• Communications of the Korean Mathematical Society
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• v.27 no.3
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• pp.557-564
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• 2012

This study concerns the existence of positive solution for the following nonlinear system $$\{-div(|x|^{-ap}|{\nabla}u|^{p-2}{\nabla}u)=|x|^{-(a+1)p+c_1}({\alpha}_1f(v)+{\beta}_1h(u)),x{\in}{\Omega},\\-div(|x|^{-bq}|{\nabla}v|q^{-2}{\nabla}v)=|x|^{-(b+1)q+c_2}({\alpha}_2g(u)+{\beta}_2k(v)),x{\in}{\Omega},\\u=v=0,x{\in}{\partial}{\Omega}$$, where ${\Omega}$ is a bounded smooth domain of $\mathbb{R}^N$ with $0{\in}{\Omega}$, 1 < $p,q$ < N, $0{{\leq}}a<\frac{N-p}{p}$, $0{{\leq}}b<\frac{N-q}{q}$ and $c_1$, $c_2$, ${\alpha}_1$, ${\alpha}_2$, ${\beta}_1$, ${\beta}_2$ are positive parameters. Here $f,g,h,k$ : $[0,{\infty}){\rightarrow}[0,{\infty})$ are nondecresing continuous functions and $$\lim_{s{\rightarrow}{\infty}}\frac{f(Ag(s)^{\frac{1}{q-1}})}{s^{p-1}}=0$$ for every A > 0. We discuss the existence of positive solution when $f,g,h$ and $k$ satisfy certain additional conditions. We use the method of sub-super solutions to establish our results.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.120-120
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• 1999

III-nitride계 물질들은 blue와 UV 영역의 LED, LD와 같은 광소자뿐만 아니라 HBT, FET와 같은 전자소자로도 널리 응용되고 있다. 이와 같은 물질을 이용한 소자를 제작할 수 있는 낮은 저항의 ohmic contact은 필수적이다. Al이나 Ti와 같은 물질을 기초로 한 n-GaN의 경우는 이미 많은 연구결과가 발표되어 전기적 광학적 소자를 동작하는데 충분히 낮은 ohmic contact저항( )을 었다. 그러나 p-GaN의 ohmic contact은 아직까지 많은 문제점을 내포하고 있다. 그 중의 하나는 높은 doping 농도( )의 p-GaN 박막을 성장하기가 어렵다는 것이며, 또 하나는 낮은 접촉 비저항을 얻기 위해선 7.5eV이상의 큰 재가 function을 지닌 금속을 선택해야 한다. 그러나 5.5eV 이상의 재가 function을 갖는 금속은 존재하지 않는다. 위와 같은 문제점들은 p-GaN의 접촉 비저항이 이상의 높은 값을 갖게 만들고 있으며, 이에 대한 해경방안으로는 고온의 열처리를 통하여 p-GaN와 금속 사이에서 화학적 반응을 일으킴으로써 표면 근처에서 캐리어농도를 증가시키고, 캐리어 수송의 형태가 tunneling 형태로 일어날 수 있도록 하는 tunneling current mechanism을 이용하는 것이다. 이로 인해 결국 낮은 접촉 비저항을 얻을 수 있게되며, 일반적으로 p-GaN에서는 Nidl 좋은 물질로 알려져 있다. 그러나 Ni은 50$0^{\circ}C$이상의 열처리에서 쉽게 산화되는 특성 때문에 높은 캐리어를 얻는데 어려운 문제점이 있다. 이에 본 연구에서는 MBE로 성장된 p-GaN박막을 Mg의 activation을 더욱 증가시키기 위해 N2 분위기에서 15분간 90$0^{\circ}C$에서 annealing을 하였으며, ohmic 접촉을 위한 금속으로 높은 재가 function과 좋은 adhesion 그리고 낮은 자체저항을 가지고 있는 Ni/Au를 ohmic metal로 하여 contact한 후에 90$0^{\circ}C$에서 10초간 rapid thermal annealing (RTA)처리를 했다. 성장된 박막의 광학적 성질은 PL로써 측정하였으며, photoconductivity 실험을 통해 impurity의 life time을 분석하였고, persistent photoconductivity를 통해 dark current를 측정하였다. 또한 contact resistance를 계산하기 위해 circular-TLM method을 이용하여 I-V 특성을 조사하였다.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.314-320
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• 1999

Several bisphosphine- and bisphosphite-substituted Re-imido complexes have been prepared from Re(NPh)(PPh3)2Cl3, 1, and Re(N-C6H3-i-Pr2)2Cl3(py), 4. Compound 1 reacted with trimethyl phosphate (P(OMe)3) to give a mixture of two isomers,mer,trans-Re(NPh)(P(OMe)3)2Cl3, 2, and fac,cis-Re(NPh)(P(OMe)3)2Cl3, 2a. In this reaction, the mer,trans-isomer is a major product. Complex 1 also reacted with triethylphosphine (PEt3) to exclusively give mertrans-Re(NPh)(PEt3)2Cl3, 3. Compound 4 reacted with trimethylphosphine (PMe3) to give mer,trans-Re(N-C6H3-i-Pr2)(PMe3)2Cl3, 5, which was converted to mer-Re(N-C6H3-i-Pr2)(PMe)(OPMe3)Cl3, 6, on exposure to air. Crystallographic data for 2: monoclinic space group P21/n, a = 8.870(2) Å, b = 14.393(3) Å, c = 17.114(4) Å, β = 101.43(2)°, Z = 4, R(wR2) = 0.0521(0.1293). Crystallographic data for 5: orthorhombic space group P212121, a = 11.307(l) Å, b = 11.802(l) Å, c = 19.193(2) Å, Z = 4, R(wR2) = 0.0250(0.0593). Crystallographic data for 6: orthorhombic space group P212121, a = 14.036(4) Å, b = 16.486(5) Å, c = 11.397(3) Å, Z = 4, R(wR2) = 0.0261(0.0630).

• Microbiology and Biotechnology Letters
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• v.13 no.3
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• pp.173-178
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• 1985

Extracellular amylase from tile filtrate of the submerged culture of Ganoderma lucidum was partially purified by ammonium sulfate precipitation and its properties were studied. The optimum pH and temperature of the enzyme activity were 5.5 and 5$0^{\circ}C$. respectively. This enzyme was most stable at pH 5.0 and stable up to 3$0^{\circ}C$, but it lost completely the activity when it was treated at 6$0^{\circ}C$ for 10 min. The enzyme was activated by the addition of M $n^{++}$, $C^{++}$ and C $u^{++}$, but inhibited by H $g^{++}$, A $g^{++}$ And various enzyme inhibitors and chemical reagents did not affect the enzyme activity. The enzyme hydrolyzed the boiled amylaceous polysaccharides, but it hydrolyzed raw starches very slowly. The activation energy of the enzyme for soluble starch was calculated and found to be 7.06 Kcal per mole. The Km values of the enzyme for soluble starch, amylose, amylopectin and glycogen were 0.16, 0.37, 0.19, and 0.16mg/$m\ell$, respectively. Maltose was found to inhibit the enzyme activity and kinetic analysis revealed a competitive type of inhibition.n.n.n.n.n.

• Animal Bioscience
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• v.36 no.6
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• pp.962-972
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• 2023

Objective: This study determined the effects of dietary treatments and castration on meat quality, fatty acids (FAs) profiles, and volatile compounds in Korean native black goats (KNBG, Capra hircus coreanae), including the relationship between the population of rumen microbiomes and meat FA profiles. Methods: Twenty-four KNBG (48.6±1.4 kg) were randomly allocated to one of four treatments arranged into a 2×2 factorial structure. The factors were dietary forage to concentrate ratio (high forage [HF, 80:20] and low forage [LF, 20:80]), and a castration treatment (castration [CA] vs non-castration [NCA]). Results: Among meat quality traits, the CA group exhibited a higher percentage of crude fat and water holding capacity (p<0.05). The profiles of the saturated fatty acid (SFA) in meat sample derived from CA KNBG showed a significantly lower percentage compared to NCA individuals, due to the lower proportion of C14:0 and C18:0. Feeding a high-forage diet to KNBG increased the formation of C18:1n7, C18:3n3, C20:1n9, C22:4n6 in meat, and polyunsaturated fatty acid (PUFA) profiles (p<0.05). Consequently, the n6:n3 ratio declined (p<0.05). There was an interaction between dietary treatment and castration for formation of C20:5n3 (p<0.05), while C18:1n9, C22:6n3, monounsaturated fatty acid (MUFA) and the MUFA:SFA ratio were influenced by both diet and castration (p<0.05). Nine volatile compounds were identified and were strongly influenced by both dietary treatments, castration (p<0.05), and their interaction. In addition, principal component analysis (PCA) revealed distinctly different odor patterns in the NCA goats fed LF diets. Spearman correlation analysis showed a high correlation between rumen bacteria and meat PUFAs. Conclusion: These results suggest the essential effects of the rumen microbial population for the synthesis of meat FAs and volatile compounds in KNBG meat, where dietary intake and castration also contribute substantially.

• Biomedical Science Letters
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• v.11 no.3
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• pp.259-266
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• 2005

Mast cells and goblet cells have been known to protect the host against parasites. In this study, we examined the response of the mast cells and goblet cells over a period of 6 weeks in the duodenum, jejunum and ileum of C3H/HeN and C57BL/6 mice infected with Echinostoma hortense (E. hortense). In addition, we investigated whether the worm recovery rate of uninfected mice (the control group) or E. hortense-infected mice (the experimental group) was associated with the number of mast cells and goblet cells. The worm recovery rate was higher in the C3H/HeN mice than in the C57BL/6 mice. The number of goblet cells significantly increased in the experimental group of the C3H/HeN and C57BL/6 mice compared with the control group of both strains (P<0.005). Worm recovery peaked 3 weeks after the infection of the C57BL/6 mice and at 2 weeks after the infection of the C3H/HeN mice, and it was higher in the duodenum than in the jejunum and ileum. However, the infected site in the intestine had no relation with worm expulsion. In the C3H/HeN and C57BL/6 mice, the number of goblet cells in the experimental group was significantly higher than that in the control group (P<0.005). The number reached a peak 2 weeks after the infection and it even increased in duodenum, jejunum and ileum. The increased number of goblet cells was retained 6 weeks after infection. The number of goblet cells was higher in the C3H/HeN mice than in the C57BL/6 mice (P<0.01). These results indicate that goblet cells are related with the worm expulsion. Furthermore, immunohistostaining of the antral intestinal walls for lectin showed the significant increase of the number of goblet cells in the experimental group (P<0.001). The high infection rate in the duodenum was found during the early infection. An increased infection rate in the jejunum and ileum was found 3 weeks after infection and the infection rate was higher in the C3H/HeN mice than in the C57BL/6 mice. Taken together, the present study indicates that goblet cells, rather than mast cells, may play critical roles in parasite expulsion.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.710-721
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• 1999

This study was conducted to investigate the hematological characteristics and risk factors of hypercholesterolemia(HC) in Korean. 344 adult men who took the annual health check ups at D or J hospitals were participated in this cross sectional study. The subjects were grouped by plasma total cholesterol level into three groups: normal cholesterolemic(n=139), borderline hypercholesterolemic (n=93) and hypercholesterolemic(n=112) groups. The data of systolic and diastolic blood pressure (SBP/DBP), hemoglobin, plasma glucose, albumin and cholesterol levels were collected from medical records. The levels of plasma triglyceride(TG), HDL C, phospholipid, insulin, apo A and apo B were measured. The levels of plasma LDL C, VLDL C and atherogenic index(AI) were calculated. The subjects with HC had significantly higher SBP and DBP, albumin, TG, phospholipid, HDL C, LDL C, VLDL C and apo B level than those of the normal subjects. The relative and attributable risks on HC were 1.59 and 0.18 for hypertension(SBP/DBP$\geq$160/95), 2.08 and 0.35 for hypertriglyceridemia (TG $\geq$400mg/dl). Plasma total cholesterol level was positively correlated with several hematologic parameters: age(r=0.1242, p<0.05), DBP(r=0.1194, p<0.05), albumin(r=0.2029, p<0.001), plasma TG(r= 0.3829, p<0.001), phospholipid(r=0.6036, p<0.001), LDL C(r=0.8572, p<0.001), HDL C(r=0.2399, p< 0.001), AI(r=0.3116, p<0.001), apo B(r=0.2602, p<0.05) and Lp(a)(r=0.1372, p<0.05). However, plasma total cholesterol level was negatively correlated with the levels of Apo A1(r= 0.2922, p<0.001), and ABR(r= 0.3598, p<0.001).

• Journal of the Korean Chemical Society
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• v.16 no.5
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• pp.314-319
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• 1972

N-Methyl-p-aminophenol was polymerized by oxidative couplng in the aqueous iron chelate solution in the presence of oxygen, and black precipitate of oligo-(N-methyl-p-aminophenol) was formed quantitatively. In this oxidative polymerization reaction, methyl group attached to N in the monomer was partly eliminated, and it was clarified by the infrared spectra from the fact that the absorption of ${\delta}\;asym\;CH_3\;1460\;cm^{-1}$ and ${\delta}\;sym\;CH_3\;1380\;cm^{-1}$ in acetone insoluble fraction was much weaker than that in acetone soluble fraction. From Thermo-gravimetric analysis, oligo-(N-methyl-p-aminophenol) showed about 40% weight loss at $600^{\circ}C$ and it was less heat-resistant than oligo (p-aminophenol) that methyl group was not contained. In pyrolysis of oligo-(N-methyl-p-aminophenol) in He atmosphere, monomer N-methyl-p-aminophenol and water were formed, and in the pyrolytic gases, $H_2,\;CO,\;CO_2$ were detected by gas chromatography. From the above facts, to the structural change on oligo-(N-methyl-p-aminophenol) when it was heat-treated, it was considered that original linear structure was partly degraded, and the most of the oligomer was to go in with melt polycondensation to form polymer, and heat-resistant cyclic structure was formed at a time.

• Journal of environmental and Sanitary engineering
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• v.21 no.1 s.59
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• pp.21-34
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• 2006

To investigate anti-HIV-1 activity of water soluble chitosans, sulfated chitosan derivatives were prepared in mild condition. Various sulfated chitosan derivatives (N-3,6-O-S-chitosan, N-desulfated 3,6-O-S-chitosan, 3,6-O-S-chitin, and 3,6-O-sulfated-N-(o-carboxybenzoyl) chitosan) were synthesized with sulfurtrioxidepyridene complex in pyridine solvent. Characterization of the sulfated chitosan derivatives was carried out by $^{13}C$ NMR and IR spectroscopies. To observe ionic reaction properties, pKas of the sulfated chitosan derivatives and chitosan of low molecular weight were estimated by potentiometric titration. The sulfated chitosan derivatives had high water solubility, pKas (pKa : 7.7) of N-3,6-O-S-chitosan and N-desulfated 3,6-O-S-chitosan were increased than pKa of water insoluble chitosan (pKa : 6.2), These results suggest the participation of electrostatic interaction of amino and sulfate groups on the sulfated chitosans. Anti-HIV-1 drugs, such as AZT, ddC, and ddI for anti-HIV activity had higher selective index compared with SCB-chitosan but N-3,6-O-S-chitosan has shown higher selective index compared with ddC and ddI as HIV drugs.. These results suggest that sulfated chitosan derivatives were expected as an anti-HIV drug with differential driving force mechanism against some nucleoside analogs drug in the future.

• Journal of the Korean Electrochemical Society
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• v.13 no.3
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• pp.198-202
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• 2010

Lithium co-polyelectrolyte-ionic liquid systems, using poly (lithium 2-acrylamido-2-methyl propanesulfonate; PAMPSLi) and polyvinyl formamid (PVF) were prepared and their electrochemical and physical properties were measured. The conductivity of co-polymer systems, PAMPSLi/PVF/N, N-dimethyl-N-propyl-N-butylammonium tricyanomethanide (PAMPSLi/PVF/$N_{1134}$TCM) and PAMPSLi/PVF/N, N-dimethyl-N-propyl-N-butylammonium dicyanamide (PAMPSLi/PVF/$N_{1134}$DCA) exhibited low viscosity ($N_{1134}$TCM:$N_{1134}$DCA 28.6cP, 28.7cP) and higher conductivity ($2.48{\times}10^{-3}Scm^{-1}$, $2.2{\times}10^{-3}Scm^{-1}$) than homopolymer system. The ionic conductivity PAMPSLi/PVF/1-ethyl-3-methyl imidazolium dicyanamide (PAMPSLi/PVF/emImDCA) exhibited $1.54{\times}10^{-3}Scm^{-1}$ and low viscosity (emImDCA: 28.09cP). High flexibility of imidazolium cation and dissociation of lithium cation from the co-polymer chains were affected by high conductivity and low viscosity.