• Journal of Power System Engineering
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• v.13 no.1
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• pp.46-52
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• 2009

The steel impeller placed in a water pump has been studied with the aim to understand corrosion phenomena on the surface responsible for reducing the pumping efficiency of water inside cooling system. This preliminary experiment includes a period (over 5 months) observation with a powered microscope and weight measurements. The experiments are carried out at different conditions of water and mixtures of water and coolants, based on the water contents of 25%, 50%, 75%, and 100% water (pure tap water). From the visual results of microscopy, most of the steel surface is fitted and clear rusty or corrosion phenomena are noticeable as time goes. In addition, the weight loss of the sample specimen submerged in the water is linearly increased, whereas those in the mixtures of water initially be constant and then gain weight linearly.

• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.539-558
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• 2012

The diagnosis of bridge serviceability is carried out by a combination of in-situ visual inspection, static and dynamic loading tests and analyses. Structural health monitoring (SHM) using information technology and sensors is increasingly being used for providing a better estimate of structural performance characteristics rather than above traditional methods. Because the mechanical behavior of bridges with various kinds of damage can not be made clear, it is very difficult to estimate both the damage mode and degree of damage of existing bridges. In this paper, the sensitivity of both static and dynamic behaviors of bridges are studied as a measure of damage assessment through experiments on model bridges induced with some specified artificial damages. And, a method of damage assessment of bridges based on those behaviors is discussed in detail. Finally, based on the results, a possible application for structural health monitoring systems for existing bridges is also discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2017-2020
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• 2011

Flicker, which is also known as voltage fluctuation, is an electromagnetic phenomenon generated by large scale nonlinear loads, such as arc furnaces and welding machines. Since a severe and continuous flicker can cause to some damages to electrically sensitive loads as well as human's visual irritations, it needs to be appropriately managed by being accurately measured, quantified and assessed. In Korea, an equivalent 10-Hz flicker index, shortly ${\Delta}V10$, is used to determine the permission limit of flicker. This paper presents an efficient calculation of the flicker index by using a half-cycle sliding window and a recursive method, showing a concrete calculating procedure of ${\Delta}V10$ from the viewpoint of signal processing.

• International Journal of Contents
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• v.11 no.1
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• pp.62-68
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• 2015

Many severe earthquakes have occurred along the main fault lines in the world. In recent years, there has been a high incidence of small- and large-scale earthquakes in our country. These occurrences of earthquakes have become increasingly serious, owing to a degrading earth environment. An earthquake, in general, causes far more serious damages like disruptions in electricity or gas facilities, and fire disasters from its annexed effects than by its vibrations or the shock itself. In this paper, we present a countermeasure and its necessity in safeguarding against fire disasters in regional heritage villages such as "Asan Oeam," "Jeonju Hanok," and "Andong Hahoe." A more systematic and effective strategy for prevention systems against severe fire disasters is proposed after performing various related investigations and analyses of existing domestic and international systems. We investigated the existing fire security systems and their historical records with the tendency of earthquake occurrences in these three folk villages. In this proposal, we present a strategic approach for safeguarding against fire damages in our regional heritage villages derived from ICT (information communication technology)-based DPD (disaster prevention design), after examining the laws and regulations of fire-prevention strategies in Japan, America, and Europe.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.335-340
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• 1996

A green house experiment was conducted to investigate the growth of Chinese cabbage, radish and soybean and change in the chemical properties of the soil after the 10mm application of the simulated acid rain(SAR) of pH 2.7 in the form of sprinkle and mist. It was applied 30 times for Chinese cabbage and radish and 62 times for soybean at the two-day intervals. The results obtained are summarized as follows: 1. Visual damages caused by SAR were dark-brown or red brown leaf spots in Chinese cabbage, and dark-brown and wrinkled leaf margins in radish and soybean. 2. The degree of visual damages became severer as the number of SAR applications increased and it was severer with mist than with sprinkle of SAR. 3. Chlorophyll content was reduced by SAR, but it was not affected by the form of SAR application(sprinkle or mist) in all crops, although it was slightly lower with mist than with sprinkle of SAR. 4. Fresh weight of Chinese cabbage heads and radish roots and grain yield of soybean were reduced by SAR, and were not affected by the form of SAR application. 5. Contents of K, Ca, and Mg in leaves were reduced, while S content increased by SAR in all crops. The forms of SAR application did not affect contents of mineral nutrients in all crops. 6. SAR decreased soil pH and the contents Ca, Mg, and K of soil, while increased $SO_4$ content. However, the contents of soil organic matter, N, and P were not affected by SAR. Forms of SAR application did not affect soil chemical properties either.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.341-347
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• 1996

A green-house experiment was conducted to investigate the growth of Chinese cabbage, radish, and soybean and changes in soil chemical properties after application of 5 and 10mm of pH 2.7 simulated acid rain(SAR) followed by 0, 5, and 10mm of pH 6.0 normal water at the three-day intervals 20 times for Chinese cabbage and radish and 42 times for soybean. The results obtained are summarized as follows: 1. Visual damages by SAR were white-yellow leaf spots, dark brown or light green leaf color, and wrinkled leaf margins in all crops. The degree of visual damages was severer at 10mm than at 5mm SAR and it was reduced as the amounts of normal water increased after SAR application. 2. Chlorophyll content was higher at 10mm than at 5mm SAR application and increased as the amounts of normal water increased after SAR application in all crops. 3. Fresh weights of Chinese cabbage heads and radish roots and grain yield of soybean were higher at 10mm than at 5mm SAR, while they increased as the amounts of normal water increased at the same SAR level. 4. Changes in the mineral contents of plants were not consistent, while S content in radish and soybean increased as the amounts of SAR increased. 5. SAR lowered soil pH, while it increased soil N and S contents. Contents of soil organic matter, P, and exchangeable Ca, Mg, and K were not affected by the amounts of SAR.

• Composites Research
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• v.24 no.1
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• pp.24-30
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• 2011

Low-velocity impact can cause various damages which are mostly hidden inside the laminates or occur in the opposite side. Thus, these damages cannot be easily detected by visual inspection or conventional NDT systems. And if they occurred between the scheduled NDT periods, the possibilities of extensive damages or structural failure can be higher. Due to these reasons, the built-in NDT systems such as real-time impact monitoring system are required in the near future. In this paper, we studied the impact monitoring system consist of impact location detection and damage assessment techniques for composite flat and stiffened panel. In order to acquire the impact-induced acoustic signals, four multiplexed FBG sensors and high-speed FBG interrogator were used. And for development of the impact and damage occurrence detections, the neural networks and wavelet transforms were adopted. Finally, these algorithms were embodied using MATLAB and LabVIEW software for the user-friendly interface.

• Journal of the Korea Institute of Building Construction
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• v.17 no.6
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• pp.545-557
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• 2017

The study is about the efficient alternative to concrete surface in the field of visual inspection technology for deteriorated infrastructure. By combining industrial drones and deep learning based image analysis techniques with traditional visual inspection and research, we tried to reduce manpowers, time requirements and costs, and to overcome the height and dome structures. On board device mounted on drones is consisting of a high resolution camera for detecting cracks of more than 0.3 mm, a lidar sensor and a embeded image processor module. It was mounted on an industrial drones, took sample images of damage from the site specimen through automatic flight navigation. In addition, the damege parts of the site specimen was used to measure not only the width and length of cracks but white rust also, and tried up compare them with the final image analysis detected results. Using the image analysis techniques, the damages of 54ea sample images were analyzed by the segmentation - feature extraction - decision making process, and extracted the analysis parameters using supervised mode of the deep learning platform. The image analysis of newly added non-supervised 60ea image samples was performed based on the extracted parameters. The result presented in 90.5 % of the damage detection rate.

• Journal of Biosystems Engineering
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• v.40 no.4
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• pp.409-416
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• 2015

Purpose: This study evaluates a new banana bulk packaging method under the real transport conditions of Sri Lanka. Methods: A field evaluation of optimized 8-mm thick Styrofoam sheets used as the cushioning material was applied. A trial transport was conducted from Thambuttegama to Colombo using a medium-sized open truck, with banana leaves as the control material. Data were recorded at the farmer, transporter, retailer, and consumer stages of the supply chain. Mechanical damage, physiological loss in weight, fruit firmness, total soluble solids, ripeness index, visual quality ratings, and the physical damage index of the bananas were measured at each stage. A cost-benefit analysis was also conducted for both packaging methods. Results: The 8-mm styrofoam sheets significantly reduced (p < 0.05) the mechanical damage from 26.3% to 12.9% compared to the conventional method for long-distance transport, and the physiological loss in weight showed a decrease of 2.88%. The loss of firmness of the fruits followed a simmilar pattern for both methods until reaching the retailer, but at the consumer was significantly higher (p < 0.05) for the control. However, the physical damage index at the retail stage for the control showed symptoms of physical injury, whereas the bananas transported using the cushioning materials exhibited only minor symptoms. Further, the visual quality of the fruits after transport from the farmer to the consumer was preserved, which is one of the main factors affecting consumer preference and retail price. The proposed method increases the profit margin by 51.2% for Embul bananas owing to the reduced postharvest losses. Conclusion: The 8-mm thick Styrofoam sheets reduced the physical damage to the bananas, with the quality parameters maintained at the prefered level. Moreover, profits may be increased.

• Computers and Concrete
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• v.26 no.3
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• pp.203-211
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• 2020

Turkey is located in one of the most seismically active regions of in Europe. The majority of the population living in big cities are at high seismic risk due to insufficient structural resistance of the existing buildings. Such a seismic risk brings the need for a comprehensive seismic evaluation based on the risk analysis in Turkey. Determining the seismic resistance level of existing building stock against the earthquakes is the first step to reduce the damages in a possible earthquake. Recently in January 2020, the Elazig earthquake brought the importance of the issue again in the public. However, the excessive amount of building stock, labor, and resource problems made the implementation phase almost impossible and revealed the necessity to carry out alternative studies on this issue. This study aims for a detailed investigation of residential buildings in Antalya, Turkey. The approach proposed here can be considered an improved state of building survey methods previously identified in Turkey's Design Code. Antalya, Turkey's fifth most populous city, with a population over 2.5 Million, was investigated as divided into sub-regions to understand the vulnerability, and a threshold value found for the study area. In this study, 26,610 reinforced concrete buildings between 1 to 7 stories in Antalya were examined by using the rapid visual assessment method. A specific threshold value for the city of Antalya was determined with the second level examination and statistical methods carried out in the determined sub-region. With the micro zonation process, regions below the threshold value are defined as the priority areas that need to be examined in detail. The developed methodology can be easily calibrated for application in other cities and can be used to determine new threshold values for those cities.