• Journal of Ocean Engineering and Technology
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• v.28 no.6
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• pp.540-545
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• 2014

Multipass self-shielded flux cored arc welding with different heat inputs (1.3–2.0 kJ/mm) was conducted to determine the effects of the heat input on the proportion of the reheated region, impact toughness, and diffusible hydrogen content in the weld metal. The reheated region showed twice the impact toughness of the as-deposited region because of its fine grained ferritic-pearlitic microstructure. With decreasing heat input, the proportion of the reheated region in the weld metal became higher, even if the depth of the region became shallower. Accordingly, the greatest impact toughness, 69 J at −40℃, was obtained for the lowest heat input welding, 1.3 kJ/mm. Irrespective of the heat input, little difference was observed in the hardness and diffusible hydrogen content in the weld metal. This result implies that low heat input welding with 1.3 kJ/mm can be performed to obtain a higher proportion of reheated region and thus greater impact toughness for the weld metal without the concern of hydrogen cracking.

• Journal of Environmental Science International
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• v.13 no.8
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• pp.711-719
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• 2004

The effect of nickel (Ni) on growth and some tolerance strategies with regard to heavy metal tolerance mechanism was investigated in radish (Raphanus sativus) seedlings. The protective effect of histidine on nickel stress conditions was also monitored. The seedling growth decreased with an increase in metal concentrations. The inhibitory effect was more pronounced in the root elongation than in the shoot elongation. Increasing Ni supply showed a progressive increase of Ni concentrations in the roots and shoots. Ni content was higher in the shoots than in the roots. In the presence of nickel, radish exhibited an antioxidative defense mechanism, as evidenced by the elevated malondialdehyde(MDA), showing that nickel is an efficient inducer of lipid peroxidation. Exposure of radish to elevated concentrations of nickel was accompanied by an increase in the proline content. Supplemental histidine in the presence of Ni ameliorated metal-induced growth inhibition and lipid peroxidation. Combinations of Ni and histidine resulted in a significant decline in proline content compared with Ni stress alone, indicating that histidine may provide protection against the adverse effect of Ni stress. From the results it is suggested that histidine is an efficient chelator by complexing metal ion within the plant and may playa role in nickel tolerance implicated in metal detoxification.

• Journal of Welding and Joining
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• v.15 no.4
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• pp.116-125
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• 1997

Electron beam weldability of 9%Ni steels has been investigated to apply EBW to the construction of LNG storage tank. While mechanical properties of welded joints were satisfied by ASTM specification, impact energy of weld metal was as low as 27 - 55J at $-196^{\circ}C$. As the result of Ni wires inserted at the joint to be welded, Ni content of weld metal was increased to about 10%, resulting on the improvement of impact toughness to 110 ~ 120J at $-196^{\circ}C$. This improvement of impact toughness in weld metal was due to the formation of tempered martensite and retained austenite. Above results indicate that, if Ni content of weld metal was increased about 10% by Ni wires addition, electron beam welded 9%Ni steels weld metal had sufficient impact energy necessary for a LNG storage tank.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3183-3189
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• 2010

In order to increase the specific capacitance and energy density of supercapacitors, non-aqueous supercapacitors were prepared using lithium transition-metal oxides and activated carbons as active materials. The electrochemical properties were analyzed in terms of the content of lithium transition-metal oxides. The results of cyclic voltammetry and AC-impedance analyses showed that the pseudocapacitance may stem from the synergistic contributions of capacitive and faradic effects; the former is due to the electric double layer which is prepared in the interface of activated carbon and organic electrolyte, and the latter is due to the intercalation of lithium ($Li^+$) ions. The specific capacitance and energy density of a supercapacitor improved as the lithium transition-metal oxides content increased, showing 60% increase compared to those of supercapacitor using a pure activated carbon positive electrode.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.771-772
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• 2006

Mechanical properties of metal injection molded titanium and titanium alloy parts were investigated in this study. Material powders with low oxygen content and spherical shape were obtained by electrode induction-melting gas atomization which could melt and atomize titanium and titanium alloy bars with no touch on crucible or tundish. Tensile specimens were fabricated from obtained powders by metal injection molding process. Tensile strength of the specimens increases with increasing oxygen content. This result corresponds to a tendency of wrought metal.

• Journal of Korea Foundry Society
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• v.31 no.6
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• pp.354-361
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• 2011

The liquid metal shearing device was constructed and assembled with a commercial high-pressure die-caster in order to induce intensive turbulent shearing force on molten aluminum alloys. The effect of the liquid metal shearing on the microstructure and tensile properties of A356 alloys was investigated with the variation of iron content. The experimental results show that dendritic primary ${\alpha}$-Al phase was effectively modified into a equiaxed form by the liquid metal shearing. It was also found that the needle-like ${\beta}$-AlFeSi phase in a Fe containing A356 alloy was changed into a blocky shape resulting in the improved mechanical properties. Based on the mechanical properties, it was suggested that the iron content in A356 alloy could be more widely tolerated by utilizing the liquid metal shearing HPDC process.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2854-2863
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• 2023

Objective: To present a hybrid approach that incorporates a constrained beam-hardening estimator (CBHE) and deep learning (DL)-based post-refinement for metal artifact reduction in dental cone-beam computed tomography (CBCT). Methods: Constrained beam-hardening estimator (CBHE) is derived from a polychromatic X-ray attenuation model with respect to X-ray transmission length, which calculates associated parameters numerically. Deep-learning-based post-refinement with an artifact disentanglement network (ADN) is performed to mitigate the remaining dark shading regions around a metal. Artifact disentanglement network (ADN) supports an unsupervised learning approach, in which no paired CBCT images are required. The network consists of an encoder that separates artifacts and content and a decoder for the content. Additionally, ADN with data normalization replaces metal regions with values from bone or soft tissue regions. Finally, the metal regions obtained from the CBHE are blended into reconstructed images. The proposed approach is systematically assessed using a dental phantom with two types of metal objects for qualitative and quantitative comparisons. Results: The proposed hybrid scheme provides improved image quality in areas surrounding the metal while preserving native structures. Conclusion: This study may significantly improve the detection of areas of interest in many dentomaxillofacial applications.

• Korean Journal of Environmental Agriculture
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• v.17 no.1
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• pp.48-53
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• 1998

The purpose of this study was to compare heavy metal concentrations in uncontaminated soil with those in soil influenced by industrial activities, and to investigate the relationship between change of heavy metal content and the kind of industry at the Iksan 1st Industrial Complex that has started since 1975. Soils sampled in 0-3㎝ and 3-6㎝ soil depth, respectively were analized for content of Cd, Cu, Ni, Pb and Zn. Change of heavy metal content in soil of the industrial complex were more accumulated 16 to 25% of Cd and Cu, 93% of Pb and Zn, respectively in samples compared with natural soil uncontaminated. But there was no different in Ni content between two soil. Distribution of Cd in soil layer of 0 to 3cm was the highest concentration of 5 ppm more at the textile industries, and then higher at the chemicals and the food processing industries. In 3 to 6㎝ soil layer Cd content was the highest concentration of 5 ppm more at the metal processing industries, and then higher at the textile industries. Cd accumulation in soil was different according to a kind of industry and soil depth. Cu content was the highest value of 400 ppm more in soil layer of 0 to 3cm at the manufacturing electric wires industry area and showed the accumulation phenomenon in soil layer 3 to 6cm at the ohmmeter, machines and electric wires industry area. Ni content was 35 ppm more in soil of the metal plating and processing industries regardless of soil sampling layer. Then it was 25 ppm more in soil of the building stones and semiconductor industries. Pb content was from 400 to 1000 ppm in soil of the chemicals and textiles industries regardless of soil sampling layer. Zn content was 1200 ppm more in soil of the chemicals and silk fabrics industries regardless of soil depth, and then lower in order to soil of leather processing${\le}$metal plating industries. In conclusion, changes of heavy metal kinds and content in soil of this industrial complex area were caused by the type or kinds of industrial activities. Changes of Pb and Zn content in soil were dominated at this area.

• Journal of Food Hygiene and Safety
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• v.9 no.1
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• pp.49-56
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• 1994

This study was carried out to investigate the levels of copper, zinc, manganese, nickel, cadmium and mercury content in breast milk among urban, rural and industrial lactating women in Korea. A total of 59 samples, which were collected from 17 in urban, 20 in rural and 22 in industrial area, and from 21-38 years-old healthy lactating women, were analyzed by Rigaku Mercury Analyzer for mercury, and by atomic absorption apectrophotometry for the other metals. The results are summarized as follows : The mean trace metal contents in breast milk were determined to be 0.34$\pm$0.14 ppm for copper, 2.01$\pm$1.43 ppm for zinc, 8.49$\pm$5.11 ppb for manganese, 7.75$\pm$5.73 ppb for nickel, 1.65$\pm$2.42 ppm for cadmium, 34.45$\pm$26.71 ppb for lead and 0.90$\pm$0.68 ppb for mercury. For the trace metal content in breast milk by area, the highest of copper, zinc, cadmium and mercury content were in urban, the highest of manganese content was in industrial, and the highest of nickel and lesd content were in rural. For copper, zinc, manganese and lead content in breast milk by lactation period, the highest levels were found in under 4 weeks after lactating, and subsequently the levels declined as lactation progressed, but the levels of zinc and manganese content increased from over 25 weeks after lactating. For cadmium and mercury content in breast milk by lactation period, the lowest levels were found in under 4 weeks after lactating, the highest levels were found in 5-12 weeks after lactating, and subsequently the levels declined as lactation progressed.For nickel content in breast milk by lactation period, the highest level was in 13-24 weeks after lactating, the lowest level was in 5-12 weeks after lactating.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.37-38
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• 2012

Two catalyst systems with different content of precious metal coated on DOC are carefully tested in a diesel engine to investigate the emission characteristics of $NO_2$. Three types of experiment methods ($NO_2$ conversion test, ETC mode test, and BPT test) are applied to compare the performance of the two catalyst systems. All the experimental results consistently indicate that it is possible to satisfy $NO_x$ regulation by properly lowering the content of precious metal without the loss of PM removal performance.