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A Study on the Method of Resistance Analysis of Water Stream During Fire Supperession (화재진압 시 발생하는 주수 기둥의 저항분석 방법 연구)

  • Jung, Byeong-Sun;Kim, Eung-Sik;Park, Jong-Yeol
    • Journal of the Korean Society of Safety
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    • v.33 no.6
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    • pp.22-27
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    • 2018
  • Fire fighters are exposed to the risk of many accidents during fire suppression, especially near the high voltage circuit. In order to prevent and analyze the electric shock accidents, measurement of water resistance is crucial. However, this has been one of the overlooked research areas and it has been very difficult to measure the mixed up resistance components separately. In this paper, we measured a total resistance of apparatus and regarded it as a serial resistance of contact resistance and length dependant resistance. Measuring the resistance by varying the length of water stream, the variable resistance and fixed contact resistance appear, which are used to calculate the both components of resistances. In addition, the resistance of fire hose can be calculated from the parallel circuit which is formed by grounding the fire hose with the resistance of water stream. Results show that we can successfully measure the resistance per unit length of water stream and fire hose, thereby proving that this method is a facile way to measure water and fire hose resistance. However, many experiments are still required to obtain the precise contact resistance of ground under various condition and the resistance between the human body and fire hose.

A Study on the Resistance Factors for Mobile Easy Remittance Service Acceptance - Based on the Switching Cost and Innovation Resistance Model (모바일 간편송금서비스 수용에 대한 저항요인 연구 : 전환비용과 혁신저항모형을 중심으로)

  • Jeong, Seok Chan;Jeon, Hwa Mok
    • The Journal of Information Systems
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    • v.28 no.3
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    • pp.59-81
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    • 2019
  • Purpose The purpose of this study is to investigate the resistance factors interfering the acceptance factors of the mobile easy remittance service focusing on the switching cost and the innovation resistance model. Design/methodology/approach This study focuses on revealing the resistance factors of the mobile easy remittance service acceptance. The resistance factor is designed consisting both consumer characteristics and service characteristics in the Innovation Resistance Model. Furthermore, the effect of resistance factors on the innovation resistance and acceptance intentions were detected by moderating the switching cost. Findings According to the empirical analysis result, this study investigated the effect of resistance factors on innovation resistance and acceptance intention for the mobile easy remittance service. The results of this study as follows; (1) The consumer's inherent innovativeness did not significantly affect the innovation resistance and acceptance intention. (2) The attitude toward existing services and complexity significantly affected innovation resistance in direct manner, thus affecting the acceptance intention in indirect manner. (3) The perceived usefulness significantly affected both the innovation resistance and the acceptance intention in direct manner. (4) The perceived risk only effected the acceptance intention. (5) The switching cost had a moderating effect on the innovation resistance and acceptance intention.

Shear resistance characteristic and ductility of Y-type perfobond rib shear connector

  • Kim, Sang-Hyo;Park, Se-Jun;Heo, Won-Ho;Jung, Chi-Young
    • Steel and Composite Structures
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    • v.18 no.2
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    • pp.497-517
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    • 2015
  • This study evaluates behavior of the Y-type perfobond rib shear connector proposed by Kim et al. (2013). In addition, an empirical shear resistance formula is developed based on push-out tests. Various types of the proposed Y-type perfobond rib shear connectors are examined to evaluate the effects of design variables such as concrete strength, number of transverse rebars, and thickness of rib. It is verified that higher concrete strength increases shear resistance but decreases ductility. Placing transverse rebars significantly increases both the shear resistance and ductility. As the thickness of the ribs increases, the shear resistance increases but the ductility decreases. The experimental results indicate that a Y-type perfobond rib shear connector has higher shear resistance and ductility than the conventional stud shear connector. The effects of the end bearing resistance, resistance by transverse rebars, concrete dowel resistance by holes, and concrete dowel resistance by Y-shape ribs on the shear resistance are estimated empirically based on the push-out test results and the additional push-out test results by Kim et al. (2013). An empirical shear resistance formula is suggested to estimate the shear resistance of a Y-type perfobond shear connector for design purposes. The newly developed shear resistance formula is in reasonable agreement with the experimental results because the average ratio of measured shear resistance to estimated shear resistance is 1.024.

Effects of Resistance and Resistance & Stabilization Exercises on the Strength of Lumbar and Lower Limbs of the Elderly

  • Choi, Seok Joo;Kim, Jong Woo;Hwang, Byeong Jun
    • Journal of International Academy of Physical Therapy Research
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    • v.4 no.2
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    • pp.611-617
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    • 2013
  • The purpose of this study is to identify the effective lumbar area exercise program to prevent falls of the elderly by dividing 14 female elders over 65 living in Daegu into two groups such as resistance exercise group and resistance & stabilization exercise group, and applying a 60 minute exercise program three times a week for 12 weeks. The followings are the results. First, both of resistance exercise and resistance & stabilization exercise brought improvement of lumbar strength and there was no significant difference between two groups. Second, there was no significant difference in lower limb strength in resistance exercise group but resistance & stabilization exercise group showed significant increase in lower limb flexor strength. To make a summary of the above results, it can be said that 12 weeks' resistance & stabilization exercise is effective to the lumbar strength and lower limb strength of the elderly. Accordingly, if combining resistance exercise and stabilization exercise appropriately, we can build a successful preventive program which even the elderly who cannot perform resistance exercise easily can follow.

Evaluation of the Fire Resistance Performance of Interior Anchor Type CFT Columns through Loaded Heating Test

  • Kim, Sunhee;Yom, Kyongsoo;Choi, Sungmo
    • International Journal of High-Rise Buildings
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    • v.2 no.1
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    • pp.39-48
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    • 2013
  • The fire resistance performance of generic CFT columns has been verified through various tests and analyses and the columns are widely used for fire resistance designs abroad. In this study, 3 groups of specimens (Non-fire protection, reinforcement with steel fiber and fire resistance paint) are suggested in order to evaluate the fire resistance performance of interior anchor type concrete-filled steel tubular columns having efficient cross-sections through loaded heating tests. Axial deformation-time relationship and in-plane temperatures are compared to evaluate the fire resistance performance of the specimens associated with variables. Suggested from the fact that the interior anchors exposed to fire exert influence on fire resistance performance due to thermal expansion, the reinforcements using steel fiber and fire resistance paint are verified to mitigate contraction and improve fire resistance performance. The result obtained from the tests of interior anchor type concrete-filled tubular columns is expected to be used for effective fire resistance design in association with previously conducted studies.

Strategy for Insecticide Resistance Management Approach to IPM

  • Motoyama, Naoki;Dauterman, W.C.
    • Korean journal of applied entomology
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    • v.31 no.3
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    • pp.314-327
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    • 1992
  • Insecticide resistance is a serious is a serious threat to IPM, resulting in various adverse effects not to mention the loss of yield in agriculture. One approach to counter the problem is the disruption of resistance mechanisms. This can be achieved by (1) compounds which show a negative correlation with resistance at the site of action, (2) specific metabolic inhibitors which serve as synergists, or (3) a certain combination of two insecticides producing a joint action. This approach, however, requires certain precautions for the side effects may cause an increase in toxicity to mammals. Owing to the recent advances in theoretical studies on resistance management employing computer simulation and mathematical models, a few principles to reduce the risk of development of resistance have been clarified. They are helpful in designing operational strategies with regard to, for instance, insecticide doses to be applied, mode of application, and choice and nature of the insecticide(s) to be used. For restoration of insecticide susceptibility of a resistant population, reintroduction of susceptible individuals to the resistant population is feasible when certain conditions are met. Natural enemies which developed resistance to insecticides can be an important component of IPM as has been shown in the pest management in apple orchards. After all, the implementation of a successful resistance management program depends upon cooperation between different sigments of the agricutural community. Although resistance is a preadaptive phenomenon, in some cases spontaneous loss of resistance does occur without contamination by susceptible individuals. The instability of resistance in these insects implies the possible existence of a switch machanism controlling the expression of resistance gene(s). Elucidation of such a mechanism may eventually provide us with a new technical approach with which we can combat the problem of insecticide resistance.

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The High Resistance Measurement up to 100 PΩ using a Low Resistance, a Low Voltage Source and a Commercial Digital Multimeter

  • Yu, Kwang Min;Lee, Sang Hwa;Kang, Jeon Hong;Kim, Wan-Seop
    • Journal of Electrical Engineering and Technology
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    • v.13 no.3
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    • pp.1392-1397
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    • 2018
  • The potentiometric measurement result for a high resistance up to $100P{\Omega}$ using a low resistance, a low voltage source and a commercial digital multimeter(DMM) is presented. With the method, a resistance can be easily, fast and economically measured. Using the method, resistance ranges over the $10G{\Omega}$ range which is difficult to measure using a commercial DMM and resistance ranges between $100T{\Omega}$ and $100P{\Omega}$ which cannot measure using an insulation tester were measured within accuracy of a few percent. It is expected that it can be useful to determine the temperature and voltage effect of a high resistance and an insulation material because it uses a reference resistance with a low resistance, very low temperature and voltage effect. Besides, it is expected that it can be useful to calibrate a dc high voltage divider with a large resistance ratio and a very low resistance because arbitrary resistance ratio measurements are possible with it.

Characteristics of Matrix Retaining Electrolyte in a Phosphoric Acid Fuel Cell Analyzed by A.C. Impedance Spectroscopy (복소임피던스법에 의한 인산형 연료전지용 전해질 매트릭스 특성)

  • 윤기현;장재혁;허재호;김창수;김태희
    • Journal of the Korean Ceramic Society
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    • v.32 no.2
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    • pp.189-196
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    • 1995
  • Materials retaining electrolyte of a phosphoric acid fuel cell (PAFC) have been prepared with SiC powder to SiC whisker mixing ratios of 1:1, 1:2, 1:3, 1:4, 0:1 by a tape casting method. When 3wt% dispersant (sorbitan monooleate) is added to a matrix, the porosity of the matrix decreases a little while the bubble pressure and area of the matrix increase remarkably in comparison with no dispersant content. Effect of the electrolyte resistance and the polarization resistance on perfomance of a PAFC has been investigated using A.C. impedance spectroscopy. With the increase of whisker content, the electrolyte resistance decreases due to the increase of porosity and acid absorbancy, and the polarization resistance increases due to the increase of surface roughness. The polarization resistance affects current density predominantly at the higher potential than 0.7V becuase the polarization resistance is considrably larger than the electrolyte resistance. Both the electrolyte resistance and the polarization resistance affect current density near 0.7V of the fuel cell operating potential because they have similar values. The electrolyte resistance affects current density predominantly at the lower potential than the fuel cell operating potential because the electrolyte resistance is larger than the polarization resistance.

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Mechanisms of herbicide resistance in weeds

  • Bo, Aung Bo;Won, Ok Jae;Sin, Hun Tak;Lee, Jeung Joo;Park, Kee Woong
    • Korean Journal of Agricultural Science
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    • v.44 no.1
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    • pp.1-15
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    • 2017
  • In major field crops, synthetic herbicides have been used to control weeds worldwide. Globally, herbicide resistance in weeds should be minimized because it is a major limiting factor for food security. Cross resistance can occur with herbicides within the same or in different herbicide families and with the same or different sites of action. Multiple resistance refers to evolved mechanisms of resistance to more than one herbicide (e.g., resistance to both ALS-inhibitors and ACCase-inhibitors) and this resistance was brought about by separate selection processes. Target site resistance could occur from changes at the biochemical site of action of one herbicide. Non target site resistance occurs through mechanisms which reduce the number of herbicide molecules that reach the herbicide target site. There are currently 480 unique cases (species ${\times}$ site of action) of herbicide resistance globally in 252 plant species (145 dicots and 105 monocots). To date, resistance in weeds has been reported to 161 different herbicides, involving 23 of the 26 known herbicide sites of action. Finally, it can be concluded that we can protect crops associated to herbicide resistant weeds by applications of biochemical, genetic and crop control strategies.

Skid Resistance of the Sidewalks in Winter (겨울철 보도 미끄럼 저항)

  • Kim, Yong Seok
    • International Journal of Highway Engineering
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    • v.15 no.6
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    • pp.17-23
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    • 2013
  • PURPOSES : This study aimed to measure the skid resistance of the sidewalk in order to find out the relationship between different surface types and skid resistance. By using British Pendulum Tester, skid resistance of sidewalk was measured in a wet after snow-melt, sludgy, and snowy conditions. METHODS : The skid resistance was measured on surfaces including Concrete Interlocking Block Paving, Colour Asphalt Pavement, Granite Block Paving, Manhole, and Tactile Paving for Visually Impaired. Five trials at each measurement were made, and the average and standard deviation were derived. RESULTS : The skid resistance measured in wet after snow-melt, sludgy, and snowy conditions for the various surface types are summarized and compared. Reduction rates of skid resistance of sludgy and snowy against wet after snow-melt are also analysed. The skid resistance variation between measurement points which mimic pedestrian route in study site are analysed to check out the consistency of the skid resistance along the sidewalk. CONCLUSIONS : The study concluded that the skid resistance of sidewalk surfaces varied depending on the surface types and weather conditions. Secondly, reduction rates of skid resistance according to weather changes are varied depending on the surface types, Thirdly, consistency of skid resistance along the pedestrian route is hardly acquired in the study site at least. So, future study on the consistency evaluation for skid resistance along sidewalk is strongly recommended.