• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.887-893
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• 2005

The aggregability of red blood cells (RBCs) was determined by laser backscattering light analysis in a microfluidic channel. Available techniques for RBC aggregation often adopt a rotational Couette-flow using a bob-and-cup system for disaggregating RBCs, which causes the system to be complex and expensive. A disposable microfluidic channel and vibration generating mechanism were used in the proposed new detection system for RBC aggregation. Prior to measurement, RBC aggregates in a blood sample were completely disaggregated by the application of vibration-induced shear. With the present apparatus, the aggregation indexes of RBCs can be measured easily with small quantities of a blood sample. The measurements with the present aggregometer were compared with those of LORCA and the results showed a strong correlation between them. The aggregability of the defibrinogenated blood RBCs is markedly lower than that of the normal RBCs. The noble feature of this design is the vibration-induced disaggregation mechanism, which can incorporate the disposable element that holds the blood sample.

• 한국정밀공학회지
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• 제16권6호
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• pp.141-147
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• 1999

Optical disk technology with a laser beam for data recording and retrieval is one of the most promising route for high density information storage in multimedia era. As the storage density and data transfer rates are increased, mechanical issues, mainly noise and vibration, become critical. Rubber materials are extensively used in various machine design application, mainly for vibration/shock/noise control devices. Over the years an enormous effort has been put into developing procedures to provide properties of rubber components with complex shape and under pre-deformed state. In this paper, non-linear large deformations of a rubber mount for optical disk drive were investigated using the finite element method. A tension test of rubber material was performed, to calculate a strain energy function. According to the pre-deformed state, the variation of rubber mount stiffness were calculated and the reliability of numerical results were checked by compared with the measuring the deflection values. Also, the effects of the pre-deformed rubber mount on the system dynamic characteristics were investigated and the relation between the static stiffness variation of rubber mount and the natural frequence variation of system was discussed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.198-203
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• 2002

A fuzzy logic controller design technique is proposed to apply for the control of flexible system under irregular disturbance. The fuzzy rules of $\ulcorner$Mode Selecting Fuzzy Controller$\lrcorner$ are constructed using displacement, velocity information and modal characteristics of the system. The frequency information of flexible system is picked up from $\ulcorner$Mode Selecting Unit$\lrcorner$ based on Fast-Fourier transform algorithm. Experiment is conducted to verify the proposed theoretical approach, Piezo ceramic and laser accelerometer are used as actuator and sensor in the experiments respectively

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.226-233
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• 2003

There are many researches going on to develop the information storage devices using Blue-ray disc and DVD as a demand for high-density information storage devices is highly increasing. This high-density information storage device requires a short-wave laser and objective lens of high numerical aperture set in fer its operation. And, that brings out rapid decrease of tilt tolerance. Therefore, it is necessary that an actuator should control tilt motions to get a stable signal. In this paper, a new mathematical form of 3-D.O.F coupled model is formulated and magnetic circuit in constraints is most effectively designed with the use of the moving coil type actuator in higher sensitivity. Further, this paper presents a tilt coil whose rotational center point is put on that of the lens through the variation of tilt coil and proposes a 3-axis actuator with high sensitivity improved in its dynamic property through its structure analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2225-2227
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• 2002

This paper presents the control and the performances of a $H_2$ controller for active vibration control of a cantilever beam. Electromagnets are used as actuators and a laser sensor is used to measure the position of the bending beam. The transfer function of the beam is obtained via the modal analysis of the free vitiation equation. The performance of the controller are verified by experimental results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.168-171
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• 2005

The present study describes the prediction of the flow induced noise level of a high-speed rotating hexagonal disk and proposes the way how to reduce it. Since a hexagonal disk, which is used in the laser printer and named a polygon mirror, has six sharp comers, there are low and high pressure regions on each of six edges when it rotates. Therefore, the Pressure difference generates three dimension flow field and causes aerodynamic noise. The Ffowcs-Williams and Hawkings(FWH) method is employed for the analysis. We have measured the sound pressure levels and compared them with the computational results. The calculated sound pressure levels agree well with the experimental results. We modified the shape of the edges of a hexagonal disk to reduce the noise level and confirm their effects through numerical computation.

• 전자공학회논문지
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• 제53권10호
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• pp.109-115
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• 2016

이 논문에서는 레이저를 통한 진동판 스캔과 열화상 카메라를 사용한 진동판 촬영, 두 가지 방법을 비교하며 슬림 스피커의 분할 진동을 검출하는 방법에 대해 살펴본다. 슬림 스피커는 평판형의 구조적인 특성상 분할진동이 두드러지게 나타나고, 설치되는 공간이 좁아 무빙 코일에서 발생하는 열의 냉각이 제한적이다. 이런 특성으로 인해 슬림 스피커에서 분할진동이 제품의 품질에 큰 영향을 미친다. 본 연구에서는 진동판에서 일어나는 분할진동의 영향과 무빙 코일에 의한 진동판의 열전달 관계를 비교 탐색한다. 비교를 위한 실험은 분할진동 모드의 측정과 진동판의 열 변화 측정을 진동판 스캔과 열화상 카메라 촬영의 2단계의 실험으로 진행한다. 동일 주파수에서 발생하는 분할진동 모드와 열전달 형태를 비교하여 서로 간에 어떤 영향을 미치고 있는 지 파악할 수 있다. 그리고 이를 통해 발견한 연관성을 통해 쉽게 촬영할 수 있는 열화상만으로도 슬림 스피커가 가지는 분할진동의 형태와 경향성을 빠르게 파악하여 최적 설계에 도움이 되는 자료로 사용할 수 있을 것이다.

• 한국소음진동공학회논문집
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• 제16권1호
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• pp.40-49
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• 2006

A novel disturbance measurement method, model based disturbance observer (MBDO) for optical disk drives (ODDs), is proposed and the disturbance analysis using the proposed method is performed under various conditions. In ODDs, the quantitative and qualitative analysis for the generated disturbance during normal operation is very important to successful servo loop design. However, the disturbance measurement is difficult, and high precision measurement is necessary. Furthermore, the conventional disturbance measurement method using a LDV (laser Doppler vibrometer) has many difficulties in eccentricity direction due to the vertical movement of an optical disk. To solve this problem, the MBDO is proposed. First, the relationship between the servo loop for ODDs and the generated disturbance are briefly reviewed. Second, the principle of the MBDO is introduced, and the disturbance measurement results, which are measured by the MBDO and a LDV, are compared. In these experiments, test DVD-ROM disks are used to generate quantitative/qualitative disturbance. Then, the disturbance analysis under various conditions is performed using waterfall technique. This technique clearly shows the disturbance trend from the inner part of an optical disk to the outer part of it. Finally, the various disturbances measurement results are summarized and some remarks for it are commented.

• Korea-Australia Rheology Journal
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• 제17권1호
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• pp.9-13
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• 2005

The aggregation of red blood cells (RBCs) is a major determinant of blood flow resistance passing through various veins. Available techniques for measuring RBC aggregation often require pretreating and washing after each measurement, which is not optimal for day-to-day clinical use. A laser reflection technique has been combined with a vibration-aided disaggregation mechanism, which shows significant advances in aggregometer design, operation and data analysis. The essential features of this design are in its simplicity and a disposable element that is in contact with the blood sample. Using extremely small quantities of blood, the RBCs subjected to vibrations can be quickly and completely disaggregated. This is followed by measuring the backscattered light intensity. The measurements with the present sensor were compared with those of a commercial aggregometer and a strong correlation was found between them. The newly-developed optical aggregometer can measure the RBC aggregability difference between young and old cell suspension with ease and accuracy.

• Nuclear Engineering and Technology
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• 제42권6호
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• pp.704-711
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• 2010

Modal testing requires measuring the vibration of many points, for which an accelerometer, a gab sensor and laser vibrometer are generally used. Conventional modal testing requires mounting of these sensors to all measurement points in order to acquire the signals. However, this can be disadvantageous because it requires considerable measurement time and effort when there are many measurement points. In this paper, we propose a method for modal testing using a camera image. A camera can measure the vibration of many points at the same time. However, this task requires that the measurement points be classified frame by frame. While it is possible to classify the measurement points one by one, this also requires much time. Therefore, we try to classify multiple points using pattern recognition. The feasibility of the proposed method is verified by a beam experiment. The experimental results demonstrate that we can obtain good results.