• Steel and Composite Structures
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• 제43권2호
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• pp.257-270
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• 2022

Recycled aggregate concrete (RAC) is rarely used in load-carrying structural members. To widen its structural application, the compressive behavior of a promising type of composite column, steel-fiber reinforced polymer (FRP) double-tube confined RAC column, has been experimentally and analytically investigated in this study. The objectives are the different performance of such columns from their counterparts using natural aggregate concrete (NAC) and the different mechanisms of the double-tube and single-tube confined concrete. The single-tube confined concrete refers to that in concrete-filled steel tubular (CFST) columns and concrete-filled FRP tubular (CFFT) columns. The test results showed that the use of recycled coarse aggregates (RCA) affected the axial load-strain response in terms of deformation capacity but such effect could be eliminated with the increasing confinement. The composite effect can be triggered by the double confinement of the steel and carbon FRP (CFRP) tubes but not by the steel and polyethylene terephthalate (PET) FRP tubes. The proposed analysis-oriented stress-strain model is capable to capture the load-deformation history of such steel-FRP double-tube confined concrete columns under axial compression.

• The Journal of Asian Finance, Economics and Business
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• 제9권9호
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• pp.105-114
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• 2022

Financial markets have long been known to be prone to behavioral biases. One such behavioural bias that is consequential yet pervasive in financial markets is the herd effect. The objective of this study is to determine whether or not there exist herd behaviour in the new and bourgeoning Decentralized Finance (DeFi) Tokens market. This is accomplished by using daily returns of 22 DeFi tokens from January 29, 2017 to August 19, 2021, and the Cross-sectional Absolute Deviation (CSAD) of market returns to capture herd behavior. The results fail to provide any evidence of herding in the DeFi token market on bullish days, that is days for which the average market returns is positive. For bearish days however, that is days for which the market returns is negative, our empirical findings point to the presence of adverse herding in the DeFi token market. This phenomenon can be explained to some extent by the investor composition of the DeFi market. The DeFi token space is a growth market dominated by experts and/or enthusiasts who are insulated against the temptation and panic of negative market swings by the level of market and technical information they possess on the assets they invest.

• 멤브레인
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• 제33권2호
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• pp.53-60
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• 2023

기계적 에너지는 생물학 및 환경 시스템에서 트라이보 전기 나노제너레이터(TENG)로 얻을 수 있다. 웨어러블 전자제품에서 TENG는 진동 센서에 적용된 인간의 움직임에서 생체역학적 에너지를 수확할 수 있다는 점에서 많은 의미를 지닌다. 웨어러블 TENG은 습기에 취약하며, 폴리테트라플루오로에틸렌(PTFE)은 이러한 용도에 사용되는 우수한 소수성 물질이다. 높은 전기 음성 불소 원자의 존재는 매우 낮은 표면 에너지로 이어진다. 동시에 미세다공막 표면에 전자를 효율적으로 포획함으로써 소자의 성능이 증가한다. PTFE에 비해 상대적으로 적은 플루오라이드 원자의 존재로 인해 폴리비닐리덴 플루오라이드(PVDF)에서도 유사한 거동을 보인다.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3472-3484
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• 2023

The objective of this research is to assess the seismic performance of different types of electrical cabinets in nuclear power plants. The cabinets under investigation are: (a) Case 1: a short single cabinet; (b) Case 2: a tall single cabinet; (c) Case 3: separated cabinets; and (d) Case 4: a combined cabinet with coupling effects. To accurately capture the real behavior of the cabinet, three-dimensional finite element models are developed using ANSYS with connection non-linearity. Frequency domain decomposition (FDD) is used to determine the dynamic properties of the cabinets from shaking table testing data, and these results are utilized to validate the numerical model. The close match between the experimental and numerical results obtained from the modal analysis demonstrates the accuracy of the numerical model. Subsequently, transient structural analysis is performed on the validated models to explore seismic performance. The results show that the acceleration response of the combined cabinet is lower than the single cabinet and the separated cabinet. This observation suggests that top anchors used to combine two different types of cabinets play a crucial role in assessing the efficiency and seismic resistance of electrical cabinets in a nuclear power plant.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.209-214
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• 2023

The effect of thermal annealing on defect recovery of in-core neutron-irradiated 4H-SiC was investigated. Au/SiC Schottky diodes were manufactured using a 4H-SiC epitaxial wafer that was neutron-irradiated at the HANARO research reactor. The electrical characteristics of their epitaxial layers were analyzed under various conditions, including different neutron fluences (1.3 × 10¹⁷ and 2.7 × 10¹⁷ neutrons/cm²) and annealing times (up to 2 h at 1700 ℃). Capacity-voltage measurements showed high carrier compensation in the neutron-irradiated samples and a recovery tendency that increased with annealing time. The carrier density could be recovered up to 77% of the bare sample. Deep-level-transient spectroscopy revealed intrinsic defects of 4H-SiC with energy levels 0.47 and 0.68 eV below the conduction-band edge, which were significantly increased by in-core neutron irradiation. A previously unknown defect with a high electron-capture cross-section was discovered at 0.36 eV below the conduction-band edge. All defect concentrations decreased with 1700 ℃ annealing; the decrease was faster when the defect level was shallow.

• 대한토목학회논문집
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• 제26권4A호
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• pp.577-585
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• 2006

본 연구에서는 비선형 전단변형을 고려할 수 있는 Timoshenko보 이론을 정식화 하였다. 제안된 모델은 전단변형을 고려하므로서 짧은 기둥이나 전단 지배 기둥에서 일반적인 Bernoulli보 이론 보다 합리적인 결과를 보여준다. 단면은 층상화 모델을 이용하였으며, 층상화 단면 모델은 단면을 분활하여 소성화 진행과정을 관찰할 수 있으며 축력과 모멘트의 상호작용을 알 수 있다. 정식화한 요소는 일반적인 철근 콘크리트 부재의 해석을 위해 유한요소 프로그램에 적용하였다. 철근콘크리트 기둥의 해석을 실험결과와 비교하였고, 철근콘크리트 기둥에 대한 거동특성을 분석하였다.

• International Journal of Internet, Broadcasting and Communication
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• 제15권4호
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• pp.9-20
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• 2023

In the aftermath of the COVID-19 pandemic, the importance of collective efforts in promoting health preventive behaviors is accentuated, bringing sociopolitical factors into focus. To fully capture psychological drivers of health preventive behaviors in risk situations, anchored on the Model of Risk Information Seeking and Processing (RISP; Griffin, Dunwoody, and Neuwirth 1999), in retrospect of the recent COVID-19 pandemic, we explored whether and how individuals' vaccination behaviors are predicted by RISP-related variables (information insufficiency, affective responses, perceived information gathering capacity, subjective norms) and one's political identity. Findings from a survey of 705 adult participants in the U.S. showed that the effects of one's risk information insufficiency on his or her information seeking and affective response regarding the pandemic, which is also related to their risk susceptibility perceptions. More importantly, the impact of political identity on one's perceived risk susceptibility, and its association with vaccination behaviors are also identified. The findings of this study provide valuable insights for the development of effective health communication strategies for preventive health behaviors.

• Asia pacific journal of information systems
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• 제33권3호
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• pp.737-767
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• 2023

With the availability of big customer data and advances in machine learning techniques, the prediction of customer behavior at the session-level has attracted considerable attention from marketing practitioners and scholars. This study aims to predict customer purchase conversion at the session-level by employing customer profile, transaction, and clickstream data. For this purpose, we develop a multimodal deep learning fusion model with dynamic and static features (i.e., DS-fusion). Specifically, we base page views within focal visist and recency, frequency, monetary value, and clumpiness (RFMC) for dynamic and static features, respectively, to comprehensively capture customer characteristics for buying behaviors. Our model with deep learning architectures combines these features for conversion prediction. We validate the proposed model using real-world e-commerce data. The experimental results reveal that our model outperforms unimodal classifiers with each feature and the classical machine learning models with dynamic and static features, including random forest and logistic regression. In this regard, this study sheds light on the promise of the machine learning approach with the complementary method for different modalities in predicting customer behaviors.

• Advances in nano research
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• 제16권3호
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• pp.251-263
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• 2024

This article investigates the free vibration behavior of carbon nanotube reinforced composite (CNTRC) beams embedded using variational analytical methods and artificial neural networks (ANN). The material properties of layered functionally graded CNTRC (FG-CNTRC) beams are estimated using nonlocal parameters modified power-law with different types of CNT distributions through the thickness direction of the beam. Adopting Eringen's nonlocal elasticity theory to capture the small size effects, the nonlocal governing equations are derived and solved using the analytical method. And also, the problem was analyzed using the ANN method. The architecture of the proposed ANN model is 3-9-1. In the experiments, we used 112 different data to predict the natural frequency using ANN. Based on the nonlocal differential constitutive relations of Eringen, the equations of motion as well as the boundary conditions of the beam are derived using Hamilton's principle. The classical beam theory is used to formulate a governing equation for predicting the free vibration of laminated CNTRC beams. According to the experimental results, the prediction ability of the ANN model is very good and the natural frequency can be predicted in ANN without attempting any experiments.

• 디자인학연구
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• 제20권3호
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• pp.29-38
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• 2007

이동통신 시장을 둘러싼 기업들 간의 경쟁은 갈수록 치열해 지는 양상을 보인다. 이러한 상황 속에서 지속적인 이동 통신 산업의 성장을 이끌어내고 아시아 시장에서의 앞선 경쟁력을 유지하기 위해서는 첨단 기술개발은 물론, 각 나라 시장의 특성에 대한 이해가 필요하다. 국가의 각각 다른 지역적 이해를 바탕으로 한 차별화된 마케팅 전략을 통해 효과적으로 현지 시장에 접근하려는 노력이 요구되는 상황이다. 이를 위해서는 각국 사용자의 이용 행태 및 성향의 차이를 밝혀 향 후 디자인 방향을 제시하는 것이 본 연구의 목적이다. 본 연구의 방법으로 한/중/일 삼국을 중심으로 온라인 서베이가 이루어졌다. 연구 조사 내용은 1) 모바일폰의 이용자 행태 2) 모바일폰 디자인 및 UI 4) 모바일폰 기능과 서비스에 대한 인식 5) 제조사에 관한 인식이다. 본 연구 결과 각국별 공통점 차이점을 발견할 수 있었다. 1) 첫째 국의 모바일폰 관련 인식 및 문화는 기술적 성숙도, 통신사/제조사의 정책 및 전략, 국민적 성향이 어우러져 형성되는 것으로 밝혀졌다. 2) 둘째 기술적 성숙도와 관련된 항목에 있어서는 한국과 일본이 유사한 성향을 보이는 반면, 국민적 성향과 관련된 항목에서는 한국과 중국이 유사한 성향을 나타내는 것으로 보인다. 3) 셋째 통신사/제조사의 정책 및 전략과 관련된 항목은 한중일 각 사가 서로 다른 특성을 나타내고 있었다. 각국의 공통점 및 차이점에 관한 결과는 각 나라를 이해하는데 좋은 자료가 될 뿐 아니라 본국에서 타국으로 진출 시 좋은 기초 자료가 되리라 본다. 또한 단순 비교에 그치지 않고 본 연구결과를 근거로 하여 신기술에 관한 디자인개발 전략에 적용한다면 더 큰 의의가 있겠다.