• Computers and Concrete
• /
• 제14권6호
• /
• pp.745-765
• /
• 2014

In this paper, it is aimed to determine the finite element model updating effects on the structural behavior of long span concrete highway bridges. Birecik Highway Bridge located on the 81stkm of Sanliurfa-Gaziantep state highway over Firat River in Turkey is selected as a case study. The bridge consist of fourteen spans, each of span has a nearly 26m. The total bridge length is 380m and width of bridge is 10m. Firstly, the analytical dynamic characteristics such as natural frequencies and mode shapes are attained from finite element analyses using SAP2000 program. After, experimental dynamic characteristics are specified from field investigations using Operational Modal Analysis method. Enhanced Frequency Domain Decomposition method in the frequency domain is used to extract the dynamic characteristics such as natural frequencies, mode shapes and damping ratios. Analytically and experimentally identified dynamic characteristics are compared with each other and finite element model of the bridge is updated to reduce the differences by changing of some uncertain parameters such as section properties, damages, boundary conditions and material properties. At the end of the study, structural performance of the highway bridge is determined under dead load, live load, and dynamic loads before and after model updating to specify the updating effect. Displacements, internal forces and stresses are used as comparison parameters. From the study, it is seen that the ambient vibration measurements are enough to identify the most significant modes of long span highway bridges. Maximum differences between the natural frequencies are reduced averagely from %46.7 to %2.39 by model updating. A good harmony is found between mode shapes after finite element model updating. It is demonstrated that finite element model updating has an important effect on the structural performance of the arch type long span highway bridge. Maximum displacements, shear forces, bending moments and compressive stresses are reduced %28.6, %21.0, %19.22, and %33.3-20.0, respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제18권4호
• /
• pp.980-997
• /
• 2024

To improve the brightness of images and reveal hidden information in dark areas is the main objective of low-light image enhancement (LLIE). LLIE methods based on deep learning show good performance. However, there are some limitations to these methods, such as the complex network model requires highly configurable environments, and deficient enhancement of edge details leads to blurring of the target content. Single-scale feature extraction results in the insufficient recovery of the hidden content of the enhanced images. This paper proposed an edge detection-based multi-scale feature enhancement network for LLIE (EDMFEN). To reduce the loss of edge details in the enhanced images, an edge extraction module consisting of a Sobel operator is introduced to obtain edge information by computing gradients of images. In addition, a multi-scale feature enhancement module (MSFEM) consisting of multi-scale feature extraction block (MSFEB) and a spatial attention mechanism is proposed to thoroughly recover the hidden content of the enhanced images and obtain richer features. Since the fused features may contain some useless information, the MSFEB is introduced so as to obtain the image features with different perceptual fields. To use the multi-scale features more effectively, a spatial attention mechanism module is used to retain the key features and improve the model performance after fusing multi-scale features. Experimental results on two datasets and five baseline datasets show that EDMFEN has good performance when compared with the stateof-the-art LLIE methods.

• 한국통신학회논문지
• /
• 제17권8호
• /
• pp.779-788
• /
• 1992

일반적으로 높은 성능의 컴퓨터 시스템은 입력/출력 서브시스템에서 자주 병목현상이 나타난다. 일반적으로 시스템 성능평가 모델은 I/O 시스템의 영향을 포함하여 다루어진다. 본 논문에서는 컴퓨터 자원의 분배에 필수적인 장치인 터미널 서버를 모델링 하여 연구한다. 시스템 성능의 주요 요소를 찾아 보기 위해 M/M/I 큐잉 모델을 사용한다. 터미널 서버의 FIFO버퍼 크기는 시스템 설계에 중요 요소이며 전체 시스템 성능에 영향을 비칠 수 있다. 본 논문에서는 시스템 성능을 향상 시키기 위해 터미널 서버모델의 최적 버퍼 크기를 제시한다. 또한 큐잉 모델을 이용하여 터미널서버의 지연시간을 분석하고 시뮬레이션 결과에서 참조 모델을 찾는다.

• 한국분무공학회지
• /
• 제24권3호
• /
• pp.105-113
• /
• 2019

In this paper, a study of Urea-SCR System for Dosing Injector for responding to enhanced environmental regulations has been conducted. There is a limit to the experimental approach due to the structural characteristics of the injector. In order to overcome this problem, The analysis was performed assuming unsteady turbulent flow through computational fluid analysis and the internal flow characteristics of the injector were analyzed. By changing the nozzle shape of the injector, the performance factors of the swirl injector by shape were selected and compared. The design parameters were modified by changing the diameter of the nozzle at a constant ratio compared to the base model. Swirl coefficient, outlet mass flow, and sac volume were selected as performance parameters of the injector. The Conv. model to which the taper was applied showed the dominance in mass flow rate, discharge coefficient and swirl because of the smooth fluid flow by shape. Swirl coefficient, outlet mass flow, and sac volume were selected as performance parameters of the injector. As a result of the comparison coefficient derivation with those performance parameters for comparing the performance of the model-specific injector, the Conv-140 model with the nozzle diameter expanded by 140% showed the best value of the comparison coefficient.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2011년도 학술발표회
• /
• pp.19-19
• /
• 2011

The appraisals of hydrology model behavior for flow and water quality are generally performed through comparison of simulated data with observed ones. To perform appraisal of hydrology model, some criteria are often used, such as coefficient of determination ($R^2$), Nash and Sutcliffe model efficiency coefficient (NSE), index of agreement (d), modified forms of NSE and d, and relative efficiency criteria NSE and d. These criteria are used not only for hydrology model estimations also for various comparisons of two data sets; This NSE has been often used for SWAT calibration. However, it has been known that the NSE value has some limitations in evaluating hydrology at watersheds under monsoon climate because this statistic is largely affected by higher values in the data set. To overcome these limitations, the SWAT auto-calibration module was enhanced with K-means clustering and direct runoff/baseflow modules. However the NSE is still being used in this module to evaluate model performance. Therefore, the SWAT Auto-calibration module was modified to incorporate alternative efficiency criteria into the SWAT K-means/direct runoff-baseflow auto-calibration module. It is expected that this enhanced SWAT auto-calibration module will provide better calibration capability of SWAT model for all flow regime.

• 품질경영학회지
• /
• 제42권4호
• /
• pp.617-632
• /
• 2014

Purpose: This study aims to explore the relationship between the focal firm's interdepartmental cooperation and new product development (NPD) performance with focus on the moderating effect of environmental uncertainty. The basic hypothesized model is that there are positively associated relationships. Methods: The proposed research model was tested using structural equation modeling with 601 responses from multi-functional and multiple respondents in Korean manufacturing firms. Multi-group SEM analyses were conducted to explore the degree to which the hypothesized model was equivalent for different levels of environmental uncertainty. Results: Interdepartmental cooperation between R&D and production is positively associated with NPD performance under both higher and lower environmental uncertainties, while one between R&D and marketing is positively associated under only higher environmental uncertainty. Conclusion: This paper determined that NPD performance is positively correlated with R&D-production cooperation in a focal firm, and the relationship between R&D-marketing cooperation and NPD performance is positively moderated by level of environmental uncertainty. Consequently, this study suggests that it is always important for firms to put much effort on R&D-production cooperation for a better NPD performance, while R&D-marketing cooperation should be enhanced especially under higher environmental uncertainty than lower.

• ETRI Journal
• /
• 제43권5호
• /
• pp.825-834
• /
• 2021

Based on its simplicity and user-friendly characteristics, OpenMP has become the standard model for programming on shared-memory architectures. Checkpointing-aided parallel execution (CAPE) is an approach that utilizes the discontinuous incremental checkpointing technique (DICKPT) to translate and execute OpenMP programs on distributed-memory architectures automatically. Currently, CAPE implements the OpenMP execution model by utilizing the DICKPT to distribute parallel jobs and their data to slave machines, and then collects the results after executing these distributed jobs. Although this model has been proven to be effective in terms of performance and compatibility with OpenMP on distributed-memory systems, it cannot fully exploit the capabilities of multicore processors. This paper presents a novel execution model for CAPE that utilizes two levels of parallelism. In the proposed model, we add another level of parallelism in the form of multithreaded processes on slave machines with the goal of better exploiting their multicore CPUs. Initial experimental results presented near the end of this paper demonstrate that this model provides significantly enhanced CAPE performance.

• 통상정보연구
• /
• 제12권1호
• /
• pp.271-295
• /
• 2010

In this study, we investigate the relationships among organizational market orientation, learning orientation, information technology(IT) support for firm resource, IT support for strategy, and balanced scorecard(BSC) performance in export firms. The development of the research model is based on the empirical studies of strategy and resource-based view. The data from the survey was analyzed using Partial Least Squares(PLS). The results from the empirical model suggest that IT support for firm resource is effected by market orientation and learning orientation. And, IT support for strategy is enhanced by IT support for firm resource. Finally, BSC performance of export firms is effected by IT support for strategy.

• 통상정보연구
• /
• 제12권3호
• /
• pp.311-332
• /
• 2010

This study investigate the effects of environmental and organizational characteristics on e-business competence and the influence of e-business competence on export performance in the small and medium sized firms. The development of the research model is based on the literature of e-business and the empirical studies of information technology competence. The data from the survey was analyzed using Partial Least Squares(PLS). The results from the empirical model suggest that e-business competence is affected by environmental uncertainty and market diversity as well as top management support and learning orientation. And, export performance is enhanced by e-business competence.

• 전기학회논문지
• /
• 제65권4호
• /
• pp.652-658
• /
• 2016

In practical control systems differences between nominal and real systems arise from internal uncertainties and/or external disturbances. This paper presents a model-based low-order disturbance observer for a sinusoidal disturbance with unknown constant offset. By using the disturbance model of a biased harmonic signal, the proposed method can successfully estimate the biased sinusoidal disturbance with unknown amplitude and phase but known frequency. At the first stage of the observer design, a model-based disturbance observer is designed when all the system states are measurable. Next, a sufficient condition is presented for the proposed observer to estimate the sinusoidal disturbance with a minimal-order additional dynamics using only output measurement. Comparative computer simulations are performed to test the performance of the proposed method. The simulation results show the enhanced performance of the proposed disturbance observer.