• 대한약침학회지
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• 제16권4호
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• pp.30-35
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• 2013

Objectives: This study was designed to investigate the effects of Calculus Bovis-Fel Uris-Moschus pharmacopuncture (BUM) on the regional cerebral blood flow (rCBF) and the mean arterial blood pressure (MABP) in normal and cerebral ischemic rats and to investigate a possible pathway involved in the effects of BUM. Methods: The changes in the rCBF and the MABP following BUM into Fengfu (GV16) were determined by using a laser-Doppler flow meter and a pressure transducer, respectively. Results: BUM significantly increased the rCBF and decreased the MABP in normal rats in a dose-dependent manner. The effect on the rCBF was significantly inhibited by pretreatment with methylene blue (0.01 mg/kg, intraperitoneal), an inhibitor of guanylate cyclase, but was not affected by pretreatment with indomethacin (1 mg/kg, intraperitoneal), an inhibitor of cyclooxygenase. The BUM-induced decrease of the MABP was changed neither by methylene blue nor by indomethacin pretreatment. In the cerebral ischemic rats, the rCBF was stably increased upon cerebral reperfusion in the BUM group in contrast to the rapid and marked increase in the control group. Conclusion: This study demonstrated that BUM into Fengbu (GV16) increased the rCBF in a dose-dependent manner in the normal state; furthermore, it improved the stability of the rCBF in the ischemic state upon reperfusion. Also, the effects of BUM on the rCBF were attenuated by inhibition of guanylate cyclase, suggesting that the effects involved the guanylate cyclase pathway.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.751-758
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• 2002

Boreholes that are drilled in soft or unconsolidated materials such as gravels and coals are prone to collapse. To maintain the hole, some kinds of casing pipes are needed. If thereby a plastic pipe e.g. PVC is used for the casing, Televiewer tool is still capable of detecting structural features such as fractures in the borehole wall behind the pipe, whereas other borehole-imaging logging devices such as BIPS (Borehole Image Processing System) and FMS(Formation Micro Scanner) won't provide any information about that. Televiewer's primary component is a piezoelectric transducer centered in the hole. It acts as both a transmitter and receiver, and sends an ultrasonic beam. That is reflected, in the same manner as the seismic wave propagation, from the both sides(inner and outer surfaces) of the casing pipe, transmits through the pipe and then reflected from the borehole wall. With an appropriate choice of time-windowing, it is possible to capture the returning signals from both the borehole wall and the outer side of casing pipe as well. A suite of laboratory tests were performed on various physical models composed of plastic pipes with different diameters. Although the amplitudes of returning signals were reduced to about half the usual value due to the transmission loss, the dynamic range of Televiewer tool was sufficient to observe the structural features behind the casing pipe. Besides, several representative case studies at various research areas in our country are presented. The results demonstrate the usefulness of the transmissivity of Televiewer acoustic km, which will assist in further structural interpretation.

• 한국통신학회논문지
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• 제25권9B호
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• pp.1551-1562
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• 2000

국내에서 개발된 광섬유 격자{FBG)를 사용하여 국내 최초로 3종의 FBG 음향 트랜스듀서를 설계 및 제작하였다. 제작된 FBG 트랜스듀서들에 대하여 수중에서 각각 주파수응답특성 설험을 하고, 그 특성을 분석하였다. 주파수 응답특성실험 결과 C형태는 최대 18 kHz대까지 수중음파 검출이 기능하였다. 또한, 수중에서 넓은 영역에 대한 다중점 신호검출을 구현하기 위하여, 파장분활 방법과 Passive band-pass filter system을 이용하여 어레이 시스템을 구축하고 2개의 B형태 FBG 트랜스듀서에서 주파수 1.3 kHz대까지 다중점 수중 음파 신호검출을 성공하였다. 아울러, 음원의 방향과 각도에 따라 검출 신호의 세기가 변화되므로 음원의 물체에 대한 방향성 검출이 가능함으로서, 향후 FBG 하이드로폰의 실용화 연구에 새로운 기틀을 마련하였다.

• 한국통신학회논문지
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• 제36권4B호
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• pp.405-411
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• 2011

최근 해양 환경 모니터링과 해양 개발에 대한 관심이 증대됨에 따라 수중 무선센서네트워크 구성 및 이를 위한 저전력 수중 통신 모뎀에 대한 연구의 필요성이 제기되고 있다. 이에 본 논문에서는 초소형 무지향성 트랜스 듀서를 탑재한 수중 음향 통신 모뎀을 설계하고 구현한다. 또한, 개발한 모뎀을 사용하여 수조와 실외 환경에서 공급 전압과 통신 거리에 따른 성능 실험을 실시하고 결과를 분석한다. 실외 환경에서의 실험 결과에 의하면, 개발한 모뎀에 12 V를 공급하였을 때 40 m 거리에서 200 bps, $10^{-3}$ 비트오율로 단방향 수중 무선 통신이 가능하였다. 본 논문에서 구현한 모뎀은 초소형, 저전력, 무지향성 특성을 가지므로 수중 무선센서네트워크에 기반한 다양한 응용 시스템에 적용될 수 있을 것으로 기대된다.

• 대한기계학회논문집A
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• 제41권4호
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• pp.333-336
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• 2017

스피커 진동판은 고유 특성에 의해 분할진동을 발생 시킨다. 이 분할진동은 진동판의 형상 변화를 가져올 정도로 뚜렷한 영향을 주는데, 본 논문에서는 IT 분야의 첨병인 스마트 폰을 포함한 초박형 멀티미디어 기기에서 많이 사용되는 마이크로 스피커를 그 대상으로 삼는다. 마이크로 스피커는 일반적인 스피커와 다른 평판형의 구조적인 형태와 공간적인 제약이 존재한다. 특히 구동 공간이 밀폐형으로 설계되어 무빙 코일에서 발생하는 열의 냉각이 열악하고 보조적인 서스펜션 구조를 갖추기 어렵다. 본 연구에서는 진동판의 열전달과 분할진동 모드의 연관성을 연구한다. 이를 위해 진동판의 레이저 스캔을 통한 분할진동 측정과 열화상 카메라 촬영을 통한 열변화 측정의 두 단계로 나누어 실험을 진행한다. 이를 통해 특정 주파수 범위에서 분할진동 모드와 열전달 형태를 비교함으로써, 열화상 카메라를 통한 촬영 결과로 진동판 분할진동 모드의 경향성을 빠르게 예상할 수 있어, 마이크로 스피커의 최적 설계에 도움이 되는 지표를 제공할 수 있을 것으로 기대한다.

• 한국식품과학회지
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• 제46권4호
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• pp.516-521
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• 2014

전립선암은 발병률이 높은 암종 중에 하나이다. 전립선 치료제인 flutamide는 androgen 수용체의 호르몬 치료제로서 내성효과에 대한 기본 메커니즘은 명확하지 않다. 본 연구에서는 flutamide에 의해 유도되는 호르몬 불응성 전립선 암세포 성장에서 포도 성분인 resveratrol의 억제효과를 조사하였다. 본 연구의 결과를 통해 호르몬 비의존적인 신호전달의 전환으로 유발되는 호르몬 불응성 전립선 암에서 resveratrol은 예방 및 항암효과에 기여할 것이라 판단된다.

• Smart Structures and Systems
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• 제12권2호
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• pp.97-119
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• 2013

This paper presents numerical and experimental results on the use of guided waves for structural health monitoring (SHM) of crack growth during a fatigue test in a thick steel plate used for civil engineering application. Numerical simulation, analytical modeling, and experimental tests are used to prove that piezoelectric wafer active sensor (PWAS) can perform active SHM using guided wave pitch-catch method and passive SHM using acoustic emission (AE). AE simulation was performed with the multi-physic FEM (MP-FEM) approach. The MP-FEM approach permits that the output variables to be expressed directly in electric terms while the two-ways electromechanical conversion is done internally in the MP-FEM formulation. The AE event was simulated as a pulse of defined duration and amplitude. The electrical signal measured at a PWAS receiver was simulated. Experimental tests were performed with PWAS transducers acting as passive receivers of AE signals. An AE source was simulated using 0.5-mm pencil lead breaks. The PWAS transducers were able to pick up AE signal with good strength. Subsequently, PWAS transducers and traditional AE transducer were applied to a 12.7-mm CT specimen subjected to accelerated fatigue testing. Active sensing in pitch catch mode on the CT specimen was applied between the PWAS transducers pairs. Damage indexes were calculated and correlated with actual crack growth. The paper finishes with conclusions and suggestions for further work.

• Smart Structures and Systems
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• 제4권6호
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• pp.727-740
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• 2008

A down hole vertical seismic array is a sequence of instruments installed at various depths in the earth to record the ground motion at multiple points during an earthquake. Numerous studies demonstrate the unique utility of vertical seismic arrays for studying in situ site response and soil behavior. Examples are given of analyses made at two sites to show the value of data from vertical seismic arrays. The sites examined are the Lotung, Taiwan SMART1 array and a new site installed at Jingliao, Taiwan. Details of the installation of the Jingliao array are given. ARX models are theoretically the correct process models for vertical wave propagation in the layered earth, and are used to linearly map deeper sensor input signals to shallower sensor output signals. An example of Event 16 at the Lotung array is given. This same data, when examined in detail with a Bayesian inference model, can also be explained by nonlinear filters yielding commonly accepted soil degradation curves. Results from applying an ARMAX model to data from the Jingliao vertical seismic array are presented. Estimates of inter-transducer soil increment resonant frequency, shear modulus, and damping ratio are presented. The shear modulus varied from 50 to 150 MPa, and damping ratio between 8% and 15%. A new hardware monitoring system - TerraScope - is an affordable 4-D down-hole seismic monitoring system based on independent, microprocessor-controlled sensor Pods. The Pods are nominally 50 mm in diameter, and about 120 mm long. An internal 16-bit micro-controller oversees all aspects of instrumentation, eight programmable gain amplifiers, and local signal storage.

• 대한치과보철학회지
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• 제44권1호
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• pp.40-50
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• 2006

Statement of problem: $Periotest^(R)\;and\;Osstell^{TM}$ were known as the most objective and quantitative mobility tests available for evaluating stability of implant in vivo. Although a correlation between PTV widely used and ISQ recently introduced exist, a PTV was corresponded to various ISQ. A correct evaluation of implant stability could be obtained only after one has a thorough understanding of the limitations of devices and factors that affect measurements. Purpose: The purpose of this study was to investigate the causes of variables in the values obtained with these two tests. Material and method: A total of 333 implants 134 $Br{\aa}nemark$, 5 Silhouette and 194 ITI implants were investigated. Result: 1. There was a correlation between PTV and ISQ (Spearman correlation =0.39, p<0.0001) 2. The factors that affected ISQ were diameter of implant future, location of implant and implant system (submerged type vs non-submerged type). 3. The factors that affected W were dimeter of implant future, location of implant, and elapsed time after implant placement. 4. There was no significant difference between different surface treatments of RBM, smooth surface and ti-unite on PTY and ISQ. 5. In radiographic finding, no saucerization or bone resorption has been detected in implants with ISQ values that were above the average level of each PTV. These higher values had higher bone densities around the implant fixture. Saucerization was observed in the most impants with ISQ values that were below the average level of each PTV. Conclusion: There was a correlation between ISQ and PTV. However, each measuring methods had factors influencing the measured values. PTV were less sensitive to marginal bone resorption and influenced with the striking point on an implant to the level of bone. With ISQ, the height of implant from bone level to transducer should be considered.

• 한국가스학회지
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• 제16권3호
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• pp.65-70
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• 2012

폭발챔버에서 water gel barrier의 표면형상의 크기에 따른 폭발거동 특성을 조사하기 위하여 실험적 연구를 수행하였다. 단면적 $100{\times}100\;mm^2$, 길이 1600 mm를 가지는 폭발챔버 그리고 점화원으로부터 각각 300 mm, 700 mm 및 1100 mm 떨어진 챔버 바닥면에 $100{\times}200\;mm^2$의 크기에 서로 다른 크기의 표면형상을 고려한 gel barrier를 설치할 수 있도록 제작하였다. 젤라틴 gel과 물을 혼합하여 4가지 크기의 표면형상을 가지는 water gel barrier를 제조하여 실험변수로 사용하였다. 폭발과정 동안 화염전파 과정을 가시화하기 위해 고속카메라 그리고 폭발압력 변화를 관찰하고자 압력획득시스템을 사용하였다. 실험결과, gel barrier의 표면형상의 크기가 커질수록 화염전파과정 및 최대 폭발압력 도달시간은 빠르게 진행되는 것으로 나타났으며, 화염속도 및 폭발압력 또한 증가하는 경향으로 나타났다.