• Applied Science and Convergence Technology
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• v.23 no.2
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• pp.97-102
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• 2014

A vacuum chamber for a commercial atomic force microscope (AFM) is designed and fabricated. Only minimal modifications were made to an existing microscope in an effort to work in a vacuum environment, while most of the available AFM functionalities were kept intact. The optical alignment needed for proper AFM operations including a SLD (superluminescent diode) and a photodiode can be made externally without breaking the vacuum. A vacuum level of $5{\times}10^{-3}$ torr was achieved with a mechanical pump. An enhancement of the quality factor was observed along with a shift in the resonance frequency of a non-contact-mode cantilever in a vacuum. Topographical data of a calibration sample were also obtained in air and in a low vacuum using the non-contact mode and the results were compared.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.197-204
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• 2005

In this study, ground reaction force(GRF), absolute symmetry index(ASI) and coefficient of variation(CV) of fixed, single-axis and multi-axis prosthetic ankle assemblies were investigated to show the biomechanical evaluation for above knee amputees. In the experiments, 37 normal male volunteers, two male and two female AK amputees were tested with fixed, single-axis and multi-axis prosthetic ankle assembly. A gait analysis was carried out to derive the ratio of GRF to weight as the percentage of total stance phase for ten points. The results showed that fixed-axis ankle was superior to the other two ankle assemblies for the characteristic of forwarding and breaking forces. Multi-axis ankle was relatively superior to the other two ankle assemblies for gait balancing and movement of the center for mass. single-axis ankle was relatively superior to the other two ankle assemblies for CV and ASI of GRF.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.2
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• pp.47-57
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• 1990

In-process recognition of the cutting states is one of the very important technologies to increase the reliability of mordern machining process. In this study, practical methods which use the dynamic component of the cutting force are proposed to recognize cutting states (i.e. chip formation, tool wear, surface roughness) in turning process. The signal processing method developed in this study is efficient to measure the maximum amplitude of the dynamic component of cutting force which is closely related to the chip breaking (cut-off frequency : 80-500 Hz) and the approximately natural frequency of cutting tool (5, 000-8, 000 Hz). It can be clarified that the monitoring of the maximum apmlitude in the dynamic component of the cutting force enables the state of chip formation which chips can be easily hancled and the inferiority state of the machined surface to be recognized. The microcomputer in-process tool wear monitor- ing system introduced in this paper can detect the determination of the time to change cutting tool.

• Food Science of Animal Resources
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• v.27 no.1
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• pp.35-41
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• 2007

This study was conducted to determine the effect of pH adjustment and addition of sodium chloride (NaCl) on quality characteristics of pork leg surimi. The pork leg surimi was manufactured with one of following pH 3.0 or pH 11.0 adjustment and contained 2% NaCl or not; C (Alaska pollack surimi, two times washing, 0% NaCl), T1 (pork leg surimi pH 3.0 adjustment, 0% NaCl), T2 (pork leg surimi, pH 3.0 adjustment, 2% NaCl), T3 (pork leg surimi, pH 11.0 adjustment 0% NaCl), T4 (pork leg surimi, pH 11.0 adjustment, 2% NaCl). The $L^*$ and W values was increased with increasing of pH value, but the $a^*$ and $b^*$ values lower. The W values were higher (p<0.05) as addition of NaCl, but $a^*$ and $b^*$ values were lower. In textural properties, the cohesiveness was increased with increasing of pH value, however with the exception of springiness all traits were higher (p<0.05) as addition of NaCl. The breaking force and gel strength was increased with increasing of pH value. The breaking force, gel strength and breaking force u deformation were higher as addition of NaCl, but shear force lower. In sensory evaluation, the tenderness was increased with increasing of pH value and all traits of sensory evaluation also were higher (p<0.05) as addition of NaCl. There were no differences in interaction of pH adjustment and without or with NaCl on color, textural properties, breaking force, deformation, gel strength, shear force and sensory evaluation of pork leg surimi. The color, textural and physical characteristics and sensory evaluation ot T2 and T4 were similar to treatment C. Therefore, the pH 11.0 and 2% NaCl addition on process of manufacture of pork leg surimi would be recommended.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.154-160
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• 2004

Hydraulic breaker of excavator has been used for the destruction and disassembling of buildings, crashing road pavement, breaking rocks at quaky and etc. The performance of breakers is evaluated their own destructive force and the number of impact by input hydraulic flow rate and pressure on the operating conditions. Because hydraulic breakers generate high impact energy, the accurate measurement of the impact force has been facing a technical challenge. In this study, the hydraulic pressure transducer system was developed based on the characteristics of pressure variation in closed vessel fur testing the impact energy. The hydraulic pressure transducer system is consisted with a hydraulic cylinder, main base, pressure & temperature sensors, LVDT, data acquisition system and etc. The developed hydraulic pressure transducer system was applied to measure the impact energy for hydraulic breaker. The measured impact force was 438.8 kgf.m within the designed impact force bounds. The developed hydraulic pressure transducer system as a simple tester could be applied to measure the impact force and the number of impact.

• Korean Journal of Breeding Science
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• v.43 no.4
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• pp.311-317
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• 2011

This experiment was conducted to give basic information to sprout-soybean breeding and automated sprout production by investigating the effect of seed size on the sprout growth and texture. Twenty cultivars and lines including large and medium soybean, small interspecific cultivars and extra-small wild soybean lines were used. Seeds were cultured for 4 days using small sprout-culturing kits. Hypocotyl length of large Hwanggeumkong, small Pungsannamulkong and Soyoung were longer and wild soybean lines were shorter than other cultivars. Fresh sprout weight and growth rate per unit dry seed weight of wild soybean lines ware increased dramatically and more than other cultivars between 48 to 72 hours after culture. Not only the increasing rate but sprout yield ratio to used dry seed weight showed the negative relationship pattern with seed size. The hardness of hypocotyl in Jangyeubkong, mastication in Taekwang, and cutting force in Eunhakong were the highest as 3,505 g, 1,650 g, and 133 g respectively, and texture values of these traits in wild soybean YWS516 were the lowest. Cutting force of soybean hypocotyl showed the positive relationship pattern with seed size. Breaking force of hypocotyl in large Jangyeobkong was the highest as 83.5g and wild soybean lines were the lowest showing the same pattern as other textural characters.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.419-422
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• 2005

Global bifurcations and chaos in modal interactions of an imperfect circular plate with one-to-one internal resonance are investigated. The case of primary resonance, in which an excitation frequency is near natural frequencies, is considered. The damping force is not included in the analysis. The renormalization-group technique for KAM tori is used to obtain the criteria for large-scale stochasticity in the system.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1592-1595
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• 1998

The rock fragmentation system with a capacitor bank, switching device, cable and blasting electrode are described. Utilization of the chemical energy from the electrolyte and the pseudospark with a large current capacity suggested the commercialization possibility of the rock fragmentation system. The vibration and noise level of the pulsed blasting is acceptable in the most ground breaking. And also the electromagnetic force produced by the inductor is introduced for the rock fragmentation.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.411-416
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• 2002

The strength evaluation of a wheel is becoming very important due to the high speed of railway system and the reduction of wheel weight. Therefore, in this study, the influence of thermal stress at tread breaking in Korean High Speed Train wheel was investigated using FEM. During FEM analysis, the mechanical load or wheel-rail contract load and braking load were considered. When 300% of the block force was applied, the maximum von Mises stress of 61.0 ㎫ was found at the outside plate around 400mm far away from the wheel center.

• Journal of the Semiconductor & Display Technology
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• v.3 no.3
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• pp.27-29
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• 2004

The responses of hypothetical silicon nanotubes under torsion have been investigated using an atomistic simulation based on the Tersoff potential. A torque, proportional to the deformation within Hooke's law, resulted in the ribbon-like flattened shapes and eventually led to a breaking of hypothetical silicon nanotubes. Each shape change of hypothetical silicon nanotubes corresponded to an abrupt energy change and a singularity in the strain energy curve as a function of the external tangential force, torque, or twisted angle. The dynamics of silicon nanotubes under torsion can be modelled in the continuum elasticity theory.