• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.4
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• pp.277-288
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• 2002

Seven finite element models were constructed in mandible having single screw-type implant fixture connected to the premolar superstructure, in order to evaluate how the length, diameter and platform shape of a screw-type fixture influence the stress in the supporting tissue around fixtures. Each finite element model was varied in terms of length, diameter, and platform shape of the fixture. In each model, 250N of vertical load was placed on the central pit of an occlusal plane and 250N of oblique load placed on the buccal cusp. The stress distribution in the supporting tissue and the other components was analysed using 2-dimensional finite element analysis and the maximum von Mises stress in each reference area was compared. Under lateral loading, the stress was larger at the abutment/fixture interface, and in the crestal bone, compared to the stress pattern under vertical loading. The amount of stress at the superstructure was similar regardless of the length, diameter and platform shape of a fixture. Around the longer fixture, the stress was decreased at the bone crest and subjacent cancellous bone and increased in the cancellous bone area apical to the fixture. Around the wider fixture, the stress was decreased at the abutment/fixture interface, and the bone crest and increased in the cancellous bone area apical to the fixture. Around the fixture having wider platform, less stress was produced at the abutment/fixture interface and the upper part of the cortical bone, compared to the fixture having standard platform. In conclusion, the stress distribution of the supporting tissue was affected by length, diameter, and platform shape of a fixture, and the fixture which was larger in diameter and length could reduce the stress in the supporting tissues at the bone-fixture interface and bone crest area.

• Journal of Korean Society of Rural Planning
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• v.4 no.1
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• pp.98-107
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• 1998

For efficient development of rural facilities, choice of their optimum locations would be an important issue, however, existing research works concentrated much more an allocation policy of urban industrial complex and public facilities than rural ones. In this study, because agricultural-cum-industrial complex has been the most widely developed representative one of rural facilities, it was selected as a case study facility. As a pre-study to system development, existing governmental location-decision system was checked and interviewing survey carried out to find out on-spot problems. And, being based on literature review and survey analysis results, 4-step optimum locational decision model was developed , formulation of locational goal system, ranking tabulation on components, determination of significance values of components, calculation of component scores. Finally, through the case study works on 3 sites, system applicability was checked, Considering together the simplicity problem of existing guidelines and the interviewing survey results favoring the diversified viewpoints, it would be necessary to develop multifaceted support system for locational decision making. 3-tier classification steps from the higher, middle to lower one were used and their underpinning viewpoints were sorted as on regional development, entrepreneurship, spatial rationality, from which a tentative locational goal system was formulated. Through the expert group checking, final locational goal system was determined having 3 of the higher classification items, 7 of the middle ones, 23 of the lower ogles. For ranking tabulation, 3 types of ranking criteria were arranged which were based on statistical analysis using mean and standard deviation(Type I ), its existence or not 1 good or not(Type E ), and the others(Type E ). From the significance evaluation results, regional development and entrepreneurship aspects were valued much higher than spatial rationality aspect. And, in the middle step, items as spread effects of regional economy, accessibility and social potentialities were highly valued while infrastructural development level and natural condition being low. The application results of the system to 3 case study total. However, the detailed ones differed among study the influencing effects on regional economy, and contrast greater the infrastructural development level. Conclusively, final evaluation values well represented the characteristics of each area. If this system be complemented and applied comprehensively by the successive studies, it would be developed to a general model of locational decision supporting system for rural facilities.

• Journal of the Korean Society for Library and Information Science
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• v.11
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• pp.3-42
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• 1984

This is to establish a model of the standardization of shelving, chairs, tables and card cabinets for college and university libraries in Korea. The size of furniture was measured on the base of the analysis of the human factors, such as the standard size of human bodies of the college students in Korea, the scope of work area, the moving degree of muscles, the limit of the visual field, etc. The results of this study are as follows: 1. It is desirable that the standard shelf length should be 800mm. and the maximum . shelving height should not exceed 1,803mm. And it is desirable that the bottom shelf has a ground clearance of about $210\~390mm$. 2. It is advisable that the sloped shelving has the slope from about 1,000mm, or 930mm, and the gradient should be $19^{\circ}$ from the above mentioned sloping position and the bottom of each shelf. And it is desirable that the slope height of each shelf should be 77mm. 3. It is advisable that the seat area for users should be $410\~420\times420mm$, and the seat height should be $390\~0400mm$. 4. It is desirable that the table size per user should exceed $490\times880\~890mm$, and the table height should be $680\~690mm$. 5. It is advisable that each tray of the card cabinet should hold about 740 cards, and the depth should exceed 430mm. And it is desirable that the maximum height of card cabinets should be as follows: 60du(drawer units)-$1,400\~1,460mm$, 30du-1, 300mm, 15du-1,100mm. In addition, it is advisable that the 30du cabinet should accomodate 5 trays vertically and 6 trays horizontally for avoiding the worst working position rather than 6 trays vertically and 5 trays horizontally. 6. It is desirable that the height of sliding reference shelves in card cabinets, or consultation tables should be 900mm. But in the case of the sliding shelves, it is desirable to be as follows: 15du-900mm when the card cabinet height is more than 1,100, mm, but unnecessary when less than 1,100mm high, 30du-1,000mm, or 1,100mm in the case of $5\times6du$, but 900mm in the case of $6\times5du$, $60du-900\~950mm$ when the card cabinet height is $1,400\~1,460mm$.

• Journal of dental hygiene science
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• v.14 no.2
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• pp.94-100
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• 2014

The purpose of this study was to evaluate the accuracy of digitized elastomeric impression materials of crown abutment, using non-contact white light scanner and virtual three-dimensional superimpositional analysis. The stone models and impressions were digitized white light scanner to create three-dimensional surface models. Stone models were used as CAD reference model (CRM). The resulting point clouds (ASC file) from digitization of impressions using converting software. Discrepancies between the points in the point clouds and CRM were measured by superimpositional software. Mean and standard deviation of values of discrepancies were analyzed by one-way ANOVA and multiple comparison (${\alpha}=0.05$). The mean discrepancy between the impressions for the extra-light body (XLB), light body (LB), and heavy body (HB) group were $5.10{\pm}1.45{\mu}m$, $6.30{\pm}1.87{\mu}m$, $9.80{\pm}1.52{\mu}m$, respectively. The different impression materials affected the digitization of impressions significantly (p<0.05). As a result, digitization of elastomeric impression materials on dental scanner was influenced by material sort.

• Journal of Radiation Protection and Research
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• v.10 no.1
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• pp.50-63
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• 1985

A derivation of new release limit, named Derived Release Limit(DRL), into the atomsphere from a reference nuclear power plant has been performed on the basis of the new system of dose limitation recommended by the ICRP, instead of the (MPC)a limit which has been currently used until now as a general standard for radioactive effluents in Korea. In DRL Calculation, a Concentration Factor Method was applied, in which the concentrations of long-term routinely released radionuclides were in equilibrium with dose in environment under the steady state condition. The analytical model used in the exposure pathway analysis was the one which has been suggested by the USNRC and the exposure limits applied in this analysis were those recommended by the USEPA lately. In the exposure pathway analysis, all of the pathways are not considered and some may be excluded either because they are not applicable or their contribution to the exposure is insignificant compared with other pathways. In case, the environmental model developed in this study was applied to the Kori nuclear power plant as the reference power plant, the highest DRL value was calculated to be as $9.10{\times}10^6Ci/yr$ for Kr-85 in external whole body exposure from the semi-infinite radioactive cloud, while the lowest DRL value was observed 3.64Ci/yr for Co-60 in external whole body exposure from the contaminated ground, by the radioactive particulates. The most critical exposure pathway to an individual in the unrestricted area of interest (Kilchun-Ri, 1.3 km to the north of the release point) seems to be the exposure pathway from the contaminated ground and the most critical radionuclide in all pathways appears to be Co-60 in the same pathway. When comparing the actual release rate from KNU-l in 1982 with the DRL's obtained here the release of radionuclides from KNU-1 were much lower than the DRL's and it could be conclued that the exposure to an individual had been kept below the exposure limits recommended by the USEPA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.743-751
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• 2016

It is critical to effectively change the measures of prevention from the breakdown maintenance proceeding an apartment housing maintenance task scope. It is necessary that systematization be performed for a series of tasks, such as facility inspection, diagnosis and replacement. In addition, it is preceded by establishing a standardization for maintenance work scope. Therefore, this study examined the problems related to public rental housing maintenance work scope to manage it more systematically. In addition, the study suggests a work process section for facility repairs, long term replacement and general maintenance using one on one interviews with experts to classify the occupants, management office and head office. This study's standard work system is expected to provide fairness and transparency in addition to improving the productivity in public rental housing maintenance via an efficiency promotion plan. In addition, it is used as the basic reference for developing a system of public rental housing maintenance costs and diagnosis actions. Finally, it is necessary to create improvements that provide a more objective work system standardization throughout the analysis of the productivity data according to the work flow and the review of the occupants, management office and head office in the future applications of the pilot site.

• Journal of Broadcast Engineering
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• v.24 no.6
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• pp.1035-1052
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• 2019

Recently, as the demand for immersive videos increases, efficient video processing techniques for omnidirectional immersive video is actively developed by MPEG-I. While the omnidirectional video provides a larger degree of freedom for a free viewpoint, the size of the video increases significantly. Furthermore, in order to compress 6 degree-of-freedom (6 DoF) videos that support motion parallax, it is required to develop a codec to yield better coding efficiency. In this paper, we develop a 6 DoF codec using Versatile Video Coding (VVC) as the next generation video coding standard. To the authors' best knowledge, this is the first VVC-based 6 DoF video codec toward the future ISO/IEC 23090 Part 7 (Metadata for Immersive Media (Video)) MPEG-I standardization. The experiments were conducted on the seven test video sequences specified in Common Test Condition (CTC) in two operation modes of TMIV (Test Model for Immersive Media) software. It is demonstrated that the proposed codec improves coding performance around 33.8% BD-rate reduction in the MIV (Metadata for Immersive Video) mode and 30.2% BD-rate reduction in the MIV view mode as compared to the state-of-the-art TMIV reference software. We also show the performance comparisons using Immersive Video PSNR (IV-PSNR) and Mean Structural Similarity (MSSIM).

• Journal of Periodontal and Implant Science
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• v.49 no.5
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• pp.299-309
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• 2019

Purpose: To analyze the ridge profile of the anterior maxilla using cone-beam computed tomography and to assess the clinical significance of the ridge profile by performing virtual implant placement. Methods: Thirty-two cone-beam computed tomography scans of anterior maxillae were included. For each tooth, a vertical line was made along the longitudinal axis, and 3 horizontal lines at 1-, 3-, and 5-mm levels below the labial bone crest were drawn perpendicularly to the vertical reference. At these levels, the thickness of the alveolar ridge (RT), and the labial (LT) and palatal bone plate (PT) were measured. Then, virtual implant placement using standard and tapered implants was performed. A generalized linear mixed model was used for statistical analysis. Results: The teeth were located labially based on the proportion of LT and PT with respect to RT. At the 1-mm level, the value of LT was between $1.0{\pm}0.4mm$ for central incisors and $1.3{\pm}0.6mm$ for canines. A large number of teeth had area(s) with less than 1-mm-thick labial bone between the 1- and 5-mm levels below the crest. The mean PT was generally thicker than the LT in all tooth types. The greatest mean value of labial concavity was observed for canines, compared to other tooth types. Men had a greater RT than did women, but had a comparable LT. Less apical fenestration was observed when tapered implants were used. Conclusions: Most teeth in the anterior maxilla had a thin labial bone plate, with no significant difference between sexes. Tapered implants may be advantageous for the anterior maxilla.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.2 no.1
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• pp.178-210
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• 1974

It needs to put into practice the systems analysis in the analysis of some operations and status of library for the purpose of systematizing the work of reforming in the new easier form to process, to storage, to retrieve and to make use of the increasing informations and data of library. In this study, some of systems which are generally using in every library was caught in the case study of K university library. Having analyzed them with the two methods of the flowcharting and mathematical analysis, we found the obstructive factors in operation. As the result of this research, it was gained the new system as the alternative one. A. Alternative System B. Advantages of alternative systems 1. In the reference room When it converts the present system into the new system, it can profit 6.771 won/user (13.815won-7.044won=6.771 won). Therefore, a half the average required cost of the present system can be saved. If this saving would be alloted for the cost 33,000won required to make the cataloging cards, it would be taken for 94 days (33,000 won ${\div}$ 6,771 won/user=4,874users. 4,874users ${\div}$ 52users/day=94days) to get it. The saving cost/year by the new system will be 95,417 won, and in the first year the initial cost (33,000won) reduces the saving cost to 62,417won. 2. In the periodical room The average required time for using the materials of the present system is 17 minutes/user and the average required cost/user is 23.775won, while the average required time of the new system is 4 minutes and the average required cost/user is 5.33won. Therefore, the new system has profit 4 times of the present system. Accordingly, it occurs when the dispersed periodical materials get together. 3. In the classification and cataloging When one processes - the oriental books - by the Linear Programming Technique, the maximum of the process can be increased from 11.6 volumes per librarian of the present system to 12 volumes per librarian of the new system increased 0.4 volume in a day, and cataloging by the manual printer can be shorten from 3 minutes per card of the present system to 1.5 minutes per card of the new system. Consequently, we can complete the other operations (books equipment, updating of cataloging cards, etc.) with 141 minutes which are saved in the course of the afore-mentioned works. 4. In the status of collections The average growth rate of 4 years from 1968 to 1971 is 9.825 %, and that of the purchased materials is 6.2% similar to the advanced nations, but it has the different position from 215,000 volumes by the Standard Degree for Establishment of College and University, and the difference between the total collections 151,671 volumes and Dunns' growth model ($N_t=N_oe^{-at}$) claimed by Leimkuhler 155,297 volumes in 1971 is 3,626 volumes, and for the purpose of compensation the difference, we found the fact that it needs to have the increased budget of 24~30% per year, Thus, if the budget of 24~30 % per year. Thus, if the budget would be increased per year as the rate of the afore-mentioned figure, it would be reached at the Standard Degree for Establishment of College and University in 1975, and thereafter, it can be decreased to the lebel which is able to maintain the growth rate of 5~6% per year.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.316-323
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• 2011

Purpose: The purpose of this study was to investigate the effect of different thread designs on the marginal bone stresses around dental implant. Materials and methods: Standard ITI implant(ITI Dental Implant System; Straumann AG, Waldenburg, Switzerland), 4.1 mm in diameter and 10 mm in length, was selected as control. Test implants of four different thread patterns were created based on control implant, i.e. maintaining all geometrical design of control implant except thread pattern. Four thread designs used in test implants include (1) small V-shape screw (model A), (2) large V-shape screw (model B), (3) buttress screw (model C), and (4) trapezoid screw (model D). Surface area for unit length of implant was 14.4 $mm^2$ (control), 21.7 (small V-shape screw), 20.6 (large V-shape screw), 17.0 (buttress screw) and 28.7 $mm^2$ (trapezoid screw). Finite element models of implant/bone complex were created using an axisymmetric scheme with the use of NISA II/DISPLAY III (Engineering Mechanics Research Corporation, Troy, MI, USA). A load of 100 N applied to the central node on the crown top either in parallel direction or at 30 degree to the implant axis (in order to apply non-axial load to the implant NKTP type 34 element was employed). Quantification and comparison of the peak stress in the marginal bone of each implant model was made using a series of regression analyses based on the stress data calculated at the 5 reference points which were set at 0.2, 0.4, 0.6, 0.8 and 1.0 mm from implant wall on the marginal bone surface. Results: Results showed that although severe stress concentration on the marginal bone cannot be avoided a substantial reduction in the peak stress is achievable using different thread design. The peak marginal bone stresses under vertical loading condition were 7.84, 6.45, 5.96, 6.85, 5.39 MPa for control and model A, B, C and D, respectively. And 29.18, 26.45, 25.12, 27.37, 23.58 MPa when subject to inclined loading. Conclusion: It was concluded that the thread design is an important influential factor to the marginal bone stresses.