• 대한치과보철학회지
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• 제30권2호
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• pp.155-166
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• 1992

In dentistry, precious metal alloys are, mainly due to economic factors, increasingly displaced by alternatives containing Ni-Cr-Co. There are some reports where hypersensitive reactions to Ni-Cr-Co alloys are presented and discussed. The reactions reported vary from mucosa contact stomatitis to generalized dermatitis without any oral mucosal reaction. The purpose of this study was to investigate the incidence of nickel, chrome, cobalt and copper, and to know whether subjects with positive skin reaction to nickel would also demonstrate adverse intraoral reaction to a non-precious metal nickel. The patch tests were performed in 81 subjects(male 39, female 42) and nickel sulfate 5% aq., potassium bichromate 0.5% at., cobalt chloride 2% aq., & copper sulfate 1% aq., were used for test allergens. And then the intraoral tests were performed in 16 subjects, 8 subjects with positive allergic skin reaction to nickel and 8 subjects with negative allergic skin reaction. A pure metallic nickel plate was attached to the buccal side of the upper second premolar. The results are as follows : 1. The frequency of nickel sensitivity was 9.9% (2 men, 6 women), cobalt was 4.9% (1 man, 3 women), and chrome was 2.5% (2 men) respectively and there was no positive reaction to copper 2. The positive reactions were 8 of 23 (34.8%) with a history of jewelry allergic reactions and 3 of 58 (5.1%) without a history of jewelry allergic reactions. 3. Three of 8 subjects with positive skin reaction. gave reactions to the metal plates.

• 보존과학연구
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• 통권34호
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• pp.102-108
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• 2013

전라북도에 소재한 유형목조문화재의 단청기록화 사업의 일환으로 송광사 나한전(전라북도 유형문화재 제172호)에 채색된 안료에 대한 X-선형광분석을 실시하였으며, 이들에 대한 색상별 안료의 성분과 보수시기의 동일성을 비교하였다. 분석결과 주성분 및 미량성분을 검토한 결과 나한전에 사용된 안료는 청색은 군청(($3NaAl{\cdot}SiO_4{\cdot}Na_2S_2$), 녹색은 양록($Cu(C_2H_3O_2)_2{\cdot}3Cu(AsO_2)_3$, 주황은 장단($Pb_3O_4$), 황색은 크롬옐로($PbCrO_4$)로 분류되었다. 나한전 외부, 내부의 안료 성분분석으로는 채색 시기를 구별하긴 어려웠다.

• 한국환경보건학회지
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• 제1권1호
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• pp.41-45
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• 1974

A study was carried out to determine the content of Mn and Cr in the ground water in Seoul area, where municipal water supply system was not installed, from Nov. 1 to Nov. 30, 1973. In this study, authors examined the hardness, pH, water temperature and Cl ion to investigate the general conditions of the ground water. For this study, samples were collected from 46 wells which were located in outpart of Seoul city, and Mn and Cr were determined with the Spectronic-20. The following results were obtained: 1) Average value of the ground water conditions of the wells were 13.3$\circ$C in temperature, pH 6.3, hardness 159 ppm and Cl ion 41 ppm. 2) In the manganese concentration, the highest area was Yeongdeungpo-Ku(0.318 ppm), while the lowest area was Sungbuk-Ku(0.065 ppm) and the mean concentration of the whole district was 0.196 ppm. 3) In the chrome concentration, the highest area was Yeongdeungpo-Ku(0.031 ppm), while the lowest area was Dobong-Ku (trace) and the mean concentration of the whole district was 0.012 ppm.

• 유기물자원화
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• 제5권2호
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• pp.47-56
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• 1997

피혁 제조시 발생되는 크롬을 함유한 피혁 고형폐기물인 shaving scraps의 단백질 자원화 가능성을 검토하기 위하여 알카리제로 MgO를 농도별로 처리하여 가수분해시켜 회수한 hydrolyzed protein의 특성은 다음과 같다. MgO 처리에 의한 shaving scrap의 알카리 가수분해방법에서 크롬이 불용화 되는 pH 8.0 이상을 유지하기 위해서는 MgO를 5% 이상 처리해야 하는 것으로 나타났으며, MgO 처리에 따른 alkaline condition하에서 shaving scrap의 용해도는 약 60% 수준으로서 낮았다. MgO 처리에 의해 shaving scraps으로 부터 회수한 hydrolyzed protein의 평균 분자량은 약 80~100 KD이었고, collagen protein을 구성하고 있는 glycine, alanine 및 proline이 대부분을 차지하고 있었으며, 산성 아미노산인 aspartic acid와 glutamic acid도 상당량 함유되어 있는 것으로 나타났다. 무기성분중 Mg, Ca 및 Na는 액체비료의 무기양분으로서는 다소 많은 양이 함유되어 있었으며, Cr은 약 30~40ppm으로서 원시료 (40,000~42,000ppm)에 비해 크게 감소되었다.

• 한국주조공학회지
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• 제35권6호
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• pp.178-184
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• 2015

Due to excellent abrasion resistance the high-chrome white irons are widely used in mining and mineral industries. Minor variation of carbon content in 28% chrome white iron resulted in difference in primarily solidified microstructure. Sub-eutectic (hypoeutectic) composition led to formation of primarily solidified dendrites. Formation of primarily solidified dendrites which were supersaturated with carbon and chrome also caused precipitation of fine secondary carbides that are different from relatively large plate type $M_7C_3$ carbides in the eutectic structure. Small portion of primarily solidified dendrite expected to contribute significantly to the improvement of abrasion resistance of the white iron because the dendrites provided mechanical support to carbides. The relative fraction of primary dendrite increased with reduction of carbon content from the eutectic composition. The increased fraction of primary dendrite increased hardness value of the white irons.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2008년도 추계학술대회 초록집
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• pp.153-154
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• 2008

High velocity oxy-fuel (HVOF) thermal spraying coating has been used widely throughout the last 60 years mainly in defense, aerospace, and power plants. Recently this coating technique is considered as a promising candidate for the replacement of the traditional electrolytic hard chrome plating (EHC) which pollutes the environment and causes lung cancer by toxic hexa-valent $Cr^{6+}$. In this study, two kinds of cermet coatings, WC-CoCr and WC-CrC-Ni, are formed by HVOF spraying. The wear properties of coatings are evaluated comparatively by reciprocating sliding wear tests at $25^{\circ}C$, $250^{\circ}C$ and $450^{\circ}C$ respectively. Wear rates show that WC-CoCr coatings have better sliding wear resistance than WC-CrC-Ni coatings regardless of temperature due to more, compact and homogeneously distributed WC particles, less metal content, Co, Cr rich metallic bindermatrix with higher fracture strength and better adhesive strength with WC particles.

• 생명과학회지
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• 제25권2호
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• pp.164-173
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• 2015

유산 균주들을 신생아 및 성인의 분변으로부터 분리하여 그 중에서도 가장 중금속 흡착능이 크고 중금속에 내성이 있다고 사료되는 균주 KP-3를 선별하여 동정한 결과 Lactobacillus sp.으로 밝혀졌다. 동물 실험에서는 생후 4주령의 Sprague dawley male rat에게 선별한 균주 KP-3를 투여하여 혈액 및 장기 내의 중금속 축적 저해효과가 어느 정도인지 조사하였다. 실험군으로는 SD rat 한 마리당 Lactobacillus sp. KP-3와 중금속 10 ppm을 혼합하여 약 100 ml/day씩 7일간 투여하였다. 대조군으로 중금속과 멸균 생리 식염수를 혼합하여 투여한 군과 Lactobacillus sp. KP-3와 멸균 생리 식염수를 혼합하여 투여한 군, 멸균 생리 식염수 만을 투여한 군으로 분리하여 SD rat 한 마리당 약 100 ml/day씩 7일간 투여하였다. 혈액, 간장 및 신장의 시료를 채취하여 카드뮴(Cd), 크롬(Cr), 납(Pb) 등의 중금속 축적량을 측정하였다. 측정 결과 크롬(Cr)은 신장에 주로 축적되었고, 납(Pb)은 간장과 신장에 주로 많은 축적을 보였고, 실험군인 Lactobacillus sp. KP-3와 중금속을 혼합하여 투여한 군에서는 중금속만을 투여한 군보다 중금속 축적량이 낮은 것으로 나타났다. 카드뮴(Cd), 크롬(Cr), 납(Pb)의 평균 중금속 축적 저해율은 각각 41.8%, 33.4% 44.2%로 나타났다. 특히, 혈액에서의 중금속 축적 저해율은 약 70%로 매우 높게 나타났고 혈액에서의 카드뮴 축적 저해율은 100%로 나타났다. 본 실험에서 탐색하여 최적화된 유산균이라고 생각되는 Lactobacillus sp. KP-3균주는 실험 결과에 의하면 중금속 축적 저해에 효과가 있는 것으로 여겨지며, 또한 유산균이 함유된 식품을 지속적으로 섭취함으로써 체내의 중금속의 축적 억제에 도움이 크게 되리라 생각된다.

• 한국기계가공학회지
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• 제9권2호
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• pp.1-5
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• 2010

According to the high demand of hybrid components, the hybrid materials development and processing technology were increased in the industry field. Although hybrid materials have various machining technologies, the research about them has rarely been proceed. This study is to carry out results about design technology of miniaturized high-speed air spindle and machining characteristics of hybrid materials using that. We studied machining characteristics in Nickel-Chrome alloy(Ni-Cr) according to change rotating speed using miniaturized high-speed air spindle. As the following results, the change of surface shape and roughness was investigated as the processing conditions such as rotating speed of miniaturized high-speed air spindle.

• Journal of information and communication convergence engineering
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• 제4권3호
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• pp.105-107
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• 2006

Amorphous silicon is a kind of optical to electric conversion material with current or voltage type after generating a numerous free electron and hole when it is injected by light. It is very effective technology to make schottky diode by bonding thin film to use optical diode. In this paper, we have fabricated optical diode device by forming chrome silicide film through thermal processing with thin film($100{\AA}$) having optimal amorphous silicon. The optimal condition is that we make a thin film by using PECVD(Plasma Enhanced Chemical Vapor Deposition) to improve reliability and characteristics of optical diode. We have obtained high quality diode by using chrome silicide optical diode from dark current and optical current measurement compared to previous method. It makes a simple process and improves a good reliability.

• 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.