• 대한치과보철학회지
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• 제37권4호
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• pp.531-541
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• 1999

The purpose of this study was to compare surface roughness and bone formation around two types of threaded commercially pure titanium implants manufactured by two different companies. The test implants were manufactured by Sumin synthesis dental materials Co. (Avana, Busan, Korea), while the controls were manufactured by Nobel Biocare (MK II, Goteborg, Sweden). To compare bone formation adjacent to newly product implant with $Br{\aa}nemark$ MK II implant, surface roughness was measured by Accurate 1500M and histomorphometric analysis was done. The results were as follows: 1. Measurement of surface roughness showed that Avana implant had a slightly more irregular surface compared with $Br{\aa}nemark$ implant. 2. In the light microscopic studies, no infiltration of inflammatory cells nor the giant cells were observed on both groups. 3. In the light and fluorescent microscopic studies, the amount of osseointegration and the extent and the timing of bone formation were similar. 4. There were no statistically difference between two groups in the average bone to implant con-tacts. Branemark implant; 67% (SD 23%), Avana implant; 70% (SD 16%). Comparing with $Br{\aa}nemark$ implant, Avana implant made of CP grade II titanium showed similar good bone healing, formation and osseointegration.

• 소성∙가공
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• 제29권3호
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• pp.144-150
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• 2020

In this paper, we propose the generation of a double enveloping worm thread profile with a non-developable ruled surface. Thread surface machining cuts all the way from the tip to the tooth root at one time, like full-face contact machining, rather than cutting several times like point machining. This cutting can reduce the cutting duration and achieve the smooth surface that does not require a grinding process for the threaded surface. The mathematical model of the cutting process was developed from theoretical equations, and the tooth surface was generated using two parameters and modeled in the CATIA using the generated Excel data. Additionally, the machining process of the worm was simulated in a numerical control simulation system. To verify the validity of the proposed method, the deviation between the modeling and the workpiece was measured using a 3D measuring machine.

• 한국압력기기공학회 논문집
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• 제16권1호
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• pp.84-91
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• 2020

The APR1400 reactor stud holes can be stuck due to high temperatures, high pressure, prolonged engagement, and load changes according to pressure changes in the reactor. Threaded surfaces of a stud hole should be cleaned for the sealing of pressure in reactor vessel by removing any foreign materials which may exist in the stud holes. Human workers can access to the stud hole for the cleaning of stud holes manually, but the radiation exposure of human workers is increased. Robot is an effective way to work in hazardous area. So we introduced robot for the cleaning of stud holes. Localization of mobile robots is generally based on odometry, but with increased mileage, position errors can be accumulated. In order to eliminate cumulative error and to ensure stability of its driving, laser sensors and new control algorithm were utilized. The distance between the robot and the wall was measured by laser sensors, and the control algorithm was implemented so as to travel the desired trajectory by using the measured values from sensors. The performance of driving and hole sensing were verified through field application, and mobile robot was confirmed to be applicable to the APR 1400 NPP.

• 대한치과보철학회지
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• 제41권3호
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• pp.271-287
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• 2003

Statement of problem: Resonance frequency analysis (RFA) has been increasingly served as a non-invasive and objective method for clinical monitoring of implant stability. Many clinical studies must be required for standardized baseline data using RFA. Purpose: This study was performed to evaluate RFA value changes in two stage surgery group and one stage surgery group in patients. Material and method: Forty-seven mandibles in consecutively implant installed patients were selected for this study and 141 fixtures were installed. Ninety-three fixtures were double threaded, machined surface design ($Br{\aa}anemark^{(R)}$ MK III, Nobel Biocare AB, Goteborg, Sweden) and 48 fixtures were root form, threaded, HA-coated surface one ($Replace^{TM}$, Steri-Oss/Nobel Biocare AB, USA). Among those, each 10 fixture was installed in one stage group patients. ISQ values were measured using $Osstell^{TM}$ (Integration Diagnostics Ltd. Sweden) during fixture installation, at healing abutment connection and in the loading period for two stage surgery group patients and during at each 4, 6, 8, 10, 12week and in the loading phase for one stage surgery group patients and evaluated the changes according to the time and fixture type. Results: In two stage surgery group, mean and SO of ISQ values of machined surface implants were $76.85{\pm}3.74,\;75.76{\pm}5.04,\;75.73{\pm}4.41$ and those of HA-coated surface implant were $75.05{\pm}6.23,\;77.58{\pm}5.23,\;78.32{\pm}4.29$ during fixtures installation, at healing abutment connection and in the loading period, respectively. In one-stage surgery group, the ISQ values of machined surface and HA-coated surface implants decreased until 4 or 6 week and maintained at plateau for 1-3 week and increased to the loading period. Conclusions: Machined and HA-coated surface implants showed minimal ISQ changes with time if they were installed at the sites showing at least intact cortical plate and good bone qualities. And HA-coated implants had a tendency to show somewhat increased ISQ values with time.

• 대한설비공학회지:설비저널
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• 제17권3호
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• pp.230-237
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• 1988

An experiment was carried out to study the condensation heat transfer enhancement of horizontal circular cylinders with varying outside surface configurations. The refrigerant used is Freon-22 and the test condensing temperature is 34.1C. Pin-finned tube shows about 2.5-3.5 times higher overall heat transfer coefficient compared to that of smooth surface tube, thus has larger encomic benifit for condenser design. The condensation heat transfer coefficient was shown to increase as the fin-pitch of the pin-finned tube decreases for film Reynolds number larger than 100.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제10권6호
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• pp.499-506
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• 2004

제안된 동판 표면 검사 시스템은 PC-기반으로 다중 스레드 기법과 다중 CPU를 이용해 동판 표면의 결함을 실시간으로 검사하는 시스템이다. 초고속 라인 스캔 카메라로 영상 취득 보드에 영상을 실시간으로 취득하여 처리할 때, 더블 버퍼링 방법으로 입출력과 처리가 동시에 수행되어 처리 속도를 높인다. 다중 스레드 기법에서는 시스템 자원 활용과 다중 스레드로 CPU의 사용을 최대화하여 실시간 처리하며, 다중 스레드 구조로도 실시간 처리가 어려운 경우에는 다중 CPU를 사용하여 이를 해결한다. 또한 동판 표면 영상에서 결함 검출하여 분류할 때, 실시간 처리를 만족시키기 위해서 결함영상의 공분산 행렬의 고유치 비율, 명암차 등의 연산으로 분류할 수 있는 방법을 제시한다. 결함의 검출은 조명 불균형에 대한 보상 처리가 적용된 다음 임계치에 의해 검출된다. 검출된 결함은 제안된 분류 방법으로 특징을 분석한 뒤 결함의 형태를 분류한다. 특징은 결함 너비와 고유치 비율, 명암차 등이 사용되었다. 제시된 방법을 검증하기 위해서 총 141개의 결함을 분류하는 실험이 진행되었고, 결과로는 89.4% 성공률을 보였다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권4호
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• pp.293-300
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• 2001

A polyrotaxane-biotin conjugate was synthesized and its interaction with streptavidin measured using surface plasmon resonance(SPR) detection. A biodegradable polyrotaxane in which ca, 22 molecules of ${\alpha}$-cyclodextrina(${\alpha}$-CDs) were threaded onto a poly(ethylene oxide) chain(M$\sub$n:4,000) capped with benzyloxycarbonyl-L-phenylalanine was conjugated with a biotin hydorazide and 2-aminoethanol after activing the hydroxyl groups of ${\alpha}$-CDs in the polyrotaxane using N, N'-carbonyldiimidazole. The results of the high-resolution $^1$H-nyclear lmagnetic resonance($^1$H-NMR)spectra and gel permeation chromatography of the conjugate showed that ca, 11 biotin molecules were actually introduced to the polyrotaxane scaffold. An SPR analysis showed that the binding curves of the biotin molecules in the conjugate on the streptavidin-deposited surface changed in a concentration dependent manner, indicating that the biotin in the conjugate was ac-tually recognized by streptavidin. The association equilibrium constant(K$\sub$a/) of the interaction be-tween the conjugate and steptavidin tetramer was of the order 10$\^$7/. These results suggest that polyrotaxane is useful for scaffolds as a polymeric ligand in biomedical fields.

• 대한치과보철학회지
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• 제46권6호
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• pp.602-609
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• 2008

STATEMENT OF PROBLEM: Loss of the marginal bone to the first thread have been accepted but continuous effort have been made to reduce this bone loss by varying implant design and surface texture. PURPOSE: This animal study has examined the histomorphometric variations between implants with micro-thread, micro-grooved and turned surfaced neck designs. MATERIAL AND METHODS: Four mongrel dogs have been used the premolars removed and left to heal for three months. One of each implant systems with turned neck, micro-thread and micro-grooved were placed according to the manufacturers’protocol and left submerged for 8 and 12 weeks. These were then harvested for histological examination. RESULTS: The histologically all samples were successfully ossointegrated and active bone remodelling adjacent to implants. With the micro-grooved implants 0.40 mm and 0.26 mm of the marginal bone level changes were observed at 8 and 12 weeks respectively. The micro-threaded implants had changes of 0.79 mm and 0.56 mm at 8 and 12 weeks respectably. The turned neck designed implants had marginal bone level changes of 1.61 mm and 1.63 mm in 8 and 12 weeks specimens. A complex soft tissue arrangement could be observed against micro-threaded and micro-grooved implant surfaces. CONCLUSION: Within the limitations of this study, it could be concluded that implants with micro-grooved had the least and the turned neck designed implants had the most changes in the marginal bone level. The textured implant surfaces affect soft tissue responses.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제30권5호
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• pp.417-427
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• 2008

The aim of this study is to investigate the effect of anodizing surface to osseointegration of implant by using of resonance frequency analysis (RFA), quantitative and qualitative assessment of an anodically modified implant type with regard to osseous healing qualities. A total of 96 screw-shaped implants were prepared for this study. 72 implants were prepared by electrochemical oxidation with different ways. 24 (group 1 SP) were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid. 24 (group 2GC) were prepared at galvanostatic mode in calcium glycerophosphate and calcium acetate and 24 (group 3 CMP (Calcium Metaphosphate) Coating were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid followed by CMP coating. Rest of 24 (control group were as a control group of RBM surface. Bone tissue responses were evaluated by resonance frequency analysis (RFA) that were undertaken at 2, 4 and 6 weeks after implant placement in the mandible of mini-pig. Group 1 SP (anodized with sulfuric acid and phosphoric acid implants) demonstrated slightly stronger bone responses than control Group RBM. Group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) demonstrated no difference which were compared with control group. Group 3 GMP (anodized and CMP coated implants) demonstrated slightly stronger and faster bone responses than any other implants. But, all observation result of RF A showed no significant differences between experimental groups with various surface type. Histomorphometric evaluation demonstrated significantly higher bone-to-implant contact for group 2 GC. Significantly more bone formation was found inside threaded area for group 2 GC. It was concluded that group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) showed more effects on the bone tissue responses than RBM surface in initial period of implantation. In addition, CMP showed a tendency to promote bone tissue responses.

• Macromolecular Research
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• 제14권1호
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• pp.73-80
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• 2006

Sulfonated poly(ethylene glycol) (PEG-$SO_{3}$) grafted polyrotaxanes (PRx-PEG-$SO_{3}$) were prepared in order to utilize the unique properties of PEG-$SO_{3}$ and the supramolecular structure of PRx, in which PEG-$SO_{3}$ grafted $\alpha$-cyclodextrins ($\alpha$-CDs) were threaded onto PEG segments in a PEG-b-poly(propylene glycol) (PPG)-b-PEG triblock copolymer (Pluronic) chain capped with bulky end groups. Some of the PRx-PEG-$SO_{3}$ demonstrated a higher anticoagulant activity in case of PRx-PEG-$SO_{3}$ (P 105), and compared with the control they showed a lower fibrinogen adsorption in PRx-PEG-$SO_{3}$ (F68) and a higher binding affinity with fibroblast growth factor. The obtained results suggested that polyrotaxane incorporated with PEG-$SO_{3}$ may be applicable to the surface modification of clinically used polymers, especially for blood/cell compatible medical devices.