• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1190-1196
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• 2002

Microwave dielectric properties and multilayer characteristics $(1-x)BiNbO_4-xCaNb_2O_6$ (0${\le}$x${\le}$1.0) ceramics were investigated as a function of $CaNb_2O_6$ content. In the composition range of 0.25${\le}$x${\le}$0.75, the mixture phases of $BiNbO_4$ with stibotantalate structure and $CaNb_2O_6$ with columbite structure were detected and secondary phase or phase transition were not detected. Dielectric constant (K) of $(1-x)BiNbO_4-xCaNb_2O_6$ ceramics was largely dependent on the existing phase and could be estimated by the dielectric mixing rule calculated from maxwell equation. Typically, dielectric constant (K) of 26, quality factor (Qf) of 4300 GHz and Temperature Coefficient of resonant Frequency (TCF) of -18 ppm/${\circ}C$ were obtained for $0.5BiNbO_4-0.5CaNb_2O_6$ specimens with 0.8 wt% $CuV_2O_6$ sintered at 1000${\circ}C$ for 3h. The deviation of X-Y shrinkage and camber value of the multilayers obtained from $0.5BiNbO_4-0.5CaNb_2O_6$ green sheet sintered at 850∼950${\circ}C$ for 20 min. were smaller than those of $BiNbO_4$ multilayers.

• Journal of Korean Society of Forest Science
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• v.66 no.1
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• pp.82-94
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• 1984

The variation of stomatal density and stomatal length of four species of oaks was studied for the purpose of examining the differences among populations and among individual trees within population. Nine populations of Quercus mongolica, four populations of Q. serrata and Q. variabilis respectively, and three populations of Q. acutissima were selected in the natural stands of oaks distributed through the whole country. Twelve leaves were sampled from each of 20 trees from each population. The length of 20 stomata and ten replications of stomatal density were measured from collodion replicas of each leaf under a microscope. Average stomatal densities and lengths ranged through $600-1000/mm^2$ and $19-26{\mu}m$ respectively in all of the species studied. The stomatal densities and lengths presented significant differences statistically at the level of 1 or 5% among populations and among individual trees within population in all the species. Quercus mongolica, especially, showed large variation among populations, while Q. variabilis did very narrow variation compared to the other species. The coefficients of variation of stomatal densities and lengths among individual trees within population exhibited small values of 3.7-12.0% and 1.4-5.3% respectively in all the populations of the species. The average stomatal densities of Q. mongolica showed statistically significant correlation of multiple correlation coefficient of $R_{df{\cdot}2.6}=0.868^*$ and multiple regression equation of $Y=0.041X_1(G.M.T.S.)+0.489X_2(G.M.H.S.)+22.37$ with the sum of growing season mean daily temperature and the sum of growing season mean daily humidity of the stand studied. However the average stomatal lengths showed no relation with the same meteological variables. The figures of frequency distribution of the measurements of leaves or the mean values of individual trees did not show normal distribution curves in some populations. The curves, as well as the results of ANOVA, exhibited the differences among populations.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.877-887
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• 1996

The ideal membranes for membrane-covered oxygen probes system should be selectively permeable for oxygen and chemically inert, and have good mechanical strength. Polysulfone(PSf) was selected to develop the membrane for membrane-covered oxygen electrodes system. PSf membranes have properties such as good reproducibility, good mechanical strength, chemical inertness, and high heat resistance. PSf membranes were cast from polymer solution on the glass plate at constant temperature, and casting solvents used were tetrahydrofuran(THF), methylene chloride, and N-methyl-2-pyrrolidone(NMP). Tricresyl phosphate(TCP) as plasicizer was added to PSf to increase the softness of membrane. The permeation characteristics were observed for pure oxygen and nitrogen through pure PSf membranes by variable volume method and membrane-covered electrode system. The permeability coefficients of oxygen and nitrogen measured by variable volume method were slightly decreased with increasing of upstream pressure. The permeation properties of PSf membrane using methylene choride as casting solvent were not affected by the PSf amount of polymer solution. The permeability coefficients of oxygen and nitrogen for PSf membrane containing TCP were very slightly lower than those for pure PSf membrane, but ideal separation factors were slightly higher. The flexibility of PSf membrane containing 2wt% TCP was better than that of pure PSf membrane. It was expected that this increase in flexibility would solve the difficulty of fixing the membrane to the cathode. The membrane-covered oxygen probes system was composed of anode, cathode and electrolyte. The type of the anode was Ag/AgCl half-cell, that of cathode was Ag, and the electrolyte was 4N KCl solution. The result of sampled current voltametry for PSf membrane showed the plateu region at -0.3V~-1.0V. The correlation coefficient of oxygen partial pressure versus current for PSf membrane was relatively high, 0.99949. It was concluded that PSf membrane was the good candidate for the membrane-covered oxygen probes system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.435-444
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• 2001

Daily time series of longshore wind at 8 stations, sea surface temperature (SST) at 11 stations in the eastern coast of the Korean peninsula during $1983\~1997$ and the NOAA/AVHRR satellite data during $1990\~1998$ were used in order to study the temporal and spatial variations of the upwelling cold water which occurred in the summer season. The cold water occurred frequently in the eastern coastal waters of Korea such as Soimal, Kijang, Ulgi, Kampo, Pohang, Youngduk, Chukbyun, Chumunjin and Sokcho, During the upwelling cold water phenomenon, SST came down more than $-5^{\circ}C$ in a day. The maximum of the averaged RMS amplitude of daily SST was $5.8^{\circ}C$ along the eastern coast of Korea on Julian day 212 from $1983\~1997$. The cross correlation coefficients were higher than 0.5 between Sokcho and Chumunjin in the northern part of the East Sea, and along Soimal, Kijang, Ulgi, Kampo and Pohang in the southern part of the East Sea. In late July, 1995 the cold water occurred at Ulgi coastal area and extended to Ullung island which is located 250 km off the Ulgi coast. Even though the distance between Soimal and the Ulgi coast area is more than 120 km, the cross correlation coefficient related to the anomalies of SST due to upwelling cold water was the highest (0.7) in the southeastern coastal area of the Korean peninsula. This connection may be due to the cyclonic circulation of the Tsushima Current in this area and the topography of the ocean rather than the local south wind which induced the coastal upwelling.

• Journal of the Korean earth science society
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• v.35 no.1
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• pp.1-18
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• 2014

The purpose of this study was to analyze the sensitivity of meteorological fields and the variation of concentration of particulate matters (PMs) due to aerosol schemes and dust options within the WRF-Chem model to estimate Asian dusts affected on 29 May 2008 in the Korean peninsula. The anthropogenic emissions within the model were adopted by the $0.5^{\circ}{\pm}0.5^{\circ}$ RETRO of the global emissions, and the photolysis option was by Fast-J photolysis. Also, three scenarios such as the RADM2 chemical mechanism and MADE/SORGAM aerosol, the MOSAIC 8 section aerosol, and the GOCART dust erosion were simulated for calculating Asian dust emissions. As a result, the scenario of the RADM2 chemical mechanism & MADE/SORGAM aerosol depicted higher concentration than the others' in both Asian dusts and the background concentration of PMs. By comparing of the daily mean of PM10 measured at each air quality monitoring site in Seoul with the scenario results, the correlation coefficient was 0.67, and the root mean square error was $44{\mu}gm^{-3}$. In addition, the air temperature, the wind speed, the planetary boundary layer height, and the outgoing long-wave radiation were simulated under conditions of no chemical option with these three scenarios within the WRF or WRF-Chem model. Both the spatial distributions of the PBL height and the wind speed of u component among the meteorological factors were similar to those of the Asia dusts in range of 1,800-3,000 m and $2-16ms^{-1}$, respectively. And, it was shown that both scenarios of the RADM2 chemical mechanism and MADE/SORGAM aerosol and the GOCART dust erosion were interacted on-line between meteorological factors and Asian dusts or aerosols within the model because the outgoing long-wave radiation was changed to lower than the others.

• Korean Journal of Remote Sensing
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• v.28 no.1
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• pp.69-77
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• 2012

Surface insolation is one of the major indicators for climate research over the Earth system. For the climate research, long-term data and wide range of spatial coverage from the data observed by two or more of satellites of the same orbit are needed. It is important to improve the continuity and consistency of the derived products, such as surface insolation, from different satellites. In this study, surface insolations based on Geostationary Operational Environmental Satellite (GOES-9) and Multi-functional Transport Satellites (MTSAT-1R) were compared during overlap period using physical model of insolation to find ways to improve the consistency and continuity between two satellites through comparison of each channel data and ground observation data. The thermal infrared brightness temperature of two satellites show a relatively good agreement between two satellites : rootmean square error (RMSE)=5.595 Kelvin; Bias=2.065 Kelvin. Whereas, visible channels shown a quite different values, but it distributed similar tendency. And the surface insolations from two satellites are different from the ground observation data. To improve the quality of retrieved insolations, we have reproduced surface insolation of each satellite through adjustment of the Cloud Factor, and the Cloud Factor for GOES-9 satellite is modified based on the analysis result of difference channel data. As a result, the insolations estimated from GOES-9 for cloudy conditions show good agreement with MTSAT-1R and ground observation : RMSE=$83.439W\;m^{-2}$ Bias=$27.296W\;m^{-2}$. The result improved accuracy confirms that the modification of Cloud Factor for GOES-9 can improve the continuity and consistency of the insolations derived from two or more satellites.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.57-73
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• 2008

Nitrate concentrations were measured up to 49 mg/L (as $NO_3$-N) and 22% of the samples exceeded drinking water standard in shallow and bedrock groundwater of the northern Nonsan area. Nitrate concentrations showed a significant difference among land use groups. To predict nitrate concentration in groundwater, multiple regression analysis was carried out using hydrogeologic parameters of soil media, topography and land use which were categorized as several groups, well depth and altitude, and field parameters of temperature, pH, DO and EC. Hydrogeologic parameters were quantified as area proportions of each category within circular buffers centering at wells. Regression was performed to all the combination of variables and the most relevant model was selected based on adjusted coefficient of determination (Adj. $R^2$). Regression using hydrogelogic parameters with varying buffer radii show highest Adj. $R^2$ at 50m and 300m for shallow and bedrock groundwater, respectively. Shallow groundwater has higher Adj. $R^2$ than bedrock groundwater indicating higher susceptibility to hydrogeologic properties of surface environment near the well. Land use and soil media was major explanatory variables for shallow and bedrock groundwater, respectively and residential area was a major variable in both shallow and bedrock groundwater. Regression involving hydrogeologic parameters and field parameters showed that EC, paddy and pH were major variables in shallow groundwater whereas DO, EC and natural area were in bedrock groundwater. Field parameters have much higher explanatory power over the hydrogeologic parameters suggesting field parameters which are routinely measured can provide important information on each well in assessment of nitrate contamination. The most relevant buffer radii can be applied to estimation of travel time of contaminants in surface environment to wells.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.305-311
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• 2016

In cultivation environment, various pesticides are used and some of them could be volatilized into the air. This could affect farmer's health and also cause environmental pollution. This study was carried out to investigate the volatilization of pesticides, and use the reference data for preventing farmer's pesticide intoxication and securing worker safety. The experiment was conducted in a greenhouse using a lysimeter which was of $1m^2$ area and 1.5 m depth filled with upland soil. The pesticides treated in lysimeter soil were ethoprophos (5.0% GR), diazinon (34.0% EC), alachlor (43.7% EC), metolachlor (40.0% EC), chlorpyrifos (2.0% GR), pendimethalin (31.7% EC), carbaryl (50.0% WP), napropamide (50% WP), tebuconazole (25.0% WP) and imidacloprid (2.0% GR). Each pesticide was treated at a concentration of 770.5 mg based on A.I (%). The recovery of pesticide ranged from 77.4 to 99.3%. The volatilized pesticides in air were collected by personal air sampler with PUF tube at 4 l/min flow rate. In addition, temperature and humidity were measured. The collected samples were extracted using acetone in a soxhlet apparatus for 8 hours. The extracted pesticides were resoluted with acetonitrile and diluted 5 times. It was analyzed with LC-MS/MS. For 720 hours experiment, the largest vaporization amount of each pesticide in air was ethoprophos $15.24{\mu}g/m^3$, diazinon $5.14{\mu}g/m^3$, pendimethalin $2.70{\mu}g/m^3$, chlorpyrifos $1.76{\mu}g/m^3$, alachlor $1.40{\mu}g/m^3$, metolachlor $1.12{\mu}g/m^3$, carbaryl $0.27{\mu}g/m^3$, napropamide $0.22{\mu}g/m^3$, tebuconazole $0.11{\mu}g/m^3$ and imidacloprid $0.05{\mu}g/m^3$. The R value (coefficient of correlation) between volatilization and vapor pressure of pesticides is higher than 0.99. Therefore, there is high correlation between volatilization and vapor pressure of pesticides.

• Current Research on Agriculture and Life Sciences
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• v.3
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• pp.36-43
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• 1985

This study was conducted to find out the consumptive use of irrigated water for calculation of a duty of water in paddy rice. Tall statured Japonica rice variety is Jinju(late). Short statured Tongil varities-Taebaek(early) and Pungsan(medium) were planted on the experimental farm of kyungpook National University in 1983. The results obtained in this study were as follows : 1. The average temperature of the underwater surface was $27.1^{\circ}C$ and the maximum was recorded at beginning of the August. 2. The evapotranspiration was gradually increased after transplanting and showed the peak from booting to heading stage of rice varieties. The average evapotranspiration through the whole growing period was 8. 43mm/day(Jinju) for tall statured Japonica variety, and 7.78mm/day(Taebaek), 7.71mm/day(Pungsan) for short statured Tongil varieties. 3. The ratio of evapotranspiration to pan-evaporation through the whole growing period was 1.71 for Japonica variety and 1.55 for Tongil varieties. 4. K-value in Blaney & Criddle formula was 1.41 for Japonica variety and 1.30 for Tongil varieties. Coefficient consumptive use of water (Kc-value) was 1.40 for Japonica variety and 1.27 for Tongil varieties. 5. It appeared that the water consumption in the 6, 8 cm pot is more than that of 2, 4 cm pot but the number of panicle of the 6, 8 cm pot is somewhat less than that of 2, 4 cm pot. The deeper water level is the less tiller became. It is consindered that 2 cm pot is more profitable than the others.

• The Korean Journal of Pesticide Science
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• v.17 no.2
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• pp.94-106
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• 2013

The proficiency testing for the residue laboratories of pesticide registration was conducted in order to improve the reliability and the ability for pesticide residue analysis. On October 2011 the testing was carried out using the soil collected and kept as the moistened state for five years, which is expected to very low residue levels of pesticides. The soil was fortified with chlorpyrifos, metolachlor and procymidone in a manner similar to prepare soil sample for indoor soil degradation test, and then sub-samples were prepared for the distribution to participants. Some of them were randomly selected for confirm of homogeneity and to ensure the stability of samples at room temperature. Samples were consisted of two soil treated as different levels, one of which was used to the assesment and another used to confirm. In addition, provide three standard solutions, respectively concentration of 10 mg/L, and untreated soil. Forty seven institutions submitted results. The medians of results were used as the assigned values for pesticide residues. Fitness for purpose standard deviation of proficiency test was calculated by applying 20% RSD as the coefficient of variation allowed in the soil residue test. Z-score was applied for evaluation of individual pesticides, and the average of the absolute value of the Z-score for the overall assessment of pesticides. Laboratories evaluated the absolute value of the Z-score less than 2 to fit the case of chlorpyrifos and procymidone were 44, metolachlor 40.