• Journal of Dental Rehabilitation and Applied Science
• /
• v.26 no.4
• /
• pp.389-403
• /
• 2010

Titanium and gold-alloy abutments have been used for a long-time in the clinical situations, but the use of zirconia abutments also increased. This study was designed to compare and evaluate the microgap differences according to types of abutment and dynamic loading. Titanium abutment, zirconia abutment and gold-alloy abutment (UCLA plastic) were connected into titanium implants of external hexagonal structure US II ${\phi}$ $3.75{\times}11.5$ mm (Osstem Co., Seoul, Korea) with the tightening torque of 30 Ncm. A sine type dynamic loading of 25-250 N and $30^{\circ}$ inclination from long axis was applied for $10^5$ times. Using the SEM both before and after the loadings, implant-abutment interfaces were analyzed on the labial, palatal, mesial and distal surface. The microgaps before and after the loading were compared, no statistically significant difference was observed caused by the dynamic loading on the labial, palatal, mesial or distal surface. Statistically significant difference was observed between UCLA and titanium group and between UCLA and zirconia group on both before and after the loading(p<0.05). No statistically significant difference was found between titanium and zirconia group. Loadings for $10^5$ times did not show significant effect to the microgaps between implants and abutments.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.43 no.5 s.311
• /
• pp.1-9
• /
• 2006

Because most applications of vision-based object tracking demonstrate satisfactory operations only under very constrained environments that have simplifying assumptions or specific visual attributes, these approaches can't track target objects for the highly variable, unstructured, and dynamic environments like a traffic scene. An adaptive fusion framework is essential that takes advantage of the richness of visual information such as color, appearance shape and so on, especially at cluttered and dynamically changing scenes with partial occlusion[1]. This paper develops a particle filter based adaptive fusion framework and improves the robustness and adaptation of this framework by adding a new distinctive visual attribute, an image feature descriptor using SIFT (Scale Invariant Feature Transform)[2] and adding an automatic teaming scheme of the SIFT feature library according to viewpoint, illumination, and background change. The proposed algorithm is applied to track various traffic objects like vehicles, pedestrians, and bikes in a driver assistance system as an important component of the Intelligent Transportation System.

• Korean Journal of Cleft Lip And Palate
• /
• v.12 no.1
• /
• pp.33-40
• /
• 2009

구개열이 있으면 언어장애 음식섭취의 어려움, 구개범장근의 기능장애로 인한 이관의 개폐기능부전으로 중이의 액체고임, 부정교합등 여러 문제가 생길 수 있다. 따라서 구개성형술은 갈라진 경구개와 연구개를 막아주며 동적인 연구개를 만들어 주어 충분한 구개인두폐쇄를 하여 정상적 발음을 하는데 그 목표가 있다. 그 외에도 음식물을 정상적으로 섭취할 수 있고 중이염 및 난청을 일으킬 수 있는 기능을 개선시키고 정상적인 교합을 만들어주는데 있다. 위의 목표를 이루기 위해 지금까지 많은 수술 방법이 개발되었고 개선되어 왔다. 하지만 아직도 가장 효과적인 수술방법, 수술시기에 대하여 논쟁거리가 되고있다. 언어를 분명하게 하려면 연구개는 인두벽에 닿기 위해 후상방으로 올라가고 인두의 후벽과 측벽은 올라온 연구개에 닿으려고 수축함으로써 비인두와 구인두 사이의 공간이 좁아지게 됨으로써 가능하다. 따라서 발음이 정확하려면 비인두괄약(nasopharyngeal sphincter)을 합리적으로 만들어주어 비인두와 구인두를 분리해 주어야 한다. 비인두괄약을 조성해 주는 방법에는 구개범거근이 괄약기능을 할수 있도록 연구개내근성형술(intravelar veloplasty)을 시행하여 양편구개범거근을 횡위로 옮겨 연결하여 올림근 걸이(levator muscle sling)을 만드는 방법, 구개 연조직을 후방으로 밀어 구개 길이를 연장하는 방법, 인두 피판술을 하는 방법등이 있다. 구개범거근의 주행방향과 부착이 잘못되어 있는 것으로, 정상에서는 구개범거근이 횡으로 주행하여 연구개의 정중봉선(median raphe)에 부착하는 데 반해 구개열에서는 구개범거근이 전방으로 주행하여 개열 가까이에 있는 구개열 후연과 골선 개열연에 부착되어 있고 구개인두근과 구개수근이 연구개를 그냥 지나쳐직접 구개열 후연에 붙는다. 저자등은 완전 양측성 구개열을 연구개내근성형술 및 서골피판을 동반한 2개 점막성골막판을 이용한 구개성형술로 수술을 시행하여 다소의 지견을 얻었기에 문헌고찰과 함께 보고하는 바이다

• The korean journal of orthodontics
• /
• v.30 no.3 s.80
• /
• pp.273-285
• /
• 2000

The aim of this investigation was to evaluate the differences of two canti-leyer springs by using a new simulation system. This was done using a Calorific machine that compared iron uprighting spring and root uprighting spring. The Calorific machine was designed to allow observation of the whole process of tooth moving, and is composed of three parts(a temperature regulating system, electro-thermodynamic teeth, and an artificial alveolar bone component). The experiment of both mechanics were repeated five times and measured two times. The intra-examiner agreement and inlet-examiner agreement were $96.54\%\;and\;95.73\%$ and these data were statistically tested by paired t-test. The obtained results were as follows. 1. Distal and buccal movement of the anchor teeth were observed greater in the root uprighting spring than the crown uprighting spring. 2. Crown uprighting spring showed distal movement of the crown of lower second molar for 3.29mm but root uprighting spring showed only 1.68mm. 3. Crown uprighting spring exhibited forward movement of mesial and distal root of the lower second molar for 3.91mm, 3.60mm but the root uprighting spring showed 6.76mm, 6.26mm.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.480-493
• /
• 2007

Many railway-advanced countries are using the various types of track to reduce the track maintenance and repair cost according to the improvement of velocity. It spends on much maintenance and repair cost for ballast track due to abrasion of ballast, track irregularity and unisotropical ballast-support stiffness. The ballast track on railway bridge is accelerating the deterioration of ballast according to interaction of railway bridge and track. As continuing the deterioration, it is caused dynamic loads. Due to these effects, it increases negative loads of track and bridge. However, when designing the railway bridge, the effect of ballast track was applicate only dead load, so elastic behavior effect of ballast track is not influenced. Therefore, this paper presumes the stiffness of ballast track on railway bridge considering dynamic behavior of railway bridge, it was evaluated that effect on dynamic behaviors of railway bridge according to ballast track stiffness.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.34 no.3
• /
• pp.218-224
• /
• 2018

Macroglossia is an obstacle in regard to general prosthodontic restoration. Not only is it difficult to obtain support and stability from dentures manufactured from normal protocol, obtaining efficacy from basic mastication is also difficult. In such cases, realizing harmony between the occlusion and surrounding muscle structures may be important with regard to manufacture of stable full dentures, and it is necessary to form the appropriate polished surface for this case. The neutral zone is defined as the potential area resulting from the neuromuscular function that results in equilibrium between the outward force exerted by the tongue and the inward force exerted by the lips and cheeks. The artificial teeth of the full denture lies in this area, and if the polished zone follows the anatomic form of the dynamic muscles, the movement of the muscles simply acts as an element of stabilizing the dentures improving the esthetics through facial support.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.34 no.4
• /
• pp.324-330
• /
• 2018

In order to produce a stable denture for severe alveolar bone loss area, it is not only important that .0a suitable occlusion is established but also to consider compatibility with the surrounding muscle to form a suitable polished surfaces. Neutral zone is defined as a potential area where the neuromuscular system of the tongue, cheeks and lips is balanced can be determined through the neutral zone impression technique. And if artificial teeth are aligned within the neutral zone and the polished surface follows the anatomical form of the dynamic muscle, higher stability and retention of the denture may be obtained through coordination with the surrounding muscle tissue. This case is being reported since the concept of the neutral zone was applied to a patient with severely atrophic residual alveolar ridge and the result was clinically satisfactory in both function and aesthetics.

• The KIPS Transactions:PartB
• /
• v.13B no.5 s.108
• /
• pp.561-568
• /
• 2006

WPS(Wearable Personal Station) for next generation PC can define as a core terminal of 'Ubiquitous Computing' that include information processing and network function and overcome spatial limitation in acquisition of new information. As a way to acquire significant dynamic gesture data of user from haptic devices, traditional gesture recognizer based on desktop-PC using wire communication module has several restrictions such as conditionality on space, complexity between transmission mediums(cable elements), limitation of motion and incommodiousness on use. Accordingly, in this paper, in order to overcome these problems, we implement hand gesture recognition system using fuzzy algorithm and neural network for Post PC(the embedded-ubiquitous environment using blue-tooth module and WPS). Also, we propose most efficient and reasonable hand gesture recognition interface for Post PC through evaluation and analysis of performance about each gesture recognition system. The proposed gesture recognition system consists of three modules: 1) gesture input module that processes motion of dynamic hand to input data 2) Relational Database Management System(hereafter, RDBMS) module to segment significant gestures from input data and 3) 2 each different recognition modulo: fuzzy max-min and neural network recognition module to recognize significant gesture of continuous / dynamic gestures. Experimental result shows the average recognition rate of 98.8% in fuzzy min-nin module and 96.7% in neural network recognition module about significantly dynamic gestures.

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.4
• /
• pp.424-434
• /
• 2009

Statement of problem: Problems such as loosening and fractures of retained screws and fracture of implant fixture have been frequently reported in implant prosthesis. Purpose: Implant has weak mechanical properties against lateral loading compared to vertical occlusal loading, and therefore, stress analysis of implant fixture depending on its material and geometric features is needed. Material and methods: Total 28 of external hexed implants were divided into 7 of 4 groups; Group A (3i, FULL $OSSEOTITE^{(R)}$Implant), Group B (Nobelbiocare, $Br{\aa}nemark$ $System^{(R)}$Mk III Groovy RP), Group C (Neobiotec, $SinusQuick^{TM}$ EB), Group D (Osstem, US-II). The type III gold alloy prostheses were fabricated using adequate UCLA gold abutments. Fixture, abutment screw, and abutment were connected and cross-sectioned vertically. Hardness test was conducted using MXT-$\alpha$. For fatigue fracture test, with MTS 810, the specimens were loaded to the extent of 60-600 N until fracture occurred. The fracture pattern of abutment screw and fixture was observed under scanning electron microscope. A comparative study of stress distribution and fracture area of abutment screw and fixture was carried out through finite element analysis Results: 1. In Vicker's hardness test of abutment screw, the highest value was measured in group A and lowest value was measured in group D. 2. In all implant groups, implant fixture fractures occurred mainly at the 3-4th fixture thread valley where tensile stress was concentrated. When the fatigue life was compared, significant difference was found between the group A, B, C and D (P<.05). 3. The fracture patterns of group B and group D showed complex failure type, a fracture behavior including transverse and longitudinal failure patterns in both fixture and abutment screw. In Group A and C, however, the transverse failure of fixture was only observed. 4. The finite element analysis infers that a fatigue crack started at the fixture surface. Conclusion: The maximum tensile stress was found in the implant fixture at the level of cortical bone. The fatigue fracture occurred when the dead space of implant fixture coincides with jig surface where the maximum tensile stress was generated. To increase implant durability, prevention of surrounding bone resorption is important. However, if the bone resorption progresses to the level of dead space, the frequency of implant fracture would increase. Thus, proper management is needed.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.35 no.3
• /
• pp.160-169
• /
• 2019

Purpose: The purpose of this study was to evaluate the antimicrobial effects of a toothbrush with light-emitting diodes (LEDs) on periodontitis-associated dental biofilm attached to a zirconia surface by static and dynamic methods. Materials and Methods: Zirconia disks (12 mm diameter, 2.5 mm thickness) were inserted into a 24-well plate (static method) or inside a Center for Disease Control and Prevention (CDC) biofilm reactor (dynamic method) to form dental biofilms using Streptococcus gordonii and Fusobacterium nucleatum. The disks with biofilm were subdivided into five treatment groups-control, commercial photodynamic therapy (PDT), toothbrush alone (B), brush with LED (BL), and brush with LED+erythrosine (BLE). After treatment, the disks were agitated to detach the bacteria, and the resulting solutions were spread directly on selective agar. The number of viable bacteria and percentage of bacterial reduction were determined from colony counts. Scanning electron microscopy (SEM) was performed to visualize alterations in bacterial morphology. Results: No significant difference in biofilm formation was observed between dynamic and static methods. A significant difference was observed in the number of viable bacteria between the control and all experimental groups (P < 0.05). The percentage of bacterial reduction in the BLE group was significantly higher than in the other treated groups (P < 0.05). SEM revealed damaged bacterial cell walls in the PDT, BL, and BLE groups, but intact cell walls in the control and B groups. Conclusion: The findings suggest that an LED toothbrush with erythrosine is more effective than other treatments in reducing the viability of periodontitis-associated bacteria attached to zirconia in vitro.