• Imaging Science in Dentistry
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• v.42 no.3
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• pp.139-146
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• 2012

Purpose: An individual surgical stent fabricated from computed tomography (CT) data, called a CT-guided stent, would be useful for accurate installation of implants. The purpose of the present study was to introduce a newly developed CT-guided stent with a simple design and evaluate the accuracy of the stent placement. Materials and Methods: A resin template was fabricated from a hog mandible and a specially designed plastic plate, with 4 metal balls inserted in it for radiographic recognition, was attached to the occlusal surface of the template. With the surgical stent applied, CT images were taken, and virtual implants were placed using software. The spatial positions of the virtually positioned implants were acquired and implant guiding holes were drilled into the surgical stent using a specially designed 5-axis drilling machine. The surgical stent was placed on the mandible and CT images were taken again. The discrepancy between the central axis of the drilled holes on the second CT images and the virtually installed implants on the first CT images was evaluated. Results: The deviation of the entry point and angulation of the central axis in the reference plane were $0.47{\pm}0.27$ mm, $0.57{\pm}0.23$ mm, and $0.64{\pm}0.16^{\circ}$, $0.57{\pm}0.15^{\circ}$, respectively. However, for the two different angulations in each group, the $20^{\circ}$ angulation showed a greater error in the deviation of the entry point than did the $10^{\circ}$ angulation. Conclusion: The CT-guided template proposed in this study was highly accurate. It could replace existing implant guide systems to reduce costs and effort.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.4
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• pp.526-552
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• 1994

The extent and direction of movement of removable partial dentures during function are influenced by the nature of the supporting structures and and the design of the prosthesis. Since forces are transmitted to the abutment teeth through occlusal rests, guide planes and direct retainers during functional movements, proper design based on the avaialble research data will maintain the health of abutment teeth and their supporting structures. The purpose of this in vitro study is evaluating stress distribution clinically around the abutment teeth prepared following 4-type clasping systems for unilateral free-end removable partial dentures. Three-Dimensional Photoelastic Stress Analysis method was used because it shows a visual display of stresses of the simulated abutment teeth and residual ridges and reveals stress concentration that can be read at any given points in terms of direction and magnitude. For this study, the author fabricated 4 mandibular photoelastic epoxy models missing left 1st and End molar. Epoxy models were duplicated and 4 unilateral removable partial dentures were construe- ted in accordance with 4-type direct retainers. Unilateral free-end removable partial dentures were positioned on their own models. 6kg force was loaded on the every removable partial dentures of the epoxy model on the central fossa of mandibular left 1st molar vertically by the loading device. After the stress was frozen in a stress freezing furnace, 6 specimens of 6-mm thickness were made from every epoxy model and examined with the circular polariscope. The results were as follows : 1. Generally I-bar clasp revealed the most favorable stress distribution around the abutment teeth. 2. At the end portion of the free-end ridge, Back action clasp showed the highest stress concentration at the bucco-lingual and top portions of the residual alveolar ridge. 3. At the distal area of the abutment teeth, Akers clasp and Roach clasp showed higher stress concentration bucco-lingually and apically than the others. 4. To the abutment tooth, I-bar clasp showed the least stress distribution bucco-lingually but the others showed irregular stress distribution. 5. At the mesial area of the abutment teeth, the order of effective stress distribution was I-bar clasp, Back-action clasp, Akers clasp and Roach clasp. There was big difference of stress distribution between them. 6. At the right 2nd premolar and 1st molar, the stress concentration of Akers clasp was a little high but that of I-bar clasp was low.

• Korean Institute of Interior Design Journal
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• v.14 no.4 s.51
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• pp.87-94
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• 2005

Lately due to the sudden growth of the construction of an apartment complex in domestic market, many construction companies are eager to provide various public facilities to increase the apartment distribution rate. An introduction of a fitness center is popularized as a part of such development. There has been a continuing development in a private fitness based on analyzing the user's data. However a public fitness is quite different from the private in terms of a user's classification, preference rate, the pattern of use, and location which requires a different facility plan. Nevertheless, all these days a public fitness in an apartment house has been developed without a specific facility plan based on relevant materials. It is worried that such development would cause the facilities not to function as appropriate resident facilities and sink to idle ones. Therefore the purpose of this paper is to make the standard considered in facility planning in future and the base to guide an applying method. In the paper the present condition of fitness centers inside apartment houses has been compared to analyze the progress of the existing facilities and the appropriateness of the organization and the structure division. The result of the research shows that public resident facilities is not the place to perform passive role for fixed activities but one to form a community through the human relationship based on the facility. Therefore a fitness center inside the apartment complex have to be designed to provide service and leisure space as one of main community facilities for residents. To obtain this purpose, when choosing facilities of an apartment complex, first of all the residents' standard of living, apartment size, residents' distinction rate of age and sex, the needs of the times should be fully considered Secondly, the size of each facility space have to be decided based on the practical data analysis in facility use such as space preference, average staying time. Also, future living culture requires the change of the function and space according to the change of social values, so continuing research and data analysis are required to related to fitness center inside an apartment complex in order to present systematic approaching method and the paper will be expected to be a little step toward it.

• The Journal of the Korea Contents Association
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• v.17 no.5
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• pp.552-564
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• 2017

This study is aimed to overcome the limitation of traditional learning competence and career management system, and conducted to design the function of integrated ePortfolio and the elements of the system for administrative control of curricular and extracurricular program of the university as well as to develop a printout-based prototype in the context of S-university. Researchers deducted the main menus and functions of the integrated ePortfolio by two experts validification procedures, searched for the subfunctions, and secured their validity. Mainly 6 elements of integrated ePortfolio system are designed as follows: basic information, learning and competence management, course and career management, portfolio management, and community. Among these, the three elements of learning and competence, course and career, and portfolio management are assessed as excellent and differentiated from traditional ePortfolios. The study also developed a printout-based prototype of ePortfolio system and provided authentic guide for the ePortfolio system. At the same time, the result of the study contributed to increasing the sense of the developmental direction of the ePortfolio in the institute.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.497-507
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• 2021

All-on-six concept can be used as one of the treatment options to maximize the use of available residual alveolar bone for implant-supported fixed prosthesis on edentulous patients. But this process is complex and cumbersome. Digital system can be used at multiple steps, from implantation to prosthetic restoration, to overcome this shortcoming. In this case of a maxillary edentulous patient aged 76, digital system was used for restoration of 1-piece design, screw retained fixed prosthesis from diagnosis, implant surgery to fabrication of provisional and final prosthesis. For preoperative diagnosis and treatment planning stage, intra-oral information of a patient was digitalized by direct intra-oral scan. Surgical guide and immediate provisional prosthesis was designed based on this digitalized data. Patient's inconvenience was minimized by applying immediate provisional prosthesis, which was delicately fabricated according to the location data of six implants on most suitable residual alveolar bone. Then, final prosthesis was designed and fabricated going through new interim prosthesis which was newly designed and fabricated, considering patient's requests, stable vertical dimension and occlusion, and esthetic factors using digital system. We hereby report a case successfully applying digital system to multiple steps including implant surgery to fabricating prosthesis, to simplify existing complicated implant treatment procedure to an edentulous patient.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.288-295
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• 2019

Passive fit of prosthesis is an essential property of implant supported prosthesis for long term success and minimization of complications. And the property is determined mostly by fabrication procedure. There were limitations of extensive implant prosthesis because conventional casting method generate contraction error of long span prosthesis. However, Computer-aided design/Computer-aided manufacturing (CAD/CAM) technology of 3D printing and milling metal framework can overcome those limitations. This case is a full mouth rehabilitation using extensive implant fixed prosthesis. Removable interim prosthesis was made for esthetic, functional evaluation and a guide for implant insertion. After the insertion, implant fixed interim prosthesis was delivered. After additional evaluation and adjustment, final prosthesis was designed with CAD, the fabricated with CAM. Milling technique was used for anterior screw type implant superstructure and 3D printing technique was used for the anterior and posterior implant copings. Fit of the final restoration was favorable. The practitioner and patient were both esthetically and functionally satisfied with the final result.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.694-701
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• 2018

Larger crack widths can be observed more in FRP-reinforced concrete members than in steel-reinforced concrete members as a result of the lower elastic modulus and bond strength of FRP reinforcement. The ACI 440.1R-15 design guide provides equations derived as the maximum bar spacing to control the crack widths indirectly. On the other hand, it is not concerned with long-term effects on the crack control design provisions. This study provides suggestions for how to incorporate time-dependent effects into the crack width equation. The work presented herein includes the results from 8 beams composed of four rectangular and T-shaped FRP-reinforced concrete beams tested for one year under four-point bending. Over a one year period, the crack widths increased as much as 2.6~3.0 times in GFRP and AFRP-reinforced specimens and 1.1~1.4 times in the CFRP-reinforced specimens compared to steel-reinforced specimens. In addition, the average multiple for crack width at one year relative to the instantaneous crack width upon the application of the sustained load was 2.4 in the specimens with a rectangular section and 3.1 in the specimens with a T-shaped section. As a result, it is recommended conservatively that the time-dependent coefficient be taken as 2.5 for the rectangular beams and 3.5 for T-beams.

• Journal of the Korean GEO-environmental Society
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• v.12 no.1
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• pp.81-87
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• 2011

The characteristics of vertical to horizontal ratio of response spectrum from 20 recent earthquakes were analysed. Response spectrum of 260 horizontal and 130 vertical ground motions were normalized by peak ground acceleration at each resonance frequency from 0.1 to 50Hz. It has been identified that the ratio of vertical to horizontal response spectrum has strong dependancy on epicentral distance and resonance frequency. The ratio of vertical to horizontal response spectrum for the 0-50km epicentral distance group are larger than 2/3 values, which is a standard engineering rule-of-thumb V/H=2/3, at resonance frequency above 7-8Hz. All the 3 groups such as 50-100, 100-150- and 150-200km epicentral distance have shown larger values of vertical to horizontal ratio than 2/3 at resonance frequency above 15Hz and also are larger than 2/3 at resonance frequency below 8-10Hz. Even though there are differences in specific resonance frequency values which depend on the epicentral distance group, we should be careful of seismic design of vertical component of the structures winch are located within the range of about 200km distance. form the potentially seismic causative faults.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.295-303
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• 2023

South Korea has recently witnessed an increasing number of seismic events, leading to a surge in studies focusing on seismic earth pressures, as well as the attributes of geological layers and ground where foundations are established. Consequently, earthquake-resistant design has become imperative to ensure the safety of subterranean structures. The slurry wall method, due to its superior wall rigidity, excellent water resistance, and minimal noise and vibration, is often employed in constructing high-rise buildings in urban areas. However, given the separation between panels that constitute the wall, slurry walls possess limited resistance to seismic loads in the longitudinal direction. As a solution, several studies have probed into the possibility of interconnecting slurry wall panels to augment their seismic performance. In this research, we developed and evaluated a method for linking slurry wall panels using mechanical joints, including concrete-confined steel pipes and headed bars, through mock-up tests. We also assessed the constructability of the suggested method and compared it with other analogous methods. Any challenges identified during the mock-up test were discussed to guide future research in resolving them. The results of this study aid in enhancing the seismic performance of slurry walls through the development of an interconnected panel method. Further research can build on these findings to address the identified issues and improve the efficacy and reliability of the proposed method.

• Design Convergence Study
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• v.16 no.5
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• pp.1-20
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• 2017

Cardio-cerebrovascular disease is one of the chronic diseases that often attack people in Korea, and in fact, it ranks second in terms of death rate. This disease can be prevented by improving lifestyle, usual health care is important. But, in Korea most of the prevention or management programs adopt passive methods like using guide books or giving lectures, so it is not very effective in preventing the disease. Presently, the smart health care market is being developed in Korea and overseas. As an example, quantified self is being spread through wearable devices which are intended to measure each individual's health conditions and quantify body data into numbers for bettering habits. Accordingly, this author will explore and discuss wearable health care devices so as to prevent and manage cardio-cerebrovascular disease in a more active way. First, this study has classified wearable health care devices presently commercialized or related with cardio-cerebrovascular disease into wrist, clothes, or attaching types by the way of their attachment and analyzed them. After that, summing that up, this author performed cross-tabulations with other ways of preventing cardio-cerebrovascular disease. This will contribute to improving one's health care behavior about disease more actively and also work as an active interdisciplinary mechanism in research dealing with how to prevent disease afterwards.