• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.6
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• pp.825-836
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• 2022

Micropiles can be used to support additional load in extended building structures. However, their use brings about a risk of exceeding the bearing capacity of existing piles. In this study, pre-compression was applied to distribute the load of an existing building to micropiles, and an indoor loading test was performed to confirm the structural applicability of a wedge-type anchorage device designed to improve its capacity. According to the test results, the maximum strain of the anchorage device was 0.63 times that of the yield strain, and the amount of slip generated at the time of anchorage was 0.11 mm, satisfying structural standards. In addition, using MIDAS GTS, a geotechnical finite element analysis software, the effect of the size of the pre-compression, the thickness of the soil layer, and the ground conditions around the tip on the reaction force of the existing piles and micropiles were analyzed. From the numerical analysis, as the size of the pre-compression load increased, the reaction force of the existing pile decreased, resulting in a reduction rate of up to 36 %. In addition, as the soil layer increased by 5 m, the reduction rate decreased by 4 %, and when the ground condition at the tip of the micropile was weathered rock, the reduction rate increased by 14 % compared with that of weathered soil.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.1
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• pp.150-165
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• 1998

For the purpose of evaluating the effect of both direct retainer design and bony absorption degree around abutment of indirect retainer on the supporting tissue of abutment of indirect retainer, dislodging force was transmitted to unilateral distal extension RPD bases. Analysis of stress distributed within the supporting tissue around abutment of indirect retainer was carried out. Using three-dimensional photoelastic stress analysis method and the conclusion is a follows. 1. According to the extent of force which the direct retainer of the most distal abutment tooth, the amount of force transmitted to the abutment tooth of indirect retainer was small. 2. Of all the cases, Mandibular first premolar which was used abutment tooth of indirect retainer, buccal, mesial and distal sides represented compression stress and lingual side represented tensile stress. 3. The more bone resorption of abutment tooth of indirect retainer, the more distortion of buccal and distal side of abutment tooth was existed and the extent of compression stress which was existed and distal side to abutment tooth was large. 4. When the alveolar bone around the abutment with indircet retainer is normal. The amount of force transmitted on abutment with indirect retainer was small in the order of Akers clasp, RPA clasp, RPI clasp. 5. When the alveolar bone around the abutment with indirect retainer has been absorbed 20% and 30%, the amount of force transmitted on abutment with indirect retainer was small in the order of RPA calsp, RPI clasp, Akers clasp. 6. When denture is displaced, shape of the direct retainer reciprocating abutment affect much the function of indirect retainer.

• Journal of Korean Neurosurgical Society
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• v.37 no.3
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• pp.217-222
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• 2005

Objective: To achieve optimal fit of implant, it is necessary to bend the implant during spine surgery. Bending procedure may decrease stiffness of plate especially made of titanium and stainless steel. Typically titanium suffers adverse effects including early crack propagation when it is bent. We investigate whether 6 degree bending of titanium plates would decrease the stiffness after full cyclic loading by comparing with non-bending titanium plates group. Methods: Authors experimented 40 titanium alloy plates of 57mm in length, manufactured by 5 different companies. Total 40 plates were divided into two groups (20 bent plates for experimental group and 20 non-bent plates for control group). Twenty plates of experimental group were bent to 6 degree with 3-point bending technique and verified with image analyzer. Using the electron microscope, we sought for a initial crack before and after 3-point bending. Mechanical testing by means of 6000 cyclic axial-compression loading of 35N in compression with moment arm of 35mm-1.1 Nm was conducted on each plate and followed by the electron microscopic examination to detect crack or fissure on plates. Results: The stiffness was decreased after 6000 cyclic loading, but there was no statistically significant difference in stiffness between experimental and control group. There was no evidence of change in grain structure on the electron microscopic magnification. Conclusion: The titanium cervical plates can be bent to 6 degree without any crack or weakness of plate. We also assume that minimal bending may increase the resistance to fatigue fracture in cervical flexion-extension movement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2479-2485
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• 2013

In this paper, we present a design for solid-state radar SSPA with sequential bias. We apply to variable extension pulse generator to eliminate signal distortion which is caused by bias rising/falling delay of power amplifier. There is an optimum impedance matching circuit to have high efficiency of GaN-power device by measuring microwave characteristics through load-pull method. The designed SSPA is consisted of pre-amplifier, drive-amplifier and main-amplifier as a three stages to apply for X-Band solid-state radar. Thereby we made a 200W SSPA which has output pulse maximum power shows 53.67dBm and its average power is 52.85dBm. The optimum design of transceiver module for solid-state pulse compression radar which is presented in this dissertation, it can be available to miniaturize and to improve the radar performances through additional research for digital radar from now on.

• Journal of Korea Multimedia Society
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• v.8 no.2
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• pp.201-210
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• 2005

This paper proposes a power efficient 2-dimensional DCT/IDCT architecture driven by input data to be processed. The architecture achieves low power by taking advantage of the typically large fraction of zero and small-valued input processing data in video and image data compression. In particular, it skips multiplication by zero and dynamically activates/deactivates required bit-slices of fine-grain bit partitioned adders within multipliers and accumulators using simple input ANDing and bit-slice MASKing. The processed results from 1-D DCT/IDCT do not have unnecessary sign extension bits (SEBs), which are used for further power reduction in matrix transposer. The results extracted by bit-level transition activity simulations indicate significant power reduction compared to conventional designs.

• Journal of the Korea Fashion and Costume Design Association
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• v.21 no.4
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• pp.17-26
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• 2019

This research aims to obtain useful data on the development of compression garment products with high-stretch knitted materials. Using nylon SCY, four specimens were knitted. Then, appearance (width, length, weight, thickness), stretch property (stretch, recovery) and clothing pressure were measured and their interrelation was analyzed. In the comparison of appearance features, yarn floating caused shrinkage in both course and wale directions of the specimens. Yarn overlapping by tucking caused a release in the course direction and shrinkage in the wale direction. Also, structural change was affected by the weight and thickness change of the knitted fabric. In the analysis of fabric stretch, yarn floating reduced the extension in course direction and increased that in wale direction of the knitted fabric. However, yarn overlapping reduced the elongation in both directions. In the analysis of recovery, yarn floating and overlapping raised fabric recovery in both directions, and tuck structure was superior to float in recovery. In the analysis of clothing pressure, 'Plain-Float' structured fabrics showed a higher clothing pressure than 'Plain' and the clothing pressure value of 'Plain-Tuck' was lower than that of 'Plain'. As for the correlation between fabric appearance, stretch property, and clothing pressure, the appearance change in course direction had a major influence on the clothing pressure. The shrinkage of appearance led to a decrease in stretch and an increase in clothing pressure.

• Journal of the Korea Fashion and Costume Design Association
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• v.12 no.4
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• pp.197-206
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• 2010

The purpose of this study is to dye hanji/cotton fabrics using persimmon juice and to investigate the change in the hand fabrics. Using the Kawabata Evaluation System, we have examined the changes in the physical properties, primary hand value and total hand value. The dynamic characteristics of hanji/cotton fabrics have been explored by tensile, shear, bending, compression, surface properties, thickness and weight. As a result, it can be seen that the linearity of load-extension and tensile resilience are increased with the increase of the concentration and dyeing times of persimmon juice and tensile energy is decreased in the same condition. These behaviors are shown in the compression properties. Although the mechanism of persimmon juice dyeing has been widely discussed, it means that the fabrics dyed with persimmon juice become stiffened and the elasticity is increased with the introduction of persimmon on the fabrics studied. Bending rigidity and hysteresis of the bending moment are increased with the increase of the concentration and dyeing times of persimmon juice. Also, Geometrical roughness, expressed in SMD is increased with increasing the concentration and dyeing times of persimmon juice, compared with as-received. It indicates that these results are due to the geometric structure of hanji yarn and the introduction of persimmon juice on the fabrics studied. The fullness and softness with the soft feeing are increased a little due to the tannin component of persimmon juice introduced on the fiber surface.

• Fashion & Textile Research Journal
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• v.8 no.3
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• pp.357-362
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• 2006

This study is to evaluate the objective sensibility of the commercial lining fabrics. Five kinds of the linings were collected by adding taffetas with four kinds of fibers (polyester, nylon, rayon, and acetate) to one polyester stretch fabric. The six basic mechanical and hand properties were studied by using KES-FB system (Kawabata Evaluation System). The result of measuring the mechanical properties shows that polyester has high bending rigidity (B), that polyester-stretch has a high value of linearity of load-extension curve (LT), tensile energy (WT), tensile resilience (RT), and coefficient of friction (MIU) and a low value of bending rigidity(B), shear property, and geometrical roughness (SMD). The nylon has a high value of bending rigidity (B), shear property, and compression resilience (RC). The rayon has a high value of coefficient of friction (MIU) and linearity of compression-thickness curve (LC) and a low value of shear property, and the acetate has a low value of shear property. The result of hand value shows that polyester, nylon, and acetate are a high value of KOSHI (stiffness), NUMERI (smoothness), and FUKURAM (fullness & softness), and they feel stiff and massive, that rayon has a low value of NUMERI and FUKURAMI. The total result of hand value shows that polyester taffeta and polyester stretch fabric are about the same as the best material for the lining of a woman's dress for spring and summer, and the next thing is acetate, but nylon and rayon are somewhat inferior materials. This provides a fundamental data for the comfortable clothing production of a higher value-added product through the study on the mechanical and hand properties of the lining as well as the right side of fabrics.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup2
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• pp.254-258
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• 2001

Objective : The terminology of degenerative disc disease lacks official standardization. Lacks of such standardization may provoke some clinical and litigation problems. The authors investigated interobserver and intraobserver variability in interpretation of lumbar disc abnormality. Methods : Magnetic resonance imaging studies of the lumbar spine performed prospectively in 50 patients, were read blindly by three doctors dealing spinal disorders, using two nomenclature. Nomenclature I was normal, bulging, protrusion, extrusion. Nomenclature II was normal, bulging, herniation without neural compression, with neural compression. Intraobserver and interobserver variation were measured statistically. Results : Interobserver agreement was 70.4-80.8% for nomenclature I, 76.2-80.2% for nomenclature II. Intraobserver agreement was 84.0-88.0% for nomenclature I, 79.2-86.8% for nomenclature II. Interobserver Kappa statistic was 0.53-0.56 for nomenclature I, 0.54-0.57 for nomenclature II. Intraobserver Kappa statistic was 0.60-0.85 for nomenclature I, 0.53-0.72 for nomenclature II. Conclusion : Experienced doctors showed only moderate interobserver agreement when interpreting disc status on lumbar magnetic resonance imaging. Intraobserver agreement was superior to interbserver. The standardization of nomenclatures for lumbar disc extension beyond interspace are needed.

• Geomechanics and Engineering
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• v.19 no.1
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• pp.49-60
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• 2019

Crack instability propagation during coal and rock mass failure is the main reason for electromagnetic radiation (EMR) generation. However, original cracks on coal and rock mass are hard to study, making it complex to reveal EMR laws and mechanisms. In this paper, we prefabricated cracks of different inclinations in coal and rock samples as the analogues of the native cracks, carried out uniaxial compression experiments using these coal and rock samples, explored, the effects of the prefabricated cracks on EMR laws, and verified these laws by measuring the surface potential signals. The results show that prefabricated cracks are the main factor leading to the failure of coal and rock samples. When the inclination between the prefabricated crack and axial stress is smaller, the wing cracks occur first from the two tips of the prefabricated crack and expand to shear cracks or coplanar secondary cracks whose advance directions are coplanar or nearly coplanar with the prefabricated crack's direction. The sample failure is mainly due to the composited tensile and shear destructions of the wing cracks. When the inclination becomes bigger, the wing cracks appear at the early stage, extend to the direction of the maximum principal stress, and eventually run through both ends of the sample, resulting in the sample's tensile failure. The effect of prefabricated cracks of different inclinations on electromagnetic (EM) signals is different. For samples with prefabricated cracks of smaller inclination, EMR is mainly generated due to the variable motion of free charges generated due to crushing, friction, and slippage between the crack walls. For samples with larger inclination, EMR is generated due to friction and slippage in between the crack walls as well as the charge separation caused by tensile extension at the cracks' tips before sample failure. These conclusions are further verified by the surface potential distribution during the loading process.