• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.7
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• pp.635-641
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• 2005

This study experimented to understand the effects of transporting ice slurry through elbow and inclined tube. And at this experiment it used propylene glycol-water solution and a diameter of about 2mm ice particle. The experiments were carried out under various conditions, with velocity of water solution at the entry ranging from 1.0 to 3.5 w/s and elbows and inclined tubes of 4 kinds angle with $30^{\circ},\;45^{\circ},\;90^{\circ}\;and\;180^{\circ}$. The pressure drop between the tube entry and exit were measured. According to angle of bending, the highest pressure drop was measured at $30^{\circ}$ elbow and the lowest pressure drop was measured at $90^{\circ}$ elbow, and there are only a little differences of pressure drop between $45^{\circ}$ elbow and $180^{\circ}$ elbow. According to angle of inclined tube, the highest pressure drop was measured at $90^{\circ}$ inclined tube and the pressure drop at $45^{\circ},\;30^{\circ},\;180^{\circ}$ inclined tubes were lower successively. The lowest pressure drop in elbows and inclined tubes was measured at velocity of $2.0\~2.5$ m/s and concentration of $10\;wt\%$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.193-199
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• 2009

In this paper, impedance analysis of a differential pall having 2 drop configuration is performed using the reflection theory and verified by circuit simulator (Ansoft designer). Through the impedance analysis, it was possible to understand the signal transmission at a differential pall, and an optimized 2 drop design technique of a differential pair could be developed. When compared with the conventional design, the proposed design shows a good signal integrity and has much less design restrictions.

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.217-229
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• 2003

The purpose of this study was to present the basic data on improving the skills for 3 junior high school national badminton players in clear and drop motion through the 3-dimensional image analysis. Therefore, the results of this study are as follows: 1. In the duration times per phase, subject C relatively showed a similar time between clear and drop motion. Accordingly, C took a more effective motion than A and B. 2. In the velocities of racket head, subject A and C showed similar changes relatively. However, in case of subject B, the velocity was decreased before back swing(E2) and increased until impact(E3). 3. Regardless of clear and drop motion, the changing phases of joint angle for wrist and elbow showed similar changes comparatively. 4. In the angles of upper body, clear motion was average 85.0 degree and drop one was average 80.7 degree during the impact(E3). Hence, it showed that drop motion hit the ball bowing the upper body more than clear one. 5. In the angles of racket head, clear motion was average 87.7 degree and drop one was average 85.6 degree during the impact(E3). Consequently, drop motion was impacted forward more than clear one.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2007.04a
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• pp.37-47
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• 2007

Factor : Structure Metal pad & SMO size Board level TC test : - Large SMO size better Board level Drop test : - Large SMO size better Factor : Structure Substrate thickness Board level TC test : - Thick substrate better Board level Drop test : - Substrate thickness is not a significant factor for drop test Factor : Material Solder alloy Board level TC test : - Not so big differences over Pb-free solder and NiAu, OSP finish Board level Drop test : - Ni/Au+SAC105, CuOSP+LF35 are better Factor : Material Pad finish Board level TC test : - NiAu/NiAu is best Board livel Drop test : - CuOSP is best Factor : Material Underfill Board level TC test - Several underfills (reworkable) are passed TCG x500 cycles Board level Drop test : - Underfill lots have better performance than non-underfill lots Factor : Process Multiple reflow Board level TC test : - Multiple reflow is not a significant actor for TC test Board level Drop test : N/A Factor : Process Peak temp Board level TC test : - Higher peak temperature is worse than STD Board level Drop test : N/A Factor : Process Stack method Board level TC test : - No big difference between pre-stack and SMT stack Board level Drop test : - Flux dipping is better than paste dipping but failure rate is more faster

• The KSFM Journal of Fluid Machinery
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• v.10 no.4
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• pp.55-60
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• 2007

This paper describes an evaluation method of pressure drop in a circular pipe of waste collection piping system. Accurate pressure drop in a piping system is very important to determine the capacity of turbo blower, which is one of the main elements in the system. Three-dimensional Navier-Stokes analysis is introduced to analyze the pressure drop in the piping system. Organic waste is selected and modeled using the result of site survey performed in an apartment area. Evaluation method of pressure drop used In the present numerical simulation is performed in the shortened pipe line prior to the calculation of the real system. Throughout the numerical simulation, pressure drop in a waste pipe is obtained and compared to the value determined by analytical method. The pressure drop obtained by numerical simulation has a good agreement with that of the analytic method. It is noted that present evaluation method is effective to determine a pressure drop in the piping system. Detailed flow characteristics inside the pipe line are also analyzed and discussed.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.48-48
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• 2009

Conventionally in pulsed gas metal arc welding (GMAW-P), drop transfer is analyzed with simplest square pulse waveform. While the pulse current is described by four parameters (peak current magnitude and time plus base current magnitude and time), it deviates the real pulse shape. Real pulse can be better idealized by the trapezoidal pulse waveform described by two additional parameters, i.e., current rise and fall rate (dI/dt). Power source response rate is described by these parameters. In this work, the effect of these parameters on drop transfer is predicted by the force displacement model (FDM). While peak current has significant effects on drop detachment, drop transfer is also influenced by the current rise rate. Predictions indicate that the current rise rate can have considerable effects on the size of the detached drop if other pulse parameters are kept constant. FDM is applied to determine peak time for one drop one pulse condition (ODOP) when rests of the pulse parameters are given. The predicted range of ODOP shows good agreement with experimental data.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.10
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• pp.51-56
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• 2000

An all fiber coupler-type add/drop filter has been fabricated by writing a Bragg grating in the coupling region of a fused fiber coupler. The fused fiber coupler with 99.8% coupling ratio and 74/m coupling coefficient was used for the add/drop filter. The add/drop filter shows 99% reflectivity and 83% drop efficiency at the operating wavelength of 1536.2nm.

• Journal of International Academy of Physical Therapy Research
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• v.11 no.1
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• pp.1992-1998
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• 2020

Background: The foot drop stimulator is designed to improve the walking ability of foot drop in patients after stroke, however, studies on clinical effects are still lacking. Objective: To investigate the effect of a foot drop stimulator on the walking and balancing abilities of foot drop patients after a stroke. Design: One-Group (Pretest-Posttest) Design. Methods: All subjects walked in all three conditions: foot drop stimulator (FDS) ankle foot orthosis (AFO) and barefoot. Primary outcome measures were assessed for walking and balance using a 10-m walking test (10MWT) and a timed up and go test (TUG). Secondary outcome measures consisted of a brief user interview, and the patients recorded the advantages and disadvantages of each condition. Results: FDS, AFO, and barefoot conditions showed a statistically significant difference in 10MWT and TUG (P<.001) as a result of comparing three conditions. FDS and AFO were significantly different from the barefoot condition as post-hoc results; however, there was no significant difference between the two conditions (P>.05). Conclusion: In this study, the foot drop stimulator contributed to improving the balance ability, and the walking ability was similar to the effect of the ankle-foot orthosis.

• The Journal of Korean Physical Therapy
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• v.31 no.4
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• pp.222-227
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• 2019

Purpose: This study examined the influence of longitudinal arch on the strength and muscle activity of the abductor hallucis in the standing position in subjects with and without navicular drop signs. Methods: A sample of 34 subjects with and without navicular drop signs between 22 and 28 years of age were enrolled in this study. The strength and muscle activity of the abductor hallucis was measured using a tensiometer. The Smart KEMA System and electromyography device was used on the subjects with and without navicular drop signs. Two groups were classified using the navicular drop test to identify the longitudinal arch of the foot. The strength of the abductor hallucis was evaluated in standing, both with and without an external arch support condition. The two-way mixed ANOVA was used. The level of statistical significance was set to ${\alpha}=0.05$. Results: The strength and muscle activity of the abductor hallucis in standing was significantly higher with external arch support than that without the external arch support in the group with navicular drop signs. There was no significant difference in the abductor hallucis strength and muscle activity with and without external arch support in the subjects without navicular drop signs. Conclusions: The strength and muscle activity of the abductor hallucis in standing can be influenced by the external arch support in the group with navicular drop signs. The strength measurement of the abductor hallucis in standing should be separately performed in conditions with and without longitudinal arch of foot.

• Journal of Biosystems Engineering
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• v.26 no.5
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• pp.461-468
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• 2001

Impact between fruits and other materials is a major cause of product damage in harvesting and handling systems. The oriental pears are more susceptible to bruising than other fruits such as European pears and apples, and are required more careful handling. The interest in the handling of the pears for the processing systems has raised the question of the allowable drop height to which pears can be dropped without causing objectionable damage. Drop tests on pears were conducted using an impact device developed by authors to estimate the allowable drop height without bruising. The impact device was constructed to hold in a selected orientation and to release a fruit by vacuum for dropping on to a force transducer. The drop height was adjustable for zero to 60 cm to achieve the desired distance between the bottom of the fruits and the top of the impact force transducer. The transducer was secured to 150 kg$\sub$f/ concrete block. The transducer signal was sampled every 0.17 ms with a strain gage measurement board in the micro computer where it was digitaly stored for later analysis. The selected sample fruit was Niitaka cultivar of pears which is one of the most promising fruit for export in Korea. The pears were harvested during the 1998 harvest season from an orchard in Daejeon. The sample fruit was selected from two groups which were stored for 3 months and 5 months respectively by the method of current commercial practice. The pears were allowed to stabilize at environmental condition(18$^{\circ}C$, 65% rh) of the experimental room. One hundred fifty six pears were tested from the heights of 5, 7.5. 10 and 12.5 cm while measurement were made of impact peak force, contact time, time to peak force, dwell time, pear diameter and mass. The bioyield strength and modulus of elasticity were measured using UTM immediately after each drop test. The allowable drop height was estimated on the base of bioyield strength of the pears in two ways. One was assumed the peak force during impact test increasing linearly with time, and the other was based on the actual drop test results. The computer program was developed for measuring the impact characteristics of the pears and analyzing the data obtained in the study. The peak force increased while contact times decreased with increasing drop height and contact times of the sample from the hard tissue group. The allowable drop height increased with increasing bioyield strength and contact times, and also varied with Poisson\`s ratio, mass and equilibrium radius of the pears. The allowable drop height calculated by a theoretical method was in the range from 1 to 4 cm, meanwhile, the estimated drop height considering the result of the impact test was in the range from 1 to 6 cm. Since the physical properties of fruits affected significantly the allowable drop height, the physical properties of the fruits should be considered when estimating the allowable drop height.