Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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1223 research outputs found
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Seismic Retrofit of Central Opening Partial Infilled Frame by Expanded Metal Ferrocement
Full text linkThis paper presents the retrofit of partial infilled frame with central opening by ferrocement and expanded metal. Theoretical models are suggested to design the lateral resistance of the retrofitted frames. Experimental tests on the prototype frames were carried out to verify the design method. Four specimens were built to the full scale, which were divided into two groups: a) the bare frame and the retrofitted frame, and b) the partial infilled frame with window opening and the retrofitted frame. It was found that the retrofitted frame with window opening showed satisfactory behaviors including the lateral strength, lateral stiffness and energy dissipation capacity. The observed maximum lateral strength of the retrofitted frame with opening achieved the design strength. The proposed model predicted the lateral strength with a good accuracy when it was compared with the experimental result. The strengthened columns for the opening infilled frame prevented brittle shear failure due to the behavior of short column. The retrofitted column exhibited a ductile behavior with the developed flexural crack at the constrained level
Effect of Extractant pH and Concentration of Ageratum Conyziodes L on the Optical Properties of Photosensitizer and Performance of Dye-Sensitized Solar Cell
No full textA dye-sensitized Solar Cell (DSSC) is a type of third-generation solar cell that uses dye as a light-sensitizing layer and is still under development. DSSC offers several advantages over previous generations, such as low production costs, simple manufacturing processes, and environmental friendliness, non-toxic and lightweight. However, in its development, natural dyes are derived from natural materials. This study focused on the optical properties and performance of DSSC as affected by variations in solvent pH and concentration of Ageratum conyzoides L. In this study, the pH of the solvent was varied at pH 1.00, 1.66, 2.27, and 3.00. Dye with solvent pH that has the best efficiency was then varied in concentration to 1.25gr/50ml, 2.5gr/50ml, 3.75gr/50ml, and 5gr/50ml. Fourier Transform Infrared (FTIR) characterization was used to identify the pigments contained in the dye. Raman spectroscopy, UV-Vis spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and J-V characteristic measurements were performed to analyze the optical properties and performance of the DSSC. The results showed that the dye sample in pH 1.00 solvent with 2,5gr/50ml concentration had the best performance with an average. , 0.525 V, 58.4%, and an average efficiency 0.000598%. Although the DSSC in this study is less efficient than the typical efficiencies of 3-12% reported for natural dye-based DSSCs, this work highlights critical parameters such as solvent pH and dye concentration that influence performance. The results provide insights into addressing the inherent limitations of natural dyes in renewable energy applications, contributing to the ongoing advancements in environmentally friendly and sustainable solar energy technologies through the optimized use of natural dyes in DSSCs
Ex-post Evaluation Framework of Transportation Infrastructure Projects in Thailand Applying the OECD-DAC's Evaluation Criteria
No full textEx-post evaluations are conducted only on rare occasions despite their significant potential for utility. Such evaluations ascertain whether projects have fulfilled the anticipated benefits at the outset and discern which projects have outperformed or underperformed expectations, along with the underlying reasons. This paper describes the methodological framework chosen for the ex-post evaluation of completed transportation infrastructure projects. A comprehensive framework assessing the effects of a transport project across six dimensions: Relevance, Coherence, Effectiveness, Efficiency, Impact, and Sustainability has been formulated and elaborated as part of an ex-post evaluation methodology. This framework encompasses a classification of impacts associated with investment projects in the transportation sector. Then, the framework for the ex-post evaluation was applied to evaluate the case studies of seven highway projects executed by the Department of Highway, Ministry of Transport, Thailand. The ex-post evaluation results for these case studies found that seven projects were ranked at a very good level. The criteria of efficiency were the aspect with the highest score from the evaluation results, as four projects out of 7 had a total score of 4.00, reflecting the performance of the Department of Highways in using available resources in terms of time and budget efficiently in project development. The criteria of relevance and coherence, as the implementation of the Department of Highways project development, has been consistent with the national development plan, ministry level, and department level and linked to other essential development plans of the country. Meanwhile, effectiveness, impact, and sustainability were criteria with different scores for each project
Employment and Human Development for Foreign Civil Engineer in Japanese Construction Industries
No full textThis thesis extracts the facts and issues on employment and human development for foreign civil engineer in Japanese construction industries and proposes the solutions to potential future problems. Compared to other industries, aging of workers and engineers in construction industries has been ongoing rapidly. And Japanese construction industries require recruitment foreign skilled workers and civil engineers to make up this shortage of workers and engineers. This thesis focuses on foreign civil engineers and studies issues from the both sides of foreign civil engineers and Japanese employers. Additionally, it proposes sustainable solution for Japanese construction industries to achieve long term employment of foreign civil engineers. Especially, Japan’s qualifications processes and multi-layered subcontractor system composed of prime contractors and lower subcontractors are highlighted as important points of foreign civil engineers. Interviews on foreign civil engineers and their Japanese managers and management personnels were taken place and collected data such as reasons of preference of Japanese contractors, motivations, career development plan from foreign civil engineers, and recruitment criteria, promotion system, training and education programs from their Japanese managers and management personnels. Based on these data and studies, this thesis analyses and concludes key solutions on long term employment and human development for foreign civil engineers in Japanese construction industries
Estimation of Hydraulic Power Take-Off Parameters in a Floating Absorber Type Wave Energy Converter Using the Genetic Algorithm Method
No full textA Wave Energy Converter (WEC) harnesses ocean wave motion to generate electrical energy, with the Hydraulic Power Take-Off (HPTO) system playing a crucial role in converting this motion into usable power. This study explores the use of the Genetic Algorithm (GA) to optimize key HPTO parameters. By mimicking the process of natural evolution, GA effectively estimates the optimal parameters for enhancing system performance. The research demonstrates that a hydraulic motor with a displacement of 71 cc/rev, under an input force of 40,000 N, produced 41.5 kW in a single-point configuration and 104 kW in a multi-point setup, emphasizing the importance of selecting the right motor displacement. Furthermore, increasing the number of absorbers in the system significantly boosted overall performance, with the multi-point configuration showing superior energy capture and mechanical power output. These findings highlight the critical role of optimization and system configuration in improving HPTO efficiency and offer valuable insights for future WEC designs aimed at maximizing energy conversion
FPGA Implementation of Phase Noise Equalization for High Speed 5G OFDM using Parallel Processing Algorithm
No full textPhase noise significantly degrades the system performance in high-speed 5G orthogonal frequency division multiplexing (OFDM) systems, particularly within the challenging FR2 band, which can support up to 400 MHz of bandwidth. As a result, efficient cancellation techniques for phase noise are necessary. This paper introduces an effective field-programmable gate array (FPGA) implementation for phase noise cancellation in 5G OFDM. To address the inherent limitations in FPGA clock speed at high data rates, parallel processing is employed. Additionally, a novel complex multiplication optimization is presented, which significantly reduces logic gate usage and enhances hardware efficiency compared to standard methods. The effectiveness of the proposed maximum likelihood estimation (MLE) based approach is confirmed through simulations and real-time testing on a Virtex-7 FPGA. The results show excellent agreement between simulation and hardware, with significant phase noise reduction and bit error rates (BER) below 10−3 for 16-QAM and 64-QAM, and 10−2 for 256-QAM. The implementation is highly efficient, using only 3% of FPGA slices, demonstrating its practical feasibility for 5G FR2 deployments
Evaluation of Extraction Solvents and Hydrolysis Methods for Efficient Recovery of Ferulic Acid from Rice Bran
Full text linkWater Quality Control and Aquaculture Pond Feeding System with Internet of Things Technology
Full text linkThis research explores a water quality control and feeding system for aquaculture ponds using Internet of Things technology. Aquaculture is a major economic activity in Thailand, but maintaining optimal water quality is crucial for the health and growth of aquatic animals. The system consists of three key components: sensors for monitoring water parameters (temperature, pH, turbidity, and dissolved oxygen), a NodeMCU ESP32 microcontroller for data processing, and a web application for user interaction. Water quality is regulated through automatic control of pumps that manage water exchange when parameters exceed safe thresholds, while an automated feeding system dispenses food based on user-set schedules or manual controls. Real-time data is displayed on the web application, which allows users to monitor sensor readings, control operations, and generate reports. The system supports both automatic and manual modes and includes features for user authentication, data logging, and export options. Performance evaluations demonstrated the system’s effectiveness in maintaining water quality and automating feeding processes, meeting the needs of aquaculture farmers efficiently
Assessing the Effect of Rain Shelter Cultivation System on Corn (Zea Mays L.) with Fertilizer Treatment Based on Leaf Color : A Classification Approach
Full text linkThe use of rain shelters is intended to prevent corn plant flowers from being miscarried because of high rainfall. However, the effects of rain shelters on corn growth have not been explored. Therefore, this study analyzed the growth of maize using rain shelters based on leaf color. One-way farmers can identify corn fertility by making visual observations using leaf color charts. However, this method is prone to misinterpretation owing to farmer subjectivity. Several studies have developed various methods to overcome these problems; however, these methods require expensive and complex equipment and specialized user competence. Therefore, this study proposes a classification system for corn plant fertility based on leaf images using the CNN ResNet50 architecture with an image enhancement process. The proposed method uses a smartphone camera with additional microlens during the image-acquisition process. The proposed method can provide a loss value of 15.16%, accuracy of 95.35%, precision of 95.35%, recall of 95.25%, AUC of 98.48%, and F1-Score of 95.33%; the computation time of the training process is 1075.94 seconds. The test results demonstrated that the proposed method can accurately classify the treatment of corn plants using rain shelter
Analysis of Faulted Overhead Distribution Systems Using Linearization Method
Full text linkFaulted overhead distribution systems can be analyzed for fault diagnosis and protection planning using MATLAB/Simulink; however, for large-scale systems or detailed fault modeling, this approach may require significant computational time. In this paper, we propose a novel algorithm based on linearization techniques to expedite fault analysis. The algorithm modifies the system's admittance matrix, incorporating fault type, location, and admittance values, alongside models for neutral and ground conductors, distribution transformers, and loads represented as R–L elements. By linearizing the system equations, the proposed method enables faster analysis while maintaining accuracy under complex fault scenarios, such as simultaneous or asymmetrical faults. Comparative evaluations with MATLAB/Simulink demonstrate the algorithm's efficiency in reducing computation time for fault analysis