• Korean Journal of Materials Research
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• v.12 no.1
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• pp.68-74
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• 2002

The lead has to be removed for the recycling of copper alloy. The lead cannot be removed from the copper alloy by oxidation. It can be removed by the evaporation because of its high vapor pressure. However, rare information is found on removal of lead from copper alloy. The purpose of present work is to provide a fundamental knowledges on the removal of lead from the copper alloy by evaporation. Gas injection was made in molten copper alloy, and the evaporation rate of lead was measured. The influence of Ar gas flow rata(2~4 L/min), initial contents of lead(2~4wt%Pb), temperature(1200~140$0^{\circ}C$) was investigated based on the thermodynamic and the kinetics. The rate constant is increased with increasing flow rate of Ar and temperature. Though amount of lead removed is increased with higher initial lead concentration, the rate constant is not changed significantly. The activation energy is estimated from the temperature dependence of the rate constant. Also removal of lead from the copper by adding chloride was made for the comparison.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.238-238
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• 2009

In this work, we investigated the effect of the Zn complex concentration and growth temperature on the growth of ZnO nanorod by hydrothermal method. The ZnO nanorods were performed at condition of the various Zn complex concentration and growth temperature, 0.02 ~ 0.08 M and 60 ~ 80 $^{\circ}C$, respectably. We found from the SEM results that the diameter and length of ZnO nanorods were with increasing the growth temperature and Zn complex concentration. However, the growth condition in the two parameters wasmore than sensitive compared to Zn complex concentration on increasing the growth rate. From photoluminescence(PL) analysis, the strong band-edge emission for ZnO nanorod grown at 80 $^{\circ}C$ with 0.08 M indicated the fine crystallinity. Therefore, the diameter and length of ZnO nanorods have been able to control through the control of front growth parameters. Also, these ZnO nanorods grown low temperature will be available as building block for transparence flexible device applications.

• Journal of the Korean institute of surface engineering
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• v.9 no.2
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• pp.1-7
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• 1976

The dissolving and growth kinetics of intermetallic compounds for the reaction between solid iron and molten zinc were studied under nitorgen atmosphere over the temperature range between470$^{\circ}C$ and 680$^{\circ}C$. The rates of dissolution of solid iron into molten zinc were obtained under a static conditon, The amount of dissolution of sold iron and the growth of intermetalic compounds could be determined by means of microscopy. The thickness of intermetallic compound at a given temperature increases with increasing time, whereas for a given time decreases with increasing temperature . The rate of dissolution is controlled by the diffusion process of iron in the effective boundary layer of molten zinc over the temperature range 470$^{\circ}$-530$^{\circ}C$, 570$^{\circ}$-620$^{\circ}C$, and 650$^{\circ}$-665$^{\circ}C$, while by the surface reaction over the range 530$^{\circ}$-570$^{\circ}C$ and 620$^{\circ}$-650$^{\circ}C$.

• Transactions of Materials Processing
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• v.16 no.3 s.93
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• pp.193-200
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• 2007

Simulations of the thermally-induced residual stresses and birefringence in freely quenched plates of polycarbonate were performed by using the linear viscoelastic and photoviscoelastic constitutive equations for the mechanical and optical properties, respectively, and the first order rate equation for volume relaxation. The predictions for the birefringence showed good agreement with experimental measurements. However, for initial temperature close to the glass transition temperature, some differences existed around the surface layer. Based on the simulation, the influences of various cooling conditions on the residual stress and birefringence in plates were investigated. The residual stress and birefringence increased with increasing initial temperature, decreasing coolant temperature and increasing heat transfer coefficient of coolants.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.379-380
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• 2002

Steam generators (S/G) of pressurized water reactors are large heat exchangers that use the heat from the primary reactor coolant to make steam in the secondary side for driving turbine generators. Reciprocating sliding wear experiments have been performed to examine the wear properties of Incoloy 800 and Inconel 690 steam generator tubes in high temperature water. In present study, the test rig was designed to examine the reciprocating and rolling wear properties in high temperature (room temperature - $300^{\circ}C$) water. The test was performed at constant applied load and sliding distance to investigate the effect of test temperature on wear properties of steam generator tube materials. To investigate the wear mechanism of material, the worn surfaces were observed using scanning electron microscopy. At $290^{\circ}C$, wear rate of Inconel 690 was higher than that of Incoloy 800. It was assumed to be resulted from the oxide layer property difference due to the a\loy composition difference. Between 25 and $150^{\circ}C$ the wear loss increased with increasing temperature. Beyond $150^{\circ}C$, the wear loss decreased with increasing temperature. The wear loss change with temperature were due to the formation of wear protective oxide layer. From the worn surface observation, texture patterns and wear particle layers were found. As test temperature increased, the proportion of particle layer increased.

• Journal of the Korean Ceramic Society
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• v.35 no.7
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• pp.749-756
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• 1998

TiC-Ni and TiC-Ni-Mo cermet powders were produced by Self-propagating High temperature Synthesis (SHS) process. The cooling rate of synthesized powders were controlled by using the V-shaped copper jig and the carbide size decreased with increasing the cooling rate I. e decreasing the width of copper jig Round shape carbide particles were produced after SHS reaction in TiC-Ni as well as TiC-Ni-Mo powders. Local segregation of Mo rich phases was observed in SHS powder of TiC-Ni-Mo and the uneven dis-triobution of Mo promoted the faster growth rate of carbide particles during sintering compared to the same composition specimen with commercial TiC powder. Howogeneous microstructure of TiC-Ni-Mo cermet was obtained when the elemental Mo powder was mixed with the SHS powder of TiC-Ni.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.346-348
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• 2002

This study estimated the effect of influent TAN concentration. temperature and pH in the airlift bioreactor(aeration rate; 1.5 vvm, HRT 0.35hr) using immobilized nitrifiers by PVA. At the effect of influent TAN concentration, removal rate was increased with increasing it and removal efficiency maintained 93${\pm}$2%. The optimum temperature for nitrification was $30^{\circ}C$ and at this point. removal efficiency was 95.5${\pm}$1.5%. It was effective to nitrify at $10^{\circ}C$ of low temperature. In the pH range from 7 to 9 in the bioreactor. removal rate and removal efficiency was 310${\pm}$10 $g/m^3$ day and 94${\pm}$3%.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.185-188
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• 1997

Static restoration during hot interrupted deformation of 304 stainless steel was studied in the temperature range from 900 to 1100$^{\circ}C$ under various strain rate of 0.05∼ 5/sec and pass strain of 1/4∼3 times peak strain. The static restoration was dependent on the pass strain, deformation temperature and strain rate. Fractional softening(FS) values increased with increasing strain rate, deformation temperature and pass strain. Recystallization kinetics was well explained by the Avrami equation and the time for 50% recrystallization was evaluated using equation of t0.5=2.01${\times}$10-10$\varepsilon$-.156$\varepsilon$ -0.81Dexp(196.66/RT)

• Journal of the Korean Chemical Society
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• v.65 no.3
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• pp.185-196
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• 2021

For studying the reaction mechanism of the reactions related to NO in the ozone denitration reactions, the harmonic and anharmonic rate constants were calculated by the transition state (TS) theory and Yao and Lin (YL) method. According to above calculations, the reactions of NO with O₃ and NO₃ play an essential role, and the kinetic parameters considering anharmonic effect were fitted. Furthermore, the rate constants were up as temperature increasing, and the tendencies of high temperature were more gradual than the low temperature. The research will provide theoretical basis for the ozone denitration reactions.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.1
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• pp.75-84
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• 2015

This study was conducted to investigate the effects of high temperature and drought on growth performance, photosynthetic parameters and photosynthetic pigment contents of Liriodendron tulipifera L. seedlings. The seedlings were grown in controlled-environment growth chambers with combinations of four temperature ($-3^{\circ}C$, $0^{\circ}C$, $+3^{\circ}C$, $+6^{\circ}C$; based on the monthly average for 30 years in Korea) and two water status (control, drought). Temperature rise increased growth, total dry weight and leaf area in all water status. Also photosynthetic rate, dark respiration, stomatal conductance and transpiration rate increased with increasing temperature. In contrast, growth and photosynthetic parameters of L. tulipifera seedlings were lower in $-3^{\circ}C$ than $0^{\circ}C$. But temperature rise decreased water use efficiency in all water status. Temperature rise increased photosynthetic pigment contents of leaf. Also chlorophyll a/b ratio increased with increasing temperature. In conclusion, the elevated temperature lead to causes growth increase through the increase of energy production by higher photosynthetic rate during a growth period of L. tulipifera seedlings.