Daegu Gyeongbuk Institute of Science and Technology
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Analysis on the Power Handling Capability of Ground Navigation Loran-C Transmitting Antenna
No full text본 논문에서는 지상항법용 로란-C 송신 안테나의 전력 처리 용량을 분석하였다. 지상항법용 단축형 우산형 모노폴 안테나의 전력 처리 용량은 안테나 실효고 이외에 안테나에 사용된 기부 및 지선 애자의 절연 전압에 의해 결정된다. 본 논문에서는 송신 안테나 전력에 따른 기부 애자의 절연 전압과 안테나와 지선이 연결되는 지점의 절연 전압을 구하기 위해 안테나 높이에 대한 안테나 전압을 도출하여 사용된 애자들의 절연 전압과 비교하여 안테나의 전력 처리 용량을 분석할 수 있도록 하였다. 송신국 안테나를 대상으로 사용된 애자의 절연 특성과 비교 분석한 결과, 50[kW]~100[kW] 안테나 출력에 따라 지선 연결점들의 절연 전압은 약 69[kV]~128[kV]로 2개의 지선 애자를 직렬로 사용하는 방법이 적합하며, 안테나 기저부의 절연 전압은 64.8[kV]~91.7[kV]로 안테나 출력을 50[kW]에서 100[kW]로 운용할 수 있는 전력 처리 용량을 가질 수 있었다.
The power handling capacity of the Loran-C transmitting antenna for terrestrial navigation was analyzed in this paper. The power handling capacity of a shortened umbrella-type monopole antenna for terrestrial navigation is determined by the insulation voltages of the base and guy insulators used in the antenna in addition to the effective height of the antenna. In this paper, the insulation voltage of the base insulator according to the transmitting antenna power was derived, and in order to obtain the insulation voltages of the points where the antenna and the guy lines are connected, the antenna voltages for the antenna height were derived. By comparing with the insulation voltages of the insulators used, the power handling capacity of the antenna can be analyzed. As a result of comparative analysis of the insulation characteristics of the insulators used for the transmitter antenna, the guy line insulation voltages were approximately 69[kV]~128[kV] depending on the antenna output of 50[kW]~100[kW], so the method of using two guy insulators in series was appropriate, and the insulation voltages at the base of the antenna were 64.8[kV]~91.7[kV], so it was possible to have a power handling capacity that could operate the antenna output power from 50[kW] to 100[kW].FALSEkc
hMAGEA2 as a potential diagnostic and therapeutic target for melanoma progression and metastasis
Get PDFThe incidence of melanoma, a highly aggressive skin cancer, continues to increase worldwide, particularly among populations with lighter skin tones. The diagnostic challenge of melanoma lies in the absence of a distinctive clinical presentation, as its characteristics vary based on anatomical location, growth type, and histopathology. The melanoma-associated antigen (MAGE) gene family is differentially expressed in various human cancers, including melanoma. In this study, we explored the association between human MAGEA2 (hMAGEA2) expression and melanoma. Using a human melanoma tissue array, we confirmed that hMAGEA2 expression was higher in melanoma and metastatic melanoma than in normal tissues. Additionally, we used SK-MEL-5 and SK-MEL-28 cell lines to investigate the cellular and molecular mechanisms underlying melanoma progression and invasiveness. In SK-MEL-5 and SK-MEL-28 cells, hMAGEA2 overexpression accelerated cell proliferation. Conversely, the knockdown of hMAEGA2 reduced cell proliferation, colony formation, and migration significantly and induced arrest at the G2/M phase of the cell cycle. With respect to the molecular mechanism, the knockdown of hMAGEA2 decreased the phosphorylation of Akt, JNK, and p38 MAPK. Additionally, hMAGEA2 knockdown reduced tumor formation significantly at the in vivo level. Collectively, the robust correlation between hMAGEA2 and melanoma metastasis supports the potential utility of hMAGEA2 as both a diagnostic marker and novel therapeutic target for patients with melanoma metastasis. © 2024 Cellular and Molecular Biology Association. All rights reserved.TRUEsciescopu
THERMAL INFRARED POLARIZATION SENSOR AND MANUFACTURING METHOD THEREOF, THERMAL INFRARED POLARIZATION SENSOR ARRAY INCLUDING THE SAME
No full textFacile Surface Stabilization Strategy for Efficient and Stable Perovskite Quantum Dot Solar Cells
No full textCsPbI3 PQD solids suffer from degradation in optoelectrical properties and film stability because of numerous trap sites on the PQD surface, which are generated after the ligand exchange process. Therefore, additional PQD surface stabilization strategy should be introduced which can improve the film quality of CsPbI3 PQD solids using covalent short-chain triphenylphosphine oxide (TPPO) ligands dissolved in an octane solvent. It is found that the TPPO ligand can bind with trap sites through Lewis-base interaction and the nonpolar solvent octane can preserve the PQD surface. As a result, the CsPbI3 PQD solids stabilized using the TPPO-octane solution showed reduced surface trap density than the control PQD solids. Consequently, CsPbI3 PQD solar cells which were stabilized using TPPO-octane solution provide a boosted power conversion efficiency and operational stability compared to control device
산성 매질에서 산화질소 전기환원을 통한 고 선택적이며 고내구성의 상온 암모니아 생산 전기촉매
No full textAmmonia, nitric oxide electroreduction, nitrogen fixation, nitrogen-doped carbon nanorods, electrocatalysisAbstract i
Table of Contents ii
List of Tables v
List of Figures vii
1. Introduction 1
1.1. Ammonia: Fueling the Future 1
1.2. Global Ammonia Demand Outlook 3
1.3. Beyond Haber-Bosch’s Ammonia 5
1.4. Nitric Oxide Reduction: An Electrochemical Breakthrough 8
1.5. Mechanism of Nitric Oxide Electroreduction 10
1.6. Current Insights and Future Challenges 12
1.7. Objectives of the Thesis 14
2. Experimental Methods 16
2.1. Synthesis of Transition Metal Nanoparticle-Embedded N-Doped Carbon nanorods (TM-NCNR) 16
2.1.1. Chemicals and Materials 16
2.1.2. Synthesis of TM-NCNR and Nomenclature 17
2.1.3. Synthesis of Other Control Samples and Nomenclature 17
2.2. Synthesis of copper nanowires infused porous multi-nano-channel N-doped carbon nanorods (Cu-mNCNR) 18
2.2.1. Chemicals and Materials 18
2.2.2. Synthesis of Cu-mNCNR and Nomenclature 18
2.2.3. Synthesis of control sample (Cu-NCNR) 19
3. Characterization Methods 20
3.1. Physicochemical Characterization 20
3.2. Electrochemical Characterization 21
3.2.1. Electrode Fabrication 21
3.2.2. Electrochemical Cell Setup and Testing 21
3.2.3. Linear sweep voltammetry 22
3.2.4. Chronoamperometry 22
3.2.5. Tafel slope analysis 23
3.2.6. Electrochemical impedance spectroscopy 23
3.2.7. Electrochemical active surface area 23
3.3. The Zn-NO battery assembly and testing 24
3.4. Product Quantification 25
3.4.1. Colorimetric techniques 25
3.4.2. 1H NMR quantification of NH3 28
3.4.3. Gas chromatography quantification of H2 29
3.5. Equations used for the calculations 29
3.5.1. Average yield rate of the product 29
3.5.2. Faradaic efficiency 30
3.5.3. Turn-over frequency 30
4. Results and Discussion 31
4.1. Exploration of Various TM Active Sites with N-doped Carbon Nanorods for Selective Electrosynthesis of NH3 31
4.1.1. Overview 31
4.1.2. Phase formation and analysis 32
4.1.3. Morphological analysis 34
4.1.4. Chemical states analysis 38
4.1.5. Nature of carbon and chemical composition 42
4.1.6. BET surface area and pore size distribution 45
4.1.7. Electrochemical Nitric Oxide Reduction Activity 46
4.1.8. Effect of Graphitization and Porosity 54
4.1.9. Elucidating The Nature of Active Site and Effect of N-Heteroatom Doping .. 62
4.1.10. Robustness of the Ni-NCNR700 and Post-eNORR Study 66
4.1.11. Summary 70
4.2. Development of Copper Nanowires Infused in N-doped Carbon Nanorods for Selective Electrosynthesis of NH3 and Demonstration of Zn-NO Battery 71
4.2.1. Overview 71
4.2.2. Phase evolution and analysis 72
4.2.3. Morphological analysis 74
4.2.4. Raman analysis and chemical composition 79
4.2.5. Surface composition and electronic configurations 80
4.2.6. Electrocatalytic activity of Cu-mNCNR on eNORR 84
4.2.7. Inception of enhanced catalytic activity and N-source identification 92
4.2.8. Robustness of Cu-mNCNR2 and Post-electrolysis Study 97
4.2.9. Zn-NO Battery-A Proof-of-Concept Device 103
4.2.10. Summary 106
5. Conclusion 107
References 109
요 약 문 125MasterdCollectio
Advanced Handheld Micro-Surgical System using an Hall Sensor and a Magnet Trocar for Retinal Microsurgery
No full textDiseases affecting the retina, such as retinal detachment, diabetic retinopathy, and macular degeneration, are significant contributors to blindness globally, with a substantial risk of vision loss among those afflicted. Surgical treatment of these conditions is complex due to the delicate nature of retinal tissue and the challenges posed by involuntary hand movements. While existing methods aim to compensate for hand tremors using sensor-based systems, they are hindered by limitations in accurately tracking retinal surface movement during surgery, particularly in response to patient movements under anesthesia. To address these issues, this study proposes a novel handheld micro-surgical tool equipped with a 1-degree of freedom (DOF) mechanism and a 3-axis Hall sensor to mitigate physiological hand tremors effectively. By utilizing magnetic flux density measurements, the tool can pinpoint the position of a magnet embedded within the surgical instrument, enabling precise tremor compensation without reliance on a global coordinate system. The design incorporates a piezoelectric (PZT) linear actuator and a Hall sensor for compactness and sensitivity. Optimization of the magnet's dimensions through simulation ensures optimal sensor performance. Experimental validation using artificial and ex-vivo porcine eye models demonstrates the tool's effectiveness in reducing hand tremors, suggesting potential enhancements in the safety and accuracy of retinal surgeries. For the desired positions from 4000 μm to 1000 μm, the RMS error of the synthetic eye model and porcine eye decreased from 71.10 μm to 33.27 μm and 71.36 μm to 33.39 μm, respectively. © 2024 IEEE
Graphene-Liquid Crystal Synergy: Advancing Sensor Technologies across Multiple Domains
No full textThis review explores the integration of graphene and liquid crystals to advance sensor technologies across multiple domains, with a focus on recent developments in thermal and infrared sensing, flexible actuators, chemical and biological detection, and environmental monitoring systems. The synergy between graphene’s exceptional electrical, optical, and thermal properties and the dynamic behavior of liquid crystals leads to sensors with significantly enhanced sensitivity, selectivity, and versatility. Notable contributions of this review include highlighting key advancements such as graphene-doped liquid crystal IR detectors, shape-memory polymers for flexible actuators, and composite hydrogels for environmental pollutant detection. Additionally, this review addresses ongoing challenges in scalability and integration, providing insights into current research efforts aimed at overcoming these obstacles. The potential for multi-modal sensing, self-powered devices, and AI integration is discussed, suggesting a transformative impact of these composite sensors on various sectors, including health, environmental monitoring, and technology. This review demonstrates how the fusion of graphene and liquid crystals is pushing the boundaries of sensor technology, offering more sensitive, adaptable, and innovative solutions to global challenges. © 2024 by the authors.TRUEsciescopu
Chemo- and Regioselective Nickel-Catalyzed Reductive 1,4-Alkylarylation of 1,3-Enynes through an L2NiAr Intermediate
No full textThree-component reductive dicarbofunctionalization reactions of 1,3-enynes have been rarely reported because of the intricate control of chemo- and regioselectivity required, coupled with a limited understanding of radical and catalytic species involved. Herein, we report a nickel-catalyzed reductive 1,4-alkylarylation method for 1,3-enynes to yield tri- and tetrasubstituted allenes using readily accessible alkyl and aryl iodides, featuring a simple operational protocol and mild reaction conditions. In our mechanistic studies, the formation of a propargyl/allenyl radical was substantiated by the isolation of a propargyl dimer, the detection of the corresponding TEMPO-radical adduct, and radical probe experiments. Two reduced L2NiAr complexes, expected to act as catalytic intermediates, were generated and characterized by EPR spectroscopy as NiI complexes. The stoichiometric reaction of L2Ni(p-NCC6H4) with 1,3-enyne and alkyl iodide showed conversion into the corresponding propargyl dimer and allene, suggesting that the reaction encompasses the same key mechanistic steps as the catalytic reaction, i.e., activation of alkyl iodide, generation of a propargyl/allenyl radical, and selective coupling of this radical with the aryl component. © 2024 American Chemical Society.FALSEsciescopu
Machine Fault Diagnosis Based on Sound through Active Learning in Industrial Environments with Labeling Constraints
No full text본 연구는 active learning 방법을 활용하여 라벨링 제약이 있는 산업 환경에서도 높은 성능을 보이는 소리 기반 기계 결함 진단 시스템을 제안한다. 제안하는 시스템은 산업 환경 상에서 데이터 라벨링을 최소화하여 비용 효율성을 향상시키면서도 결함 진단에 있어 유의미하게 높은 성능을 보인다. 산업 환경의 특성에 맞게 active learning 의 파라미터를 최적화하는 추후 연구를 진행하여 추가적인 성능 향상을 기대할 수 있다
Magnetically Controlled Intraocular Delivery of Dexamethasone Using Silica-Coated Magnetic Nanoparticles
Get PDFAlthough the number of patients with eye diseases is increasing, efficient drug delivery to the posterior segment of the eyeball remains challenging. The reasons include the unique anatomy of the eyeball, the blood-aqueous barrier, the blood-retina barrier, and drug elimination via the anterior chamber and uveoscleral routes. Solutions to these obstacles for therapeutic delivery to the posterior segment will increase the efficacy, efficiency, and safety of ophthalmic treatment. Micro/nanorobots are promising tools to deliver therapeutics to the retina under the direction of an external magnetic field. Although many groups have evaluated potential uses of micro/nanorobots in retinal treatment, most experiments have been performed under idealized in vitro laboratory conditions and thus do not fully demonstrate the clinical feasibility of this approach. This study examined the use of magnetic nanoparticles (MNPs) to deliver dexamethasone, a drug widely used in retinal disease treatment. The MNPs allowed sustainable drug release and successful magnetic manipulation inside bovine vitreous humor and the vitreous humor of living rabbits. Therefore, controlled drug distribution via magnetic manipulation of MNPs is a promising strategy for targeted drug delivery to the retina.© 2024 The Authors.TRUEsciescopu