• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.1017-1022
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• 2001

The bend resistance of coated reinforcing bar is greatly influenced by adhesion strength of bar and coating materials and transformation of coating materials to the bar. Expecially, tearing state or a limited microscopic cracks are predicted on the inside and outside of bending angle because of adhesion strength and elongation is very different with types of polymer materials using bar coating, and these parts are accelerated corrosion as penetration of bar corrosion effects factor. In this study, cement modified polymer are prepared four types and differ from polymer cement ratio of 50% and 100%, coating thickness of 250$\mu$m and 450$\mu$m, coating number, curing age of 3, 7, 14 and 280days, and then tested bend resistance as bending angle $90^{\circ}$, $135^{\circ}$ and $180^{\circ}$ for observe the microscopic demage effect according as bar bend. From the test results, when is used cement modified polymer as coating materials of bar, St/BA is showed excellent bend resistance than a polyacrylic emulsion and SBR because of softness. But it is to need attention because as coating parts are pressed down and tearing, also experimental study is proceeded to corrosion potential on the inside and outside of coated reinforcing bar.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.650-655
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• 1993

Carbon/epoxy composite(CFRP) coupons previously damaged by low velocity impact were tested under static tensile loading and microscope progress of damage was characterized by ultrasonic C-scan, Scanning Acoustic Microscopy (SAM) and Acoustic Emission(AE) techniques which were based on the application of elastic waves. The degress of impact damage has been correlated with the AE activity during monotonic or loading/unloading tensile testing as well as the result of ultrasonic test. The coupons were subjected to impact velocities ranged from 0.71 to 2.17 m/sec, which introduced the amount of damage rated as 0%, 10%, 30%, and 50% with reference to the total absorbed energy at fracture. Special attention was paid to determine optimal AE parameters to characterize the microscopic fracture process and to predict the residual strength of composite laminates. AE RMS voltage during the early stage of tensile loading was found an effective parameter to quantify the degree of impact damage. It was also found that the Felicity ratio is closely related to the stacking sequence and the residual strength of the CFRP laminates.

• Korean Journal of Veterinary Research
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• v.33 no.1
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• pp.125-129
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• 1993

An acute fatal infectious disease in rabbits has been outbroken in Korea since 1985. This disease has been characterized as an acute hepatitis caused by viruses. However, viral pathogenesis in rabbit viral hepatitis leading to sudden death remain unclear. This report dealt with the electron microscopic findings on the spleen of experimentally infected rabbits, because spleen is one of the affected organs which have high titer of virus by a haemagglutination test. A typical crystalline array of virus was not found in the splenic cells of infected rabbits with acute hepatitis. Virus-like particles were seen within the phagosome of macrophages of the spleen. Ultrastructural changes in the spleen were severe with the lapse of time after inoculation. From these results, virus-like particles in the spleen were supposed to be phagocytosed by macrophage during viremia, while active replication of virus occurred in the liver. It was concluded that sudden death in this viral disease was caused by hepatic coma and/or circulatory disturbance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2520-2528
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• 2000

Mechanical and physical properties of composite materials make a great difference due to their cure process condition. In order to clarify the effect of cure process condition on the microscopic damage behavior and failure mechanism of Carbon/Epoxy composites, three point bend test has been performed. For this purpose, two kinds of specimens with single adhesive and multiple adhesive layers were prepared. For single adhesive layer, four different types of specimen were used, that is, non-sanding, sanding, cocured, laminated specimens. Three different types of specimen were also used for the multiple adhesive layer, non-sanding, sanding, cocured specimens. Acoustic emission technique has also been employed to monitor the damage progresses associated with each micro-failure mechanism. The characteristics of AE parameters associated with micro-failure mechanism of each specimen were discussed.

• Transactions of Materials Processing
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• v.17 no.1
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• pp.46-51
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• 2008

Polycrystalline materials such as steels(BCC) and aluminum alloys(FCC) show the strain hardening and the strain rate hardening during the plastic deformation. The strain hardening is induced by deformation resistance of dislocation glide on some crystallographic systems and increase of the dislocation density on grain boundaries or inner grain. However, the phenomenon of the strain rate hardening is not demonstrated distinctly in the rage of $10^{-2}$ to $10^2/sec$ strain rate. In this paper, tensile tests for various strain rates are performed in the rage of $10^{-2}$ to $10^2/sec$ then, specimens are extracted on the same strain position to investigate the microscopic behavior of deformed materials. The extracted specimens are investigated by using the electron backscattered diffraction(EBSD) and transmission electron microscopy(TEM) results which show the effect of texture orientation, grain size and dislocation behavior on the strain rate hardening.

• Geomechanics and Engineering
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• v.35 no.5
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• pp.475-486
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• 2023

Ballast particles have an irregular shape and are discrete in nature. Due to the discrete nature of ballast, it exhibits complex mechanical behaviour under loading conditions. The discrete element method (DEM) can model the behaviour of discrete particles under a multitude of loading conditions. DEM is used in this paper to simulate a series of three-dimensional direct shear tests in order to investigate the shear behaviour of railway ballast and its interaction at the microscopic level. Particle flow code in three dimension (PFC3D) models the irregular shape of ballast particles as clump particles. To investigate the influence of particle size distribution (PSD), real PSD of Indian railway ballast specification IRS:GE:1:2004, China high-speed rail (HSR) and French rail specifications are generated. PFC3D built-in linear contact model is used to simulate the interaction of ballast particles under various normal stresses, shearing rate and shear box sizes. The results indicate how shear resistance and volumetric changes in ballast assembly are affected by normal stress, shearing rate, PSD and shear box size. In addition to macroscopic behaviour, DEM represents the microscopic behaviour of ballast particles in the form of particle displacement at different stages of the shearing process.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.131-136
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• 2013

TSV based 3D ICs have been widely developed with new problems at die and IC levels. It is imperative to test at post-bond as well as pre-bond to achieve high reliability and yield. This paper introduces a new testable design technique which not only test microscopic defects at TSV input/output contact at a die but also test interconnect defects at a stacked IC. IEEE 1500 wrapper cells are augmented and through at-speed tests for pre-bond die and post-bond IC, known-good-die and defect free 3D IC can be massively manufactured+.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.11 no.1
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• pp.37-48
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• 2005

Objects: This study is designed to analysis improvement and maintaince of trunk stability targeting patients who need post operative rehabilitation exercise after undergoing opened microscopic laser discectomy(OMLD) due to HNP. Method: Between March 2004 and February 2005 a total sixty patients who underwent OMLD due to $L_4/L_5$, $L_5/S_1$ HNP and who agreed to the experiment were subject for this study. Experimental group consisted of 18 subjects, and they underwent 45 minutes dynamic lumbar stabilization exercise And control group consisted of 18 subjects who conducted conservative physical therapy based on the use of physical modality for 45 minutes except to exercise. Results: Experimental group that was lumbar extensor's isometric peak torque, weight distribution of both leg, trunk muscle balance and Oswestry LBP disability index increased during 12 weeks in a statistically significant manner compared to before exercise (p<.05). When re-test was tried, isometric peak torque (p>.05) and Oswestry LBP disability index(p<.05) maintained 12th week level or improved. Weight distribution rate of both leg and trunk muscle balance maintained the level of 8th week of exercise execution(p<.05). Control group that was lumbar extensor's isometric peak torque, weight distribution rate of both leg and trunk muscle balance aggravated during 12 weeks compared to pre-test(p>.05) But, Oswestry LBP disability index increased in a statistically significant level compared to pre-test(p<.05). When re-test was tried, isometric peak torque increased slightly compared to pre-test, but decreased when at least $60^{\circ}$ flexion angle(p>.05). Weight distribution rate of both leg and trunk muscle balance also aggravated compared to pre-test(p>.05), and Oswestry LBP disability index was similar to the 4th week of physical therapy execution(p>.05). Conclusion: Successive postoperative Especially, Application of dynamic lumbar stabilization exercise program is important than traditional lumbar strengthening exercise program in the maintaince of spinal stability.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.96-104
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• 2008

In this study, the observation of test pieces with an optical microscope was carried out after fabricating 4 groups of standard lacquer, in order to inquire into the ancient lacquering techniques. Group I had transparent reddish brown color, and the part of layer was indefinite, and the layer polished was easily distinguished. Group II had mostly transparent yellowish brown color, and it was possibility distinguished the layers when they were varnished with mixed lacquer after prime coating, and when they were varnished with lacquer as the prime coating. Group III set up membrane in the hardening process of the lacquer, and the lacquer and the unsaturated fatty acid of internal part was dried, so the top layer and the lacquer layer were separated and observed. Group IV: When the lacquer coat film of Group IV test pieces were observed in polarized light, the ferrous components were seen as the black and red color were mixed, and the silica crystals of silty soil were distinguished by reflection of lights. And the colors were distinguished as the lacquer layer of ruddle had red color, and the mixed lacquer of reddish lacquer and ruddle had the deep red color at the top and the bottom, but the middle part had the bright red color.

• Journal of Preventive Medicine and Public Health
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• v.18 no.1
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• pp.41-50
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• 1985

To find out the differences in medical practice according to the environment of patient care and managerial situation of the medical care institutions, normal spontaneous vaginal delivery and acute appendicitis were selected, which is suitable for comparison because of their high comparability. A total of 473 cases of normal spontaneous vaginal delivery and 408 cases of acute appendicitis was sampled from the claims to Korea Medical Insurance Cooperations during January to June 1984. Complicated cases were excluded from population and sampling was restricted from 40 to 60 percentile for total charges by the type of medical care facility in order to rule out the influence originating from case mix. Important items representing type and quantity of medical care service were compared by type of facility. Major findings are as follows : 1. University hospital shows the highest in charges per case and decrease in order of general hospital, and clinic. 2. In case of normal spontaneous vaginal delivery, average length of stay shows statistically significant difference by type of facility. 3. Charge amount for each service item affected by practice pattern shows statistically significant difference mostly by type of facility. It is suggested that medical practice pattern is different by type of facility for medical services. 4. Difference in total medical expenditure by type of facility is affected more with charges for materials, consumables and drugs than with fee for service activity. 5. In administering drugs to patients, hospital and clinic show higher injection rate than university and general hospital. 6. Clinical Laboratory tests were common in order of uninalysis, hemoglobin, hematocrit, white blood cell count, urine microscopic examination in cases of normal spontaneous vaginal delivery; white blood cell count, urinalysis, hemoglobin, hematocrit, urine microscopic examination, white blood cell differential count, in cases of acute appendicitis. 7. The result for Laboratory test and Radiologic study shows extreme difference by type of facility. Test rate is lowest in clinic and increase hospital, general hospital, and university hospital in order, both in type and frequency.