The Computer Algebra Systems in Mathematics Education : A Review of Recent Research

Kwon, Oh-Nam,Shin, Eun-Ju,Shon, Bo-Kyung 이화여자대학교 교과교육연구소 2001 East west education Vol.18 No.-

This study examines the potential role for Computer Algebra Systems(CAS) in such an educational context, particularly their potential to get students more engaged in the learning of mathematics as well as to reduce the "strangle hold" of prerequisite algebraic skills, in courses such as functions, introductory calculus. What is the present status of and near-future outlook for computer algebra in Korean secondary schools? The answer that arises from this review of available fact is: bright with promise, but still dim. Several recent developments have set the stage for an acceleration in the dissemination rate for CAS to high schools. However, this review of some past and present conditions indicates that many years will pass before computer algebra is impacting high school mathematics as much as hand-held calculators are doing now.

블루투스 시스템의 기술 분석

권오신,이충기 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

The Bluetooth system is a short distance wireless data communication standard that European mobile communication terminal companies get into main axis. This technology is developed by a SIG whose members are more than 2000. Devices of the system can transmit signals at the speed of 1 Mbps from 10 m to 100m using 2.4 GHz frequency. We investigate the protocol stack of the Bluetooth system as well as its main features. Then, we identify several problems of the system.

淸溪山 落葉松林의 林床草本 群叢에 對한 種相關에 관하여

權五溶,辛昌男,鄭會台 충남대학교 자연과학연구소 1983 忠南科學硏究誌 Vol.10 No.2

The study of the herbaceous species association in the larch forest of Mt. Chungkyeu was carried out from April to October, 1980. 1. The herbaceous ground association was consist of 43 species, Oplismenus undulatifolius, Festuca ovina, Oalamagrostis arundinaceae var. brachytricha and Carex pediformis var. rhizina were dominant species. 2. The major herbaceous species, of which important value was above 10, were Oplismenus undulatifolius(28.2%), Festuca ovina(26.7%), Miscanthus purpurascens(26.5%), Calamagrostis arundinaceae var. brachytricha(21.2%), Carex nanella(17.5%), Carex lanceolata(15.4%), Carex pediformis var. rhizina(14.1%), Carex siderosticta(12.7%), Potentilla fragarioides(11.7%) and Artemisia keiskeana(10.5%). 3. Classifying the herbaceous ground association by partial ordination, it was divided into two kinds of association ; Carex-Oplismenus association and Calamagrostis-Oplismenus association. 4. The results of the species association analysis was the same as the ordination. The coefficients of species exhibited the positive value in the same association, on the contrary, it was negative value in the different association.

미분없는 칼만필터 학습 알고리즘을 이용한 순환신경망의 파라미터 추정

권오신 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-

Recurrent neural network(RNN) trained with gradient based such as real time recurrent learning has a drawback of slow convergence rate. This algorithm also needs the derivative calculation which is not trivialized in error back propagation process. In this paper a derivative free Kalman filter for training a fully connected RNN is presented in a state space formulation of the system. A derivative free Kalman filter learning algorithm makes the RNN have fast convergence speed and good tracking performance without the derivative computation. Through experiments of nonlinear channel equalization, performance of the RNN with a derivative free Kalman filter algorithm is evaluated.

결찰양식이 교정용 브라켓과 교정선 사이의 마찰력에 미치는 영향

신현정,권오원,김교한 대한치과교정학회 1998 대한치과교정학회지 Vol.28 No.5

마찰력은 치아이동시 활주이동부에 유해한 인자로 인식되어져 왔으나 치아이동에 저항하는 고정원에 있어서는 유리한 인자로 받아들여질 수 있다. 즉 마찰력이 작은 결찰법들을 이용하여 효과적인 치아이동을 도모하는 반면 마찰력이 큰 결찰법들을 이용하여 브라켓의 걸림에 의해 치아이동이 거의 일어나지 않게 하면 고정원을 강화할 수 있다. 인공타액하에서 시간경과에 따른 교정선과 브라켓 사이의 마찰력 변화, 탄성 모듈과 스테인레스 강 결찰선을 이용하여 각각 결찰양식을 달리 하였을 때의 마찰력 변화 그리고 결찰재의 내료를 달리 하였을 때의 마찰력 변화를 알아보기 위하여 .018" ×.025" 슬롯의 상악 중절치용 standard edgewise twin 브라켓과 .017" ×.022" 스테인레스 강 교정선을 탄성 모듈, .009" 스테인레스 강 결찰선 그리고 .012" 스테인레스 강 결찰선을 이용하여 다양하게 결찰하였다. 또한 통상적인 방법으로 결찰한 탄성 모듈 결찰군을 결찰 직후와 1주 간격으로 4주간 마찰력을 측정하여 다음과 같은 결과를 얻었다. ·탄성 모듈 whole tie시 시간경과에 따른 마찰력은 4주 경과시 가장 높았으나 3주, 2주, 1주, 결찰 직후간에는 통계학적으로 유의한 차이가 없었다(P>0.05). ·탄성 모듈로 결찰시 마찰력은 twisting tie가 가장 높았고 double overlay tie, whole tie, half tie 순으로 나타났으나 twisting tie와 double overlay tie 간에는 통계학적으로 유의한 차이가 없었다(P>0.05). ·스테인레스 강 결찰선으로 결찰시 half tie 군이 whole tie 군보다 낮은 마찰력을 보였으며 ligature tying plier로 결찰한 경우가 needle holder로 결찰한 경우보다 더 높았고 .012" 결찰선을 이용한 경우가 .009" 결찰선을 이용한 경우보다 더 높았다(P<0.05). ·통상적인 방법으로 탄성 모듈과 스테인레스 강 결찰선을 이용하여 결찰한 경우 두 군간에 유의한 차이가 없었다(P>0.05). The frictional force has been considered as an harmful factor in an active unit where tooth movement occurs, but as an advantageous factor in anchor unit that resist tooth movement. That is, efficient tooth movement is planned by using ligation methods that have low levels of bracket-wire frictional force and the anchorage control can be achieved by using ligation methods that have high levels of bracket-wire frictional force that result in binding of the bracket accompanied by little or no tooth movement. The purpose of this study was to evaluate the frictional force generated between bracket and wire in accordance with the methods of ligation, the material of ligation and the passage of time under artificial saliva. Tested were 0.017×0.022inch stainless steel wires in standard edgewise twin brackets for upper central incisors in a 0.018-inch slot. The wires were ligated into the brackets with elastomeric modules and stainless steel ligatures. Whole tie, half tie, twisting tie and double overlay tie were done with elastomeric modules. With 0.009-inch stainless steel ligature whole tie and half tie were done by needle holder and whole tie by ligature tying plier. With 0.012-inch stainless steel ligature whole ties were done by needle holder. Whole tie groups of elastomeric module were kept in artificial saliva bath at 37℃ for 28 days. The frictional force was recorded by means of an Instron universial testing instrument (4202 INSTRON, Instron Co., U.S.A.) at initial, 7, 14, 21, and 28 days. The results for ligated samples in a simulated oral environment revealed the following: ·In elastomeric module whole tie, 28days group was significantly greater mean static frictional force than any other group but there were no significant differences among any other group (p>0.05). ·Elastomeric module twisting tie were significantly greater mean static frictional forces than any other ligation method but there were no significant differences between twisting tie and double overlay tie(p>0.05). Twisting tie, double overlay tie, whole tie, half tie showed differences in decreasing order. ·Stainless steel half tie produced lower mean static frictional force than whole tie, ligature tying plier produced greater mean static frictional force than by needle holder and ligation with 0.012-inch stainless steel ligature produced greater mean static frictional force than with 0.009-inch stainless steel ligature (p<0.05). ·There were no significant differences between the mean static frictional forces of elastomeric whole tie and stainless steel whole tie (p>0.05).

Pinus koraiensis와 Pinus parviflora의 樹高에 따른 氣孔數 變異에 關하여

權五容,辛昌男,吳炅煥,方在旭 충남대학교 자연과학연구소 1980 學術硏究誌 Vol.7 No.2

Stomata1 distribution in relation to the height of Pinus parviflora and Pinus koraiensis was studied 1. Stomata1 bands per needle of P parviflora and P koraiensis were 8.60±0.62 - 11.47±0.74, 14.07±1.03 - 16.60±0.99 and the number of stomata per band were 382.0±8.80 404.27±26.16, 1,326. 67±87.78 - 2,286.58±214.57, respectively 2. The number of stomatal band was significantly different between 3, 4m and 5, 6m in P parviflora and between 5, 6m and 7m in P. koraiensis Consequently, it is suggested that stomatal frequency gradient associated with increasing height above the ground is correlated with the greater degree of exposure to light.

CFRP 판재의 섬유방향에 따른 절삭성 평가

신봉철,하석재,강민형,권오양,조명우 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

In recent, the CFRP(Carbon Fiber Reinforced Plastics) composite has been widely used because it has light-weight and high mechanical strength. Therefore, CFRP composite is applied to variable industrial areas such as aerospace, automobiles, sporting goods, ships and so on. Generally, CFRP composite has been used in the industrial field by mechanical cutting processes. In this research, the CFRP composite specimen are laminated by 64plies with orientation angles such as 0°, 45°, 90° and [0°/±45°/90°]4S. The results are analyzed with cutting force and cutting surface.

소자 모의를 이용한 OTA-C 필터 설계

권오신 群山大學校自然科學硏究所 1989 自然科學硏究 Vol.4 No.-

Systematic procedure is presented for the design on OTA(Operational Transconductance Amplifier)-C filters obtained as inductor and resister simulations from LC ladder prototype. Design examples are presented for 5-th order chebyshev filter and a method of reducing the number of active element required is outlined.

주파수 영역에서 선형시스템의 새로운 간략화법

權五臣 群山大學校自然科學硏究所 1990 自然科學硏究 Vol.5 No.-

M.F. Hutton과 B. Friedland 또는 S.v. Rao가 제시한 Routh 간략화법은 연분수 전개하여 alpha-beta 또는 gamma-delta표에 의하여 계수를 구한 후 필요한 차수 이외의 항을 제거한 다음 역으로 유리화시키는 방법을 취하였기에 그 과정이 대단히 불편하였다. 본 논문에서 제시한 새로운 시스템 간략화법은 Routh 간략화법에서 지적되는 연분수 전개식을 사용하지 않고 계산이 간단한 새로운 방법을 제시하였다. 간략화 모델의 분모다항식은 Schwarz의 D-table을 이용하여 표에서 바로 읽어, 구할 수 있고, 분자다항식은 Pade 간략화법에서 사용한 멱급수 전개방식을 응용하는 기법을 사용하여 구했다. 본 논문의 특징은 원 시스템이 안정하면 간략화 모델 역시 반드시 안정하며 간략화 과정에서 Routh의 간략화 방법에 비하여 계산이 간단함을 들 수 있겠다. 앞으로 다변수계(Multivariable Input/Output System)와 시변계(Variant System)에 대하여 본 논문의 간략화법의 적용방법은 더욱 연구되어야 할 과제이다. A freguency domain approach for reducing linear, time-invariant systems is presented which produces stable approximations of stable original systems. The method is based upon the schwarz canonical form and pade approximation method. This method does not require the calculation of the alpha-beta(or gamma-delta) table which should be calcuated Routh approximation method. The coefficient of the denominator polynomial are obtained by schwarzs D-table and the coefficient of the numerator polynomial are obtained by moment matching technique.

언센티드 칼만필터를 이용한 순환신경망 학습 및 채널 등화에의 응용

권오신 국립7개대학공동논문집간행위원회 2003 공업기술연구 Vol.3 No.-

Recurrent neural networks have been successfully applied to communications channel equalization. Major disadvantages of gradient-based learning algorithms commonly employed to train recurrent neural networks are slow convergence rates and long training sequences required for satisfactory performance. In a high-speed communications system, fast convergence speed and short training symbols are essential. This paper presents decision feedback equalizers using a recurrent neural network trained with Kalman filtering algorithms. The main features of the proposed recurrent neural equalizer utilizing unscented Kalman filter (UKF), are fast convergence rates and good performance using relatively short training symbols. Experimental result is presented to evaluate the performance of the proposed approaches over a conventional recurrent neural equalizer.