• Earthquakes and Structures
• /
• v.7 no.5
• /
• pp.753-777
• /
• 2014

This study investigates the behavior of precast concrete cantilever wall systems with new vertical connections under cyclic loading. C-type steel connections for PC wall systems are proposed for the transfer of bending moments between walls in the vertical direction, whereas a shear key in the center of the wall is prepared to transfer shear forces by bearing pressure. The proposed connections are assembled easily because the directions of the slots are different at the edges of the walls. Structural performance characteristics such as the strength, ductility, and failure modes of test specimens were investigated. The longitudinal reinforcing steel bars, which are connected to the C-type connections, yielded first. Ultimate deformation was terminated owing to premature failure of the connections. The strength and deformation obtained from the cross-sectional analysis were generally similar to experimental data.

• Geomechanics and Engineering
• /
• v.5 no.4
• /
• pp.313-329
• /
• 2013

Vetiver grass (Vetiveria zizanioides) is being effectively used in many countries to protect embankment and slopes for their characteristics of having long and strong roots. In this paper, in-situ shear tests of the ground with the vetiver roots have been conducted to investigate the stabilization properties corresponding to the embankment slopes. Numerical analyses have also been performed with the finite element method using elastoplastic subloading $t_{ij}$ model, which can simulate typical soil behavior. It is revealed from field tests that the shear strength of vetiver rooted soil matrix is higher than that of the unreinforced soil. The reinforced soil with vetiver root also shows ductile behavior. The numerical analyses capture well the results of the in-situ shear tests. Effectiveness of vetiver root in geotechnical structures-strip foundation and embankment slope has been evaluated by finite element analyses. It is found that the reinforcement with vetiver root enhances the bearing capacities of the grounds and stabilizes the embankment slopes.

• Proceedings of the KSME Conference
• /
• 2001.06b
• /
• pp.36-41
• /
• 2001

The performance of an inductive position sensor is described by the accuracy and the dynamic characteristics of the sensor. Both of these performance indices are affected by magnetic hysteresis and eddy currents. In this paper, a model of an inductive sensor is presented. This model includes the effects of hysteresis and eddy currents. Computer simulation shows that the sensitivity of the sensor is greatly affected by hysteresis and eddy currents. Repeability error increases with hysteresis and eddy currents effects. Results also show that eddy currents influence more on the sensor performance than hysteresis does. To reduce the effects of hysteresis and eddy currents, the sensor should be made out of thin laminations with high resistivity.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.973-977
• /
• 2004

A pneumatic cylinder used to sliding seal which seal the element one to another in relative motion. It is difficult to accuracy control because of adhesion phenomenon. To confirm this phenomenon, it is carried to friction force test and analysis for bellows type rodless cylinder. In the rodless cylinder of this type, friction force test is very important. Through the theoretical analysis of shock absorber obtained the optimal design of bellows type rodless cylinder. As the result of the friction force test, LM Guide type is suitable for work under low friction force.

• The Journal of the Acoustical Society of Korea
• /
• v.21 no.4
• /
• pp.156-156
• /
• 2002

We apply independent component analysis (ICA) for extracting an optimal basis to the problem of finding efficient features for representing speech signals of a given speaker The speech segments are assumed to be generated by a linear combination of the basis functions, thus the distribution of speech segments of a speaker is modeled by adapting the basis functions so that each source component is statistically independent. The learned basis functions are oriented and localized in both space and frequency, bearing a resemblance to Gabor wavelets. These features are speaker dependent characteristics and to assess their efficiency we performed speaker identification experiments and compared our results with the conventional Fourier-basis. Our results show that the proposed method is more efficient than the conventional Fourier-based features in that they can obtain a higher speaker identification rate.

• Journal of The Korean Astronomical Society
• /
• v.45 no.6
• /
• pp.157-166
• /
• 2012

Using the Submillimeter Array (SMA), we identified two bright hot subcores, MM1a and MM1b (size ~ 1" and mass ~ 0.5 $M_{\odot}$) separated by about 1.600, in the 230 GHz continuum emission toward the massive star-forming region DR21(OH). Both display typical hot core characteristics but have slightly different chemical properties. For example, highly saturated species show stronger emission toward MM1a and seem to be evaporating directly from the grain mantles. In contrast, simple sulfur-bearing species have brighter emission at MM1b. These features indicate that MM1a is at an earlier stage than MM1b, and the small-scale chemical differences between these two cores may result from the age difference of the order of $10^4$ years.

• Journal of Korean Foot and Ankle Society
• /
• v.16 no.1
• /
• pp.9-18
• /
• 2012

Osteochondral lesions of the talus are isolated cartilage and/or bone lesions that are known cause of chronic ankle pain. They can occur as the result of a single acute ankle injury or from repetitive loading of the talus. Technical development in radiologic imaging and ankle arthroscopy have improved diagnostic capabilities for detecting osteochondral lesions. Characteristics which are important in assessing an osteochondral lesions include: the size, the type (chondral, subchondral, cystic), the stability, the displacement, the location, and the containment of lesion. Nonoperative treatment involving period of casting and non-weight-bearing is recommended for acute, non-displaced osteochondral lesions in select pediatric and adolescent patients. Operative treatment is recommended for unstable lesions or failed conservative management. Marrow stimulation techniques (abrasion chondroplasty, multiple drilling, microfracture), osteochondral autograft or allograft, autologous chondrocyte implantation, are frequently employed. The purpose of this article is to review the historical background, etiology, classification systems, diagnostic strategies, and to describe a systematic approach to management of osteochondral lesions of the talus.

• Journal of the Korean Ceramic Society
• /
• v.17 no.1
• /
• pp.13-19
• /
• 1980

Mineral identifications on halloysite in Hadong-Sancheong area and the halloysite bearing clay ii Yeoju, Yesan and Hampyeong-Muan area are carried out by the method of X-ray diffraction, electron microscopy and DTA. Chemical composition of the above minerals are analyzed by means of X-ray-fluorescence. Refractoriness are also measured by refractoriness tester. A standard diagram for quantitative analysis of halloysite is given.

• Steel and Composite Structures
• /
• v.22 no.6
• /
• pp.1391-1415
• /
• 2016

Limit load of pressure bearing structures was reviewed in this article. By means of the finite element analysis, limit load of pressurized cylinder with nozzle was taken as an example. Stress classification method and Elastic-plastic finite element analysis combining with limit load determination methods were used to determine limit load of cylinder with nozzle. Comparison of limit load determined by different methods, the results indicated that limit load determined by linearization method was the smallest. Limit load determined by twice elastic slope criterion was the nearest than experimental results. Elastic-plastic finite element analysis had comparably computational precision, but required time consuming. And then the requirements of computer processing and storage capacity by power system became higher and higher. Most of criteria for limit load estimation included any human factors based on a certain substantive characteristics of experimental results. The reasonable criterion should be objective and operational.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.5
• /
• pp.690-697
• /
• 2012

Novel 8/10 bearingless switched reluctance motor, which can control rotor radial positions with magnetic force, is proposed. The motor has combined characteristics of switched reluctance motor and magnetic bearing. This paper proposes a air-gap control system method of suspending force control in a bearingless switched reluctance motor (BLSRM). The proposed radial force control scheme is independent to the torque winding current. A PI direct current control (DCC) controller and look-up table are used to maintain a constant rotor air-gap. From the analysis and the experimental results, it is shown that the proposed strategy is effective in realizing a naturally decoupled radial force control of BLSRM.