• 한국초전도ㆍ저온공학회논문지
• /
• 제17권3호
• /
• pp.28-32
• /
• 2015

Nowadays the magnetic field mapping is widely used in the design and analysis of the NMR/MRI magnet system, and the accuracy of mapping result has become more and more important. There are several factors affecting the accuracy of the mapping such as the mapping method, the precision of the sensor, the position of the measurement points, the calculation accuracy, and so on. In this paper the error due to the misalignment of the measurement points was discussed. The magnetic field in the central volume was mapped using an indirect method in an MRI magnet system and the magnetic field was fitted to a polynomial. Considering the misalignment between the original measurement points and the practical measurement points, there must be some errors in the mapping calculation and we called it positioning error. Several comparisons of the positioning error have been presented through the theoretical estimates and the exact magnetic field values. Finally, the allowable positioning errors were suggested to guarantee the accuracy of the magnetic field mapping within a certain degree for an example case.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.1326-1333
• /
• 2006

Purpose of this research is a development for the curve fitted equations that can improve practical calculation and work application when seismic performance has been evaluated and this work has been made a study of the dynamic response under various boundary conditions of buried pipelines to compare the dynamic behavior of concrete pipe and steel pipe, FRP pipe. This research have been developed curve fitted equations that can be improving efficiency and practicality. Using a nonlinear least square method, and after testing several different exponential equations, Proposed the curve fitted equations to give the best result and constant value by the propagation velocities. With these results, dynamic response analysis and seismic performance evaluation have been achieved on concrete pipe, steel pipe and FRP pipe that have a various boundary conditions. Degree of a polynomial expression and coefficient value by propagation velocity have been calculated when using the curve fitting equations.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.572-581
• /
• 2006

This study is to investigate dynamic response of concrete buried pipelines with various end boundary conditions and develop a curve fitted equation to ensure practicality and convenience for the use at the actual field for the test of resistance of earthquake. Dynamic response under the various end boundary conditions is calculated with analysis on values and computing programs. However, such a method of analysis requires skillfulness in using computing programs for dynamic movement of buried pipelines with dynamic analysis formula and has lower efficiency and practicality because, in the nature of analysis program of values, it needs much time to conduct repeated calculations. Therefore, the study is intended to develop a curve fitted equation to ensure more efficient and practical analysis. This paper tests various degrees of equation with non-linear least square method and developments a curve fitted equation based on the transmission speed with the best results. In the use of curve fitted equation, degree of polynomial and determining coefficient are influenced by the speed of transmission.

• The Korean Journal of Ecology
• /
• 제10권3호
• /
• pp.119-127
• /
• 1987

On the east slope of the front ranges of the Colorado Rockies, USA, three species of Populus are distributed at different elevations from the Great Plains to the timberline. At elevations 1, 720m (P. sargentii), 2, 335m (P.angustifolia) and 3, 190m (P.tremuloides) chlorophyll cotents of leaves of thses dioecious trees were determined. Total chlorophyll content was in the range of 0.86-1.56mg/g leaf, increasing with elevation as a second-degree polynomial, and the peak content was estimated to be reached at about 2, 800m. Total chlorophyll content was greater in female than in male trees in the two higher elevation species, but not in P. sargentii, the low elevation species. Chlorophyll b content was greater than chlorophyll a content in the same two higher elevation species. The increase of chlorophyll b than to increase of chlorophyll a content. These phenomena appear to be the result of adaptation of these species to different environmental conditional at different elevation. Sequential distribution of plant populations on environmental gradients in such a way that variation in given plant characters paralell the environmental gradient must occur not only in ecotypes of a species, but also in different but closely related species.

• 대한토목학회논문집
• /
• 제13권2호
• /
• pp.151-160
• /
• 1993

본 논문에서는 Reissner-Mindlin 평판이론에 근거한 계층적 $C^{\circ}$-평판요소가 제안되었다. 적분형 르장드르 형상함수에 근거한 계층요소를 제안하는 이유는 종래의 h-version 유한요소법의 개념 을 사용하여 전단구속 효과등에 대한 해의 정확도 및 수치안정성을 확보할 수 있는 요소를 만드는데 여전히 어려움이 수반되기 때문이다. 적응적 체눈 p-세분화와 선택적 형상함수 차수 p의 분포를 사용하는 hp-version 유한요소법을 사용하여 내부주변은 자유단의 개구부를 갖고, 외부주변이 단순지지된 L-형 평판해석을 수행하였는데 종래의 h-version 유한요소법에 비해 우월한 수렴성과 전단구속을 피할 수 있는 등의 알고리즘 효율성을 보여 주고 있다.

• 전자공학회논문지SC
• /
• 제43권6호
• /
• pp.40-47
• /
• 2006

본 논문은 CRC 회로의 성능을 향상시키기 위하여 파이프라인 구조를 적용한 병렬 CRC 회로 설계 방법을 제시한다. 입력 데이터의 폭이 CRC 다항식의 차수보다 큰 병렬 CRC 회로를 파이프라인 구조로 변형하기 위하여 로직을 분할하고 파이프라인 단계의 길이를 결정하고, 각 파이프라인 단계에 레지스터를 삽입하는 알고리즘을 제시한다. 여러 가지 타입의 병렬 CRC 회로에 대해, 본 논문에서 제안한 방식이 현저하게 성능을 향상 시켰음을 알 수 있다.

• 대한수학회논문집
• /
• 제9권2호
• /
• pp.467-489
• /
• 1994

Let $\Omega$ be a closed and bounded polygonal domain in R$^2$, or a closed line segment in R$^1$ with boundary $\Gamma$, such that there exists an invertible mapping T : $\Omega$ \longrightarrow $\Omega$ with the following correspondence: x$\in$$\Omega$ ↔ x = T(x) $\in$$\Omega$, (1.1) and (1.2) t $\in$ U$\sub$p/($\Omega$) ↔ t = to T$\^$-1/ $\in$ U$\sub$p/($\Omega$), where $\Omega$ denotes the corresponding reference elements I = [-1,1] and I ${\times}$ I in R$^1$ and R$^2$ respectively, (1.3) U$\sub$p/($\Omega$) = {t : t is a polynomial of degree $\leq$ p in each variable on $\Omega$}, and (1.4) U$\sub$p/($\Omega$) = {t : t = to T $\in$ U$\sub$p/($\Omega$)}.(omitted)

• Natural Product Sciences
• /
• 제24권1호
• /
• pp.71-78
• /
• 2018

The present study deals with the determination of optimal values of operating parameters such as the temperature of heating, the mass of the plant material and the volume of water leading to the best yield of electromagnetic induction (EMI) heating extraction of Algerian Thymus fontanesii essential oil. After an appropriate choice of the three critical variables, eight experiments leaded to a mathematical model as a first-degree polynomial presenting the response function (yield) in the relation to the operating parameters. From the retained model, we were able to calculate the average response, the different effects and their interactions. The maximum of essential oil recovery percentage relative to the initial mass of plant material was 1.69%, and was obtained at ($140^{\circ}C$, 250 g and 4.5 L). The chemical composition of the Algerian T. fontanesii essential oil under the obtained optimal conditions ($140^{\circ}C$, 250 g and 4.5 L), determined by GC/MS and GC/FID, reveled of the presence of major components such as: carvacrol ($70.6{\pm}0.1%$), followed by p-cymene ($8.2{\pm}0.2%$).

• 한국농공학회지
• /
• 제43권3호
• /
• pp.85-93
• /
• 2001

In this study, a computer program considering shape imperfections of arch under dynamic loading was developed. The shape imperfection of arch was assumed as higher degree polynomial expressed as $\omega$$_{i}$ = $\omega$$_{o}$ (1-(2$\chi$/L)$^{m}$ )$^n$and sinusoidal curve such as $\omega$$_{i}$ = $\omega$$_{o}$ sin(η$\pi$$\chi$/L). In finite element formulation, the material nonlinear behavior was assumed the elasto-viscoplastic model highly corresponding to the real behavior of the material and the geometrically nonlinear behavior was modeled using Lagrangian description of motion. Also, the behavior of steel was modeled by applying yield criteria of Von Mises. The developed program was applied to the analysis of the dynamic behavior for the clamped beam subjected to the concentrated load at midspan and the results were compared with those from other research to investigate accuracy of the presented finite element program. In numerical examples, the shape imperfections of L/500, L/1,000 and L/2,000 were considered and the modes of shape imperfections of the symmetric and antisymmetric were adopted. The effects of the shape imperfections on the dynamic behavior of arch were conspicuous and results of analysis indicate that the reasonable values of arch rise to arch span ratio ranged between 0.1 and 0.3.

• 한국농공학회논문집
• /
• 제62권1호
• /
• pp.61-70
• /
• 2020

To estimate the ventilation volume of mechanically ventilated swine farms, various regression models were applied, and errors were compared to select the regression model that can best simulate actual data. Linear regression, linear spline, polynomial regression (degrees 2 and 3), logistic curve, generalized additive model (GAM), and gompertz curve were compared. Overfitting models were excluded even when the error rate was small. The evaluation criteria were root mean square error (RMSE) and mean absolute percentage error (MAPE). The evaluation results indicated that degree 3 exhibited the lowest error rate; however, an overestimation contradiction was observed in a certain section. The logistic curve was the most stable and superior to all the models. In the estimation of ventilation volume by all of the models, the estimated ventilation volume of the logistic curve was the smallest except for the model with a large error rate and the overestimated model.