• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.2
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• pp.63-77
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• 2022

Our aim was to reduce estimation errors of a wind velocity model used as an early warning system for weather risk management in the agricultural sector. The Rural Development Administration (RDA) agricultural weather observation network's wind velocity data and its corresponding estimated data from January to December 2020 were used to calculate linear regression equations (Y = aX + b). In each linear regression, the wind estimation error at 87 points and eight time slots per day (00:00, 03:00, 06:00, 09.00, 12.00, 15.00, 18.00, and 21:00) is the dependent variable (Y), while the estimated wind velocity is the independent variable (X). When the correlation coefficient exceeded 0.5, the regression equation was used as the wind velocity correction equation. In contrast, when the correlation coefficient was less than 0.5, the mean error (ME) at the corresponding points and time slots was substituted as the correction value instead of the regression equation. To enable the use of wind velocity model at a national scale, a distribution map with a grid resolution of 250 m was created. This objective was achieved b y performing a spatial interpolation with an inverse distance weighted (IDW) technique using the regression coefficients (a and b), the correlation coefficient (R), and the ME values for the 87 points and eight time slots. Interpolated grid values for 13 weather observation points in rural areas were then extracted. The wind velocity estimation errors for 13 points from January to December 2019 were corrected and compared with the system's values. After correction, the mean ME of the wind velocities reduced from 0.68 m/s to 0.45 m/s, while the mean RMSE reduced from 1.30 m/s to 1.05 m/s. In conclusion, the system's wind velocities were overestimated across all time slots; however, after the correction model was applied, the overestimation reduced in all time slots, except for 15:00. The ME and RMSE improved b y 33% and 19.2%, respectively. In our system, the warning for wind damage risk to crops is driven by the daily maximum wind speed derived from the daily mean wind speed obtained eight times per day. This approach is expected to reduce false alarms within the context of strong wind risk, by reducing the overestimation of wind velocities.

• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.1
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• pp.2853-2877
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• 1973

Models of cross-sections and channels were made in order to measure seepage losses. Cross-sections were made of sand, sandy clay loam and loam, their thicknesses being 30cm and 40cm, respectively. Flow depths kept in the cross-sections were 4cm, 6cm, 8cm and 10cm. Straight and curved channel models were provided so as to measure seepage losses, when constant water depths maintained at the heads of the channels were 7.3cm and 5.7cm, respectively. The results obtained in this experiment are presented as follows: 1) A cumulative seepage loss per unit length at a point in the channel varies in accordance with time and flow depth. The general equation of cumulative seepage loss may be as follows(Ref. to Table V.25): $$q_{cum}=\int_{o}^aq(a)dt+\int_a^bq(b)dt+\int_b^tq(c)dt$$ 2) In case that the variation of water depth through the channel is slight, the total seepage loss may be computed by applying the following general equation: $$\={q}_{cum}{\cdot}x=\int_o^tq_{cum}\frac{{\partial}x}{{\partial}t}dt$$ 3) Because seepage loss varies considerably according to water depth in case that the variation of flow depth through the channel is great, seepage loss should be computed by taking account of the change of flow depth. 4) The relation between time and traveling distance of water flow may be presented as the following general equation(Ref. to Table V.29): $$x=pt^r$$ 5) The ratios of the seepage losses of the straight channel to the curved channel are 1:1.03 for a flow depth of 7.3cm and 1:1.068 for that of 5.7cm. 6) The ratios of the seepage losses occurring through the bottom to those through the inclined plane in the channel cross-section are 1:2.24 for a water depth of 8cm and 1:2.47 for a depth of 10cm in case that soil-layer is 30cm in thickness. Similarly, those ratios are 1:2.62 and 1:2.93 in case of a soil-layer thickness of 40cm(Ref. to Table V.5).

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.981-984
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• 1995

New diamineplatinum(Ⅱ) complexes of cyclohexylidenemalonate (chm) ligand, A2Pt(OOC)2C=C(CH2)4CH2 (1, A2=ethylenediamine (en); 2, A2=propylenediamine (pn); 3, A=NH3; 4, A=isopropylamine (ipa)) have been prepared. Their oxidation with H2O2 has led to the corresponding dihydroxoplatinum(Ⅳ) complexes: cis, cis, trans-A2Pt((OOC)2C=C(CH2)4CH2)(OH)2 (5, A2=en; 6, A2=pn; 7, A=NH3; 8, A=ipa). The title complexes have been characterized by means of various spectroscopies and X-ray crystallography. 5 crystallizes in the monoclinic space group P21/a (Z=4) with a=12.098(7) Å, b=9.552(2) Å, c=16.258(4) Å, β=98.03(5)° and V=1860(1) Å3. The structure was refined to R=0.074. The local geometry around platinum atom is approximately octahedral with each hydroxide group in trans position. These platinum complexes are stable in aqueous solution. Pt(Ⅳ) complexes are readily reduced to the corresponding Pt(Ⅱ) complexes by ascorbic acid.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.2
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• pp.73-77
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• 2024

The spinel-type oxide (Ni_x, Mn_y, Co_3-x-y)O₄ (NMC) is widely utilized as a material for temperature sensors with a negative temperature coefficient (NTC), finding applications across various industries including electric vehicle battery management systems. Typically, NMC is manufactured using solid-state reaction methods employing powders of Ni, Mn, and Co compounds, with the densification process through sintering recognized as a crucial factor determining the electrical properties of the temperature sensor material. In this study, NMC pellets were synthesized via solid-state reaction and their crystallographic and microstructural characteristics were investigated. Also, the activation energy for densification behavior during the sintering process was determined. According to the analysis results, the room temperature resistance of the NMC pellets was measured at 10.03 Kohm, with the sensitivity parameter, B-value, recorded at 3601.8 K, indicating their potential applicability as temperature sensors across various industrial fields. Furthermore, the activation energy for densification was found to be 273.3 ± 0.4 kJ/mol, providing valuable insights into the thermodynamic aspects of the sintering process of the NMC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.558-566
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• 2003

We fabricated thick film monopole antennas using Li-doped BiNbO$_4$ ceramics and investigated their electrical properties as a function of the Li-doping concentration. Compared with undoped BiNbO$_4$ ceramics, addition of Li$_2$CO$_3$ improved dielectric constant by increasing of ionic polarization, but reduced quality value by increasing of lattice distortion. Antenna properties like gain, bandwidth and radiation patterns were also greatly affected by the addition of Li$_2$CO$_3$. With increasing amount of Li$_2$CO$_3$, the bandwidth of ceramic monopole antenna was increased to 81.7 %, but the gain was reduced to -10.03 dBi. Also radiation patterns were so distorted and showed low dB value by increasing of dielectric loss.

• Journal of the Korean Ceramic Society
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• v.49 no.1
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• pp.84-89
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• 2012

Attempts were made to develop a stable gray pigment at reducing atmosphere, substituting Ti in $ZrTiO_4$ with Mn, Fe, Co and Cu The pigment synthesized at $1300~1500^{\circ}C$ by solid state method with the composition of $ZrTi_{1-x-y}A_xB_yO_4$ (x = y = 0.005, 0.015, 0.035, 0.055, 0.075, 0.095, 0.115, 0.135, 0.155, 0.175 and 0.195 mole, A = Mn(III), Fe(III), Co(II, III) and Cu(II) (chromophores), B = Sb (counterion). The pigments were fired at $1400^{\circ}C$ for 3 h with substitute amount changes of Mn, Fe, Co and Cu to $ZrTiO_4$ crystals, and analyzed by Raman spectroscopy to figure out substitute limits. Results indicated 0.035 mole for Mn, 0.115 mole for Fe, 0.015 mole for Co and 0.015 mole for Cu as substitute limits, respectively. Figs. 1, 2, 3, and 4 represent each substitute pigments of Mn, Fe, Co and Cu. Synthesized pigment was applied to a lime and a lime-magnesia glaze at 7 wt% each, and fired at reducing atmosphere of $1240^{\circ}C$, soaking time 1h. Gray color was obtained with CIE-$L^*a^*b^*$ values at 44.55, -0.65, 1.19(Mn), 40.36, -0.90, 0.30(Fe), 42.63, -0.03, -1.49(Cu) and -40.79, -0.28, -0.91(Co), respectively.

• Food Science and Preservation
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• v.19 no.4
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• pp.532-538
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• 2012

Seven rice varieties (Dasan, Keunseon, Goami, Baekjinju, Seolgaeng, Hangangchal and Heukseol) were used to study the physicochemical properties of dry milled (200-mesh) rice flour species. The moisture and crude protein contents of rice were 15.00-15.10% and 6.09-8.21%, respectively. The crude lipid and crude ash of rice were 0.21-1.02% and 0.37-1.62%, respectively. As for the Hunter's color value, the L value was highest in the Dasan flour (96.47); the a value was highest in the Heukseol flour (5.03); and the b value was highest in the Baekjinju flour (3.36). The water aborption index was highest in the Goami flour (1.45), and the water solubility index was highest in the Hangangchal flour (9.16%). The amylose contents of the rice flour species were highest in the Goami (26.42%) rice flour, followed by the Dasan (19.39%), Seolgaeng (19.24%), Keunseon (18.06%), Heukseol (15.52%), Baekjinju (9.16%), and Hangangchal (0.84%) rice flour. In the X-raydiffractin patterns of the diverse species, seven tice varieties showed A-type crystallinity. As for the amylogram properties, the initial pasting temperature was 58.00-$69.03^{\circ}C$. The maximum viscosity was highest in the Dasan flour. The Heukseol flour had the lowest maximum viscosity, breakdown, and setback. In terms of the thermal properties of the differential scanning calorimeter (DSC), the onset temperature was 59.03-$66.84^{\circ}C$; the peak temperature, 66-70-$72.82^{\circ}C$; and the end temperature, 74.06-$78.66^{\circ}C$. The enthalpy (${\Delta}H$) was lowest in the Heukseol flour (7.59 J/g) and highest in the Seolgaeng flour (11.36J/g).

• Economic and Environmental Geology
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• v.26 no.2
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• pp.129-134
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• 1993

At the Janggun mine, boulangerite usually occurs as needles or irregularly-shaped grains, up to $500{{\mu}m}$ in longer dimensions, closely associated with galena, minerals of a tetrahedrite-freibergite series and bournonite in the peripheries of South A and B orebodies and the zone of manganoan carbonates surrounding them. In some places, especially at the top of South B orebody, it occures as "feather ore" consisting of its fine needles or "hairs" in small drusy cavities together with fine-grained euhedral galena, pyrite, manganoan carbonates, quartz, etc. In reflected light, it is bluish grey in colour exhibiting moderate bireflectance and is strongly anisotropic without any internal reflections. Reflectance in air is $R_{max}=43.2$, $R_{min}=35.7$ percent at wavelength of 580 nm, and VHN: $146-173\;kg/mm^2$ at a 50 g-load. The chemical composition on the average from 23 complete spot analyses by electron microprobe is, Pb 56.1, Sb 25.1, S 18.5, Total 99.6 (all in weight percent); the corresponding chemical formula calculated on the basis of S=11 is; $Pb_{5.16}Sb_{3.93}S_{11.0}$ which fulfils approximately the ideal formula $Pb_5Sb_4S_{11}$. The strongest reflections on the X-ray diffraction pattern are; $3.73\;{\AA}\;(10)$, $3.22\;{\AA}\;(5)$, $3.03\;{\AA}\;(4)$ and $2.82\;{\AA}\;(5)$ and the pattern is in harmonic with space group $C^5_{2h}-P2_1/a$. From the textural evidence of the microscopic observations, the mineral is considered to have been formed at the latest stage of hydrothermal lead-zinc-silver mineralization.

• Korean Journal of Metals and Materials
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• v.49 no.4
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• pp.348-354
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• 2011

Long-lasting brightness $Sr_{4}Al_{14}O_{25}$ : $Eu^{2+}$, $Dy^{3+}$, $Ag^{+}$ phosphor was synthesized by modified solid state reaction and its photoluminescence was investigated. $Sr(NO_3)_{2}$ and $Al(NO_3)_3{\cdot}9H_{2}O$ as starting materials, and $B_{2}O_{3}$ as a flux were mixed with $Eu_{2}O_{3}$ as an activator, $Dy_{2}O_{3}$ as a coactivator, and $AgNO_{3}$ as a charge compensator. The crystalline of target powder showed a single-phase $Sr_{4}Al_{14}O_{25}$ by the XRD characterization and the average particle size was about 20-30 ${\mu}m$ from the FE-SEM observation. $Ag^{+}$ ion doping effects (0-0.06 mol) on $Sr_{4}Al_{14}O_{25}:Eu^{2+},\;Dy^{3+},\;Ag^{+}$ phosphor were measured by photoluminescence spectrometer and luminescence meter. The of photoluminescence intensity of the $Sr_{3.64}Al_{14}O_{25}:Eu_{0.11},\;Dy_{0.22},\;Ag_{0.03}$ phosphor was higher than other compositions and afterglow brightness was 0.186 $cd/m^{2}$.

• Journal of Korean Society of Forest Science
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• v.1 no.1
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• pp.7-11
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• 1962

1. The inflorescence of the oak has been evolved through a serial reduction of the panicle as is presented in the figure 1. 2. Perianth lobes though they range from one to twelve in a flower six loves occur more than 50% of tested flowers as is tabulated in the table 1. They have been increased partly by a fusion of flowers and partly by a reversion of the stamen into the perianth lobe. They also have been decreased by a fusion of perianth lobes each other. 3. Stamen numbers in a flower range from one to twenty four, but eight stamens are more common than the others as is shown in the table 1. They have been increased by a fusion of flowers and decreased by a fusion of stamens in a flower as are presented in the figure 4. 4. Floral position in the inflorescence, environmental factors, hybridity, and abnormal nutrition supply seem to accelerate fusion and reduction of the stamen in a flower. 5. Flowers which consist of eight stamens and six perianth lobes occur more common than the others, however, the number of the stamen (Y) and the perianth lobes (X) appear to be correlated as follows (see also fig.5.). Y=1.09X+3.78, r=0.4 for Q. dentate Thumb. (7004 flowers investigated) Y=0.71X+4.18, r=0.48 for Q. mongolica Fischer (7409 flowers investigated) Y=1.03X+2.91, r=0.4 for Q. allena B1. (8662 flowers investigated) Y=0.69X+2.00, r=0.4 for Q. serrata Thumb. (9048 flowers investigated) 6. Morphological similarity of the bracteoles and perianth lobes as illustrated in the fig. 3, phenomena of a fusion of bracteoles and separation of perianth lobes into three groups in a flower, and increasing and decreasing phenomena of the stamen number and perianth lobes in a flower as presented in the figures 3 and 4 support the proposal on the oak flower evolution made by H. Hjelmquist in 1948.