• Journal of applied mathematics & informatics
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• 제7권1호
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• pp.279-287
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• 2000

A simple estimate of Feynman path-integration with general potential via its new definition is given and found to be very useful. This new method will help find the value of some Feynman path-integrals as precise as one wants.

• 한국유체기계학회 논문집
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• 제7권5호
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• pp.7-12
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• 2004

Multi-path ultrasonic flowrate measuring technology is being received much attentions from a variety of industrial fields to exactly measure the flowrate. Multi-path ultrasonic flowmeter has much advantage since it has no moving parts and little pressure loss. It offers good accuracy, repeatability, linearity and turn-down ratio can be over 1:50. The present study investigates flowrate integration errors using weighting factors. A theoretical flow model uses power law to describe a fully developed velocity profiles and wall roughness is changed. Gaussian, Chebyshev, and Tailor methods are used to integrate line-average velocities. The obtained results show that Chebyshev method in 2, 4-path arrangement and Gaussian method in 3, 5-path arrangement are not affected for wall roughness changes.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.370-377
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• 2002

Generally, the system of calculation for the multi-path ultrasonic flow meters can be divided into two methods by how to get the mean velocity, namely, weighting and direct method. Weighting-method derive the mean velocity through modeling in theoretical velocity profile. Direct-method derive the mean velocity though actual flow distribution. The system of calculation varies with maker's transducer configuration and integration method. Each system has merits and demerits. This paper describes the system of integration that calculates line velocity over cross-section of the circular pipe. Flow rate mr discussed in this paper is a difference between theoretical flow rate and integrated flow rate according to values of Reynolds number in symmetric flow field or theoretical flow rate and integrated flow rate according to rotated model in asymmetric flow field.

• 한국음향학회지
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• 제18권4호
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• pp.31-37
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• 1999

잡음환경에서 음성인식 시스템의 성능을 향상시키기 위해서 영상정보와 음성정보를 이용한 바이모달(bimodal)음성인식이 제안되어왔다. 영상정보와 음성정보의 결합방식에는 크게 분류하여 인식 전 결합방식과 인식 후 결합방식이 있다. 인식 전 결합방식에서는 고정된 입술파라미터 중요도를 이용한 결합방법과 음성의 신호 대 잡음비 정보에 따라 가변 입술 파라미터 중요도를 이용하여 결합하는 방법을 비교하였고, 인식 후 결합방식에서는 영상정보와 음성정보를 독립적으로 결합하는 방법, 음성 최소거리 경로정보를 영상인식에 이용 결합하는 방법, 영상 최소거리 경로정보를 음성인식에 이용 결합하는 방법, 그리고 음성의 신호 대 잡음비 정보를 이용하여 결합하는 방법을 비교했다. 6가지 결합방법 중 인식 전 결합방법인 파라미터 중요도를 이용한 결합방법이 가장 좋은 인식결과를 보였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.154-160
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• 2003

Multi-path ultrasonic flowrate measuring technology is being received much attentions from a variety of industrial fields to exactly measure the flowmeter. Multi-path ultrasonic flowmeter has much advantage since it has no moving parts and not occurred pressure loss. It offers good accuracy, repeatability, linearity and Tum-down ratio can measure over 1:50. The present study investigates flowrate integration errors using weighting factors. A theoretical flow model uses power law to describe a fully developed velocity profiles and wall roughness changes. The methods of weighting factor simulate three configurations of measuring location of gaussian, chebyshev and tailor method. The obtained results show that many chord arrangements are not affected for wall roughness changes and can measure accurate flowrate.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.1057-1058
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• 2008

In this paper, the algorithm and the computer simulation of a effective homing navigation system are presented. it is a combination of Path integration by using population coding and neural network and simple avoidance obstacle algorithm. Also, through the computer simulation, we demonstrated the feasibility of the suggested method.

• 로봇학회논문지
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• 제4권2호
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• pp.112-120
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• 2009

In this paper, a localization error recoverymethod based on bias estimation is provided for outdoor localization of mobile robot using different-type sensors. In the previous data integration method with DGPS, it is difficult to localize mobile robot due to multi-path phenomena of DGPS. In this paper, fault data due to multi-path phenomena can be recovered by bias estimation. The proposed data integration method uses a Kalman filter based estimator taking into account a bias estimator and a free-bias estimator. A performance evaluation is shown through an outdoor experiment using mobile robot.

• 대한전자공학회논문지TC
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• 제39권7호
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• pp.38-45
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• 2002

본 논문은 손실 매질 내에 매설된 선 전류 안테나에 의한 크기가 큰 완전도체 표적의 산란파를 해석하기 위한 전장적분식을 도출하였다. Sommerfeld 형태의 적분은 어떤 해석영역에 대하여 계산의 어려움과 제약들을 가지고 있으며, 많은 계산시간이 필요하다. 반면 최대 경사적분은 빠른 결과의 산출을 제공하였으며, 또한 그 계산 결과는 모든 해석 영역에 적용 가능하다. 임의의 완전도체 표적의 산란파는 최대경사적분법과 MOM 방법이 사용되었으며, 계산 결과는 가우시안 구적법과 GPOF 방법에 의해 비교되었다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.378-386
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• 2002

Multi-path ultrasonic Sow measurement system uncertainty is determined by assigning an expected error of each component of flow measurement and then defining the total flow measurement uncertainty as square root of the sum of squared values of the individual error. Sources of uncertainty for flow measurement are geometry, transit time and velocity profile integration uncertainty. A theoretical uncertainty model for multi-path ultrasonic transit time flowmeter configured with parallel 5 chords, is derived from and calculated by dry calibration method.

• 한국생산제조학회지
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• 제18권4호
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• pp.401-409
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• 2009

This paper presents a method of calculating the stress intensity factor (K) and crack propagation direction (${\theta}_0$) at the crack-tip that is associated with delamination in the large scale integration(LSI) package. To establish a reasonable strength evaluation method and life prediction, it is necessary to assess fracture parameters under various fracture conditions. Therefore, we conducted quantitative stress singularity analysis considering thermal stress simulating the changes of crack length (a), (h) and (v) in delamination using the 2-dimensional elastic boundary element method (BEM), and from these results predicted crack propagation direction and path.