• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.295-302
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• 2011

The setting time which is the important element for the determination of slip-up speed of Slip-Form system is the hardening time of early-age concrete when the in place concrete has minimum compressive strength before the concrete appears out of Slip-Form system. But it is very difficult to predict the setting time because it depends on not only the composition ratio of concrete but also various conditions of construction fields. Thus, the technique to estimate accurately and continuously the hardening time of early-age in place concrete during operating Slip-Form system is necessary to guarantee the safety of Slip-Form system and the maintenance of the shape of concrete. Ultrasonic wave-based nondestructive testing methods have the advantages which are accurate and continuous in estimating concrete compressive strength. Of such methods, the method using surface wave which propagates along the surface of material is effective for thick member such as a pylon. Thus, in this paper a study on the determination of slip-up speed for Slip-Form system using surface wave velocity is performed. The relation between the slip-up speed of Slip-Form system and the setting time is formulated, and the surface wave velocity is estimated from continuous wavelet transform of the numerical results for surface wave propagation. Finally, the accuracy of this method according to the distance between the wave source and receivers and the relation between the estimated surface wave velocity and the elastic modulus are investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1093-1100
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• 2014

The purpose of this paper is to suggest a weight-reduction design method for the hybrid carbody of a high-speed maglev train that uses aluminum extrusion profiles and sandwich composites. A sandwich composite was used on the roof as a secondary member to minimize the weight. In order to assemble the sandwich composite roof and aluminum extrusion side frame of the carbody using welding, a guide aluminum frame located at the four sides of the sandwich composite roof was introduced in this study. The clamping force of this guide aluminum frame was verified by three-point bending test. The structural integrity and crashworthiness of the hybrid carbody of a high-speed maglev train were evaluated and verified according to the Korean Railway Safety Law using a commercial finite element analysis program. The results showed that the hybrid carbody composed of aluminum extrusion frames and a sandwich composite roof was lighter in weight than a carbody made only of aluminum extrusion profiles and had better structural performance.

• Journal of Energy Engineering
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• v.20 no.2
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• pp.90-95
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• 2011

This study was conducted to judge requalification of cylinders by assessing composite flaws such as scratches, cuts, and gouges damaging on the composite of Type III cylinders for compressed natural gas vehicles. As a result of the flaw tolerance test, all specimens have satisfied with minimum requirement cycles according to damage levels based on ISO 19078 and cyclic performance for pressure showed beyond twenty thousands in damage level 1 and 2, and did eighteen thousands to twenty-one thousands in damage level 3. Eight of twelve specimens failed the test due to composite flaws and the rest of the cylinders failed regardless of flaws. The results of Finite Element Method followed by the computer simulation indicated that the stress of 79.5 MPa calculated on the flaw model of $1.25\;mm{\times}200\;mm$ and the stress of 66.6 MPa on the non-flaw model when the service pressure applied to inside of cylinder. The difference between the models is about 19.37%. We concluded that this difference influences fatigue life and this flaw model is a critical value affecting cyclic performance of cylinders.

• Science of Emotion and Sensibility
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• v.21 no.2
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• pp.15-28
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• 2018

The purpose of this study was to conduct eye-tracking experiments to target large spaces and to analyze the characteristics of pupil gaze by gender. By analyzing the change of pupil size in the eye-tracking experiment, we suggest a template for objective and scientific analyses of gender observation data. Additionally, based on the difference between gender and time to pupil size change, we noted the characteristic of time that gather the visual perception data information and showed that females attend to interesting elements of visual information one to two seconds slower than males. In the initial "$1sec{\rightarrow}2sec$", the pupil size has been increased in leap condition of male and in fixed condition of female. In addition, if condition limits to fixed observation to view the change rates on gender then the pupil size of female was larger than male before 9 seconds, while male's pupil size was larger after 9 seconds. This indicates that females obtain visual information through a relatively larger pupil size during the first 1-8 seconds after stimulus presentation, while males acquire it between 10-15 seconds after input. However, based on the result that the pupil size of female was larger than male on the change of observation time, the pupil size movement on female was energized to watch more interest element after a certain period of time.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.6
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• pp.897-908
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• 2019

The objective of this study is to evaluate the field support performance of highperformance lattice girder (BK-Lattice Girder) by using numerical analysis. Three types (50, 70, 95-type) of existing and high performance lattice girders were applied to the cross section of highway 2, 3, and 4 lane tunnels to compare the supporting performance. The numerical analysis was the finite element method and the lattice girder was modeled in three dimensions with an elasto-plastic frame. The ground was modeled as a spring receiving only compression. The load was applied as a concentrated load on the central ceiling of the tunnel section. The yield strengths of the lattice girders were determined from the numerical results to compare the supporting performance of lattice girder. In case of 50-type, the yield strengths of high-performance lattice girders were increased by 6.7~10.0% compared with those of the existing lattice girders. In the case of 70-type, the high-performance lattice girders increased yield strengths by 12.1~14.9% than the existing lattice girder. In the case of 95-type, the high-performance lattice girders increased yield strengths by 13.3~20.0% than the existing lattice girder. As a result of numerical analysis, it was considered that the high-performance lattice girder supported better than the existing lattice girder when only the lattice girders were constructed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.4
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• pp.403-413
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• 2007

As rock bolts become one of the main support systems in tunnels and underground structures, the integrity of the rock bolts affects the safety of these types of structures. The purpose of this study is the evaluation of rock bolt integrity using Fourier and wavelet transforms of the guided ultrasonic waves. After five rock bolt specimens with various defect ratios are embedded into a large scale concrete block, guided waves are generated by a PZT (lead zirconate titanate) element and measured by an acoustic emission (AE) sensor. The captured signals are analyzed in the frequency domain using the Fourier transform, and in the time-frequency domain using the wavelet transform based on a Gabor wavelet. The spectrum obtained from the Fourier transform shows that a portion of high frequency contents increases with increase in the defect ratio. Peak values in the time-frequency domain represent the interval of travel time of each echo. The energy velocities of the guided waves increase with the defect ratio. This study shows that the spectrum ratio and the energy velocity may be indicators fur the evaluation of rock bolt integrity.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7171-7177
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• 2013

Purpose: To compare the safety and efficacy of first-line chemotherapy regimen with or without doxorubicin in treating patients with advanced soft tissue sarcoma (STS). Patients and Methods: We retrospectively analyzed a cohort of 56 patients histologically confirmed with STS who were treated at Jiangsu Cancer Hospital and Research Institute from July 2011 to June 2012.The basic element of first line chemotherapy contained epirubicin in group B and lacked epirubicin in group A. Response was assessed using RECIST criteria. The Kaplan-Meier method was used to estimate progress free survival (PFS). Results: According to RECIST criteria, patients in group treated by chemotherapy without epirubicin, the objective response (OR) ratio was 6.5 % (CR0%+PR6.5%). Disease control rate (DCR=CR+PR+SD) was 25.8% with a median follow-up of 14.6 months, including 2 patients achieving a partial response (PR 6.5%) and a stable response (SD 19.4%) in 6. In group B with epirubicin based regimens, no patient had complete response, PR (28 %) was observed in 7 and SD (24 %) in 6. DCR was observed in 13 patients (52%). By Fisher's exact test, the DCR difference between the two groups was statistically significant (p=0.046). In group A, median PFS was 3.0 months (95%CI:2.1-3.8), compared with 4.0 months (95% CI:3.03-4.97) in group B (p=0.0397 by log-rank test). Epirubicin based chemotherapy and ECOG performance status 0-1 were identified as favorable factors for progression in our cohort of patients. Differences of nonhematologic and hematologic toxicities were not statistically significant between the two groups, and the addition of epirobicin was not associated with cardiac toxicity (p=0.446). Conclusion: Our study demonstrates that epirubicin-based chemotherapy is effective and well tolerated, and is superior to chemotherapy without epirubicin regarding efficacy. Therefore it is recommended that epirubicin-based chemotherapy should be considered as first line for patients with advanced STS.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.139-152
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• 2006

A spent fuel storage cask is required to prove the safety of a canister under a hypothetical accidental drop condition. A hypothetical accidental drop condition means that a canister is assumed to be a lee drop on to a pad of the storage cask during loading it into a storage cask. A pad of the storage cask absorbs shock to maintain the structural integrities of a canister under a hypothetical accidental drop condition. In this paper a finite element analysis for various pad structures was carried out to improve the structural integrity of a canister under a hypothetical accidental drop condition. A pad of a storage cask was designed a steel structure with concrete. The 1/4 height of a pad was modified with a structure composed of a steel and a polyurethane foam as a impact limiter. The effect of a shape of a steel structure was studied. The effects of the thickness of a steel structure and the density of a polyurethane foam was also studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.98-106
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• 2020

This study examined the integrity of diesel engines for underwater vessels through failure analysis, analyzed the causes of abnormal diesel engine stoppage during building and examined the integrity of secondary damages. The diesel engine stoppage was analyzed by checking the temperature change of the piston before and after the abnormality and checking the damage. In addition, in order to analyze the secondary damage caused by the explosion, the tensile and compressive stresses transmitted to the crankshaft, the core part of the diesel engine, were calculated, and the stress distribution was examined through finite element analysis, but the crankshaft was designed by safety. It was confirmed that there was no damage to the crankcase even when the diesel engine was taken out of the ship and closely inspected. The integrity of the crank shaft was verified in advance for the occurrence of diesel engine emergency shutdown accidents through this research result. Therefore, the inspection and restoration were carried out to the minimum extent, and the quality of diesel engines was secured. This study is expected to be used as a reference for ensuring soundness in any future review of diesel engine quality problems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.123-131
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• 2018

This study analyzed the collapse course of a mud stone cut slope during the construction of a express and suggested a countermeasure. Experiments were carried out on bedrock mudstone to investigate the engineering characteristics and the slope stability analysis at the time the design was reviewed. In addition, stability analysis, considering the strength softening characteristics of the slope due to the Swelling-Slaking phenomenon, was also performed. As a result of the Swelling-Slaking test, the slake durability was Low-Medium, and the swell potential was Very Low. A review of the stability analysis performed at the time of the design showed different results from the actual results because LEM analysis had been performed without considering the engineering characteristics of mudstone. As a result of additional stability analysis considering the strength softening characteristics, the slope collapse point and the maximum shear strain point of the stability analysis were the same and the standard safety factor was not satisfied. As a countermeasure, a slope mitigation method was found to be most appropriate. The mitigation slope was calculated by Finite element Analysis. A comparison with BIPS to determine the applicability of a mitigation slope revealed most of the unconsolidated mudstone.