• 한국항공우주학회지
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• 제30권8호
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• pp.21-29
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• 2002

본 연구는 다공벽과 공동을 사용한 피동제어법을 천음속 습공기 유동에서 발생하는 충격파와 경계층 간섭에 적응하였다. 지배방정식은 액적성장 방정식과 완전히 결합된 2차원, 비정상, 압축성 Navier-Stokes 방정식이며, 3차 오더 MUSCL 타입의 TVD 기법을 사용하였다. 또 난류모델로는 Baldwin-Lomax 모델을 적용하였다. 본 연구에서 적용한 제어법의 유용성을 조사하기 위해 유동의 전압손실과 충격파 변위의 시간의존성 거동을 해석하였다. 수치계산 결과로부터 본 연구의 피동제어기법을 통해 천음속 습공기 유동에서 발생하는 충격파/경계층 간섭으로 인한 전압손실이 상당히 감소하였고, 익에서 충격파 운동을 억제하는 것으로 나타났다. 또 다공영역의 위치가 본 연구의 제어법의 효과에 상당한 영향을 준다는 것이 발견하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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• pp.306-309
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• 2006

슬롯을 이용한 충격파와 난류 경계층의 간섭유동의 피동제어에 관한 연구가 이루어졌다. 슬롯의 다양한 형상 변화가 간섭유동에 미치는 영향이 관찰되었으며, 이를 위하여 간섭유동 후방에서 피토/벽압력 분포 및 쉴리렌, 오일막 간섭 줄무늬 형상과 같은 유동가시화 정보 등이 얻어졌다. 특정한 슬롯적용의 경우, 충격파를 통한 전압손실의 감소가 관찰되었으나 경계층의 두께는 두꺼워지는 것으로 나타났다.

• 한국멀티미디어학회논문지
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• 제23권2호
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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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• 제34권6호
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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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• 제14권2호
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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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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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.

• 한국해양공학회지
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• 제23권5호
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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.

• 대한토목학회논문집
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• 제7권3호
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• pp.155-164
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• 1987

구조물(構造物)의 안정성(安定性)과 파랑제어기능(波浪制御機能)을 고려(考慮)한 새로운 사석구조물(捨石構造物) 설계법(設計法)을 제안(提案)하였다. 이 설계법(設計法)은 임의의 파랑조건하(波浪條件下)에서 파랑(波浪)의 반사(反射) 및 run-up을 저감(低減)시키고, 안정성(安定性)을 증대(增大)시키는 설계개념(設計槪念)을 가졌다. 설계식(設計式)은 허용파괴율(許容破壞率)과 안정성(安定性)에 대한 파군특성(波群特性)의 영향(影響) 도입(導入)하여 유도하였으며, 이에는 해안파(海岸波)의 평균(平均) run-sum이라는 새로운 외력개념(外力槪念)이 사용(使用)되었다. 마지막으로 이 새로운 설계법(設計法)에 의한 일양단면(一樣斷面)과 복합단면(複合斷面) 사석구조물(捨石構造物) 설계예(設計例)로부터 이 설계법(設計法)의 유용성(有用性)과 이점(利點)을 검증(檢證)하였다.

• The Journal of Korean Physical Therapy
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• 제20권1호
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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.

• 동아시아경상학회지
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• 제6권4호
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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.