• Bulletin of the Korean Mathematical Society
• /
• v.50 no.4
• /
• pp.1201-1207
• /
• 2013

Let N be a complete Riemannian manifold with nonnegative Ricci curvature and let M be a complete noncompact oriented stable minimal hypersurface in N. We prove that if M has at least two ends and ${\int}_M{\mid}A{\mid}^2\;dv={\infty}$, then M admits a nonconstant harmonic function with finite Dirichlet integral, where A is the second fundamental form of M. We also show that the space of $L^2$ harmonic 1-forms on such a stable minimal hypersurface is not trivial. Our result is a generalization of one of main results in [12] because if N has nonnegative sectional curvature, then M admits no nonconstant harmonic functions with finite Dirichlet integral. And our result recovers a main theorem in [3] as a corollary.

• Journal of the Korean Chemical Society
• /
• v.56 no.4
• /
• pp.464-467
• /
• 2012

A novel chitosan derivative with double quaternary ammonium salt-2-pyridine-acetyl-N-trimethyl chitosan chloride (PATMCS) was synthesized and the antioxidant activity of PATMCS against hydroxyl radicals was assessed. The results indicated that PATMCS had potent hydroxyl scavenging activity. The $IC_{50}$ of PATMCS was 0.13 mg/mL. PATMCS showed 100% scavenging effect at a dose of 0.8 mg/mL which markedly better than that of N-trimethyl chitosan chloride (TMCS). It was confirmed that quaternary chitosan derivatives showed potent antioxidant activity. PATMCS has double quaternary ammonium salt structure in the molecules. Therefore, the antioxidant activity of PATMCS was better than TMCS. The above results are theoretically fundamental for further development and making use of chitosan resources to prepare new antioxidants.

• Proceedings of the KSPS conference
• /
• 2000.07a
• /
• pp.189-198
• /
• 2000

/$t{\partial}n$/, /$d{\partial}n$/, /$t{\partial}l$/ and /d{\partial}l$/, on the one hand, are the typical phonemes of syllabic consonants. On the other hand, /${\int}{\partial}n$/ most plausibly gives rise to the syllabic consonants. /$t{\partial}r$/ and /$d{\partial}r/ can he syllabic. However, because lip-rounded consonants strengthen the character of consonantal phonemes, they are not so appropriate. Apart from phonemes, some familiar words also could be almost always syllabic. From the historical perspective, we can say that the position of syllabic consonants is typically the second syllables of two-syllabic words and 1.hat the underlying schwa does not always exist. In terms of the syllable structure, the syllables which include syllabic consonants are totally different from both stressed syllables and the other unstressed syllables.

• Journal of Korean Society on Water Environment
• /
• v.23 no.6
• /
• pp.966-972
• /
• 2007

A novel organoclay has been developed with aluminium-pillared clay modified with an amphoteric surfactant, N-Dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (DDAPS). This novel organoclay is expected to have phosphorus removal capacity as well as organic and inorganic contaminant removal capacity, due to aluminum inside the clay structure. It also exhibited less surfactant desorption than conventional cation surfactant-based organoclays. Phosphorus in water can be decreased from 0.2 mg/L to 0.0012 mg/L in 27 hours with this organoclay. Also, cadmium could removed from water using this proposed organo-clay. Experiments were performed under various pHs and amphoteric surfactants sorption capability was the highest at pH 5 when more of the amphoteric surfactant head group took on positive charges.

• Bulletin of the Korean Chemical Society
• /
• v.21 no.1
• /
• pp.39-43
• /
• 2000

New coordination polymers of general form, $$[CoL_2X_2]_n$$ (L = 3,3'-oxybis(pyridine) (obp), 1,4-bis(3-pyri-doxy) benzene (bpob); X = Cl, NCS), have been prepared via a slow diffusion method. The reaction of the present linkers with cobalt(II) ion affords infinite 2-dimensional sheet products. For $[Co(obp) $_2Cl_2]_n$$, the local geometry of the cobalt center is an octahedral arrangement with four nitrogen donors and two chlorine ions in trans positions. $$[Co(bpob)_2(NCS)_2]_n$$ has provided a similar structure: the local geometry of the cobalt atom is an octahedral arrangement with four pyridine units and two NCS groups in transpositions. The obp and bpob linkers connect two cobalt(II) ions defining the edges of 40- and 60-membered $[Co(II)]_4$ ring, respectively. Thermal analyses of the coordination polymers show significant thermal behavior associated with the characteristic structures.

• Korean Journal of Pharmacognosy
• /
• v.38 no.1
• /
• pp.31-36
• /
• 2007

In this study, we have investigated the antioxidant activities of the leaves of Smilax china Linne in order to find the antioxidant substances which has an scavenging effect of reactive oxygen species (ROS) from natural products. As a result, EtOAc and n-BuOH extracts of the leaves of Smilax china Linne exhibited potent antioxidant effect on various antioxidant experiment. The major components of antioxidant activity were isolated from EtOAc and n-BuOH extracts of the leaves of Smilax china Linne. Their structure of compounds were identified as kaempferol-7-O-${\alpha}$-L-rhamnopyranoside and kaempferol-3,7-O-${\alpha}$-L-dirhamnopyranoside by spectroscopic evidence, respectively. Antioxidant activities were observed in kaempferrol-7-O-${\alpha}$-L-rhamnopyranoside at 23 ${\mu}g$ and in kaempferol-3,7-O-${\alpha}$-L-dirhamnopyranoside at 27 ${\mu}g$ as concentration of DPPH 50% reduction.

• Bulletin of the Korean Mathematical Society
• /
• v.48 no.6
• /
• pp.1245-1252
• /
• 2011

Consider the $L^2$-adjoint $s_g^{'*}$ of the linearization of the scalar curvature $s_g$. If ker $s_g^{'*}{\neq}0$ on an n-dimensional compact manifold, it is well known that the scalar curvature $s_g$ is a non-negative constant. In this paper, we study the structure of the level set ${\varphi}^{-1}$(0) and find the behavior of Ricci tensor when ker $s_g^{'*}{\neq}0$ with $s_g$ > 0. Also for a nontrivial solution (g, f) of $z=s_g^{'*}(f)$ on an n-dimensional compact manifold, we analyze the structure of the regular level set $f^{-1}$(-1). These results give a good understanding of the given manifolds.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.4
• /
• pp.27-32
• /
• 1997

In resonant tunneling diodes with the quantum well structure showing the negative differential resistance (NDR), it is essential to increase both the peak-to-valley current ratio (PVCR) and the peak current desnity ( $J_{p}$) for the accurate digital switching operation and the high output of the device. In this work, a resonant interband tunneling diode (RITD) with single quantum well structure, which is composed of I $n_{0.47}$As/I $n_{0.52}$A $l_{0.48}$As heterojunction on the InP substrate, is fabricated ot improve PVCR and JP, and then the dependence of I-V charcteristics on the width of the quantum well was investigated.d.ted.d.

• Journal of the Korean Chemical Society
• /
• v.14 no.2
• /
• pp.193-199
• /
• 1970

Further validity of the significant structure theory has been tested by calculating the viscosities of binary mixtures-three pairs of $C_6H_6(1)+C_6H_{12}\;(2),\;CCI_4\;(1)+C_6H_6{2}and\l;CCI_4(1)+C_6H_{12}(2)$-and also by calculating the viscosities of n-$C_5H_{12}\;and\;n-C_6H_{14}$ in the pressure range of 1 bar to 4000 bars. The results are quite satisfactory for both cases and provide another evidence for the validity of the significan structure theory.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.4
• /
• pp.59-64
• /
• 2023

In this paper, It is proposed through the empirical design of a Conducted EMI filter for noise reduction of power used in electronic devices. For the proposed structure, A-type, B-type, C-type, and D-type structures were designed, and conductive noise reduction was confirmed by using an LC network with various X-capacitors, Y-capacitors, and Air-inductors. 10 [μH] was used for L1 and L2, and 4.7 [nF] was used for C1 and C2. L3 for common mode used 13[μH], and C5, C6, C7 were designed using 10[nF]. The measured insertion loss values of the designed EMI filter were -74.4[dB] at 3.2MHz, -75.4[dB] at 4MHz, and -75.3[dB] at 13.56MHz. Therefore, the proposed EMI filter will be able to reduce power supply noise used in various electronic devices.