• Journal of Welding and Joining
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• v.11 no.4
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• pp.91-102
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• 1993

The plasma sprayed $Cr_3C_2$-NiCr coatings are widely used as wear-resistant and corrosion-resistant materials. The mechanical and wear properties of the plasma sprayed $Cr_3C_2$-NiCr coating on steel plate were examined in this study. The pore in the coatings could be classified into two types, the one is the intrinsic pore originated from the spraying powder, the other is the extrinsic pore formed during spraying. During the tensile adhesion test, the fracture occured at the interface of top coating and bond coating. It is though that the compressive residual stress increases with the increase of the top coating thickness. From the wear test, it was found that the wear rate increased with the increase of the sliding velocity regardless of the temperature. It is thought that the fracture toughness reduces with the increase of the sliding velocity at $30^{\circ}C$ and that the adhesion amount increases with the increase of the sliding velocity at $400^{\circ}C$ It is concluded that the wear mechanism at $30^{\circ}C$ is the fracture and pull-out of the carbide particles due to the fatigue on sliding surface, while the wear mechanism at $400^{\circ}C$ is the adhesion of the smeared layer formed during wear process.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.510-514
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• 1991

Second-order rate constants have been determined spectrophotometrically for reactions of S-p-nitrophenyl substituted thiobenzoates with various phenoxide ions and S-aryl substituted thiobenzoates with $HO^-$ ion. Thiol esters have been found to be more reactive than the corresponding oxygen esters toward phenoxide ions. The high reactivity of thiol esters relative to oxygen esters becomes insignificant as the basicity of the nucleophile increases. Furthermore, the highly basic $HO^-$ ion is less reactive toward thiol esters than oxygen esters. The significant dependence of the reactivity of thiol esters on the basicity of nucleophiles has been attributed to the nature of the HSAB principle. The present kinetic study has also revealed that the reactivity of thiol esters compared to oxygen esters is not so pronounced as expected based on the enhanced nucleofugicity of thiol esters. However, the effects of substituents in the nucleophile and in the acyl moiety of the substrate on rate appear to be significant. These kinetic results have led to a conclusion that the present reactions proceed via a rate-determining formation of a tetrahedral intermediate followed by a fast breakdown of it. The magnitude of the ${\beta}$ values shows no tendency either to increase or to decrease with the intrinsic reactivity of the reagents. The constancy of ${\beta}$ values in the present system is suggestive that the RSP should have limited applicability.

• Korean journal of applied entomology
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• v.40 no.3
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• pp.203-209
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• 2001

Development and reproduction of the sweetpotato whitefly, Bemisia tabaci(B biotype) were investigated under different temperatures and host plants. Developmental periods from egg to pre-adult of whiteflies measured under four constant temperatures: they were 86.2 days at $15^{\circ}C$ and 17.0 days at $30^{\circ}C$. Lower threshold temperature and total effective temperature for the development of egg and nymph, and for the complete development (egg to emergence) were $10.1,\;11.6,\;11.1^{\circ}C$ and 110.3, 204.7, 317.3 degree days, respectively. The hatching and emergence rates were 87.0% at $25^{\circ}C$ and 76.7% at $20^{\circ}C$, which were higher than the results of other temperatures. The adult longevity was 23.6 and 14.0 days at $20^{\circ}C$ and $30^{\circ}C$, respectively. The highest average fecundity per female was 103.3 at $25^{\circ}C$. But there were no significant differences among the temperatures. The highest intrinsic rate of natural increase($r_{m}$) was 0.196 at $30^{\circ}C$ and the highest net reproduction rate ($R_{o}$) was 97.33 at $25^{\circ}C$. Developmental periods from egg to pre-adult of whiteflies were 21.2 on the tomato, 28.1 on red pepper, 22.2 on eggplant and 25.5 days on poinsetia. The hatching was highest (90.3%) on red paper and emergence rate was highest (89.6%) on eggplant. The longest longevity of adult female was 26.5 days on eggplant, and the average fecundity per female was greater on tomato and eggplant than on other host plants. The intrinsic rate of natural increase($r_{m}$) was the highest on tomato as 0.165 and the net reproduction rate ($R_{o}$) was the highest on eggplant as 106.1. As a result, the optimum range of temperature for the growth of B. tabaci was between $25^{\circ}C$ and $30^{\circ}C$, and the optimum host plant were tomato and eggplant among the plants tested.

• Korean journal of applied entomology
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• v.41 no.2
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• pp.123-128
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• 2002

This study was carried out to test the effects of temperatures between 2$0^{\circ}C$ and 3$0^{\circ}C$ on the reproduction and development of the rice water weevil, Lissorhoptrus oryzophilus. Preoviposition periods were much longer (17.2 to 51.0 days) in the overwintering adult females collected in March than those collected in May, regardless of temperature. Oviposition periods, however, were longer (16.9 to 22.0 days) in the adult females collected in May than those collected in March at the same temperatures. The longer oviposition period observed in the females collected in May were directly associated with higher fecundity. Egg periods were shortened from as temperature increased, but the hatching rate was highest (100%) at 27$^{\circ}C$. The developmental periods from egg to adult were shortened as temperature increased : from 77.9 days at 2$0^{\circ}C$ to 38.3 days at 3$0^{\circ}C$. The developmental zero point temperature (T) and the total effect temperature (K) for egg were 16.3$^{\circ}C$ and 62.1 dgree days, respectively. The T and K from egg to adult emergence were 13.9$^{\circ}C$ and 577.6 dgree days, respectively. The adult females of the first generation did not oviposit at 2$0^{\circ}C$, but did at $25^{\circ}C$ and 3$0^{\circ}C$. The intrinsic rate of natural increase (r$_{m}$) increased as temperature augmented. Net reproductive rate (Ro) per generation was highest (75.3) at $25^{\circ}C$.>.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.296-301
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• 2005

The effect of aqueous methanol on the catalytic properties of porcine pancreatic lipase has been investigated. The k$_{CAT}$, values for the hydrolysis of N$^{alpha}$-benzyloxycarbonyl-L­lysine p-nitrophenyl ester at 0$^{circ}$C increased in a linear manner with increasing methanol concentration. However, the K$_{M}$ values were not influenced at methanol concentrations lower than $30\%$ and then began to increase at higher concentrations in an exponential fashion. Based on product analysis, the increase in k$_{CAT}$, with increasing methanol concentration can be accounted for by nucleophilic competition of methanol for the acyl enzyme intermediate, indicating that the rate-limiting step of the porcine pancreatic lipase-catalyzed reaction is deacylation under current experimental conditions. The exponential increase in K$_{M}$ at methanol concentrations higher than $30\%$ is attributed to the hydrophobic partitioning effect on substrate binding. There was no loss of lipase activity over a 4 h period in $60\%$ methanol concentration at pH$^{circ}$ 5.5 and 0$^{circ}$C. By monitoring the intrinsic fluorescence and absorbance, no evidence for structural changes by methanol was observed.

• Korean journal of applied entomology
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• v.61 no.4
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• pp.549-554
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• 2022

Life table-related studies in insect ecology have been an interesting topic for insect researchers. Two calculation methods are commonly applied to estimate the intrinsic rate of natural increase (r_m) in the life table statistics. The first method is to estimate an approximate r_m by dividing the natural logarithm of the net reproductive rate (R₀) by mean generation time (T) (namely mean generation time-based method). Another approach is to apply the Lotka-Euler equation derived from the population growth equation of Lotka-Volterra to estimate accurate r_m using the maximum likelihood method (Lotka-Euler equation-based method). In the latter case, there is a difference in the estimated r_m value when the initial age class of the target cohort was set to "0" or "1", which confused the application. In this short review, a brief history of the calculation process of the life table was reviewed. It was again confirmed in the Lotka-Euler equation-based method that the form of $\sum\limits_{x=1}^{w}e^{-rx}l_xm_x=1$ should be applied to estimate r_m when the first age class was set to zero, while the form of $\sum\limits_{x=0}^{w}e^{-r(x+1)}l_xm_x=1$ when set to one.

• Korean journal of applied entomology
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• v.38 no.2
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• pp.117-121
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• 1999

Development and reproduction of the sycamore lace bug, Corythucha ciliata, were investigated under different temperature regimes. Duration of development from egg to pre-adult of the sycamore lace bug measured seven temperatures ranged from 54.0 days at 18$^{\circ}$C to 17.9 days at 33$^{\circ}$C. Development was not successful at 15$^{\circ}$C and 35$^{\circ}$C. Developmental zero point and total effective temperature for development of egg, nymphal, and complete development were 1 1 .O, 10.9, ll.l$^{\circ}$C and 150.3, 230.6, 376.1 degree-days, respectively. Longevities of adult females varied to temperature from 51.8 days at 18$^{\circ}$C to 17.2 days at 33$^{\circ}$C. The average fecundity per female was greater at 25$^{\circ}$C and 28$^{\circ}$C compared with at other temperatures. The intrinsic rate of natural increase (r,) and net reproduction rate (R,) were highest at 28$^{\circ}$C as 0.170 and 73.25, respectively. As a result, optimum ranges of temperature for C. ciliata growth were between 25$^{\circ}$C and 28$^{\circ}$C.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.211-216
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• 2003

Development and reproduction of Dichromothrips smithi were investigated under different temperatures, Durations of the development from egg to pre-adult of D. smithi were measured under 11 temperature ranges and it was 44.0 days at 13$^{\circ}C$ and 8.7 days at 32$^{\circ}C$. Developmental zero point and total effective temperature for the development of egg and larva, prepupa, pupa and for the complete development (egg to emergence) were 9.4, 8.9, 10.5, 10.8 and 9.5$^{\circ}C$, and 46.1, 90.1, 23.9, 41.2 and 204.4 degree days, respectively. The adult longevity was 28.3 days at 15 C and 14.3 days at 30$^{\circ}C$. The highest average fecundity per female was 69.3 at 25 C. The highest intrinsic rate of natural increase (r$\_$m/) and the highest net reproduction rate (R$\_$o/) were 0.241 at 30$^{\circ}C$ and 56.56 at 25$^{\circ}C$. The optimum temperature range for the growth of D. smithi was between 25$^{\circ}C$ and 30$^{\circ}C$.

• Korean journal of applied entomology
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• v.41 no.3
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• pp.205-209
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• 2002

Effects of temperature on the development and reproduction of the Udea ferrugalis Hubner were investigated at various temperatures (10, 15, 18, 20, 23, 25, 27, 30$\^{C}$). The development times of eggs, larvae, prepupae and pupae were shorter in higher temperatures than in lower ones. Egg and pupa did not develop at 10$\^{C}$. The lower developmental threshold temperatures for eggs, larvae, pupae were 9.5, 9.6 and 11.9$\^{C}$, respectively, and their thermal requirements for development completion were 87.9, 200.9 and 119.7 degree-days at the same temperature, respectively. Adult longevity was 25.2 days at 15$\^{C}$, 7.3 at 23$\^{C}$ and 5.3 at 30$\^{C}$. Mean fecundity per female was higher at 20-23$\^{C}$ compared to other temperatures. Mean generation time in days (T) was shorter in higher temperature region. Net reproductive rate per generation (Ro) was lowest at 15$\^{C}$ (138.2) and it was highest at 20$\^{C}$ (265.4). The intrinsic rate of natural increase (r$\_$m/) was highest at 25$\^{C}$ as 0.247. As a result, it was considered that optimum range of temperature for U. ferrugalis growth was 20.0 to 23$\^{C}$.

• Korean journal of applied entomology
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• v.40 no.4
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• pp.297-300
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• 2001

Development and reproduction of the persimmon fruit moth, Stathmopoda masinissa, were investigated under different temperatures (15, 20, 25, and 3$0^{\circ}C$). It took 96.1 days to grow from egg to adult at 2$0^{\circ}C$, 43.2 days at $25^{\circ}C$, and 34.6 days at 3$0^{\circ}C$. At 15$^{\circ}C$, all tested individuals died before pupation. The developmental threshold temperatures for egg, larva, pupa, and adult were 12.2, 13.5, 13.8, and 13.4$^{\circ}C$, respectively. The total effective temperatures for egg, larva, pupa, and egg to adult were 74.0, 331.3, 160.5, and 569.9 degree days, respectively. The hatching, pupation, and emergence rates were highest at $25^{\circ}C$. The average life span of adult prior to laying eggs and the total life span of adult were 12.6 and 29.3 days at 2$0^{\circ}C$, 3.8 and 8.6 days at $25^{\circ}C$, and 2.5 and 7.0 days at 3$0^{\circ}C$, respectively. Mean generation time in days (T) was shorter at higher temperature. Net reproductive rate per generation (R$_{o}$) was lowest at 2$0^{\circ}C$. The intrinsic rate of natural increase (r$_{m}$) was highest at $25^{\circ}C$ as 0.066.