• 한국인터넷방송통신학회논문지
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• 제18권6호
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• pp.107-112
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• 2018

콘포멀 스프레이 코팅으로 형성한 EMI 차단막으로 차폐효과(SE)를 얼마나 개선할 수 있는지 연구하였다. 차단막을 형성하는데 사용한 재료는 도체 분말을 아크릴계 바인더에 혼합한 금속-레진 복합재료이며, 금속분말로는 은(Ag)과 니켈(Ni)을 비교하였다. 재료의 점도는 400 cPs와 100 cPs에서 차폐성능을 비교하였다. 차단막의 두께는, 은의 경우 20 um에서 50 um, 니켈의 경우 60 um에서 120 um로 만들어 비교하였다. 차폐효과의 측정은 동축형 표준 측정기를 이용하여 ASTM D4935 방법으로 수행하였다. 니켈 시료보다 은 시료의 차폐효과가 우수했다. 차폐효과는 차단막 두께와 비례해 증가하지만 35 um 이상에서 더 이상 증가하지 않는다는 사실도 관찰하였다. 가장 차폐효과가 좋은 경우는 35 um 두께 은 시료 차단막으로, 63 dB의 차폐효과가 측정되었다.

• 한국환경보건학회지
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• 제20권2호
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• pp.55-63
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• 1994

While environmental pollution being developed, there have been some cases that residents on certain parts of Seoul area have cultivated vegetables in a small scale, and consumed the produce of theirs thinking them not polluted. Therefore the need for study about whether those vegetables and soil were polluted was growing. In this study, Seoul area (Tobong-dong, Chang-dong, Wolgyedong, P'il-dong, Oksu-dong, and Karibong-dong) and Kyanggi area (Changhang, P'och'an, Kap'yang, Yangp'y~ng) where pollution was thought to be less severe than that of the former were selected for the sampling area. Cabbage, pumpkin and young pumpkin were sampled and dried to be analyzed the contents of Cd, Cr, Cu, Ni, Pb, Zn, and moisture content was also analyzed. And at the same time 0.1 N-HCl soluble heavy metal content of soil was measured, and the results obtained were descrived as follows. Heavy metal contents of soil in Seoul and Kyonggi were Cd 0.184 ppm, 0.118 ppm, Cr 2.355 ppm, 0.441 ppm, Cu 29.16 ppm, 3.331 ppm, Ni 1.650 ppm, 0.829 ppm, Pb 26.77 ppm, 4.696 ppm, Zn 57.47 ppm, 14.94 ppm respectively. Heavy metal contents of cabbage in Seoul and Kyonggi were Cd 0.407 ppm, 0.241 ppm, Cr 0.388 ppm, 0.402 ppm, Cu 6.853 ppm, 4.486 ppm, Ni 1.479 ppm, 0.878 ppm, Pb 0.812 ppm, 0.258ppm, Zn 112.2 ppm, 54.86ppm respectively. Heavy metal contents of pumpkin in Seoul and Ky6nggi were Cd 0.011 ppm, 0.011 ppm, Cr 0,262 ppm, 0.197 ppm, Cu 3.302 ppm, 2.539 ppm, Ni 0.717 ppm, 0.369 ppm, Pb 0.257 ppm, 0.083 ppm, Zn 28.75 ppm, 14.01 ppm respectively. Correlation between heavy metal contents of soil and those of vegetables was represented high as a whole. In all heavy metals cabbage had higher values of concentrations than those of pumpkin (p<0.001). Concentrations of young pumpkin were higher than those of big pumpkin. It was probably due to the fact that young pumpkin containing not only inner part of pumpkin but also seeds was used as a sample. When classified by region, relatively high concentrations were observed in the samples of Karibong-dong, and in the sample of Jungtang riverside Cd was higher, and in the sample of Namsan Pb was higher than any other district.

• The Journal of Advanced Prosthodontics
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• 제9권3호
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• pp.176-181
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• 2017

PURPOSE. The purpose of this study was to evaluate the marginal and internal gaps of Ni-Cr and Co-Cr copings, fabricated using the dental ${\mu}-SLA$ system. MATERIALS AND METHODS. Ten study dies were made using a two-step silicone impression with a dental stone (type IV) from the master die of a tooth. Ni-Cr (NC group) and Co-Cr (CC group) alloy copings were designed using a dental scanner, CAD software, resin coping, and casting process. In addition, 10 Ni-Cr alloy copings were manufactured using the lost-wax technique (LW group). The marginal and internal gaps in the 3 groups were measured using a digital microscope ($160{\times}$) with the silicone replica technique, and the obtained data were analyzed using the non-parametric Kruskal-Wallis H test. Post-hoc comparisons were performed using Bonferroni-corrected Mann-Whitney U tests (${\alpha}=.05$). RESULTS. The mean (${\pm}$ standard deviation) values of the marginal, chamfer, axial wall, and occlusal gaps in the 3 groups were as follows: $81.5{\pm}73.8$, $98.1{\pm}76.1$, $87.1{\pm}44.8$, and $146.8{\pm}78.7{\mu}m$ in the LW group; $76.8{\pm}48.0$, $141.7{\pm}57.1$, $80.7{\pm}47.5$, and $194.69{\pm}63.8{\mu}m$ in the NC group; and $124.2{\pm}52.0$, $199.5{\pm}71.0$, $67.1{\pm}37.6$, and $244.5{\pm}58.9{\mu}m$ in the CC group. CONCLUSION. The marginal gap in the LW and NC groups were clinically acceptable. Further improvement is needed for CC group to be used clinical practice.

• 자원리싸이클링
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• 제29권5호
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• pp.55-63
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• 2020

묽은 염산용액에서 이온성액체에 의한 코발트(II)와 니켈(II)의 분리를 조사하기 위해 이온성액체의 종류와 농도 및 수상의 초기 pH를 변화시켜 추출실험을 수행했다. 본 논문에서는 유기인산(D2EHPA, PC88A, Cyanex 272, Cyanex 301)을 Aliquat 336과 반응시켜 제조한 이온성액체와 Aliquat 336의 염소이온을 SCN과 치환한 이온성액체를 사용했다. 세 종류의 이온성액체(ALi-D2, ALi-PC, ALi-CY272)에 코발트(II)가 니켈(II)보다 추출이 잘 되었으며 평형 pH가 초기 pH보다 높았다. ALi-CY301의 경우 코발트(II)와 니켈(II)의 선택도는 추출조건에 의존했다. 또한 상기 이온성액체에 TBP의 첨가가 두 금속의 추출에 미치는 영향도 조사했다. 추출제로 ALi-SCN를 사용하는 조건에서 코발트(II)가 선택적으로 추출되어 두 금속을 완전히 분리하는 것이 가능했다.

• 한국환경보건학회지
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• 제27권1호
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• pp.88-92
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• 2001

The simultaneous analytical method for 37 residual pesticides was developed by a gas chromatography with $^{63}$ Ni electron capture detector. Pesticides added in soybean sample were extracted with 70% acetone in water and methylene chloride in oder, and then cleaned up via open-column apparatus packed with florisil and alumina N. The Ultra-2 fused capillary column was used to separate the products. The resolution between the last isomeric peak of cypermethrin (56.398 min) and the first isomeric peak of flucythrinate (56.421 min) was not satisfactory and the last isomeric peak of fenvalerate(58.783 min) and the first isomeric peak of fluvalinate(58.835 min) was overlapped. Except for $\alpha$-BHC, dichlofluanid, captan, and captafol, most recoveries were showed over 70%.

• Wind and Structures
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• 제4권1호
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• pp.63-72
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• 2001

This paper presents results of a study on wind loads and wind induced dynamic response of bridge jointed twin-towered buildings. Utilizing the high-frequency force balance technique, the drag and moment coefficients measured in wind tunnel tests, and the maximum acceleration rms values on the top floor of towers, are analyzed to examine the influence of building's plan shapes and of intervals between towers. The alongwind, acrosswind and torsional modal force spectra are investigated for generic bridge jointed twin-towered building models which cover twin squares, twin rhombuses, twin triangles, twin triangles with sharp corners cut off, twin rectangles and individual rectangle with the same outline aspect ratio as the twin rectangles. The analysis of the statistical correlation among three components of the aerodynamic force corroborated that the correlation between acrosswind and torsional forces is significant for bridge jointed twin-towered buildings.

• 자원환경지질
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• 제32권1호
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• pp.63-72
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• 1999

In order to examine the contamination levels of trace elements in stream sediments in the Chungnam coal mine area, stream sediment and water samples were collected and analyzed for trace elements. The pH of stream water was neutral or weak-alkaline and the mobility of metal in stream sediments was supposed to be low. From the result of cluster analysis, non-polluted sampling stations can be distinguished from polluted sampling stations influenced by mining activities. The trace element concentrations in sediments from non-polluted zone were considered to be the natural backround concentrations of this area. The trace element concentrations in sediment samples from the mining area were higher than those from non-polluted area, and contaminated area of enriched trace element levels need to be properly managed. From the results of discriminant and regression analyses, concentrations of Cd, Cu, Pb AND zN and predicted values of Be, Mo, and Ni in Chungnam coal mine area were found to be lower than those in metal mining areas in Korea.

• 한국식품영양학회지
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• 제12권3호
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• pp.246-251
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• 1999

The purposed of this study was to investigate the efficient recycling of food waste according to the restaurants type. To the investigated of characteristic of food wastes in different types of restaurants we were collected the sample of 60 as Korean 35 Chinese 10 Japanese 5 Western 5 Flour 5 in Swoon. The average water content of food waste was 79.9% and Korean restaurant was 80.3% which was hig-her than that of any other serving type. On the examination of a organic matter content of food waste according to the season crude fiber was higher in may and July crude protein content was higher in January and march than that other seasons. The average pH of food waste was 4,74 C/N ratio was 15.8 and the average cation content was K 0.57% Ca 0.39% Mg 0.22% NaCl 3.36% respectively The aver-age concentration of Fe, Zn, Pb, Cu, Cr, Cd Ni were 154.37 mg/kg 24.79 mg/kg 0.27 mg/kg 5.63 mg/kg 5.49 mg/kg, 0.31mg/kg 1.07mg/kg respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.430-430
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• 2008

열화학기상 증착법으로 2원계 합금인 Invar 36(63wt% Fe, 37wt% Ni)을 이용하여 다중벽 탄소나노튜브를 360도의 저온에서 까지 합성이 가능함을 확인하였다. 촉매와 Si 기판과의 silicide형성을 막기 위한 Ti층의 두께가 증가함에 따라서 탄소나노튜브의 길이가 잘 자라는 것을 확인하였으며, 미량의 물이 첨가 되었을 경우 탄소나노튜브의 길이 성장에 큰 변화가 있음을 확인하였다. 또한 물을 포함하는 실험에서는 촉매인 Invar36의 두께가 0.5 nm 일 때에 비하여 0.25 nm 두께에서 물에 대한 영향이 더 크게 나타남을 SEM 사진을 통해 확인할 수 있었다.

• Archives of Pharmacal Research
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• 제15권2호
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• pp.109-114
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• 1992

For the risk assessment of human exposure to volatile halogenated hydrocarbons, a dynamic purge trap/on-column cryofocusing method using capillary gas chromatograph-$^{63}Ni$ electron capture detector and thermal desorption unit was applied to analyze the free forms, metabolites of 1, 1, 2-trichloroethylene and 1, 1, 2, 2-tetrachloroethylene. The urine sample was diluted with distilled water, hydrolyzed and sealed. Then the inert gas was infused to purge out free 1, 1, 2-trichloroethylene, free 1, 1, 2, 2-tetrachloroethylene and urichloroethanol. These compounds were trapped to $Tenax^R$ / GC-gas trap device throughout clean up tube. Being undertectable to gas chromatograph directly, trichloroacetic acid was methyl esterificated and trapped in the manner above mentioned. The optimal incubation time to get best recovery of methyl ester was 4 hours at $60^circ$C. The concentrations of free volatile halogenated hydrocarbons and their metabolites in urine were obtained of free volatile halogenated hydrocarbons and their metabolites in urine were obtained from 5 healthy volunteers. This analytical method is expected to make the biological monitoring more precise and convenient.