• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.2
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• pp.12-20
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• 2000

The numerical analysis, including chemical reaction of an entire ramjet engine is studied to understand the ignition transient mechanism and the dynamic characteristics of the Integrated Rocket Ramjet System comprehensively. Details of how a subsonic combustion environment is established from the supersonic ram air after removal of the inlet port cover, are examined during the ignition transient. Various physical processes are investigated systemically, including ignition, flame propagation, flame dynamics, and vorticity evolution.

• Laser Solutions
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• v.4 no.2
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• pp.39-45
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• 2001

This paper introduces a cleaning process for removing submicron-sized particles from NiP hard disk substrates by the liquid-assisted laser cleaning technique. Measurements of cleaning Performance and time-resolved optical diagnostics are Performed to analyze the physical mechanism of contaminant removal. The results reveal that nanosecond laser pulses are effective for removing the contaminants regardless of the wavelength and that a thermal mechanism involving explosive vaporization of liquid dominates the cleaning process.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.12
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• pp.88-97
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• 1993

Electrostatic Discharge(ESD) is one of the major reliability, issues for today's VLSI production. Since the gate oxide with a thickness of 100~300$\AA$ is vulnerable to several thousand volt of ESD surge, it is necessary to control the ESD events and design an efficient protection circuit. In this paper, physical mechanism of the catastrophic ESD damage is investigated by transient analysis based upon Human Body Model(HBM). Using two-dimensional electrothermal simulator, we study the failure mechanism of the output protection devices by ESD and discuss the design issues for the optimun protection network.

• Korean Journal of Cognitive Science
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• v.20 no.4
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• pp.481-506
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• 2009

The purpose of the present research was to examine whether the attention mechanism employs physical or represented location of the cue and target. To achieve this, we have employed the paradigm of facilitation of response as well as inhibition of return. In the experiments, valid and invalid conditions were defined by the position consistency of the cue and the target in the aspect of either physical or represented location. We used auditory cue and visual target in Experiment 1 while visual cue and auditory target in Experiment 2. As a results, in Experiment 1, effect of facilitation of response in valid condition was found when the valid/invalid conditions were defined in the aspect of represented location. In Experiment 2, effect of facilitation of response in valid condition was found when the valid/invalid conditions were defined in the aspect of represented location. In all the other conditions, no effect was found when the conditions were defined in the aspect of physical location. No effects of inhibition of return were found in Experiment 2. These results imply the possibility that attention mechanism operates based on objects' represented location rather than on their physical location. More importantly, the present research suggests that it is necessary to separate represented location from physical location of the target and the cue in the experiment of facilitation of response and inhibition of return in the future.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.2
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• pp.239-244
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• 2017

We experimentally investigate the physical mechanism for asymmetrical degradation in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) under simultaneous gate and drain bias stresses. The transfer curves exhibit an asymmetrical negative shift after the application of gate-to-source ($V_{GS}$) and drain-to-source ($V_{DS}$) bias stresses of ($V_{GS}=24V$, $V_{DS}=15.9V$) and ($V_{GS}=22V$, $V_{DS}=20V$), but the asymmetrical degradation is more significant after the bias stress ($V_{GS}$, $V_{DS}$) of (22 V, 20 V) nevertheless the vertical electric field at the source is higher under the bias stress ($V_{GS}$, $V_{DS}$) of (24 V, 15.9 V) than (22 V, 20 V). By using the modified external load resistance method, we extract the source contact resistance ($R_S$) and the voltage drop at $R_S$ ($V_{S,\;drop}$) in the fabricated a-IGZO TFT under both bias stresses. A significantly higher RS and $V_{S,\;drop}$ are extracted under the bias stress ($V_{GS}$, $V_{DS}$) of (22 V, 20V) than (24 V, 15.9 V), which implies that the high horizontal electric field across the source contact due to the large voltage drop at the reverse biased Schottky junction is the dominant physical mechanism causing the asymmetrical degradation of a-IGZO TFTs under simultaneous gate and drain bias stresses.

• The KIPS Transactions:PartA
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• v.16A no.3
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• pp.199-208
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• 2009

Recently, there are many embedded system prototyping tools for helping embedded system designers to trial their product before it releases to the market. A prototype is very important for early embedded system design to grasp the desire functions, to get a good performance, to create delightful user interface, and to increase the valuable of the product. Prototyping tools can be classified by three categories: Physical, Virtual and Modeling prototyping. The integration of these prototyping tools becomes valuable for speed up time-to-market and for decrease design cost when design embedded system. The problem comes up because these tools sometime do not provide an instrument for communicating each other. In this paper, we propose a flexible and reusable mechanism for integrate these tools base on JavaBeans and ActiveX technology. We show how this mechanism can be employed in various prototyping tools.

• IMMUNE NETWORK
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• v.5 no.4
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• pp.252-257
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• 2005

Background: This study was designed to investigate the effect of exercise training on defense mechanism of chronic degenerative disease, aging, and memory impairments of senescence-accelerated mouse (SAM)P8 under the hypothesis that "Senile dementia may be prevented by regular exercises". Methods: To evaluate the effects of exercise training on the defense mechanism of aging and memory impairment, SAMP8 were divided into two groups, the control group and exercise training groups. the exercise training group were performed with low $(\dot{V}O_2max\;25{\sim}33%)$, middle ($\dot{V}O_2max$ 50%) and high $(\dot{V}O_2max\;66{\sim}75%)$ intensity exercise. All SAMP8 mice were fed experimental diet ad libitum until 4, 8 months, and dead period. Results: Median lifespan in middle exercise group resulted in a significantly increased (23.5% and 18.7%, respectively), whereas these lifespan in high exercise group resulted in an unexpectedly decreased (13.5% and 12.1%, respectively) compared with control group. Body fat levels in 4 and 8 months of age were significantly decreased 43% to 51% in middle exercise group, whereas were remarkably deceased to 57% in high exercise group compared with control group. It is believed that extended median and maximum lifespan may be effected by calory restriction through the exercise training. Acetylcholine (ACh) levels were significantly increased 6.7% and 8.5% in middle and high exercise groups, and also choline acetyltransfease (ChAT) activities were significantly increased 10.3% and 11.9% in middle and high exercise groups. Conclusion: These results suggest that proper and regular exercises such as middle group ($\dot{V}O_2max$ 50%) may play an effective role in attenuating an oxygen radicals and may play an important role in improving a learning and memory impairments of senile dementia.

• Physical Therapy Korea
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• v.8 no.4
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• pp.81-89
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• 2001

There are two independent mechanisms to control the segmental reflex gain in humans during gait. They are presynaptic inhibition and homosynaptic depression. Through the mechanism of the presynaptic inhibition, the muscle spindle afferent feedback can be properly gated during eccentric phase of gait. The modulation of the presynaptic inhibition is reflected in the level of H-reflex at a constant EMG level. During the eccentric muscle activation presynaptic inhibition should increase to account for the lower amplitude level of H-reflex at a constant level of EMG. Homosynaptic depression is another mechanism responsible for regulating the effectiveness of the muscle spindle afferent feedback. Both the presynaptic inhibition and the monosynaptic depression are responsible for modulating reflex gain during gait initiation. Reflex modulation is influenced not only as a passive consequence of the alpha motor neuron excitation level, but also through supraspinal mechanisms. Spastic paretic patients show the impaired soleus H-reflex modulation either during the initial stance phase, or during the swing phase. This abnormal modulatory mechanism can partially and artificially be restored by the application of peripheral stimulus to the sole of the foot, provided that the segmental circuitry remains functional.

• Korean Journal of Applied Biomechanics
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• v.20 no.1
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• pp.67-73
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• 2010

The purpose of this study was to compare the differences in kinematic and kinetic parameters of the ankle and knee joint according to three landing direction(central, left, right). Fifteen collegiate male athletes(age: $22.7{\pm}3.5$ years, height: $174.9{\pm}7.1\;cm$, weight: $69.4{\pm}6.7\;kg$) with the right leg as dominant were chosen. The subjects performed series of drop landings in three directions. In terms of the three different landing directions, plantar flexion was the greatest during the central drop landings. For each initial contact of the landing direction, plantar flexion of the ankle was greatest at the central drop landing, inversion of the ankle was greatest at the right landing and valgus of the knee was greatest at the left drop landing. Regarding the peak force, the greatest was at the 1st peak force during the central drop landing. For the time-span of the 2nd peak force and the 2-1 peak force, both right sides resulted as the greatest. Therefore, with the appropriate training in landing techniques and developing neuromuscular training for proprioception by taking the injury mechanisms on ankle and knee during drop landings into account, it will assist in preventing such injuries.

• Geomechanics and Engineering
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• v.25 no.3
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• pp.179-194
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• 2021

In this paper, to study the stability of surrounding rock during roadway excavation in different rock mass structures, the physical model test for roadway excavation process in three types of intact rock mass, layered rock mass and massive rock mass were carried out by using the self-developed two-dimensional simulation testing system of complex underground engineering. Firstly, based on the engineering background of a deep mine in eastern China, the similar materials of the most appropriate ratio in line with the similarity theory were tested, compared and determined. Then, the physical models of four different schemes with 1000 mm (height) × 1000 mm (length) × 250 mm (width) were constructed. Finally, the roadway excavation was carried out after applying boundary conditions to the physical model by the simulation testing system. The results indicate that the supporting effect of rockbolts has a great influence on the shallow surrounding rock, and the rock mass structure can affect the overall stability of the surrounding rock. Furthermore, the failure mechanism and bearing capacity of surrounding rock were further discussed from the comparison of stress evolution characteristics, distribution of stress arch, and failure modes in different schemes.