• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.8
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• pp.21-29
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• 2002

In the present study, a passive control method, using a porous wall and cavity system, is applied to the shock wave/boundary layer interactions in transonic moist air flow. The two-dimensional, unsteady, compressible, Navier-Stokes equations, which are fully coupled with a droplet growth equation, are solved by the third-order MUSCL type TVD finite difference scheme. Baldwin-Lomax model is employed to close the governing equations. In order to investigate the effectiveness of the present control method, the total pressure loss of the flow and the time-dependent behaviour of shock motions are analyzed in detail. The computed results show that the present passive control method considerably reduces the total pressure losses due to the shock wave/boundary layer interaction in transonic moist air flow and suppresses the unsteady shock wave motions over the airfoil as well. It is also found that the location of the porous ventilation significantly affects the control effectiveness.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.306-309
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• 2006

Passive control of the shock wave/turbulent boundary-layer interaction control utilizing slotted plates over a cavity has been carried out. Effect of various slot configurations on the characteristics of the interactions are tested. Pitot/wall surface pressure distributions and flow visualizations including Schlierens and interference fringe patterns over a thin oil-film have been obtained at the downstream of the shock interactions. It was found that the interaction control by a certain slot-configuration could lead a reduction of the total pressure loss through the shock wave, however, the boundary layer thickness became thicker as compared with the case of no control.

• Journal of Korea Multimedia Society
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• v.23 no.2
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• pp.204-215
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• 2020

People who have sleep disorders such as insomnia take a long time to get to sleep, namely sleep latency. In order to reduce it, effective stimulations and environments to induce sleep such as ASMR or pink noise are necessary. However these have different effects and preferences for each individual. Therefore customized service and control for the sleep induction will be provide to him/her. In this paper, we proposed SIS control system which provides selectively sound control among various kinds of ASMR and pink noise according to sleep state measured from brain wave data for an individual. In order to verify the effectiveness of the system, we had conducted totally 30 experiments for 5 people, and all EEG data measured from all the people during sleep. An average of 3.7 hours was spent per experiment. In comparison experiments with and without sound control for sleep induction, the latency time was reduced by an average of 8 minutes as well as delta waves and theta waves, which appear only in deep sleep, are increased by 21%.

• Journal of Welding and Joining
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• v.34 no.6
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• pp.69-74
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• 2016

Because the pure titanium has superior corrosion resistance and formability compared with different material, it is widely used as material of welded heat exchanger. When the welding of heat exchanger is carried out, certain area in which welding start and end are overlapped occurs. The humping of back bead is formed in the overlap area due to partial penetration. Thus in this study, the experiments were carried out by changing the length and wave shape of overlap area, and then the weldabiliay was evaluated through the observation of microstructure, the measurement of hardness and tensile-shear strength test in the overlap area. When overlap length was 9.8mm, humping bead was suppressed. The microstructure of overlap area coarsened and its hardness increased due to remelting. As a result of tensile-shear strength test in the overlap area according to applying the wave shape control, it was confirmed that the overlap area applied wave shape control had more excellent yield strength and ductility.

• The Korean Journal of Physiology
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• v.14 no.2
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• pp.21-28
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• 1980

In order to investigate the effect of cholinergic substance on the electrical and the mechanical activities of the stomach muscle, 10 isolated cat stomachs were studied. At various sites of a stomach muscle preparation, the electrical activity was monopolarly recorded by using capillary electrodes containing chlorided silver wires, and the isometric contractile activity was recorded simultaneously at the terminal portion of the antrum in Krebs solution$(36^{\circ}C)$ which was aerated with a gas mixture consisting of 95% $O_2$ and 5% $CO_2$. The recording of these activities were performed before (control period) and after acetylcholine$(10^{-5}M)$ and atropine $(10^{-6}M)$ administrations serially. Following results were obtained: 1) The mean frequency of the slow wave was $4.36{\pm}0.22\;cycles/min$ at all the various sites of the cat stomach. The slow wave was propagated caudad in sequence and its velosity of propagation increased as the slow wave approached the pylorus in normal Krebs solution. 2) After acetylcholine administration, the frequency of the slow wave increased transiently and the increase of slow wave frequency was followed by the isometric contraction of antral muscle in association with the second potential which succeeded the slow wave. 3) By atropine administration, the stimulatory effect of acetylcholine on the antral muscle contraction was abolished completely, and the frequency of the slow wave decreased significantly compared with that of the control period, which tendency was more prominent in the antrum. The above results suggest that the transient increase in the frequency of gastric slow wave by acetylcholine may have some influence upon the contraction mechanism of the cat antral muscle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.962-965
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• 2005

A high intensity progressive wave tube is installed at Korea Aerospace Research Institute (KARI) for acoustic environmental tests. The test facility has 700 mm x 800 mm cross-sectional area, and provides acoustic environment of 165 dB over the frequency range of $25Hz{\sim}10,000Hz$. The facility consists of a 6 m long acoustic wave tube, acoustic power generation systems, gases nitrogen supply systems, and acoustic control systems. This paper describes how the basic parameters of the facility and power generation systems are controlled to meet the requirement of the test. The shape and length of the tube has been designed by using the size of test objects and the wave propagation characteristics of the tube. The capacity of acoustic power generation systems is determined by the energy conversion of acoustic wave and the efficiency of acoustic modulators. Moreover, the paper introduces test run results of the tube. Overall of 163dB has been generated by using the test facility.

• Journal of Ocean Engineering and Technology
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• v.23 no.5
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• pp.15-24
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• 2009

The results of a simulation study of variable liquid column oscillations in U-tanks with a novel control scheme are presented. The configuration under investigation is analogous to that of the tuned liquid-column damper used to suppress oscillatory motion in large structures like tall buildings and cargo ships. However, by virtue of an adequate controller, the response of amplitude of the U-tanks becomes larger in a desired frequency range. The motion of wave energy conversion system equipped with a variable liquid column oscillator is described by a series of nonlinear differential equations. The equations describe the motion of body under ocean wave excitation, and the motion of liquid with an air-spring effect caused by the compression and expansion of air in vertical liquid columns and air chambers. It is shown that the effect of the air-spring has a vital role to maintain the natural frequency of oscillation in the system to synchronize with the frequency of the ocean wave, thus the system provides the most effective mode for energy extraction from the ocean.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.3
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• pp.155-164
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• 1987

A new design method of rubble mound structures that includes the considerations of stability and wave control is proposed. Using the method, design of structures that reduce the wave reflection and run-up and increase the rubble stability is assured under the given wave conditions. The new design formula is developed so that the allowable prcentage of damage and the wave grouping effects on rubble stability are also considered in design. For this a new definition of the mean run-sum is made. Finally, the new method is applied for the design of uniform and composite slope rubble mound structures and the significant advantages are found.

• The Journal of Korean Physical Therapy
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• v.20 no.1
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• pp.75-79
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• 2008

Purpose: The purpose of this study was to investigate the effect of $\alpha$-wave music and art appreciation on hand function. Methods: A total of 22 university students participated in this study (10 males and 12 females). Twelve subjects received $\alpha$-wave music and art appreciation. The other subjects received neither. All subjects were assessed for hand function (manual dexterity, power grip, pinch, lateral pinch, tactile sense) using a Purdue pegboard, dynamometer, pinch gauge, and Semmes-Weinstein monofilament wire. The data were analyzed using paired and independent t-tests. Results: The results were as follows: 1. In the experimental group, manual dexterity and tactile sense were significantly increased between pre- and post-intervention (p<0.05). Within the control group, manual dexterity and power grip were significantly increased between pre- and post-test (p<0.05). 2. With regard to dexterity and tactile sense, the experimental group experienced a significant post-intervention increase compared to the control group (p<0.05). There was no significant difference in power grip, pinch, or lateral pinch changes between the two groups (p>0.05). Conclusion: The results of this study show that $\alpha$-wave music and art appreciation affect hand function with regard to manual dexterity and tactile sense.

• East Asian Journal of Business Economics (EAJBE)
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• v.6 no.4
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• pp.25-34
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• 2018

Purpose - The purpose of this study is to investigate the effect of Korean Wave on consumer intentions by adjusting the Korean image and image of Korean company to counterbalance the hostility through the control effect of Korean Wave. Research design and methodology - This paper measure individual and national hostility and suggest that the effect of the adjustment of Korean culture satisfaction on corporate image, product image and consumer's purchase intention. Results - This study suggests the subjects to be studied empirically by presenting research themes and models, but it is necessary to verify the model through statistical verification since it is not verified empirically. In addition, it is necessary to further control factors and identification of anti-marginal or anti-marginal products. Conclusions - This study suggests research topics that investigate how hostility affects Korean Wave in consideration of the current special situation, while conventional researches mainly focus on ethnocentrism and patriotism. In this way, this study suggests research direction that helps to enhance corporate image and product image by eliminating hostility and actively utilizing Korean Wave. The Proposal will be helpful to provide a frame for empirical analysis in future and to develop strategic means to further utilize it in international marketing.