• The Korean Journal of Physiology and Pharmacology
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• 제17권6호
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• pp.511-516
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• 2013

Bladder cancer is the seventh most common cancer in men that smoke, and the incidence of disease increases with age. The mechanism of occurrence has not yet been established. Potassium channels have been linked with cell proliferation. Some two-pore domain $K^+$ channels (K2P), such as TASK3 and TREK1, have recently been shown to be overexpressed in cancer cells. Here we focused on the relationship between cell growth and the mechanosensitive K2P channel, TREK2, in the human bladder cancer cell line, 253J. We confirmed that TREK2 was expressed in bladder cancer cell lines by Western blot and quantitative real-time PCR. Using the patch-clamp technique, the mechanosensitive TREK2 channel was recorded in the presence of symmetrical 150 mM KCl solutions. In 253J cells, the TREK2 channel was activated by polyunsaturated fatty acids, intracellular acidosis at -60 mV and mechanical stretch at -40 mV or 40 mV. Furthermore, small interfering RNA (siRNA)-mediated TREK2 knockdown resulted in a slight depolarization from $-19.9mV{\pm}0.8$ (n=116) to $-8.5mV{\pm}1.4$ (n=74) and decreased proliferation of 253J cells, compared to negative control siRNA. 253J cells treated with TREK2 siRNA showed a significant increase in the expression of cell cycle boundary proteins p21 and p53 and also a remarkable decrease in protein expression of cyclins D1 and D3. Taken together, the TREK2 channel is present in bladder cancer cell lines and may, at least in part, contribute to cell cycle-dependent growth.

• 대한기계학회논문집B
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• 제27권8호
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• pp.1023-1032
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• 2003

The effect of local forcing on the separated flow over a backward-facing step is investigated through hot-wire measurements and flow visualization with multi-smoke wires. The boundary layer upstream of the separation point is laminar and the Reynolds number based on the free stream velocity and the step height is 13800. The local forcing is given from a slit located at the step edge and the forcing signal is always defined when the wind tunnel is in operation. In case of single frequency forcing, the streamwise velocity and the reattachment length are measured under forcing with various forcing frequencies. For the range of 0.010〈S $t_{\theta}$〈0.013, the forcing frequency component of the streamwise velocity fluctuation grows exponentially and is saturated at x/h = 0.75 , while its subharmonic component grows following the fundamental and is saturated at x/h = 2.0. However, the saturated value of the subharmonic is much lower than that of the fundamental. It is observed that the vortex formation is inhibited by the forcing at S $t_{\theta}$ = 0.019 . For double frequency forcing, natural instability frequency is adopted as a fundamental frequency and its subharmonic is superposed on it. The fundamental frequency component of the streamwise velocity grows exponentially and is saturated at 0.5 < x/ｈ < 0.75, while its subharmonic component grows following the fundamental and is saturated at x/ｈ= 1.5 . Furthermore, the saturated value of the subharmonic component is much higher than that for the single frequency forcing and is nearly the same or higher than that of the fundamental. It is observed that the subharmonic component does not grow for the narrow range of the initial phase difference. This means that there is a range of the initial phase difference where the vortex parring cannot be enhanced or amplified by double frequency forcing. In addition, this effect of the initial phase difference on the development of the shear layer and the distribution of the reattachment length shows a similar trend. From these observations, it can be inferred that the development of the shear layer and the reattachment length are closely related to the vortex paring.

• 한국통신학회논문지
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• 제36권6C호
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• pp.349-354
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• 2011

수동형(passive) 밀리미터파(millimeter wave) 영상은 의복 등에 은닉된 물체의 탐지가 가능하며 악천후의 상황에서도 감쇄도(attenuation)가 낮아 식별이 가능한 영상을 획득할 수 있다. 그러나 영상 시스템의 공간 해상도(spatial resolution)가 낮고 수신신호가 미약하여 잡음의 영향이 크고 시스템의 온도 분해능(temperature resolution)에 따라 영상의 질이 달라진다. 본 논문에서는 수동형 밀리미터파 영상과 일반 카메라부터 획득되는 영상의 정합(registration)과 은닉된 물체의 시각화를 위한 영상 융합(fusion)을 연구한다. 영상의 정합은 추출된 몸체 경계 간의 상호상관도를 최대로 하는 어파인 변환(affine transform)으로 수행되며 융합은 영상 분해를 위한 이산 웨이블릿 변환(discrete wavelet transform), 융합 법칙(fusion rule), 영상을 복원하기 위한 역 이산 웨이블릿 변환의 3단계로 구성된다. 실험에서는 수동형 밀리미터파 영상 시스템에 의해 칼, 도끼, 화장품, 그리고 휴대폰과 같은 또는 비금속의 다양한 물체가 탐지됨을 보인다. 또한 정합과 융합된 영상의 결과로부터 가시 영상으로부터 얻은 얼굴과 의복 등의 대상자의 신원정보와 밀리미터파 영상으로부터 획득한 은닉된 물체의 정보를 동시에 시각화할 수 있음을 보인다.

• 한국가스학회지
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• 제2권1호
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• pp.28-39
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• 1998

본 연구에서는 $20\%$ 천장개구부가 있는 정사각형 밀폐공간내의 순수자연대류와 자연대류 -복사가 고려된 복합열전달을 순차해석과 실험을 통하여 비교 분석하였다. 수치해석은 순수자연대류에 대하여 SIMPLE 알고리즘을 사용하였고, 복사열전달에 대해서는 S-N 구분 종좌표법을 이용하였으며 난류유동의 경계조건은 벽함수를 적용하였다. 실험은 수치해석의 결과와 비교하기 위하여 동일한 조건에 대하여 수행되었다. 그 결과 순수자연대류와 복합열전달의 유동장, 온도장의 형상은 유사한 유선함수를 보이고 있으며, 유동가시화를 통한 실험결과와 잘 일치하고 있음을 보여준다. 수치해석과 실험의 온도분포를 비교한 결과 평균 $8.5\%$의 오차를 보였다.