• Journal of Aquaculture
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• v.10 no.2
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• pp.123-131
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• 1997

Growth of triploid abalone, Haliotis discus hannai induced by cody (3$^{\circ}C$) shock and its feed efficiency were investigated from larva to adult for 51 months. After 51 months from triploidy induction, the triploid abalones have outgrown to diploid abalones in shell length and total weight. Triploid abalones with inhibition of extrusion of first polar body (3n-1pb) were outgrown to diploid abalones, however, triploid abalones with inhibition of extrusion of second polar body (3n-2pb) were not significantly different from diploid controls in shell length and total weight through the whole rearing period (P<0.05), because of their heterozygosity differences. Daily feeding rates and feed conversion rates decreased with the growth of abalones and both rates had no differnce between two experimental groups. After 51 months from inducing triploid, conditin index of triploid abalone (64.1%) was higher than that of diploid control (59.4%) (P<0.05). Survival rate was 63.0% in triploid group (3n-1pb 62.0%, 3n-2pb 64.0%) and 62.0% in diploid group during the experimental period.

• Journal of the Korean Applied Science and Technology
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• v.23 no.4
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• pp.347-354
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• 2006

Generally, it has been known that positive plate efficiency is the most influential effect on the initial current capacity of lead acid battery. Thus, in this study, we have investigated the curing effect of the positive plate, which is one of the important lead acid battery processes. The curing process of the positive plate is performed either with the separation of each plate with 1mm gap or with no gap of plate. As a result, when there is no interval between each plate, the higher temperature current happened than expected, resulting in the changes in the initial current efficiency of the lead acid battery. The chemical composition and crystal structure of a material coated on the positive plate were identified with XRD and SEM. It was resulted that were only there not a lot of 4BS (tetrabasic-lead sulfate, $4PbO{\cdot}PbSO_4)$ on the plate in case of curing of plates without interval, but a large quantity of $Pb_3O_4$ also formed on the surface. On the other hand, it was observed that 3BS (tribasic-lead sulface, $3PbO{\cdot}PbSO_4{\cdot}H_2O)$ was the main product on the plate in case of typical curing process with some interval. From the initial current capacity test, the positive plate having 3BS was approximately 40% higher in initial current capacity than that having 4BS. It was concluded that 4BS and $Pb_3O_4$ on the plate surface were harmful to the initial current capacity of lead acid battery.

• Journal of Welding and Joining
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• v.20 no.4
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• pp.505-509
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• 2002

Pb is considered to be eliminated from solder, due to its toxicity. However, melting temperatures of most Pb-free solders are known higher than that of Sn37Pb. Therefore, there is a difficulty to apply Pb-free solders to electronic industry. Since Sn3Ag8Bi5In has relatively lower melting range as $188~200^{\circ}C$, on this study. Wettability and soldering characteristics of Sn3Ag8Bi5In solder in BGA were investigated to solve for what kind of problem. Zero cross time, wetting time, and equilibrium force of Sn3Ag8Bi5In solder for Cu and plated Cu such as Sn, Ni, and Au/Ni-plated on Cu were estimated. Plated Sn on Cu showed best wettability for zero cross time, wetting time and equilibrium farce. Shear strength of the reflowed joint with Sn3Ag8Bi5In ball in BGA was investigated. Diameter of the ball was 0.5mm, UBM(under bump metallurgy) was $Au(0.5\mu\textrm{m})Ni(5\mu\textrm{m})/Cu(18\mu\textrm{m})$ and flux was RMA type. For the reflow soldering, the peak reflow temperature was changed in the range of $220~250^{\circ}C$, and conveyor speed was 0.6m/min.. The shear strength of Sn3Ag8Bi5In ball showed similar level as those of Sn37Pb. The soldered balls are aged at $110^{\circ}C$ for 36days and their shear strengths were evaluated. The shear strength of Sn3Ag8Bi5In ball was increased from 480gf to 580gf by aging for 5 days.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.471-478
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• 2011

Investigations of crystal structure and phase transition of $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics doped with A-site substitution impurity (La, Nd) or B-site substitution impurity (Sb, Nb) at 2 mol% concentration were carried out. X-ray diffraction patterns of impurities doped $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics have been measured at pressures up to ~5 GPa with diamond anvil cell and synchrotron radiation. The patterns were obtained at room temperature using methanol-ethanol mixture as pressure-transmitting media. In order to refine the crystal structure, Rietveld analysis has been performed. The structures of impurities doped $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics are tetragonal in space group P4mm at ambient pressure and are transformed into a cubic phase in space group Pm$\bar{3}$m as the pressure increases. In this study, when A-site substitution donor $La^{3+}$ or $Nd^{3+}$ ion was added to $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics, the phase transition phenomena showed up at the pressure of 2.5~4.6 GPa, but when B-site substitution donor $Nb^{5+}$ or $Sb^{5+}$ ion was added to it, the phase transition appeared at relatively lower pressure of 1.7~2.6 GPa.

• Economic and Environmental Geology
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• v.42 no.2
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• pp.121-131
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• 2009

The distribution characteristics of heavy metals for surface sediments in east oceanic dumping area (EDA) and west oceanic dumping area (WDA) are evaluated by grain sizes, minerals, sedimentation rates and compositions of heavy metals. The mean grain sizes in EDA and WDA range from $7.95{\Phi}$ to $8.51{\Phi}$ and $7.42{\Phi}$ to $8.15{\Phi}$, respectively. These are mostly belonging to the M (mud) type. Minerals in the surface sediments consist of illite with chlorite, smectite, and kaolinite. Sedimentation rates estimated by $^{210}Pb$ method in EDA and WDA are 1.11 mm/yr$\sim$1.73 mm/yr and 1.87 mm/yr, respectively. According to the interrelationship, concentrations of Ni, Cu, Cr, and Zn are closely associated with mean grain size, Al, and Fe, whereas concentrations of Cd and Pb are poorly associated with ones. The enrichment factors of these elements are higher than 1.5, suggesting that the concentrations of Cd and Pb in the surface sediments are affected by anthropogenic sources. The $I_{geo}$-class numbers of Cd and Pb in the surface sediments are mostly classified in 2 to 4, showing moderate to strongly polluted. These numbers in EDA are higher than that of WDA, and the highest number is 4, indicative of the strongly polluted class. Our results show that the disposed wastes at EDA include mineralogical wastes, dredged materials from sewage disposals, and sludges from constructions having materials of WDA. The annual amount of oceanic dumping in EDA is double than that in WDA.

• Journal of the Korean Wood Science and Technology
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• v.41 no.1
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• pp.33-41
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• 2013

This study was performed to analyse cause of quality deterioration using byproduct of plywood and to determine physical and mechanical properties of particleboard used new bonding condition we found. The result of bending strength of Com-Ply board using EMDI is 57.7 $N/mm^2$ on linear direction and 25.1 $N/mm^2$ on vertical direction. EMDI has better water-resisting qualities than Urea formaldehyde adhesive according to result of thickness swelling and water absorption test. Pre-treatment soaked particle 72 hours in water caused increase of HCHO emission.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.129-135
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• 2013

Recently, waste water treatment system is developed in small and middle size to get more economic advantage. Freeze concentration system has high thermodynamic efficiency and low energy consumption, can re-use purified water and cold energy obtained from ice. This study was experimentally performed to investigate pollution containment in frozen layer by cooling wall temperature, air-bubble flow methods, initial ice-lining thickness of frozen layer in NaCl aqueous solution and the representative heavy metals, Pb and Cr aqueous solution. As the result, a decrease in the cooling wall temperature bring a higher growth rate of ice front and the more solute was involved in frozen layer. The method to inject directly air-bubble into ice-liquid interface through ring shape nozzle gave high purity of ice compared to indirect method. Ice lining in 5mm thickness resulted in frozen layer with higher purity than 1mm thickness.

• Proceedings of the Korean Magnestics Society Conference
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• 2015.11a
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• pp.58-58
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• 2015

• Journal of Welding and Joining
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• v.20 no.6
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• pp.59-59
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• 2002

Sn-Ag-Cu solder is known as most competitive in many kinds of Pb-free solders. In this study, effects of solderability with plated layers such as Cu, Cu/Sn, Cu/Ni and Cu/Ni/Au were investigated. Sn-3.5Ag-0.7Cu solder balls were reflowed in commercial reflow machine (peak temp. : 250℃ and conveyer speed : 0.6m/min). In wetting test, immersion speed was 5mm/sec., immersion time 5sec., immersion depth 4mm and temperature of solder bath was 250℃. Wettability of Sn-3.5Ag-0.7Cu on Cu, Cu/Sn (5㎛), Cu/Ni (5㎛), and Cu/Ni/Au (5㎛/500Å) layers was investigated. Cu/Ni/Au layer had the best wettability as zero cross time and equilibrium force, and the measured values were 0.93 sec and 7mN, respectively. Surface tension of Sn-3.5Ag-0.7Cu solder turmed out to be 0.52N/m. The thickness of IMC is reduced in the order of Cu, Cu/Sn, Cu/Mi and Cu/Ni/Au coated layer. Shear strength of Cu/Ni, Cu/Sn and Cu was around 560gf but Cu/Ni/Au was 370gf.

• Journal of Welding and Joining
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• v.20 no.6
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• pp.783-788
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• 2002

Sn-Ag-Cu solder is known as most competitive in many kinds of Pb-free solders. In this study, effects of solderability with plated layers such as Cu, Cu/Sn, Cu/Ni and Cu/Ni/Au were investigated. Sn-3.5Ag-0.7Cu solder balls were reflowed in commercial reflow machine (peak temp.:$250^{\circ}C$and conveyer speed:0.6m/min). In wetting test, immersion speed was 5mm/sec., immersion time 5sec., immersion depth 4mm and temperature of solder bath was $250^{\circ}C$. Wettability of Sn-3.5Ag-0.7Cu on Cu, Cu/Sn ($5\mu\textrm{m}$), Cu/Ni ($5\mu\textrm{m}$), and Cu/Ni/Au ($5\mu\textrm{m}/500{\AA}$) layers was investigated. Cu/Ni/Au layer had the best wettability as zero cross time and equilibrium force, and the measured values were 0.93 sec and 7mN, respectively. Surface tension of Sn-3.5Ag-0.7Cu solder turmed out to be 0.52N/m. The thickness of IMC is reduced in the order of Cu, Cu/Sn, Cu/Mi and Cu/Ni/Au coated layer. Shear strength of Cu/Ni, Cu/Sn and Cu was around 560gf but Cu/Ni/Au was 370gf.