• Structural Engineering and Mechanics
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• 제24권1호
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• pp.1-18
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• 2006

Strengthening of existing old structures has traditionally been accomplished by using conventional materials and techniques, viz., externally bonded steel plates, steel or concrete jackets, etc. Alternatively, fibre reinforced polymer composite (FRPC) products started being used to overcome problems associated with conventional materials in the mid 1950s because of their favourable engineering properties. Effectiveness of FRPC materials has been demonstrated through extensive experimental research throughout the world in the last two decades. However there is a need to use refined analytical tools to simulate response of strengthened system. In this paper, an attempt has been made to develop a numerical model of strengthened reinforced concrete (RC) beams with FRPC laminates. Material models for RC beams strengthened with FRPC laminates are described and verified through a nonlinear finite element (FE) commercial code, with the help of available experimental data. Three dimensional (3D) FE analysis has been performed by assuming perfect bonding between concrete and FRPC laminate. A parametric study has also been performed to examine effects of various parameters like fibre type, stirrup's spacing, etc. on the strengthening system. Through numerical simulation, it has been shown that it is possible to predict accurately the flexural response of RC beams strengthened with FRPC laminates by selecting an appropriate material constitutive model. Comparisons are made between the available experimental results in literature and FE analysis results obtained by the present investigators using load-deflection and load-strain plots as well as ultimate load of the strengthened beams. Furthermore, evaluation of crack patterns from FE analysis and experimental failure modes are discussed at the end.

• Genomics & Informatics
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• 제12권4호
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• pp.283-288
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• 2014

Among all serious diseases globally, diabetes (type 1 and type 2) still poses a major challenge to the world population. Several target proteins have been identified, and the etiology causing diabetes has been reasonably well studied. But, there is still a gap in deciding on the choice of a drug, especially when the target is mutated. Mutations in the KCNJ11 gene, encoding the kir6.2 channel, are reported to be associated with congenital hyperinsulinism, having a major impact in causing type 1 diabetes, and due to the lack of its 3D structure, an attempt has been made to predict the structure of kir6.2, applying fold recognition methods. The current work is intended to investigate the affinity of four phytochemicals namely, curcumin (Curcuma longa), genistein (Genista tinctoria), piperine (Piper nigrum), and pterostilbene (Vitis vinifera) in a normal as well as in a mutant kir6.2 model by adopting a molecular docking methodology. The phytochemicals were docked in both wild and mutated kir6.2 models in two rounds: blind docking followed by ATP-binding pocket-specific docking. From the binding pockets, the common interacting amino acid residues participating strongly within the binding pocket were identified and compared. From the study, we conclude that these phytochemicals have strong affinity in both the normal and mutant kir6.2 model. This work would be helpful for further study of the phytochemicals above for the treatment of type 1 diabetes by targeting the kir6.2 channel.

• Wind and Structures
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• 제29권4호
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• pp.247-270
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• 2019

Wind-resistant design of existing cooling tower structures overlooks the impacts of rainfall. However, rainstorm will influence aerodynamic force on the tower surface directly. Under this circumstance, the structural response of the super-large cooling tower (SLCT) will become more complicated, and then the stability and safety of SLCT will receive significant impact. In this paper, surrounding wind fields of the world highest (210 m) cooling tower in Northwest China underthree typical wind velocities were simulated based on the wind-rain two-way coupling algorithm. Next, wind-rain coupling synchronous iteration calculations were conducted under 9 different wind speed-rainfall intensity combinations by adding the discrete phase model (DPM). On this basis, the influencing laws of different wind speed-rainfall intensity combinations on wind-driving rain, adhesive force of rain drops and rain pressure coefficients were discussed. The acting mechanisms of speed line, turbulence energy strength as well as running speed and trajectory of rain drops on structural surface in the wind-rain coupling field were disclosed. Moreover, the fitting formula of wind-rain coupling equivalent pressure coefficient of the cooling tower was proposed. A systematic contrast analysis on its 3D distribution pattern was carried out. Finally, coupling model of SLCT under different working conditions was constructed by combining the finite element method. Structural response, buckling stability and local stability of SLCT under different wind velocities and wind speed-rainfall intensity combinations were compared and analyzed. Major research conclusions can provide references to determine loads of similar SLCT accurately under extremely complicated working conditions.

• Smart Structures and Systems
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• 제29권1호
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• pp.237-250
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• 2022

Structural health monitoring (SHM) plays an important role in ensuring the safety and functionality of critical civil infrastructure. In recent years, numerous researchers have conducted studies to develop computer vision and machine learning techniques for SHM purposes, offering the potential to reduce the laborious nature and improve the effectiveness of field inspections. However, high-quality vision data from various types of damaged structures is relatively difficult to obtain, because of the rare occurrence of damaged structures. The lack of data is particularly acute for fatigue crack in steel bridge girder. As a result, the lack of data for training purposes is one of the main issues that hinders wider application of these powerful techniques for SHM. To address this problem, the use of synthetic data is proposed in this article to augment real-world datasets used for training neural networks that can identify fatigue cracks in steel structures. First, random textures representing the surface of steel structures with fatigue cracks are created and mapped onto a 3D graphics model. Subsequently, this model is used to generate synthetic images for various lighting conditions and camera angles. A fully convolutional network is then trained for two cases: (1) using only real-word data, and (2) using both synthetic and real-word data. By employing synthetic data augmentation in the training process, the crack identification performance of the neural network for the test dataset is seen to improve from 35% to 40% and 49% to 62% for intersection over union (IoU) and precision, respectively, demonstrating the efficacy of the proposed approach.

• 정보처리학회논문지D
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• 제14D권3호
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• pp.319-328
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• 2007

웹 서비스의 활용 범위가 커지고 실제적인 구현사례가 늘어감에 따라, 웹 서비스 품질모델을 현실적으로 적용할 수 있는 방법에 대한 중요성이 커지고 있다. 웹 서비스 품질을 일관성있게 유지하기 위해서는 웹 서비스 품질보증에 대한 방안이 연구되어야만 한다. 웹 서비스 보증이란 웹 서비스의 품질수준을 일정수준이상으로 유지하기 위한 행위들의 총체를 의미하며, 이를 위해 웹 서비스 품질보증자란 새로운 개념의 관계자가 국제기구에서 웹 서비스 표준으로 새롭게 제시되었다. 웹 서비스 품질보증자는 웹 서비스 사용자들의 품질요구사항을 수렴하여, 웹 서비스 제공자가 일정 품질수준이상의 웹 서비스를 제공할 수 있도록 감시한다. 웹 서비스 제공자와 사용자 그리고, 품질보증자는 웹 서비스 수준을 관리하기 위해 서비스 수준을 측정하여 그 결과에 따라 페널티와 인센티브를 부여하는 SLA(Service Level Agreement) 방식을 적용할 수 있다. 하지만, SLA에서는 서비스 사용자와 제공자가 같은 서비스 항목에 대해 일대일로 대응한다는 전제를 가지고 있어서, 다수사용자와 공공성, 그리고 제3자 관리와 같은 웹 서비스 프레임워크에는 적합하지 않은 점들이 존재한다. 따라서, 웹 서비스에 SLA를 적용하기 위해서는 웹 서비스의 이러한 특성들을 반영한 새로운 보증기법이 필요하다. 본 논문에서는 품질 기대수준을 표현하기 위해 웹 서비스 품질 위탁보증수준이라는 새로운 개념을 제시하고자 한다. 이는 각 사용자의 각 품질항목별 품질기대수준의 최대치라 할 수 있으며, 웹 서비스 품질관계자에게 일관성있는 품질 뷰를 제공한다. 본 논문에서는 이를 이용해 각 품질관계자가 보다 쉽게 일정 수준이상의 품질수준을 유지할 수 있는 방안에 대해 제시하고자 한다.

• 대한토목학회논문집
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• 제32권5D호
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• pp.473-481
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• 2012

천연가스는 타 화석연료에 비해 온실가스를 적게 배출하는 청정연료로서 가채연수가 길고 상대적으로 가격 변동이 적어 세계적으로 사용량이 증대되고 있으며, 이에 따라 신규 가스전 개발 및 대규모의 천연가스 플랜트 건설 사업이 세계 각지에서 추진되고 있다. 특히 다양한 플랜트 사업 중 해외 천연가스 파이프라인 사업의 경우 보다 안정적이고 효율적인 천연가스의 수송을 위해 지역 간이나 국가 간에 적용되는 방식으로서 건설 수요가 괄목할만하게 증가하고 있으며 이미 전체 천연가스 교역의 72%를 차지하고 있다. 그러나 우리나라의 경우 해외의 주요 가스전과의 물리적인 거리 및 저장시설에 한정된 수요 발생으로 인해 해외 파이프라인 공종의 참여가 뒤떨어져 있는 것이 현실이다. 따라서 본 연구에서는 해외 천연가스 파이프라인 사업의 진출을 위해 사업계획 단계를 중심으로 표준화된 업무 프로세스 모델을 구축하고자 하였다. 국 내외의 파이프라인 사업 및 해외건설 프로세스를 분석하고, 해외 천연가스 파이프라인 사업의 특성을 반영하여 3단계의 레벨을 가진 업무 프로세스 모델을 도출하였다. 이후 전문가를 활용하여, 업무 프로세스 모델을 테스트베드에 적용하여 실무적 검증을 수행하였으며, 이와 별도로 추가적인 설문조사를 통해 본 연구에서 제시된 업무 프로세스 모델의 적용성과 효용성을 확인하였다. 본 연구에서 제시된 업무 프로세스 모델을 기반으로 기업의 노하우를 반영한다면, 해외 천연가스 사업 의사결정을 위한 객관적인 기준으로 활용할 수 있을 것으로 기대된다.

• 대한간호학회지
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• 제50권3호
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• pp.487-500
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• 2020

Purpose: This study aimed to evaluate the validity and reliability of the Korean version of Menopause-Specific Quality of Life (MENQOL). Methods: The MENQOL was translated into Korean according to algorithm of linguistic validation process. A total of 308 menopausal women were recruited and assessed using the Korean version of MENQOL (MENQOL-K), the World Health Organization Quality of Life Brief Version (WHOQOL-BREF), and Center for Epidemiological Studies Depression Scale (CES-D-K). In estimating reliability, internal consistency reliability coefficients were calculated. Validity was evaluated through criterion validity and construct validity with confirmatory factor analyses using SPSS 23.0 and AMOS 25.0 software. Results: In item analyses, the "increased facial hair" symptom was excluded because of the low contribution of MENQOL-K. The confirmatory factor analysis supported good fit and reliable scores for MENQOL-K model, and the four-factor structure was validated (χ²=553.28, p<.001, NC=1.84, RMSEA=.05, AGIF=.85, AIC=765.28). The MENQOL-K consists of 28 items in 4 domains, including vasomotor (3 items), psychosocial (7 items), physical (15 items), and sexual subscales (3 items). There was an acceptable criterion validity with moderately significant correlation between MENQOL-K and WHOQOL-BREF. The Cronbach's α for the 4 subsacles ranged from .80 to .93. Conclusion: The MENQOL-K is a valid and reliable scale to measure condition-specific quality of life for perimenopausal and postmenopausal women. It can be used to assess the impact of menopausal symptoms on the quality of life of Korean women in clinical trials.

• International Journal of Internet, Broadcasting and Communication
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• 제9권3호
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• pp.1-8
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• 2017

Recently, the development of the head mounted display (HMD) device has attracted a great deal of attention to the actual contents. Especially, Augmented Reality (AR), which is a mixture of actual information and virtual world information, is focused on. AR HMD is able to interact by arranging virtual objects in real space through spatial recognition using depth camera. In order to naturally mix virtual space with real space, it is necessary to develop a technology for realizing spatial mapping information with high accuracy. The purpose of this paper is to evaluate the optimal configuration of augmented reality application program by realizing accurate spatial mapping information when mapping a real space and an object placement environment using HoloLens. To do this, we changed the spatial mapping information in real space to three levels, which are the number of meshes used in cubic meters to scan step by step. After that, it was compared with the 3D model obtained by changing the actual space and mesh number. Experimental result shows that the higher the number of meshes used in cubic meters, the higher the accuracy between real space and spatial mapping. This paper is expected to be applied to augmented reality application programs that require scanning of highly mapped spatial mapping information.

• Earthquakes and Structures
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• 제9권3호
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• pp.603-623
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• 2015

The scale and nature of the recent earthquakes in the world and the related earthquake disaster index coerce the concerned community to become anxious about it. Therefore, it is crucial that seismic lateral load effect will be appropriately considered in structural design. Application of seismic isolation system stands as a consistent alternative against this hazard. The objective of the study is to evaluate the structural and economic feasibility of reinforced concrete (RC) buildings with base isolation located in medium risk seismic region. Linear and nonlinear dynamic analyses as well as linear static analysis under site-specific bi-directional seismic excitation have been carried out for both fixed based (FB) and base isolated (BI) buildings in the present study. The superstructure and base of buildings are modeled in a 3D finite element model by consistent mass approach having six degrees of freedom at each node. The floor slabs are simulated as rigid diaphragms. Lead rubber bearing (LRB) and High damping rubber bearing (HDRB) are used as isolation device. Change of structural behaviors and savings in construction costing are evaluated. The study shows that for low to medium rise buildings, isolators can reduce muscular amount of base shears, base moments and floor accelerations for building at soft to medium stiff soil. Allowable higher horizontal displacement induces structural flexibility. Though incorporating isolator increases the outlay, overall structural cost may be reduced. The application of base isolation system confirms a potential to be used as a viable solution in economic building design.

• 전기학회논문지
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• 제63권1호
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• pp.99-107
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• 2014

In this paper, a landmark based localization system using a Kinect sensor is proposed and evaluated with the implemented system for precise and autonomous navigation of low cost robots. The proposed localization method finds the positions of landmark on the image plane and the depth value using color and depth images. The coordinates transforms are defined using the depth value. Using coordinate transformation, the position in the image plane is transformed to the position in the body frame. The ranges between the landmarks and the Kinect sensor are the norm of the landmark positions in body frame. The Kinect sensor position is computed using the tri-lateral whose inputs are the ranges and the known landmark positions. In addition, a new matching method using the pin hole model is proposed to reduce the mismatch between depth and color images. Furthermore, a height error compensation method using the relationship between the body frame and real world coordinates is proposed to reduce the effect of wrong leveling. The error analysis are also given to find out the effect of focal length, principal point and depth value to the range. The experiments using 2D bar code with the implemented system show that the position with less than 3cm error is obtained in enclosed space($3,500mm{\times}3,000mm{\times}2,500mm$).