• 구강회복응용과학지
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• 제39권3호
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• pp.158-167
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• 2023

최근 치의학 분야에서 디지털 기술이 발달함에 따라 computer-aided design-computer-aided manufacturing (CAD/CAM)을 이용한 의치 제작 진료 단계의 변화를 가져왔다. CAD/CAM 기술을 이용한 의치 제작 방식은 제작기간과 내원 간격의 단축으로 임상적인 효율성과 편리함을 제공함과 동시에 기공을 단순화하여 오류 발생을 감소시켰다. 본 증례는 복잡한 병력과 신체적 장애를 가진 환자에게 기존의 임시의치를 디지털 방식으로 복제 및 출력하여 개인 트레이로 활용하였고, 부가중합형 실리콘 인상재로 채득한 최종 인상체에는 수직고경과 중심위, 상악 전치부의 각도 및 길이에 대한 정보가 포함되어 있으며 이를 통해 제작 기간과 내원 간격을 단축하여 환자의 만족도를 높일 수 있었다. 최종 의치는 밀링 방식 및 monolithic disc를 이용하여 제작하였고, 적절한 안정과 유지, 지지를 보여 기능적, 심미적으로 만족스러운 결과를 얻을 수 있었다.

• 대한기계학회논문집A
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• 제32권11호
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• pp.924-929
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• 2008

The rate of wear of cam followers in a valve train system is mainly a function of contact stress between the cam and the follower, sliding velocity and hydrodynamic film thickness between the two mating surfaces. The wear or surface fatigue can be reduced by maximizing the elastohydrodynamic film thickness. In this paper, an attempt has been made to estimate the optimal specific film thickness of cam-follower system quantitatively. A general TES polynomial function with real values of exponents is developed and genetic algorithm (GA) is used as optimization techniques for maximizing the minimum specific film thickness. The optimization programs enumerate values of the exponents for synthesis of cam displacement curves. The results show that the minimum film thickness can be increased considerably, e.g. approximately 7% in this paper.

• Journal of Biosystems Engineering
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• 제16권3호
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• pp.228-238
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• 1991

Cam plays very important roles due to continuous requirement for the high-speed and automation of the machinery. A large number of studies of cam curve were carried out by many researchers, and CNC milling and machining center for manufacturing cam have been widely used recently. The purpose of this study was to develop a CAD/CAM system for cam using QuickBasic language in 16-bit PC for application of cam design and manufacturing. Results obtained were as follows : 1. It was possible to input data by entering cam angle and its corresponding R, from 0 to 360 deg. of cam angle. The tediousness at entering data was minimized because of the same data format for both cylindrical cam and disc cam, and free format used for data file. 2. It was possible to design cam by choosing only the number of cam curve because of developing the CAD/CAM program with dimensionless method of cam curves including widely used 19 kinds. After selecting the number of the cam curve, the CAD/CAM system automatically shows the characteristics of cam motion enough to help a designer to decide : displacement, velocity, acceleration and jerk. 3. It was possible to execute, in an efficient way, both the cam profile synthesis and the generation of NC program for CNC machining center by using the input data. 4. This NC program generated by the CAD/CAM system developed here, was evaluated as positive in relation with actual manufacturing experiments and thought to be useful in its application without any modification. It can be said that this CAD/CAM system could be used by the beginners to design and manufacture the cam automatically as the system consists of very simple dialogue methods. In addition, self-developed QuickBasic would be would used as a basic tool for further stuides in this area of research, together with application.

• 구강회복응용과학지
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• 제38권4호
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• pp.242-248
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• 2022

최근 CAD/CAM 기술의 발달을 통해 의치 제작에도 활용되고 있다. 디지털 방식으로 의치를 제작했을 때 전통적인 방법과 비교하여 제작 과정을 용이하게 하고 내원 횟수 감소, 오차 감소 등의 이점을 갖는다. 본 증례는 오래된 의치의 사용으로 인해 수직 고경 회복이 필요한 환자에서 CAD 프로그램을 이용하여 수직 고경을 증가시켰으며 최종 의치는 밀링방식을 통해 monolithic disc를 이용하여 제작한 증례이다. 기존 의치를 이용하여 중심위를 인기하였으며 구내 스캔과 기존 의치 모델 스캔을 정보를 이용하여 시적용 의치를 제작하고 환자에게 장착해 정중선, 교합관계 등을 평가하였다. 시적용 의치 평가를 기반으로 밀링방식 및 monolithic disc를 이용하여 최종 의치를 제작하였고 최종 의치는 기능적 및 심미적으로 만족스러운 결과를 보였다.

• 대한치과보철학회지
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• 제61권4호
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• pp.268-274
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• 2023

본 증례는 요양병원에 입원치료 중인 환자에서 치과에 내원하기 힘든 점과 의치 분실이 많은 점을 고려하여 내원 횟수를 감소시키고 재제작이 쉬운 CAD-CAM 총의치를 제작하였다. 환자가 적응한 기존 임시의치의 형태 및 수직고경, 악간관계를 최종의치 제작에 반영하기 위해 기존 임시의치를 스캔하고 프린팅한 개인트레이로 폐구인상을 채득하였다. UTS CAD를 이용하여 디지털 안궁이전하고 CAD 소프트웨어에서 치아배열 후 상하악 총의치를 단일 구조의 디스크로 의치상과 인공치를 한번에 절삭하여 제작하였다.

• The Journal of Advanced Prosthodontics
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• 제16권2호
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• pp.115-125
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• 2024

PURPOSE. The purpose of this in vitro study was to investigate the fracture resistance, surface hardness, and color stain of 3D printed, CAD-CAM milled, and conventional interim materials. MATERIALS AND METHODS. A total of 80 specimens were fabricated from auto polymerizing polymethyl methacrylate (PMMA), bis-acryl composite resin, CAD-CAM polymethyl methacrylate resin (milled), and 3D printed composite resin (printed) (n = 20). Forty of them were crown-shaped, on which fracture strength test was performed (n = 10). The others were disc-shaped specimens (10 mm × 2 mm) and divided into two groups for surface hardness and color stainability tests before and after thermal cycling in coffee solution (n = 10). Color parameters were measured with a spectrophotometer before and after each storage period, and color differences (CIEDE2000 [DE00]) were calculated. The distribution of variables was measured with the Kolmogorov Smirnov test, and one-way analysis of variance (ANOVA), Tukey HSD, Kruskal-Wallis, Mann-Whitney U tests were used in the analysis of quantitative independent data. Paired sample t-test was used in the analysis of dependent quantitative data (P < .05). RESULTS. The highest crown fracture resistance values were determined for the 3D printed composite resin (P < .05), and the lowest were observed in the bis-acryl composite resin (P < .05). Before and after thermal cycling, increase in mean hardness values were observed only in 3D printed composite resin (P < .05) and the highest ΔE₀₀ value were observed in PMMA resin for all materials (P < .05). CONCLUSION. 3D printing and CAD-CAM milled interim materials showed better fracture strength. After the coffee thermal cycle, the highest surface hardness value was again found in 3D printing and CAD-CAM milled interim samples and the color change of the bis-acryl resin-based samples and the additive production technique was higher than the PMMA resin and CAD-CAM milled resin samples.

• 대한치과보철학회지
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• 제52권2호
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• pp.67-73
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• 2014

연구 목적: 본 연구의 목적은 주조, 3-D printing laser sintered 및CAD/CAM technology를 이용한 milling 방법으로 제작된 치과용 코발트-크롬 합금의 기계적 물성을 비교하고 파절 단면의 미세 구조를 살펴보는 데 있다. 이를 통해 새롭게 소개된 제작 기법 - 3D-printing laser sintered - 이 치과용 합금 제작으로 적합한 지 알아보고자 한다. 연구 재료 및 방법: 36개의 flat disc 모양의 시편을 제작하여 제작 방법에 따라 세 집단으로 나누었다; 주조 방식으로 제작한 12개, laser sintering 방법으로 12개, CAD/CAM milling 방법으로 12개의 시편을 제작하여 표면 경도 시험을 시행하였다. 또한 각 집단 별로 12개의 dumbbell 모양의 시편을 제작하여 인장 강도 시험을 시행하였다. 통계량이 비모 수적 통계 분포를 보였으므로 Kruskal-Wallis 검정을 이용하여 각 실험군의 인장 강도 시험 결과를 비교했으며, 통계적 유의 수준은P=.05로 설정하여 Mann-Whitney 및 Bonferroni 사후 검정을 시행하였다. 전자 주사 현미경을 사용하여 파절 단면의 미세 구조를 관찰하였다. 결과: Vickers hardness test에서 세 집단간에 모두 유의한 차이가 있었고, 주조 방식으로 제작된 실험군에서 가장 큰 표면 경도(455.88 Hv)가, CAD/CAM milling으로 제작된 실험군에서 가장 낮은 표면 경도(243.40 Hv)를 나타냈다. 최대 인장 강도, 0.2% 항복강도, elongation 및 elastic modulus에서 세 집단간에 모두 유의한 차이가 나타났으며, CAD/CAM milling으로 제작한 실험군에서 가장 높은 최대 인장 강도(1442.94 MPa)가, laser sintered 실험군에서 가장 큰 0.2% 항복 강도(1136.15 MPa)가 나타났다. 파절 단면의 전자 주사 현미경 관찰 결과, 주조 시편에서는 독특한 성긴 모양과 전형적인 주조 다공성 구조가 관찰되었고, laser sintered 시편에서는 편평한 면을 동반한 거친 결정 구조가, 그리고 milled 시편에서는 균일하고 규칙적인 치밀 미세 구조가 나타났다. 결론: 서로 다른 제작 방법은 코발트-크롬 합금의 물리적 성질과 파절 단면의 미세 구조에 영향을 미쳤다. 주조 방식으로 제작된 시편에서 가장 큰 표면 경도가, milling으로 제작된 시편에서 가장 큰 인장 강도를 나타냈으며, 본 연구의 모든 실험군에서 치과용 합금의 ISO 기준에 부합하는 물성을 보였다.

• 셀메드
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• 제4권1호
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• pp.4.1-4.4
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• 2014

Gynura segetum, family Asteraceae is a cultivated species and can be found growing in the tropical regions of Indonesia and Malaysia. The plant is known for its use for the treatment of cancer, inflammation, diabetes, hypertension and skin afflictions. In the current study, anti-inflammatory effect of Gynura segetum leaf has been investigated. The present study investigated the in vivo anti-inflammatory effect of Gynura segetum leaf by using hen's egg test-chorioallantoic membrane (HET-CAM) assay. Different solvent extract of Gynura segetum leaf were tested, the most active methanol extract was further fractionated and tested. Among the extracts tested, the methanol extract showed a significant good anti-inflammatory effect (76.8% inhibition at 50 ${\mu}g/disc$) on the HET-CAM assay as compared with the anti-inflammatory drug indomethacin (82.1% inhibition). However, the fractionated sample exhibited a significantly lower activity in comparison to crude methanol extract. The results demonstrated that Gynura segetum leaf displayed remarkable anti-inflammatory effects, which support the folkloric uses of this plant for treatment of inflammation.

• Restorative Dentistry and Endodontics
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• 제38권3호
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• pp.134-140
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• 2013

Objectives: There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent) and Rosetta SM (Hass), and to observe their crystalline structures. Materials and Methods: Biaxial flexural strength was tested according to ISO 6872 with 20 disc form specimens sliced from each block before and after heat treatment. Also, the crystalline structures were observed using field-emission scanning microscopy (FE-SEM, Hitachi) and x-ray diffraction (XRD, Rigaku) analysis. The mean values of the biaxial flexural strength were analyzed by the Mann-Whitney U test at a significance level of p = 0.05. Results: There were no statistically significant differences in flexural strength between IPS e.max CAD and Rosetta SM either before heat treatment or after heat treatment. For both ceramics, the initial flexural strength greatly increased after heat treatment, with significant differences (p < 0.05). The FE-SEM images presented similar patterns of crystalline structure in the two ceramics. In the XRD analysis, they also had similar patterns, presenting high peak positions corresponding to the standard lithium metasilicate and lithium disilicate at each stage of heat treatment. Conclusions: IPS e.max CAD and Rosetta SM showed no significant differences in flexural strength. They had a similar crystalline pattern and molecular composition.

• The Journal of Advanced Prosthodontics
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• 제11권2호
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• pp.128-137
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• 2019

PURPOSE. The aim of this study was to compare the effect of different finishing and polishing techniques on water absorption, water solubility, and microhardness of ceramic or glass-polymer based computer-aided design and computer-aided manufacturing (CAD/CAM) materials following thermocycling. MATERIALS AND METHODS. 150 disc-shaped specimens were prepared from three different hybrid materials and divided into five subgroups according to the applied surface polishing techniques. All specimens were subjected up to #4000 grit SiC paper grinding. No additional polishing has been done to the control group (Group I). Other polishing procedures were as follows: Group II: two-stage diamond impregnated polishing discs; Group III: yellow colored rubber based silicone discs; Group IV: diamond polishing paste; and Group V: Aluminum oxide polishing discs. Subsequently, 5000-cycles of thermocycling were applied. The analyses were conducted after 24 hours, 7 days, and 30 days of water immersion. Water absorption and water solubility results were analyzed by two-way ANOVA and Tukey post-hoc tests. Besides, microhardness data were compared by Kruskal-Wallis and MannWhitney U tests (P<.05). RESULTS. Surface polishing procedures had significant effects on water absorption and solubility and surface microhardness of resin ceramics (P<.05). Group IV exhibited the lowest water absorption and the highest microhardness values (P<.05). Immersion periods had no effect on the microhardness of hybrid ceramic materials (P>.05). CONCLUSION. Surface finishing and polishing procedures might negatively affect physical properties of hybrid ceramic materials. Nevertheless, immersion periods do not affect the microhardness of the materials. Final polishing by using diamond polishing paste can be recommended for all CAD/CAM materials.