• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.139-142
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• 2004

The object of the present work is the acoustic emission energy analysis of subambient pressure tri-pad slider. Head/disk interaction during start/stop and constant speed were detected by using acoustic emission (AE) test system The frequency spectrum analysis is performed using the AE signal obtained during the head/disk interaction Natural frequency analysis was performed using Ansys program. Acoustic emission energy was calculated for the slider modes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.924-929
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• 2001

The flying height of contact slider is determined by vertical and pitching motions of slider. This paper performed the computer simulation for flying height change of contact slider. It is changed by many parameters, contact stiffness, contact damping, air bearing stiffness ratio, a location of mass center, and so on. Computer simulation is performed for knowing for what change of these parameters influences in flying height of contact slider. Disk surface is modeled in harmonic wave with from 10㎑ to 600㎑. Tri-pad slider is modeled in that contact slider has 2-DOF motion (vertical motion, pitching motion). Tri-pad contact slider is analyzed by numerical analysis method in computer simulation.

• KSTLE International Journal
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• v.5 no.1
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• pp.28-31
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• 2004

The object of the present work is the natural frequency analysis of subambient pressure tri-pad and pico sliders. Head/disk interaction during start/stop and constant speed were detected by using the acoustic emission (AE) test system. The frequency spectrum analysis is performed using the AE signal obtained during the head/disk interaction. The FFT (Fast Fourier Transform) analysis of the AE signals is used to understand the interaction between the AE signal and the state of contact. Natural frequency analysis was performed using the Ansys program. The results indicate acceptable accordance of finite element calculation results with the experimental results.

• Journal of the Korean Wood Science and Technology
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• v.42 no.6
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• pp.740-746
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• 2014

The unripe fruit of cudrania tricuspidata was extracted with 50% ethanol. The crude water-soluble extracts were separated by liquid-liquid separation with n-hexane, ethyl acetate and butanol followed by precipitation with ethanol, and then the water-soluble polysaccharide (F1) was isolated by the fractionation through gel permeation chromatography using preparative PLaquagel-OH column with water. The structure was characterized by monosaccharide composition with HPAEC-PAD, methylation analysis with GC-MS, FT-IR and HPLC. According to the data, F1 was com posed of glucose (22.84 mM), galactose (13.75 mM), arabinose (45.87 mM), xylose (7.49 mM). It was revealed which uronic acid and acetyl group were not attached in F1. And it is constituted of 1-linked arabinose, 1,4-linked arabinose, 1,3-linked glucose, 1,4-linked galactose, 1,4-linked glucose, 1,3,6-linked galactose, 1,3,6-linked glucose and the ratio was showed 1.1 : 1.0 : 4.9 : 7.5 : 3.0 : 3.1 : 1.4 : 1.5.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.384-387
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• 2003

The object of the present work is the analysis of head/disk interaction during start/stop and constant speed operation using acoustic emission (AE). The frequency spectrum analysis is performed using the AE signal obtained during the head/disk interaction. The FFT (Fast Fourier Transform) analysis of the AE signals is used to understand the interaction between the AE signal and the state of contact.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.395-401
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• 2013

This study was conducted to evaluate the selective control of creeping bentgrass invaded in Kentucky bluegrass by applying several herbicides and recovery of Kentucky bluegrass by sand injection seeding method. Selective herbicides such as mecoprop, triclopyr-TEA, imazaquin, bentazone and penosulam pyrazosulfuro-ethyl and non-selective herbicides such as glyphosate, paraquat dichloride and glyphsate ammonium oxyflorfen were used. Selective suppression of creeping bentgrass in Kentucky bluegrass was evaluated by turf color, chlorophyll and visual control indexes. Control of creeping bentgrass was most effective with the double dose application of triclopyr-TEA (2 Tri-T) in the selective herbicides and the 1 / 5 dose application of glyphosate ammonium oxyflorfen (1 / 5 GAO) in the non-selective herbicides. Visual control indexes by 2 Tri-T in selective herbicides and 1 / 5 GAOin non-selective herbicides were investigated 6.0 and 7.4, respectively. Treated sites were covered completely in 50 days after seeding Kentucky bluegrass by sand injection method.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.24-33
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• 2000

The effect of particulate contamination on friction and wear between a negative-pressure picoslider / tri-pad nanoslider and laser-textured disk was studied. Particles of different concentration were injected at the head-disk interface consisting of disks with various textures and slider types at different speed. Durability increased and coefficient of friction decreased as the disk speed increased in a contaminated environment. Frictional characteristics and durability in the data zone were better for those of the laser-textured zone. It was also found that durability of head-disk interface (HDI)decreased as the particle concentration increased. The interface durability with a picoslider was better than that with a nanoslider at any condition in a contaminated environment. Based on the test results, mechanisms were proposed to explain the reasons why durability with a picoslider was superior to that with a nanoslider.

• Tribology and Lubricants
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• v.16 no.6
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• pp.469-476
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• 2000

The effect of particulate contamination on the friction and wear between a negative-pressure picoslider/tri-pad nanoslider and laser-textured disk was studied. Particles of different concentration were injected at the head-disk interface consisting of disks with various textures and slider types at different speed. Durability increased and coefficient of friction decreased as the disk speed increased in a contaminated environment. Frictional characteristics and durability in the data Bone were better than those in the laser-textured zone. It was also found that durability of head-disk interface (HDI) decreased as the particle concentration increased. The interface durability with a picoslider was better than that with a nanoslider at any condition in a contaminated environment. Based on the test results, mechanisms were proposed to explain the reasons why durability with a picoslider was superior to that with a nanoslider.

• Journal of Sasang Constitutional Medicine
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• v.28 no.2
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• pp.132-146
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• 2016

Objectives This study's object was to observe the comparative effects of Yangkyuksanhwa-tang, Palmulgunja-tang and Cheongpyesagan-tang on the chronic LT4(levothyroxine) induced hyperthyroidism in rats.Methods Six groups, each of 8 rats in group, were used in this study. Saline and distilled water treated rats are intact control group. Hyperthyroidism was induced by daily subcutaneous LT4 300 μg/kg treatment for 27 days(LT4 control). Since 12th LT4 treatment PTU(propylthiouracil) 10 mg/kg was intraperitoneal injected(PTU group) and aqueous extracts of Yangkyuksanhwa-tang, Palmulgunja-tang and Cheongpyesagan-tang(YS, PG and CS) 500 mg/kg were orally administrated(YS, PG, CS group), once a day for 15 days. The differences in the body, thyroid gland and epididymal fat pad weights, serum T3(tri-iodothyronine), T4(thyroxine), TSH(thyroid-stimulating hormone), thyroid gland and epididymal fat pad histopathology, liver weight, AST(asparte aminotransferase), ALT(alanine aminotransferase) concentrations, hepatic lipid peroxidation, GSH(glutathione), SOD(superoxide dismutase), CAT(catalase) activities, liver histopathology were observed to evaluate effects on hyperthyroidism, liver damages and antioxidant effects.Results As results of LT4 treatment, hyperthyroidism and related liver damages such as lower body, thyroid weights, higher serum T3, T4, AST, ALT levels, thinner follicular lining epithelium in thyroid glands were observed. However, these symptoms were inhibited by oral treatment of YS, PG and CS. As compared with PTU treatment, these herbal prescriptions showed lower overall efficacy on the hyperthyroidism, but YS showed more favorable effects on the hepatic antioxidant defense systems.Conclusions This results suggest that YS, PG and CS favorably control the LT4 induced hyperthyroidism and related liver damages in rats through modulation of the hepatic antioxidative defense systems.

• Tribology and Lubricants
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• v.36 no.1
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• pp.39-46
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• 2020

Air stages are usually applied to precision engineering in sectors such as the semiconductor industry owing to their excellent performance and extremely low friction. Since the productivity of a semiconductor depends on the acceleration and deceleration performance of the air stage, many attempts have been made to improve the speed of the stage. Even during sudden start or stop sequences, the stage should maintain an air film to avoid direct contact between pad and the rail. The purpose of this study is to quantitatively predict the dynamic behavior of the air stage when acceleration and deceleration occur. The air stage is composed of two parts; the stage and the guide-way. The stage transports objects to the guideway, which is supported by an externally pressurized gas bearing. In this study, we use COMSOL Multiphysics to calculate the pressure of the air film between the stage and the guide-way and solve the two-degree-of-freedom equations of motion of the stage. Based on the specified velocity conditions such as the acceleration time and the maximum velocity of stage, we calculate the eccentricity and tilting angle of the stage. The result shows that the stiffness and damping of the gas bearing have non-linear characteristics. Hence, we should consider the operating conditions in the design process of an air stage system because the dynamic behavior of the stage becomes unstable depending on the maximum velocity and the acceleration time.