• Journal of Bio-Environment Control
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• v.12 no.3
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• pp.107-113
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• 2003

This study was carried out to improve the performance of pre-developed heat recovery devices attached to exhaust-gas flue connected to combustion chamber of greenhouse heating system. Four different units were compared in the aspect of heat recovery performance; A-, B-, and C-types are exactly the same with the old ones reported in previous studies. D-type newly developed in this experiment is mainly different with the old ones in its heat exchange area and tube thickness. But airflow direction(U-turn) and pipe arrangement are similar with previous three types. The results are summarized as follows; 1. System performances in the aspect of heat recovery efficiency were estimated as 42.2% for A-type, 40.6% for B-type, 54.4% for C-type, and 69.2% for D-type. 2. There was not significant improvement of heat recovering efficiency between two different airflow directions inside the heat exchange system. But considering current technical conditions, straight air flow pattern has more advantage than hair-pin How pattern (U-turn f1ow). 3. The main factors influencing on heat recovery efficiency were presumably verified to be the total area of heat exchange surface, the thickness of ail-flow pipes, and the convective heat transfer coefficient influenced by airflow velocity under the conditions of allowable pipe durability and safety. 4. Desirable blower capacity for each type of heat recovery units were significantly different to each other. Therefore, the optimum airflow capacity should be determined by considering in economic aspect of electricity required together with the optimum heat recovery performance of given heat recovery systems.

• The Korea Journal of Herbology
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• v.32 no.1
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• pp.1-13
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• 2017

Objective : Soybeans of Canavalia gladiata(CG) and root of Arctium lappa(AL) have been reported to have anti-inflammatory, antioxidant effect. However, the immunoregulatory mechanisms of its combinational prescription remain a matter of considerable debate. In the current study, we investigated whether CG and AL and its combinational prescription(CG+AL) regulate immune system using chronic immobilization-stress mouse model. Methods : C57BL/6J mice fixed for 2 hours into immobilization tube after CG, AL, CG+AL oral administration after 2 hours daily for 21 days. After every experiment has ended the C57BL/6J mice were sacrificed on 22 days. The production of Serotonin and Cortisol, lgA were observed by ELISA method, The proportion of immune cells such as T/B cell and macrophage, NK cell were measured by FACS. Then, Real-time PCR was performed to measure the mRNA expression of Inflammatory cytokines(IL-1beta, IL-6, TNF-a) and T cell activation cytokines(IL-2, IL-10, IFN-gamma, IL-12p35 / p40). Result : When chronic immobilization-stress mouse model were treated with CG+AL(1:4), the expression of mRNA were significantly decreased at the Inflammatory cytokines(IL-1beta, IL-6, TNF-a). While, the levels of mRNA were significantly increased at immune T cell activation cytokines. Additionally, CG+AL(1:4) combinational prescription group enhanced immune cells such as T/B cell and macrophage, NK cell. Furthermore, the Immuno-fluorescence result of brain tissue can confirm that CG+AL(1:4) group significantly increased the BDNF expression. Conclusion : These result suggest that CG+AL(1:4) combinational prescription has Immune System enhancement via stress-mediated immunocyte.

• Journal of Radiation Protection and Research
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• v.40 no.2
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• pp.110-117
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• 2015

Recently, Due to the increased industry using radiation inspection equipment in the semiconductor, this demand of technology research is increasing. Although semiconductor inspection equipment is using low energy X-ray from 40 keV to 120 keV, Studies of radiation damage about the low energy X-ray are lacking circumstance in our country. Therefore, It is study that BJT (bipolar junction transistor) of one type of semiconductor elements are received radiation damage by low energy X-ray. BJT were used to the NXP semiconductor company's BC817-25 (NPN type), and Used the X-ray generator for the irradiation. Radiation damage of BJT was evaluated that confirm to analyse change of collector-emitter voltage of before and after X-ray irradiation when current gain fixed to 10. X-ray generator of tube voltage was setting 40 kVp, 60 kVp, 80 kVp, 100 kVp, 120 kVp and irradiation time was setting 180s, 360s, 540s into 180s intervals. As the result, We confirmed radiation damage in BJT by low energy X-ray under 120 keV energy, and Especially the biggest radiation damage was appeared at the 80 kVp. It is expected that ELDRS (enhanced low dose rate sensitivity) phenomenon occurs on the basis of 80 kVp. This studies expect to contribute effective dose administration of semiconductor inspection equipment using low energy X-ray, Also Research and Development of X-ray filter.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.3
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• pp.237-242
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• 2016

The major advantage of slip-ring technology in Spiral CT is that it facilitates continuous rotation of the x-ray tube, so that volume data can be acquired from a patient quickly. Not only for such a fast scan, but also for the dose reduction purpose, high signal-to-noise ratio and fast data acquisition system is required. In this study, we have built a multi-channel photodetector and multi-channel data acquisition system for CT application. The detector module consisted of CdWO4 crystal and Si photodiode in 16 channels. For the performance test of the preamplifier stage, both the transimpedance and switched integrator types are optimized for the photodetector modules. Switched integrator showed better noise performance in the limited bandwidth which is suitable for the current CT application. The control sequence for data acquisition and 20 bit ADC is designed with VHDL(Very High Speed Integrated Circuit Hardware Description Language) and implemented on FPGA(Field Programmable Gate Array) chip. Our Si photodiode detector module coupled to CdWO4 crystal showed comparable signal with other commercially available photodiode for CT. Switched integrator type showed higher SNR but narrower bandwidth compared to transimpedance preamplifier. Digital hardware is designed by FPGA, so that the control signal could be redesigned without hardware alteration.

• Journal of radiological science and technology
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• v.44 no.2
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• pp.101-107
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• 2021

The purpose of this study was to evaluate optimal CT scan parameters to minimize patient dose to the irradiation and maintain satisfactory image quality in low-dose chest computed tomography (CT) scans. In a chest anthropomorphic phantom, chest CT scans were performed at different kVp and mA within reference of 3.4mGy in volume CT Dose Index (CTDI_vol). The following quantitative parameters had been statistically evaluated: image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM). Nine radiographers conducted the blind test to select the optimal kVp-mA combination. Results indicated that the kVp-mA combination of 80kVp-90mA, 100kVp-50mA, 120kVp-30mA and 140kVp-30mA were obtained high SNR and CNR. The 120kVp-30mA combination offered good compromise in the FOM, which showed the quality and dose performance. In the blind test, an image of 80kVp-90mA obtained a high score with 4.7 points, and 120kVp-10mA or 140kVp-10mA with a low tube current were observed severe noise and poor image quality, thus resulting in decreased diagnostic accuracy. On the other hand, in the combination of high kVp and high mA(140kVp-90mA), the image quality was improved, but the radiation dose was also increased. the FOM value of 140kVp-90mA was lower than 120kVp-30mA. The application of appropriate scan parameters in low-dose chest CT scans produced satisfactory results in dose and image quality for the accuracy of the clinical diagnosis.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.5
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• pp.459-466
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• 2021

Cardiovascular disease (CVD) and its complications are the leading cause of morbidity and mortality in the world. Because of the side effects and incomplete recovery from current therapy, stem cell therapy emerges as a potential therapy for CVD treatment, and endothelial progenitor cell (EPC) is one of the key stem cells used for therapeutic applications. The effect of this therapy required the expansion of EPC function. To enhance the EPC activation, proliferation, and angiogenesis using dronedarone hydrochloride (DH) is the purpose of this study. DH received approval for atrial fibrillation treatment and its cardiovascular protective effects were already reported. In this study, DH significantly increased EPC proliferation, tube formation, migration, and maintained EPCs surface marker expression. In addition, DH treatment up-regulated the phosphorylation of AKT and reduced the reactive oxygen species production. In summary, the cell priming by DH considerably improved the functional activity of EPCs, and the use of which might be a novel strategy for CVD treatment.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.445-453
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• 2021

CT scan is reported to have a high risk of cancer due to a relatively high dose among medical radiological examinations. In particular, exposure to radiation to the breast, which is sensitive to radiation, is inevitable during a chest CT scan for female patient. In this study, the dose reduction effect of wearing a compression band during chest CT scans in women was evaluated, and the lifetime attributable risk due to the effective dose exposed during the CT scan was estimated. As a result, when the compression band was used, the effective tube current decreased as the outer perimeter of the chest became smaller, and it was analyzed that the CT dose index and effective dose were also reduced. In addition, the lifetime attributable risk by chest CT scan was found to reduce the cancer risk by 3.2 per 100,000 for all cancers, 0.2 per 100,000 for solid cancer, and 0.8 per 100,000 for breast cancer, based on women in their 30s when using a compression band. It is judged that the risk of cancer can be reduced through the use of appropriate scan parameters and dose optimization measures such as compression bands for future CT examinations.

• Journal of Korean Society on Water Environment
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• v.38 no.2
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• pp.103-112
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• 2022

A gold amalgam voltammetric microelectrode (GAVM) system was developed for the quantification of dissolved biogeochemical species, such as O₂, Fe²⁺, Mn²⁺, and HS^- in sediment porewater. Commercially available Ag/AgCl and platinum electrodes were used as the reference and counter electrode, respectively, and a gold amalgam microelectrode was fabricated in the laboratory using 150-um diameter gold wire and a borosilicate capillary tube with a 1.6-mm diameter. A portable potentiostat (Metrohm, DropSens) was used for the application of voltage sweeping and to acquire the electric current. For sediment profiling, a commercially available actuator was customized and modified. The analysis method used in the system used the most widely used analysis method among the electrochemical analysis currently used The GAVM system was successively calibrated with the species and applied to estuarine sediments. The porewater analysis showed that the oxygen concentration was decreased to zero at a depth of 0.6 mm, and maximum Mn²⁺ and Fe²⁺ concentrations of 50 uM and 20 uM were detected at 2 and 3-cm depths, respectively. Maximum HS^- concentrations of 10 uM were detected at 4 cm in the deeper sediments. The GAVM system was successfully developed and applied to the sediment and can be used to better understand biogeochemical reactions.

• Journal of the Korea Society of Computer and Information
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• v.27 no.3
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• pp.53-61
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• 2022

Recent years have drawn a great attention to generation MZ and Metaverse, due to 4th industrial revolution and the development of digital environment that blurs the boundary between reality and virtual reality. Generation MZ approaches the information very differently from the existing generations and uses distinguished communication methods. In terms of learning, they have different motivations, types, skills and build relationships differently. Meanwhile, Metaverse is drawing a great attention as a teaching method that fits traits of gen MZ. Thus, the current research aimed to investigate how to increase the use of Metaverse in Educational Technology. Specifically, this research examined the antecedents of popularity of Gather Town, a platform of Metaverse. Big data of news articles have been collected and analyzed using the Bigkinds system provided by Korea Press Foundation. The analysis revealed, first, a rapid increasing trend of media exposure of Gather Town since July 2021. This suggests a greater utilization of Gather Town in the field of education after the COVID-19 pandemic. Second, Word Association Analysis and Word Cloud Analysis showed high weights on education related words such as 'remote', 'university', and 'freshman', while words like 'Metaverse', 'Metaverse platform', 'Covid19', and 'Avatar' were also emphasized. Third, Network Analysis extracted 'COVID19', 'Avatar', 'University student', 'career', 'YouTube' as keywords. The findings also suggest potential value of Gather Town as an educational tool under COVID19 pandemic. Therefore, this research will contribute to the application and utilization of Gather Town in the field of education.

• Journal of The Korean Association of Information Education
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• v.26 no.4
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• pp.229-238
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• 2022

At the time of discussing the 2022 revised curriculum, the demand for normalization of information education is increasing. This study was conducted on the case of the information curriculum for the upper elementary grades responding to such needs. For 14 6th grade students of Elementary School B in K Metropolitan City, 4 core areas of the information curriculum, including computing system, data, algorithm & programming, and digital culture, were covered through classes. Cooperative classes were conducted between students by using the cloud-based application according to the class. In addition, it was intended to supplement the curriculum by suggesting ideas for artificial intelligence education area, and to improve the density of research with additional investigation on foreign information education cases. However, the need for independent organization of the information curriculum was strongly confirmed in that the current curriculum for information classes lacked sufficient school hours and had to be operated in combination with other subjects in the form of a project for this case study. It is hoped that this study will serve as a small foundation for the establishment of the information curriculum for the upper elementary grades in the future.