• The Journal of Advanced Prosthodontics
• /
• v.9 no.3
• /
• pp.176-181
• /
• 2017

PURPOSE. The purpose of this study was to evaluate the marginal and internal gaps of Ni-Cr and Co-Cr copings, fabricated using the dental ${\mu}-SLA$ system. MATERIALS AND METHODS. Ten study dies were made using a two-step silicone impression with a dental stone (type IV) from the master die of a tooth. Ni-Cr (NC group) and Co-Cr (CC group) alloy copings were designed using a dental scanner, CAD software, resin coping, and casting process. In addition, 10 Ni-Cr alloy copings were manufactured using the lost-wax technique (LW group). The marginal and internal gaps in the 3 groups were measured using a digital microscope ($160{\times}$) with the silicone replica technique, and the obtained data were analyzed using the non-parametric Kruskal-Wallis H test. Post-hoc comparisons were performed using Bonferroni-corrected Mann-Whitney U tests (${\alpha}=.05$). RESULTS. The mean (${\pm}$ standard deviation) values of the marginal, chamfer, axial wall, and occlusal gaps in the 3 groups were as follows: $81.5{\pm}73.8$, $98.1{\pm}76.1$, $87.1{\pm}44.8$, and $146.8{\pm}78.7{\mu}m$ in the LW group; $76.8{\pm}48.0$, $141.7{\pm}57.1$, $80.7{\pm}47.5$, and $194.69{\pm}63.8{\mu}m$ in the NC group; and $124.2{\pm}52.0$, $199.5{\pm}71.0$, $67.1{\pm}37.6$, and $244.5{\pm}58.9{\mu}m$ in the CC group. CONCLUSION. The marginal gap in the LW and NC groups were clinically acceptable. Further improvement is needed for CC group to be used clinical practice.

• Geomechanics and Engineering
• /
• v.15 no.5
• /
• pp.1113-1124
• /
• 2018

Geological dynamic hazards during deep coal mining are caused by the failure of a composite system consisting of the rock and coal layers, whereas the joint in coal affects the stability of the composite system. In this paper, the compression test simulations for the rock-coal combined body with single joint in coal were conducted using $PFC^{2D}$ software and especially the effects of joint length and joint angle on strength and failure characteristics in a rock-coal combined body were analyzed. The joint length and joint angle exhibit a deterioration effect on the strength and affect the failure modes. The deterioration effect of joint length of L on the strength can be neglected with a tiny variation at ${\alpha}$ of $0^{\circ}$ or $90^{\circ}$ between the loading direction and joint direction. While, the deterioration effect of L on strength are relatively large at ${\alpha}$ between $30^{\circ}$ and $60^{\circ}$. And the peak stress and peak strain decrease with the increase of L. Additionally, the deterioration effect of ${\alpha}$ on the strength becomes larger with the increase of L. With the increase of ${\alpha}$, the peak stress and peak strain first decrease and then increase, presenting "V-shaped" curves. And the peak stress and peak strain at ${\alpha}$ of $45^{\circ}$ are the smallest. Moreover, the failure mainly occurs within the coal and no apparent failure is observed for rock. At ${\alpha}$ between $30^{\circ}$ and $60^{\circ}$, the secondary shear cracks generated in or close to the joint tips, cause the structural instability failure of the combined body. Therefore, their failure models present as a shear failure along partial joint plane direction and partially cutting across the coal body or a shear failure along the joint plane direction. However, at ${\alpha}$ of $60^{\circ}$ and L of 10 mm, the "V-shaped" shear cracks cutting across the coal body cause its final failure. While crack nucleations at ${\alpha}$ of $0^{\circ}$ or $90^{\circ}$ are randomly distributed in the coal, the failure mode shows a V-shaped shear failure cutting across the coal body.

• Cartoon and Animation Studies
• /
• s.37
• /
• pp.491-508
• /
• 2014

As number of making 3D feature animation films is increasing, 3D production pipeline become more complicated and more artists are needed than before. Major studios in foreign countries, in burden of producing high quality films with limited amount of budget and time, have been handling such difficulties by hiring technical directors in each department such as animation, rigging, cloth hair, and effect. Technical director is new occupation which appears after trend of producing animation is changed from 2D to 3D. Importance of technical director is increasing in respect to studios' needs which are related to complication in production time, manpower, budget, and production pipeline. This research is based on the researcher's work experience as an animation TD at Walt Diseny Animation Studio and Sony Pictures Imageworks, interview with working professionals, and related books and thesis. It focuses on the role of animation technical director in Disney's 3D feature animation film from two perspectives, 'Designing Production Pipeline' and 'Analyzing Problem of Shot'. Animation technical directors design and test production pipeline so that they can detect and solve problems that may arise in production process as early as possible. They not only analyze numerous problems of characters or shots limited to animation department but also in other departments such as modeling, mapping, character rigging, cloth, hair, lighting, rendering, software development in order to support artists to complete their shots according to the production schedule. In accordance with recent trend of increasing number of 3D feature animation film production in South Korea and collaboration with foreign studios outside of South Korea, it is vital to train animation technical directors who can develop production pipeline, analyze various problems of shots and characters to escalate efficiency in production.

• Journal of dental hygiene science
• /
• v.15 no.5
• /
• pp.536-541
• /
• 2015

The purpose of this study was to evaluate the marginal and internal gap of Cobalt (Co)-Chromium (Cr) sintering metal coping fabricated by dental computer-aided design/computer-aided manufacturing systems. Abutment tooth 46 of universal numbering system was selected for the study. Twenty Co-Cr metal copings of two groups were manufactured and scanned. Co-Cr cast metal copings (CCM) group of ten were fabricated using investment, burnout and casing after subtractive manufacturing of wax block. Also, Co-Cr sintering metal copings (CSM) group of ten were fabricated using sintering processing after subtractive manufacturing of Co-Cr soft metal bock. Marginal and internal gap of Co-Cr metal copings of twenty were measured by digital microscope (${\times}160$) with silicone replica technique. The data was analyzed from IBM SPSS Statistics ver. 22.0 Statistical software for Mann-Whitney U test (${\alpha}=0.05$). $Mean{\pm}standard$ deviation of marginal gap of CCM group was $90.12{\pm}61.73{\mu}m$ of CSM group was $60.17{\pm}24.83{\mu}m$. However, two groups was statistically not different (p>0.05). This study showed that CSM group was clinically acceptable adaptation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.6
• /
• pp.1-8
• /
• 2016

Current sensors are used widely in the fields of current control, monitoring, and measuring. They have become more popular with the increasing demand for smart grids in a power network, generation of renewable energy, electric cars, and hybrid cars. Although open loop Hall effect current sensors have merits, such as low cost, small size, and weight, they have low accuracy. This paper describes the design and fabrication of a 300A open loop current sensor that has high accuracy and temperature performance. The core of the current sensor was calculated numerically and the signal conditioning circuits were designed using circuit analysis software. The characteristics of the manufactured open loop current sensor of 300 A class was measured at currents up to 300 A. According to the test of the current sensor, the accuracy error and linearity error were 0.75% and 0.19%, respectively. When the temperature compensation was carried out with the relevant circuit, the temperature coefficients were less than $0.012%/^{\circ}C$ at temperatures between $-25^{\circ}C$ and $85^{\circ}C$.

• KIPS Transactions on Software and Data Engineering
• /
• v.7 no.8
• /
• pp.287-296
• /
• 2018

In the recent commercial DBMS market, as the users' burden and complaint which are related to high price licensing policy and late technical support service are increasingly rising, the concern for use of open source DBMS which has no problem with compatibility or stability is escalating. Due to the fact, the cases saving the cost are growing by converting Oracle Corporation's applications, which has about 60% share in the DBMS market, to an open source DBMS. However, in converting non-interchange sentences to an ANSI standard-based open source DBMS because of the use of PL/SQL in Oracle Corporation provides, a lot of manual work accompanies, so there is a lot of loss of time and money. Therefore, a tool that automatically converts PL/SQL to standard SQL is required. The proposed automation tool for the conversion of applications converts PL/SQL to Java Stored Procedure, an open source DBMS-based ANSI standard programming language. Through carrying out a test on the automation tool, it is proved that the tool will contribute to shortening time and saving cost by verifying the identity of input-output data and its reliability after correcting errors in converting to Java Stored Procedure.

• The korean journal of orthodontics
• /
• v.35 no.3 s.110
• /
• pp.163-173
• /
• 2005

The purpose of this study was to compare the asymmetric degree between maxillofacial hard and soft tissues in individuals with facial asymmetry. Computerized tomographies (CT) of 34 adults (17 male, 17 female) who had facial asymmetry were taken. The CT images were transmitted to personal computers and then reconstructed into three-dimensional (3D) images through the use of computer software. In order to evaluate the degree of facial asymmetry, 6 measurements were constructed as the hard tissue measurements while 6 counterpart measurements were taken as the soft tissue measurements. The means and standard deviations were obtained for each measurement using 3D measure, then t-test was used to investigate the differences between each hard tissue measurement and the corresponding soft tissue measurement All measurements used in the present study showed statistically significant differences between the hard and soft tissues. The degree of soft tissue asymmetry was smaller than that of corresponding hard tissue asymmetry in case of chin deviation, frontal ramal inclination difference, and frontal corpus inclination difference. On the other hand, the degree of soft tissue asymmetry was greater than that of underlying hard tissue asymmetry in the measurement of lip canting and lip cheilion height difference The present study suggests that asymmetric differences of hard and soft tissue is observed nu facial asymmetric subjects and thus soft tissue analysis is needed in addition to hard tissue analysis when making an evaluation of facial asymmetry.

• The Journal of Korean Academy of Prosthodontics
• /
• v.31 no.4
• /
• pp.625-642
• /
• 1993

Whether stress-absorbing elements are functional in an implant system has been an issue of interest in oral implantology. The unique feature of the IMZ implant system is the planned imitation of the stress-distributing function of the structural unit of the tooth, periodontium, and alveolar bone through the use of an intramobile element(IME). The purpose of this study was to compare the difference in the displacement and the stress distibutions of IMZ implant with a polyoxymethylene(POM) or a titanium IME under static load. Two dimensional finite element analysis(FEA) was applied for this study and two finite element models were created. PATRAN program(DPA Co.,USA), a software for FEA, and SUN-SPARC2GX(SUN Co., USA), a workstation computer, were used. $1Kg/mm^2$ of static load was loaded individually on each three point of crown of implant prosthesis ; central fossa(load 1), mesial cusp tip(load 2), distal cusp tip(load 3), The displacements of X- and Y-axis and total displacement were measured at mesial and distal cusp tips, mesial and distal points between crown and IME, and implant apex. The von Mises stress was measured at mesial and distal points between crown and IME, mesial and distal points between IME and TIE, mesial and distal alveolar crest, the mesial and distal midpoints of implant, and implant apex. The difference in resultant values were compared and evaluated statistically using paired t-test. The results were as follows : 1. Under the load 1, all the displacement of implant with titanium IME at 5 measuring points was larger than that of with POM IME except total and Y-axis displacement at implant apex. And the differences in stress distributions with POM and titanium were varied. 2. Under the load 2, all the displacement of implant with titanium IME at 5 measuring points was larger than that of with POM IME except X-axis displacement at distal cusp tip. And the differences in stress distributions were varied. 3. Under the load 3, all the displacement of implant with titanium IME at 5 measuring points was larger than that of with POM IME except Y-axis displacement at mesial cusp tip. And the differences in stress distributions were varied. 4. For the displacement, there was significant difference statistically only in total displacement (P<0.1), but was no significant difference in X- and Y-axis displacement(P>0.1). For the stress, there was no significant difference among the compared values.

• Journal of The Korean Association of Information Education
• /
• v.21 no.4
• /
• pp.415-424
• /
• 2017

Due to the influence of the fourth industrial revolution in recent years, maker education is getting attention. Therefore, this study tried to propose the possibility of application (app) development education as maker education by empirically verifying the affective and cognitive effects of app development education using authoring tool. To do this, we implemented app development education in D high school in Seoul, Korea, and collected data from 41 participants. We analyzed the changes in attitudes toward SW education and creative problem-solving ability before and after the education by conducting the paired t-test, and the level of satisfaction and perceived achievement through descriptive statistics analysis. Also, the learner's responses collected through the open-ended questionnaire were analyzed qualitatively. The result showed that the attitude toward SW education and creative problem-solving ability showed statistically significant improvement after app development education using the authoring tool, and the learner's statement also supported this result. Also, satisfaction and perceived achievement after the education were relatively high. Through these results, we have empirically confirmed the effect of app development education using the authoring tool for high school students, and derived the theoretical and practical implications.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.35 no.5
• /
• pp.302-309
• /
• 2013

Purpose: This study evaluated the prognosis of conservative and surgical treatment according to the staging of bisphosphonate-related osteonecrosis of jaw (BRONJ) by American Association of Oral and Maxillofacial Surgeons and American Society for Bone and Mineral Research. Methods: We evaluated 53 patients of BRONJ who visited Department of Dentistry, Ajou University School of Medicine from May 2007 to February 2013. Twenty eight patients in stage 2, were divided into surgical and conservative groups with cessation of bisphosphonate therapy. Fifteen patients belonged to the conservative treatment group, in which mouth rinsing and antibiotics medication were done. Thirteen patients were treated with debridement or sequestrectomy, in the surgical treatment group. Each study list was analyzed by SPSS ver. 14.0 (SPSS Inc., USA) software and the favorable rate was verified by the Fisher exact test. P-values less than 0.05% were deemed significant. Results: Clinical outcome was evaluated on the basis of both clinical and radiographic findings. Of all the 28 patients of stage 2, 15 patients underwent conservative treatment and 13 patients received surgical treatment. In the surgical group, 9 of 13 (69.2%) showed good prognosis, 4 of 13 (30.7%) showed recurrence. In the conservative group, 13 of 15 (86.6%) showed no change duting the follow-up period. Two of 15 patients even showed a bad prognosis, such as pain and pus discharge, which are criteria for stage 3. P-value was 0.067 (>0.05). Conclusion: The results of the present study suggests that surgical intervention is good choice against the conservative treatment, after proper drug holidays period, while further investigation is needed for a definite solution to BRONJ.