• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.597-605
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• 2009

The safety of expressway bridges was estimated by checking the external condition rank based on the nondestructive inspection and material test and by measuring load carrying capacity based on the result of load test. Although the load carrying capacity of the bridges was clearly low compared to the design standard, it was examined that many of the bridges have good external condition rank relatively. Also, it can be assured that load carrying capacity shows a considerable difference according to various condition even though the bridges have similar construction year and a structural type. Therefore, this study showed various problems of the current safety measurement of expressway bridges by considering the status of the expressway bridges, external condition rank, and method of safety diagnosis and repair, rehabilitation for maintenance. Based on the existing data of over 400 expressway bridges, the load carrying capacity was analyzed quantitatively considering bridge type, serviced life, design live load, external condition rank and traffic count as variables. The result of this study will be expected to provide the basic information for a reasonable safety assessment of expressway bridge.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.263-272
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• 2019

This paper describes the results of bearing capacity using field loading test of pile, in order to extend the applicability of drilled shaft with mid-size, and the results were compared with the prediction results of design bearing capacity by empirical formular. The static load test result showed that the allowable bearing capacity of high pile strength was about 2.4 times higher than that of low pile strength. The dynamic load test result showed that the allowable bearing capacity of high pile strength was about 1.4 times~1.5 times higher than that of low pile strength. The comparison result of allowable bearing capacity between static and dynamic load test showed that the difference of allowable load ranged from 3% to 6% under the same settlement conditions. As a result of comparing the ultimate bearing capacity by load test and design bearing capacity, it was found that the FHWA proposed equation could be more reasonable than the other proposed equation in load sharing ratios of end bearing and skin friction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.170-177
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• 2020

This study examined the clamping force control method and the braking performance test results of an electromechanical brake (EMB) using braking test equipment. Most of the studies related to EMBs have been carried out in the automotive field, dealing mainly with the static test results for various control methods. On the other hand, this study performed a dynamic performance evaluation. The three-phase interior permanent magnet synchronous motor (IPMSM) was applied to drive the actuator of the EMB, and the analysis was verified by JMAG(Ver. 18.0), which is finite element method (FEM) software. The current control, speed control, and position control were used for clamping force control of the EMB, and the maximum torque per ampere (MTPA) control was applied to the current controller for efficient control. The EMB's emergency braking deceleration performance was tested in the same way as conventional pneumatic brake systems when the wheel of a train rotates at 110 km/h, 230 km/h, and 300 km/h. The emergency braking time, with the wheel stopped completely at the maximum rotational speed, was approximately 73 seconds. The similarity of the braking time and deceleration pattern was verified through a comparison with the performance test results of the pneumatic brake system applied to the next generation high-speed railway vehicle (HEMU-430X).

• Journal of Animal Science and Technology
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• v.45 no.6
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• pp.949-956
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• 2003

For the Exp. 1, a total of sixty pigs(15.95${\pm}$0.09kg average initial body weight) were used in a 28-d growth assay to determine the effects of extruded chinese corn on growth performance and nutrient digestibility in nursery pigs. Dietary treatments included 1) UCORN(U.S. corn-SBM based diet), 2) CCORN(Chinese corn-SBM based diet) and 3) ECCORN(Extruded Chinese corn-SBM based diet). Overall period, average daily gain of pigs fed ECCORN diet was higher than that of pigs fed CCORN diet(547 vs 522 g/d), however, there was not significant difference. On day 10 of the experiment, pigs fed UCORN and ECCORN diet had significantly increased in DM and DE digestibilities compared to pigs fed CCORN diet(P〈0.05). Also, on day 24 of the experiment, pigs fed UCORN and ECCORN diet had a significant increase in DM digestibility compared to pigs fed CCORN diet(P〈0.05). Pigs fed ECCORN diet had significantly increased DE digestibility compared to pigs fed CCORN diet(P〈0.05). For the Exp. 2, three cannulated barrows(54.09kg average initial body weight) were used to determine the apparent ileal digestibilities of amino acids and nutrient digestibility of extruded corn in finishing pigs. Dietary treatments were the same as in Exp. 1. Apparent ileal digestibility of cystine was greater for UCORN and ECCORN than for CCORN(P〈0.05). Apparent digestibility of DM at the total tract was greater for UCORN and ECCORN than for CCORN(P〈0.05). Pigs fed UCORN and ECCORN diet had a significant increase in apparent total tract digestibility of N compared to pigs fed CCORN diet(P〈0.05). In conclusion, the results obtained from these feeding trials suggest that the extruded corn for nursery pigs had affected growth performance and DM and DE digestibilities. In finishing pigs, extruded corn was an effective means to improve apparent total tract digestibilities of DM and N.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.4
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• pp.309-317
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• 2015

In this paper, we proposed the standard test specification for safety and function of hiking stick for the elderly. We have concluded nine factors representing specification of hiking stick through analysis of hiking patents and research papers, products survey of business market, case studies for damaged hiking stick and expert surveys. To test the factors, we designed three different kinds of apparatus to examine twist resistance, stick and tip durability and stick straightness. The sample of hiking sticks purchased from market based on Naver sales ranking top to fifteenth. As a result, we concluded six-standard test specification based on eccentric load, adjustable parts load, hand strap load, basket load, tip load and pull load of hiking stick.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.233-245
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• 2009

Availability of pressuremeter test for evaluation of geotechnical properties of foundation soil into which guardrail post is to be installed is investigated in this study. First, an analysis method of the post based on the pressuremeter test is proposed that can obtain bending moment and load-deformation profiles of the post. Then static horizontal load test onto a small scale guardrail post is performed in order to get bearing capacity and load-deformation pattern of the model post. The obtained results are compared with the load-deformation curves and bearing capacity of the post obtained from the pressuremeter method. In addition horizontal impact test to the post is performed using a model bogie car in order to check failure pattern around the model foundation and to investigate dynamic bearing capacity due to deceleration and inertia force of the soil. It is verified that the pressuremeter test is so useful and reasonal technique to analyze road foundation-post interaction.

• Land and Housing Review
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• v.2 no.4
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• pp.387-395
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• 2011

According to the seismic design criteria for structural buildings in Korea, the ground is classified into 5 types based on the average shear wave velocity measured from elastic wave tests on site and seismic load applied to the structure is estimated. However, elastic wave tests in site, however, on the engineering fill, cannot be performed during the construction period. Therefore, to evaluate shear wave velocity considering field conditions, resonant column (RC) and torsional shear (TS) tests are performed and compared with various elastic wave test results. As a result, if confining pressure for the tests using engineering fill are considered properly, we can obtain similar results comparing with those of elastic wave tests. In addition, by considering the effect of maximum shear modulus and confining pressure by RC/TS tests, n values shows typical values ranging from 0.434 to 0.561 so that utilization of RC/TS tests can be useful to infer shear modulus in field.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.58-63
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• 2018

This work dealt with the design and manufacturing of composite blades of a vertical axis wind turbine system. In this work, aerodynamic and structural designs of sandwich composite blades for a vertical axis wind turbine system were performed. First, the aerodynamic and structural design requirements of the composite blades were investigated. After the structural design was complete, a structural analysis of the wind turbine blades was performed using the finite element analysis method. It was performed with the stress and displacement analysis at the applied load condition. A design modification for the structurally weak part was proposed as a result of the structural analysis. Through another structural analysis, it was confirmed that the final designed blade structure is safe.

• Journal of the Korean GEO-environmental Society
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• v.14 no.7
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• pp.31-38
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• 2013

After debris flow caused damage during recent years, many scholars and engineers have thrown their effort into analyzing risk from debris flow in Korea. But it is hard to predict damage by debris flow taken place in wide area. Recently, SINMAP program is widely well used to estimate the amount of debris flow and its' range. In order to make frequent use of it, the most important thing is selection of accurate input parameters. In-situ experiments, which are avaliable in the mountain, is to be suggested to get dependable input parameters for SINMAP. Those are permeability, cohesion, density, friction angle and thickness in SINMAP. To get those, test pit, block sampling, in-situ density test, auger boring, permeability test on ground surface, borehole shear test and dynamic cone test and so forth were selected. In addition, the reliability of the results will be increased through comparing with those by laboratory tests. Hence, the experiments are hard to enter the sites without temporary road and, if possible, licensing and many times are needed, too. Small size experiments are indeed necessary to get accurate parameters.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.73-80
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• 2006

The shear behavior of four different interfaces consisting of four types of geosynthetics was investigated, and both static and dynamic test for the geosynthetic interfaces were conducted. The monotonic shear experiments were performed by using an inclined board apparatus and large direct shear device. The interface shear strength obtained from the inclined board test was compared with calculated values from large direct shear tests. The comparison results indicated that direct shear tests show high possibility to over-predict the shear strength in the low normal stress range where direct shear tests are not performed. Curved failure envelopes were also obtained for interface cases where two static shear tests were conducted. By comparing the friction angles measured from three tests, i.e. direct shear, inclined board, and shaking table test, it was found that the friction angle might be different depending on the test method and normal stresses applied in the research. Therefore, it was concluded that the testing method should be determined carefully by considering the type of loads and the normal stress expected in the field with using the geosynthetic materials installed in the site.