• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.136-141
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• 2010

In situ experiments of Nutrient Enrichment Bioassays (NEBs) were conducted in the field along with in the laboratory to determine which nutrient limited phytoplankton growth as a indicator of primary productivity. For the NEBs, the water was sampled using a polyethylene-lined container and dispensed into 6 L water tank in the laboratory. The control (C, no nutrient spike) and six treatments of phosphorus (P), 2-fold phosphorus (2P), 4-fold phosphorus (4P), nitrate nitrogen ($NO_3$-N), 2-fold nitrate nitrogen ($2NO_3$-N), and phosphorus and nitrate nitrogen (P+$NO_3$-N) were set up in the lacustrine zone near the dam site, Daechung Reservoir in September, 2009 and analyzed the diel changes of total nitrogen (TN), total phosphorus (TP), and chlorophyll-$\alpha$ (Chl-$\alpha$) in the cubitainers. The short-term NEBs showed that algal response in the treatments spiked phosphorus (P, 2P, and 4P) were significantly (p < 0.05) greater than the response in the control (C), and nitrogen-spike. Also, the response in 4P-treatment was greater than those in the P- and 2P-treatments. In contrast, there was no significant differences (p > 0.20) between the $NO_3$-N and $2NO_3$-N treatment. The outcomes of the NEBs suggest that phosphorus limited the phytoplankton growth and nitrogen was not limited in this system. Furthermore, in the N + P treatments, the response was minimum, compared to all other treatments and the control, indicating that even if the system is evidently P-limited system, when added the nitrogen, the response showed the inhibition. Also, > 95% of observed long-term TN:TP ratios in the ambient water showed > 17, which is the criteria of P-limitation, supporting the P-limitation in the system. Overall, these results suggest that phytoplankton biomass near the dam is a direct linear function of P-loading near the watershed, if the phosphorus pool is mainly dissolved fraction.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.2
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• pp.24-32
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• 1999

To develope appropriate soil base for planting on the artificial ground, 9 kinds of soil types(varying the components and mixing ratios) and 3 levels of soil depths(10cm, 15cm, 20cm) were chosen. And their plant growing effects were tested and analysed from the test plant Zoysia japonica. The results of the research are as follows. 1. Among the 9 type of soil mixtures, the "sandy loam" soil type gave the worst effects on germination, disease contamination and ground covering. 2. The soil types like VSH(vermiculite20%+sand70%+humus sawdust10%), VSS(vermiculite 40%+sand 50%+humus sawdust 10%) and VS(vermiculite 70%+sand 30%), where vermiculite and sand were added to, show better germination effect promoted from the better condition of aeration and saturation. 3. The plant growing effects(leaf length and ground covering ratio) was evident under the soil types like VSH(vermiculite20%+sand70%+humus sawdust10%) and VSS(vermiculite40%+sand50%+humus sawdust10%), where organic matters were added to. 4. Vermiculite added soil types effect fast leaf decolorization on the tested Zoysia japonica plant, on the contrary to organic matter mixed soil types including SCS(sandy loam 50%+carbonized rice husk30%+sand20%) and SHS(sandy loam 50%+humus sawdust30%+sand20%) with which green leaves subsist longer. S. Soil depth effect to plant growth was found. And a favorable covering rate was accomplished even at the soil depth of 15cm - the limit soil depth for grass survival - from the soil types where organic matters were mixed to. From this result, the soil depth limit for plant survival could be said to be shall owed if appropriate soil type were based.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.71-80
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• 2001

To understand paleoceanographic environmental changes in the Esat Sea during the transitional period between Holocene and last glacial maximum, geochemical high resolution study was conducted by using a piston core(95PC-1) samples collected from the southernmost part of the Ulleung Basin. Geochemical results reveal that major distinctive paleoceanographic variations in transitional period are prominent. Major elemental concentrations show distinctive variations between glacial and Holocene suggesting changes in sediment supply. $TiO_2/Al_2O_3$ ratio of the sediment indicates different sediment composition between Holocene and glacial period. The content of total organic carbon ranging from 0.5% to 4% during transitional period. These vslues showed 2-4 times and two times higher than those of last glacial and Holocene, respectively. The C/N ratios deduced from organic matters exceed10 during transitional period suggesting terrigenous organic matter are supplied from continent, especially during last glacial maximum. Carbonate contents are relatively stable during Holocene and last glacial maximum with gradual decrease during glacial period with high fluctuation during transitional period. The variations of chemical index of weathering (CIW) also show a distinctive variation between glacial and Holocene, which is coincident with those of carbonate and organic carbon. The grain size distribution indicates that the difference content of silt fraction during Holocene and glacial period is closely related with climatic effect during glacial period. Therefore geochemical differences in sediment composition between Holocene and last glacial maximum is thought to be related to paleoceanographic, sea-level change and local paleoclimatic changes.

• Journal of Bio-Environment Control
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• v.27 no.1
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• pp.86-93
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• 2018

This present study was conducted to develop the domestic cultivation kit using water celery(Oenanthe Stolonifera DC.) seed. As the result of germination rates in 3 type inbred lines, the IT 232354 had the highest initial germination rate and final germination rate, and was selected as the inbred line to be used in the cultivation kit. The development of the domestic cultivation kit was carried out using the IT 232354 seeds. It was possible to cultivate up to 3 times harvest using the same root in this cultivation kit, though the growth decreased rapidly in the $4^{th}$ cultivation. As a result of investigating the effects of the type of nutrient solution on growth of water celery, the overall growth was the lowest in the nutrient solution for Oenanthe Stolonifera DC.(N.S.D.). The shoot growth was similar to that of nutrient solution for leaves and stem vegetables (N.S.L.S.) and amino acid fermentation by-product liquid (A.F.B.L.), however in the root growth, the N.S.L.S. was more effective than A.F.B.L. When it was harvested 4 times consecutively after 1 time of planting, the last survival ratio of A.F.B.L. was 100% while their ratios were 96.4% and 49.8% each for N.S.L.S. and N.S.D. For the growth by cultivation kit type, the hole type cultivation kit increased slightly compared to the 3 hole type cultivation kit in the $1^{st}$ and $2^{nd}$ harvest, but there was no difference in the $3^{rd}$ and $4^{th}$ harvest. Total yield of one cultivation kits showed the 3 hole type cultivation kit is much higher than the 2 hole type cultivation kit. According to the results of this experiment, it is possible to harvest three times by planting one times if it was cultivated using N.S.L.S. and A.F.B.L. in the 3 hole type cultivation kit.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.1-7
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• 2018

$^{68}Ga$ was eluted from a $^{68}Ge/^{68}Ga$ radionuclide generator. $^{68}Ga$ decays into $^{68}Zn$, with a half life=67.8min. The decay is 88.9 % by ${\beta}$+ and 11.1 % by EC. The main ${\beta}$+ decay (87.7 %) is to the ground level of $^{68}Zn$ and it is a pure positron emission branch. A small fraction decays ${\beta}$+ (1.2 %) into an excited level of $^{68}Zn$, which promptly decays into the ground level with a ${\gamma}$ (1.077 Mev). This can constitute prompt gamma contamination in the PET data, if the 1.077 Mev ${\gamma}$ has a scatter interaction in the patient, and generates a lower energy ${\gamma}$ in coincidence with the positron annihilation pair. The purpose of this study was to evaluate standardized uptake value(SUV) before and after applying prompt gamma rays correction on $^{68}Ga$-DOTATOC PET/CT image. Fifty patient underwent PET/CT 1 hour after injection of the $^{68}Ga$-DOTATOC. The SUVmax and SUVmean of lesions and normal tissues (Pituitary, Lung, Liver, Spleen, Kidney, Intestine) were evaluated before and after applying prompt gamma correction on $^{68}Ga$-DOTATOC PET/CT image. Additionally, the SUVmax of each lesions and SUVmean of the soft tissues were measured on images. and target to background ratios (TBR) were calculated as quantitative indices. Among 15 patients, 25 of lesions (Pancreas, Liver, Thoracic Spine, Brain) with increased uptake on $^{68}Ga$-DOTATOC PET/CT image. SUVmax and SUVmean were increased in lesion site and normal tissue after prompt gamma rays correction. TBR was $51.51{\pm}49.28$ and $55.50{\pm}53.12$ before and after prompt gamma rays correction, respectively. (p<0.0001)

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.34-38
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• 2011

Purpose: The SUV is a widely used semi-quantitative index in PET for the estimation of radio-tracer accumulation in VOI. In this study, SUVs from three different PET/CT scanners were assessed, and differences between SUVs were evaluated. Materials and Methods: The PET/CT scanners which were assessed in this study were GEMINI, GEMINI TF 64 (Philips) and Biograph True Point True V 40 (Siemens). The NEMA PET phantom (Data Spectrum Corp., USA) was used to evaluate SUVs. The NEMA PET phantom has6.8 kg weight and three hot inserts. Two different activity distributions for the background and inserts were tested. The activity ratio were 3.7:3.7:7.4:11.1 MBq (1:1:2:3) and 1.85:7.4:9.25:11.1MBq (1:4:5:6) for each of background, insert 1, insert 2 and insert 3. Acquisition time was 2 minutes per bed position and NEMA PET phantom could be covered by two bed positions for all PET/CT scanners. The SUVs from each PET/CT scanner were compared with calculated true value. Results: For both activity ratios, all scanners showed similar results. The differences between each scanner were insignificant. Each scanner showed 91.2%, 85.9% and 87.2% of true SUV for GEMINI, GEMINI TF 64, Biograph True Point TrueV, respectively. Conclusion: For all scanners, SUVs were slightly lower than true value. However, the difference between scanners was insignificant. The SUVs from these scanners would be clinically meaningful if their consistent underestimation is kept in mind.

• Korean Journal of Medicinal Crop Science
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• v.9 no.2
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• pp.91-98
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• 2001

Scutellaria baicalensis G. was cultivated in plots of different soil textures which were sand loam(SL), loam(L) and clay loam(CL). Also three fertilizer conditions were used; non application (NA)treatment, rice straw manure(RSM) treatment and N-P-K, chemical fertilization(CF) treatment. The chemical-physical properties, such as organic matter, available phosphate, $K_2O$, CaO, clay contents and porosity ratio in CL plot with RSM application were the most proper in CL plot and RSM application for the culture of S. baicalensis plants. RSM had very high contents of total nitrogen, 2.25% and C/N ratios, 21.4. Thus the growth of shoot and root in loam plot with RSM treatment were greater compared to that of CL plot with NA treatment. Whereas, The highest baicalin, baicalein and wogonin contents in roots were found in CL plot with RSM treatment. There was significantly positive correlation between aerial and underground parts of plant, yield and contents of T-N, $K_2O$ but negatively correlated with the contents of baicalin, baicalein and wogonin in S. baicalensis roots.

• Geophysics and Geophysical Exploration
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• v.16 no.1
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• pp.18-26
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• 2013

Shear-wave velocity ($v_s$) structures beneath two seismic stations, JJU and JJB on the flanks of the volcano Halla on Jeju island, Korea, were estimated by receiver-function inversion and H-${\kappa}$ stacking applied to 150 teleseismic events ($M_W{\geq}5.5$) recorded since 2007. $P_S$ waves converted at the Moho discontinuity does not appear clearly for northwesterly back-azimuths ($207{\sim}409^{\circ}$, average $308^{\circ}$) at station JJU and southeasterly back-azimuths ($119{\sim}207^{\circ}C$, average $163^{\circ}$) at station JJB. This may be due to a gradual velocity increase at Moho or heterogeneity within the crust. The $v_s$ models derived by inversion of receiver functions indicate a distinct low velocity layer ($v_s{\leq}3.5km/s$; LVL) within the crust and a gradual increase in $v_s$ in the depth interval of 30 to 40 km. Within the radius of 18 km beneath station JJB, the LVL occurs at depths of 14 ~ 26 km and the 'Moho' ($v_s{\geq}4.3km/s$) is at 34 km depth. Ten kilometers to the west, within the radius of 16 km beneath station JJU, both the LVL and the Moho are significantly shallower, at depths of 14 to 24 km and 30 km, respectively. H-${\kappa}$ analyses for stations JJU and JJB yield estimated crustal thickness of 29 and 33 km and $v_p/v_s$ ratios of 1.64 and 1.75, respectively. The lesser $v_p/v_s$ ratio was derived for rocks nearest to th peak of the volcano.

• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.65-71
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• 2019

With regard to current Neck CT, Bismuth shielding boards are often being used to reduce exposure to superficial organs such as the thyroid. However, beam hardening often occurs near superficial organs with Bismuth shielding boards and variations in CT Number, Noise, and Uniformity values occur severely. This study looked into the usefulness of shielding boards made from aluminum and silicone that can be easily obtained and have good machinability by comparing them to the existing Bismuth shielding board. An Aluminum 7.3mm and a Silicone 21.5mm were made with shielding ratios similar to that of the Bismuth(0.06 mmPb). TLD (TLD-100) was placed on the thyroid area of the Phantom (RS-108T) and 5 doses were measured for each. To compare image quality, CT Number and Noise variations in axial images of the thyroid area in Neck CT images were compared. Also, variations in CT Number, Noise, and Uniformity were measured in the AAPM phantom images and compared. In the results, when thyroid doses for each shielding board were compared, the Bismuth shielding board showed a 14% reduction, the Silicone 21.5mm showed a 15% reduction, and the Aluminum 7.3mm showed a 13% reduction compared to the Non-Shield. Statistically, there were no significant differences in comparison with the Bismuth shielding board. In CT Number variations of thyroid area images, variations were largest for the Bismuth shielding board. With Uniformity evaluations of the AAPM phantom, the Bismuth shielding board was found unsuitable and the Aluminum 7.3mm and Silicone 21.5mm satisfied the acceptance criteria. Research results show that the Aluminum 7.3mm and Silicone 21.5mm have a similar shielding ratio to the high-priced Bismuth shielding board that is currently being used clinically and in comparison tests of CT Number attenuation coefficient variations, Noise, and Uniformity which are phantom image evaluation items, they proved to be better than Bismuth shielding boards. If various shielding boards are made using aluminum and silicone, sized appropriately for superficial organs, it would be useful in decreasing patient doses.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.281-302
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• 2023

Carbon is not only an essential element for life but also a key player in climate change. The radiocarbon (¹⁴C) analysis using accelerator mass spectrometry (AMS) is a powerful tool not only to understand the carbon cycle but also to track pollutants derived from fossil carbon, which have a distinct radiocarbon isotope ratio (Δ¹⁴C). Many studies have reported Δ¹⁴C of carbon compounds in streams, rivers, rain, snow, throughfall, fine particulate matter (PM_2.5), and wastewater treatment plant effluents in South Korea, which are reviewed in this manuscript. In summary, (1) stream and river carbon in South Korea are largely derived from the chemical weathering of soils and rocks, and organic compounds in plants and soils, strongly influenced by precipitation, wastewater treatment effluents, agricultural land use, soil water, and groundwater. (2) Unprecedentedly high Δ¹⁴C of precipitation during winter has been reported, which can directly and indirectly influence stream and river carbon. Although we cannot exclude the possibility of local contamination sources of high Δ¹⁴C, the results suggest that stream dissolved organic carbon could be older than previously thought, warranting future studies. (3) The ¹⁴C analysis has also been applied to quantify the sources of forest throughfall and PM_2.5, providing new insights. The ¹⁴C data on a variety of ecosystems will be valuable not only to track the pollutants derived from fossil carbon but also to improve our understanding of climate change and provide solutions.