• Journal of Life Science
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• v.20 no.7
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• pp.1127-1133
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• 2010

The total photosynthetic rate in leaf mustard lines, which was calculated as the sum of the photosynthetic rate and the respiration rate, was not significantly different from their photosynthetic rate. Plant height, standing of rosetteness, showed a similar change to its specific leaf area (SLA). With increasing the plant height, leaf density increased and leaf color was lighter. It was found that shoot dry weight of leaf mustard was more affected by respiration. Also, it was hypothesized that respiration occurred not only in the leaf but also the stem. It was found that mustard lines whose leaf density was low showed a higher shoot growth. From this result, it was concluded that selection of a leaf mustard line with a larger SLA and lower leaf thickness could be effective in increasing photosynthetic rate.

• Journal of The Korean Astronomical Society
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• v.34 no.1
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• pp.25-29
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• 2001

We have constructed a non-spherical model for the hot oxygen corona of Mars by including the effects of planetary rotation and diurnal variation of the Martian ionosphere. Exospheric oxygen densities are calculated by integrating ensemble of ballistic and escaping oxygen atoms from the exobase over the entire planet. The hot oxygen atoms are produced by dissociative recombination of $O^+_2$, the major ion in the Martian ionosphere. The densities of hot oxygen atoms at the exobase are estimated from electron densities which have been measured to vary with solar zenith angle. Our model shows that the density difference of hot oxygen atoms between noon and terminator is about two orders of magnitude near the exobase, but reduces abruptly around altitudes of 2000 km due to lateral transport. The diurnal variation of hot oxygen densities remains significant up to the altitude of 10000 km. The diurnal variation of the hot oxygen corona should thus be considered when the upcoming Nozomi measurements are analyzed. The non-spherical model of the hot oxy-gen corona may contribute to building sophisticate solar wind interaction models and thus result in more accurate escaping rate of oxygens from Mars.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.57-57
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• 2009

In this work, we carried out the variation of surface characteristics of organic polymer films by O2 plasma. The plasma diagnostics were performed by DLP(Double Langmuir Probe) and OES(Optical Emission Spectroscopy) measurements. Moreover, variation of surface characteristics were measured by AFM(Atomic Force Microscope), XPS(X-ray Photoelectron Spectroscopy), and contact angle goniometer. It was found that the etch rate of organic films was controlled by O radicals flux and dc bias voltage. And O radical density and dc bias voltage increased with increasing bias power. So, it was changed surface energy as a function of surface roughness and O/C ratio in organic films.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.67-69
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• 2004

ZnO varistor ceramics which were fabricated with variation of added of 0.01, 0.02, 0.03, 0.05, 0.1mol% $Nb_2O_5$ sintered at $1150^{\circ}C$. In the specimen added 0.05mol% $Nb_2O_5$, sintered density was $5.87g/cm^3$ and electrical properties were superior to any other components. The nonlinear coefficient was 75, and clamping voltage ratio was 1.40. And, endurance surge current in the specimen added 0.05mol% $Nb_2O_5$ was $6500A/cm^2$, and deviation of varistor voltage was -1.7%. As P.C.T and T.C.T environment test were succeed in all specimens, and deviation of varistor voltage in the specimen added 0.3mol% $Nb_2O_5$ was -0.81%. All specimens showed a good leakage current property in the High Temperature Continuous Load Test for 1000hr, at $85^{\circ}C$, and variation rate of the varistor voltage was -1.71%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1186-1191
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• 2004

ZnO varistor ceramics which were fabricated with variation of added of 0.5～1.0 mol% Co$_3$O$_4$, were sintered at 1150 $^{\circ}C$. In the specimen added 0.7 mol% Co$_3$O$_4$, sintered density was 6.03 g/㎤ and electrical properties were superior to any other compositions. The nonlinear coefficient a and clamping voltage ratio were 83 and 1.35, respectively. But, endurance surge current in the specimen added 0.5 mol% Co$_3$O$_4$ was 7000 A/$\textrm{cm}^2$, and deviation of varistor voltage was Δ-3.23 %. As P.C.T and T.C.T environmental test were succeed in all specimens, and deviation of varistor voltage in the specimen added 0.6 mol% Co$_3$O$_4$ was Δ-0.81 %. All specimens showed good leakage current property on the High Temperature Continuous Load Test(HTCLT) for 1000 hr at 85 $^{\circ}C$ and variation rate of the varistor voltage below Δ-2.0 %.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.201-207
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• 2017

An electron-excited temperature ($T_{ex}$) is not determined by the Boltzmann plots only with the spectral data of $4p{\rightarrow}4s$ in an Ar-plasma jet operated with a low frequency of several tens of kHz and the low voltage of a few kV, while $T_{ex}$ can be obtained at least with the presence of a high energy-level transition ($5p{\rightarrow}4s$) in the high-voltage operation of 8 kV. The optical intensities of most spectra that are measured according to the voltage and the measuring position of the plasma column increase or decay exponentially at the same rate as that of the intensity variation; therefore, the excitation temperature is estimated by comparing the relative optical-intensity to that of a high voltage. In the low-voltage range of an Ar-jet operation, the electron-excitation temperature is estimated as being from 0.61 eV to 0.67 eV, and the corresponding radical density of the Ar-4p state is in the order of $10^{10}{\sim}10^{11}cm^{-3}$. The variation of the excitation temperature is almost linear in relation to the operation voltage and the position of the plasma plume, meaning that the variation rates of the electron-excitation temperature are 0.03 eV/kV for the voltage and 0.075 eV/cm along the plasma plume.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.1
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• pp.18-24
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• 1989

The effect of soil physico-chemical properties of pre and post soil preparation and permanent bed period on growth and yield was analysed by two models of annual variation and percent annual change (PAC). 1. Aggregation, porosity, bulk density except moisture were significantly different in each year from preparation to the 6th year while all soil chemical properties except Mg were significantly different in each year. 2. Soil physical properties showed significant simple correlation with yield and negative with the missing plant rate in each year while the electroconductivity ($EC_5$) of the 4th year showed significant correlation with yield. 3. Yield showed significant positive correlation with the variation of aggregation in permanent bed period, and negative with variation and PAC of aggregation of preplanting soil and variation of moisture in permanent bed period. Missing plant rate was negatively correlated with porosity variation of preplanting soil and positively with PAC of aggregation in preplanting soil and of moisture in permanent bed period. 4. According to multiple regression between yield and soil physical properties, porosity of preplanting soil was in the greatest contribution. Among aggregations, the variation in permanent bed period was in the greatest contribution.

• KSBB Journal
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• v.11 no.3
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• pp.303-310
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• 1996

The marine microalga Isochrysis galbana Parke was studied to optimize its growth conditions in flask culture. Important medium components studied include nitrogen source, buffer, trace elements and vitamins. Environmental conditions include pH, temperature, light intensity, mixing extent and working volume. The medium prepared from natural sea-waters gave a higher final cell density than the medium prepared from synthetic sea-water Nitrate was a better source than ammonium. In the range of 0.4∼2mM, the final cell density was proportional to the initial nitrate concentration and the cell yield was estimated to be 8.5g dry cell wt/g N. For phosphate, optimal growth was observed in 0.1∼1.0mM but a considerable variation in pH was resulted. The addition of Tris at 5mM or 7mM could stabilize the medium pH, but this significantly reduced both growth rate and final cell density, The effect of trace elements and vitamins was negligible. Optimal temperature and initial pH were $20^{\circ}C$ and 8. When the intensity of incident light was varied in the range of 400∼2100 lux, the growth rate increased from 10mL to 70mL, the final cell density decreased although the initial growth rate did not change. Optimal agitation speed was 100rpm when working volume was 30mL. With optimal conditions, the maximum specific growth rate obtained was 0.021hr-1 and the final cell density was 1.1g/L.

• The Transactions of the Korea Information Processing Society
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• v.7 no.7
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• pp.2246-2253
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• 2000

In this paper, we show that one can enhance the performance of blind segmentation of phoneme boundaries by adopting the knowledge of Korean syllabic structure and the regions of voiced/unvoiced sounds. eh proposed method consists of three processes : the process to extract candidate phoneme boundaries, the process to detect boundaries of voiced/unvoiced sounds, and the process to select final phoneme boundaries. The candidate phoneme boudaries are extracted by clustering method based on similarity between two adjacent clusters. The employed similarity measure in this a process is the ratio of the probability density of adjacent clusters. To detect he boundaries of voiced/unvoiced sounds, we first compute the power density spectrum of speech signal in 0∼400 Hz frequency band. Then the points where this paper density spectrum variation is greater than the threshold are chosen as the boundaries of voiced/unvoiced sounds. The final phoneme boundaries consist of all the candidate phoneme boundaries in voiced region and limited number of candidate phoneme boundaries in unvoiced region. The experimental result showed about 40% decrease of insertion rate compared to the blind segmentation method we adopted.

• Journal of the Korean Society for Heat Treatment
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• v.23 no.3
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• pp.131-136
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• 2010

The LCF (low cycle fatigue) behavior and the serration phenomena in the plastically deformed and non-deformed 5052 Al alloy were investigated. The plastic deformation was performed by 1 pass or 4 passes in ECAP (equal channel angular pressing) followed by annealing. Only cyclic hardening continued from the beginning until fracture at all strain amplitudes during LCF in the non-deformed alloy, which was caused by the increase in dislocation density during fatigue. Slight cyclic hardening followed by plateau until fracture was observed during LCF in the ECAPed alloy, which was caused by the slight increase in dislocation density in the beginning and then keeping constant in dislocation density afterward until fracture by forming subgrains in this stage of fatigue. The serrations on the stress-strain curves of this alloy were observed, which indicate that the dynamic strain aging (DSA) is occurring during plastic deformation. The variation in amplitudes of serration was studied by changing the strain rate in tensile or fatigue tests.