• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.49-59
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• 1984

Optimizing investigation of characteristics of underwater welding by a gravity type arc welding process was experimentally carried out by using six types of domestic coated welding electrodes for welding of domestic marine structural steel plates (KR Grade A-1, SWS41A, SWS41B,) in order to develop the underwater welding techniques in practical use. Main results obtained are summarized as follows: 1. The absorption speed of the coating of domestic coated lime titania type welding-electrode became constant at about 60 minutes in water and it was about 0.18%/min during initial 8 minutes of absorption time. 2. Thus, the immediate welding electrode could be used in underwater welding for such a short time in comparison with the joint strength of in-atmosphere-and on-water-welding by dry-, wet-or immediate-welding-electrode. 3. By bead appearance and X-ray inspection, ilmenite, limetitania and high titanium oxide types of electrodes were found better for underwater-welding of 10 mm KR Grade A-1 steel plates, while proper welding angle, current and electrode diameter were 6$0^{\circ}C$, above 160A and 4mm respectively under 28cm/min of welding speed. 4. The weld metal tensile strength or proof stress of underwater-welded-joints has a quadratic relationship with the heat input, and the optimal heat input zone is about 13 to 15KJ/cm for 10mm SWS41A steel plates, resulting from consideration upon both joint efficiency of above-100% and recovery of impact strength and strain. Meanwhile, the optimal heat input zone resulting from tension-tension fatigue limit above the base metal's of SWS41A plates is 16 to 19KJ/cm. Reliability of all the empirical equations reveals 95% confidence level. 6. The microstructure of the underwater welds of SES41A welded in such a zone has no weld defects such as hydrogen brittleness with supreme high hardness, since the HAZ-bond boundary area adjacent to both surface and base metal has only Hv400 max with the microstructure of fine martensite, bainite, pearlite and small amount of ferrite.

• Clean Technology
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• v.24 no.1
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• pp.77-84
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• 2018

In this study, $Li_4Ti_5O_{12}$ anode materials for lithium ion battery were synthesized by dry ball-mill method. Polyvinyl chloride (PVC) as a carbon source was added to improve electrochemical properties. When the PVC was added after $Li_4Ti_5O_{12}$ formation, the spinel structure was well synthesized and it was confirmed by X-ray diffraction (XRD) experiments. When the carbon material was added before the synthesis and the heat treatment was performed, it was confirmed that a material having a different crystal structure was synthesized even when a small amount of carbon material was added. In the case of $Li_4Ti_5O_{12}$ without the carbon material, the electrical conductivity value was about $10{\mu}S\;m^{-1}$, which was very small and similar to that of the nonconductor. As the carbon was added, the electrical conductivity was greatly improved and increased up to 10,000 times. Electrochemical impedance spectroscopy (EIS) analysis showed that the size of semicircle corresponding to the resistance decreased with the carbon addition. This indicates that the resistance inside the electrode is reduced. According to the Cyclic voltammetry (CV) analysis, the potential difference between the oxidation peak and the reduction peak was reduced with carbon addition. This means that the rate of lithium ion insertion and deinsertion was increased. $Li_4Ti_5O_{12}$ with 9.5 wt% PVC added sample showed the best properties in rate capabilities of $180mA\;h\;g^{-1}$ at 0.2 C-rate, $165mA\;h\;g^{-1}$ at 0.5 C-rate, and $95.8mA\;h\;g^{-1}$ at 5 C-rate.

• Journal of Animal Science and Technology
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• v.52 no.5
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• pp.413-426
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• 2010

This study was conducted to investigate the effects on fermentation characteristics of rumen microorganism by different types and levels of lignosulfonate treated soybean meal (LSBM) in in vitro test and rumen simulation continuous culture (RSCC) system in dairy cows. The experiment I was control and 12 treatments (each with 3 replications) in vitro test to demonstrate composition of different types of treatments with lignosulfonate (Desulfonate, Na, Ca and solution) and levels (2, 4 and 8%) of soybean meal in the dairy cow diet. LSBM source treatments in the dairy cow diet showed pH value, $NH_3$-N concentration and total VFA concentration lower than control at all levels and incubation times (p<0.05). Dry matter digestibility of LSBM source treatments showed lower than control (p<0.05). Gas production and rumen microbial synthesis was decreased by rumen microbial fermentation for incubation times. Undegradable protein (UDP) concentration of all LSBM treatments was decreased for incubation times, and significantly higher than control (p<0.05). In the experiment II compared diets of the control, LSBM Na 2%, LSBM Sol 2%, which are high performance to undegradable protein (UDP) concentration experiment I in vitro test, and heated treatment lignosulfonate (LSBM Heat) 2% in the dairy cow diet from four station RSCC system ($4{\times}4$ Latin square). A rumen microbial fermentation characteristic was stability during 12~15 days of experimental period in all treatments. The pH value of LSBM treatments was higher than control treatment (p<0.05). The $NH_3$-N concentration, VFA concentration and rumen microbial synthesis of LSBM treatments were lower than control (p<0.05). The undegradable protein (UDP) showed LSBM Na 2% (45.28%), LSBM Sol 2% (43.52%) and LSBM Heat 2% (43.49%) higher than control (41.55%), respectively (p<0.05). Those experiments were designed to improve by-pass protein of diet and milk protein in the dairy cows. We will conduct those experiments the in vivo test by LSBM treatments in dairy cows diet.