• 기술발표회
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• s.2006
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• pp.162-171
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• 2006

Segmental Grid Retaining Wall is one of the segmental grid retaining walls using headers and stretchers to establish the framework of the wall In this method, grids formed by the intersection of headers and stretchers are generally filled with the gravel to maintain the weight of the wall Therefore, the construction can be carried out with higher speed and much economically when compared with the concrete retaining wall Furthermore, it has high drain capacity, and environmentally friendly aspects also have been pointed out because the possibility of the planting at the front of the wall However, in the segmental grid retaining wall method, the relative movement between the individual headers and stretchers was generally recognized, and stress redistribution in the gravel filling was also observed when subjected to the external loading and self-weight of filling Therefore, it has been thought that the distribution of the earth pressure in the segmental grid retaining wall system differ from that of the concrete retaining wall In this study, the surcharge tests using the scaled model segmental grid retaining wall was carried out to observe the distribution of the earth pressure in the segmental grid retaining wall The earth pressure was measured in the six specified height of wall, and the distribution of the pressure was analyzed. Furthermore, the earth pressure by computation or by the test using the concrete retaining wall was also considered to make comparison

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.172-175
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• 2001

The high temperature deformation behavior of two-phase gamma TiAl alloy has been investigated with the variation of temperature and ${\gamma}/{\alpha}_2$ volume fraction. For this purpose, a series of load relaxation tests and tensile tests have been conducted at temperature ranging from 800 to $1050^{\circ}C$. In the early stage of the deformation as in the load relaxation test experimental flow curves of the fine-grained TiAl alloy are well fitted with the combined curves of two processes (grain matrix deformation and dislocation climb) in the inelastic deformation theory. The evidence of grain boundary sliding has not been observed at this stage. However, when the amount of deformation is large (${\epsilon}{\approx}$ 0.8), flow curves significantly changes its shape indicating that grain boundary sliding also operates at this stage, which has been attributed to the occurrence of dynamic recrystallization during the deformation. With the increase in the volume fraction of ${\alpha}_2$-phase, the flow stress for grain matrix deformation increases since ${\alpha}_2$-Phase is considered as hard phase acting as barrier for dislocation movement. It is considered that cavity initiation is more probable to occur at ${\alpha}_2/{\gamma}$ interface rather than at ${\gamma}/{\gamma}$ interface.

• Clinical and Experimental Pediatrics
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• v.50 no.8
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• pp.711-717
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• 2007

Sleep is a vital, highly organized process regulated by complex systems of neuronal networks and neurotransmitters. Normal sleep comprises non-rapid eye movement (NREM) and REM periods that alternate through the night. Sleep usually begins in NREM and progresses through deeper NREM stages (2, 3, and 4 stages), but newborns enter REM sleep (active sleep) first before NREM (quiet sleep). A period of NREM and REM sleep cycle is approximately 90 minutes, but newborn have a shorter sleep cycle (50 minutes). As children mature, sleep changes as an adult pattern: shorter sleep duration, longer sleep cycles and less daytime sleep. REM sleep is approximately 50% of total sleep in newborn and dramatically decreases over the first 2 years into adulthood (20% to 25%). An initial predominant of slow wave sleep (stage 3 and 4) that peaks in early childhood, drops off abruptly after adolescence by 40% from preteen years, and then declines over the life span. The hypothalamus is recognized as a key area of brain involved in regulation of sleep and wakefulness. The basic function of sleep largely remains elusive, but it is clear that sleep plays an important role in the regulation of CNS and body physiologic processes. Understanding of the architecture of sleep and basic mechanisms that regulate sleep and wake cycle are essential to evaluate normal or abnormal development of sleep pattern changes with age. Reduction or disruption of sleep can have a significant impact on daytime functioning and development, including learning, growth, behavior, and emotional regulation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.11
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• pp.963-971
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• 2000

In order to investigate the effects of an electric field on EHD(Electro-hydrodynamic) nucleate boiling hat transfer characteristics in a nonuniform electric field under saturated pool boiling, the basic study has been performed experimentally. In the present study, the working fluid is R-113 and the plate-wire electrode system is used to generate a steep electric field gradient. Boiling parameters are investigated by using a high speed camera. The electric field distribution around a wire is obtained to understand the effect of an electric field on bubble departure/movement. The experimental results show EHD effects are much more considerable when the applied voltage increases. Bubbles depart away from the heated wire in radial direction. It is confirmed that the mechanisms of EHD nucleate boiling are closely connected with the dynamic behavior of bubbles. The boiling parameters are significantly changed by the electric field strength. With increasing applied voltages, the bubble size decreases and the nucleation site density, bubble velocity and bubble frequency increase.

• Journal of Korea Game Society
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• v.14 no.5
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• pp.87-96
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• 2014

In developing games, realism is considered as an important factor to increase immersion. To do this, the paper developed 'Jungle Master' game applying the conventional energy model to movement of monsters in RPG. The main scenario of the game is that animals attack each other in order to survive the competition in jungle. While chasing monster : fleeing monster is 1:1 in the conventional energy model, it is extended as n:1 in order to increase fun. As the results, this paper showed that the energy model can be effectively applied to the real game and monsters can be implemented so that they can move in natural.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.659-664
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• 2002

New design method about the spread footing was developed using only soil and geosynthetics. This footing will be able to replace the concrete footing at constructing the foundation of small structures. As shown in Fig-3(b), after excavating the ground in semicircular shape, geosynthetics is layed on the semicircular shape of ground and let the soil filled. Geosynthetics of upper side are fixed tightly each other It can be thought to be a kind of great bag with semicircular shape. We performed two kinds of experiments to investigate the deformation and the failure shape of spread footing reinforced by geosynthetics. First, after making model ground with aluminium rods, the lattice point of 1cm ${\times}$ 1cm size of the side of aluminium rods have been painted with various kinds of colors. We have observed the movement of painted rods during loading. Second, we have taken pictures about failure process using B-shutter method. Analysing the behavior of model ground reinforced in a semicircular shape, we could know the reinforced one has much greater and wider plastic area than unreinforced one at failure. Based on the experimental results, new design method was proposed, which has a possibility to apply at the field works.

• Korean Institute of Interior Design Journal
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• v.17 no.2
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• pp.102-110
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• 2008

Construction space of Japan suggests the factor of speculation to human and reveals tradition. The speculation can be embodied in the aspect of space and human's mental aspect is expressed as a main factor of tradition space of Japan. The purpose of this study is to research expression characteristic of speculation space, shown in the architecture of modem architect, Tadao Ando, who succeeds the concept. His works surveyed through research contain the emotion of nature and human, which are traditional factors of Japan. Moreover, it is reinterpreted by modem space, delivers its function of space and physical factor to user and grants value to activity and behavior of user residing in the space. Users recognize movement, create new meaning of space and accept physical barrier in the space. In conclusion, it can be said that the space of speculation is not a simple visual thing but a frame of visual structure, which is invented for embodiment. The factors show the Japanese architecture, real and contemplating one, which is positive in real life and allows experience. Through the conditions above, the researcher can find the meaning from the aspect that modem architecture of Japan is planned on the basis of concept of speculation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.6
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• pp.907-917
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• 1997

The purpose of this study is to design an anti-sway motion for industrial overhead cranes which transport objects on a horizontal plane by adjusting movements of a trolley motor and a girder motor. The movement of a hoist motor has not been considered at this time since its role was assumed to move objects only vertically, therefore, not to affect the swing motion of objects. The dynamic behavior of the swing motion shows nonlinear characteristics, which makes the design of anti-sway motion controller difficult. First of all, the nonlinear state equation for the motion of industrial overhead cranes has been derived. Then they have been linearized about normal operating states determined by the dynamic characteristics of motor motion-acceleration, constant speed, and deceleration, and deceleration, during transportation. The partial state feedback control algorithm based on this linearized state equation has been developed on order to suppress the swing motion. The simulation results have demonstrated satisfactory performance of the proposed controller.

• Journal of Aerospace System Engineering
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• v.9 no.4
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• pp.23-30
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• 2015

The focal plane image stabilization for a camera is one of the most effective method that can increases the digital camera's image quality by compensating the vibration disturbance. The optical image stabilization can be implemented by making the focal plane to trace the path of incident light. To control the position of focal plane motion compensating stage precisely, a nonlinear control algorithm has been applied by considering coulomb friction which is nonlinear behavior of the compensator system. In our study, we have analyzed the hand shaking vibration using the gyro sensor, and made a mathematical model of compensating stage containing optical sensor and piezo-actuator. Then the nonlinear control algorithm has been designed and its performance has been verified by experiment. In this study, a friction driven peizo-electric actuator with $1{\mu}m$ resolution and 10mm/s speed has been used for stage movement.

• YAKHAK HOEJI
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• v.40 no.5
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• pp.545-549
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• 1996

Male Sprague-Dawley rats were exposed to the toluene at 3,000${\pm}$200ppm via inhalation for two hours in the single inhalation group and three weeks by two hours per day, six da ys per week in the repeated inhalation group. The blood toluene concentration in the repeated inhalation group was significantly lower than that in the single inhalation group after 210 and 240 minutes of exposure. The peak concentration of blood toluene was 58.13${\pm}$4.63${\mu}$g/ml in the single inhalation group and 54.24${\pm}$6.87mcg/ml in the repeated at the end of 120 minutes of the exposure. The behavioral change of rats for the initial 30 minutes of the toluene inhalation showed mildly increased movement and excitement but remained calm and inhibitory behaviors after that period; more inhibitory behaviors in the single inhalation group compared with the repeated inhalation group. In open-field test, after the termination of the toluene inhalation, no difference had been statistically observed between the toluene inhalation group and the control group in ambulation, rearing, preening and grooming.