• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제49권8호
• /
• pp.438-444
• /
• 2000

We report the effects of etch process parameters on the ohmic contact formation in the plasma etching of GaN. Planar inductively coupled plasma system with $CH_4/H_2/Ar$gas chemistry has been used as etch reactor. The contact resistance and the specific contact resistance have been investigated using transfer length method as a function of RF bias power and %Ar gas concentration in total flow rate. AES(Auger electron spectroscopy) analysis revealed that the etched GaN has nonstoichiometric Ga rich surface and was contaminated by carbon and oxygen. Especially large amount of carbon was detected at the sample etched for high bias power (or voltage) condition, where severe degradation of contact resistance was occurred. We achieved the low ohmic contact of $2.4{\times}10^{-3} {\Omega}cm^2$ specific contact resistance at the input power 400 W, RF bias power 150 W, and working pressure 10mTorr with 10 sccm $CH_4$, 15 sccm H2, 5 sccm Ar gas composition.

• 한국전기전자재료학회논문지
• /
• 제22권11호
• /
• pp.925-929
• /
• 2009

In this study, $0.95(K_{0.5}Na_{0.5})NbO_3-0.05Li(Sb_{0.8}Nb_{0.2})O_3$ ceramics were investigated as a function of the amount of $Ag_2O$ addition in order to improve dielectric and piezoelectric properties of lead-free piezoelectric ceramics. With increasing the amount of $Ag_2O$ addition, density and electromechanical coupling factor ($k_p$) increased up to 0.2 wt.% $Ag_2O$ and decreased above 0.2 wt.% $Ag_2O$. At the sintering temperature of $1020^{\circ}C$, electromechanical coupling factor ($k_p$), density, dielectric constant (${\varepsilon}r$) and curie temperature (Tc) of ceramics with 0.2 wt% $Ag_2O$ showed the optimal values of 0.42, $4.33\;g/cm^3$, 738 and $393^{\circ}C$, respectively.

• 한국전기전자재료학회논문지
• /
• 제22권7호
• /
• pp.595-601
• /
• 2009

For the silicon oxide $(SiO_x)$ films prepared by using the facing target sputtering (FTS) apparatus that was manufactured to enhance the preciseness of the fabricated thin-film and sputtering yield rate by forming a higher-density plasma in the electrical discharge space for using it as a thin-film passivation system for flexible organic light emitting devices (FOLEDs). The deposition characteristics were investigated under various process conditions, such as array of the cathode magnets, oxygen concentration$(O_2/Ar+O_2)$ introduced during deposition, and variations of distance between two targets and working pressure. We report that the optimum conditions for our FTS apparatus for the deposition of the $SiO_x$ films are as follows: $d_{TS}\;and\;d_{TT}$ are 90mm and 120mm, respectively and the maximum deposition rate is obtained under a gas pressure of 2 mTorr with an oxygen concentration of 3.3%. Under this optimum conditions, it was found that the $SiO_x$ film was grown with a very high deposition rate of $250{\AA}$/min by rf-power of $4.4W/cm^2$, which was significantly enhanced as compared with a deposition rate (${\sim}55{\AA})$/min) of the conventional sputtering system. We also reported that the FTS system is a suitable method for the high speed and the low temperature deposition, the plasma free deposition, and the mass-production.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
• /
• pp.126.2-126.2
• /
• 2011

ZnS thin films were deposited with the radio frequency magnetron sputtering technique at various temperatures and sputtering powers. With the increase in the deposition temperature and the decrease in the radio frequency sputtering power, the crystallinity was increased and the surface roughness was decreased, which lead to the decrease in the electrical resistivity of the film. It is also clearly observed that, the intensity of the (111) XRD peak increases with increasing the substrate temperature. On the other hand, as seen in the FWHM decreased with increasing the substrate temperature. Since the FWHM of the (111) diffraction peak is inversely properties to the grain size of the film, then grain size of ZnS thin film increases with increasing the substrate temperature. The electrical resistivity and optical transmittance of the ZnS film as a function of the post-annealing temperature. It can be seen that with the annealing temperature set at $400^{\circ}C$, the resistivity decreases to a minimum value of $2.1{\times}10^{-3}\;{\Omega}cm$ and the transmittance increases to a maximum value of 80% of the ZnS film.

• 한국유기농업학회지
• /
• 제8권1호
• /
• pp.111-129
• /
• 1999

In order to get some basic data to check the environmental sound function against soil and water pollution and the safe vegetable production by korean organic farming where an internationally recognized basic concepts of soil fertility management for organic farming is not practiced and only applying the organic fertilizer to maintain the soil fertility, the chemical characteristics of soils and $NO_{3}^{-}$ content of chinese cabbage and lettuce cultivated by the conventional farming, greenhouse cultivation and organic farming were investigated. The highest value of $NO_{3}^{-}$-N in 0~30cm subsoil among the three different farming systems was found in the subsoil of organic farming and it was 3.6 and 6.6 times higher than those of conventional farming in chinese cabbage and lettuce respectively. $P_2O_5$ accumulation in the rhizosphere by organic farming also showed the highest value. The accumulation of $NO_{3}^{-}$-N and $P_2O_5$ in organic farming soil were similar or even more higher to those of greenhouse cultivation. The $NO_{3}^{-}$ accumulation in the vegetable by organic farming reached 3224ppm for chinese cabbage and 2543ppm for lettuce, and it were 4.7 and 6.4 times higher than those by conventional farming. It was concluded that there is urgently necessary to introduce the main concepts of soil fertility management of the Basic Standard of IFOAM, EU regulation and FAO/WHO Codex Alimentarius on organic agriculture(draft) into korean organic agriculture for the operation of environmental sound system and the production of sate vegetable in terms of $NO_{3}^{-}$ content.

• 한국토양비료학회지
• /
• 제45권4호
• /
• pp.484-491
• /
• 2012

The hydrological components of a sandy loam soil of nearly level in Chuncheon over 30 years were computed using the E-DiGOR model. Daily simulations were carried out for each year during the period of 1980 to 2009 using standard climate data. Reference evapotranspiration and potential soil evaporation based on Penman-Montheith model were higher during May to August because of the higher atmospheric evaporative demand. Actual soil evaporation was mainly found to be a function of the amount and timing of rainfall, and presumably soil wetness in addition to atmospheric demand. Drainage was affected by rainfall and increased with a higher amount of precipitation and soil water content. Excess drainage occurred throughout rainy months (from July to September), with a peak in July. Therefore, leaching may be a serious problem in the soils all through these months. The 30-year average annual reference evapotranspiration and potential soil evaporation were 951.5 mm and 714.2 mm, respectively. The actual evaporation from bare soil varied between 396.9-528.4 mm and showed comparatively lesser inter-annual variations than drainage. Annual drainage rates below 120 cm soil depth ranged from 477.8 to 1565.9 mm. The long-term mean annual drainage-loss was approximately two times higher than actual soil evaporation.

• Journal of Pharmaceutical Investigation
• /
• 제21권3호
• /
• pp.133-141
• /
• 1991

The fluorescence characteristics of l-anilinonaphthalene-8-sulfonate (ANS) and 2-p-toluidinylnaphthalene-6-sulfonate (TNS) made the dyes useful probes for the determination of the polarity at the binding sites of several water-soluble polyparacyclophanes. Polyparacyclophanes used were 1,6,20,25-tetraaza[ 6.1.6.1]paracyclophane (CPM 44), 1,7,21,27 -tetraaza[7.1.7.1]paracyclophane (CPM 55). 1,7,21,27 -tetraaza-14,34-dioxa[7.1.7.1]paracyclophane (CPE 55) and 1,8,22,29-tetraaza-15,36-dioxa[8.1.8.1] paracyclophane (CPE 66). The fluorescence quantum yield, emission maximum, and half bandwidth of ANS or TNS obtained in a variety of solvent systems were plotted as a function of four kinds of empirical solvent polarity scales such as dielectric constant (D), (D-l)/(2D+1). Y and Z values. It was found that the Z-value-emission maximum $(\overline}V_F,\;cm^{-1})$ profile showed the most reliable linearity. ANS and TNS interacted with CPM 44, CPM 55, CPE 55. CPE 66. ${\alpha}-cyclodextrin$ (CyD) and ${\beta}-CyD$ in the aqueous solution, and from the emission maxima the polarities (Z-value) of their binding sites were calculated to be 92.65, 87.50, 93.35, 84.52, 94.36, and 90.48 for ANS, respectively. and 91.07, 89.68, 85.44, 86.74 and 87.6 for TNS except for ${\alpha}-CyD$, respectively.

• Applied Biological Chemistry
• /
• 제37권6호
• /
• pp.516-521
• /
• 1994

새로운 17종의 imazapyr 유도체인 3-(N-methyl-N(X)-치환-phenylaminooxoacetyl)-2-(4-isopropyl-5-oxo-2-imidazoline-2-yl)pyridine, 6을 합성하고 3-(N-methyl-N(X)-치환-phenylaminooxoacetyl group중의 X-치환기 변화에 따른 구조와 옥수수(Zea mays L.)와 참비듬(Amaranthus viridis L.)에 대한 발아 전의 제초활성에 미치는 관계(SAR)를 검토 한 바, 옥수수의 경우에는 MR상수의 적정값(optimal value)이 $5.56\;cm^3/mol$이었으므로 이 값보다 크거나 작을수록 제초활성이 작았다. 참비듬의 경우에는 $L_1$상수의 적정값이 3.34 A이므로 이 값에 가까울수록 제초활성이 클 것임을 알 수 있었다. 특히, 2,5-difluoro group 치환체, 6i는 참비듬에 가장 큰 제초활성을 나타내었으나 옥수수에는 가장 작은 제초활성을 미치므로써 현저하게 두 초종간에 선택성을 나타내는 화합물이었다.

• 대한의용생체공학회:의공학회지
• /
• 제36권5호
• /
• pp.191-197
• /
• 2015

Laser acupuncture is defined as the stimulation of traditional acupuncture points with low-intensity, nonthermal laser irradiation. Possible advantages in using laser acupuncture are the noninvasive, painless and low risks of infection treatment. The purpose of this study is to assess the effect of laser acupuncture on the quality and waveform of arterial pulses. Ten acupuncture points were stimulated repeatedly three times in 30 individuals by laser with emission in the near infrared spectral region (808 nm) using an out power and power density of 45 mW and $143W/cm^2$. The analysis of pulse quality and waveform was performed based on the measurement of arterial pressure of the left and right wrist, using a 3-dimensional blood pressure pulse analyzer. Excess-like pulse quality of subjects before laser acupuncture changed significantly to balanced pulse quality after 10, 20, and 30 minutes of laser acupuncture; coefficient of deficient or excess, $C_{DE}$, decreased significantly from 0.68 before acupuncture to 0.61, 0.55, and 0.55 after 10, 20, 30 minutes of laser acupuncture ($$p{\leq_-}0.006$$), respectively. Other pulse qualities, floating or sinking, slow or rapid, choppy or slippery did not change significantly by laser acupuncture (p > 0.05). Pulse waveform analysis showed that amplitude of main peak (systolic function or aortic compliance, $h_1$) of left and right artery pulse waves decreased significantly after 10, 20, and 30 minutes of laser acupuncture (p < 0.05). Other parameters, duration of one cardiac cycle (T), duration of rapid systolic ejection ($T_1$), duration of the systolic phase ($T_4$), and duration of the diastolic phase ($T_5$) of left and right artery pulses did not change significantly after laser acupuncture (p > 0.05).

• Journal of Microbiology and Biotechnology
• /
• 제24권6호
• /
• pp.843-853
• /
• 2014

In the context of artificial groundwater recharge, a reactive soil column at pilot-scale (4.5 m depth and 3 m in diameter) fed by treated wastewater was designed to evaluate soil filtration ability. Here, as a part of this project, the impact of treated wastewater filtration on soil bacterial communities and the soil's biological ability for wastewater treatment as well as the relevance of the use of multi-bioindicators were studied as a function of depth and time. Biomass; bacterial 16S rRNA gene diversity fingerprints; potential nitrifying, denitrifying, and sulfate-reducing activities; and functional gene (amo, nir, nar, and dsr) detection were analyzed to highlight the real and potential microbial activity and diversity within the soil column. These bioindicators show that topsoil (0 to 20 cm depth) was the more active and the more impacted by treated wastewater filtration. Nitrification was the main activity in the pilot. No sulfate-reducing activity or dsr genes were detected during the first 6 months of wastewater application. Denitrification was also absent, but genes of denitrifying bacteria were detected, suggesting that the denitrifying process may occur rapidly if adequate chemical conditions are favored within the soil column. Results also underline that a dry period (20 days without any wastewater supply) significantly impacted soil bacterial diversity, leading to a decrease of enzyme activities and biomass. Finally, our work shows that treated wastewater filtration leads to a modification of the bacterial genetic and functional structures in topsoil.