• Journal of Korean Society of Steel Construction
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• v.28 no.6
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• pp.403-414
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• 2016

Recently according to the decreasing of steel price and increasing of labor cost the various studies of steel structure and composite structure are proceeding. This study developed the new shape of high depth hybid forming composite beam and performed the bending test to evaluate the bending performance by creating 10 specimens. Bending test result showed that capacity of the beam was increased stably. The ratio of the nominal load to the maximum load($P_u/P_n$) is 1.19 and the deformation capacity(${\delta}_{0.8P_u}/{\delta}_y$) is 3.9~4.5. Also, it is possible to apply the existing evaluation equation(KBC 2009) of composite beam.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.455-465
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• 2006

In this study, the effect of scour was evaluated by regional and geotechnical characteristics and back data were accumulate for the design against scour through the local erosion characteristics evaluation of the Inchon coast. The erosion characteristics for the undisturbed soil samples collected near the main locations at the Incheon 2nd bridge, the Hwangyeong bridge, and a coast road in Songdo, are determined quantitatively through the scour rate tests. On the basic soil properties test, the bed around the Inchon coast chiefly consists of fined grained soils, and the soil samples were classified as silty clay(ML) or clay(CL) under the Unified Soil Classification System. On the scour rate test, the critical shear stress increases when the undrained shear strength increases as of the general trend of fine grained soils, and the average scour rate for the maximum velocity by 100 year flood is 173mm/hr at the Incheon 2nd bridge, 67mm/hr at the Hwangyeong bridge and 10mm/hr at a coast road in Songdo, respectively. Comparing to the scour rate of coarse grained soil, that of the bed around the Inchon coast is turned out to be very low. Therefore, the relative ability of the bed around the Inchon coast to resist erosion is assumed to be very high.

• Journal of KIISE:Software and Applications
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• v.32 no.5
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• pp.438-448
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• 2005

This paper proposes an adaptive tutoring system that provides learning materials dynamically according to the learners' teaming character and ability. Our system, in which a learning phase and a test phase are linked together, supports the personalized instruction-learning by providing the teaming materials by level in the learning phase according to the teaming ability estimated in the test phase. We design and implement a tutoring system consisted of an evaluation component and a learning component. An evaluation component uses a computerized adaptive test(CAT) based on item response theory to evaluate learners' ability while a learning component employs fuzzy level set theory so that teaming contents are provided to learners according to learners' level.

• International Journal of Highway Engineering
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• v.19 no.6
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• pp.129-137
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• 2017

PURPOSES : The purpose of this study is to develop bridge deck concrete materials based on ordinary Portland cement concrete, and to evaluate the applicability of the developed materials through material properties tests. METHODS : For field implementation, raw material (cement, fine aggregate, and coarse aggregate) properties, fresh concrete properties (slump and air content), strength (compressive, flexural and bond strength) gain, and durability (freeze-thaw resistance, scaling resistance, and rapid chloride penetrating resistance) performance were evaluated in the laboratory. RESULTS : For the selected binder content of $410kg/m^3$, W/B = 0.42, and S/a = 0.48, the following material performance results were obtained. Considering the capacity of the deck finisher, a minimum slump of 150 mm was required. At least 6 % of air content was obtained to resist freeze-thaw damage. In terms of strength, 51.28 MPa of compressive strength, 7.41 MPa of flexural strength, and 2.56 MPa of bond strength at 28 days after construction were obtained. A total of 94.9 % of the relative dynamic modulus of elasticity after 300 cycles of freeze-thaw resistance testing and $0.0056kg/m^2$ of weight loss in a scaling resistance test were measured. However, in a chloride ion penetration resistance test, the result of 3,356 Coulomb, which exceeds the threshold value of the standard specification (1000 Coulomb at 56 days) was observed. CONCLUSIONS : Instead of using high-performance modified bridge deck materials such as latex or silica fume, we developed an optimum mix design based on ordinary Portland cement concrete. A test construction was carried out at ramp bridge B (bridge length = 111 m) in Gim Jai City. Immediately after the concrete was poured, the curing compound was applied, and then wet mat curing was applied for 28 days. Considering the fact that cracks did not occur during the monitoring period, the applicability of the developed material is considered to be high.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.99-105
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• 2011

When a certain magnitude earthquake occurs, serious damage for human and properties is a major concern for most of the subway stations which were not applied for earthquake resistant design. Consideration and experimental verification for ground and structural behavior based on soil-structure interaction relation are required to evaluate seismic performance of the subway station as embedded structures. For 1/60 scaled subway station model, centrifuge modeling shaking table test is performed using Kobe and Northridge earthquakes. Compare to displacements and moments of the underground and structure obtained by soil response analysis and response displacement method based on experimental results, this paper shows how to evaluate seismic performance of subway station.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1320-1329
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• 1990

A static performance tester for a torque rod assembly was developed to evaluate the three characteristics of the rod rubber bushing : radial spring characteristic, thrust spring characteristic, and rotational torque characteristic. Among the various schemes considered in the conceptual design stage, the final versatile type was determined to perform three different tests in one machine. The performance testing machine carried out radial spring test, thrust spring test, and torque test of the torque rod assembly. Static performance of the torque rod assembly was evaluated with the tester developed and fatigue strength of the assembly was also tested with the servo-hydraulic structural fatigue testing machine. The life of the component was found to be related with the rubber quality and adhesionability between the rubber and the steel rod. The optimum rubber hardness was experimentally found by changing the chemical compositions of rubber, and the adhesion was improved by optimizing the shape of the outer section of a the rubber, this study ensured the development of a reliable torque rod assembly.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.139-146
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• 2014

Recently, in field of bridge construction, modular technology has been studied to reduce construction period, traffic impact and environmental impact. This study is a part of research related to the modular bridges. The aim of the study is to analyze the structural behavior and evaluate a serviceability for transverse connection of modular slab bridge. A total of four specimens were fabricated. including a control beam for finding the maximum load by static test. And one control beam and two segmental beams were fabricated for cyclic loading test. As the test result, the beams that were introduced 100% of the design prestressing force showed a smaller maximum deflection, residual deflection and crack width than the control beam. The beam for serviceability evaluation was satisfied with structural serviceability limits of the deflection and crack.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.501-509
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• 2016

We propose a method to improve the robustness of speaker verification on short test utterances. The accuracy of the state-of-the-art i-vector/probabilistic linear discriminant analysis systems can be degraded when testing utterance durations are short. The proposed method compensates for utterance variations of short test feature vectors using deep neural networks. We design three different types of DNN (Deep Neural Network) structures which are trained with different target output vectors. Each DNN is trained to minimize the discrepancy between the feed-forwarded output of a given short utterance feature and its original long utterance feature. We use short 2-10 s condition of the NIST (National Institute of Standards Technology, U.S.) 2008 SRE (Speaker Recognition Evaluation) corpus to evaluate the method. The experimental results show that the proposed method reduces the minimum detection cost relative to the baseline system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.315-323
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• 2016

This study examined the durability and method for making a mockup of bobsled tracks for constructing a bobsled stadium, which is a sport in the Winter Olympics. As bobsleigh games are very fast and dangerous, a safety design for players and a precise construction using highly efficient shotcrete is necessary. Moreover, a general molding construction is difficult because bobsleigh tracks are composed of various curves and slopes, and it is necessary to construct them using high-strength and high durability materials. The developed method for making a mockup and performing durability evaluation of bobsleigh tracks through this research will be applied in the construction of the 2018 Pyeongchang Winter Olympics Sliding centre and bobsleigh tracks using domestic techniques.

• Journal of Dental Anesthesia and Pain Medicine
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• v.19 no.5
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• pp.277-288
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• 2019

Background: This study evaluated the efficacy of virtual reality (VR) distraction and counter-stimulation (CS) on dental anxiety and pain perception to local anesthesia in children. Methods: A prospective, randomized, single-blinded interventional clinical trial with a parallel design was used. Seventy children 7-11 years old who required local anesthesia (LA) for pulp therapy or tooth extraction were recruited and allocated to two groups with equal distribution based on the intervention. Group CS (n = 35) received CS and Group VR (n = 35) received VR distraction with ANTVR glasses. Anxiety levels (using pulse rate) were evaluated before, during, and after administration of local anesthesia, while pain perception was assessed immediately after the injection. Wong-Baker faces pain-rating scale (WBFPS), visual analog scale (VAS), and Venham's clinical anxiety rating scale (VCARS) were used for pain evaluation. Student's t-test was used to test the mean difference between groups, and repeated measures ANOVA was used to test the mean difference of pulse rates. Results: Significant differences in mean pulse rates were observed in both groups, while children in the VR group had a higher reduction (P < 0.05), and the mean VCARS scores were significant in the VR group (P < 0.05). Mean WBFPS scores showed less pain perception to LA needle prick in the CS group while the same change was observed in the VR group with VAS scores. Conclusions: VR distraction is better than CS for reducing anxiety to injection in children undergoing extraction and pulpectomy.