• 대한방사성의약품학회지
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• 제4권2호
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• pp.80-84
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• 2018

$[^{13}N]$Ammonia or $[^{13}N]NH_3$ is one of the most widely used PET tracer for the measurement of MBF. To produce $[^{13}N]NH_3$, devarda's alloy which contains aluminum, copper and zinc is used for the purpose of reduction from $^{13}N$-nitrate/nitrite to $[^{13}N]NH_3$. Since aluminum has neurotoxicity and renal toxicity, the amount of it should be carefully limited for the administration to the human body. Although USP and EP provide a way to identify the aluminum ion concentration, there are some difficulties to perform. Therefore, we tried to develop the modified method for verifying aluminum concentration of test solution. We compared color between test and standard solutions using chrome azurol S in pH 4.6 acetate buffer. We also tested color change of test and standard solutions according to pH, amounts and the order of reagent and time difference These results demonstrated that the color change of the solution can reflect quantitatively measure aluminum ion concentration. We hope the method is to be used effectively and practically in many sites where $[^{13}N]NH_3$ is produced.

• 한국결정성장학회지
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• 제8권4호
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• pp.587-591
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• 1998

마이크로 웨이브를 보조 여기원으로 사용한 직류 magnetron 스퍼터링법으로 Aluminum이 2wt% 포함되어 있는 Zn:Al 합금타겟을 사용하여 AZO(Aluminum doped zinc oxide) 투명 전도막을 제막하였고 그 영향을 조사하였다. 타겟인가 전압이 420V에서 증착된 막의 투과율, 비저항 그리고 증착속도는 각각 50~70%, $5.5{\times}10^{-3}{\Omega}$cm 그리고 6,000$\AA\textrm{mm}^2$/J 이었다. 이 막을 40$0^{\circ}C$에서 30분간의 열처리하면 광투과율은 80% 이상으로 열처리전에 비해 향상되었으며 전도도는 2배 이상 향상되어 비저항값이 $2.0{\times}10^{-3}{\Omega}$cm인 막을 얻을 수 있었다.

• Transactions on Electrical and Electronic Materials
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• 제12권5호
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• pp.218-221
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• 2011

We modified the optical properties of the $CuInS_2$ nanocrystal (NC) by alloying. Nanocrystals (NCs) with alloyed cores were synthesized by refluxing the as-synthesized $CuInS_2$ NCs with a mixture of cadmium acetate, zinc acetate and palmitic acid. The shift in emission wavelength of the NCs after shell layer formation was minimized by alloying. The photoluminescence (PL) spectra showed significant reduction of emission intensity. A detailed study on the emission process of NCs implies that the formation of shell layers with small lattice mismatch minimized the mismatch strain generated from the shell layers in contrast to core alloyed NCs. In particular, time-resolved PL spectra of the NCs showed a significant increase in the lifetime of excited carriers by modifying the band alignment of the NCs by modifying the shell composition.

• 분석과학
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• 제7권2호
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• pp.155-164
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• 1994

전형적인 Grimm형 방전관을 제작하고 고주파 방전에 의한 금속 및 세라믹시료 분석에 적용하였다. 금속 알루미늄과 알루미나에 대해 방출 스펙트럼을 관찰하였고 방전에 미치는 고주파의 전력과 알곤 기체의 압력에 대한 영향을 관찰하였으며, 시료와 접촉된 전극에 나타나는 DC-bias voltage를 확인하였다. 또한 SEM 사진을 관찰함으로써 rf-sputtering에 의한 알루미나 표면의 미세구조를 확인하였다. 저합금강(BAS 404-405) 중의 망간성분과 황동시료(NIST 1108-1117) 중의 아연성분에 대해 검량곡선을 작성한 결과 양호한 직선성을 보여 주었다.

• 한국정밀공학회지
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• 제17권7호
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• pp.124-131
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• 2000

Rapid Prototyping(RP) models are no longer used only for design verification. Currently, parts built utilizing layer manufacturing technology can be employed as functional prototypes and as patterns or tools for different manufacturing processes such as vacuum casting, investment casting, injection molding, precise casting and sand casting. This trend of Rapid Prototyping application meets the requirement of concurrent engineering and its range covers a more spreaded area. The aim of this paper is saving the manufacturing lead time and cost of plastic parts having hollow space shapes used by prototype-car. Using rapid prototype patterns, made by the Selective Laser Sintering(SLS) technique, a new approach of manufacturing resin-based blow mold is discussed. It has a great potential fur making prototype-car parts with the batch size of under 200 parts, in case of rapid modification due to a subsequent design changes in developing stage. So, the process proposed in this research shows reduction of process time and manufacturing cost when compared with the conventional process such as a Zinc Alloy fur Stamping(ZAS) mold.

• Corrosion Science and Technology
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• 제10권6호
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• pp.199-204
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• 2011

Hot dip metallic coated steels like as galvanized (GI), zinc-aluminium (GL) and aluminium coated steels are mostly used where corrosion resistance is needed. There are two kinds (type 1 and type 2) of aluminium coated steel being commercially used among them. Type 1 aluminium coated steel is coated with an Al-5~11 wt%Si alloy and Type 2 aluminium coated steel consists of commercially pure aluminium. Type 1 Al coated steel is generally used in automotive components and electrical appliances while type 2 aluminium coated steel is mainly used in construction applications such as building cladding panels, air conditioning and ventilation system. In this study, Type 1 aluminium coated steels have tested by accelerated conditions (salt spray or corrosive gas) and outdoor exposure condition in order to understand their corrosion behaviour. Due to the distinct corrosion mechanism of Al which exposes to the severe chloric condition, Salt Spray Test cannot predict the ordinary atmospheric corrosion of Al based coated materials. In addition, the test results and their corrosion feature of Al coated steel sheets will be discussed comparing with other metallic coated steel sheets of GI and GL.

• 보존과학회지
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• 제1권1호
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• pp.27-39
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• 1992

Metallurgical studies of the bronze artifacts excavated from Miruksa Temple were performed by chemical analysis and metallographic observation. Alloy systems of the bronze artifacts were classified into two groups of Cu-Sn and Cu-Sn-Pb, according to the items. The contents of impurities such as Sb, As, Ni and Fe in bronze artifacts are within the limiting range of the mod ern standard bronze castings. Chemical compositions of the kitchen utensils such as bronze vessels and dishes in the Unified Silla dynasty, are in the follow ing range, Cu : 74.8-79.4% and Sn : 18.6-21.1%. Chemical composition of the Buddha-image in Koryo dynasty are 820Cu-7.0Sn-10.3Pb, showing increased Pb content and decreased Sn content. The results of chemical analysis suggest that the chemical compositions were good controlled. Any casting defects such as voids and shrinkage holes are not found microscopically, indicating high casting skill. Zinc atoms are not contained in the all bronze artifacts of Miruksa Temple site. This is the common facts founded in the east asian bronze artifacts of Korea, China and Japan. It is comparable with the European bronze of Cu-Sn-Pb-Zn system, after the Middle Age.

• 한국주조공학회지
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• 제19권5호
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• pp.403-409
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• 1999

Mg-Zn-Zr ternary alloys containing 6wt% Zn and (0, 0.4, 0.6)wt% Zr, which is added for grain refinement, can be cast into complex shape by squeeze casting. The influence of Zn and Zr as additional elements on microstructure and mechanical characteristics is investigated by OM, SEM, WDX, XRD and microvickers hardness measurement. The microstructure of Mg-Zn-Zr alloys consists of primary ${\alpha}-Mg$ and MgZn eutectic compound between dendrites. The grain size is decreased from $136{\mu}m$ to $97\;{\mu}m$ by Zr addition, resulting in that the hardness is increased from 42Hv to 59Hv. Furthermore, the grain size is changed to $83{\beta}$ and the hardness is increased to 65Hv by additional infiltration pressure. These results indicate that the Zr addition and additional infiltration pressure are effective for grain refinement acting as an important factor to increase the hardness. The increment in hardness by the Zr addition is slightly larger than that by the additional infiltration pressure.

• 한국표면공학회지
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• 제27권4호
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• pp.207-214
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• 1994

In consideration of global environmental protection and fuel saving, aluminum alloy sheets for auto body panels such as hood, fender etc., are expected one of the most promising materials for weight saving of cars. The chemical conversion coating is required to prevent the filiform corrosion occurring on painted aluminum. However the conventional process for the composited material mixed with aluminum and steel is complexs; aluminum part is chromated and assembled to the body, and then the steel body undergoes Zn phosphating. In order to overcome the low productivity due to the complex process and the environmental problem with a conventional process, a simultaneous zinc phosphating process for alsuminum and steel in an assembled condition is demanded. Newly developed phosphate solution has been investigated to characterize the phosphating behavior under various conditions. The optimum conditions of the phosphating solution for the application of the paint treatment derived as follows : about 0.3 for the ratio of Zn to $PO_4$, , 200~500 ppm for the concentration of fluoride ion, and 2.5~4.0 for pH. The concentration of dissolved aluminum ion must be kept below 2--ppm and suitable accelerator is found to be a mixture of 1g/$\ell$ $NO_2\;^-$, and 6g/$\ell$ $NO_3\;^-$.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.266-267
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• 2012

아연계 합금도금강판은 내식성이 향상되는 반면 아연 이외의 원소 성분에 의해 고온다습에서 변색되기 쉽기 때문에 이를 억제하기 위한 후처리 기술이 필요하다. 또한, 아연계 합금도금 강판이 자동차 부품으로 적용되기 위해서는 변색 억제를 위해 처리한 후처리제가 쉽게 제거되어 인산염처리 공정에서 도금 표면에 인산염결정이 용이하게 형성되어야 한다. 본 연구에서는 건식공정으로 제작된 아연계 합금도금 강판에 우레탄계 알칼리 후처리제를 도포하고, 고온다습 환경에서의 변색 억제 특성과 적정 부착량에서의 인산염처리 및 전착도장 특성에 대해 평가하였다. 두 형태의 후처리제는 건식 아연계 합금도금 강판에 도포 직후 표면에 간섭색을 나타내었으며, 첨가제를 통해 간섭색 제어가 가능하였다. 또한, 두 형태의 후처리제 모두가 고온다습 환경에서 무처리 강판에 비교하여 월등히 우수한 변색 억제 효과를 보였으며, 인산염처리 및 전착도장이 양호하게 얻어지는 것을 알 수 있었다.