• 한국컴퓨터정보학회논문지
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• 제24권11호
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• pp.119-126
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• 2019

부분역최적화는 역최적화의 흥미로운 변형으로, 주어진 최적화문제와 그 문제의 부분해가 주어지면 이 부분해가 최적해에 포함되도록 문제를 최소한으로 수정하는 문제이다. 이 논문은 라인위에서 정의되는 순환외판원문제(TSP)를 다루는데, 이는 배달시스템, 창고 선반에서 물건을 수집하는 것, 등의 많은 응용을 가진다. 라인 위에서 위치하는 n개의 일이 주어지고 이 중 연속적으로 처리해야하는 일 k개가 부분적으로 주어진다. 각각의 일은 라인 위의 특정 장소에 위치하고 라인을 움직이는 서버에 의해 처리되어야 한다. 우리의 임무는 k개의 일이 최적해에서 연속적으로 처리되도록 n개의 일의 위치를 라인 위에서 최소한으로 조정하는 것이다. 이 논문에서 이 문제와 이 문제의 다양한 변종을 다항시간 내에 푸는 알고리즘을 개발한다. 구체적으로, 서버가 특정한 Forward Trip이라는 특정한 내부 알고리즘을 사용하는 경우와 일반적인 최적 알고리즘을 사용하는 경우에 대한 부분역최적화를 다룬다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.2809-2811
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• 1999

In this paper, we develope an algorithm to calculate field inhomogeneity in MR imaging using a dual fast spin echo pulse sequence. Because phase modulation time can be easily modified with this pulse sequence, high resolution image can be obtained and acquisition time can be reduced compared to gradient echo technique. In the case of phase wrapping in field map, phase corrected using image processing technique. We assume the field pattern to be second order polynomial and apply Pseudo-Inverse equation to calculate second order polynomial coefficients. These coefficients can be used for the shimming of the magnetic field.

• Earthquakes and Structures
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• 제2권4호
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• pp.323-336
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• 2011

The problem of reconstruction of complete building response from a limited number of response measurements is considered. The response at the intermediate degrees of freedom is reconstructed by using piecewise cubic Hermite polynomial interpolation in time domain. The piecewise cubic Hermite polynomial interpolation is preferred over the spline interpolation due to its trend preserving character. It has been shown that factorization of response data in variable separable form via singular value decomposition can be used to derive the complete set of normal modes of the structural system. The time domain principal components can be used to derive empirical transfer functions from which the natural frequencies of the structural system can be identified by peak-picking technique. A reduced-rank approximation for the system flexibility matrix can be readily constructed from the identified mass-orthonormal mode shapes and natural frequencies.

• 한국위성정보통신학회논문지
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• 제3권1호
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• pp.15-21
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• 2008

OFDM (직교 주파수 분할 다중화) 신호의 높은 PAPR은 시스템의 송신단에서 전력증폭기의 비선형적 특성으로 인해 비선형 왜곡이 불가피하게 발생한다. 이 현상은 대역 내 왜곡과 대역 외 방사를 초래한다. 본 논문에서는 다항식 (polynomial) 모델에 기반한 사전왜곡(pre-distortion) 기법으로 이러한 문제를 보상하는 기법을 제안한다. 비선형 및 역비선형 다항식 모델 추정은 LSE(Least Square Error) 알고리즘으로 수행한다. 또한 시스템의 성능 향상을 위해 피크제거와 클리핑 결합기법을 이용해 OFDM 신호가 전력증폭기의 포화 영역 근처에서 동작함으로써 발생하는 왜곡된 신호의 진폭을 제거한다.

• Structural Engineering and Mechanics
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• 제60권3호
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• pp.455-470
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• 2016

In this paper, we investigate the free vibration of axially loaded non-uniform Rayleigh cantilever beams. The Rayleigh beams account for the rotary inertia effect which is ignored in Euler-Bernoulli beam theory. Using an inverse problem approach we show, that for certain polynomial variations of the mass per unit length and the flexural stiffness, there exists a fundamental closed form solution to the fourth order governing differential equation for Rayleigh beams. The derived property variation can serve as test functions for numerical methods. For the rotating beam case, the results have been compared with those derived using the Euler-Bernoulli beam theory.

• Journal of Mechanical Science and Technology
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• 제16권10호
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• pp.1320-1326
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• 2002

In a one-dimensional heat conduction domain with heated and insulated walls, an integral approach is proposed to estimate time-dependent boundary heat flux without internal measurements. It is assumed that the expression of the heat flux is not known a priori. Hence, the present inverse heat conduction problem is classified as a function estimation problem. The spatial temperature distribution is approximated as a third-order polynomial of position, whose four coefficients are determined from the heat fluxes and the temperatures at both ends at each measurement. After integrating the heat conduction equation over spatial and time domain, respectively, a simple and non-iterative recursive equation to estimate the time-dependent boundary heat flux is derived. Several examples are introduced to show the effectiveness of the present approach.

• 대한기계학회논문집B
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• 제31권9호
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• pp.764-771
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• 2007

The objective of the present work is to evaluate the evaporation heat flux of deposited droplet on the hot surface by using of inverse heat transfer technique. On the basis of measured temperature, a integral form solution is determined for the transient temperatures beyond the two positions by using Green's function technique. This method first approximates the temperature data with a half polynomial series of time. we compared this result with constant radius model in single phase regime, nucleate boiling regime, film boiling regime respectively. this paper performed the experiments as following conditions: (a)the surface temperature is within the range between $80^{\circ}C\;and\;160^{\circ}C$ in the conduction, (b) droplet diameter are 2.4 and 3.0mm. (c) surface roughness is $0.18{\mu}m$.

• 대한수학회지
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• 제57권6호
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• pp.1535-1549
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• 2020

This paper deals with the inverse of tails of Hurwitz zeta function. More precisely, for any positive integer s ≥ 2 and 0 ≤ a < 1, we give an algorithm for finding a simple form of f_s,a(n) such that $$\lim_{n{\rightarrow}{\infty}}\{\({\sum\limits_{k=n}^{\infty}}{\frac{1}{(k+a)^s}}\)^{-1}-f_{s,a}(n)\}=0$$. We show that f_s,a(n) is a polynomial in n-a of order s-1. All coefficients of f_s,a(n) are represented in terms of Bernoulli numbers.

• KIEE International Transaction on Systems and Control
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• 제2D권2호
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• pp.53-58
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• 2002

In this paper, various aspects in magnetoencephalography (MEG) source localization are studied. To minimize the errors in experimental data, an approximation technique using a polynomial function is proposed. The simulation shows that the proposed technique yields more accurate results. To improve the convergence characteristics in the optimization algorithm, a hybrid algorithm of evolution strategy and sensitivity analysis is applied to the neuromagnetic inverse problem. The effectiveness of the hybrid algorithm is verified by comparison with conventional algorithms. In addition, an artificial neural network (ANN) is applied to find an initial source location quickly and accurately. The simulation indicates that the proposed technique yields more accurate results effectively.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.539-544
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• 1991

In order to verify robot motions for a desired work, it is necessary to visualize it on a computer screen. This paper presents a simulation algorithm for robot manipulator motion. Kinematic description is based on the Denavit- Hartenberg link representation. In order to be applied to various types of the robot manipulator, inverse kinematics make use of the Newton-Raphson iterative method with the least squares method. Joint variables are interpolated by the lowest polynomial segment satisfying acceleration continuity. The robot motions are generated and then animated on a computer screen in the form of skeleton type.