• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.290-297
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• 2014

BACKGROUND: The current study purposed to analyse the dissipation levels of a neonicotinoid insecticide and clothianidin in paddy and upland soils and clarify the effects of soil moisture on degradation and persistence of the insecticide. METHODS AND RESULTS: In order to achieve the research purposes, clothianidin 8% SG was applied to the paddy and upland fields at the rate of 0.024 kg a.i./10a, while the analytical standard was treated at 0.25 mg/kg soil under laboratory conditions. Based on the multiple first-order kinetics, total clothianidin in soils was dissipated with $DT_{50}$ of 6.7-16.1 and 6.9-8.2 days in the paddy and upland fields, respectively, whereas the figures under the laboratory condition became larger showing 56.3 and 19.6 days. CONCLUSION: As affected by soil moisture, some differences in degradative pathways were observed. Flooding of soil caused evidently demethylation and delayed cyclization of a major metabolite, thiazolylmethylguanidine (TMG) and methylaminoimidazole(MAI), compared to the aerobic upland condition. More than 80% and 50% of the parent compound was dissipated by the 24th day after the final application in both soils and, transformation products had constituted most of soil residues after that.

• Journal of the Korean Society of Radiology
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• v.14 no.3
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• pp.193-201
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• 2020

The purpose of this study is to evaluate the photon characteristics according to the material and thickness of the electrons incidented through a linear accelerator. The computer simulation design is a linear accelerator target consisting of a 2 mm thick tungsten single material and a 1.8 mm and 2.3 mm thick tungsten and copper composite material. In the research method, First, the behavior of primary particles in the target was evaluated by electron fluence and electron energy deposition. Second, photons occurring within the target were evaluated by photon fluence. Finally, the photon angle-energy distribution at a distance of 1 m from the target was evaluated by photon fluence. As a result, first, electrons, which are primary particles, were not released out of the target for electron fluence and energy deposition in the target of a single material and a composite material. Then, electrons were linearly attenuated negatively according to the target thickness. Second, it was found that the composite material target had a higher photon generation than the single material target. This confirmed that the material composition and thickness influences photon production. Finally, photon fluence according to the angular distribution required for shielding analysis was calculated. These results confirmed that the photon generation rate differed depending on the material and thickness of the linear accelerator target. Therefore, this study is necessary for designing and operating a linear accelerator use facility for container security screening that is being introduced in the country. In addition, it is thought that it can be used as basic data for radiation protection.

• Journal of the Korean Chemical Society
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• v.47 no.3
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• pp.220-228
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• 2003

This study was to examine the thermodynamic features of polyelecrolytic adsorption of polyamidoamine-epichlorohydrin(PAE) in a papermaking wet-end. The PAE adsorption experiments were conducted in a stirred jar containing an aqueous fibrous suspension and evaluated in terms of Langmuir and Freundlich parameters. The electrokinetic property of a stock was examined by measuring the zeta potential of each colloidal suspension. The polyelectrolytic PCD titration was employed to determine the adsorbed amounts of PAE polymer. The zeta potential of a stock, being varied significantly depending upon the addition of PAE polymer, showed initially a sharp increase and later an exponential decay as a function of time . The PAE adsorption exhibited a pseudo-Langmuir adsorption behavior at$20^{\circ}C$ , whereas its Freundlich power(v) increased in a proportional way at an elevated temperature. The train numbers calculated on the basis of adsorption thermodynamics were 7 to 8. The length of the extended loop of PAE was calculated as 215 nm at $20^{\circ}C$ and increased at a rate of 9% at every $10^{\circ}C$ rise in temperature. The PAE adsorption was proven to be an exothermic physisorption with the estimated adsorption enthalpy of -27 to -29 kJ/mol.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.4
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• pp.311-318
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• 2004

It is very important for the safe navigation and fishing operation to ensure the hull response of a fishing vessel in rough seas. This is an experimental study on the dynamical characteristics of ship's motion during operating job and sailing in the real sea. The experiments were carried out on the small stern trawler in operating job and sailing, and then the ship's roll and pitch motion were simultaneously recorded by P/C according to the wave directions. From these data, the statistical properties and power spectra were obtained and the analysis of ship's motions in the both case were made. The results obtained are summarized follows : (1) The amplitudes of pitch motion don't appear a big different between trawl job and sailing, but at bow seas, its in sailing have a tendency to increase more than in trawl job. The amplitudes of roll motion appear a bog different between trawl job and sailing, but at beam sea, that slightly decreasing tendency. (2) The peak period of pitch motion in trawl job and sailing change, but that of roll motion don't change according to the direction of waves. (3) The warp tention cause the motion of hull to be reduce, if the tention of each side have a ballance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.1
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• pp.39-46
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• 2015

In this paper, a gas sensor using a modified $90^{\circ}$ hybrid coupler structure with conducting polymer which operates at 2.4 GHz is represented. Conducting polymers are used to the gas sensing material in proposed sensors. The conducting polymer varies its electrical property, such as work function and conductivity corresponding to the certain gas. To verify this variation of electrical property of conducting polymer at microwave frequencies, the conducting polymer is incorporated with the $90^{\circ}$ hybrid coupler structure, and this proposed sensor operates as reflection type variable attenuator and variable phase shifter. The conducting polymer is employed as impedence-variable transmission lines that cause a impedance mismatching between the general transmission line and conducting polymer. The experiment was conducted with 100 ppm ethanol gas at temperature of $28^{\circ}C$ and relative humidity of 85 %. As a result, the amplitude deviation of $S_{21}$ is 0.13 dB and the frequency satisfying ${\angle}S_{21}=360^{\circ}$ is shifted about 2.875 MHz.

• Journal of Applied Biological Chemistry
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• v.63 no.3
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• pp.267-274
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• 2020

The dissipation characteristics and kinetics of fungicide mandipropamid and insecticide thiamethoxam in lettuce under greenhouse conditions were investigated at three different lettuce-growing fields for estimating the pre-harvest residue limits (PHRLs). The analytical methods were fully validated for the quantitation of pesticide residues using High-Performance Liquid Chromatography-Photo Diode Array detector or Ultraviolet-Visible Detector and applied to real samples. The lettuces suitable for shipment were harvested during 10 days including pre-harvest interval after treatment at the recommended dose by safe-use guidelines. The initial mean residues in different fields were 6.68-17.87 and 4.96-8.31 mg/kg for mandipropamid and thiamethoxam, respectively, which decreased to 16-54 and 14-44% in 10 days. The clothianidin, a metabolite of thiamethoxam, was detected in <0.02 to 0.37 mg/kg. The dissipation of both pesticides followed first-order kinetics over a period of 10 days after application. Based on the residue data, the mean dissipation rate constant (λ) and biological half-lives (T_1/2) were estimated to be -0.1060 and 6.5 days of mandipropamid and -0.1236 and 5.6 days of thiamethoxam. The PHRLs for lettuce on the 10th and 5th day before harvesting were calculated to be 63.24 and 43.56 mg/kg for mandipropamid, and 44.66 and 25.88 mg/kg for thiamethoxam, with -0.0746 and -0.1091 of the upper 95% confidence intervals of dissipation rate constant, respectively. This work would be useful as guidance for adjusting the shipment date and contribute to stabilizing the income of farmers in Korea.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.6
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• pp.25-34
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• 2012

New calibration method for the near-field scanning (NFS) system is presented. The proposed calibration method consisted of a new near-field antenna (NFP) and newly devised patterns as circular patch patterns (CPPs) and meander patterns (MPs). The proposed patterns were used for improving spatial resolutions and simplifying a calibration procedure of the NFP compared to the conventional method defined in the IEC61967-3 and 6. Also, the effect of the length of NFPs on attenuation characteristics was investigated with length of 8mm and 30mm. For them, we designed and fabricated CPPs of diameter (D) = 20, 40, 60, and 100mm and MPs of various widths and spaces. We found the reverse relations between spatial resolutions and heights of measuring points by using simplified calibration procedure. The testing result shows that the spatial resolution of $120{\mu}m$ at height of $200{\mu}m$ was verified without complex correlation algorithms under 8GHz. For manufacturing cost all patterns and the NFP were realized with low-cost fabrication using PCB (FR-4) not by a conventional LTCC process. For verification of chip-level EMC from the results, near-field scanning system (NFSS) having step resolution of Sub-micron scale was produced and by using the proposed NFSS and proposed NFP measurement of chip shows accurately the shape of the resolution of $200{\mu}m$ patterns for securing a high level of chip-level EMC verification.

• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1175-1188
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• 2015

The Ministry of Education of Korea announced the university structural reform plans which reduces 160,000 of the university entrance quota during 10 years from January 2014. Because the reduction plans of entrance quota influence regional economy as well as students and universities, naive evidence of the Ministry of Education of Korea is disappointed. In this research, we forecast the total number of the university entrance exam candidate by 2032 including not only third grade high school students but also repeaters according to the 16 metropolises and provinces in Korea. We also forecast the regional university recruiting rate using the forecasts of the total number of the university entrance exam candidates. However, we can not make more realistic results because we can not apply the inter-regional movement of students to the forecast. In order to handle this limitation, we first estimated the rank of the whole 7,277 departments of all universities in Korea and assigned the quotas according to the estimated rank for each departments and then we calculated the local university recruiting rate. The estimated the university recruiting rates of 16 metropolises and provinces can provide more noticeable results of characteristics and problems than that of nationwide.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.799-804
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• 2016

Broadband powerline communication (BPLC) uses distribution lines as a medium for achieving effective bidirectional data communication along with electric current flow. As the material characteristics of power lines are not good at the communication channel, the development of power line communication (PLC) systems for internet, voice, and data services requires measurement-based models of the transfer characteristics of the network suitable for performance analysis by simulation. In this paper, an analytic model describing a complex transfer function is presented to obtain the attenuation and path parameters for a multipath power line model. The calculated results demonstrated frequency-selective fading in multipath channels and signal attenuation with frequency, and were in good agreement with the experimental results. Inductive coupling units are used as couplers for coupling the signal to the power line to avoid physical connections to the distribution line. The inductance of the ferrite core, which depends on the frequency, determines the cut-off frequency of the inductive coupler. Coupling loss can be minimized by increasing the number of windings around the coupler. Coupling efficiency was improved by more than 6 dB with three windings compared to the results obtained with one winding.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.19-33
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• 2018

This study proposed a rainfall-runoff model for the purpose of real-time flood warning in urban basins. The proposed model was based on the shot noise process, which is expressed as a sum of shot noises determined independently with the peak value, decay parameter and time delay of each sub-basin. The proposed model was different from other rainfall-runoff models from the point that the runoff from each sub-basin reaches the basin outlet independently. The model parameters can be easily determined by the empirical formulas for the concentration time and storage coefficient of a basin and those of the pipe flow. The proposed model was applied to the total of three rainfall events observed at the Jungdong, Guro 1 and Daerim 2 pumping stations to evaluate its applicability. Summarizing the results is as follows. (1) The unit response function of the proposed model, different from other rainfall-runoff models, has the same shape regardless of the rainfall duration. (2) The proposed model shows a convergent shape as the calculation time interval becomes smaller. As the proposed model was proposed to be applied to urban basins, one-minute of calculation time interval would be most appropriate. (3) Application of the one-minute unit response function to the observed rainfall events showed that the simulated runoff hydrographs were very similar to those observed. This result indicates that the proposed model has a good application potential for the rainfall-runoff analysis in urban basins.