• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.187-190
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• 2014

An experimental study on downwardly and upwardly spreading flames over slanted electrical wire, which is insulated by Polyethylene(PE), was conducted with applied AC electric field. The result showed that downwardly and upwardly spreading flames with angle of inclination leaned toward burnt side and unburned side, respectively. With applied AC electric fields, size of downwardly spreading flame decreased slightly and that of upwardly spreading flame increased significantly. Flame spread rate showed various trends in terms of inclination, applied voltage and frequency.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.363-365
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• 2014

An experimental study on effect of AC electric field on upwardly spreading flame over electrical wire, which is insulated by Polyethylene(PE), was conducted. The result showed that upwardly spreading flame leaned toward unburned side with angle of inclination. With applied electric field, size of upwardly spreading flame increased significantly. Flame spread rate showed various trends with inclination, applied voltage and frequency.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.49-56
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• 1999

The effects of the internal flow in a D.I. Diesel injection nozzle on the atomization of a spray were analyzed experimentally. Flow visualization studies were made using a transparent acrylic model nozzle as a diesel nozzle . Water instead of disel fuel was used as the injection liquid. The geometry of the model nozzle was scaled up 10 times of the actual nozzle and the injection pressure for the model nozzle was adjusted so as to achieve a Reynolds number at the discharge hole that was the same as the actual nozzle. Experimental results show that when the needle lift was small, the high turbulence in the sac chamber generated by the high velocity seat flow made the spread angle of the spray plume large. Cavitation, which arose from the sac chamber, makes the spread angle of the spray plume large but the discharge coefficient small.

• Steel and Composite Structures
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• v.46 no.1
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• pp.53-73
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• 2023

Man-made structure materials like concrete usually contain inclusions. These inclusions affect the mechanical properties of concrete. In this investigation, the influence of inclusion length and inclination angle on three-dimensional failure mechanism of concrete under uniaxial compression were performed using experimental test and numerical simulation. Approach of acoustic emission were jointly used to analyze the damage and fracture process. Besides, by combining the stress-strain behavior, quantitative determination of the thresholds of crack stress were done. concrete specimens with dimensions of 120 mm × 150 mm × 100 mm were provided. One and two holes filled by gypsum are incorporated in concrete samples. To build the inclusion, firstly cylinder steel tube was pre-inserting into the concrete and removing them after the initial hardening of the specimen. Secondly, the gypsum was poured into the holes. Tensile strengths of concrete and gypsum were 2.45 MPa and 1.5 MPa, respectively. The angle bertween inclusions and axial loadind ary from 0 to 90 with increases of 30. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Diameter of the hole was 20 mm. Entirely 20 various models were examined under uniaxial test. Simultaneous with experimental tests, numerical simulation (Particle flow code in two dimension) were carried out on the numerical models containing the inclusions. The numerical model were calibrated firstly by experimental outputs and then failure behavior of models containing inclusions have been investigated. The angle bertween inclusions and axial loadind vary from 0 to 90 with increases of 15. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Entirely 32 various models were examined under uniaxial test. Loading rate was 0.05 mm/sec. The results indicated that when inclusion has occupied 100% of sample thickness, two tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusion has occupied 75% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusions have occupied 50% and 25% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. Also the inclusion was failed by one tensile crack. The compressive strength of samples decease with the decreases of the inclusions length, and inclusion angle had some effects on that. Failure of concrete is mostly due to the tensile crack. The behavior of crack, was affected by the inclusion length and inclusion number.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.454-459
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• 1997

The good features of a switched reluctance motor(SRM) are appreciated by the appliance manufactures. And it is spread into a commercial and industries market. The few disadvantage of the motor is higher torque ripple and noise. This paper proposes an instantaneous torque control scheme to control a speed precisely. It adapts phase-locked loop (PLL) technique to control speed precisely. In this control scheme, the phase detector signal of the PLL regulates the switching dwell angle flexibly and the loop filter's signal controls adaptively the instantaneous switching voltage. Experimental results show that drive performance is good with low torque ripple.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.1
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• pp.29-39
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• 1988

Plastically deformed layer beneath metal surface machined by orthogonal cutting was evaluated in terms of residual stress, microvickers hardness, side spread, and the side strain. An attempt was made to predict the depth of layer according to machining conditions particularly tool geometry and the shear plane angle. In this paper, we employed two models concerning the sliplines. The exact model was validated by comparision of computed and measured tool force and its angle, and the model offers an upper boundary of the deformed layer to be in good agreement with the experiment.

• Physical Therapy Korea
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• v.23 no.3
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• pp.21-28
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• 2016

Background: The toe-spread-out (TSO) exercise has been introduced as a strengthening exercise for the abductor hallucis muscle in subjects with hallux valgus. Visual biofeedback using ultrasound imaging during exercise, may increase the ability to selectively contract the abductor hallucis muscle, compared with exercise alone. Objects: The aim of this study was to investigate the effects of ultrasound imaging visual feedback during the TSO exercise with respect to its influence on the angle of the first metatarsophalangeal joint (1st MPJ) and the cross-sectional area (CSA) of the abductor hallucis muscle in subjects with hallux valgus. Methods: Twenty-five healthy young subjects with a mean average age of 22.5 years, and a standard deviation of 2.3 years, were recruited for this study. Hallux valgus was defined as an angles greater than $15^{\circ}$ angle of 1st MPJ. Goniometric measurement was used to determine the angle of 1st MPJ. In addition, an ultrasound system was used to collect the CSA of the abductor hallucis muscle in each foot. The angle of the 1st MPJ and CSA of the abductor hallucis were measured in three positions; the resting position, during TSO exercise, and during TSO exercise in conjunction with real-time ultrasound imaging feedback. All data analyzed using a repeated analysis of variance with Bonferroni correction in order to compare the dependent variables in all three positions. Statistical level of significance was set up as p<.05. Results: The angle of the 1st MPJ was noted to be significantly reduced and the CSA of the abductor hallucis to be significantly greater during TSO exercise used in conjunction with ultrasound imaging visual feedback, compared to when the values were recorded during TSO exercise alone (p<.05). Conclusion: Based on these findings, it can be concluded that the application of ultrasound imaging visual feedback during TSO exercise is more effective in contracting selectively the abductor hallucis than the use of exercise alone.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.2
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• pp.122-128
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• 2007

GIS is used much research for efficient forest fire management and forecasting and slope has been known as high-leverage thing in spread of forest fire specially. Various algorithms are used usually to calculate slope angle of topography from DEM(Digital elevation model). However, because spread speed of forest fire is different according to uphill slope and downhill slope, it need new slope calculation algorithm. Therefore, developed slope calculation algorithm can reflect uphill slope and forest fire spread speed of looking downhill slope.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.11
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• pp.81-86
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• 2004

Hybrid beamformer composed of Direction-of-Arrival (DOA) based scheme followed by Maximal Ratio Combining (MRC) is proposed to overcome the degradation due to inaccurate channel estimation caused by insufficient pilot power, which happens in conventional Single-Input Multiple-Output (SIMO) Code Division Multiple Access (CDMA) reverse link. The proposed scheme could provide more accurate channel estimation and interference reduction at the expense of diversity gam in the spatially correlated SIMO channel. As a result, hybrid scheme outperforms conventional MRC beamformer for six or more antennas in the channel environment, in which Angle-of-Spread (AOS) is within 30$^{\circ}$.

• The Korean Journal of Pain
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• v.26 no.4
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• pp.396-400
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• 2013

Conventional transcrural CPB via the "walking off" the vertebra technique may injure vital organs while attempting to proximally spread injectate around the celiac plexus. Therefore, we attempted the CT-simulated fluoroscopy-guided transdiscal approach to carry out transcrural CPB in a safer manner, spreading the injectate more completely and closely within the celiac plexus area. A 54-year-old male patient with pancreatic cancer suffered from severe epigastric pain. The conventional transcrural approach was simulated, but the needle pathway was impeded by the kidney on the right side and by the aorta on the left side. After simulating the transdiscal pathway through the T11-12 intervertebral disc, we predetermined the optimal insertion point (3.6 cm from the midline), insertion angle (18 degrees), and advancement plane, as well as the proper depth. With the transdiscal approach, we successfully performed transcrural CPB within a narrow angle, and the bilateral approach was not necessary as we were able to achieve the bilateral spread of the injectate with the single approach.