• Journal of the Korean Mathematical Society
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• v.56 no.4
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• pp.857-867
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• 2019

Suppose that G = (V, E) is a connected locally finite graph with the vertex set V and the edge set E. Let ${\Omega}{\subset}V$ be a bounded domain. Consider the following quasilinear elliptic equation on graph G $$\{-{\Delta}_{pu}={\lambda}K(x){\mid}u{\mid}^{p-2}u+f(x,u),\;x{\in}{\Omega}^{\circ},\\u=0,\;x{\in}{\partial}{\Omega},$$ where ${\Omega}^{\circ}$ and ${\partial}{\Omega}$ denote the interior and the boundary of ${\Omega}$, respectively, ${\Delta}_p$ is the discrete p-Laplacian, K(x) is a given function which may change sign, ${\lambda}$ is the eigenvalue parameter and f(x, u) has exponential growth. We prove the existence and monotonicity of the principal eigenvalue of the corresponding eigenvalue problem. Furthermore, we also obtain the existence of a positive solution by using variational methods.

• Journal of the Korean Chemical Society
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• v.17 no.1
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• pp.1-9
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• 1973

The purpose of this paper is to investigate the mechanism of Diels-Alder reaction by assuming pseudo molecular complex (PMC) which has characters both of ionic and radical bonds. We treated this complex quantum-chemically as an intermediate between the configuration without charge transfer (radical bond character) and the configuration corresponding to the charge transfer from Diene (R) to Dienophile (S) (ionic bond character). The wave function for the complex could be expressed as: ${\psi}_{complex} = {\psi}(R,S) +{ \rho}{\psi}(R^+,S^-)$ where ${\rho}$ is the extent of charge transfer which is a constant to measure the ionic character of PMC. It has been noticed that${\rho}$is related to the difference between Fr + Fr' and Fs + Fs' in free valence (F) when R is united to S through atom r in R to atom s in S and atom r' in R to atom s' in S, That is, ${\rho}{\alpha}$ ${\Delta}F = (Fr + Fr') - (Fs + Fs')$. We have calculated ${\Delta}F$values for more than forty Diels-Alder reactions. The calculated values of ${\Delta}F$ is reversely proportional to the values of Brown's paralocalization energy (Lp) as well as Dewar's differences of delocalization energy$({\Delta}Edeloc.)$ with good linearity. This approach also presents a way of predicting the possibility and the easiness of diene synthesis between any two conjugate compounds. According to the considerations, it could be concluded that Diels-Alder reaction takes place through the united ionic-radical mechanism rather than the separated ionic or radical mechanism.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.217-222
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• 1985

The yield responses of three isogenic lines in plant type of paddy rice(open-, spread- and broom-type) as affected by combined treatments of transplanting densities (47.62, 22.22, 15.15, 11.11 and 8.33 hills per sq. meter) and rates of fertilizer application (0, 0.5, 1.0 and 1.5 folds of standard rate) were studied by using of the partial differentiations by planting density(D):df(D,F)/dD, fertilizer rate(F):df(D,F)/dF, and their interaction(DXF):d$^2$ f(D,F)/dDdF from the multiple regression polynominal equations. Under the condition of wider planting, the broom-type showed most prominent and sensitive responses in yield among others. Also the action of transplanting density in the broom-type were positive both at lower and higher densities. Under the lower densities, the broom-type represented positive actions both at lower and higher rates of fertilizer application. Whereas the interactions between the density and fertilizer rate under the lower densities were rather negative. To achieve the labor-saving by lower transplanting density(11-14 hills per sq. meter), the amount of fertilizer rates were estimated as 1.3-1.5 folds much of the standard in the open-type, whereas more than 1.5 folds in the broom-type. Thus, the potentials to absorb more amounts of fertilizer may explain the compensating function of the broom-type for equivalent yields of the standards at reduced transplanting densities.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.661-670
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• 2017

50-year tree-ring ${\delta}^{18}O$ chronologies (1966~2015) for principle conifer tree species (Taxus cuspidata, Pinus koraiensis, Abies koreana) and Quercus mongolica at subalpine zone in Mt. Jiri were established. The establishing of tree-ring ${\delta}^{18}O$ chronologies for each tree species were fulfilled using four trees, which showed the good result in cross-dating. In the comparisons between tree-ring ${\delta}^{18}O$ chronologies within the same tree species all tree species showed reliable results statistically (p < 0.001), and they also showed EPS higher than 0.85. In addition to, the reliable correlations (p < 0.001) were verified between tree-ring ${\delta}^{18}O$ chronologies of four tree species, as well. In the response function analysis in order to investigate the relationships between tree-ring ${\delta}^{18}O$ chronologies and corresponding climatic factors, i.e., monthly precipitation and mean temperature, T. cuspidata showed a negative correlation with May precipitation (p < 0.05) and A. koreana showed a negative correlation with April precipitation (p < 0.05). If long tree-ring ${\delta}^{18}O$ chronologies of T. cuspidata and A. koreana will be established, it will be possible to reconstruct April and May precipitation in the past when we have no the meteorological data.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.1-1
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• 2016

Many of the world's large ecosystems are severely stressed due to population growth, water quality and quantity problems, vulnerability to flood and drought, and the loss of native species and cultural resources. Consequences of climate change further increase uncertainties about the future. These major societal challenges must be addressed through innovations in governance, policy, and ways of implementing management strategies. Science and engineering play a critical role in helping define possible alternative futures that could be achieved and the possible consequences to economic development, quality of life, and sustainability of ecosystem services. Science has advanced rapidly during the past decade with the emergence of science communities coalescing around 'Grand Challenges' and the maturation of how these communities function has resulted in large interdisciplinary research networks. An example is the River Experiment Center of KICT that engages researchers from throughout Korea and the world. This trend has been complemented by major advances in sensor technologies and data synthesis to accelerate knowledge discovery. These factors combine to allow scientific debate to occur in a more open and transparent manner. The availability of information and improved communication of scientific and engineering issues is raising the level of dialogue at the science-policy interface. However, severe challenges persist since scientific discovery does not occur on the same timeframe as management actions, policy decisions or at the pace sometimes expected by elected officials. Common challenges include the need to make decisions in the face of considerable uncertainty, ensuring research results are actionable and preventing science being used by special interests to delay or obsfucate decisions. These challenges are explored in the context of examples from the United States, including the California Bay-Delta system. California transfers water from the wetter northern part of the state to the drier southern part of the state through the Central Valley Project since 1940 and this was supplemented by the State Water Project in 1973. The scale of these activities is remarkable: approximately two thirds of the population of Californians rely on water from the Delta, these waters also irrigate up to 45% of the fruits & vegetables produced in the US, and about 80% of California's commercial fishery species live in or migrate through the Bay-Delta. This Delta region is a global hotspot for biodiversity that provides habitat for over 700 species, but is also a hotspot for the loss of biodiversity with more than 25 species currently listed by the Endangered Species Act. Understanding the decline of the fragile ecosystem of the Bay-Delta system and the potential consequences to economic growth if water transfers are reduced for the environment, the California State Legislature passed landmark legislation in 2009 (CA Water Code SS 85054) that established "Coequal goals of providing a more reliable water supply for California and protecting, restoring, and enhancing the Delta ecosystem". The legislation also stated that "The coequal goals shall be achieved in a manner that protects and enhances the unique cultural, recreational, natural resource, and agricultural values of the Delta as an evolving place." The challenges of integrating policy, management and scientific research will be described through this and other international examples.

• The Plant Pathology Journal
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• v.35 no.4
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• pp.351-361
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• 2019

In our previous study, pyrrolnitrin produced in Pseudomonas chlororaphis G05 plays more critical role in suppression of mycelial growth of some fungal pathogens that cause plant diseases in agriculture. Although some regulators for pyrrolnitrin biosynthesis were identified, the pyrrolnitrin regulation pathway was not fully constructed. During our screening novel regulator candidates, we obtained a white conjugant G05W02 while transposon mutagenesis was carried out between a fusion mutant $G05{\Delta}phz{\Delta}prn::lacZ$ and E. coli S17-1 (pUT/mini-Tn5Kan). By cloning and sequencing of the transposon-flanking DNA fragment, we found that a vfr gene in the conjugant G05W02 was disrupted with mini-Tn5Kan. In one other previous study on P. fluorescens, however, it was reported that the deletion of the vfr caused increased production of pyrrolnitrin and other antifungal metabolites. To confirm its regulatory function, we constructed the vfr-knockout mutant $G05{\Delta}vfr$ and $G05{\Delta}phz{\Delta}prn::lacZ{\Delta}vfr$. By quantifying ${\beta}-galactosidase$ activities, we found that deletion of the vfr decreased the prn operon expression dramatically. Meanwhile, by quantifying pyrrolnitrin production in the mutant $G05{\Delta}vfr$, we found that deficiency of the Vfr caused decreased pyrrolnitrin production. However, production of phenazine-1-carboxylic acid was same to that in the wild-type strain G05. Taken together, Vfr is required for pyrrolnitrin but not for phenazine-1-carboxylic acid biosynthesis in P. chlororaphis G05.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.6
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• pp.857-866
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• 2011

This study examined the metabolism of free radicals in hepatic mitochondria of goats induced by lipopolysaccharide (LPS), and investigated the effects of melatonin (MT). Forty-eight healthy goats ($10{\pm}1.2\;kg$) were randomly selected and divided into four groups: saline control, LPS, MT+LPS and MT. The goats within each group were3 sacrificed either 3 or 6 h after treatment and the livers removed to isolate mitochondria. The respiration control ratio (RCR), the ADP:O ratio, the oxidative phosphorylation ratio (OPR), the concentration of $H_2O_2$ and the activities of Complex I-IV were determined. The mitochondrial membrane potential ($\Delta\psi_m$) was analyzed by flow cytometry. The results showed that RCR, O/P and OPR of the LPS group decreased (p<0.05), as well as activities of respiratory complexes, whereas the generation of $H_2O_2$ in Complex III increased (p<0.05) after 3 h, while Complex II and III increased after 6 h. Also, it was found that the mitochondrial membrane potential of the LPS group declined (p<0.05). However, pre-treatment with MT attenuated the injury induced by LPS, which not only presented higher (p<0.05) RCR, O/P, OPR, and respiratory complex activities, but also maintained the $\Delta\psi_m$. Interestingly, it is revealed that, in the MT+LPS group, the generation of $H_2O_2$ increased firstly in 3 h, and then significantly (p<0.05).decreased after 6 h. In the MT group, the function of mitochondria, the transmenbrane potential and the generation of $H_2O_2$ were obviously improved compared to the control group. Conclusion: melatonin prevents damage caused by LPS on hepatic mitochondria of goats.

• Journal of Educational Research in Mathematics
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• v.27 no.4
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• pp.727-745
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• 2017

This study investigated the Aristotle's continuity and the historical development of continuity of function to explore the differences between the concepts of mathematics and students' thinking about continuity of functions. Aristotle, who sought the essence of continuity, characterized continuity as an 'indivisible unit as a whole.' Before the nineteenth century, mathematicians considered the continuity of functions based on space, and after the arithmetization of nineteenth century modern ${\epsilon}-{\delta}$ definition appeared. Some scholars thought the process was revolutionary. Students tended to think of the continuity of functions similar to that of Aristotle and mathematicians before the arithmetization, and it is inappropriate to regard students' conceptions simply as errors. This study on the continuity of functions examined that some conceptions which have been perceived as misconceptions of students could be viewed as paradigmatic thoughts rather than as errors.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.200-204
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• 2003

A statistical experiment method was employed to investigate the window of the thermal stability of $TiSi_2$films which are popular for Ti-salicide and ohmic layers. The statistical experimental results showed that the first order term of $TiSi_2$thickness and annealing temperature was acceptable as a function of $\Delta$resistivity by 95% reliability criteria, and R-sq value implying a fit accuracy of the model also showed a high value of 93.80%. We found that $\Delta$resistivity of the $TiSi_2$film annealed at $700^{\circ}C$ for 1 hr changed from 3.35 to $0.379\mu$$\Omega$$\cdot$cm with increasing thickness from 185 to $703\AA$, and TEX>$\Delta$resistivity of the $TiSi_2$film with a fixed thickness of 444 $\AA$ changed from 0.074 to 17.12 $\mu$$\Omega$$\cdot$cm with increasing temperature increase from 600 to $800^{\circ}C$. From these results, we report that the process conditions of$ 692^{\circ}C$-1 hr, $715^{\circ}C$-1 hr, and 73$0^{\circ}C$-1 hr for $TiSi_2$($400 \AA$) are stable by the criteria of 1, 2, and 3 $\mu$$\Omega$$\cdot$cm of $\Delta$resistivity, respectively.

• Membrane Journal
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• v.14 no.4
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• pp.304-311
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• 2004

The poly(1-trimethylsilyl-1-propyne) (PTMSP) and silica-filled PTMSP membranes were prepared by casting from a toluene solution on porous polyetherimide (PEI). FT-IR spectrum, GPC and SEM pictures have been taken to characterize the membranes. The particle size of membrane decreases as silica content of the membrane increases from 23 to 60 wt%, and a uniform distribution of the silica is observed. The separation properties of the gas mixture (32 mol% $H_2$/ 68 mol% $N_2$) through the composite membranes were studies as a function of pressure and percentage of silica. Selectivity values of $H_2$/$N_2$ increased as the pressure of permeation cell and silica content of the membrane increased. The real separation factor($\alpha$), head separation factor($\beta$), and tail separation factor((equation omitted)) of PTMSP-PEI composite membrane were 2.28, 1.58, and 1.44 respectively at $\Delta$P 30 psi and $25^{\circ}C$. $\alpha$, $\beta$, and (equation omitted) of PTMSP-Silica-PEI composite membrane for 60 wt% silica were 3.34, 1.95, 1.72 at $\Delta$P 30 psi and $25^{\circ}C$.