in insertion torque.(p<0.05) 3. In type I and type II bone, there was no difference in ISQ values among the 3 types of implant. (p>0.05) 4. Significant linear correlation was found in $Br{\aa}nemark$ type parallel implant: $3.75{\times}7mm$ in type II bone.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.1
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• pp.15-29
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• 2005

Statement of problem. The adjustable dental impression trays were made for being adjusted their width automatically along the width of dental arch. Purpose. The purpose of this study was to investigate the best retentive form of adjustable dental impression tray, and so to make it a more satisfactory product. Material and methods. The eight pairs of adjustable trays were made of ABS(acrylonitrile butadiene styrene) with different distribution of holes and with or without the rim on the border area of them. The experiment was done with the horse-shoe shaped metal plate to pull out the set impression body from the tray, and the tray jig which was made for holding the tray on a lower part of Universal Testing Machine(UTM, Zwick Z020, Zwick Co., Germany). After the impression in the tray was allowed to set four minutes, a tensile force was applied at right angles to the tray which had been previously seated on the jig. The force was applied to measure a maximum retentive force by use of a UTM at a constant strain rate of 100mm per minute. A 2-factor analysis of variance (p<.05) was used to determine whether differences existed among distribution of retentive holes and between rim existing and not. Results. 1 The retentive force of the upper and lower resin tray with 2mm holes on the tray border was highest(25.83/24.98kg). (p<.05) 2. As the tray had more retentive holes, it was less retentive. 3. There was no significant difference in the retentive force of the varied hole intervals in the case of distributing all the area. (p>.05) 4. The rimless trays were more retentive generally, than the rimmed trays except 2 case: upper tray group-all area / 2 mm, intervals and lower tray group-margin only / 2 mm, intervals.(p<.05) 5. Most of the adjustable trays were showed higher retentive force than perforated metal tray except the lower group that perforated on the all area at intervals of 2 mm.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.1
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• pp.51-57
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• 2012

The anterior maxillary incisor is the most traumatized region in the mouth and trauma is frequent between the ages of 8-10. Traumatic loss of teeth, can lead to many complications in children. Thus, as possible to keep traumatic teeth, but if you need extractions There may be. Complications occur and early tooth loss is frequent. Complications of early loss of central incisors are esthetic compromise, loss of vertical and horizontal width, height, contour of alveolar bone, tilting of adjacent teeth, arch length loss. Alveolar bone loss may affect normal function and stability, and results in esthetic problem for future prosthesis restoration. The 9-year-old girl and 6-year-old boy got early loss of upper central incisor. The amount of alveolar bone resorption was measured using cone beam computed tomograph and cast analysis.

• Korean Journal of Occupational Health Nursing
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• v.4
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• pp.84-101
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• 1995

The periodic health examination have been shown the important role on early detection, early treatment and prevention of disease. Until now, there have been many studies that showed the effectiveness of the periodic health examination on the early detection and early treatment of disease to some extent. But there are few studies about primary prevention before health problem arise. In this case-control study, 29 newly detected hypertensive cases, 31 liver disease cases and 65 controls which are all available for 6-year data in the periodic health examination of a occupational field were compared to investigate the significant increase trend of health status between the groups. The results will be used for the occupational health nurses to provide appropriate primary prevention to the employees. The hypertensive and liver disease cases were divided observation-needed group and treatment-needed group. The data on systolic blood pressure, diastolic blood pressure, Body Mass Index and Broca Index in hypertensive cases and SGOT, SGPT, Body Mass Index and Broca Index in liver disease cases were analyzed by t-test and ANOVA. The specific findings are summarized as follows. 1. In the comparison between the hypertensive cases and controls, SBP and DBP of the observation-needed group and the treatment-needed group were significantly higher than the data of the controls for past 6 years. It was 2-3 years ago showing increase over 140/90mmHg of blood pressure in the hypertensive cases before they are categorized as hypertensive cases. In the observation-needed group and the treatment-needed group, the trend of the blood pressure for 6 years were significantly higher than the one of the controls. 2. In the comparison between the liver disease cases and controls, SGOT and SGPT of the observation-needed group and the treatment-needed group were significantly higher than the data of the controls for past 6 years. It was 2 years ago showing increase within upper normal limit of SGOT and 5 years ago of SGPT in the liver disease cases before they are categorized as liver disease cases. In the observation-needed group and the treatment-needed group, the trend of the liver enzyme for 6 years were significantly higher than the one of the controls. With these results, the author proposed that intervention for the primary prevention such as continuous follow-up, health education and weight control to the population who has over 140/90mmHg of blood pressure and upper normal limit of AST and ALT.

• Survey Research
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• v.9 no.2
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• pp.1-27
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• 2008

Problems of incomplete data are pervasive in statistical analysis. In particular, incomplete data have been an important challenge in repeated measures studies. The objective of this study is to give a brief introduction to missing data mechanisms and conventional/recent missing data methods and to assess the performance of various missing data methods under ignorable and non-ignorable missingness mechanisms. Given the inadequate attention to longitudinal studies with missing data, this study applied recent advances in missing data methods to repeated measures models and investigated the performance of various missing data methods, such as FIML (Full Information Maximum Likelihood Estimation) and MICE(Multivariate Imputation by Chained Equations), under MCAR, MAR, and MNAR mechanisms. Overall, the results showed that listwise deletion and mean imputation performed poorly compared to other recommended missing data procedures. The better performance of EM, FIML, and MICE was more noticeable under MAR compared to MCAR. With the non-ignorable missing data, this study showed that missing data methods did not perform well. In particular, this problem was noticeable in slope-related estimates. Therefore, this study suggests that if missing data are suspected to be non-ignorable, developmental research may underestimate true rates of change over the life course. This study also suggests that bias from non-ignorable missing data can be substantially reduced by considering rich information from variables related to missingness.

• Korean Journal of Social Welfare
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• v.35
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• pp.427-451
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• 1998

The purpose of this study is (1) to contrast the welfare state formation in Korea with that in Western European nations, and (2) to examine the historical peculiarities of the Korean welfare state formation process. For the analysis, this study uses' contrast of context' logic of comparative history and contrast the process of (1)modern state formation (2) civil society development (3) interventionist state evolution of Korea with those of Western European nations. The findings of this study are as follows: First, the distingushing role of nation state as welfare provider is very different. It is attributed to the difference in the traditional dominance structure and in the nation-bulding process of each case. Second, class cleavage of the Western Eeuropean nations has been continually mobilized for political action and converted into political resources, while it is impossible to achieve such results in Korea which has continued labor excusive regime. Third, the institutionalization patterns of welfare politics are different. In Western Eeuropean nations, public welfare benefits have been able to produce welfare coalitions and politics of solidarity. By contrast, since welfare have been thoroughly depoliticized and informalized in Korea, voters and political parties have not been able to make issues of welfare problem Due to these historical peculiarities, it seems to be impossible that Korea's underdeveloped public welfare could be changeable in near future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.366-373
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• 2020

This study explored the factors associated with dependence among smartphone-dependent adults in their 20s. The data was derived from the 2017 survey on smartphone over-dependence conducted by the Ministry of Science and ICT and the National Information Society Agency. The participants were 879 adults in their 20s. The data was analyzed by frequencies, percentages, means, standard deviations, independent t-tests, Pearson's correlation coefficients, and multiple regression analysis. The results revealed instant messengers as the most used application by participants. Participants in the high risk category of dependence also used SNS (Social Networking Services), music, and games more than those in the potential risk category. The more serious the dependence, the greater the frequency of smartphone use (β=.16, p=.000), and use of games (β=.10, p=.028), webtoons (β=.14, p=.004), SNS (β=.09, p=.047), and financial transactions (β=.17, p=.000). They did not recognize their smartphone dependence when it was relatively low. However, when this became serious, they then realized that they depended on the smartphone more than others. That means that it is not easy for adults to recognize their smartphone dependence on their own. However, recognition of the problem is the first step for adults to solve their problems. A program that evaluates their problematic smartphone use should be installed and used on all smartphones.

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.389-395
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• 2015

Digital image provides many conveniences at the internet environment recently. A great number of applications, like Digital Library, Stock Image, Personal Image and Important Information, require the use of digital image. However it has fatal defect which is easy to be modified because digital image is only electronic file. Numerous digital image forgeries have become a serious problem due to the sophistication and accessibility of image editing software. Copy-Move forgery is the simplest type of forgery that involves copying portion of an image and paste it on different location within the image. There are many approaches to detect Copy-Move forgery, but all of them have their own limitations. In this paper, visual and invisible feature based forgery detection techniques are tested and analyzed. The analysis shows that pros and cons of these two techniques compensate each other. Therefore, a hybrid of visual based and invisible feature based forgery detection that combine the merits of both techniques is proposed. The experimental results show that the proposed algorithm has enhanced performance compared to individual techniques. Moreover, it provides more information about the forgery, like identifying copy and duplicate regions.

• Journal of The Korean Association For Science Education
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• v.38 no.5
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• pp.649-665
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• 2018

In this study, we extracted the core competencies of makers through the analysis of critical incident technique and behavioral event interview to explore the nature and attributes of maker education, and then we developed a maker competency model based on these core competencies. As a result, six competency groups and 23 sub-competencies were extracted. In other words, we were able to confirm the existence of integrated thinking competency group consisting of four competencies made up of 'analytic thinking', 'intuitive thinking', 'visual thinking', and 'empirical thinking' and that of collaborative competency group with four competencies of 'sharing', 'communication', 'conflict management', and 'scrupulosity'. In addition, we could also confirm the existence of making mind competency group, which is composed of four competencies namely 'interest in various areas', 'challenge consciousness', 'failure management', and 'pleasure of the making process'. We could also confirm that human-centered competence group consisting of two competencies of 'humanity' and 'user-oriented' and the problem-finding competence group consisting of two competencies of 'observation' and 'recognition of discomfort in daily life'. Lastly, the making practice competency group is composed of seven competencies: 'understanding making tool', 'understanding electricity', 'understanding programming', 'planning', 'hand knowledge', 'information search', and 'direct execution'. We discussed educational implications of these findings.