• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1393-1398
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• 2018

In conventional single-photon emission computed tomography (SPECT), only the photoelectric events in the detectors are used for image reconstruction. However, if the $^{131}I$ isotope, which emits high-energy radiations (364, 637, and 723 keV), is used in nuclear medicine, both photoelectric and Compton scattering events can be used for image reconstruction. The purpose of our work is to perform simulations for Compton SPECT by using the Geant4 application for tomographic emission (GATE). The performance of Compton SPECT is evaluated and compared with that of conventional SPECT. The Compton SPECT unit has an area of $12cm{\times}12cm$ with four gantry heads. Each head is composed of a 2-cm tungsten collimator and a $40{\times}40$ array of CdZnTe (CZT) crystals with a $3{\times}3mm^2$ area and a 6-mm thickness. Compton SPECT can use not only the photoelectric effect but also the Compton scattering effect for image reconstruction. The correct sequential order of the interactions used for image reconstruction is determined using the angular resolution measurement (ARM) method and the energies deposited in each detector. In all the results of simulations using spherical volume sources of various diameters, the reconstructed images of Compton SPECT show higher signal-to-noise ratios (SNRs) without degradation of the image resolution when compared to those of conventional SPECT because the effective count for image reconstruction is higher. For a Derenzo-like phantom, the reconstructed images for different modalities are compared by visual inspection and by using their projected histograms in the X-direction of the reconstructed images.

• Journal of Radiation Protection and Research
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• 제47권3호
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• pp.143-151
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• 2022

Background: After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, biological alterations in the natural biota, including morphological changes of fir trees in forests surrounding the power plant, have been reported. Focusing on the terminal buds involved in the morphological formation of fir trees, this study developed a method for estimating the absorbed radiation dose rate using radionuclide distribution measurements from tree organs. Materials and Methods: A phantom composed of three-dimensional (3D) tree organs was constructed for the three upper whorls of the fir tree. A terminal bud was evaluated using Monte Carlo simulations for the absorbed dose rate of radionuclides in the tree organs of the whorls. Evaluation of the absorbed dose targeted ¹³¹I, ¹³⁴Cs, and ¹³⁷Cs, the main radionuclides subsequent to the FDNPP accident. The dose contribution from each tree organ was calculated separately using dose coefficients (DC), which express the ratio between the average activity concentration of a radionuclide in each tree organ and the dose rate at the terminal bud. Results and Discussion: The dose estimation indicated that the radionuclides in the terminal bud and bud scale contributed to the absorbed dose rate mainly by beta rays, whereas those in 1-year-old trunk/branches and leaves were contributed by gamma rays. However, the dose contribution from radionuclides in the lower trunk/branches and leaves was negligible. Conclusion: The fir tree model provides organ-specific DC values, which are satisfactory for the practical calculation of the absorbed dose rate of radiation from inside the tree. These calculations are based on the measurement of radionuclide concentrations in tree organs on the 1-year-old leader shoots of fir trees. With the addition of direct gamma ray measurements of the absorbed dose rate from the tree environment, the total absorbed dose rate was estimated in the terminal bud of fir trees in contaminated forests.

• 한국전문물리치료학회지
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• 제28권2호
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• pp.123-131
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• 2021

Background: Only 2% of falls in older adults result in serious injuries (i.e., hip fracture). Therefore, it is important to differentiate injurious versus non-injurious falls, which is critical to develop effective interventions for injury prevention. Objects: The purpose of this study was to a. extract the best features of surface electromyography (sEMG) for classification of injurious falls, and b. find a best model provided by data mining techniques using the extracted features. Methods: Twenty young adults self-initiated falls and landed sideways. Falling trials were consisted of three initial fall directions (forward, sideways, or backward) and three knee positions at the time of hip impact (the impacting-side knee contacted the other knee ("knee together") or the mat ("knee on mat"), or neither the other knee nor the mat was contacted by the impacting-side knee ("free knee"). Falls involved "backward initial fall direction" or "free knee" were defined as "injurious falls" as suggested from previous studies. Nine features were extracted from sEMG signals of four hip muscles during a fall, including integral of absolute value (IAV), Wilson amplitude (WAMP), zero crossing (ZC), number of turns (NT), mean of amplitude (MA), root mean square (RMS), average amplitude change (AAC), difference absolute standard deviation value (DASDV). The decision tree and support vector machine (SVM) were used to classify the injurious falls. Results: For the initial fall direction, accuracy of the best model (SVM with a DASDV) was 48%. For the knee position, accuracy of the best model (SVM with an AAC) was 49%. Furthermore, there was no model that has sensitivity and specificity of 80% or greater. Conclusion: Our results suggest that the classification model built upon the sEMG features of the four hip muscles are not effective to classify injurious falls. Future studies should consider other data mining techniques with different muscles.

• 한국수산과학회지
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• 제55권4호
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• pp.431-436
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• 2022

For the safety assessment of microbiological and chemical hazards in katsuobushi, fifteen samples of katsuobushi were purchased from supermarkets. The contamination levels of total viable bacteria, coliforms, Escherichia coli, and nine pathogenic bacteria [Staphylococcus aureus, Salmonella spp., Listeria monocytogenes, Bacillus cereus, Vibrio parahaemolyticus, Clostridium perfringens, Enterohemorrhagic E. coli (EHEC), Yersinia enterocolitica and Campylobacter jejuni/coli] were quantitatively or qualitatively assessed. Additionally, the heavy metals (total and methyl mercury) content, radioactivity (¹³¹ I, ¹³⁴ Cs⁺ and ¹³⁷ Cs) were quantitatively assessed. Microbial and chemical analyses were performed using standard methods in Korean food code. The contamination level of total viable bacteria was 2.70 (1.18-4.42) log CFU/g. Coliforms, E. coli and S. aureus were not detected in any samples. Other eight pathogenic bacteria were negative in all samples. The contamination levels of total and methyl mercury were 0.366 (0.227-0.481) and 0.120 (0.002-0.241) mg/kg, respectively. In addition, radioactivity was not detected in any samples. The results will be helpful in revitalizing domestic use and boosting exports of katsuobushi because the microbiological and chemical safety of katsuobushi has been assured. Furthermore, the results may be used as a basis for performing chemical and microbial risk assessments of katsuobushi.

• Nuclear Engineering and Technology
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• 제7권3호
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• pp.213-222
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• 1975

알카리로 처리한 국산 blown asphalt를 사용해서 방사성 폐액을 180-20$0^{\circ}C$ 범위 내에서 고화처리한 것이 산처리 한것보다 좋은 결과를 얻었으며, 방사선 조사선량이 4.0$\times$$10^{7}$ rad까지도 안정된 고화체로 존재하고 있다. 한편 40wt%의 고형분이 함유되어 있는 $^{137}$Cs-asphalt 고화체의 증류수에 의한 $^{137}$Cs의 용출율이 8.27$\times$$10^{-4}$ g/$\textrm{cm}^2$-day 인데 반하여 $^{90}$ Sr은 낮았으며, 일반적으로 증류수보다 해수때가 또한 pH가 증가함에 따라 용출율은 낮아진다.

• 대한방사성의약품학회지
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• 제7권2호
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• pp.79-84
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• 2021

Radiopharmaceuticals are important for tumor diagnosis and therapy. To deliver a radiotracer at the desired target excluding non-targeted tissues is difficult The development of a targeted tracer that has a good clearance profile while maintaining high biostability and biocompatibility is key to optimizing its biodistribution and transport across biological barriers. Improving the hydrophilicity of radiotracers by PEGylation can reduce serum binding, allowing the tracer to circulate without retention and reducing its affinity for non-targeted tissues. In this study, we synthesized a new benzamido tracer (SnBz-PEG₃₆) with the introduction of a low molecular weight polyethylene glycol unit (PEG₃₆, ~2,100 Da). The tumor targeting efficiency and biodistribution of [¹³¹I]-Bz-PEG₃₆ or radiotracer-loaded liposomes were evaluated after their administration to normal mice or mouse tumor models including CT26 (xenograft) and 4T1 (xenograft and orthotopic). Most of the radiotracer was cleared out rapidly (1-24 h post-administration) through the kidney and there was little tumor uptake.

• 대한방사성의약품학회지
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• 제9권1호
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• pp.23-33
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• 2023

Prostate cancer ranks as the world's second most frequently diagnosed cancer among men, and is responsible for the fifth highest number of cancer-related deaths in this population. The development of effective diagnostic and therapeutic approaches for prostate cancer remains a major challenge in the field of oncology. Over the past few years, the prostate-specific membrane antigen (PSMA) has raised as a hopeful tracer for the diagnosis and treatment of prostate cancer.Various radioisotopes, such as ¹³¹I, ^99mTc, ⁶⁸Ga, and ¹⁷⁷Lu, have been used to label PSMA analogues, with varying degrees of success. Among these, ⁶⁸Ga-PSMA-11 and ¹⁷⁷Lu-PSMA-617 have emerged as the most promising radioligands for clinical use. Recently, researchers have been exploring the use of other radioisotopes, such as ²¹¹At, ⁸⁹Zr, ^64/67Cu, and ^203/212Pb, for the labeling of PSMA-targeted radioligands. These radioisotopes have unique properties that may offer advantages over existing radioligands, such as longer half-lives, higher specific activities, and different emission profiles. Efforts are currently underway to develop these radiopharmaceuticals and make them more widely available for clinical use. These exciting developments highlight the potential of PSMA-targeted radioligands for the diagnosis and treatment of prostate cancer, and provided significant implications for the management of this disease in the future. The current study aims to provide a comprehensive summary of the latest research and clinical applications of radiolabeled PSMA inhibitors for diagnoses and therapy of prostate cancer, emphasizing the exciting developments in the field and their potential impact on clinical practice.

• 열처리공학회지
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• 제36권5호
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• pp.270-276
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• 2023

In this study, we analyzed two types of cold forging dies commonly used for manufacturing general nuts and screws to investigate the differences in WC powder according to the lifespan. For both Type I and Type II dies, it was observed that as the lifespan of the molds increases, the area fraction of Co becomes larger and the size of the powder becomes smaller. Moreover, there is a trend where the strength also increases as the lifespan gets longer. Actually, the hardness value of the sample with the longest lifespan is ~ 131 HV higher than the specimen of the shortest lifespan, It is noted that the reduction in toughness of the WC-Co mold is caused by insufficient Co and the decrease in contact surface area of WC-Co results in a reduced bonding surface area. The lifespan of cold-working WC molds increases when the W content and the volume fraction of WC are high, and the size of the WC powder is small. The results can significantly enhance producing high-quality molds with an extended lifespan using WC powder for cold forging.

• Journal of Microbiology and Biotechnology
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• 제33권6호
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• pp.806-822
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• 2023

In the current study we assessed a new crystallized compound, 5-(1-hydroxybutyl)-4-methoxy-3-methyl-2H-pyran-2-one (C-HMMP), from the endophytic fungus Colletotrichum acutatum residing in the medicinal plant Angelica sinensis for its in vitro antimicrobial, antibiofilm, antioxidant, antimalarial, and anti-proliferative properties. The promising compound was identified as C-HMMP through antimicrobial-guided fraction. The structure of C-HMMP was unambiguously confirmed by 2D NMR and HIRS spectroscopic analysis. Antimicrobial property testing of C-HMMP showed it to be effective against a variety of pathogenic bacteria and fungi with MICs ranging from 3.9 to 31.25 ㎍/ml. The compound displayed excellent antibiofilm activity against C. albicans, S. aureus, and K. pneumonia. Furthermore, the antimalarial and radical scavenging activities of C-HMMP were clearly dosedependent, with IC50 values of 0.15 and 131.2 ㎍/ml. The anti-proliferative activity of C-HMMP against the HepG-2, HeLa, and MCF-7 cell lines in vitro was investigated by MTT assay, revealing notable anti-proliferative activity with IC50 values of 114.1, 90, and 133.6 ㎍/ml, respectively. Moreover, CHMMP successfully targets topoisomerase I and demonstrated beneficial anti-mutagenicity in the Ames test against the reactive carcinogenic mutagen, 2-aminofluorene (2-AF). Finally, the compound inhibited the activity of α-glucosidase and α-amylase with IC50 values of 144.7 and 118.6 ㎍/ml, respectively. To the best of our knowledge, the identified compound C-HMMP was obtained for the first time from C. acutatum of A. sinensis, and this study demonstrated that C-HMMP has relevant biological significance and could provide better therapeutic targets against disease.

• 운동영양학회지
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• 제13권2호
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• pp.131-140
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• 2009

The aim of this study was to investigate the expression of PPAR-α, -β/δ, -γ, PGC-1α, GLUT-4 and p-AMPK-α₂ protein in the skeletal muscle of diabetic induced-rats by endurance training combined with rosiglitazone. The expression of PPAR-α, -β/δ, -γ, PGC-1α, GLUT-4 and p-AMPK-α₂ protein in red and white gastrocnemius by western blotting. The body weight was higher in diabetic induced-rats compared to the normal rats and after the treatment of exercise combined with rosiglitazone was significantly reduced in the all group. The levels of blood glucose was higher in diabetic induced-rats compared to the normal rats and after the treatment of exercise combined with rosiglitazone was significantly reduced in the all group. The expression of PPAR-α, -γ, PGC-1α in skeletal muscle of diabetic induced-rats were increased all groups and increased significantly in the group with exercise combined with rosiglitazone. The expression of GLUT-4 and p-AMPK-α₂ protein in the skeletal muscle of diabetic induced-rats were increased all groups and increased significantly in the group with exercise combined with rosiglitazoneI. These results suggest that exercise training and rosiglitazone may act as complementary therapies for the treatment of insulin rasistance.