• The Korean Journal of Nuclear Medicine Technology
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• v.27 no.2
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• pp.111-127
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• 2023

Purpose: Gallium-68 (⁶⁸Ga) is increasingly used in nuclear medicine imaging for various conditions such as lymphoma and neuroendocrine tumors by labeling tracers like Prostate Specific Membrane Antigen (PSMA) and DOTA-TOC. However, compared to Fluorine-18 (¹⁸F) used in conventional nuclear medicine imaging, ⁶⁸Ga has lower spatial resolution and relatively higher Signal to Background Ratio (SBR). Therefore, this study aimed to investigate the optimized parameters and reconstruction methods for PET/CT imaging using the ⁶⁸Ga radiotracer through model-based image evaluation. Materials and Methods: Based on clinical images of ⁶⁸Ga-PSMA PET/CT, a NEMA/IEC 2008 PET phantom model was prepared with a Hot vs Background (H/B) ratio of 10:1. Images were acquired for 9 minutes in list mode using DMIDR (GE, Milwaukee WI, USA). Subsequently, reconstructions were performed for 1 to 8 minutes using OS-EM (Ordered Subset Expectation Maximization) + TOF (Time of Flight) + Sharp IR (VPFX-S), and BSREM (Block Sequential Regularized Expectation Maximization) + TOF + Sharp IR (QCFX-S-400), followed by comparative evaluation. Based on the previous experimental results, images were reconstructed for BSREM + TOF + Sharp IR / 2 minutes (QCFX-S-2min) with varying β-strength values from 100 to 700. The image quality was evaluated using AMIDE (freeware, Ver.1.0.1) and Advanced Workstation (GE, USA). Results: Images reconstructed with QCFX-S-400 showed relatively higher values for SNR (Signal to Noise Ratio), CNR (Contrast to Noise Ratio), count, RC (Recovery Coefficient), and SUV (Standardized Uptake Value) compared to VPFX-S. SNR, CNR, and SUV exhibited the highest values at 2 minutes/bed acquisition time. RC showed the highest values for a 10 mm sphere at 2 minutes/bed acquisition time. For small spheres of 10 mm and 13 mm, an inverse relationship between β-strength increase and count was observed. SNR and CNR peaked at β-strength 400 and then decreased, while SUV and RC exhibited a normal distribution based on sphere size for β-strength values of 400 and above. Conclusion: Based on the experiments, PET/CT imaging using the ⁶⁸Ga radiotracer yielded the most favorable quantitative and qualitative results with a 2 minutes/bed acquisition time and BSREM reconstruction, particularly when applying β-strength 400. The application of BSREM can enhance accurate quantification and image quality in ⁶⁸Ga PET/CT imaging, and an optimization process tailored to each institution's imaging objectives appears necessary.

• The Journal of the Petrological Society of Korea
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• v.7 no.2
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• pp.111-131
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• 1998

The migmatitic gneiss in the Odesan Gneiss Complex has small amount of quartzite, amphibolite and marble and the Kuryong Group which contact with migmatitic gneiss unconformitly, also contains some amphibolite. Preview studies of this area had regarded that the amphibolites contact with marble had been produced by metasomatism from the pelitic and calcareous sediments mixtures, but the amphibolite is reinterpreted as igneous origin. $SiO_2$ content of the amphibolite is 45.9~52.7 wt%, which corresponds to basaltic composition. MgO content has narrow range (4.6~6.87 wt%) and major and trace element are plotted against MgO,$TiO_2, P_2O_5$, Hf, Zr are reduced and Cr and Ni are increased their content with increasing MgO. This phenomenon indicates that the basaltic magma as the protolith of the amphibolite had frationated with the crystallization of the pyroxene and/or olivine. REE pattern has smoothly decrease from LREE to HREE. Eu/Eu(0.83~1.19) show the flat Eu anomaly, which indicate small fractional crystallization of plagioclase. HREE is enriched in the garnet-bearing amphibolites. Several discrimination diagram for the basaltic magma show that the amphibolite of the study area is originated tholeiitic basaltic magma indicating continental rift environment. Due to determine the metamorphic condition garnet-hornblende geothermometry and hornblende-plagioclase geobarometry are used. Peak metamorphic temperature range of the amphibolite $788~870^{\circ}C$ and is deduced toward the northeastern part. The calculated temperature from the amphibolite has slightly higher than the temperature of the metapelites but the trend of metamorphic grade which decrease from western to eastern part progradly is similar to each other. The metamorphic pressure calculated by garnet- hornblede-plagioclase geobarometry is 4~5kb. But ilmenite-plagioclase pair enclosed in garnet show 8 kb at $700^{\circ}C$ by garnet-ilmenite-rutile-plagioclase geobarometery. The zonal profile of garnet in sample 84 shows the bell-shape profile, which grossular content decreases whereas pyrope content increases progressively. This means that the amphibolite has undergone the clockwise P-T-t path which is shown in the migmatitic gneiss of the Odesan Gneiss Complex.

• Applied Biological Chemistry
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• v.16 no.2
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• pp.99-111
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• 1973

Percentage recovery or fertilizer nitrogen, phosphorus and potassium by rice plant(Oriza sativa L.) were investigated at 8, 10, 12, 14 kg/10a of N, 6 kg of $P_2O_5$ and 8 kg of $K_2O$ application level in 1967 (51 places) and 1968 (32 places). Two types of nutrient contribution for the yield, that is, P type in which phosphorus firstly increases silicate uptake and secondly silicate increases nitrogen uptake, and K type in which potassium firstly increases P uptake and secondly P increases nitrogen uptake were postulated according to the following results from the correlation analyses (linear) between percentage recovery of fertilizer nutrient and grain or dry matter yields and nutrient uptake. 1. Percentage frequency of minus or zero recovery occurrence was 4% in nitrogen, 48% in phosphorus and 38% in potassium. The frequency distribution of percentage recovery appeared as a normal distribution curve with maximum at 30 to 40 recovery class in nitrogen, but appeared as a show distribution with maximum at below zero class in phosphorus and potassium. 2. Percentage recovery (including only above zero) was 33 in N (above 10kg/10a), 27 in P, 40 in K in 1967 and 40 in N, 20 in P, 46 in Kin 1968. Mean percentage recovery of two years including zero for zero or below zero was 33 in N, 13 in P and 27 in K. 3. Standard deviation of percentage recovery was greater than percentage recovery in P and K and annual variation of CV (coefficient of variation) was greatest in P. 4. The frequency of significant correlation between percentage recovery and grain or dry matter yield was highest in N and lowest in P. Percentage recovery of nitrogen at 10 kg level has significant correlation only with percentage recovery of P in 1967 and only with that of potassium in 1968. 5. The correlation between percentage recovery and dry matter yield of all treatments showed only significant in P in 1967, and only significant in K in 1968, Negative correlation coefficients between percentage recovery and grain or dry matter yield of no or minus fertilizer plots were shown only in K in 1967 and only in P in 1968 indicating that phosphorus fertilizer gave a distinct positive role in 1967 but somewhat' negative role in 1968 while potassium fertilizer worked positively in 1968 but somewhat negatively in 1967. 6. The correlation between percentage recovery of nutrient and grain yield showed similar tendency as with dry matter yield but lower coefficients. Thus the role of nutrients was more precisely expressed through dry matter yield. 7. Percentage recovery of N very frequently had significant correlation with nitrogen uptake of nitrogen applied plot, and significant negative correlation with nitrogen uptake of minus nitrogen plot, and less frequently had significant correlation with P, K and Si uptake of nitrogen applied plot. 8. Percentage recovery of P had significant correlation with Si uptake of all treatments and with N uptake of all treatments except minus phosphorus plot in 1967 indicating that phosphorus application firstly increases Si uptake and secondly silicate increases nitrogen uptake. Percentage recovery of P also frequently had significant correlation with P or K uptake of nitrogen applied plot. 9. Percentage recovery of K had significant correlation with P uptake of all treatments, N uptake of all treatments except minus phosphorus plot, and significant negative correlation with K uptake of minus K plot and with Si uptake of no fertilizer plot or the highest N applied plot in 1968, and negative correlation coefficient with P uptake of no fertilizer or minus nutrient plot in 1967. Percentage recovery of K had higher correlation coefficients with dry matter yield or grain yield than with K uptake. The above facts suggest that K application firstly increases P uptake and secondly phosphorus increases nitrogen uptake for dry matter yied. 10. Percentage recovery of N had significant higher correlation coefficient with grain yield or dry matter yield of minus K plot than with those of minus phosphorus plot, and had higher with those of fertilizer plot than with those of minus K plot. Similar tendency was observed between N uptake and percentage recovery of N among the above treatments. Percentage recovery of K had negative correlation coefficient with grain or-dry matter yield of no fertilizer plot or minus nutrient plot. These facts reveal that phosphorus increases nitrogen uptake and when phosphorus or nitrogen is insufficient potassium competatively inhibits nitrogen uptake. 11. Percentage recovery of N, Pand K had significant negative correlation with relative dry matter yield of minus phosphorus plot (yield of minus plot x 100/yield of complete plot; in 1967 and with relative grain yield of minus K plot in 1968. These results suggest that phosphorus affects tillering or vegetative phase more while potassium affects grain formation or Reproductive phase more, and that clearly show the annual difference of P and K fertilizer effect according to the weather. 12. The correlation between percentage recovery of fertilizer and the relative yield of minus nutrient plat or that of no fertilizer plot to that of minus nutrient plot indicated that nitrogen is the most effective factor for the production even in the minus P or K plot. 13. From the above facts it could be concluded that about 40 to 50 percen of paddy fields do rot require P or K fertilizer and even in the case of need the application amount should be greatly different according to field and weather of the year, especially in phosphorus.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.152-160
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• 2005

This study was carried out to investigate selectable criteria in evaluating waxy corn $F_1$ hybrids for developing good eating quality waxy corn variety. The physicochemical property analysis of 6 waxy corn $F_1$ hybrids - Chalok1, Chalok2, Heugjeomchal, Yeonnongl, Chalok4, and Suwon45- showed a range of $11.2\~13.1\%$ for crude protein, $5.1\~6.0\%$ for crude fat, $91.8\~92.6\%$ for amylopectin, and $4.5\~6.6\%$ for free sugar content. The pericarp thickness which is one of the most important characteristics related to tenderness in waxy corn was ranged $34\~47{\mu}m$ in 4 waxy corn hybrids - Yeonnongl, Chalok4, Suwon45, and Heugjeomchal. On the other hand, it was ranged $64\~81{\mu}m$ in Chalok1 and Chalok2. The amylogram analysis by rapid visco analyzer showed that in fresh waxy corn hybrid (DAP25), all amylogram properties except setback were higher in Yeonnongl, Chalok4, and Suwon45 compared to those of Chalokl, Chnlok2, and Heugjeomchal. However, in matured waxy corn hybyids (DAP45), the result was the opposite - the amylogram properties were higher in Chalokl, Chalok2, and Heugjeomchal than those of Yeonnongl, Chalok4, and Suwon45. The texture analysis showed that gumminess, chewiness, and hardness increased dramatically with the time after the cooking in Chalokl and Beugjeomchal. On the other hand, these above pyoperties did not change as rapidly with the time in Yeonnongl, Chalok4, and Suwon45. Gumminess, chewiness, and hardness did not increase much within 6 hours after steamingr but increased significantly 32 hours after steaming. Therefore, we have reached a conclusion that texture analysis of cooked waxy corn should be carried out 6 hours after steaming. In the sensory evaluation, Yeonnongl, Chalok4, and Suwon45 revealed higher palatability -6.8, 7.1, and 6.9 respectively - than. that of Chnlokl, Chalok2, and Heugjeomchal. The palatability analysis of 6 waxy corn hybrids showed palatability positively correlating with free sugar content,100-kernel weight, kernel length, kernet width, and consistency, but negatively correlating with pericarp thickness, hardness, gumminess, and chewiness.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.529-541
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• 1999

In order to elucidate characteristics of water quality, investigation of monthly dynamics of environmental factors and algal populations at major four stations of the mid and lower part in Taechong Reservoir was performed from June 1998 to June 1999. Water temperature, DO and pH were ranged 5.3~27.7$^{\circ}C$, 6.2~13.8 mgO$_2$/1 and 6.4~9.5, respectively. Those were varying as the season changes. Among inorganic nitrogen nutrients, NH$_4$was ranged from 5.5% to 7.2% of NO$_3$and NO$_3$was almost same through the seasons except summer in which it was low. SRP and SRSi were increased in summer when the blue-green algae became dominant. Those were decreased as the cell density of diatom increased when the water temperature dropped. Therefore SRSi was considered to be another important nutrient factor contributing to the increment of biomass of freshwater algae as well as SRP. Average chi-$\alpha$ concentration ranged from s to 12 $\mu$g/1 and in the lower part or the reservoir, the lowest was found. Moreover, there were remarkable increment in summer when TN/TP ratio were decreasing from relationships between TN/TP ratio and chi-$\alpha$ concentration. Annual mean ratio of TN/TP ratio was relatively high as the value was 110, which was relatively high, and it showed that P is the dominant factor in the algal growth. The dynamics of phytoplankton were simply dominated by a few species seasonally. In summer, blue -green algae such as Anabaena, Microcystis and Oscillatoria were dominant and algal bloom of blue -green began from early summer, sustained to late autumn. The average standing crops of A. spiroides v. crassa, M. aeruginosa and O. limosa were ranged 0.3~2.0$\times$10$^4$cells/ml, 6.4$\times$10$^2$~1.0$\times$10$^4$cells/ml and 4.6$\times$10$^3$~1.6$\times$10$^4$cells/ml, respectively. In winter, diatom Stephanodiscus was considered to be an important species whose average standing crops of Stephunodiscus was 4.9$\times$10$^2$cells/ml from November to April of the next year and the highest was 1.3$\times$10$^3$cells/ml in January.

• Microbiology and Biotechnology Letters
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• v.43 no.2
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• pp.105-111
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• 2015

An alginate degrading enzyme from the Vibrio crassostreae PKA 1002 strain was used to hydrolyze the water extract of Sargassum thunbergii. To obtain the optimum degrading conditions for the S. thunbergii water extract, the mixture of the water extract and enzyme was incubated at 30℃ for 0, 3, 6, 12, and 24 h, and its alginate degrading ability was measured by reducing sugar and viscosity. A temperature of 30℃ for a period of 6 h was found to be the optimal condition for the enhancement of the alginate’s degrading ability. The pH of the enzymatic hydrolysate was not significantly different from that of the water extract. Overall lightness decreased, but redness and yellowness increased after enzymatic hydrolysis. Total phenolic compounds did not differ between the water extract and the enzymatic hydrolysate. DPPH radical scavenging activity and the reducing power of the enzymatic hydrolysate were lower than those of the water extract. However, the chelating effect of the enzymatic hydrolysate (80.08% at 5 mg/ml) was higher than that of the water extract (62.29%). These results indicate that the enzymatic hydrolysate possesses an anti-oxidant activity by way of the action of the chelating effect.

• Macromolecular Research
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• v.16 no.7
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• pp.575-585
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• 2008

There are two beamlines (BLs), 4C1 and 4C2, at the Pohang Accelerator Laboratory that are dedicated to small angle X-ray scattering (SAXS). The 4C1 BL was constructed in early 2000 and is open to public users, including both domestic and foreign researchers. In 2003, construction of the second SAXS BL, 4C2, was complete and commissioning and user support were started. The 4C2 BL uses the same bending magnet as its light source as the 4C1 BL. The 4C1 BL uses a synthetic double multilayer monochromator, whereas the 4C2 BL uses a Si(111) double crystal monochromator for both small angle and wide angle X-ray scattering. In the 4C2 BL, the collimating mirror is positioned behind the monochromator in order to enhance the beam flux and energy resolution. A toroidal focusing mirror is positioned in front of the monochromator to increase the beam flux and eliminate higher harmonics. The 4C2 BL also contains a digital cooled charge coupled detector, which has a wide dynamic range and good sensitivity to weak scattering, thereby making it suitable for a range of SAXS and wide angle X-ray scattering experiments. The general performance of the 4C2 BL was initially tested using standard samples and further confirmed by the experience of users during three years of operation. In addition, several grazing incidence X-ray scattering measurements were carried out at the 4C2 BL.

• Clinical and Experimental Reproductive Medicine
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• v.36 no.2
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• pp.111-119
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• 2009

Objective: The aim of this study was to compare the clinical efficacy of clomiphene citrate (CC) and letrozole combined with gonadotropins for controlled ovarian stimulation (COS) in patients with CC-induced thin endometrium Methods: Fifty-one intrauterine insemination cycles performed in patients who previously had a thin endometrium (<8 mm) to ovulation induction using CC were included in this study. A CC 100 mg/day (CC+gonadotropin group, n=26) or letrozole 2.5 or 5 mg/day (letrozole+gonadotropin group, n=25) was administered on day 3~7 of the menstrual cycle, combined with gonadotropins at dose 75~150 IU every other day starting on day 5~7. We compared total dose of gonadotropin used, endometrial thickness, endometrial pattern, number of follicles ${\geq}14\;mm$ on hCG day, pregnancy rate and multiple pregnancy rate between the two groups, which were statistically analyzed using Mann-Whitney U test or Fisher's exact test, where appropriate. Results: There were no significant differences in clinical characteristics such as age, duration of infertility, number of previous IUI cycles, basal serum hormone levels and cause of infertility between the two groups. In both groups, the endometrium was significantly thicker than that of previous ovulation induction cycles using CC. No significant differences were found in the total dose of gonadotropin used, day of hCG administration, the rate of triple endometrium and pregnancy rate. The number of follicles ${\geq}14\;mm$ was significantly lower ($3.7{\pm}1.7$ vs. $2.8{\pm}1.7$, p=0.03) and the endometrium on hCG day was significantly thicker ($7.7{\pm}1.5$ vs. $9.1{\pm}1.7$, p=0.001) in letrozole+gonadotropin group compared to CC+gonadotropin group. Conclusion: The clomiphene citrate and letrozole combined with gonadotropins appear to avoid the undesirable effects on the endometrium frequently seen with CC for ovulation induction. However, in terms of adequate endometrial development or optimal follicular growth, letrozole may be more beneficial than CC for gonadotropin-combined COS in patients with CC-induced thin endometrium. Further prospective randomized controlled studies in a larger scale will be necessary to confirm our findings.