• Journal of applied mathematics & informatics
• /
• v.6 no.2
• /
• pp.393-406
• /
• 1999

Affine invariant sufficient conditions are given for two local convergence theorems involving inexact Newton-like methods. The first uses conditions on the first Frechet-derivative whereas the second theorem employs hypotheses on the second. Radius of con-vergence as well as rate of convergence results are derived. Results involving superlinear convergence and known to be true for inexact Newton methods are extended here. Moreover we show that under hypotheses on the second Frechet-derivation our radius of convergence results are derived. Results involving superlinear convergence and known to be true or inexact Newton methods are extended here. Moreover we show that under hypotheses on the second Frechet-derivative our radius of conver-gence is larger than the corresponding one in [10]. This allows a wider choice for the initial guess. A numerical example is also pro-vided to show that our radius of convergence is larger then the one in [10].

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.808-813
• /
• 2007

We present the numerical characteristics of a new true stress-strain curve acquisition method over a large range of strains by the tensile test and a finite element method through comparing the results obtained by various finite element mesh systems. The method is introduced in detail. The effects of the finite element mesh systems on the results are investigated to show its numerical characteristics of the new method. It is shown that the method is quite robust, implying that it can be used as a special function of the tensile test machines.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.3-7
• /
• 1995

Force generated during grinding process causes elastic defomation. The effect of this deforms a workpiecs. So grinding system is explainable using the concept of macining elasticity phenomenon. Machining elasticity is defined as ratio between the true depth of c ut, and an importnat factor to affect material removal mchanism and productivity. Generally, to produce accurate surface and dimensionally precise components operators depend on their experiences. Because of these, productivity is reduced and time is wasted. The objective of this reserch is to study the effect of grinding conditions, such as table speed, depth of cut on the machining elasticity parameter.

• Journal of Chest Surgery
• /
• v.29 no.1
• /
• pp.52-58
• /
• 1996

Sixty six patients who were operated as lung cancer during the period from Mar. 1991 to Sep. 1993 at the department of Thoracic and cardiovascular surgery, were reviewed retrospectively and the accuracy of regional lymph node in preoperative CT were compared with histopathologlc report obtained from operation. The age ranged from 30 to 72 years old (mean age : 56.5), and 51 patients were male and 15 patients were female. The author analysed the true positive, true negative, false positive and false negative and sensitivity, specificity, positive predictive index, negative predictive index and accuracy of each nodes. The result is that there were differences between seven nodal groups in specificity, sensitivity, positive predictive Index, negative predictive index and accuracy. The range of each nodal group is from 81.7 to 98.3% The nodes of the most poor accuracy are aortopulmonary area and hilar area.

• Journal of the Korean Society of Industry Convergence
• /
• v.20 no.1
• /
• pp.81-87
• /
• 2017

In order to reduce the weight of the blow motor case and to maintain the strength of the motor joint, the mechanical joining strength is to be predicted. The true stress - true strain curves for finite element analysis were obtained through tensile tests of HGI and DP 780 steel. The mechanical joining strength was predicted through an explicit finite element analysis and the accuracy of the predicted results was verified by actual sample test. The regression equation for predicting the mechanical joining strength to the thickness of the DP 780 steel was derived. The minimum thickness of DP 780(1.2mm), which is equivalent to the joining strength of HGI(2.6mm), was derived from the equation.

• Proceedings of the Korean Information Science Society Conference
• /
• 2008.06b
• /
• pp.275-280
• /
• 2008

본 논문에서는 한글 글립(glyph)의 형태학적 분석을 통해 자동으로 획을 분할하는 방법을 제안한다. 제안된 방법은 thinning된 한글 글립의 골격(skeleton) 이미지를 기반으로, 획 분리, 획 병합, 그리고 획 볼륨 복원의 세가지 단계를 거쳐 한글의 기본 획들을 추출해 낸다. 실험 결과, 트루타입폰트(TrueType Font)에 대해서는 80%, 손글씨(Handwriting) 글립에 대해서는 72%의 획 분할 정확도를 보였다. 본 논문에서 제안한 방법으로 획득된 획 정보를 이용하여, 향후 한글 손글씨 생성을 위한 연구를 하고자 한다.

• Bulletin of the Korean Mathematical Society
• /
• v.53 no.4
• /
• pp.1087-1094
• /
• 2016

On a compact n-dimensional manifold M, it has been conjectured that a critical point of the total scalar curvature, restricted to the space of metrics with constant scalar curvature of unit volume, is Einstein. In this paper, after derivng an interesting curvature identity, we show that the conjecture is true in dimension three and four when g is weakly Einstein. In higher dimensional case $n{\geq}5$, we also show that the conjecture is true under an additional Ricci curvature bound. Moreover, we prove that the manifold is isometric to a standard n-sphere when it is n-dimensional weakly Einstein and the kernel of the linearized scalar curvature operator is nontrivial.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.3C
• /
• pp.241-247
• /
• 2002

In this paper, we proposed a continuously variable true time-delay for transmit linear phased-array antenna sing chirped fiber gratings(CFGs) and a tunable laser source. Average group delay-slope of the CFG was treasured to be 177 ps/nm at L-, S-, and X-band. Simulation results show that the maximum gain of the transmit linear phased-array antenna with the beam steering angle of 180$^{\circ}$ is 11.6 dB at 10 GHz.

• The Korean Journal of Applied Statistics
• /
• v.25 no.3
• /
• pp.471-483
• /
• 2012

One of the most important problems in cluster analysis is the selection of variables that truly define cluster structure, while eliminating noisy variables that mask such structure. Brusco and Cradit (2001) present VS-KM(variable-selection heuristic for K-means clustering) procedure for selecting true variables for K-means clustering based on adjusted Rand index. This procedure starts with the fixed number of clusters in K-means and adds variables sequentially based on an adjusted Rand index. This paper presents an updated procedure combining the VS-KM with the automated K-means procedure provided by Kim (2009). This automated variable selection procedure for K-means clustering calculates the cluster number and initial cluster center whenever new variable is added and adds a variable based on adjusted Rand index. Simulation result indicates that the proposed procedure is very effective at selecting true variables and at eliminating noisy variables. Implemented program using R can be obtained on the website "http://faculty.knou.ac.kr/sskim/nvarkm.r and vnvarkm.r".

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.28A no.11
• /
• pp.874-879
• /
• 1991

The effect of air gap between specimen and jig on the material constant (permittivity, permeability) and attenuation characteristics of electromagnetic wave absorbers in the coaxial line method was investigated. The presence of a air gap made both permittivity and permeability measured lower than true value, and the tendency was greater in the case of permittivity. An inner gap compared to an outer gop was found to yield a larger difference between measured and true values. The effect of air gap was measured for a Ni0.3Zn0.7Fe2O4, with the gap eliminated by metallizing with Ag-paste. The measured characteristics were in good agreement with corrected values by calculation.