• 대한기계학회논문집A
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• 제20권3호
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• pp.882-890
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• 1996

Mechanical properties, including Young's modulus, residual stress and rupture strength, of a thermally evaporated gold film have been measured form a blister test. In a theoretical study, the priniple of minimum potential energy and that of virtual work have been applied to the pressurized circular membrane problem, and load-deflection relations have been derived for typical membrane deflection mode of spheroidal shape. In an experimental study, circular gold membranes of 4800 A-thickness and 3.5mm diameter were fabricated by the silicon electropolishing technique. Mecahnical properties of the thin gold films were deduced from the load-deflection curves obtained by the blister test, Young's moduli, obtianed from blister test, have been in the range of 45-70 GPa, while those of bulk gold have been in the range of 78-80 GPa. Residual stresses in the evaporated gold films have been measured as 28-110MPa in tension, The rupture strength of the gold film has turned out to be almost equal to that of dental gold alloy (310-380MPa). It has been demonstrated that the present specimen fabrication method and blister test apparatus have been effective for simultaneous measurement of Young's modulus, residual stress and repture strength of thin solid films. Especially, the electropolishing technique employed here has provided a simple and practical way to fabricate thin membranes in a circular or an arbitrary shape, which could not be obtained by the conventional anisotropic silicon mecromachining technique.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.155-159
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• 2001

In this paper, an on-line dead-time compensation method based on a time delay control approach is presented. The disturbance voltages caused by the dead time are estimated in an on-line manner by the time delay control without any additional circuits and off-line experimental measurements. And the estimated disturbance voltages are fed to voltage references in order to compensate the dead-time effects. The proposed method is applied to a PM synchronous motor drive system and implemented by using software of a digital signal processor (DSP) TMS320C31. Experiments are carried out for this system and the results well demonstrate the effectiveness of the proposed method.

• Journal of Welding and Joining
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• 제33권3호
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• pp.75-80
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• 2015

Self-piercing riveting is an joining method of advanced high strength steels (AHSS) and other dissimilar materials. It has attracted considerable interest from the automotive industry. The SPR has become an interesting alternative joining technique for difficult to weld materials such as steels and aluminium alloys. In this paper, self-piercing rivet and anvil for SPR were designed for the joining conditions with AHSS and aluminium alloy. Various conditions of SPR were simulated for the design of rivets and anvils. The simulated results were in good agreement with experimental ones. As a result, over HV500 rivet is desirable to joint SPFC780 AHSS and aluminum alloy.

• IEIE Transactions on Smart Processing and Computing
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• 제5권4호
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• pp.267-273
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• 2016

Hand posture recognition is an important technique to enable a natural and familiar interface in the human-computer interaction (HCI) field. This paper introduces a hand posture recognition method using a depth camera. Moreover, the hand posture recognition method is incorporated with the Moving Picture Experts Group Rich Media User Interface (MPEG-U) Advanced User Interaction (AUI) Interface (MPEG-U part 2), which can provide a natural interface on a variety of devices. The proposed method initially detects positions and lengths of all fingers opened, and then recognizes the hand posture from the pose of one or two hands, as well as the number of fingers folded when a user presents a gesture representing a pattern in the AUI data format specified in MPEG-U part 2. The AUI interface represents a user's hand posture in the compliant MPEG-U schema structure. Experimental results demonstrate the performance of the hand posture recognition system and verified that the AUI interface is compatible with the MPEG-U standard.

• Journal of Electrical Engineering and information Science
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• 제2권4호
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• pp.86-91
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• 1997

A method of detecting the three phase currents for a voltage-fed pusle width modulated(PWM) inverter is proposed, where only one current sensor is utilized on the dc-link. The proposed method has the constant sampling time by employing he modified space-vector PWM technique which generates the rearranged switching pattern to detect a phase current from ad dc-link current. Experimental results show that eh proposed scheme provides a very good detection method of three phase currents without phase current sensors. This method is very simple and has small detection errors.

• The Korean Journal of Ceramics
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• 제3권3호
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• pp.155-158
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• 1997

Highly oriented diamond films were deposited on a (100) silicon substrate by bias enhanced nucleation technique. Both plan-view and cross-section TEM were applied to study the nucleation and growth mechanism of diamond grains. Randomly oriented polycrystalline diamond grains with internal microtwins were observed at the nucleation stage while defect free regions were retained at the growth stage and were apparently related with the epitaxy of diamond films. From our experimental results, the nucleation and texture formation mechanism of diamond films is discussed.

• Corrosion Science and Technology
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• 제15권2호
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• pp.43-53
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• 2016

In this study, electrochemical impedance spectroscopy (EIS) was used to examine the changes in the electrochemical properties of biodegradable pure magnesium implanted into Sprague-Dawley rats for three days. The in vivo test results were compared with those of the in vitro tests carried out in Hank's, dilute saline and simulated body fluid (SBF) solutions. The in vitro corrosion rates were 20~1700 fold higher, as compared to the in vivo corrosion rates. This discrepancy is caused by biomolecule adsorption on the surface, which prevents the transport of water into the magnesium surface on in vivo testing. Among the in vitro experimental conditions, the corrosion rate in SBF solution had the least difference from the in vivo implanted specimen.

• 제어로봇시스템학회논문지
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• 제6권9호
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• pp.822-830
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• 2000

A conventional advanced control algorithm is proposed in this paper for improved temperature regulation of a TV-glass melting furnace. The TV-Glass melting furnace is a typical MIMO(Multi-Input Multi Output) system which is subject to various thermal disturbances. Because of its complexity, a detailed mathematical model of the furnace is hard to establish. To design a temperature control control system of the furnace, major input-output variables are selected first, and simple FOPDT(First Order Plus Dead Time) models are established based on the physical meaning and experimental process data. Based on the FOPDT models, a multi-loop control system composed of cascade and single loops are designed for effective control of the MIMO system. Practical implementation on the 150 ton/day furnace using the DCS(Distributed Control System) showed that the proposed control technique performs better than manual control.

• Nuclear Engineering and Technology
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• 제51권7호
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• pp.1822-1827
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• 2019

Mechanical responses and failure behaviors of advanced C/C composite tube are very important for structural component design in nuclear reactor. In this study, an experimental investigation was conducted to study mechanical properties of C/C composite tube. Quasi-static compression loading was applied to a type of advanced composite tube to determine the response of the quasi-static load displacement curve during progressive damage. Acoustic emissions (AE) signals were captured and analyzed to characterize the crack formation and crack development. In addition, the crack propagation of the specimens was monitored by imaging technique and failure mode of the specimen was analyzed. FEM is appled to simulate the stress distribution. Results show that advanced C/C composite tube exhibits considerable energy absorption capability and stability in load-carrying capacity.

• Asian-Australasian Journal of Animal Sciences
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• 제24권6호
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• pp.810-817
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• 2011

A feeding trial was conducted to study the effect of tannin rich Pakar (Ficus infectoria) leaves on microbial profile, rumen fermentation and nutrient utilization in goats. Eight goats divided in two groups were fed pakar leaves (experimental group) and green oats (control group) as sole roughage source along with a fixed quantity of concentrate mixture for a period of 3 months. Two metabolic trials of six days duration were conducted after 30 and 90 days of experimental feeding. The dry matter intake was significantly higher (p<0.05) and digestibility's of DM, OM, CP, EE, NDF and ADF were reduced in experimental as compared with the control group. The TDN intake was similar (236.52 vs. 240.39 g/d) in both the groups. All the animals were in positive nitrogen balance. The concentration of ammonia nitrogen, TVFA, lactic acid and activities of xylanase and protease were reduced in pakar leaves fed goats. The rumen microbial profile as obtained by MPN technique showed no change in total bacterial population but total fungi and cellulolytic bacteria were reduced (p<0.05), whereas, tannin degrading/tolerant bacteria increased with the feeding of pakar leaves. Real time PCR data revealed a decrease in Ruminococcus flavefaciens, an increase in methanogens and no change in the Fibrobacter succinogenes population by feeding of pakar leaves.