• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.515-516
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• 2006

The goal of total disc replacement is to restore pain-free mobility to a diseased functional spinal unit, by replacing the degenerated disc with a mobile bearing prosthesis. SB Charite III is named commercial product as the Artificial Intervertebral Disc (AID). SB Charite III consists of sliding core and endplate made by Ultra-high Molecular Weight Polyethylene (UHMWPE) and cobalt chrome alloy, respectively. To evaluate the effect of von-Mises stress in AID, and three-dimensional finite element model of AID analysis was preformed for four different loading types of sliding core. Consequently, endplate was compared with a compressive preload at 400N and flexion moment at $3{\sim}9Nm4. Therefore, this research has obtained result that von-Mises stress of sliding core in AID disc by radius curvature.

• Journal of Korean Dental Science
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• 제10권2호
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• pp.74-81
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• 2017

This report describes two cases of complete arch implant-supported restorations. The first patient had seven dental implants in each arch with monolithic zirconia frameworks. At four weeks' follow-up, the one-piece maxillary framework was fractured, which was re-designed and re-fabricated using laser-sintered cobalt-chrome alloy. The second patient had four implants in the mandible only. A mandibular monolithic zirconia framework and a maxillary conventional complete denture were fabricated and delivered. At five years' follow-up, the patient reported no significant discomfort. Careful consideration and monitoring of the status of antagonistic arches and stress distribution on zirconia frameworks were suggested for complete arch implant-supported fixed restorations.

• 센서학회지
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• 제15권3호
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• pp.199-204
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• 2006

Carbon nanotube (CNT) mats grown by thermal chemical vapor deposition on a micromachined substrate with a chrome heater and a diaphragm were investigated as sensing materials of resistive gas sensors for nitrogen dioxide ($NO_{2}$) gas. The aligned CNT mats fabricated into mesh and serpentine shapes by the patterned cobalt catalyst layer. CNT mats showed a p-type electrical resistivity with decreasing electrical resistance upon exposure to $NO_{2}$. All sensors exhibited a reversible response at a thermal treatment temperature of $130^{\circ}C$ for about 5 minutes. The resistance change to $NO_{2}$ of the mesh-shaped CNT mats was larger than that of the serpentine-shaped CNT mats.

• 한국염색가공학회지
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• 제8권6호
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• pp.40-46
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• 1996

In order to investigate a practical application of fibrous absorbents to transition metals such as copper, nickel, cobalt, chrome, and iron, amidoximated fiber as a particular class of solid chelate agents were prepared from acrylic fibers treatment with hydroxylamine. The adsorption mechanisms of metal ions onto amidoximated acrylic fibers and their complexes were studied. Amidoximation of acrylic fiber with hydroxylamine is found to be first-order reaction, followed by the disappearance of infrared adsorption peaks due to nitrile groups of acrylic fibers. The uptake of metal ions onto amidoximated acrylic fiber is increased with temperature raising and the adsorption is also depended on pH of the soiutions. About 70% of metal ions can be recovered from aqueous solutions of Ni(II), Co(II), Cr(III), and Fe(II) on the concentration below 5x 10$^$^{-4}$ in the range of pH 2.1~10.0. Transition metals are adsorbed to form complex with amidoxime group by the ligand sites such as C=N, NH, NO, NHOH.OH.

• The Journal of Advanced Prosthodontics
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• 제9권1호
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• pp.52-56
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• 2017

PURPOSE. Considering the importance of metal-ceramic bond, the present study aimed to compare the bond strength of ceramics to cobalt-chrome (Co-Cr) alloys made by casting and selective laser melting (SLM). MATERIALS AND METHODS. In this in-vitro experimental study, two sample groups were prepared, with one group comprising of 10 Co-Cr metal frameworks fabricated by SLM method and the other of 10 Co-Cr metal frameworks fabricated by lost wax cast method with the dimensions of $0.5{\times}3{\times}25\;mm$ (following ISO standard 9693). Porcelain with the thickness of 1.1 mm was applied on a $3{\times}8-mm$ central rectangular area of each sample. Afterwards, bond strengths of the samples were assessed with a Universal Testing Machine. Statistical analysis was performed with Kolmogorov-Smirnov test and T-test. RESULTS. Bond strength in the conventionally cast group equaled $74.94{\times}16.06\;MPa$, while in SLM group, it equaled $69.02{\times}5.77\;MPa$. The difference was not statistically significant ($P{\leq}.05$). CONCLUSION. The results indicated that the bond strengths between ceramic and Co-Cr alloys made by casting and SLM methods were not statistically different.

• Restorative Dentistry and Endodontics
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• 제14권1호
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• pp.121-133
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• 1989

In order to compare the accessory canal filling effects of the three root canal filling methods with gutta-percha, the author fabricated artificial root canal mold with the first and second accessory canals of chrome-cobalt alloy. After the artificial root canal was filled with gutta-percha by lateral condensation, vertical condensation and low-temperature thermoplasticized gutta-percha injection-molded method, twenty five times respectively, the gutta-percha forced into the first and second accessory canals were measured with caliper for length. The results were as follows: 1. The filling in both accessory canals was most effective in low-temperature thermoplasticized gutta-percha injection-melded method followed in such order as: vertical condensation method and lateral condensation method (p < 0.01). 2. The filling effect of the second accessory canal was more or less higher than that of the first one (p < 0.05). 3. Low-temperature thermoplasticized gutta-percha injection-molded method was fastest in time needed for root canal filling followed by lateral condensation method and vertical condensation method.

• Journal of Oral Medicine and Pain
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• 제25권2호
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• pp.167-172
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• 2000

Both immune reaction and hypersensitivity reaction are occurred by the same mechanism, the antigen and antibody reaction. The favorable result of this reaction towards a host is called clinically an immune reaction and the opposite results is called an hypersensitivity reaction. Type IV hypersensitivity reaction is a delayed type which is related to the cellular immune reaction and a contact hypersensitivity is included in this type. Various dental materials such as metal (mercury, nickel, chrome, cobalt), resin and eugenol are etiologic substances. Patch test kit is composed of test substance with a controlled concentration which respond only to a susceptible patient and an aluminum chamber, and etiologic substances for hypersensitivity can be easily and comfortably found just by applying the kit to the patient's skin. In this case report, the patch test was performed to a patients with oral lichen planus and the allergen, restorative material was found. After removal of the matching restoration from the patient's mouth, the symptom was improved.

• 대한치과기공학회지
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• 제43권3호
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• pp.93-98
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• 2021

Purpose: The aim of this study was to observe the surface roughness and surface topography of cobalt-chrome (Co-Cr) alloys with grinding time in dental barrel finishing. Methods: This study involved two types of Co-Cr alloys. Specimens were manufactured with the dimensions 10×10×2 mm. Each specimen was cast according to the manufacturer's instructions. The cast alloys were polished for 35 minutes at intervals of five minutes in an automatic barrel finishing. Specimens were imaged with a three-dimensional optical microscope to measure surface roughness. Results: BC specimens and GM specimens had the highest roughness (Ra) values in the ungrained control group, and the lowest Ra values were measured 20 minutes after grinding. Conclusion: The best conditions for grinding Co-Cr alloy using a dental barrel finishing were a weight ratio of polishing media, water, and compound of 150 g:200 g:5 g, and a rotation speed of 450 rpm. Grinding time to obtain appropriate surface roughness should be limited to 15 to 30 minutes.

• 대한치과보철학회지
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• 제61권4호
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• pp.284-292
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• 2023

안정적인 구치부 교합지지는 적절한 저작기능과 정상적인 안모의 유지를 위해 매우 중요하다. 특히 65세 이상의 고령환자에서는 저작기능이 충분한 영양섭취와 환자의 전신건강에 직접적인 영향을 미친다. 본 증례에서는 상악 무치악, 하악 양측 구치부 치아 상실을 보이는 고령환자의 구치부 교합지지를 회복해주기 위해 상악 총의치를 제작하여 이상적인 교합평면을 설정하였고, 하악 양측 구치부에 컴퓨터 가이드 임플란트 식립 수술을 진행하였다. 임플란트 지지 임시 수복물을 이용한 임플란트 즉시부하를 통해 환자가 수술 후에도 음식 섭취를 원활하게 할 수 있도록 하였다. 하악 구치부 지르코니아 고정성 보철수복을 완료한 후, 상악 총의치 인공치의 교합면을 Cobalt-Chrome계 금속 합금으로 치환하여 마모 저항성을 향상시켰다. 상악 가철성 총의치, 하악 양측 구치부 고정성 보철 치료를 통해 환자의 교합지지와 저작기능을 빠르게 회복해주고, 최종 치료단계에서는 마모에 대한 장기적 안정성도 얻을 수 있었기에 이를 보고하고자 한다.

• 한국환경보건학회지
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• 제32권2호
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• pp.186-191
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• 2006

Metal contamination of medicinal herbs is of growing concern because of their potential adverse health effects. In this study, metal exposures were estimated and their potential health risks were preliminarily evaluated using available data including metal contamination levels and consumption estimates of herbal medicine in Korea. Consumption and contamination data of 34 medicinal herbs abundantly used in Oriental medicine in Korea were used in this study. Lead, mercury, arsenic, cadmium, cobalt, and chrome were identified as contaminants of potential health concerns. Even based on a conservative exposure scenario, i.e., consuming 5 times more herbal medicine with 95th percentile contamination levels, health risks associated with herbal medicine consumption were estimated to be minuscule. Herbal consumption was 0.3% of the provisional tolerable daily intake levels recommended by Joint Expert Committee on Food Additives (JECFA) of WHO/FAO. However, it should be noted that there are several important assumptions and uncertainties associated with this evaluation: This study was conducted for only 34 types of medicinal herbs of which consumption and metal contamination data were available. In addition, there are no reliable herbal medicine consumption data among Korean population. The pattern and amount of herbal (medicine) consumption in Korea need to be investigated in order to conduct more refined risk assessment associated with metal contamination in medicinal herbs.