• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.2
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• pp.62-72
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• 2017

Spatio-temporal projection of evapotranspiration over croplands would be useful for assessment of climate change impact and development of adaptation strategies in agriculture. Potential evapotranspiration (PET) and dryness index (DI) during rice growing seasons were calculated using climate change scenario data provided by the National Institute of Meteorological Research (NIMR). A data processing tool for gridded climate data files, readGrADSWrapper, was used to calculate PET and DI during the current (1986-2005) and future (2006-2100) periods. Scripts were written to implement the formulas of PET and DI in R, which is an open source statistical data analysis tool. Evapotranspiration in rice fields ($PET_{Rice}$) was also determined using R scripts. The Spatio-temporal patterns of PET differed by regions in Korean Peninsula under current and future climate conditions. Overall, PET and $PET_{Rice}$ tended to increase throughout the $21^{st}$ century. Those results suggested that region-specific water resource managements would be needed to minimize the risk of water loss in the regions where considerable increases in PET would occur under the future climate conditions. For example, a number of provinces classified as a humid region were projected to become a sub-humid region in the future. The Spatio-temporal assessment of water resources based on PET and DI would help the development of climate change adaptation strategies for rice production in the 21st century. In addition, the studies on climate change impact would be facilitated using specialized data tools, e.g., readGrADSWrapper, for geospatial analysis of climate data.

• Radiation Oncology Journal
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• v.32 no.1
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• pp.31-42
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• 2014

Purpose: To evaluate the usefulness of positron emission tomography/computed tomography (PET/CT) for field modification during radiotherapy in esophageal cancer. Materials and Methods: We conducted a retrospective study on 33 patients that underwent chemoradiotherapy (CRT). Pathologic findings were squamous cell carcinoma in 32 patients and adenocarcinoma in 1 patient. All patients underwent PET/CT scans before and during CRT (after receiving 40 Gy and before a 20 Gy boost dose). Response evaluation was determined by PET/CT using metabolic tumor volume (MTV), total glycolytic activity (TGA), MTV ratio (rMTV) and TGA ratio (rTGA), or determined by CT. rMTV and rTGA were reduction ratio of MTV and TGA between before and during CRT, respectively. Results: Significant decreases in MTV ($MTV_{2.5}$: mean 70.09%, p < 0.001) and TGA ($TGAV_{2.5}$: mean 79.08%, p < 0.001) were found between before and during CRT. Median $rMTV_{2.5}$ was 0.299 (range, 0 to 0.98) and median $rTGAV_{2.5}$ was 0.209 (range, 0 to 0.92). During CRT, PET/CT detected newly developed distant metastasis in 1 patient, and this resulted in a treatment strategy change. At a median 4 months (range, 0 to 12 months) after completion of CRT, 8 patients (24.2%) achieved clinically complete response, 11 (33.3%) partial response, 5 (15.2%) stable disease, and 9 (27.3%) disease progression. $SUV_{max}$ (p = 0.029), $rMTV_{50%}$ (p = 0.016), $rMTV_{75%}$ (p = 0.023) on intra-treatment PET were found to correlate with complete clinical response. Conclusion: PET/CT during CRT can provide additional information useful for radiotherapy planning and offer the potential for tumor response evaluation during CRT. $rMTV_{50%}$ during CRT was found to be a useful predictor of clinical response.

• Transactions of Materials Processing
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• v.23 no.1
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• pp.5-9
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• 2014

Although much research has been conducted to reduce the thickness of PET bottles in order to save manufacturing costs, the challenge remains of guaranteeing mechanical strength for top-loaded thin PET bottles. The current study investigates the large deformation characteristics of a circle shaped PET bottle and a square shaped PET bottle when compressively loaded using FEA. The arc length method is used in the nonlinear FEA to understand the buckling phenomenon. For PET bottles with the same capacity, the circle shaped bottle shows more resistance to buckling and compression loading than the square shaped bottle.

• Korean Journal of Materials Research
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• v.18 no.1
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• pp.32-37
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• 2008

The electrical, optical, structural and surface properties of an indium tin oxide (ITO) film grown on a flexible PET substrate using a specially designed roll-to-roll (R2R) sputtering system as a function of the DC power, $Ar/O_2$ flow ratio, and rolling speed is reported. It was observed that both the electrical and optical properties of the ITO film on the PET substrate were critically dependent on the $Ar/O_2$ flow ratio. In addition, x-ray diffraction examination results showed that the structure of the ITO film on the PET substrate was an amorphous structure regardless of the DC power and the $Ar/O_2$ flow ratio due to a low substrate temperature, which was maintained constant by a main cooling drum. Under optimized conditions, ITO film with resistivity of $6.44{\times}10^{-4}{\Omega}-cm$ and transparency of 86% were obtained, even when prepared at room temperature. Furthermore, bending test results exhibited that R2R-grown ITO film had good flexibility which would be applicable to flexible displays and solar cells.

• Journal of the Korean Society of Radiology
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• v.12 no.5
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• pp.575-582
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• 2018

This article compared accuracy of 5 types of radionuclide activity meters that are being used in medical institutions and proposed the correction factor for each radionuclide activity meters type, using Ge-68/Ga-68 radiation sources for scanner setting, regular scanner correction, attenuation correction, and normalization. The calibration constant between baseline values and measured values by CRC-15R, CRC-15 PET, CRC-712M, CRC-15 Beta, and CRC-25PET was 0.99999(P<0.0001), which showed very high linearity. In the accuracy test, CRC-15R, CRC-15 PET, CRC-712M, CRC-15 Beta, and CRC-25PET model showed -3.232%, -1.342%, -2.815%, -2.913%, and -3.089% respectively.

• The Korean Journal of Nuclear Medicine
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• v.39 no.1
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• pp.49-56
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• 2005

Purpose: Dedicated animal PET is useful equipment for the study of new PET tracer. recently, microPET R4 was installed in the Korea institute of radiology and medical science. In this study, we measured the characteristics of scanner. Materials and methods: Resolution was measured using a line source (F-18:65 ${\mu}Ci$, inner diameter: 0.5 mm). The line source was put in the axial direction and was moved from the center of field of view to outside with 1 mm interval. PET images were reconstructed using a filtered back-protection and ordered subset expectation maximization. line source (16.5 ${\mu}Ci$, 78 mm) was put on the tenter of axial direction to measure the sensitivity when the deadtime was under 1%. Images were acquired during 4 minutes respectively from center to 39 mm outward. Delayed count was subtracted from total count and then decay was corrected for the calculation of sensitivity. Noise equivalent count ratio and scatter fraction were calculated using cylindrical phantom. Results: Spatial resolution of reconstructed image using filtered back-projection was 1.86 mm(radial), 1.95 mm(tangential), 1.95 mm(axial) in the tenter of field of view, and 2.54 mm, 2.8 mm, 1.61 mm in 2 cm away from the center respectively. Sensitivity was 2.36% at the center of transaxial field of view. Scatter fraction was 20%. Maximal noise equivalent count ratio was 66.4 kcps at 242 kBq/mL. Small animal images were acquired for confirmation of performance. Conclusion: Performance characteristics of microPET R4 were similar with reported value. So this will be a useful tool for small animal imaging.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.1
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• pp.98-104
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• 2009

The objective of this study was to characterize quality changes of PET-packaged green tea beverage during 4-week storage at $60^{\circ}C$. Changes in oxygen transmission of the PET bottle package and cap removal torque were also examined. MXD6 blend PET bottle showed stability in the gas barrier. Its cap removal torque was kept stable during the 4 weeks. pH, color value, contents of vitamin C and catechin showed significant changes during the storage while caffeine and amino acid did not change significantly. Four alcohol flavor components (hexanol, linalool, menthol, and ${\alpha}$-terpineol) increased rapidly during the first three weeks while d-limonene did not show significant change. Sensory test showed decrease in astringent flavor lowering the product flavor and acceptability.

• Journal of Gastric Cancer
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• v.17 no.4
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• pp.384-393
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• 2017

Purpose: The tumor microenvironment is known to be associated with the metabolic activity of cancer cells and local immune reactions. We hypothesized that glucose metabolism measured by 2-deoxy-2-($^{18}F$)fluoro-D-glucose ($^{18}F-FDG$) positron emission tomography (PET)-computed tomography (CT) ($^{18}F-FDG$ PET-CT) would be associated with local immune responses evaluated according to the presence of tumor infiltrating lymphocytes (TILs). Materials and Methods: We retrospectively reviewed 56 patients who underwent $^{18}F-FDG$ PET-CT prior to gastrectomy. In resected tumor specimens, TIL subsets, including cluster of differentiation (CD) 3, CD4, CD8, Forkhead box P3 (Foxp3), and granzyme B, were subjected to immunohistochemical analysis. The prognostic nutritional index (PNI) was calculated as: ($10{\times}serum$ albumin value)+($0.005{\times}peripheral$ lymphocyte counts). Additionally, the maximum standard uptake value ($SUV_{max}$) was calculated to evaluate the metabolic activity of cancer cells. Results: The $SUV_{max}$ was positively correlated with larger tumor size (R=0.293; P=0.029) and negatively correlated with PNI (R=-0.407; P=0.002). A higher $SUV_{max}$ showed a marginal association with higher CD3 (+) T lymphocyte counts (R=0.227; P=0.092) and a significant association with higher Foxp3 (+) T lymphocyte counts (R=0.431; P=0.009). No other clinicopathological characteristics were associated with $SUV_{max}$ or TILs. Survival analysis, however, indicated that neither $SUV_{max}$ nor Foxp3 held prognostic significance. Conclusions: FDG uptake on PET-CT could be associated with TILs, especially regulatory T cells, in gastric cancer. This finding may suggest that PET-CT could be of use as a non-invasive tool for monitoring the tumor microenvironment in patients with gastric cancer.

• Progress in Medical Physics
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• v.24 no.1
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• pp.68-75
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• 2013

The purpose of this research is to compare and analyze $SUV_{LBM}$-maximum of normal regions using VOI (the volume of interest) in order to enhance the diagnostic level in whole body images of PET/CT and PET/MRI for 26 health check-up participants. In particular, we try to set up $SUV_{LBM}$-maximum data that can be used in synchronous evaluation for PET/CT and PET/MRI without contrast media. The evaluation of $SUV_{LBM}$-maximum for normal regions of whole body PET/CT and whole body PET/MRI shows that the image of PET/MRI differs very significantly from the reference image of PET/CT (p<0.0001). However, they exhibit high correlations in view of statistics (R>0.8). From this research, we suggest that the decision in the evaluation of $SUV_{LBM}$-maximum for PET/MRI should be made with the reduction of about 26.3%, while one should decide with the reduction of about 29.3% when the contrast media is used. It is helpful to interpret all image of PET/CT and PET/MRI using $SUV_{LBM}$-maximum for convenience and efficiency.

• Textile Coloration and Finishing
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• v.29 no.4
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• pp.239-246
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• 2017

Recently fiber-reinforced thermoplastic composites have attracted great interest from industry and study because they offer unique properties such as high strength, modulus, impact resistance, corrosion resistance, and damping reduction which are difficult to obtain in single-component materials. The demand for plastics is steadily increasing not only in household goods, packaging materials, but also in high-performance engineering plastic and recycling. As a result, the technology of recycling plastic is also attracting attention. In particular, many paper have studied recycling systems based on recycled thermoplastics. In this paper, properties of Glass Fiber Reinforced Thermoplastic(GFRTP) materials were evaluated using recycled PET for injection molding bicycle frame. The effect on thermal and mechanical properties of recycled PET reinforced glass chop fiber according to fiber cross section and fiber content ratio were studied. And it was compared void volume and torque energy by glass fiber cross section, which is round section and flat section. Mechanical characteristics of resulting in GF/rPET has been increased by increasing fiber contents, than above a certain level did not longer increased. And mechanical properties of flat glass fiber reinforced rPET with low void volume were most excellent.