• 대한기계학회논문집B
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• 제28권10호
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• pp.1271-1278
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• 2004

In order to measure non-intrusively velocity profile in liquid metal flow, a modified electromagnetic flowmeter was designed, which was based on electromagnetic tomography technique. Under the assumption that flow is fully-developed, axisymmetric and rectilinear, the velocity profile was reconstructed after the flowmeter equation, the first kind of Fredholm integration equation, was linearized. In reconstruction process Tikhonov regularization method with regularization parameter was used. The reconstructed velocity profile had the nearly same as turbulent flow profile which was approximately represented as log law. In addition, flowmeter output fur a fixed magnet rotation angle was linearly proportional to flow rate. When magnet rotation angle was 54$^{\circ}$, axisymmetric weight function was nearly uniform so that the flowmeter gives a constant signal for any fully-developed, axisymmetric and rectilinear profile with a constant flow rate.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.343-349
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• 1998

A modeling of machined geometry and cutting force was proposed for the case of round shape machining, and the effects of internally machined profile are analyzed and its realiability was verified by the experiments of roundness tester, especially in boring operation in lathe. Also, harmonic cutting force model was proposed with the parameter of specific cutting force, chip width and chip thickness, and in this study, we can see that bored workpiece profile was also mapped into cutting force signal with this model. In general, we can calculated the theoretical lobe profile with arbitrary multilobe. But in real experiments, the most frequently measured numbers are 3 and 5 lobe profile in experiments. With this results, we can predict that these results may be applied to round shape machining such as drilling, boring, ball screw and internal grinding operation with the same method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1375-1378
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• 1997

In this paper, we presents the algorithm which is to recognize the traffic sign on the road the traffic signal in a video image for autonomous navigation. First, the rocognition of traffic sign on the road can be detected using boundary point estimation form some scan-lines within the lane deducted. For this algorithm, index matrix method is used to detemine what sign is. Then, the traffic signal recognition is performed by usign the window minified by several scan-lines which position may be expected. For this algoritm, line profile concept is adopted.

• 조명전기설비학회논문지
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• 제27권7호
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• pp.52-58
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• 2013

The two-dimensional finite difference time domain algorithm is used to numerically reconstruct the electron density profile in O-mode ultrashort pulse reflectometry. A Gaussian pulse is employed as the source of a probing electromagnetic wave. The Gaussian pulse duration is chosen in such a manner as to have its frequency spectrum cover the whole range of the plasma frequency. By using a number of numerical band-pass filters, it is possible to compute the time delays of the frequency components of the reflected signal from the plasma. The electron density profile is reconstructed by substituting the time delays into the Abel integral equation. As a result of simulation, the reconstructed electron density profile agrees well with the assumed profile.

• The Journal of the Acoustical Society of Korea
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• 제15권4E호
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• pp.65-71
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• 1996

In shallow water with a thermocline, the characteristics of sound propagation strongly depend on the signal frequency. When only one of the source and the receiver is above the themocline, it is known that the intensity of the received signal changes largely and almost periodically as the signal frequency varies. This is the so-called channel resonance. By using the ray-mode approach, the formula relating the resonance frequency and the sound speed profile is obtained, and the resonance phenomenon is analyzed. Also this analysis is verified by numerical calculation.

• 한국통신학회논문지
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• 제41권12호
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• pp.1876-1883
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• 2016

본 논문에서는 고속의 공용데이터링크(common data link, CDL)를 위한 새로운 채널 모델을 제안한다. 송신기의 고도가 수km ~ 수십km이고 통달거리가 수백km인 경우 지구 곡률에 의해 송신신호가 수신기의 앞 쪽에서 지면에 반사되어 들어오는 Two-ray 채널이 발생할 가능성이 크다. 송수신기의 빔포밍(beamforming) 각도와 안테나 방사 패턴(radiation pattern)에 따라 반사 경로로 들어오는 신호의 최대 지연 시간(maximum delay)과 전력 지연 프로파일(power delay profile)을 추정하여 Two-ray 채널을 모델링한다. 제안하는 채널 모델에서는 통달거리가 길기 때문에 전력 지연 프로파일이 최대 지연 시간보다 신호 대 잡음비(signal to noise ratio, SNR)에 대한 비트 오류율(bit error rate, BER)에 더 큰 영향을 미친다.

• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.37-45
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• 1999

Many automated welding equipment are used in the industry. However, there are some problems to get quality welds because of the geometric error, thermal distortion, and incorrect joint fit-up. These factors can make the gap between base plates in case of a thick plate welding. The welding product with the quality welds can not be obtained without consideration of the gap. In this paper, the robot path and welding conditions are modified to get the quality weld by detecting the position and size of the gap. In this work, a low-priced laser range sensor is used. The 3-dimensional information is obtained using the motion of a robot, which holds a laser range sensor. The position and size of the gap is calculated using signal processing of the measured 3-dimensional information of joint profile geometry. The data measured by a laser range sensor is segmented by an iterative end point method. The segmented data is optimized by the least square method. The existence of gap is detected by comparing the data with the segmented shape of template. The effects of robot measuring speed and gap size are also tested. The recognizability fo the gap is verified as good by comparing the real joint profile and the calculated joint profile using the signal processing.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.263-266
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• 2002

An optical method for surface roughness estimation based on statistical analysis of the light intensity of a scattered laser beam pattern. The method is very simple but has a disadvantage that no more information than the averaged roughness is estimated. In this study a new try was conducted to derive more advanced surface information from the details of the light intensity distribution. Some periodic ripples among the light intensity distribution being assumed to relate with scratch left on the machined surface, a corresponding surface profile is estimated from the ripples using FFT and IFFT algorithm. IFFT technique is used to extract some dominant signal components among the intensity distribution. Compared to the measured profiles by a stylus type surf-tester, the profiles obtained through the proposed method are probably acceptable in a sense of the profile shape. Calibration of the amplitude needs more works in the future.

• 대한전기학회논문지
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• 제41권2호
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• pp.209-216
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• 1992

Deafs train articulation by observing mouth of a tutor, sensing tactually the motions of the vocal organs, or using speech training aids. Present speech training aids for deafs can measure only single speech parameter, or display only frequency spectra in histogram of pseudo-color. In this study, a speech training aids that can display subject's articulation in the form of a cross section of the vocal organs and other speech parameters together in a single system is to be developed and this system makes a subject know where to correct. For our objective, first, speech production mechanism is assumed to be AR model in order to estimate articulatory motions of the vocal organs from speech signal. Next, a vocal tract profile model using LP analysis is made up. And using this model, articulatory motions for Korean vowels are estimated and displayed in the vocal tract profile graphics.

• 한국공작기계학회논문집
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• 제17권1호
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• pp.106-112
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• 2008

In this paper, It does the profile measurement of the cam of diesel engine SOHC of the actual object. It uses the measurement of run-out method. This method is that the surface of the object is measured by the sensor when the object rotate, and calculated and displayed by the computer the signal which acquired by sensor. When we acquire the signals, we have two error because of motion and contacting between cam and probe. In this paper, we compensate the motion error while simply liner equation. And we have a solution that we change the figure of probe when we have a contacting error. We compared the data measuring on developed automatic cam profile measuring system with the data measured on CMM.