• Journal of Korean Society for Atmospheric Environment
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• v.34 no.3
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• pp.430-446
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• 2018

To improve understanding of the sources and chemical properties of particulate pollutants on the Korean Peninsula, An Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) measured non-refractory fine particle ($NR-PM_1$) from 2013 to 2015 at Baengnyeong Island and Seoul metropolitan area (SMA), Korea. The chemical composition of $NR-PM_1$ in Baengnyeong island was dominated by organics and sulfate in the range of 36~38% for 3 years, and the organics were the dominant species in the range of 44~55% of $NR-PM_1$ in Seoul metropolitan area. The sulfate was found to be more than 85% of the anthropogenic origin in the both areas of Baengnyeong and SMA. Ratio of gas to particle partition of sulfate and nitrate were observed in both areas as more than 0.6 and 0.8, respectively, representing potential for formation of additional particulate sulfate and nitrate. The high-resolution spectra of organic aerosol (OA) were separated by three factors which were Primary OA(POA), Semi-Volatility Oxygenated Organic Aerosol (SV-OOA), and Low-Volatility OOA(LV-OOA) using positive matrix factorization (PMF) analysis. The fraction of oxygenated OA (SOA, ${\fallingdotseq}OOA$=SV-OOA+LV-OOA) was bigger than the fraction of POA in $NR-PM_1$. The POA fraction of OA in Seoul is higher than it of Baengnyeong Island, because Seoul has a relatively large number of primary pollutants, such as gasoline or diesel vehicle, factories, energy facilities. Potential source contribution function (PSCF) analysis revealed that transport from eastern China, an industrial area with high emissions, was associated with high particulate sulfate and organic concentrations at the Baengnyeong and SMA sites. PSCF also presents that the ship emissions on the Yellow Sea was associated with high particulate sulfate concentrations at the measurement sites.

• The Korean Journal of Physiology
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• v.21 no.2
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• pp.211-223
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• 1987

Head-down tilt (HDT) at $-6^{\circ}$ has been commonly used as the experimental model in both man and animals to induce the blood shift toward the head or central protion of the body, demonstrating similar physiological effect encountered in the weightlessness in the orbital flight. There are few reports about the physiological response upon the cardiovascular regulatory system or the tolerance to the $(-6^{\circ})$ HDT within a relatively short period less than 1 hour. Therefore, the purpose of this study way to observe the effects of $-6^{\circ}$ HDT on cardiovascular system within 30 minutes and to evaluate early regulatory mechanism for simulated hypogravity. Ten mongrel dogs weighing 8-12 kg were anesthetized with the infusion of 1% ${\alpha}-chloralose$ (100 mg/kg) intravenously, and the postural changes were performed from the supine to the $-6^{\circ}$ head-down Position, then from the head-down to the supine (SUP), and each posture was maintained for 30 minutes. Blood flow $({\dot{Q}})$ through common carotid and femoral arteries were determined by the electromagnetic flowmeter. Mean arterial pressure (MAP), heart rate (HR), respiratory rate , and pH, $P_{O_2}$, $P_{CO_2}$ and hematocrit (Hct) of arterial and venous blood were also measured. The peripheral vascular resistance was calculated by dividing respective MAP values by ${\dot{Q}}$ through both sides of common carotid or femoral arteries. The concentration of plasma epinephrine and norepinephrine was determined by Peuler & Johnson's radioenzymatic method. The results are summarized as follows: In the initial 5 minutes in $-6^{\circ}$ HDT, HR was significantly (p<0.05) increased and MAP slightly decreased. Although ${\dot{Q}}$ and carotid peripheral artery resistance were not significantly changed, ${\dot{Q}}$ through femoral artery was diminished and femoral peripheral artery resistance was elevated. In the SUP, the initial changes of MAP and HR were increased (p<0.05), but those of ${\dot{Q}}$ and peripheral vascular resistance through both common carotid and femoral arteries were not significant. After 10 minutes of each postural change in both HDT and SUP, MAP was maintained almost equal to that of the level of pretilting control. During 60 minutes of both postural changes of HDT and SUP, $P_{O_2}$ and Hct were not changed significantly. However pH tended to increase slowly and $P_{CO_2}$ was gradually decreased. The pH and $P_{CO_2}$ seemed to be related to the increased respiratory rate. Plasma epinephrine concentration was not changed significantly and plasma norepinephrine concentration was slightly decreased in the course of HDT and also at 10 minutes of SUP. However these concentration changes were statistically insignificant. From these results, it may be concluded that the effect of $-6^{\circ}$ HDT for 30 minutes on the cardiovascular system and plasma catecholamine levels of the dog is minimum and it is suggestive that the cardiovascular regulatory mechanism, possibly mediated by so called gravity receptors including baroreceptor and volume receptor, has been properly and adequately operated.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.123-158
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• 2009

An attempt was made to stimulate future research by providing exemplary information, which would integrate published knowledge to solve specific pest problem caused by resistance. This review was directed to find a way for delaying resistance development with consideration of chemical(s) nature, of mixture, rotation, or mosaics, and of insecticide(s) compatible with the biological agents in integrated pest management (IPM). The application frequency, related to the resistance development, was influenced by insecticide activity from potentiation, residual period, and the vulnerability to resistance development of chemical, with secondary pest. Chemical affected feeding, locomotion, flight, mating, and predator avoidance. Insecticides with negative cross-resistance by the difference of target sites and mode of action would be adapted to mixture, rotation and mosaic. Mixtures for delaying resistance depend on each component killing very high percentage of the insects, considering allele dominance, cross-resistance, and immigration and fitness disadvantage. Potential disadvantages associated with mixtures include disruption of biological control, resistance in secondary pests, selecting very resistant population, and extending cross-resistance range. The rotation would use insecticides in high and low doses, or with different metabolic mechanisms. Mosaic apply insecticides to the different sectors of a grid for highly mobile insects, spray unrelated insecticides to sedentary aphids in different areas, or mix plots of insecticide-treated and untreated rows. On the evolution of pest resistance, selectivity and resistance of parasitoids and predator decreased the number of generations in which pesticide treatment is required and they could be complementary to refuges from pesticides To enhance the viability of parasitoids, the terms on the insecticides selectivity and factors affecting to the selectivity in field were examined. For establishment of resistant parasitoid, migration, survivorship, refuge, alternative pesticides were considered. To use parasitoids under the pressure of pesticides, resistant or tolerant parasitoids were tested, collected, and/or selected. A parasitoid parasitized more successfully in the susceptible host than the resistant. Factors affecting to selective toxicity of predator are mixing mineral oil, application method, insecticide contaminated prey, trait of individual insecticide, sub-lethal doses, and the developmental stage of predators. To improve the predator/prey ratio in field, application time, method, and formulation of pesticide, reducing dose rate, using mulches and weeds, multicropping and managing of surroundings are suggested. Plant resistance, predator activity, selective insect growth regulator, and alternative prey positively contributed to the increase of the ratio. Using selective insecticides or insecticide resistant predator controlled its phytophagous prey mites, kept them below an economic level, increased yield, and reduced the spray number and fruits damaged.

• The Korean Journal of Air & Space Law and Policy
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• v.30 no.2
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• pp.337-371
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• 2015

In recent years, aviation safety has been facing new hazards due to the rapidly changing environment in which aircraft operation increasingly finds. Continuously increasing air traffic volume, integration of various cultures from many States, and many other changes are the causal factors of the new risks. To identify such new hazards and risks, the government of the Republic of Korea (ROK) established aviation safety reporting systems in accordance with the international standards of the Convention on International Civil Aviation. However, there are some misunderstandings by the government in operating and by the personnel who take part in these reporting systems. Everybody should understand that aviation safety reporting system is not a punitive measure but a tool for collecting data in order to improve safety. In addition, such a system can be utilized further to promote an improved awareness on the need for a proper safety culture on the part of both the government, the industry and the personnel. This paper includes studies on international standards, relevant regulations in the United States and the United Kingdom. Moreover, this paper proposes to the government of ROK several points to improve their own system, including integration of the existing reporting systems, improvement of reporting items, implementation of safety data taxonomy and the establishment of safety data protection.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.180-188
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• 2014

It is very important accurate diagnosis and quick treatment in cerebrovascular disease, i.e. stenosis or occlusion that could be caused by risk factors such as poor dietary habits, insufficient exercise, and obesity. Time-of-flight magnetic resonance angiography (TOF-MRA), it is well known as diagnostic method without using contrast agent for cerebrovascular disease, is the most representative and reliable technique. Nevertheless, it still has measurement errors (also known as overestimation) for length of stenosis and area of occlusion in celebral infarction that is built by accumulation and rupture of plaques generated by hemodynamic turbulence. The purpose of this study is to show clinical trial feasibility for 3D-SPACE T2, which is improved by using signal attenuation effects of fluid velocity, in diagnosis of cerebrovascular disease. To model angiostenosis, strictures of different proportions (40%, 50%, 60%, and 70%) and virtual blood stream (normal saline) of different velocities (0.19 ml/sec, 1.5 ml/sec, 2.1 ml/sec, and 2.6 ml/sec) by using dialysis were made. Cross-examinations were performed for 3D-SPACE T2 and TOF-MRA (16 times each). The accuracy of measurement for length of stenosis was compared in all experimental conditions. 3D-SPACE 2T has superiority in terms of accuracy for measurements of the length of stenosis, compared with TOF-MRA. Also, it is robust in fast blood stream and large stenosis than TOF-MRA. 3D-SPACE 2T will be promising technique to increase diagnosis accuracy in narrow complex lesions as like two cerebral small vessels with stenosis, created by hemodynamic turbulence.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.947-958
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• 2021

This study was conducted to provide basic data for crop monitoring by comparing and analyzing changes in reflectance and vegetation index by sensor of multi-spectral sensors mounted on unmanned aerial vehicles. For four types of unmanned aerial vehicle-mounted multispectral sensors, such as RedEdge-MX, S110 NIR, Sequioa, and P4M, on September 14 and September 15, 2020, aerial images were taken, once in the morning and in the afternoon, a total of 4 times, and reflectance and vegetation index were calculated and compared. In the case of reflectance, the time-series coefficient of variation of all sensors showed an average value of about 10% or more, indicating that there is a limit to its use. The coefficient of variation of the vegetation index by sensor for the crop test group showed an average value of 1.2 to 3.6% in the crop experimental sites with high vitality due to thick vegetation, showing variability within 5%. However, this was a higher value than the coefficient of variation on a clear day, and it is estimated that the weather conditions such as clouds were different in the morning and afternoon during the experiment period. It is thought that it is necessary to establish and implement a UAV flight plan. As a result of comparing the NDVI between the multi-spectral sensors of the unmanned aerial vehicle, in this experiment, it is thought that the RedEdeg-MX sensor can be used together without special correction of the NDVI value even if several sensors of the same type are used in a stable light environment. RedEdge-MX, P4M, and Sequioa sensors showed a linear relationship with each other, but supplementary experiments are needed to evaluate joint utilization through off-set correction between vegetation indices.

• Korean Journal of Remote Sensing
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• v.30 no.1
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• pp.61-73
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• 2014

This study reviewed an application of water quality estimation using an Airborne Hyperspectral Imagery (A-HSI) and tested a part of Han River water quality (especially suspended solid) estimation with available in-situ data. The estimation of water quality was processed two methods. One is using observation data as downwelling radiance to water surface and as scattering and reflectance into water body. Other is linear regression analysis with water quality in-situ measurement and upwelling data as at-sensor radiance (or reflectance). Both methods drive meaningful results of RS estimation. However it has more effects on the auxiliary dataset as water quality in-situ measurement and water body scattering measurement. The test processed a part of Han River located Paldang-dam downstream. We applied linear regression analysis with AISA eagle hyperspectral sensor data and water quality measurement in-situ data. The result of linear regression for a meaningful band combination shows $-24.847+0.013L_{560}$ as 560 nm in radiance (L) with 0.985 R-square. To comparison with Multispectral Imagery (MSI) case, we make simulated Landsat TM by spectral resampling. The regression using MSI shows -55.932 + 33.881 (TM1/TM3) as radiance with 0.968 R-square. Suspended Solid (SS) concentration was about 3.75 mg/l at in-situ data and estimated SS concentration by A-HIS was about 3.65 mg/l, and about 5.85mg/l with MSI with same location. It shows overestimation trends case of estimating using MSI. In order to upgrade value for practical use and to estimate more precisely, it needs that minimizing sun glint effect into whole image, constructing elaborate flight plan considering solar altitude angle, and making good pre-processing and calibration system. We found some limitations and restrictions such as precise atmospheric correction, sample count of water quality measurement, retrieve spectral bands into A-HSI, adequate linear regression model selection, and quantitative calibration/validation method through the literature review and test adopted general methods.

• Journal of the Korean Magnetics Society
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• v.26 no.3
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• pp.92-98
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• 2016

To aim of this study was to assess the full scan and half scan of imaging with half scan factor. Patients without a cerebral vascular disease (n = 30) and were subject to the full scan half scan, and set a region of interest in the cerebral artery from the three regions (C1, C2, C3) in the range of 7 to 8 mm. MIP (maximum intensity projection) to reconstruct the images in signal strength SNR (signal to noise ration), PSNR (peak signal noise to ratio), RMSE (root mean square error), MAE (mean absolute error) and calculated by paired t-test for use by statistics were analyzed. Scan time was half scan (4 minutes 53 seconds), the full scan (6 minutes 04 seconds). The mean measurement range (7.21 mm) of all the ROI in the brain blood vessel, was the SNR of the first C1 is completely scanned (58.66 dB), half-scan (62.10 dB), a positive correlation ($r^2=0.503$), for the second C2 SNR is completely scanned (70.30 dB), half-scan (74.67 dB) the amount of correlation ($r^2=0.575$), third C3 of a complete scan SNR (70.33 dB), half scan SNR (74.64 dB) in the amount of correlation between the It was analyzed with ($r^2=0.523$). Comparative full scan with half of SNR ($4.75{\pm}0.26dB$), PSNR ($21.87{\pm}0.28dB$), RMSE ($48.88{\pm}1.61$), was calculated as MAE ($25.56{\pm}2.2$). SNR is also applied to examine the half-scans are not many differences in the quality of the two scan methods were not statistically significant in the scan (p-value > .05) image takes less time than a full scan was used.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.2
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• pp.94-101
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• 1989

Transport properties of 2DEG at AlGaAs/GaAs interface such as average electron energy, flight distance, each valley occupancy ratio, average electron velocity for various fields are investigated by MONTE-CARLO method. As the electric field increases, more electrons transit drastically from (000) valley to (000) upper valley. This phenomenon shows the nonstationary effect such as velocity overshoot. The duration of the transient decreases from about 1.4 psec for electric field E = 7KV/cm to about 0.7 psec for 12KV/cm. The average electron velocity during transient transport in 2DEG is about 8 times the steady-state velocity for E = 12KV/cm at room temperature. In comparison with bulk GaAs the peak velocity in the 2DEG is higher than that in even pure bulk GaAs at electric field E = 7 KV/cm. On the basis of the fact that the electrons in the 2DEG have larger peak velocity and shorter transient time of velocity than those in the bulk GaAs, it is suggested that the device with 2DEG may obtain higher mobility than that with bulk GaAs.

• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.284-289
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• 2017

Oxidized polyethylene wax (OPEW) is, one of the food additives, used as a coating agent in citrus fruits and nuts. OPEW is authorized to quantum satis in EU, USA, and is acceptable less than 250 mg/kg in Australia and New Zealand. But OPEW is unauthorized as a food additive in Korea. This study was to establish the analytical method of OPEW and demonstrate the effective application of various food samples. We first conducted to compare the various analytical method including acid value (AV), high temperature gel permeation chromatography (HT-GPC), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS), gas chromatography flame ionization detector (GC-FID) and fourier transform infrared spectroscopy (FT-IR). This result indicated that FT-IR spectrum of OPEW treated food sample displayed absorption bands for carbonyl group (C=O, $1714cm^{-1}$), ester group (C-O, $1463cm^{-1}$), aliphatic group (C-H, $2916cm^{-1}$). Furthermore, IR spectrum of OPEW treated food sample showed similar tendency with IR spectrum of OPEW standard. Therefore, it is confirmed that analytical method using FT-IR can be detected on analysis of OPEW in food. As a result of monitoring of 111 samples using established analytical method, OPEW was not detected in the food samples.