• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.92-99
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• 2011

Ultra High Performance Concrete(UHPC) is a superior structural material with high strength and durability. Construction of light and slim structures is realized to apply this expectable new materials in practice. This research is a part of the project to develop UHPC precast deck system for hybrid cable stayed bridge. The main object of this study is to investigate behavior of the lap-spliced reinforced connection in UHPC. The major parameter considered in experimental plan was lap-spliced length. The 4-points bending test for 12 specimens were conducted to verify the effect of considered parameters. Test results show that the minimum value of lap spliced length of 300mm which specified in current korea high bridge design code was very conservative for UHPC precast deck system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.138-147
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• 2018

With the recent series of damage caused by earthquakes in Korea, such as Gyeongju and Pohang, we know that Korea is no longer a safe zone for earthquakes and that we need to be prepared for them. In addition, bridges built prior to the introduction of seismic design concepts remain without adequate seismic reinforcement measures, and earthquake reinforcement should be performed efficiently considering economic and structural safety. Preliminary assessment of seismic performance of existing bridges is divided into four seismic groups, taking into account seismicity, vulnerability and Impact, considering the magnitude of the existing bridge's seismic, and prioritization for further evaluation of seismic performance. In this study, unlike the existing anti-seismic reinforcement priority method, scores are calculated based on the seismic design criteria applied to bridges, importance coefficient of the bridge including the zone coefficient and the Importance, vulnerability index of the bridge including the soil condition and the elapsed years, detail coefficient of the bridge including the superstructure form, the span length, the width, the height, the design load, and the daily traffic volume. The calculated score items will be weighted and grouped according to the results. Using this, a simpler and more efficient algorithm was proposed to determine the priority of seismic reinforcement on a bridge.

• Journal of Korean society of Dental Hygiene
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• v.11 no.3
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• pp.313-323
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• 2011

Objectives : The purpose of this study was to examine effect of attribution disposition and self-efficacy on test anxiety in selected college students who major in dental hygiene. This study provides basic data to develop a program for dental hygiene students to reduce test anxiety. Methods : 328 students from A college in Kyungnam, B college in Chunnam and C university in Chungnam who majored in dental hygiene were asked to answer the self-efficacy scale, attribution disposition and test anxiety scale in November and December. 2008. Total of 311 copies were analyzed. Using SPSS 15.0, correlation analysis was conducted and structural model was verified using AMOS 7.0. Evaluation of mediated effect of attribution disposition in suggested structural model was assessed using Sobel verification. Results : 1. Looking at the correlation among self-efficacy, attribution disposition and test anxiety. Self-efficacy had negative relation with external attribution disposition and test anxiety. External attribution disposition had positive relation with test anxiety. 2. Path coefficient from self-efficacy to internal attribution disposition was significant positively and path coefficient from self-efficacy to external attribution disposition was significant negatively. However, the path coefficient from self-efficacy to test anxiety was insignificant. 3. Path coefficient from external attribution disposition to self-efficacy was positively significant. However, the path coefficient from internal attribution disposition to self-efficacy was not significant statistically. 4. In structural model among attribution disposition, test anxiety and self-efficacy, indirect effect of external attribution dispositions was significant statistically. The students with higher self-efficacy showed lower external attribution disposition, the students with lower external attribution disposition showed lower test anxiety. Conclusions : To reduce test anxiety, educators should find a strategy that can improve students' self-efficacy and change their attribution disposition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.3
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• pp.205-213
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• 2003

The primary purpose of this study is to investigate punching shear capacity of flat plate slab using high strength concrete in column. It may be much contributed to economy efficiency and structural advantages that High Strength Concrete(HSC) used for vertical member and Normal Strength Concrete(NSC) for horizontal member. Therefore, six plate flat slab specimens with HSC column and NSC slab had been made and tested with real scale. The major variables were compressive strength of concrete(fck=285, $460kgf/cm^2$), extended length of HSC from column face and amount of shear reinforcements. As the result of this test, the maximum load and punching shear capacity of specimens is affected by extended length and shear reinforcements.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.67-74
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• 2015

RC (Reinforced Concrete) structures are considered as cost-benefit and durable however performances of structural safety and durability are degraded due to steel corrosion. Service life in RC structure is differently evaluated due to different local environmental conditions even if it is exposed to the same chloride attack. In the paper, 25 concrete cores from field investigation are obtained from 4 RC columns with duration of 3.5~4.5 years exposed to sea water. Through total chloride content measurement, surface chloride contents and apparent diffusion coefficients are evaluated. Service life of the target structure is estimated through deterministic method based on Fick's $2^{nd}$ Law and probabilistic method based on durability failure probability, respectively. Probability method is evaluated to be more conservative and relatively decreased service life is evaluated in tidal zone and splash zone over 40.0 m. Chloride penetration behavior with coring location from sea level and the present limitations of durability design method are investigated in the paper.

• Journal of the Korean Institute of Gas
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• v.24 no.4
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• pp.10-17
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• 2020

The structural reliability assessment can be used to improve the reliability in the asset integrity management of the pipeline by using a geometric variation, mechanical characteristics, load change and operating condition as evaluation factors. When evaluating structural reliability, the failure probability of the natural gas pipe is evaluated by the relationship of the resistance of the pipe material to external loads. The failure probability of the natural gas pipe due to the combined stresses such as the internal pressure, thermal stress and bending stress was evaluated by using COMREL program. When evaluating the failure probability of the natural gas pipe, a buried depth of 1.5 to 30 m, a wheel load of 2.5 to 20 ton, a temperature difference of 45℃, an operating pressure of 6.86MPa, and a soil density of 1.8 kN/㎥ were used. The failure probabilities of the natural gas pipe were evaluated by the Von-Mises stress criterion as the maximum allowable stress criterion under the combined stresses.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.83-90
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• 2016

PURPOSES : Nowadays, cavity phenomena occur increasingly in pavement layers of downtown areas. This leads to an increment in the number of potholes, sinkholes, and other failure on the road. A loss of earth and sand from the pavement plays a key role in the occurrence of cavities, and, hence, a structural-performance evaluation of the pavement is essential. METHODS: The structural performance was evaluated via finite-element analysis using KPRP and KICTPAVE. KPRP was developed in order to formulate a Korean pavement design guide, which is based on a mechanical-empirical pavement design guide (M-EPDG). RESULTS: Installation of the anti-freezing layer yielded a fatigue crack, permanent deformation, and international roughness index (IRI) of 13%, 0.7 cm, and 3.0 m/km, respectively, as determined from the performance analysis conducted via KPRP. These values satisfy the design standards (fatigue crack: 20%, permanent deformation: 1.3 cm, IRI: 3.5 m/km). The results of FEM, using KICTPAVE, are shown in Figures 8~12 and Tables 3~5. CONCLUSIONS: The results of the performance analysis (conducted via KPRP) satisfy the design standards, even if the thickness of the anti-freezing layer is not considered. The corresponding values (i.e., 13%, 0.7 cm, and 3.0 m/km) are obtained for all conditions under which this layer is applied. Furthermore, the stress and strain on the interlayer between the sub-grade and the anti-freezing layer decrease gradually with increasing thickness of the anti-freezing layer. In contrast, the strain on the interlayer between the sub-base and the anti-freezing layer increases gradually with this increase in thickness.

• Journal of Korean Society of Transportation
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• v.33 no.6
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• pp.531-542
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• 2015

The discussion about the structural reformation of Korean rail industry has been consistently conducted from the evaluation on Korean National Railroad's management in 1998, the foundation of KORAIL in 2005 to the approval of Suseo KTX corporation establishment in 2013 and the controversy over its privatization. This research explores the changes of government policies by applying to ACF in the assumption that those changes have been implemented due to the interaction of various external variables and main agents in policy which had existed for a long-term period that the rail industry's structural reformation has been practiced for more than 10 years. The unions failed to reach an agreement for the rail industry's structural reformation, the policies regarding the reformation have been led by superior political unions. And this research concludes that a mediator who can compromise unions' different policy preferences and means and bring up a compromised decision in conflicted situation plays a pivotal role to successfully practice these policies.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.1
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• pp.45-52
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• 2016

Blast furnaces are crucial equipment for steel production. A typical furnace risks unexpected accidents caused by contraction and expansion of the walls under an environment of high temperature and pressure. In this study, an acoustic emission (AE) monitoring system was tested for evaluating the large-scale structural health of a blast furnace. Based on the growth of shell cracks with the emission of high energy levels, severe damage can be detected by monitoring increases in the AE energy parameter. Using this monitoring system, steel mill operators can establish a maintenance period, in which actual shell cracks can be verified by cross-checking the UT. From this study, we expect that AE systems permit early fault detection for structural health monitoring by establishing evaluation criteria based on the severity of shell cracking.

• Journal of Korea Multimedia Society
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• v.16 no.3
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• pp.388-398
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• 2013

The purpose of this study is to examine that the effects of social philanthropy initiatives the firm's image of corporate social responsibility. The present study analyzed the structural relationship between three motivations of social philanthropy and evaluation of firm, using structural equation modeling as the method of analysis of the data which were collected from surveying 310 random individuals at galleries and performance halls across the nation. The current study found that the focus on customer value positively influenced the firm image, while motivation for enterprise value had a negative effects on the firm image. This study conducted the test of the structural model invariance across the groups. This study also found that the correlation of motivation for customer to the firm image was much stronger in CSV group than its counterpart. In contrast, the correlation of focus on firm enterprise value to the firm image was much stronger in CSR group than CSV.