• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.241-252
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• 1998

The objective of the research stated herein is to observe the actual responses of a low-rise nonseismic moment-resisting reinforced concrete frame subjected to varied levels of earthquake ground motions. First, the reduction scale for the model was determined as 1 : 5 considering the capacity of the shaking table to be used and the model was manufactured according to the similitude law. This model was, then, subjected to the shaking table motions simulating Taft N21E component earthquake ground motions, whose peak ground accelations (PGAs) were modified to 0.12g, 0.2g, 0.3g, and 0.4g. The lateral accelerations and displacements at each story and local deformations at the critical reginos of the structure were measured. The base shear was measured by using self-made load cells. Before and after each earthquake simulation test, free vibration tests were performed to find the change in the natural period and damping ratio of the model. The test data on the global and local behaviors are interpreted. The model showed the linear elastic behavior under the Taft N21E motion with the PGA if 0.12g, which represents the design earthquake in Korea. The maximum base shear was 1.8tf, approximately 4.7 times the design base shear. The model revealed fairly good resistance to the higher level of earthquake simulation tests. The main components of its resistance to the high level of earthquakes appeared to be 1) the high overstrength, 2) the elongation of the fundamental period, and 3) the minor energy dissipation by inelastic deformations. The drifts of the model under these tests were approximately within the allowable limit.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.18 no.1_2
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• pp.27-32
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• 2012

There are many possibilities that recycled papers adulterate contaminants during the process. The objective of this research was to evaluate safety of paper-based packaging materials for food, especially commercial pizza boxes in Korea. Ultimately, we compared recycled and non-recycled commercial paper packaging materials. This study was based on Korean Food and Drug Administration (KFDA) regulation. PCBs were measured by GC-ECD. Arsenic and lead were analyzed using an ICP-MS. Formaldehyde was determined by LC-MS. Fluorescent materials were detected by UV lamp. The result of this study shows that non-recycled paper packaging materials meets all the tested hygienic specifications for food packaging materials, whereas recycled paper-based paperboard box may be contaminated by fluorescent whitening agent. Though these results need to be further studied, it is recommended to avoid using recycled paper in direct contact with food when used in food packaging.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.3
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• pp.191-204
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• 2017

Concerns on the air pollution problem caused by ambient fine particles have become a big social issue in Korea. Important factors that should be addressed to develop effective and efficient air quality management policy, especially, against fine particles are discussed and research and policy directions to address these factors are suggested. It is suggested that two factors are in high priority; one is scientific understanding of the major formation mechanisms of fine particles and the other is the process of policy decision and implementation. For the scientific understanding, smog chamber measurement, intensive field study, and chemical transport model development that can simulate the characteristics of Northeast Asia are considered to be important. For the policy directions, priority setting of the proposed policies and development and implement of effective communication sytem are considered to be important.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.1-7
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• 2016

In order to treat electrolysis nickel plating pickling wastewater to meet the effluent limit less than 3.0 mg/L, the electrolysis process by using soluble and insoluble electrode were studied. Electrolysis using soluble electrodes has a characteristic of easy elution from the electrode which the insoluble electrodes close not release metal from the electrode. For these reasons, there exist different characteristics in nickel removal efficiency, purity of nickel sludge. With this connection, the feasibility test were concluded to develop optimal conditions for the treatment of pickling wastewater electrolysis by using soluble electrodes, insoluble electrodes. Optimal condition of current density, pH were derived from the pickling wastewater using insoluble electrodes. It was concluded the highest removal efficiency of nickel at the operation condition of at pH 9, current density of $15mA/cm^2$. At these conditions, 95.3% purity of nickel sludge was achieved, iron content was 2.9%. Optimal condition when using soluble electrodes was derived current density of $10mA/cm^2$, pH 9. Purity of nickel sludge was 77.3%, iron content was 21.0%. 50.7% and 24.2% of operating cost can be saved by the use of soluble electrodes and the use of insoluble electrodes, respectively.

• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.205-210
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• 1998

This study was carried out for the dietary safety based on the level of pesticide residues in 19 kinds of agricultural products consumed in Kangwon-do, Korea. From April 1995 to December 1997, eight organochlorine pesticides in 673 samples were analyzed by using GLC-ECD. According to the results, one kind of pesticides were detected in 159(23.6%) samples and two kinds were in 24(15.1%). While Chlorobenzilate, Dicofol and Tetradifon were not found. Detection ranges of pesticides were $0.001{\sim}0.117ppm$ for DDT, $0.001{\sim}0.095ppm$ for ${\gamma}-BHC$, $0.001{\sim}0.067ppm$ for ${\alpha},{\beta}-Endosulfan$, $0.003{\sim}0.250ppm$ for Chlorothalonil and 0.033ppm for Captafol. Average residues were 0.006ppm for DDT, 0.009ppm for ${\gamma}-BHC$, 0.008ppm for ${\alpha},{\beta}-Endosulfan$, 0.024ppm for Chlorothalonil and 0.033ppm for Captafol, respectively. Consequently, all of the organochlorine pesticide residues in the analyzed samples were within the maximum residue limits.

• Journal of Biomedical Engineering Research
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• v.19 no.6
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• pp.595-602
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• 1998

Among the apex locators, the frequency dependent type is more accurate and convenient to use than others, But the accuracy of the apex locator is still influenced by the presence of various electrolytes used in root canal treatments. In this study, we have developed a frequency dependent electronic apex locator minimizing the influence of the electrolytes on the measurement of root canal lengths. It was also confirmed that two frequencies of 500Hz and 100kHz are optimal for the measuring impedance compare with commercial product used(400Hz and 8kHz)a and there were no differences in accuracy among the three different types of the waveforms; sinusoidal, triangular, and rectangular waves(p>0.05). Impedance ratio of the two different frequencies represents the position of the file in root canal, and the voltage difference of two signals represents the status of the fluid in the root canal. As a result of compensation using the voltage differences, the errors were decreased on the average from +0.54mm to +0.18mm in $H_2O_2$ solution (p<0.01), and from -0.33mm to -0.01mm in NaOCl solution(p<0.01). The accuracies based on ${\pm}$0.5mm, in $H_2O_2$ and NaOCl solutions were improved with the automatic compensation from 71.1% and 91.1% to 82.2% and 100% respectively.

• The Korean Journal of Pesticide Science
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• v.12 no.4
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• pp.323-334
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• 2008

This experiment was carried out to analyze for pesticide residues in 17 different types of the special of geographical indication. We purchased 3 cereal grains, nuts and seeds, 3 fruits, 8 vegetables, mushrooms and other plants (Korean medicines) mainly at the agricultural cooperative's joints markets. Total 209 pesticides including multi-analysed pesticides (204) and single-analysed pesticides (5 ; acephate, methamidophos, monocrotophos, omethoate, vamidothion) were analysed with a GC/MS/MS, an HPLC/UVD (PDA) and a GC/FPD. No. 83 method and single-analysed method (Screening of multi-pesticide residue in the special products of geographical indication) of Korea Food Code was selected for validation in recovery and interferences of matrice. The results were as follows: among the selected 17 the special products, the residual pesticides were detected in 8 types of the special products (40 in 302 samples, detection ratio; 13.2%). All of the samples were not detected over MRLs, but tebuconazole, procymidone and isoprothioran were detected with considerable high frequency. These results could be used as KFDA official methods for the analysis of pesticide residues in foods and reference data will be provided to the related institutions.

• The Korean Journal of Pesticide Science
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• v.12 no.4
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• pp.357-362
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• 2008

In order to survey the residual characteristics of pesticides and assess their safeties in the agricultural products from markets, the agricultural products were purchased from the wholesale and traditional markets in Cheongju and Jeonju and analyzed the pesticide residues in them. No pesticide residues were found in samples from Cheongju, whereas, in case of samples collected from Jeonju, 3 pesticides including chlorothalonil were detected from 5 samples such as eggplant from wholesale market and 3 pesticides including azoxystrobin were found in tomato and grape from traditional market. Pesticide residues were detected from 10.9% of the total samples and detection levels were less than their maximum residue levels. Their estimated daily intakes ranged from 0.00102 to 0.03616% of their acceptable daily intakes, representing residue levels of the pesticides detected were evaluated to be safe.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.3
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• pp.283-290
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• 2016

Even though existing methods for orthophoto production in traditional photogrammetry are effective in large areas, they are inefficient when dealing with change detection of geometric features and image production for short time periods in small areas. In recent years, the UAV (Unmanned Aerial Vehicle), equipped with various sensors, is rapidly developing and has been implemented in various ways throughout the geospatial information field. The data and imagery of specific areas can be quickly acquired by UAVs at low costs and with frequent updates. Furthermore, the redundancy of geospatial information data can be minimized in the UAV-based orthophoto generation. In this paper, the orthophoto and DEM (Digital Elevation Model) are generated using a standard low-end UAV in small sloped areas which have a rather low accuracy compared to flat areas. The RMSE of the check points is σ_H = ±0.12 m on a horizontal plane and σ_V = ±0.09 m on a vertical plane. As a result, the maximum and mean RMSE are in accordance with the working rule agreement for the airborne laser scanning surveying of the NGII (National Geographic Information Institute) on a 1/500 scale digital map. Through this study, we verify the possibilities of the orthophoto generation in small slope areas using general-purpose low specification UAV rather than a high cost surveying UAV.

• Korean Journal of Food Science and Technology
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• v.41 no.5
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• pp.490-497
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• 2009

The present study was performed to validate an analytical method for veterinary drugs, including amoxicillin, ampicillin, oxolinic acid and flumequin, in meat, fish, and their products as established in the 2007 Korea Food Code, and to monitor the respective drugs in 6 kinds of foods, namely beef, pork, flatfish, rockfish, freshwater eel and shrimp. Additionally, an HPLC-ESI-MS/MS method was developed for the qualification of these veterinary drugs. As a result of monitoring, these drugs were detected in 14 (3.6%) out of 393 samples. In particular, amoxicillin was detected in 9 flatfish samples, and oxolinic acid and flumequin were detected in 4 samples and 1 sample of freshwater eel, respectively. The detection levels of amoxicillin ranged from 0.009 to 0.078 mg/kg, in which 1 sample of flatfish contained more than the MRL (0.05 mg/kg). Flumequin detected in 1 sample of freshwater eel, was less than the MRL (0.5 mg/kg). Therefore, the majority of detected levels were less than the MRLs, with the exception of 2 samples showing amounts that were 1-2 times higher than the MRLs. The detected veterinary drugs were identified and confirmed by the HPLC-ESI-MS/MS method created in this study.