• Title/Summary/Keyword: damage behavior

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Revision of Repair Materials Performance Requirement for Concrete Structures (콘크리트 구조물 단면복구공사 보수재료 품질기준개선)

  • Lee, Il Keun;Kim, Ki Hwan;Kim, Hong Sam;Yun, Sung Hwan;Kim, Woo Seok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.43 no.1
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    • pp.9-20
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    • 2023
  • For highway concrete structures, the deterioration of the structure is accelerated due to the increase in the use of deicing materials, and sectional repair work is being frequently carried out to restore performance. However, after the repair work, re-damage such as cracks, delamination, and poor bond performance is exhibited in the repaired sectional area. In this study, overseas repair material requirements were first analyzed, and present domestic requirements were improved repair material performance through field surveys of common concrete structures, laboratory experiments, and test construction on a disused concrete bridge. In addition, performancebased quality requirements were presented so that all materials that meet the required performance can be applied, and different test methods for each material were unified into concrete test methods for consistent test results analysis. The considered performance requirements were compression strength, bending strength, and bond strength for structural properties, and length change rate, crack resistance, thermal expansion coefficient, and elasticity coefficient were for dimensional behavior. For resistance to chloride penetration resistance and freeze-thaw resistance were presented as durability. The proposed requirements for concrete repair materials are expected to contribute to the improvement of the quality of concrete sectional repair work in Korea.

Rainfall Forecasting Using Satellite Information and Integrated Flood Runoff and Inundation Analysis (I): Theory and Development of Model (위성정보에 의한 강우예측과 홍수유출 및 범람 연계 해석 (I): 이론 및 모형의 개발)

  • Choi, Hyuk Joon;Han, Kun Yeun;Kim, Gwangseob
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.6B
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    • pp.597-603
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    • 2006
  • The purpose of this study is to improve the short term rainfall forecast skill using neural network model that can deal with the non-linear behavior between satellite data and ground observation, and minimize the flood damage. To overcome the geographical limitation of Korean peninsula and get the long forecast lead time of 3 to 6 hour, the developed rainfall forecast model took satellite imageries and wide range AWS data. The architecture of neural network model is a multi-layer neural network which consists of one input layer, one hidden layer, and one output layer. Neural network is trained using a momentum back propagation algorithm. Flood was estimated using rainfall forecasts. We developed a dynamic flood inundation model which is associated with 1-dimensional flood routing model. Therefore the model can forecast flood aspect in a protected lowland by levee failure of river. In the case of multiple levee breaks at main stream and tributaries, the developed flood inundation model can estimate flood level in a river and inundation level and area in a protected lowland simultaneously.

Tunnel Design/Construction Risk Assessment base on GIS-ANN (GIS-ANN 기반의 도심지 터널 설계/시공 위험도 평가)

  • Yoo, Chung Sik;Kim, Joo Mi;Kim, Sun Bin;Jung, Hye Young
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1C
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    • pp.63-72
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    • 2006
  • Due to rapid development of many cities in Korea, many public facilities are required to be built as well as complementary civil structures. Consequently, a number of tunnel constructions are currently carried out throughout the country, and many more tunnels are planned to be constructed in the near future. Tunnel excavation in a city often causes serious damage to above-ground structures and sewer system because of unexpected settlement. In order to prevent the destruction, the tunnel, which bypasses the center of a city, must be specially evaluated for its influence to other structure. In addition, since a slight disturbance of above-ground structure causes numerous public complaints and civil appeals, it must be approached with different method than the mountain tunnels. In this paper, the evaluation method using the Artificial Neural Network (ANN) has been studied. The method begins with an analysis of the minimal sectional area. If its result can be used to approximate the general influence of the whole section, the actual evaluation using ANN will take off. In addition, it also studies the construction management method which reflects the real time soil behavior and environment influence during construction using Geographic Information System (GIS).

Stress analysis of high-temperature superconducting wire under electrical/magnetic/bending loads

  • Dongjin Seo;Yunjo Jung;Hong-Gun Kim;Hyung-Seop Shin;Young-Soon Kim
    • Progress in Superconductivity and Cryogenics
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    • v.25 no.4
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    • pp.19-23
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    • 2023
  • The Second-generation high-temperature superconducting (HTS) Rare-Earth Barium Copper Oxide (REBCO) wire is a composite laminate having a multi-layer structure (8 or more layers). HTS wires will undergo multiple loads including the bending-tension loads during winding, high current density, and high magnetic fields. In particular, the wires are subjected to bending stress and magnetic field stress because HTS wires are wound around a circular bobbin when making a high-field magnetic. Each of the different laminated wires inevitably exhibits damage and fracture behavior of wire due to stress deformation, mismatches in thermal, physical, electrical, and magnetic properties. Therefore, when manufacturing high-field magnets and other applications, it is necessary to calculate the stress-strain experienced by high-temperature superconducting wire to present stable operating conditions in the product's use environment. In this study, the finite element model (FEM) was used to simulate the strain-stress characteristics of the HTS wire under high current density and magnetic field, and bending loads. In addition, the result of obtaining the neutral axis of the wire and the simulation result was compared with the theoretical calculation value and reviewed. As a result of the simulation using COMSOL Multiphysics, when a current of 100 A was applied to the wire, the current value showed the difference of 10-9. The stress received by the wire was 501.9 MPa, which showed a theoretically calculated value of 500 MPa and difference of 0.38% between simulation and theoretical method. In addition, the displacement resulted is 30.0012 ㎛, which is very similar to the theoretically calculated value of 30 ㎛. Later, the amount of bending stress by the circular mandrel was received for each layer and the difference with the theoretically obtained the neutral axis result was compared and reviewed. This result will be used as basic data for manufacturing high-field magnets because it can be expanded and analyzed even in the case of wire with magnetic flux pinning.

The Rehabilitation of Gambling Addiction: Comparison with the other psychiatric disorder (도박중독의 재활: 타 정신장애와의 비교)

  • Heung-Pyo Lee;Tae-Woo Kim
    • Korean Journal of Culture and Social Issue
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    • v.16 no.3
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    • pp.241-265
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    • 2010
  • This study reviewed the present state and differences of rehabilitation programs of the gambling addiction by comparing with other psychiatric disorder(including psychotic disability and alcohol addiction). This study also intended to suggest necessities, meanings and inherent fields of the rehabilitation in gambling addiction. First of all, the government and a few gambling industries run clinic centers for gamblers and their families, but have been lacked rehabilitation services for social comeback and adaptation or devaluated rehabilitation services than therapies. Gambling addict didn't have impairments of the cognitive function and their daily abilities was better than any other psychiatric disorders. But Damage of social role or function of gambling addiction was severe. And it is caused by nonadaptive nature of gambling behavior, personality/emotional change through gambling addiction process, and previous personality problem etc. There are many severe failure of social role and its attendant bankrupcy, family's problems and social poverty in gambling addiction, Therefore, important fields in the rehabilitation of gambling addiction should be services for basic social comeback support service, credit recovery support, monetary management, support of rehabilitation of family and vocational rehabilitation. Finally, the significance and critical points of the current study has been discussed as well.

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Analysis of Applicability of Rapid Hardening Composite Mat to Railway Sites (초속경 복합매트의 철도현장 적용성 분석)

  • Jang, Seong Min;Yoo, Hyun Sang;Oh, Dong Wook;Batchimeg, Banzragchgarav;Jung, Hyuk Sang
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.44 no.1
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    • pp.109-116
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    • 2024
  • The Rapid Hardening Composite Mat (RHCM) is a product that improves the initial strength development speed of conventional Geosynthetic Cementitious Composite Mats (GCCM). It offers the advantage of quickly securing sufficient strength in railway slopes with insufficient formation level, and provides benefits such as preventing slope erosion and inhibiting vegetation growth. In this study, an analysis of the practical applicability of RHCM in railway settings was conducted through experimentation. The on-site applicability was assessed by categorizing it into fire resistance, durability, and stability, and conducting combustibility test, ground contact pressure test, and daily displacement analyses. In the case of South Korea, where a significant portion of the territory is composed of forested areas, the prevention of slope fires is imperative. To analyze the fire resistance of RHCM, combustibility tests were conducted as an essential measure. Durability was assessed through ground contact pressure tests to analyze the deformation and potential damage of RHCM caused by the inevitable use of small to medium-sized equipment on the construction surface. Furthermore, daily displacement analysis was conducted to evaluate the structural stability by comparing and analyzing the displacement and behavior occurring during the application of RHCM with railway slope maintenance criteria. As a result of the experiments, the RHCM was analyzed to meet the criteria for heat release rate and gas toxicity. Furthermore, the ground contact pressure was observed to be consistently above 50 kPa during the curing period of 4 to 24 hours under all conditions. Additionally, the daily displacement analyzed through field site experiments ranged from -1.7 mm to 1.01 mm, confirming compliance with the criteria.

How Vulnerability Research Motives Influence the Intention to Use the Vulnerability Market? (취약점 연구동기가 취약점마켓 이용의도에 어떠한 영향을 미치는가?)

  • Hyeong-Yeol Kim;Tae-Sung Kim
    • Information Systems Review
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    • v.19 no.3
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    • pp.201-228
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    • 2017
  • Vulnerability information, which can cause serious damage to information assets, has become a valuable commodity, thereby leading to the creation of a vulnerability market. Vulnerability information is traded on the vulnerability market from several hundred dollars to hundreds of thousands of dollars depending on its severity and importance, and the types and scope of the vulnerability markets are varying. Based on previous studies on vulnerability markets and hackers, this study empirically analyzed the effects of the security researcher's vulnerability research motivation on his/her vulnerability market use intention. The results are discussed as follows. First, vulnerability research self-efficacy had a significant effect on flow and on white and black market use intention but not on perceived benefit. Second, flow had a significant effect on perceived benefit and on black market use intention but had no effect on white market use intention. Third, perceived profit had a significant effect on white and black market use intention. Fourth, vulnerability research self-efficacy had a significant effect on perceived benefit through flow. Fifth, flow had a significant effect on white and black market use intention through perceived profit. These findings can be used to predict the behavior of security researchers who have experience in exploiting vulnerabilities.

Method to Derive the Optimal Vent Position when Flammable Liquid Leaks Based on CFD (CFD 기반 인화성 액체 누출 시 최적의 환기구 배치 도출 방안)

  • Eun-Hee Kim;Seung-Hyo An;Jun-Seo Lee;Byung-Chol Ma
    • Journal of the Korean Institute of Gas
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    • v.28 no.1
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    • pp.11-18
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    • 2024
  • If flammable liquid leaks, vapor evaporated from the pool can cause poisoning or suffocation to workers, leading to secondary accidents such as fires and explosions. To prevent such damage, ventilation facilities shall be installed when designing indoor workplaces. At this time, the behavior varies depending on the characteristics of the leaked chemical, so it is necessary to select a suitable vent location according to the material. Therefore, 3D CFD simulations were introduced to derive optimal vent position and ventilation efficiency was quantitatively evaluated by vent position. At this time, assuming a situation in which flammable liquids leak at indoor workplaces to form pools, the concentration of vapor evaporated from pools was compared to derive the optimal vent position. As a result of research on toluene with high vapor density, ventilation efficiency was confirmed to be the highest at the upper supply-lower exhaust, and it is judged that introducing it can achieve about 3.7 times ventilation effect at the same maintenance cost. Through this study, it is expected that the workplace will be able to secure workers' safety by applying simulation results and installing ventilation ports.

Limit State Evaluation of Elbow Components Connected with Flexible Groove Joints (유동식 그루브 조인트로 연결된 엘보 요소의 한계상태 평가)

  • Sung-Wan Kim;Da-Woon Yun;Bub-Gyu Jeon;Dong-Uk Park;Sung-Jin Chang
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.28 no.3
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    • pp.91-99
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    • 2024
  • Piping systems are crucial facilities used in various industries, particularly in areas related to daily life and safety. Piping systems are fixed to the main structures of buildings and facilities but do not support external loads and serve as non-structural elements performing specific functions. Piping systems are affected by relative displacements owing to phase differences arising from different behaviors between two support points under seismic loads; this can cause damage owing to the displacement-dominant cyclic behavior. Fittings and joints in piping systems are representative elements that are vulnerable to seismic loads. To evaluate the seismic performance and limit states of fittings and joints in piping systems, a high-stroke actuator is required to simulate relative displacements. However, this is challenging because only few facilities can conduct these experiments. Therefore, element-level experiments are required to evaluate the seismic performance and limit states of piping systems connected by fittings and joints. This study proposed a method to evaluate the seismic performance of an elbow specimen that includes fittings and joints that are vulnerable to seismic loads in vertical piping systems. The elbow specimen was created by connecting straight pipes to both ends of a 90° pipe elbow using flexible groove joints. The seismic performance of the elbow specimen was evaluated using a cyclic loading protocol based on deformation angles. To determine the margin of the evaluated seismic performance, the limit states were assessed by applying cyclic loading with a constant amplitude.

Effects of Patriotism on Product Evaluation: Focused on the Mediating Effects of Consumer Ethnocentrism (애국심이 제품평가에 미치는 영향: 소비자 자민족중심주의의 매개효과를 중심으로)

  • Hong, Sung-Tai;Kang, Dong-Kyoon
    • Journal of Distribution Research
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    • v.15 no.2
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    • pp.71-99
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    • 2010
  • Most of studies on patriotism in the marketing area have focused on ethnocentric tendencies observed in consumption behaviors. On the contrary, there have been few empirical studies on how patriotism in the general sense, indicating affection for, attachment to, and pride in the country, influences consumers' evaluation of domestic and foreign products. Given the current situation that marketing activities appealing to people's patriotism is increasing, this is somewhat surprising. Thus, this study examined empirically how patriotism influences people's evaluation of domestic and foreign products. In addition, we tested whether consumer ethnocentrism works as an intervening variable in the relation between patriotism and product evaluation. The empirical analysis was conducted through a questionnaire survey of undergraduate and graduate students at universities in Seoul. The survey asked about the respondents' patriotism, consumer ethnocentrism, domestic product evaluation, foreign product evaluation, and demographical characteristics. In foreign product evaluation, the respondents were requested to evaluate Chinese and Japanese products. Email was used to send and recover the questionnaires, and 135 replies were used in the analysis. Major findings from the empirical analysis are as follows. First, a significant relationship was observed between patriotism and domestic product evaluation. That is, patriotic participants evaluated domestic products more favorably. On the other hand, no significant relationship was observed between patriotism and foreign product evaluation(See Table 1-1 and 1-2). Next, the effect of patriotism on domestic product evaluation was mediated by consumer ethnocentrism. However, whether the effect of patriotism on domestic product evaluation is mediated by consumer ethnocentrism partially or fully was different according to product(See Table 2-1 and 2-2). Lastly, we tried to analyze the relation between consumer ethnocentrism and product evaluation and comparing the results with findings of previous researches. According to the results, a significant relationship was observed between consumer ethnocentrism and domestic product evaluation but not between consumer ethnocentrism and foreign product evaluation. The meanings of this study are as follows. First, there have been few marketing studies that investigated the relation between patriotism and product evaluation. Thus, this study is meaningful in that it supplemented the limitation of previous research. Second, consumer ethnocentrism was found to mediate the relation between patriotism and domestic product evaluation. Considering the absence of previous research that examined the role of consumer ethnocentrism as an intervening variable, this study is significant in that it expanded the scope of research on consumer ethnocentrism. Third, from the practical aspect, the results of this study suggest that marketing appealing to patriotism is effective in stimulating consumers' purchase and consumption of domestic products. Accordingly, such a marketing strategy is expected to be effective in protecting domestic markets from imported goods and overseas brands and to increase demands for domestic products and brands. However, there is the question of whether the effect of patriotism based marketing strategies in promoting demand for domestic products would persist. That is, this study could not find a significant relation between patriotism and foreign product evaluation, and this means that the increase in patriotism for the home country does not damage people's view to the quality of foreign products negatively. Accordingly, without change in people's perception of foreign products, it is highly likely that the increase in demand for domestic products or brands induced by patriotism elevated at a specific time or situation may not last long. Fourth, the results of this study suggest that the patriotism level may influence consumers' choice behavior toward retailers strongly connected to a specific country or region. That is, consumers with high level patriotism may hesitate or avoid using a retailer associated with some foreign country. Fifth, according to the results of this study, when people's patriotism is stimulated by a specific social situation or event, it can be an opportunity for domestic franchise brands to increase their market performance such as sales and market share and, at the same time, for foreign franchise brands to experience adversities. Therefore, during a period like the Olympic Games or the World Cup when people's sense of belonging or attachment to their country is heightened, domestic franchise brands need to make marketing activities that may lead market opportunities to substantial results and foreign franchise brands to cope with such adversities. Sixth, consumers' brand choice is often made in retail stores. It has been demonstrated by numerous studies that in store stimuli such as point of purchase display can affect consumers' behavior. Considering this, domestic brands facing competition with foreign brands should make continuous efforts to enhance the market performance of their products through developing in store stimuli that can stimulate consumers' patriotism. Finally, based on the major findings of this study, both academic and practical issues were discussed. Suggestions for future studies were provided.

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