• Journal of Animal Environmental Science
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• v.13 no.2
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• pp.113-120
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• 2007

This study was conducted to measure Nitrogen(N), Phosphate($P_2O_5$), Potassium ($K_2O$), Organic matter(OM) and Moisture content of liquid pig manure by Near Infrared Spectroscopy(NIRS) and to develop an alternative and analytical instrument which are used for measurement of N, $P_2O_5$, $K_2O$, OM, and Moisture contents for liquid pig manure. The liquid pig manure sample's transmittance spectra were measured with a NIRS in the wavelength range of 400 to 2,500 nm. Multiple linear regression and partial least square regression were used for calibrations. The correlation coefficient(RSQ) and standard error of calibration(SEC) obtained for nitrogen were 0.9190 and 2.1649, respectively. The RSQ for phosphate, potassium, organic matter and moisture contents were 0.9749, 0.5046, 0.9883 and 0.9777, and the SEC were 0.5019, 1.9252, 0.1180 and 0.0789, respectively. These results are indications of the rapid determination of components of liquid pig manure through the NIR analysis. The simple analytical instrument for liquid pig manure consisted of a tungsten halogen lamp for light source, a sample holder, a quartz cell, a SM 301 spectrometer for spectrum analyzer, a power supply, an electronics, a computer and a software. Results showed that the simple analytical instrument that was developed can approximately predict the phosphate, organic matter and moisture content of the liquid pig manure when compared to the analysis taken by NIRS. The low predictability value of potassium however, needs further investigation. Generally, the experiment proved that the simple analytical instrument was reliable, feasible and practical for analyzing liquid pig manure.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.408-419
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• 2007

In the child, it is very important that he/she will have the ability to suppress aesthetic restorative materials of secondary caries. With the representative preventive material against caries, the importance of fluoride is more emphasized. This study examined the differences in fluoride release and re-uptake among some restorative materials, following a treatment of APF gel and fluoride varnish. The surface roughness was observed under scanning electron microscope. Studying this will provide for the research to find effective restorative materials and fluoride type in tooth caries prevention. It is applied from presence at a clinic that restorative materials are resin, flowable resin, compomer and glass ionomer. Fluoride release was measured at 24-hour intervals for 7 days, 3-day intervals from 8th to 38th day using an ion-selective electrode and analyzer. Then, the materials were treated with the fluoride gel and fluoride varnish respectively, fluoride release was measured and specimens were evaluated under scanning electron microscope for 4 weeks. It was concluded that 1. Fluoride was released for 38 days from restorative materials under 1 ppm in case of flowable resin, 1-2 ppm in compomer and 2-8 ppm in glass ionomer, a few of fluoride was released after 45 days 2. Fluoride has more releasing after application of APF gel than fluoride varnish. Fluoride re-uptake was observed under 0.6-0.2 ppm in fluoride varnish and 0.6-2.6 ppm in APF gel after starting the procedure one day(p<0.05). For the remaining 4 weeks, they demonstrated a similar release. 3. Specimens were evaluated under scanning electron microscope. Applied fluoride in the experimental group surface was rougher than the control group that did not receive fluoride application. Fluoride varnish group had a smoother surface than both the APF gel group and the varnish APF gel group that received a fluoride application.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.1
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• pp.40-47
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• 2006

Purpose: The aim of this study was to examine the effects of attenuation correction (AC) and scatter correction (SC) on the quantification of PET count rates. Materials and Methods: To assess the effects of AC and SC $^{18}F$-FDG PET images of phantom and cat brain were acquired using microPET R4 scanner. Thirty-minute transmission images using $^{68}Ge$ source and emission images after injection of FDG were acquired. PET images were reconstructed using 2D OSEM. AC and SC were applied. Regional count rates were measured using ROIs drawn on cerebral cortex including frontal, parietal, and latral temporal lobes and deep gray matter including head of caudate nucleus, putamen and thalamus for pre- and post-AC and SC images. The count rates were then normalized with the injected dose per body weight. To assess the effects of AC, count ratio of "deep gray matter/cerebral cortex" was calculated. To assess the effects of SC, ROIs were also drawn on the gray matter (GM) and white matter (WM), and contrast between them ((GM-WM)/GM was measured. Results: After the AC, count ratio of "deep gray matter/cerebral cortex" was increased by $17{\pm}7%$. After the SC, contrast was also increased by $12{\pm}3%$. Conclusion: Relative count of deep gray matter and contrast between gray and white matters were increased after AC and SC, suggesting that the AC would be critical for the quantitative analysis of cat brain PET data.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.123-131
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• 2009

Purpose: We tested a sample of nuclear medicine workers at Korean healthcare institutions for internal contamination with radioactive isotopes, measuring concentrations and evaluating doses of individual exposure. Materials and Methods: The detection and measurement was performed on urine samples collected from 25 nuclear medicine workers at three large hospitals located in Seoul. Urine samples were collected once a week, 100~200 mL samples were gathered up to 6~10 times weekly. A high-purity germanium detector was used to measure gamma radiations in urine samples for the presence of radioactive isotopes. Based on the detection results, we estimated the amounts of intake and committed effective doses using IMBA software. In cases where committed effective doses could not be adequately evaluated with IMBA software, we estimated individual committed effective doses for radionuclides with a very short half life such as $^{99m}Tc$ and $^{123}I$, using the methods recommended by International Atomic Energy Agency. Results: Radionuclides detected through the analysis of urine samples included $^{99m}Tc$, $^{123}I$, $^{131}I$ and $^{201}Tl$, as well as $^{18}F$, a nuclide used in Positron Emission Tomography examinations. The committed effective doses, calculated based on the radionuclide concentrations in urine samples, ranged from 0 to 5 mSv, but were, in the majority of cases, less than 1 mSv. The committed effective dose exceeded 1 mSv in three of the samples, and all three were workers directly handling radioactive sources. No nurses were found to have a committed effective dose in excess of 1 mSv. Conclusions: To improve the accuracy of results, it may be necessary to conduct a long-term study, performed over a time span wide enough to allow the clear determination of the influence of seasonal factors. A larger sample should also help increase the reliability of results. However, as most Korean nuclear medicine workers are currently not necessary to monitored routinely for internal contamination with radionuclides. Notwithstanding, a continuous effort is recommended to reduce any unnecessary exposure to radioactive substances, even if in inconsequential amounts, by regularly surveying workplace environments and frequently monitoring atmospheric concentrations of radionuclides.

• Journal of Astronomy and Space Sciences
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• v.24 no.2
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• pp.125-134
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• 2007

In this paper, we analyze the orbital variation of the Korea Multi-Purpose SATellite-1(KOMPSAT-1) in a strong space environment due to satellite drag by solar and geomagnetic activities. The satellite drag usually occurs slowly, but becomes serious satellite drag when the space environment suddenly changes via strong solar activity like a big flare eruption or coronal mass ejections(CMEs). Especially, KOMPSAT-1 as a low earth orbit satellite has a distinct increase of the drag acceleration by the variations of atmospheric friction. We consider factors of solar activity to have serious effects on the satellite drag from two points of view. One is an effect of high energy radiation when the flare occurs in the Sun. This radiation heats and expands the upper atmosphere of the Earth as the number of neutral particles is suddenly increased. The other is an effect of Joule and precipitating particle heating caused by current of plasma and precipitation of particles during geomagnetic storms by CMEs. It also affects the density of neutral particles by heating the upper atmo-sphere. We investigate the satellite drag acceleration associated with the two factors for five events selected based on solar and geomagnetic data from 2001 to 2002. The major results can be summarized as follows. First, the drag acceleration started to increase with solar EUV radiation with the best cross-correlation (r = 0.92) for 1 day delayed F10.7. Second, the drag acceleration and Dst index have similar patterns when the geomagnetic storm is dominant and the drag acceleration abruptly increases during the strong geomagnetic storm. Third, the background variation of the drag accelerations is governed by the solar radiation, while their short term (less than a day) variations is governed by geomagnetic storms.

• Korean Journal of Organic Agriculture
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• v.24 no.1
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• pp.73-85
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• 2016

This study was carried out to allelopathic effects of aqueous extracts on Coronopus didymus in order to investigate the competitive dominant in plant ecosystem and possibility application in natural herbicide. Number of species and species diversity for close to patch of C. didymus was decreased gradually site #1 (7, 1.76), site #2 (5, 1.34) and site #3 (5, 1.25). It was generally decreased the relative germination ratio (r=-0.731, p<0.01), the mean germination time, the relative elongation ratio (r=-571, p<0.01, r=-0.730, p<0.01), the relative fresh weight (r=-0.743, p<0.01), development of root hairs of receptor plants by concentration of the aqueous extracts from C. didymu. But they were different from the growing regions, the kind of receptor plants and the treatment of the aqueous extracts. Especially, it was differently effected among growing regions that inhibited more radicle than shoot by the aqueous extracts concentration of C. didymus. Total phenolic compound in the aqueous extracts of C. didymus analyzed about $23.0{\pm}1.1mg/g$. Total phenolic compounds of soil in survey area was increased gradually site #1 ($0.072{\pm}0.002mg/g$), site #2 ($0.082{\pm}0.003mg/g$) and site #3 ($0.092{\pm}0.004 mg/g$). We think that the aqueous extracts of C. didymu showed allelopathic effects on other plants. Therefore, C. didymu hold the competitive dominant of plant ecosystem in Jeju Island and possibility application of natural herbicide.

• Environmental Analysis Health and Toxicology
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• v.15 no.4
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• pp.131-137
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• 2000

The release of hazardous waste materials into the environment poses serious risks in humans and ecosystems. The risk assessment of environmental pollutants including hazardous chemicals requires a comprehensive measurement of hazard and exposure of the chemicals that can be achieved by toxicity evaluation using a biological system such as biomarkers. In this report we have tried to develop a biomarker used to elucidate a molecular basis of, and to monitor abnormal behaviors caused by diazinon in Japanese medaka (Oryzias latipes) as a model organism. First, an attempt was made to clone tyrosine hydroxylase gene from Japanese medaka that would be a candidate for a biomarker for neuronal modulations and behaviors. For monitoring experiments at behavioral and molecular biological levels, the fish were treated under different sublethal conditions of diazinon and their behavioral responses were observed . In this study we have successfully cloned a partial TH gene from the medaka fish through PCR screening of an ovary cDNA library. DNA sequencing analysis revealed that the amplified fragment was 327 bp encoding 109 amino acids. Comparing the DNA sequence of medaka TH with other species, TH gene revealed the DNA sequence was completely identical to that of rat TH. In the RT-PCR, 330 Up of mRNA was consistently amplified in all the treated samples including control There were no significant differences in the TH expression level regardless of treating concentrations (1∼5,000 ppb) and time (0∼48 hr) The reason appeared to be that RT-PCR was not performed using through a quantitative analysis normalized against an actin gene expression. Organ or tissue - specific detection of TH activity and mRNA as biomarkers will be a useful monitoring tool for neurobehavioral changes in fish influenced by toxic chemicals. Furthermore, quantitative analysis of locomotive patterns and its correlation with the neurochemical and molecular data would be highly useful in measuring toxicity and hazard ofvarious environmental pollutants.

• Korean Journal of Environmental Agriculture
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• v.12 no.2
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• pp.112-120
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• 1993

The use of fertilizer N is essential for maximum economic yield of crops. Meanwhile, enrichment of $NO_3^-$in the environment has to be avoided. Winter barley crop has a short duration of growth before winter, but is used to receive N greater than 60 kg/ha at seeding. Experiments were performed to determine the quantitative aspect of the fate of soil applied urea N among the residual, leached, and uptaken by winter barley (cv. Olbori), and to evaluate the effect of soil temperature on nitrification. Four levels of urea (0, 40, 80, and 120 kg N/ha) was basal-dressed to Olbori. $NH_4^+$ appeared dominant in the soil until 40 days after seeding, whereas $NO_3^-$ did thereafter. Nitrification rate at $5^{\circ}C$ of soil temperature was 40 to 50% of that at $15^{\circ}C. Linear increases in the number of ammonia oxidizing and nitrite oxidizing bacteria of the soil was present as the level of urea fertilization was higher. Less than 60% of N applied at seeding was uptaken by winter barley until mid-March but 50% was lost from death of older barley leaves during overwintering. Thereby only 10% of the applied N remained in the barley in spring. Only 15% of the applied N was present in the rhizosphere. The 17 to 20% of the soil applied N leached out as $NO_3^-$ the rhizosphere. Nitrogen leaching during winter was estimated to be 16 and 20 kg/ha when the basal application level of urea fertilization was 80 and 120 kg/ha, respectively.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.57-65
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• 2005

In a forest ecosystem, the major source of soil carbon input is from litterfall and its decomposition. To understand the effect of litterfall and litter decomposition on seasonal variation of soil respiration and litter decomposition rates were measured in temperate deciduous forest in Korea. Annual litterfall collected from litter trap (1m x 1m) were 147.5 ± 8.2g Cm/sup -2/ yr/sup -1/ in 2003. About 47% of litterfall were Quercus serrata leaf followed by Carpinus laxiflora leaf (27 %), Carpinus cordata leaf (7 %), and others, such as other leaf, bark, branch, and acorn, were 20%. The decomposition rate was the highest in C. cordata (33.03%, k = 0.46), followed by C. laxiflora (25.73%, k = 0.30), and Q. serrata (24.17%, k = 0.28). The continuous measurement of soil respiration from January 2004 to December 2004 was carried out using AOCC (Automatic Open-Closed multi-Chamber system). The annual soil respiration rate was 629.6g Cm/sup -2/ yr/sup -1/ and the litter decomposition was 30.0g Cm/sup -2/ yr/sup -1/. The portion of litter decomposition rate on soil respiration rate was about 5%. From January to February, when the soil respiration rate was the lowest, about 11 % of soil respiration (7.4 ± l.4g Cm/sup -2/ month/sup -1/) were effected by litter decomposition rate (0.8g Cm/sup -2/ month/sup -1/). The highest soil respiration rate (111.5 ± 16.2g Cm/sup -2/ month/sup -1/) and litter decomposition rate (11.4g Cm/sup -2/ month/sup -1/) were showed in July to August. According to the regression analysis between soil respiration rate and litter decomposition, the soil respiration rate were related to litter decomposition with the correlations (r = 0.63).

• Journal of Aquaculture
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• v.11 no.3
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• pp.371-380
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• 1998

This study has been conducted to develop the techniques for spat production of the sun and moon scallop from January 1995 to December 1996. With the adult scallops collected from the Sogwipo area, spawning induction and larvae rearing were attempted several times and monthly changes of GSI were also monitored during the experimental period. The results obtained wre as follows. 1. GSI started to increase from June and showed the maximum value of 22.17 and 14.98 in female and male respectively in November, and then gradually decreased from December. 2. Spawning induction by heating method turned out to the most efficient way showing the responding rate of 64.8~91.5%. The responding temperature was $21.4~26.4{\circ}C$ which was $3.1~8.5{\circ}C$ increased from the rearing temperature of $16.3~18.3{\circ}C$. An average number of eggs spawned was $9.2{\times}10^5$ 3. the average size of eggs after fertilization was about $72{\mu}m$ in diameter. The first polar body discharge, blastula formation, and trochopore larvae appearance occurred 30 mininutes, 18 hours, and 22 hours after fertilization respectively. 4. Settling rates in various collectors were similar one another, whereas pouring larvae in the mesh was the most efficient way for larval setting. 5. The spates grew to be 1mm in their shell length for the first 50 days after fertilization and 9.6mm in 135days. 6. Correlation between shell length (SL) of the spat and the number of days (X) after spat settlement could be expressed as $SL=257.75e ^{0.0272x}$(r=0.9100).