• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.279-292
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• 2011

In this paper, we consider anti-periodic solutions of the following BAM neural networks with multiple delays on time scales: $$\{{x^\Delta_i(t)=-a_i(t)e_i(x_i(t))+{\sum\limits^m_{j=1}}c_{ji}(t)f_j(y_j(t-{\tau}_{ji}))+I_i(t),\atop y^\Delta_j(t)=-b_j(t)h_j(y_j(t))+{\sum\limits^n_{i=1}}d_{ij}(t)g_i(x_i(t-{\delta}_{ij}))+J_j(t),}\$$ where i = 1, 2, ..., n,j = 1, 2, ..., m. Using some analysis skills and Lyapunov method, some sufficient conditions on the existence and exponential stability of the anti-periodic solution to the above system are established.

• Communications of the Korean Mathematical Society
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• v.35 no.4
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• pp.1269-1281
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• 2020

In this article, we show that a pseudo-Hermitian magnetic curve in a normal almost contact metric 3-manifold equipped with the canonical affine connection ${\hat{\nabla}}^t$ is a slant helix with pseudo-Hermitian curvature ${\hat{\kappa}}={\mid}q{\mid}\;sin\;{\theta}$ and pseudo-Hermitian torsion ${\hat{\tau}}=q\;cos\;{\theta}$. Moreover, we prove that every pseudo-Hermitian magnetic curve in normal almost contact metric 3-manifolds except quasi-Sasakian 3-manifolds is a slant helix as a Riemannian geometric sense. On the other hand we will show that a pseudo-Hermitian magnetic curve γ in a quasi-Sasakian 3-manifold M is a slant curve with curvature κ = |(t - α) cos θ + q| sin θ and torsion τ = α + {(t - α) cos θ + q} cos θ. These curves are not helices, in general. Note that if the ambient space M is an α-Sasakian 3-manifold, then γ is a slant helix.

• Kyungpook Mathematical Journal
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• v.46 no.1
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• pp.49-56
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• 2006

The aim of the present work is to obtain the inverse Laplace transform of the product of the factors of the type $s^{-\rho}\prod\limit_{i=1}^{\tau}(s^{li}+{\alpha}_i)^{-{\sigma}i}$, a general class of polynomials an the multivariable H-function. The polynomials and the functions involved in our main formula as well as their arguments are quite general in nature. On account of the general nature of our main findings, the inverse Laplace transform of the product of a large variety of polynomials and numerous simple special functions involving one or more variables can be obtained as simple special cases of our main result. We give here exact references to the results of seven research papers that follow as simple special cases of our main result.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1243-1245
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• 2003

Mean radiative forcing efficiencies (${\Delta}$F/${\Delta}{\tau}_{0.5}$) over East Asia range from -65 to -95 W m$^{-2}$ at the surface while -20 to -40 W m$^{-2}$ at TOA under clear-sky conditions. These aerosol direct radiative forcings over East Asia are similar to other experimental results for different regions, i.e., the Indian Ocean Experiment (INDOEX) and the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX), from which radiative forcing efficiencies of -75 Wm$^{-2}$ and -70 Wm$^{-2}$ for the Indian Ocean and the East Coast of the United States are reported. Nevertheless, the differences in aerosol parameters and relatively large STD values with regard to spatiotemporal variations suggest that the impact of aerosol on ARF over East Asia is more significant than previously recognized for other regions and should be continuously observed to determine the relation between increasing aerosols and associated radiative forcings in the region.

• Bulletin of the Korean Chemical Society
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• v.9 no.4
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• pp.202-206
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• 1988

In order to investigate the oligomerization state of the plasma membrane proteolipid apoprotein purified from the bovine kidney, fluorescence polarization experiment was carried out in the two different solvent systems, i.e., water and organic solvent(chloroform-methanol). The molecular volumes of the proteins estimated from the Perrin equation, were to be 45,258$A^3$ and 17,608$A^3$ in water and organic solvent, respectively. These values indicate that a trimerization is possibly occurring in the aqueous environment. As an auxiliary experiment for the calculation of the molecular volume using Perrin equation, fluorescence quenching constants ($K_q$) with the quencher acrylamide and fluorescence lifetimes (${\tau}_F$) of the intrinsic fluorophore tryptophan residue were estimated in the two different solvent systems. $K_q$ in water was 18.21$M^{-1}$ and it was 46.24$M^{-1}$ in organic solvent. Fluorescence lifetimes of tryptophan residue were calculated to be 2.80 nsec. in water and 3.81 nsec. in organic solvent, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.2
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• pp.47-55
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• 1987

Recently, in precision working, precision is in submicron. Therefore, when we measure various finished goods in superfine measurement, because it is relatively difficult to disregard effect of surroundings, these effect of surroundings must be compensated or canceled. In this study, for roundness measurement, three point method is researched which is able to cancel the effect of rotation accuracy of axis and eccenricity of workpiece. It is difference between this three point method and tradi- tional three point method whose measuring apparatus have three movable pickups posit- ioned with angle and between the pickups. As a results, when rotation accuracy of axis is varied from $0.02\mu\textrm{m}$ to $0.05\mu\textrm{m}$ the width of variation of measured roundness is $0.04\mu\textrm{m}$. And, when eccentricity of workpiece is varied from 0 to $4\mu\textrm{m}$, the width of variation of measured roundness is $0.005\mu\textrm{m}$. These error width are disregardable because they are in 10% of measured roundness. Therefore, by this three point method, the effect of rotation accuracy of axis and the effect of eccentricity of workpiece are canceled. And we are able to select the angle between the pickups ($\phi$ and $\tau$) by means of relation between $F_{k}$ and K.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.11A
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• pp.1682-1690
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• 2000

최근들어 초광대역 시간 도약 임펄스 무선 전송(ultra wideband time hopping impulse radio; 이하 IR) 기술이 실내 무선 LAN이나 군용 무선 통신 시스템 등을위한 새로운대역 확산 전송 방식으로서 큰 관심을 모으고 있다 IR 시스템은 1(nsec) 이하의 매우 짧은 펄스폭의 펄스 위치 변조(pulse position modulation)된 가우시안 모노사이클 펄스열을 이용함으로서 매우작은 크기 의수 GHz에 이르는 초광대역 스펙트럼을 가지며 기존의 통신 시스템에 거의 간섭을 미치지 않으면서 사용 가능하다. 본 논문에서는 IR 시스템에 M진 (M-ary) PPM 방식을 적용하는 경우의 성능을 평가하였다. 특시 의사 잡음 부호 발생기와 10진 변환기(decimator)로 구성된 시간 도약 패턴을 사용하여 다원 접속 간섭이 배제되는 부가성 백색 가우시안 잡음 채널 하의 동기식(synchronous) IR 시스템에서, 심벌 수, M, 가우시안 모노사이클 펄스 폭 $\tau$$_{p}$, PPM에서 펄스 간 간격$\delta$, 펄스 반복 횟수 N$_{s}$ 등과 같은 다양한 시스템 파라미터의 조합에 따른 성능 변화를 모의 실험을 통해 확인하였으며, 이러한 결과를 통해 비트 오율, 시스템 복잡도 및 전송율 등의 사양에 따라 적합한 M 진 PPM IR 시스템의 구성 방안에 대한 근거를 제공하였다.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2007.04a
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• pp.25-44
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• 2007

The glucocorticoid receptor (GR) is an intracellular protein that is widely distributed throughout hippocampal and neocortical brain tissue. Mifepristone (RU486) is a potent GR antagonist that has also been shown to exhibit partial agonist-like effects. The precise location of the GR domain involved in the agonist-like activity of RU486 is unknown. Here, we examine this aspect of GR signaling by comparing human GR (hGR) construct with a Guyanese squirrel monkey GR (gsmGR) construct in which nuclear translocation and transactivation are known to be impaired. Using an objective translocation scoring method, we found that both hGR and gsmGR are translocated by RU486, and that nuclear translocation of hGR is significantly increased compared to gsmGR at 10 nM, 100 nM and 1000 nM RU486 in transiently transfected COS1 cells. While addition of RU486 to the cells transfected with hGR results in a 16-fold dose-dependent increase in transactivation compared to non-treated cells, no significant change in transactivation is observed with gsmGR at doses up to 100 nM RU486. Further experiments using six GR chimeras indicate that replacement of the hGR carboxyl-terminus of tau-1 transactivation domain (C-AF1, amino acids 132-428) with that from gsmGR diminishes hGR transactivation by RU486. These results demonstrate that RU486-induced transactivation of GR is determined in part by amino acids in the C-AF1 domain.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.3
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• pp.195-203
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• 2013

In this study, antioxidative effects of the extracts of different species and flowering periods of Inula britannica were investigated. According to the free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity of the extracts, The I. britannica var. chinensis flower extract (500 ${\mu}g/mL$) was measured in a 79.89% free radical scavenging activity, but the flower extracts of similar species (I. britannica var. linariaefolia Regel, I. britannica var. ramosa, I. salicina var. asiatica) did not show any effect on the free radical scavenging activity. The effects of the free radical scavenging activity of I. britannica var. chinensis flower extracts were exhibited in the order of full bloom (93.68%), bud (43.28%), and fallen blossom (14.11%). Next, we established optimum condition of extract solvent, temperature, extraction time. The extract from ethanol at $60^{\circ}C$ showed the most free radical scavenging activity among other conditions and extraction time not relevant in free radical scavenging activity. The protective effects of the extract of I. britannica var. chinensis flower on the photohemolysis of human erythrocytes by using rose bengal were increased in a concentration-dependent manner (5 ~ 50 ${\mu}g/mL$). In particular, the extract in 50 ${\mu}g/mL$ concentration exhibited better protective activity (${\tau}_{50}$ = 116.1 min) than (+)-${\alpha}$-tocopherol (${\tau}_{50}$ = 73.44 min), which is a known lipophilic antioxidant. Principle component of I. britannica var. chinensis flower was identified as quercetin of flavonoids by high-performance liquid chromatography (HPLC). These results indicate that the extract of I. britannica var. chinensis flower can function as antioxidants in biological systems, particularly skin exposed to UV radiation by scavenging free radical and $^1O_2$, and protect cellular membranes against ROS. It is concluded that the antioxidative effects of the extract of I. britannica var. chinensis flower could be applicable to functional cosmetics.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.283-293
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• 2006

The purpose of this study is to quantitatively estimate the erosional properties for cohesive sediments on Keum Estuary. Then the spatial variation was evaluated, through analyzing and comparing the seasonal variation of the erosional properties in Keum Estuary with that of the erosional properties in the other sites. As erosional properties of cohesive sediments are also influenced largely by basic physico-chemical property of cohesive sediments themselves, the impact that the basic physico-chemical property has on the erosional properties is analyzed in this study. Erosional tests are performed under the condition of uniform beds. Total 8 times of tests using an annular flume are also conducted in a location, low times respectively by seasons: the fall, winter. Experimental results of erosional tests show that the critical shear stress for erosion varies in the range of $0.12{\sim}0.36N/m^2$ and the coefficient of erosion rate varies in the range of $120.91{\sim}6.72mg/cm^2{\cdot}hr$, over the corresponding bulk-density range $1.15{\sim}1.34g/cm^3$. Although the calculated parameters of erosional properties are remarkably different in quantity compared with those of other cohesive sediments(lake Okeechobee) and Kaolinite, their seasonal variabilities within Keum Estuary appear to be insignificant.