• Smart Structures and Systems
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• 제24권3호
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• pp.333-343
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• 2019

The possibility of adopting vibration-powered wireless nodes has been largely investigated in the last years. Among the available technologies based on the piezoelectric effect, the most common ones consist of a vibrating beam covered by electroactive layers. Another energy harvesting strategy is based on the use of piezoelectric strips attached to a hosting structure subjected to dynamic loads. The hosting structure, for example, can be the system to be equipped with wireless nodes. Such strategy has received few attentions so far and no analytical studies have been presented yet. Hence, the original contribution of the present paper is concerned with the development of analytical solutions for the electrodynamic analysis and design of piezoelectric polymeric strips attached to relatively large linear elastic structural systems subjected to random vibrations at the base. Specifically, it is assumed that the dynamics of the hosting structure is dominated by the fundamental vibration mode only, and thus it is reduced to a linear elastic single-degree-of-freedom system. On the other hand, the random excitation at the base of the hosting structure is simulated by filtering a white Gaussian noise through a linear second-order filter. The electromechanical force exerted by the polymeric strip is negligible compared with other forces generated by the large hosting structure to which it is attached. By assuming a simplified electrical interface, useful new exact analytical expressions are derived to assess the generated electric power and the integrity of the harvester as well as to facilitate its optimum design.

• Safety and Health at Work
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• 제10권3호
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• pp.321-326
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• 2019

Background: Performing cognitive tasks and muscular fatigue have been shown to increase muscle activity of the lower extremity during quiet standing. A common intervention to reduce muscular fatigue is to provide a softer shoe-surface interface. However, little is known regarding how muscle activity is affected by softer shoe-surface interfaces during static standing. The purpose of this study was to assess lower extremity muscular activity during erect standing on three different standing surfaces, before and after an acute workload and during cognitive tasks. Methods: Surface electromyography was collected on ankle dorsiflexors and plantarflexors, and knee flexors and extensors of fifteen male participants. Dependent electromyography variables of mean, peak, root mean square, and cocontraction index were calculated and analyzed with a $2{\times}2{\times}3$ within-subject repeated measures analysis of variance. Results: Pre-workload muscle activity did not differ between surfaces and cognitive task conditions. However, greater muscle activity during post-workload balance assessment was found, specifically during the cognitive task. Cognitive task errors did not differ between surface and workload. Conclusions: The cognitive task after workload increased lower extremity muscular activity compared to quite standing, irrespective of the surface condition, suggesting an increased demand was placed on the postural control system as the result of both fatigue and cognitive task.

• 한국BIM학회 논문집
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• 제8권4호
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• pp.49-59
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• 2018

Recently, the application of BIM for port & harbour facilities has been increasing, as it is widely applied to the infrastructure field both at domestic and abroad. However, the port and harbour projects still have very poor facilities information management system and the application level of BIM is very low compared to other facilities. Even if BIM is applied for those project, it is very difficult to determine in advance what information is needed without an accurate understanding of the business process. The purpose of this study is to develop a BIM framework for port & harbour facilities and to examine its applicability. To do this, we structured the classification of the port & harbour facilities and constructed object-based classification system based on ISO12006-3 standard. We also derived the BIM framework requirements from the viewpoint of process, standard, interface, and information, and confirmed the linkage of the BIM object classification system in the framework item. The applicability of the BIM framework for inspection process cases of port & harbour was examined. Accordingly, this study can solve requirement setting method, which is the non - procedural and non - systematic project information, in the BIM application process of the port & harbour project with the BIM framework. In addition, the framework is expected to be integrated into the system to play a key role in the selection of project objectives, and the ability to clearly identify the information requirements required by the BIM manager to perform the project.

• 한국정보통신학회논문지
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• 제23권5호
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• pp.547-554
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• 2019

2015년 교육과정 개편으로 중학교 정보교과가 필수로 지정됨에 따라 초중고등학교는 물론 대학에서도 프로그래밍 교육을 강화하고 있다. 아두이노는 프로그래밍 교육을 위해 사용되는 대표적인 도구 중 하나로 그 유용성은 다양한 사례 연구를 통해 입증되었다. 하지만 기존 아두이노 기반 키트는 연결 방법이 복잡하거나, 확장성이 떨어지는 등 하드웨어 의존적인 단점을 가지고 있다. 이러한 문제점을 보완하기 위한 방안으로 모듈 기반의 구조를 가지고, 동일한 인터페이스를 통해 기능 확장이 가능하며, 다양한 수준에서 학습에 사용할 수 있는 아두이도 호환 키트 설계를 제안하였다. 이 논문에서는 제안한 키트의 요구 조건을 만족시키는 FRUTO 키트와 이를 사용하기 위한 소프트웨어 구현 방법을 설명한다. FRUTO 키트는 몇 번의 디자인 변경을 통해 현재의 형태로 결정되었으며, 현재 출시 전 테스트 진행을 준비 중에 있다.

• 마이크로전자및패키징학회지
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• 제29권1호
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• pp.35-41
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• 2022

5G 시대를 맞아, 인공지능, 클라우드 컴퓨팅, 자율주행 차량, 스마트 제조 등의 기술 소요가 증가하고 있다. 전자기기의 고효율을 위해 고집적회로 및 패키징 연구는 중요하다. 전해도금된 솔더는 범프 조성의 균일성에 한계가 있다. 작은 크기의 솔더 파우더로 구성된 솔더 페이스트는 고집적 패키징에 일반적으로 사용되는 솔더 중 하나이다. 솔더 페이스트에 나노 입자를 첨가하거나 기판 표면 마감 처리를 하여 젖음성을 향상시키고, 금속 패드 계면에서 금속간화합물의 성장을 억제하는 연구가 진행중이다. 본 논문은 나노 입자 첨가를 통한 솔더 페이스트의 젖음성 향상과 계면 금속간화합물의 성장을 억제하는 원리에 대하여 설명한다.

• 센서학회지
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• 제31권4호
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• pp.249-254
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• 2022

To achieve high-performance colloidal quantum dot light-emitting diodes (QD-LEDs), the use of a densely packed QD film is crucial to prevent the formation of leakage current pathways and increase in interface resistance. Spin coating is the most common method to deposit QDs; however, this method often produces pinholes that can act as short-circuit paths within devices. Since state-of-the-art QD-LEDs typically employ mono- or bi-layer QDs as an emissive layer because of their low conductivities, the use of a densely packed and pinhole-free QD film is essential. Herein, we introduce the Langmuir-Blodgett (LB) technique as a deposition method for the fabricate densely packed QD films in QD-LEDs. The LB technique successfully transfers a highly dense monolayer of QDs onto the substrate, and multilayer deposition is performed by repeating the transfer process. To validate the comparability of the LB technique with the standard QD-LED fabrication process, we fabricate and compare the performance of LB-based QD-LEDs to that of the spin-coating-based device. Owing to the non-destructiveness of the LB technique, the electroluminescence efficiency of the LB-based QD-LEDs is similar to that of the standard spin coating-based device. Thus, the LB technique is promising for use in optoelectronic applications.

• Steel and Composite Structures
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• 제48권6호
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• pp.693-708
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• 2023

Composite beams, two materials joined together, have become more common in structural engineering over the past few decades because they have better mechanical and structural properties. The shear connectors between their layers exhibit some deformability with finite stiffness, resulting in interfacial shear slip, a phenomenon known as partial shear interaction. Such a partial shear interaction contributes significantly to the composite beams. To provide precise predictions of the geometric nonlinear behavior shown by two-layered composite beams with interfacial shear slips, a robust analytical model has been developed that incorporates the influence of significant displacements. The application of a higher-order beam theory to the two material layers results in a third-order adjustment of the longitudinal displacement within each layer along the depth of the beam. Deformable shear connectors are employed at the interface to represent the partial shear interaction by means of a sequence of shear connectors that are evenly distributed throughout the beam's length. The Von-Karman theory of large deflection incorporates geometric nonlinearity into the governing equations, which are then solved analytically using the Navier solution technique. Suggested model exhibits a notable level of agreement with published findings, and numerical outputs derived from finite element (FE) model. Large displacement substantially reduces deflection, interfacial shear slip, and stress values. Geometric nonlinearity has a significant impact on beams with larger span-to-depth ratio and a greater degree of shear connector deformability. Potentially, the analytical model can accurately predict the geometric nonlinear responses of composite beams. The model has a high degree of generality, which might aid in the numerical solution of composite beams with varying configurations and shear criteria.

• Journal of Microbiology and Biotechnology
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• 제33권3호
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• pp.299-309
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• 2023

Glutathione peroxidases (Gpx) are a group of antioxidant enzymes that protect cells or tissues against damage from reactive oxygen species (ROS). The Gpx proteins identified in mammals exhibit high catalytic activity toward glutathione (GSH). In contrast, a variety of non-mammalian Gpx proteins from diverse organisms, including fungi, plants, insects, and rodent parasites, show specificity for thioredoxin (TRX) rather than GSH and are designated as TRX-dependent peroxiredoxins. However, the study of the properties of Gpx in the environmental microbiome or isolated bacteria is limited. In this study, we analyzed the Gpx sequences, identified the characteristics of sequences and structures, and found that the environmental microbiome Gpx proteins should be classified as TRX-dependent, Gpx-like peroxiredoxins. This classification is based on the following three items of evidence: i) the conservation of the peroxidatic Cys residue; ii) the existence and conservation of the resolving Cys residue that forms the disulfide bond with the peroxidatic cysteine; and iii) the absence of dimeric and tetrameric interface domains. The conservation/divergence pattern of all known bacterial Gpx-like proteins in public databases shows that they share common characteristics with that from the environmental microbiome and are also TRX-dependent. Moreover, phylogenetic analysis shows that the bacterial Gpx-like proteins exhibit a star-like radiating phylogenetic structure forming a highly diverse genetic pool of TRX-dependent, Gpx-like peroxidases.

• Restorative Dentistry and Endodontics
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• 제49권2호
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• pp.18.1-18.13
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• 2024

Objectives: This study was conducted to evaluate the mechanical properties of relined and non-relined fiberglass posts when cemented to root canal dentin using a conventional dual-cure resin cement or a self-adhesive resin cement. Materials and Methods: Two types of resin cements were utilized: conventional and self-adhesive. Additionally, 2 cementation protocols were employed, involving relined and non-relined fiberglass posts. In total, 72 bovine incisors were cemented and subjected to push-out bond strength testing (n = 10) followed by failure mode analysis. The cross-sectional microhardness (n = 5) was assessed along the root canal, and interface analyses (n = 3) were conducted using scanning electron microscopy (SEM). Data from the push-out bond strength and cross-sectional microhardness tests were analyzed via 3-way analysis of variance and the Bonferroni post-hoc test (α= 0.05). Results: For non-relined fiberglass posts, conventional resin cement exhibited higher pushout bond strength than self-adhesive cement. Relined fiberglass posts yielded comparable results between the resin cements. Type II failure was the most common failure mode for both resin cements, regardless of cementation protocol. The use of relined fiberglass posts improved the cross-sectional microhardness values for both cements. SEM images revealed voids and bubbles in the incisors with non-relined fiberglass posts. Conclusions: Mechanical properties were impacted by the cementation protocol. Relined fiberglass posts presented the highest push-out bond strength and cross-sectional microhardness values, regardless of the resin cement used (conventional dual-cure or self-adhesive). Conversely, for non-relined fiberglass posts, the conventional dual-cure resin cement yielded superior results to the self-adhesive resin cement.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제2권12호
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• pp.855-864
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• 2013

판단 트리 분류는 데이터 마이닝의 중요한 문제의 하나이고, 데이터 마이닝은 대형 데이터베이스 기술의 중요한 과제가 되고 있다. 그러므로 데이터베이스와 데이터 마이닝 시스템의 결합 노력은 판단 트리 분류와 같은 데이터 마이닝 기능을 지원하는 데이터베이스 기초 기능의 개발로 이어지고 있다. 이런 기초 기능은 분류 알고리즘의 SQL 구현을 지원하는 특수한 데이터베이스 연산들로 구현되며, 특정 알고리즘을 구현하여 데이터베이스 시스템의 구성 모듈로 사용하고 있다. 데이터마이닝 기능을 제공하는 데이터베이스 기초 기능의 개발에는 두 가지 관점이 있다. 하나는 데이터 마이닝 기능을 분석해서 그런 기능들을 제공하는 데이터베이스 공통 기초 기능을 확인하는 것, 다른 하나는 데이터베이스 시스템의 인터페이스의 한 부분으로 이런 기초 기능의 구현을 위한 확장된 메커니즘을 제공하는 것이다. 데이터마이닝에서 어떤 기초 기능들을 DBMS에 저장할 것인가는 어려운 문제 중에 하나이다. 따라서 본 논문에서는 이러한 문제를 해결하기 위하여, 최적화된 판단 트리 분류기를 만들고 데이터베이스 기초 기능에 대해서 기술한다. 판단 트리 분류 알고리즘의 유용한 연산들을 확인하고, 상업적 DBMS에서 이러한 기초 기능의 구현에 대해서 기술하고, 성능 비교를 위한 실험 결과를 제시한다.