• East Asian mathematical journal
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• 제31권4호
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• pp.609-625
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• 2015

This study was subjected to 9th graders after making a conformity analysis about errors in function from a selected linear function domain learned in 8th grade, and using this we analyzed some errors learners have in the linear function domain. Learners showed the most deficiency in mastery of prerequisite facts concepts out of errors in linear functions and lack of skill in interpreting the content of the questions and technical errors occurred often as well. How the pre-service secondary school teachers prescribed these errors of linear function was analyzed from the point of problem solving strategies, accessing methods and whether or not the learner's error was used. Looking into the pre-service secondary teachers' prescription of the learners' errors in 3 fields, for the problem solving strategy a procedural strategy was used more than a conceptual strategy, and as for the accessing methods over 90% gave teacher led type explanations to the students. Also over 90% of pre-service secondary teachers did not use the learner's errors that turned up in problems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1-6
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• 2003

This paper considers the problem of determining a set of stabilizing first order controller gains, for a given linear time invariant plant, that meets or exceeds closed loop step response specifications. The method utilizes two recent results: For a given system, (1) finding a set of stabilizing first order controller gains and (2) the relationship between time response (overshoot and speed) and the coefficients of the characteristic polynomial. The method allows us to extract a subset of first order controller gains that meets stability as well as time domain performance requirements. The computations involved are the intersections of two dimensional sets described by linear and quadratic inequalities in the controller design space. It is illustrated by examples.

• 한국지능시스템학회논문지
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• 제14권2호
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• pp.247-252
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• 2004

In this paper are proposed 2nd-order PD-type iterative learning control algorithms for linear continuous-time system and linear discrete-time system. In contrast to conventional methods, the proposed learning algorithms are constructed based on both time-domain performance and iteration-domain performance. The convergence of the proposed learning algorithms is proved. Also, it is shown that the proposed method has robustness in the presence of external disturbances and the convergence accuracy can be improved. A numerical example is provided to show the effectiveness of the proposed algorithms.

• The Journal of the Acoustical Society of Korea
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• 제27권1E호
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• pp.11-16
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• 2008

In this paper, a pitch cycle waveform (PCW) is extracted, quantized, and interpolated in a time domain to synthesize high-quality speech at low bit rates. The pre-alignment technique is proposed for the accurate and efficient PCW extraction, which predicts the current PCW position from the previous PCW position assuming that pitch periods evolve slowly. Since the pitch periods are different frame by frame, the original PCW is converted into the fixed-dimension PCW using the dimension-conversion method, and subsequently quantized by code-excited linear predictive (CELP) coding. The excitation signal for the linear predictive coding (LPC) synthesis filter is generated using the time-domain interpolation and interlink of the quantized PCW's. The coder operates at 4.2 kbit/s and 3.2 kbit/s depending on the pitch period. Informal listening test demonstrates the effectiveness of the proposed coding scheme.

• 로봇학회논문지
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• 제2권2호
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• pp.183-190
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• 2007

The most important thing for navigation of a mobile robot is to find the most suitable path and avoid the obstacles in the static and dynamic environment. This paper presents a method to search the optimal path in start space extended to time domain with considering a velocity and a direction of moving obstacles. A modified version of $A^*$ algorithm has been applied for path planning in this work and proposed a method of path search to avoid a collision with moving obstacle in space-tim domain with a velocity and an orientation of obstacles. The velocity and the direction for moving obstacle are assumed as linear form. The simulation result shows that a mobile robot navigates safely among moving obstacles of constant linear velocity. This work can be applied for not only a moving robot but also a legged humanoid robot and all fields where the path planning is required.

• 한국해양공학회지
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• 제20권4호
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• pp.70-75
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• 2006

A numerical procedure is described for estimating the effects of the multi-directional irregular waves on the motion responses and tension variations of the ISSC-TLP. The numerical approach is based on a three-dimensional source distribution method and a spectral analysis technique of directional waves. The spectral description for the linear system of ISSC-TLP in the frequency domain is sufficient to completely define the motion responses and tension variations. This is because both the wave inputs and responses are stationary Gaussian random processes, of which the statistical properties in the amplitude domain are well known. The numerical results for the linear motion responses and tension variations in regular waves are compared with the experimental and numerical ones, which are obtained in the literature. The results of comparison confirmed the validity of the proposed approach.

• 자원환경지질
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• 제18권1호
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• pp.41-47
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• 1985

Hankel변환적분의 계산에 사용되는 $J_0$ 및 $J_1$ 디지탈 선형필터의 성능을 adaptive 필터를 사용함으로써 비교 하였다. $J_0$ 영역의 어떠한 Hankel 변환적분도 수학적으로 이에 대응하는 $J_1$ 영역으로 바꿀 수 있으며, 비저항 탐사에서 이용되는 모든 전극배치에 대한 겉보기비저항은 $J_1$ 필터만으로 계산이 가능하다. 보통 $J_1$ 필터는 이와 대응하는 $J_0$필터에 비하여 정확성은 비슷하지만, 계산효율은 좀 더 높다. 또한 $J_0$에서 $J_1$영역으로 변환시키면, Schlumberger배치 뿐만 아니라 쌍극자배치 사용시에도 $J_1$함수만을 포함하는 효율적인 겉보기비저항 계산식을 이용할 수 있다.

• 영재교육연구
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• 제13권4호
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• pp.119-140
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• 2003

이 연구의 목적은 초·중·고등학교의 교육현장에서 창의성의 영역성이 어떻게 나타나는가를 실증적으로 검증하는 것이다. 연구대상을 전체학생 집단, 고창의성 집단, 저창의성 집단의 3개 집단으로 구분하여 각 집단에서의 영역성을 비교 규명하는 것이다. ‘능력-분화가설’에 기초하여, 4개 영역간의 상관관계, 영역-일반성의 변인과 영역-특수성의 영역간의 상관관계, 그리고 영역-특수성에 대한 영역-일반성의 상대적 예측력을 분석하였다. 연구결과, 연구가설과는 오히려 반대의 결과가 나타났다. 즉, 저창의성 집단에서는 영역-특수성을 지지하였으나, 전체학생과 고창의성 집단에서 영역-일반성과 영역-특수성의 어느 한쪽을 일방적으로 지지하기 어려운 결과가 나타났다. 오히려 영역-일방성과 영역-특수성이 상호 보완 또는 통합되는 영역-상보설이 지지되었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제3권1호
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• pp.86-94
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• 2011

This paper compares frequency domain and time domain predictions from the ShipMo3D ship motion library with observed motions from model tests and sea trials. ShipMo3D evaluates hull radiation and diffraction forces using the frequency domain Green function for zero forward speed, which is a suitable approach for ships travelling at moderate speed (e.g., Froude numbers up to 0.4). Numerical predictions give generally good agreement with experiments. Frequency domain and linear time domain predictions are almost identical. Evaluation of nonlinear buoyancy and incident wave forces using the instantaneous wetted hull surface gives no improvement in numerical predictions. Consistent prediction of roll motions remains a challenge for seakeeping codes due to the associated viscous effects.

• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.55-62
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• 2015

In this study we demonstrate ultrahigh-resolution spectral domain optical coherence tomography (UHR SD-OCT) with a linear-wavenumber (k) spectrometer, to accelerate signal processing and to display two-dimensional (2-D) images in real time. First, we performed a numerical simulation to find the optimal parameters for the linear-k spectrometer to achieve ultrahigh axial resolution, such as the number of grooves in a grating, the material for a dispersive prism, and the rotational angle between the grating and the dispersive prism. We found that a grating with 1200 grooves and an F2 equilateral prism at a rotational angle of $26.07^{\circ}$, in combination with a lens of focal length 85.1 mm, are suitable for UHR SD-OCT with the imaging depth range (limited by spectrometer resolution) set at 2.0 mm. As guided by the simulation results, we constructed the linear-k spectrometer needed to implement a UHR SD-OCT. The actual imaging depth range was measured to be approximately 2.1 mm, and axial resolution of $3.8{\mu}m$ in air was achieved, corresponding to $2.8{\mu}m$ in tissue (n = 1.35). The sensitivity was -91 dB with -10 dB roll-off at 1.5 mm depth. We demonstrated a 128.2 fps acquisition rate for OCT images with 800 lines/frame, by taking advantage of NVIDIA's compute unified device architecture (CUDA) technology, which allowed for real-time signal processing compatible with the speed of the spectrometer's data acquisition.