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

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.2
• /
• pp.155-160
• /
• 2020

Ga₂O₃/n-type 4H-SiC heterojunction diodes were fabricated by RF magnetron sputtering. The optical properties of Ga₂O₃ and electrical properties of diodes were investigated. I-V characteristics were compared with simulation data from the Atlas software. The band gap of Ga₂O₃ was changed from 5.01 eV to 4.88 eV through oxygen annealing. The doping concentration of Ga₂O₃ was extracted from C-V characteristics. The annealed oxygen exhibited twice higher doping concentration. The annealed diodes showed improved turn-on voltage (0.99 V) and lower leakage current (3 pA). Furthermore, the oxygen-annealed diodes exhibited a temperature cross-point when temperature increased, and its ideality factor was lower than that of as-grown diodes.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2014.11a
• /
• pp.213-213
• /
• 2014

$300^{\circ}C$와 $500^{\circ}C$에서 아크 이온 증착된 도포층의 조성은 각각 Fe : Al : Ti : Si : N = 1.31 : 36.52 : 31.31 : 0.48 : 30.38 [wt.%]와 Fe : Cr : Al : Ti : Si : N = 1.24 : 0.56 : 36.82 : 32.72 : 0.59 : 28.07 [wt.%] 이었다. 0.1N $H_2SO_4$ 수용액과 인공해수 (ASTM D1141-98) 분위기에서 $300^{\circ}C$, $500^{\circ}C$에서 증착된 도포층의 부식전압과 부식속도는 각각 $-0.2787V_{SHE}$, $0.002A/cm^2$, $-2.764V_{SHE}$, $0.002A/cm^2$ 와 $-0.2799V_{SHE}$, $0.002A/cm^2$, $-0.0394V_{SHE}$, $0.002A/cm^2$이었다. 나노 경도값은 각각 23.6, 25.8 GPa 이었다. 이는 각각 2208.2, $2434.2H_V$에 해당되었다.

• Journal of the Korean Society for Heat Treatment
• /
• v.4 no.2
• /
• pp.19-26
• /
• 1991

This study has been constructed to establish the formation of the VC layer on various steels by immersion in fused borax bath containing Fe-V powder. The result obtained from the experiment are as follows. (1) The carbide is supposed to grow on the front surface of the carbide layers by the reaction between carbide-forming elements dissolved in the fused borax and carbon atoms successively supplied through the layer from the matrix. (2) The growth rate of the carbide layers was controlled by the diffusion rate of C in the carbide layer and C content in the matrix. (3) Carbide layer formed on the surface of the specimen is VC layer and the hardness of this layer is above $H_v$ 3000.

• Korean Journal of English Language and Linguistics
• /
• v.4 no.2
• /
• pp.117-149
• /
• 2004

The paper is to argue against the asymmetric CP-V2 analysis of Old English, according to which finite verbs invariably undergo movement into a clause-final T within subordinate clauses and reach the functional head C within main clauses. The asymmetric CP-V2 analysis, first of all, faces difficulty in explaining a wide range of post-verbal elements within subordinate clauses. To resolve the problem, the analysis has to abandon the obligatoriness of V-to-T movement or introduce various types of extraposition whose status is dubious as a legitimate syntactic operation. Obligatory V-to-T movement in Old English lacks conceptual justification as well. Crosslinguistic evidence reveals that morphological richness in verbal inflection cannot entail overt verb movement. Moreover, the operation is always string-vacuous under the asymmetric CP- V2 analysis and has no effect at the interfaces, in violation of the principle of economy. The distribution of Old English finite verbs in main clauses also undermines the asymmetric CP-V2 analysis. Conceptually speaking, a proper syntactic trigger cannot be confirmed to motivate obligatory verb movement to C. The operation not only gets little support from nominative Case marking, the distribution of expletives, or complementizer agreement but also requires the unconvincing stipulation that expletives as well as sentence-initial subjects result from string-vacuous topicalization. Finally, textual evidence testifies that Old English sometimes permits non-V2 ordering patterns, many of which remain unexplained under the asymmetric CP-V2 analysis.

• Journal of Radiation Protection and Research
• /
• v.26 no.3
• /
• pp.287-290
• /
• 2001

The 9.17MeV gamma-rays from the $^{13}C(p,\;{\gamma})^{14}N,\;^{14}N({\gamma},\;{\gamma})^{14}N$ reactions were measured. The incident 9.17MeV gamma-ray was produced from the $^{13}C(p,\;{\gamma})^{14}N$ reaction at Ep=1.75MeV resonance. The 1.75MeV proton beam was accelerated using the 3MV SNU-AMS Tandetron and 1.7MV KIGAM Tandem accelerators. The enriched 13C target was $121{\mu}g/cm^2$ self-supporting foil, and we used liquid nitrogen as a resonant absorption target. We used a HP-Ge detector with 30% efficiency and less 2keV energy resolution. We developed new method to detect the scattered 9.17MeV gamma-ray from the nitrogen target by using the energy difference between the Doppler shifted gamma-ray from the $^{13}C(p,\;{\gamma})^{14}N$ reaction and the resonant absorbed and rescattered gamma-ray from the $^{14}N({\gamma},\;{\gamma})^{14}N$ reaction.

• Journal of the Korean Society of Tobacco Science
• /
• v.25 no.2
• /
• pp.95-102
• /
• 2003

To get the informations of quality uniformity of threshed burley tobacco produced from 1997 to 2001 and processed at various leaf processing factories, chemical constituents contents and coefficient of variation(C.V.) were analysed. The average chemical constituents contents of 12 grades during 5 years ranged as follows; nicotine 1.76～2.66%, total nitrogen 4.15～4.80%, crude ash 21.6～22.4% and chlorine 1.08～1.20%. The variations of chemical constituents contents among crop years was higher in nicotine while lower in crude ash. The nicotine content of upper leaves were influenced negatively by rainfalls, while total nitrogen content were influenced positively by air temperature and sunshine hours during July. The C.V. of chemical content in same grade was higher in chlorine and nicotine while lower in crude ash. The ratio of C.V. among leaf tobacco processing factories/C.V. of total sample in same grade was high in nicotine. To reduce the C.V. of chemical constituents, it is recommendable to thresh the leaf tobacco at one processing factory. When the leaves being processed at one factory, the decreasing effect of deviation was higher in nicotine, particularly.

• Microbiology and Biotechnology Letters
• /
• v.9 no.2
• /
• pp.91-97
• /
• 1981

A thermophilic soil isolate Bacillus sp. Y-127 was selected for the production of thermostable amylase. The strain was used for the enzyme production and the thermostable amylase was characterized. The optimum cultural conditions for the enzyme production were 6$0^{\circ}C$ at pH 7.0 for 32 hours using a mineral medium containing 2% soluble starch and 0.2% yeast extract. The extra-cellular enzyme was purified about 123-folds with about 6% recovery. The purified enzyme was stable at pH between 4.0 and 7.0, and temperature up to 6$0^{\circ}C$.

• Journal of Korea Society of Industrial Information Systems
• /
• v.19 no.2
• /
• pp.31-36
• /
• 2014

In this paper, we developed an intergrated piezoresistive temperature and humidity sensor using nano-technology, and evaluated the properties. In the measuring range from $20^{\circ}C$ to $80^{\circ}C$, output sensitivity of temperature was about 0.75mV/$1^{\circ}C$. Output sensitivity of humidity was about 1.35mV/10%(RH). Therefore, developed sensor suggests that it is possible applicable to the general residential environment.

• Journal of Sensor Science and Technology
• /
• v.10 no.6
• /
• pp.328-337
• /
• 2001

The stochiometric mix of evaporating materials for the $CdGa_2Se_4$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CdGa_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $630^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CdGa_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $8.27{\times}10^{17}cm^{-3}$, $345\;cm^2/V{\cdot}s$ at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the $CuInSe_2$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}So$ and the crystal field splitting ${\Delta}Cr$ were 106.5 meV and 418.9 meV at 10 K, respectively. From the photoluminescence measurement on $CdGa_2Se_4$ single crystal thin film, we observed free excition ($E_x$) existing only high quality crystal and neutral bound exiciton ($D^{\circ}$, X) having very strong peak intensity. Then, the full-width-at -half-maximum(FWHM) and binding energy of neutral donor bound excition were 8 meV and 13.7 meV, respectivity. By Haynes rule, an activation energy of impurity was 137 meV.