• Proceedings of the KOR-KST Conference
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• 1997.12b
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• pp.35-72
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• 1997

This study was conducted to develop a methodology to predict utility pole accident rates and to evaluate cost-effectiveness for safety improvement for utility pole accidents. The utility pole accident rate prediction model was based on the encroachment rate approach introduced in the Transportation Research Board special Report 214. The utility pole accident rate on a section of highway depends on the roadside encroachment rate and the lateral extent of encroachment. The encroachment rate is influenced by the horizontal and vertical alignment of the highway as well as traffic volume and mean speed. The lateral extent of encroachment is affected by the horizontal and vertical alignment, the mean speed and the roadside slope. An analytical method to generate the probability distribution function for the lateral extent of encroachment was developed for six kinds of encroachment types by the horizontal alignment and encroachment direction. The encroachment rate was calibrated with the information on highway and roadside conditions and the utility pole accident records collected on the sections of 55mph speed limit of the State Trunk Highway 12 in Wisconsin. The encroachment rate on tangent segment was calibrated as a function of traffic volume with the actual average utility pole accident rates by traffic volume strategies. The adjustment factors for horizontal and vertical alignment were when derived by comparing the actual average utility pole accident rates to the estimations from the model calibrated for tangent and level sections. A computerized benefit-cost analysis procedure was then developed as a means of evaluating alternative countermeasures. The program calculates the benefit-cost ratio and the percent of reduction of utility pole accidents resulting from the implementation of a safety improvement. This program can be used to develop safety improvement alternatives for utility pole accidents when a predetermined performance level is specified.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.111-116
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• 2022

The causes of motor burnout include overload, phase loss, restraint, interlayer short circuit, winding ground fault, instantaneous overvoltage, and the rotor contacting the stator, leading to insulation breakdown, leading to breakdown or electrical accidents. Therefore, equipment failure causes not only loss due to cost required for equipment maintenance/repair, but also huge economic loss due to productivity decrease due to process stop because the process itself including the motor is stopped. The current level of technology for diagnosing motor failures uses vibration, heat, and power analysis methods, but there is a limit to analyzing the problems only after a considerable amount of time has passed according to the failure. Therefore, in this paper, a device and algorithm for measuring insulation resistance using DC AMP signal was applied to an industrial motor to solve this problem. And by following the insulation resistance state value, we propose a diagnosis of deterioration and failure of the motor that cannot be solved by the existing method.

• Smart Structures and Systems
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• v.29 no.2
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• pp.267-278
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• 2022

Pre-stressed concrete circular spun piles are widely used in various infrastructure projects around the world and offer an economical deep foundation system with consistent and superior quality compared to cast in-situ and other concrete piles. Conventional methods for measuring the lateral response of piles have been limited to conventional instrumentation, such as electrical based gauges and pressure transducers. The problem with existing technology is that the sensors are not able to assist in recording the lateral stiffness changes of the pile which varies along the length depending on the distribution of the flexural moments and appearance of tensile cracks. This paper describes a full-scale bending test of a 1-m diameter spun pile of 30 m long and instrumented using advanced fibre optic distributed sensor, known as Brillouin Optical Time Domain Analysis (BOTDA). Optical fibre sensors were embedded inside the concrete during the manufacturing stage and attached on the concrete surface in order to measure the pile's full-length flexural behaviour under the prescribed serviceability and ultimate limit state. The relationship between moments-deflections and bending moments-curvatures are examined with respect to the lateral forces. Tensile cracks were measured and compared with the peak strains observed from BOTDA data which corroborated very well. By analysing the moment-curvature response of the pile, the structure can be represented by two bending stiffness parameters, namely the pre-yield (EI) and post-yield (EI_cr), where the cracks reduce the stiffness property by 89%. The pile deflection profile can be attained from optical fibre data through closed-form solutions, which generally matched with the displacements recorded by Linear Voltage Displacement Transducers (LVDTs).

• Journal of the Korean Society of Safety
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• v.38 no.1
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• pp.25-33
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• 2023

In this study, we determined the failure rate and fire status of electric motors widely used in domestic and industrial devices and analyzed the associated fire risks by identifying the electrical and temperature characteristics of electric motors under the normal and restrained operation modes in industrial sites and laboratories. A 2.2kW motor used for driving a conveyor during the vulcanization process in a rubber product manufacturing plant was employed as the study object and was exposed to a high- temperature environment as this motor is widely used in industrial sites. The current amplitude was 4.45-4.50 A during normal operation and 38.2-41.5 A during restrained operation due to the pinching of products and semi-finished products (i.e., 8.5 times higher than that during normal operation). The leakage current amplitude was 0.33 mA during both operation modes. The temperature of the workplace in summer was 42.38℃, indicating a poor environment for the installed motor. In the laboratory, the current and temperature of the coil inside a 3.7kW motor were measured under the restrained operation mode as performing measurements of the coil inside the motor in industrial sites is challenging. The current amplitude during normal operation was 3.5 A, whereas that during restrained operation for 30 s was 51.7-58.6 A, which is 14.8-16.7 times higher than that of normal operation. Moreover, the temperature of the motor coil increased from 22.9℃ to 101℃. Based on the experimental data, we derived the temperature increase formula according to the restrained operation time by performing a regression analysis and verified the time at which the temperature exceeded the stipulated limit for the insulation grade. The findings presented in this paper can be utilized to establish fire-prevention measures and perform safety management of motors of the same type or with a similar capacity.

• Earthquakes and Structures
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• v.22 no.5
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• pp.503-515
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• 2022

This paper presents the development of seismic fragility curves for a precast reinforced concrete bridge instrumented with a structural health monitoring (SHM) system. The bridge is located near an active seismic fault in the Dominican Republic (DR) and provides the only access to several local communities in the aftermath of a potential damaging earthquake; moreover, the sample bridge was designed with outdated building codes and uses structural detailing not adequate for structures in seismic regions. The bridge was instrumented with an SHM system to extract information about its state of structural integrity and estimate its seismic performance. The data obtained from the SHM system is integrated with structural models to develop a set of fragility curves to be used as a quantitative measure of the expected damage; the fragility curves provide an estimate of the probability that the structure will exceed different damage limit states as a function of an earthquake intensity measure. To obtain the fragility curves a digital twin of the bridge is developed combining a computational finite element model and the information extracted from the SHM system. The digital twin is used as a response prediction tool that minimizes modeling uncertainty, significantly improving the predicting capability of the model and the accuracy of the fragility curves. The digital twin was used to perform a nonlinear incremental dynamic analysis (IDA) with selected ground motions that are consistent with the seismic fault and site characteristics. The fragility curves show that for the maximum expected acceleration (with a 2% probability of exceedance in 50 years) the structure has a 62% probability of undergoing extensive damage. This is the first study presenting fragility curves for civil infrastructure in the DR and the proposed methodology can be extended to other structures to support disaster mitigation and post-disaster decision-making strategies.

• The Plant Pathology Journal
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• v.39 no.1
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• pp.39-51
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• 2023

Common bean (Phaseolus vulgaris L.) is one of the most important crops in human food production. The occurrence of diseases, such as white mold, caused by Sclerotinia sclerotiorum can limit the production of this legume. The use of Trichoderma has become an important strategy in the suppression of this disease. The aim of the present study was to evaluate the effect of volatile organic compounds (VOCs) emitted by Trichoderma azevedoi CEN1241 in five different growth periods on the severity of white mold in common bean. The in vitro assays were carried out in double-plate and split-plate, and the in vivo assays, through the exposure of the mycelia of S. sclerotiorum to the VOCs of T. azevedoi CEN1241 and subsequent inoculation in bean plants. Chemical analysis by gas chromatography coupled to mass spectrometry detected 37 VOCs produced by T. azevedoi CEN1241, covering six major chemical classes. The profile of VOCs produced by T. azevedoi CEN1241 varied according to colony age and was shown to be related to the ability of the biocontrol agent to suppress S. sclerotiorum. T. azevedoi CEN1241 VOCs reduced the size of S. sclerotiorum lesions on bean fragments in vitro and reduced disease severity in a greenhouse. This study demonstrated in a more applied way that the mechanism of antibiosis through the production of volatile compounds exerted by Trichoderma can complement other mechanisms, such as parasitism and competition, thus contributing to a better efficiency in the control of white mold in bean plants.

• Journal of the Korea Society for Simulation
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• v.26 no.4
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• pp.23-34
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• 2017

During Khmer Rouge Regime, Cambodian pop music was completely forgotten since 90% of artists were killed. After recovering from war since 1979, the music started to grow again in 1990. However, Cambodian popular music dynamic and flows are observably directed by the multifaceted socioeconomic, political and creative forces. The major problems are the plagiarism and piracy which have been prevailing for years in the industry. Recently, the consciousness of the need to preserve Khmer original songs from both fans and artist have been increased and become a new trend for Cambodia young population. Still, the music quality is in the limit state. To increase the mind-set, the feedbacks and inspiration are needed. The study suggested a music ranking website using sentiment analysis which data were collected from Production Companies Facebook Pages' posts and comments. The study proposed an algorithm which translates from Khmer to English, doing sentiment analysis and generate the ranking. The result showed 80% accuracy of translation and sentiment analysis on the proposed system. The songs that rank high in the system are the songs which are original and fit the occasion in Cambodia. With the proposed ranking algorithm, it would help to increase the competitive advantage of the musical productions as well as to encourage the producers to compose the new songs which fit the particular activities and event.

• Toxicological Research
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• v.21 no.1
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• pp.15-21
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• 2005

There is now a growing concern about the possible toxicity of heavy metals in cosmetics. Heavy metals can be used as cosmetic ingredients or may be present as low level impurities in some of the raw materials. Chromium derivatives are used as pigments in cosmetics. Chromium is essential and toxic trace elements. Chromium may cause skin allergy. However, the regulations related to cosmetic products give no limit values for Chromium. Hexavalent chromium is significantly more toxic than trivalent chromium. Hexavalent chromium may present a carcinogenic risk at high concentrations. Therefore, it is important to consider oxidation state of chromium when analyze chromium. The purpose of this study is to determine the concentrations of water-soluble trivalent and hexavalent chromium in samples of makeup products, and to assess the safety of cosmetics on the basis of animal sensitization tests using guinea pig. The present study of chromium in 48 makeup products of 12 manufacturers provides a basis for assessing safety of makeup products. Water-soluble hexavalent chromium was not detected in any product. Water-soluble trivalent chromium was detected in only 9 eye shadows out of 48 makeup products, and could not be quantified 3 out of 9 eye shadows. The highest level of water-soluble trivalent chromium was about 10 mg/kg in spite of 90,000 mg/kg of total chromium. The results of animal sensitization tests show that 200 mg/kg of trivalent chromium and 5 mg/kg of hexavalent chromium have no harmful effect. No cross-reaction among these metals was found. Accordingly, the concentrations of water-soluble chromium in makeup products seemed to be safe. The overall results indicate that chromium in cosmetics probably have no significant toxicological effects. However, It is necessary to set guidelines on the maximum permissible concentration of water-soluble chromium in cosmetics.

• Journal of the Korean Geotechnical Society
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• v.34 no.3
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• pp.13-27
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• 2018

To study how stable the rubble mound breakwaters are, one can look to the research of wave induced seepage flow through the pores of the rubble mound. Seepage flow is generally generated by the difference between the water level around the breakwater during a typhoon. The existing stability analysis method of the rubble mound is the static analysis which simply considers the force equilibrium taking into account the horizontal force acting on the concrete block induced by a wave (calculated by Goda equation) and the vertical force induced by the weight inclusive of the concrete block, quarry run, filter, and armor layer above the slipping plane. However, this static method does not consider the wave-induced seepage flow in the rubble mound. Such seepage may decrease the stability of the rubble mound. The stability of a rubble mound breakwater under the action of seepage was studied based on the results of CFD software (OpenFOAM) and Limit Equilibrium Method (GeoStudio). The numerical analysis result showed that the seepage flow decreased the stability of the rubble mound breakwaters. The results of the numerical analyses also revealed the stability of the rubble mound was varied with time. Especially, the most critical state happened at the condition of overtopping the concrete block, acting strong uplift pressure raising along side and underneath the concrete block, and generating high pore pressure inside rubble mound due to seepage flow. Therefore, it may be necessary to conduct a dynamic analysis considering the effect of wave-induce seepage flow together with the static analysis.

• Journal of the Korean GEO-environmental Society
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• v.13 no.12
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• pp.91-98
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• 2012

In this paper, the behavior of offshore wind turbine(OWT) foundation which is modeled by using existing design method and FEM is compared. When the same type of foundation is designed under the same sea and ground condition, the behavior characteristics with each model are compared. As a result, the member forces between apparent fixity and distributed spring type foundation which consider the ground stiffness are not different markedly, while fixed-base type foundation shows relatively lower member forces, which results in smaller safety margin. In other words, considering ground stiffness is reasonable because soil-pile interaction affects significantly on the analysis result. A case study with a monopile shows significant errors between p-y and FEM model at the head and tip of the pile. Also, it shows that the errors at the tip with diameter increase of the pile is larger. Thus, considering ground characteristics and engineering judgment are necessary in practice. A comparison of reliability analysis between tripod and monopile type foundation on the same condition shows larger probability of failure in monopile type and it indicates that the safety margin of monopile type can be lower.