• Title/Summary/Keyword: flow information

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Section Model Study on the Aerodynamic Behaviors of the Cable-Stayed Bridges with Two I-Type Girders Considering Structural Damping and Turbulence Intensity (2개의 I형 거더를 가진 사장교의 구조감쇠비 및 난류강도를 고려한 공기역학적 거동에 관한 단면모형실험 연구)

  • Cho, Jae-Young;Kim, Young-Min;Cho, Young-Rae;Lee, Hak-Eun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.6A
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    • pp.1013-1022
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    • 2006
  • Although the cable-stayed bridges with two I-type girders inherently do not have good aerodynamic characteristics, a lot of the bridges with this type girders are constructed in Korea recently because of an economical merit. This paper investigated the aerodynamic characteristics of the cable-stayed bridges with two I-type girders. Section model tests were conducted in order to investigate the aerodynamic behaviors of this section with varying of the angles of attack, turbulence intensity and damping ratios. Two deck section configurations with different torsional stiffness were studied under construction and after completion respectively. Three types of the fairings were investigated to improve the aerodynamic characteristics of the bridges. The result of this study showed that the traditional section model test in uniform flow estimates the aerodynamic behavior rather pessimistically. The wind induced responses of the bridges were severely varied in accordance with the turbulence intensity and the structural damping ratio. The proposed fairing reduced the magnitude of the vortex-shedding vibrations and buffeting responses. It also increased the wind speed at which flutter occurs. It is expected that these investigations would provide a lot of information for the design of the cable stayed bridges with two I-type girders regarding wind resistance.

Development of Pollutant Transport Model Working In GIS-based River Network Incorporating Acoustic Doppler Current Profiler Data (ADCP자료를 활용한 GIS기반의 하천 네트워크에서 오염물질의 이송거동모델 개발)

  • Kim, Dongsu
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.6B
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    • pp.551-560
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    • 2009
  • This paper describes a newly developed pollutant transport model named ARPTM which was designed to simulate the transport and characteristics of pollutant materials after an accidental spill in upstream of river system up to a given position in the downstream. In particular, the ARPTM incorporated ADCP data to compute longitudinal dispersion coefficient and advection velocity which are necessary to apply one-dimensional advection-dispersion equation. ARPTM was built on top of the geographic information system platforms to take advantage of the technology's capabilities to track geo-referenced processes and visualize the simulated results in conjunction with associated geographic layers such as digital maps. The ARPTM computes travel distance, time, and concentration of the pollutant cloud in the given flow path from the river network, after quickly finding path between the spill of the pollutant material and any concerned points in the downstream. ARPTM is closely connected with a recently developed GIS-based Arc River database that stores inputs and outputs of ARPTM. ARPTM thereby assembles measurements, modeling, and cyberinfrastructure components to create a useful cyber-tool for determining and visualizing the dynamics of the clouds of pollutants while dispersing in space and time. ARPTM is expected to be potentially used for building warning system for the transport of pollutant materials in a large basin.

Method for Flood Runoff Analysis of Main Channel Connected with Interior Floodplain : I. Application for Analysis of Inundation Area in Interior Floodplain (제내지와 하도를 연계한 하천유역의 홍수유출해석: I. 제내지 침수해석에의 적용)

  • Jang, Su Hyung;Yoon, Jae Young;Yoon, Yong Nam;Kim, Won Seok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1B
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    • pp.79-88
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    • 2006
  • In this study, a methodology is developed for flood runoff analysis considering the interaction between interior floodplain and channel. Riparian lowland is modeled as storage areas by HEC-RAS and is connected with main channel through gravity drainage structure and pumping stations. As a result, we were able to compute the difference between runoff into the interior floodplain and delayed runoff to main channel from interior floodplain. This allowed us to compute the storage change in the interior floodplain and corresponding inundation areas. Furthermore, the levee is modeled as a lateral structure and the flood from the main channel to interior floodplain is modeled by installing a weir on top of it. In addition, levee breach is also modeled so that flooding from main channel to interior floodplain can be considered. Computed flooding depth in the storage areas are compared with elevation to identify the inundated areas and flood maps can then be produced for a desired time or for the extent of flooding given a flooding depth. Output from this modeling effort can provide many useful information for flood planning such as flow depth in main channel, flooding depth and area in interior floodplain. The method was applied to Sapgyo river basin and the comparison with observed flood events showed that it can reproduce the observation fairly well, hence proving the utility of the method.

A Simple Design of an Imaging System for Accurate Spatial Mapping of Blood Oxygen Saturation Using a Single Element of Multi-wavelength LED (혈중 산소 포화도의 정확한 공간 매핑을 위한 다중 파장 LED 단일소자를 활용한 이미징 시스템 설계)

  • Jun Hwan Kim;Gi Yeon Yu;Ye Eun Song;Chan Yeong Yu;Yun Chae Jang;Riaz Muhammad;Kay Thwe Htun;Ahmed Ali;Seung Ho Choi
    • Journal of Biomedical Engineering Research
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    • v.44 no.6
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    • pp.450-464
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    • 2023
  • Pulse oximetry, a non-invasive technique for evaluating blood oxygen saturation, conventionally depends on isolated measurements, rendering it vulnerable to factors like illumination profile, spatial blood flow fluctuations, and skin pigmentation. Previous efforts to address these issues through imaging systems often employed red and near-infrared illuminations with distinct profiles, leading to inconsistent ratios of transmitted light and the potential for errors in calculating spatial oxygen saturation distributions. While an integrating sphere was recently utilized as an illumination source to achieve uniform red and near-infrared illumination profiles on the sample surface, its bulkiness presented practical challenges. In this work, we have enhanced the pulse oximetry imaging system by transitioning illumination from an integrating sphere to a multi-wavelength LED configuration. This adjustment ensures simultaneous emission of red and near-infrared light from the same position, creating a homogeneous illumination profile on the sample surface. This approach guarantees consistent patterns of red and near-infrared illuminations that are spatially uniform. The sustained ratio between transmitted red and near-infrared light across space enables precise calculation of the spatial distribution of oxygen saturation, making our pulse oximetry imaging system more compact and portable without compromising accuracy. Our work significantly contributes to obtaining spatial information on blood oxygen saturation, providing valuable insights into tissue oxygenation in peripheral regions.

Strategies for Managing Dementia Patients through Improving Oral Health and Occlusal Rehabilitation: A Review and Meta-analysis

  • Yeon-Hee Lee;Sung-Woo Lee;Hak Young Rhee;Min Kyu Sim;Su-Jin Jeong;Chang Won Won
    • Journal of Korean Dental Science
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    • v.16 no.2
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    • pp.128-148
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    • 2023
  • Dementia is an umbrella term that describes the loss of thinking, memory, attention, logical reasoning, and other mental abilities to the extent that it interferes with the activities of daily living. More than 50 million individuals worldwide live with dementia, which is expected to increase to 131 million by 2050. Recent research has shown that poor oral health increases the risk of dementia, while oral health declines with cognitive decline. In this narrative review, the literature was based on the "hypothesis" that dementia and oral health have a close relationship, and appropriate oral health and occlusal rehabilitation treatment can improve the quality of life of patients with dementia and prevent progression. We conducted a literature search in PubMed and Google Scholar databases, using the search terms "dementia," "major neurocognitive disorder," "dentition," "occlusion," "tooth loss," "dental prosthesis," "dental implant," and "occlusal rehabilitation" in the title field over the past 30 years. A total of 131 studies that scientifically addressed dementia, oral health, and/or oral rehabilitation were included. In a meta-analysis, the random effect model demonstrated significant tooth loss increasing the dementia risk 3.64-fold (pooled odds ratio=3.64, 95% confidence interval [2.50~5.32], P-value=0.0348). Tooth loss can be an important indicator of cognitive function decline. As the number of missing teeth increases, the risk of dementia increases. Loss of teeth can lead to a decrease in the ascending information to the brain and reduced masticatory ability, cerebral blood flow, and psychological atrophy. Oral microbiome dysbiosis and migration of key bacterial species to the brain can also cause dementia. Additionally, inflammation in the oral cavity affects the inflammatory response of the brain and the complete body. Conversely, proper oral hygiene management, the placement of dental implants or prostheses to replace lost teeth, and the restoration of masticatory function can inhibit symptom progression in patients with dementia. Therefore, improving oral health can prevent dementia progression and improve the quality of life of patients.

Investigation of thermal hydraulic behavior of the High Temperature Test Facility's lower plenum via large eddy simulation

  • Hyeongi Moon ;Sujong Yoon;Mauricio Tano-Retamale ;Aaron Epiney ;Minseop Song;Jae-Ho Jeong
    • Nuclear Engineering and Technology
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    • v.55 no.10
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    • pp.3874-3897
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    • 2023
  • A high-fidelity computational fluid dynamics (CFD) analysis was performed using the Large Eddy Simulation (LES) model for the lower plenum of the High-Temperature Test Facility (HTTF), a ¼ scale test facility of the modular high temperature gas-cooled reactor (MHTGR) managed by Oregon State University. In most next-generation nuclear reactors, thermal stress due to thermal striping is one of the risks to be curiously considered. This is also true for HTGRs, especially since the exhaust helium gas temperature is high. In order to evaluate these risks and performance, organizations in the United States led by the OECD NEA are conducting a thermal hydraulic code benchmark for HTGR, and the test facility used for this benchmark is HTTF. HTTF can perform experiments in both normal and accident situations and provide high-quality experimental data. However, it is difficult to provide sufficient data for benchmarking through experiments, and there is a problem with the reliability of CFD analysis results based on Reynolds-averaged Navier-Stokes to analyze thermal hydraulic behavior without verification. To solve this problem, high-fidelity 3-D CFD analysis was performed using the LES model for HTTF. It was also verified that the LES model can properly simulate this jet mixing phenomenon via a unit cell test that provides experimental information. As a result of CFD analysis, the lower the dependency of the sub-grid scale model, the closer to the actual analysis result. In the case of unit cell test CFD analysis and HTTF CFD analysis, the volume-averaged sub-grid scale model dependency was calculated to be 13.0% and 9.16%, respectively. As a result of HTTF analysis, quantitative data of the fluid inside the HTTF lower plenum was provided in this paper. As a result of qualitative analysis, the temperature was highest at the center of the lower plenum, while the temperature fluctuation was highest near the edge of the lower plenum wall. The power spectral density of temperature was analyzed via fast Fourier transform (FFT) for specific points on the center and side of the lower plenum. FFT results did not reveal specific frequency-dominant temperature fluctuations in the center part. It was confirmed that the temperature power spectral density (PSD) at the top increased from the center to the wake. The vortex was visualized using the well-known scalar Q-criterion, and as a result, the closer to the outlet duct, the greater the influence of the mainstream, so that the inflow jet vortex was dissipated and mixed at the top of the lower plenum. Additionally, FFT analysis was performed on the support structure near the corner of the lower plenum with large temperature fluctuations, and as a result, it was confirmed that the temperature fluctuation of the flow did not have a significant effect near the corner wall. In addition, the vortices generated from the lower plenum to the outlet duct were identified in this paper. It is considered that the quantitative and qualitative results presented in this paper will serve as reference data for the benchmark.

A Framework Development for Sketched Data-Driven Building Information Model Creation to Support Efficient Space Configuration and Building Performance Analysis (효율적 공간 형상화 및 건물성능분석을 위한 스케치 정보 기반 BIM 모델 자동생성 프레임워크 개발)

  • Kong, ByungChan;Jeong, WoonSeong
    • Korean Journal of Construction Engineering and Management
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    • v.25 no.1
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    • pp.50-61
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    • 2024
  • The market for compact houses is growing due to the demand for floor plans prioritizing user needs. However, clients often have difficulty communicating their spatial requirements to professionals including architects because they lack the means to provide evidence, such as spatial configurations or cost estimates. This research aims to create a framework that can translate sketched data-driven spatial requirements into 3D building components in BIM models to facilitate spatial understanding and provide building performance analysis to aid in budgeting in the early design phase. The research process includes developing a process model, implementing, and validating the framework. The process model describes the data flow within the framework and identifies the required functionality. Implementation involves creating systems and user interfaces to integrate various systems. The validation verifies that the framework can automatically convert sketched space requirements into walls, floors, and roofs in a BIM model. The framework can also automatically calculate material and energy costs based on the BIM model. The developed frame enables clients to efficiently create 3D building components based on the sketched data and facilitates users to understand the space and analyze the building performance through the created BIM models.

New Method for Combined Quantitative Assessment of Air-Trapping and Emphysema on Chest Computed Tomography in Chronic Obstructive Pulmonary Disease: Comparison with Parametric Response Mapping

  • Hye Jeon Hwang;Joon Beom Seo;Sang Min Lee;Namkug Kim;Jaeyoun Yi;Jae Seung Lee;Sei Won Lee;Yeon-Mok Oh;Sang-Do Lee
    • Korean Journal of Radiology
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    • v.22 no.10
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    • pp.1719-1729
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    • 2021
  • Objective: Emphysema and small-airway disease are the two major components of chronic obstructive pulmonary disease (COPD). We propose a novel method of quantitative computed tomography (CT) emphysema air-trapping composite (EAtC) mapping to assess each COPD component. We analyzed the potential use of this method for assessing lung function in patients with COPD. Materials and Methods: A total of 584 patients with COPD underwent inspiration and expiration CTs. Using pairwise analysis of inspiration and expiration CTs with non-rigid registration, EAtC mapping classified lung parenchyma into three areas: Normal, functional air trapping (fAT), and emphysema (Emph). We defined fAT as the area with a density change of less than 60 Hounsfield units (HU) between inspiration and expiration CTs among areas with a density less than -856 HU on inspiration CT. The volume fraction of each area was compared with clinical parameters and pulmonary function tests (PFTs). The results were compared with those of parametric response mapping (PRM) analysis. Results: The relative volumes of the EAtC classes differed according to the Global Initiative for Chronic Obstructive Lung Disease stages (p < 0.001). Each class showed moderate correlations with forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity (FVC) (r = -0.659-0.674, p < 0.001). Both fAT and Emph were significant predictors of FEV1 and FEV1/FVC (R2 = 0.352 and 0.488, respectively; p < 0.001). fAT was a significant predictor of mean forced expiratory flow between 25% and 75% and residual volume/total vital capacity (R2 = 0.264 and 0.233, respectively; p < 0.001), while Emph and age were significant predictors of carbon monoxide diffusing capacity (R2 = 0.303; p < 0.001). fAT showed better correlations with PFTs than with small-airway disease on PRM. Conclusion: The proposed quantitative CT EAtC mapping provides comprehensive lung functional information on each disease component of COPD, which may serve as an imaging biomarker of lung function.

Evaluation of Hydrogeological Characteristics of Deep-Depth Rock Aquifer in Volcanic Rock Area (화산암 지역 고심도 암반대수층 수리지질특성 평가)

  • Hangbok Lee;Chan Park;Junhyung Choi;Dae-Sung Cheon;Eui-Seob Park
    • Tunnel and Underground Space
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    • v.34 no.3
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    • pp.231-247
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    • 2024
  • In the field of high-level radioactive waste disposal targeting deep rock environments, hydraulic characteristic information serves as the most important key factor in selecting relevant disposal sites, detailed design of disposal facilities, derivation of optimal construction plans, and safety evaluation during operation. Since various rock types are mixed and distributed in a small area in Korea, it is important to conduct preliminary work to analyze the hydrogeological characteristics of rock aquifers for various rock types and compile the resulting data into a database. In this paper, we obtained hydraulic conductivity data, which is the most representative field hydraulic characteristic of a high-depth volcanic bedrock aquifer, and also analyzed and evaluated the field data. To acquire field data, we used a high-performance hydraulic testing system developed in-house and applied standardized test methods and investigation procedures. In the process of hydraulic characteristic data analysis, hydraulic conductivity values were obtained for each depth, and the pattern of groundwater flow through permeable rock joints located in the test section was also evaluated. It is expected that the series of data acquisition methods, procedures, and analysis results proposed in this report can be used to build a database of hydraulic characteristics data for high-depth rock aquifers in Korea. In addition, it is expected that it will play a role in improving technical know-how to be applied to research on hydraulic characteristic according to various bedrock types in the future.

The Impacts of Need for Cognitive Closure, Psychological Wellbeing, and Social Factors on Impulse Purchasing (인지폐합수요(认知闭合需要), 심리건강화사회인소대충동구매적영향(心理健康和社会因素对冲动购买的影响))

  • Lee, Myong-Han;Schellhase, Ralf;Koo, Dong-Mo;Lee, Mi-Jeong
    • Journal of Global Scholars of Marketing Science
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    • v.19 no.4
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    • pp.44-56
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    • 2009
  • Impulse purchasing is defined as an immediate purchase with no pre-shopping intentions. Previous studies of impulse buying have focused primarily on factors linked to marketing mix variables, situational factors, and consumer demographics and traits. In previous studies, marketing mix variables such as product category, product type, and atmospheric factors including advertising, coupons, sales events, promotional stimuli at the point of sale, and media format have been used to evaluate product information. Some authors have also focused on situational factors surrounding the consumer. Factors such as the availability of credit card usage, time available, transportability of the products, and the presence and number of shopping companions were found to have a positive impact on impulse buying and/or impulse tendency. Research has also been conducted to evaluate the effects of individual characteristics such as the age, gender, and educational level of the consumer, as well as perceived crowding, stimulation, and the need for touch, on impulse purchasing. In summary, previous studies have found that all products can be purchased impulsively (Vohs and Faber, 2007), that situational factors affect and/or at least facilitate impulse purchasing behavior, and that various individual traits are closely linked to impulse buying. The recent introduction of new distribution channels such as home shopping channels, discount stores, and Internet stores that are open 24 hours a day increases the probability of impulse purchasing. However, previous literature has focused predominantly on situational and marketing variables and thus studies that consider critical consumer characteristics are still lacking. To fill this gap in the literature, the present study builds on this third tradition of research and focuses on individual trait variables, which have rarely been studied. More specifically, the current study investigates whether impulse buying tendency has a positive impact on impulse buying behavior, and evaluates how consumer characteristics such as the need for cognitive closure (NFCC), psychological wellbeing, and susceptibility to interpersonal influences affect the tendency of consumers towards impulse buying. The survey results reveal that while consumer affective impulsivity has a strong positive impact on impulse buying behavior, cognitive impulsivity has no impact on impulse buying behavior. Furthermore, affective impulse buying tendency is driven by sub-components of NFCC such as decisiveness and discomfort with ambiguity, psychological wellbeing constructs such as environmental control and purpose in life, and by normative and informational influences. In addition, cognitive impulse tendency is driven by sub-components of NFCC such as decisiveness, discomfort with ambiguity, and close-mindedness, and the psychological wellbeing constructs of environmental control, as well as normative and informational influences. The present study has significant theoretical implications. First, affective impulsivity has a strong impact on impulse purchase behavior. Previous studies based on affectivity and flow theories proposed that low to moderate levels of impulsivity are driven by reduced self-control or a failure of self-regulatory mechanisms. The present study confirms the above proposition. Second, the present study also contributes to the literature by confirming that impulse buying tendency can be viewed as a two-dimensional concept with both affective and cognitive dimensions, and illustrates that impulse purchase behavior is explained mainly by affective impulsivity, not by cognitive impulsivity. Third, the current study accommodates new constructs such as psychological wellbeing and NFCC as potential influencing factors in the research model, thereby contributing to the existing literature. Fourth, by incorporating multi-dimensional concepts such as psychological wellbeing and NFCC, more diverse aspects of consumer information processing can be evaluated. Fifth, the current study also extends the existing literature by confirming the two competing routes of normative and informational influences. Normative influence occurs when individuals conform to the expectations of others or to enhance his/her self-image. Whereas informational influence occurs when individuals search for information from knowledgeable others or making inferences based upon observations of the behavior of others. The present study shows that these two competing routes of social influence can be attributed to different sources of influence power. The current study also has many practical implications. First, it suggests that people with affective impulsivity may be primary targets to whom companies should pay closer attention. Cultivating a more amenable and mood-elevating shopping environment will appeal to this segment. Second, the present results demonstrate that NFCC is closely related to the cognitive dimension of impulsivity. These people are driven by careless thoughts, not by feelings or excitement. Rational advertising at the point of purchase will attract these customers. Third, people susceptible to normative influences are another potential target market. Retailers and manufacturers could appeal to this segment by advertising their products and/or services as products that can be used to identify with or conform to the expectations of others in the aspiration group. However, retailers should avoid targeting people susceptible to informational influences as a segment market. These people are engaged in an extensive information search relevant to their purchase, and therefore more elaborate, long-term rational advertising messages, which can be internalized into these consumers' thought processes, will appeal to this segment. The current findings should be interpreted with caution for several reasons. The study used a small convenience sample, and only investigated behavior in two dimensions. Accordingly, future studies should incorporate a sample with more diverse characteristics and measure different aspects of behavior. Future studies should also investigate personality traits closely related to affectivity theories. Trait variables such as sensory curiosity, interpersonal curiosity, and atmospheric responsiveness are interesting areas for future investigation.

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