• Journal of Welding and Joining
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• 제6권2호
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• pp.40-46
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• 1988

The effect of heat input on the content of residual .delta.-ferrite and the hot cracking susceptibility in the austenitic stainless steel overlaid on the carbon steel was studied in the range of heat input from 7.5 to 15.1 KJ/cm. Present study shows that residual .delta.-ferrite content in the overlay is mainly determined by the dilution of the base metal (carbon steel) which is in turn affected by heat input, i.e. the amount of dilution decreases as heat input increase. Accordingly, higher heat input results in a substantial increase in Cr equivalent but a little increase in Ni equivalent due to the less dilution of carbon from base metal. This fact can explain the result obtained in this study, i, e, the higher content of .delta.-ferrite in the weld deposit made with higher heat input. This in turn causes more resistant overlaying weld metal to hot cracking.

• Environmental Analysis Health and Toxicology
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• 제14권4호
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• pp.155-163
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• 1999

Heavy metal accumulation in living organisms through food-wed can give serious damage on physiological responses for vital activities. The initiation of heavy metal supposed to begin from the bio-accumulation of plants. To establish basic data fur heavy metal contents in plants at the area without artificial contamination, both woody and herb plants at Mt. Kwang-Duk were studied. The content of heavy metals in various organs of plants were analyzed by ICP. The range of heavy metals in plants for Al, As, Cd, Co, Cr, Cu, Fe. Mn, Pb, Se and Zn were 1.019∼257.200ppm, O∼2.929ppm, 0∼0.079ppm, 0∼0.054ppm, 0.023∼3.007ppm, 0∼1.997ppm, 2.031∼148.500ppm, 1.069∼51.320ppm, O∼126.900ppm, 0.708∼4.927ppm and 0.846∼4.949ppm, respectively. The amount of heavy metals in plants are much less than that of soil except some species. In woody plants, it was detected that the metal contents of leaves were higher than that of stems especially in case of Al and Fe with statistical significance. There were significant differences between shoots and roots of herb plants in metal content of Al, Co and Fe. Those metals have more accumulated in roots comparing with shoots. Some species of plants had shown the difference tendency of heavy metal accumulation. Generally, most species had not exceeded over twice of mean value each other, and had various difference according to the kinds of heavy metals.

• 대한치과보철학회지
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• 제27권1호
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• pp.143-179
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• 1989

To observe the bonding behavior of palladium-based alloys to porcelain; 1. Pd-Co binary alloy with the higher cobalt content, 2. Pd-Co binary alloy with the lower cobalt content, 3. Pd-Ag-Sn ternary alloy, 4. Pd-Ag binary alloy, 5. Pd-Cu-Au ternary alloy and 6. Pd-Cu binary alloy were made as 6 groups of experimental alloys. Each group of alloy was divided into 4 sub-groups such as one sub-group that was not degassed and three sub-groups that degassed for 5 minutes, 10 minutes and 15 minutes. On each specimen, weight changes after degassing, morphological changes of oxide layer by changing the degassing time, compositional changes at metal-ceramic interface and bond strength of metal-ceramic measured with planar shear test were observed and compared. The results of the present study allow the following conclusions to be drawn: 1. The alloy showing the greatest bond strength was Pd-Cu alloy without gold and bond strength was decreased by alloying gold to them. 2. Although Pd-Co alloy showed the most prominent oxidation behavior, bond strength of them to porcelain was not greatly high by the formation of porosities at metal-ceramic interfaces. 3. Likewise tin, cobalt formed the peaks on line profiles at metal-ceramic interface, however copper did not exhibit such peaks on line profiles. 4. Mainly, oxide layer on Pd-Co alloy was composed with cobalt, and for Pd-Co alloy with higher cobalt content the rise of bond strength was not significant by increased degassing time. 5. On Pd-Ag alloy not containing tin, during degassing for 15 minutes silver content was increased at metal-ceramic interface. 6. As an oxidized element, tin formed the oxide layers that widen their area by increasing the degassing time, while cobalt and copper showed the morphological changes of particle or crystal on oxide layer.

• Journal of Welding and Joining
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• 제19권6호
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• pp.614-621
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• 2001

A study was carried out to determine the solidification cracking susceptibility of Ni-base superalloy as a function of Fe content in base metal. Three kinds of Ni-base superalloys with three different levels of Fe content were used. The solidification cracking susceptibility was evaluated by the Trans-Varestraint test at four different strain levels. Quantitative analysis of crack revealed that the solidification crack length and the temperature range in which hot cracking occurred in fusion zone (Brittle Temperature Range, BTR) decreased with a decrease in Fe content. Further, the thermo-calc data indicated that the solidification temperature range also decreased with decreasing Fe content. From these results, it was deduced that the improvement of the solidification cracking susceptibility with decreasing Fe content was attributed to the decrease of the solidification temperature range.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.548-551
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• 2004

For the improvements in high transmittance, one of the most important factors of transparent dielectric is pore contents and pore size. This study have investigated the effect of frit size on the transmittance of zinc-boric system with a Pb-free composition. A mixed glass paste was used for thick films, which were made by screen printing methods on a glass substrate (PD200). These dielectric layers were measured for surface roughness, pores content and transmittance. The results show that increase of pore size and content have detrimental effects on the transmittance of films compared to those found in the PbO system.

• 한국환경보건학회지
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• 제22권2호
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• pp.69-82
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• 1996

The samples for testing have been collected from Kangdong-myon, Nongso-myon, Beomseo-my on, and Cheongryang-myon in Ulju-Ku, Ulsan-city from July 1994 to March 1995 in order to grasp status of trace metals contained in some rice, soybean and soils, and to provide references in establishing their standard 96 collected samples(48 for cereals and 48 for soils) have been tested to measure levels of Hg, Pb, Cd, Cu, and Zn through methods of trace metal containing analysis and heavy metal analysis. moisture content was also analyzed. And at the same time 0.1N-HCl soluble heavy metal content of soil was measured. The average Hg containing level of samples is 0.006 ppm for cereal and 0.062 ppm for soil, Pb is 0.302 ppm for cereal and 1.137 ppm for soil, Cd is 0.012 ppm for cereal and 0.027 ppm for soil, Cu is 2.01 ppm for cereal and 0.885 ppm for soil, and Zn is 7.853 ppm for cereal and 2.366 ppm for soil.

• 한국분말재료학회지
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• 제4권3호
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• pp.196-204
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• 1997

Joining of AIN ceramics to W and Cu by active-metal brazing method was tried with use of (Ag-Cu)-Ti alloy as insert-metal. Joints were produced under various conditions of temperature, holding time and Ti-content in (Ag-Cu) alloy Reaction and microstructural development in bonded interface were investigated through observation and analysis by SEM/EDS, EPMA and XRD. Joint strengths were measured by shear test. Bonded interface consists of two layers: an insert-metal layer of eutectic Ag- and Cu-rich phases and a reaction layer of TiN. Thickness of reaction layer increases with bonding temperature, holding time and Ti-content of insert-metal. It was confirmed that the growth of reaction layer is a diffusion-controlled process. Activation energy for this process was 260 KJ/mol which is lower than that for N diffusion in TiN. Maximum shear strength of 108 MPa and 72 MPa were obtained for AIN/W and AIN/Cu joints, respectively. Relationship between processing variables, joint strength and thickness of reaction layer was also explained.

• Journal of Welding and Joining
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• 제2권2호
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• pp.62-69
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• 1984

In this study, cold crack susceptibility of high strength steel (ABS EH32 Steel) welded zone with shielded metal are welding was investigated by tensile restraint cracking test method. Effects of diffusible hydrogen content on root cracking, lower critical stress, crack initiation and fracture mode, hardness value distribution of welded zone and fractograph were mainly investigated. Following conclusions are made: 1. In the view of the lower critical stress level, wet electrode, containing much diffusible hydrogen content shows lower value than dried electrode. 2. Hardness value(Hv 5kg) in Heat Affected Zone of wet electrode is higher than that of dried electrode caused by hydrogen embrittlement. 3. In the case of wet electrode, root crack is initiated and propagated in Heat Affected Zone and then propagated to weld metal, but using of dried electrode, root crack is initiated in Heat Affected Zone and propagated to weld metal without propagating in HAZ. 4. For wet electrode, quasi-cleavage fracture mode is majorly observed on the fracture surface of HAZ and partially of weld metal due to hydrogen embrittlement.

• 한국토양비료학회지
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• 제28권2호
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• pp.130-134
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• 1995

무연탄회(無煙炭灰)와 유연탄회(有煙炭灰)를 식양토(埴壤土)에서는 12톤/10a씩 1년 및 3년간(年間) 처리(處理)하고, 사양토(砂壤土)에서는 2년간(年間) 처리(處理)된 토양내(土壤內)의 토심(土深) 30cm, 60cm, 100cm에서의 침투수중(浸透水中) 중금속(重金屬) 함량(含量)을 조사(調査)한 결과(結果)는 다음과 같다. 1. 식양토(埴壤土) 논에서 무연탄회(無煙炭灰) 처리(處理)로 Zn는 무처리(無處理)보다 증가(增加)되었으며 토심(土深)이 깊을수록 증가(增加)되는 경향이나 유의성(有意性)은 없었다. 2. 식양질(埴壤質) 논에서 석탄회(石炭灰)를 3년간(年間) 연용(連用)한 결과(結果), 석탄회(石炭灰) 처리(處理)로 Pb와 Zn는 석탄회(石炭灰) 처리(處理)로 무처리구(無處理區) 보다 다소 증가(增加)되었고 토심별(土深別)로는 Pb만이 100cm 토심(土深)에서 증가(增加)되었으나, 기타 성분(成分)은 석탄회처리구(石炭灰處理區)가 무처리구(無處理區) 보다 감소(減少)되었다. 3. 사양질(砂壤質) 논에서 석탄회(石炭灰)를 2년간(年間) 처리(處理)로 무연탄회(無煙炭灰) 처리(處理)에서는 Cd, Ni, Mn은 유의성(有意性)있게 증가(增加)되었고 심토(深土)에서도 증가(增加)되었으나 기타 성분은 유사하거나 감소되었다.

• 유기물자원화
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• 제4권1호
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• pp.23-31
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• 1996

가정에서 분리수거한 쓰레기와 혼합쓰레기 및 퇴비화 과정중에 있는 쓰레기의 중금속 농도를 측정하였다. 카드뮴의 농도는 봄철에 8 mg/kg 쓰레기, 겨울철에 13 mg/kg 쓰레기였다. 중금속의 농도는 월별로 큰 차이를 보였으며 1월과 2월, 4월, 5월에는 카드뮴의 함량이 부산물 퇴비의 기준인 5 mg/kg 쓰레기의 농도를 초과하였다. 가정쓰레기가 혼합되기 전 분리수거된 음식쓰레기의 퇴비화 과정중에 카드뮴의 함량을 측정한 바, 봄철과 겨울철에 부산물 퇴비화의 기준치를 초과하였다. 분리수거된 가정쓰레기에 수분조절제로 첨가된 석탄회는 퇴비중의 중금속 함량을 낮추는 효과가 있었다. 소형 퇴비화 용기에서 1개월 퇴비화한 음식쓰레기를 야외에서 야적하여 숙성시켰는데, 이 기간동안에 중금속의 축적은 일어나지 않았다.