• 한국소음진동공학회논문집
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• 제18권6호
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• pp.606-611
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• 2008

Consumer's product selection measures are being shifted from the units' operational performance to overall performance. Low noise, low vibration, and low power consumption rate, etc. which used to be additional quality indices, now become vital performance factors. Especially, noise and vibration characteristics are being considered as equivalent to/or even more critical than operational performance in certain products such as office machines and home entertainment systems, which share the same space with human being's daily life. Therefore, noise reduction and sound quality improvement technology becomes an inevitable design issue for those applications. Qualitative noise characteristics of rotating polygonal disk applied to digital printer systems are presented. Overall sound pressure level change and tonal noise variation with respect to the geometrical properties of polygonal disk, operational speed, and others are briefly discussed based on experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1594-1596
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• 1996

The NDT(nondestructive test) using pulse echo method with piezoelectric transducers and the system for NDT including image processing were studoed. The system consisted of pulse generator and receiver, two step motors for X-Y scanner, PC-Scope for data aquisition and PC-Lab for trigger and motor driving. We tested and estimated at one point under the following conditions : 1) just water, 2) Aluminum without any crack and 3) Aluminum with hole. The estimated NDT result of whole area (point : $35{\times}20$) is compared with real samples.

• 산업기술연구
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• 제25권A호
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• pp.87-93
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• 2005

Three-dimensional ultrasonic probes being applied to the medical imaging can be grouped into three depending on the scanning methods, which are a mechanical type system, a free-hand system, and 2D phased arrays system. A mechanical type scanner uses a mechanically driven transducer to acquire series of 2D plane images. By integrating these images, a 3-D medical image can be constructed. A motor driving mechanism is a conventional choice for mechanically driving a transducer assembly which picks the raw ultrasonic images up. In this paper we attempt to design a 3D ultrasonic probe which has a operating mechanism of s tilting 3-D scanning. The motion of a transducer assembly of the ultrasonic probe is analytically modelled. We propose a selection procedure for the diameter of a wire rope driving the transducer assembly and the size of torsional spring which gives an initial tension to wire ropes.

• 한국광학회지
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• 제27권5호
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• pp.165-173
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• 2016

본 연구는 2개의 라인 레이저를 이용하여 3차원 형상을 획득하는 방법에 대해 제안한다. 제안하는 방법은 532 nm와 630 nm 파장의 레이저를 이용하여 2-라인 레이저를 생성하고 이를 대상객체에 조사하여 반사되는 빛을 영상센서로 획득하는 것을 통해 3차원 점 데이터를 연산한다. 이를 위해 레이저와 카메라 간의 위치를 결정하고 각 레이저의 평면 방정식 계수를 추정하며 삼각법을 통해 이미지 공간의 라인을 3차원 공간의 점으로 변환한다. 제안하는 시스템은 2개의 라인 레이저와 데이터 정합을 위한 스태핑 모터 제어부와 영상을 획득하고 레이저의 라인을 추출하는 영상처리부, 그리고 추출된 라인으로부터 3차원 점 데이터를 처리하고 3D 모델을 생성하는 3D 모델링부로 나뉜다. 제안하는 방법은 기존 단일 레이저 스캐닝 방식과 비교하여 가려짐으로 인해 발생하는 데이터 소실문제를 해결할 수 있다.

• Journal of Acupuncture Research
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• 제21권6호
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• pp.177-186
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• 2004

Introduction : Recent studies Suggested that there is a strong correlation between acupuncture stimulation and its related cortical activation. Anther study showed that either positive or negative BOLD effects could be observed depending on anatomical structure in acupuncture stimulation. In ttis study, we investigated a new acupoint $KI_6$ (照海), which was known as motor-related acupoint and obtained an evidence that the stimulation of $KI_6$ resulted in either negative or positive BOLD response to stimulation. Methods & Results : 1. Subjects and paradigms : Two separate stimulation paradigms were performed on five healthy (aged 22-23 yrs) in this study. First, the paradigm of acupuncture stimulation was that the acupuncture needle was inserted in acupoints $KI_6$, which is located in lateral side of the foot and then continuously twisted(補瀉를 除外한 捻轉法) for 70 seconds for 10 cycles of activation. During rest period (70 seconds), the needle was completed removed from acupoint. Total 60 cycles were performed and 10 images were obtained per cycle. Second, nonacupoint was randomly selected and the same paradigm was performed as acupoint stimulation. The stimulation protocol comprised 10 cycles of alternating. activation and rest (10 images per cycle). Total 60 cycles were performed and each cycle take about 1.5 sec for motor task. Subjects take an at least 15 minutes break before starting anther paradigm. 2. fMRI mapping : Multi-slice functional images were obtained on a 1.5T Magnetom Vision MRI scanner (Simens Medical, Erlangen, Germany) equipped with high performance whole-body gradients. The BOLD T2 * - weighted images were acquired with acho planar imaging sequence (TR = 1.2 sec, TE = 60 msec, and flip angle = $90_{\circ}$). The other sequence parameter are : FOV = 210 mm, matrix=$64{\times}128$ or $64{\times}64$, slice number=10 and slice thickness = 5 or 8 mm. the anatomic images were obtained with Spin-echo T1-weighted images. The resulting images were then anaiyzed with STIMULATE (CMRR, U. of Minnesota) to generate functional maps using a student T-test (p < 0.005) and cluster analysis. Both positive and negative response were evaluated. Conclusions : We have observed the activation of the motor cortex by stimulating motor-related acupoint ($KI_6$). Among five subjects, negative BOLD response was shown in four and positive response in one. All subjects showed positive response to conventional finger flexion-extension task. To understand the detailed mechanisms of correlation between acupuncture stimulation and BOLD fMRI changes and two typs of response, further study strongly required.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.394-400
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• 2008

This paper presents an analytical method to investigate the stability of FDBs (fluid dynamic bearings) considering the tilting motion. The perturbed equations of motion are derived with respect to translational and tilting motion for the general rotor-bearing system with five degrees of freedom. The Reynolds equations and their perturbed equations are solved by using the FEM in order to calculate the pressure, load capacity, and the stiffness and damping coefficients. This research introduces the radius of gyration to the equations of notion in order to express the mass moment of interia with respect to the critical mass. Then the critical mass of FDBs is determined by solving the eigenvalue problem of the linear equations of motion. This research is numerically validated by comparing the stability chart of FDBs with the time response of the whirl radius obtained from the direct integration of the equations of motion. This research shows that the tilting motion is one of the major design considerations to determine the stability of rotating system. It also shows that the stability of FDBs considering only translation is overestimated in comparison with the stability of FDBs considering both translational and tilting motion.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.50-57
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• 2013

The high temperature thermal attacks in welding can affect the residual stress of a frame for automotive assembly accompanying frame deformation. Also the residual stress can induce the negative effect on durability performance of the automobile. In order to analyze the frame deformation, the simplified test frame which had the similar shape (form) of the real automotive frame was fabricated. The contactless optical 3D scanner was used for the shape difference measurement of the frame between before and after the welding. The FE-model of the test frame was composed and the deformation and residual stress simulation were performed. The simulated results were compared with the measured results for the reference of the frame design following as the variation of welding sequency. The deformation shape of the frame by simulation was in good agreement with that by the experimental measurement. In addition, the optimized welding sequency with reduced deformation after welding could be achieved through these analyses.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 추계종합학술대회
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• pp.277-279
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• 2003

본 논문은 단일 광원의 CIS에서 조도제어를 적용한 흑백 이미지 스케닝시스템 설계 및 구현에 관한 연구이다. 스케닝 방법은 이미지 스켄센서를 고정한 상태에서 스텝모터를 이용하여 스케닝 하고자 하는 문서를 이동하는 종이공급 방식을 사용하였다. 소형의 최적화된 시스템을 구현하기 위해 전용의 영상처리프로세서를 사용하여 시스템을 구성하였고, 센서를 통해 피딩 스텝마다 1라인의 스케닝된 입력된 데이터는 시스템 메모리에 저장된다. 스케닝을 시작하면 CIS 광원을 ON하여 스케닝하는 문서에서 반사되는 데이터를 수집하게 되는데, CIS 광원을 주기적으로 ON/OFF 하여 스케닝하고자 하는 문서의 조도를 제어하도록 하였다 스케닝 환경에 따라 조도를 제어함으로서 스케닝 이미지에서 적용전의 이미지에 비하여 PSNR이 0.3% 향상 되었다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.550-554
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• 1997

Acoustic or sound noise due to gradient pulsing has been one of the problems in MRI, both in patient scanning as well as in many areas of psychiatric and neuroscience research, such as unctional MRI (fMRI). Our recent observations in MRI or the visual and motor cortex show very different results with sound noise in comparison with the results obtained without sound noise. Although a number of ideas has been suggested in the literature about the possible elimination or reduction of sound noise, progress has been slow due to the basic role of gradient pulsing in MR imaging. Therefore, we report on some typical behavior of sound noise observed from MRI scanners and the analyses of their characteristics. Data are obtained both from a commercial MRI scanner (GE Signa 1.5-T EPI system).

• 한국자동차공학회논문집
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• 제19권5호
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• pp.113-117
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• 2011

The frame for automotive assembly can be deformed and remained on the residual stress due to high temperature thermal attacks when in welding. The frame deformation can be made to problems when in assembly with body and the residual stress can affect the negative effect on durability performance of the automobile. In order to analyze the frame deformation, the simplified test frame which had the similar shape (form) of the real automotive frame was fabricated. The contactless optical 3D scanner was used for the shape difference measurement of the frame between before and after the welding. The FE-model of the test frame was composed and the heat transfer and thermal stress simulation were performed. The simulated results were compared with the measured results for the reference of the frame design. The deformation shape of the frame by simulation was in good agreement with that by the experimental measurement.