• Bulletin of the Korean Mathematical Society
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• v.20 no.2
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• pp.111-122
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• 1983

지금까지 H. Aebli, A. Fricke, R.W. Copeland, G. Steiner, E. Wittmann, R.R.Skemp, Z.P. Dienes등에 의해 Piaget이론의 수학교육적 연구가 상당한 정도로 이루어져 왔다. 그러나 Centre International D'epistemologie Genetique를 중심으로 한 집단사고와 방대한 연구결과를 집약한 소위 'Piaget이론'은 타에 그 종례를 찾아볼 수 없는 포괄적인 것인 바, 지금까지 이루어진 Piaget이론의 수학교육적 접근은 Piaget이론의 한정된 부분의 단편적인 응용에 불과하며, Piaget의 발생적 수학인식론 및 심리학의 중심원리와 연구결과를 반영한 보다 철저한 연구가 요망되고 있다. 본 고는 그 이론적 기초에 관한 연구의 일환으로 1969년에 출판된 Psychologie et pedagogie에 실린 'La didactique des mathematiques'와 1972년 ICMI의 제2차 수학교육국제회의에 기고한 논문 'Comments on mathematical education'에 나타난 수학교육에 대한 Piaget자신의 견해를 그의 수학인식론의 분석적 고찰을 통해 양세화하고, 그 실제적 구현방안을 제시해 본 것이다.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.192-197
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• 2001

To obtain $A_2$ experimentally in the $J-A_2$ theory, deformation field on the lateral surface of a CT specimen was to be determined using Laser speckle method. The crack growth was measured using direct current potential drop method and most procedure of experimental and data reduction was performed according to ASTM Standard E1737-96. Laser speckle images during crack propagation were monitored by two CCD cameras to cancel the effect of rotation and translation of the specimen. An algorithm to pursue displacement of a point from each image was developed and successfully used to measure $A_2$ continuously as the crack tip was propagated. The effects of specimen thickness on J-R curve and $A_2$ were explored.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.428-429
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• 1999

잘 알려져 있듯 광화학 오존 생성의 첫 단계는 N $O_2$가 자외선을 받아 NO와 O로 해리되는 과정이다. N $O_2$ ＋ h$\upsilon$ $\longrightarrow$ NO ＋ O 일반적으로 이러한 광해리 반응을 정량화하기 위하여 아래의 식과 같이 광해리 상수, $J_{NO2}$를 정의한다.(중략)략)

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.294-298
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• 2000

The output characteristics of intracavity frequency doubling of laser-diode end-pumped Nd:S-VAP laser were investigated. Nd:S-VAP is suitable for a microchip laser medium, which has a low threshold property because of a very high value of the stimulated emission cross-section and lifetime product. The threshold energy measured was 81 J.ll. The second harmonic output energy measured was $126\mu\textrm{J}$at a pump energy of $2\mu\textrm{J}$. We described for intracavity frequency doubling by using theoretical calculations. Q-switched second harmonic energy measured was $15\mu\textrm{J}$per pulse with a pulse-width of 26 ns. at a pump energy of 2 mJ and an $M^2$ of 1.47 represented a good beam quality. ality.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.153-163
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• 2000

The size effect on fracture toughness was investigated by introducing $J-A_2$ theory. For this application,small size specimens were chosen to establish $J-A_2$ assessment curve with FEM analysis. Two-dimensional FEM analysis was conducted with plane strain model using ABAQUS by domain integral method to calculate both crack tip stress and fracture toughness which were used to establish $J-A_2$ curve. The assessment curve predicted the fracture toughness of large specimens very well when compared to the test values. The results showed good prediction for deep crack specimen, though there were acceptable deviations in shallow cracked specimens, presumably caused by constraint effect. When the curve applied to reactor vessel in order to predict end of life fracture toughness with assumption of on-power pressure test condition, it provided the reasonable pressure compared to the existing design value. Better predictions would be possible if more test data were available.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.1
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• pp.119-125
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• 2003

A way to measure the second parameter $A_2$of CT specimens is described. The displacement $\delta$$_{5}$ which is measured continuously from visual images of the lateral surface during crack growth is used to calculate the A, as a function of crack growth. The crack length is measured by DCPD(Direct Current Potential Drop) method and the J-resistance curve is determined according to ASTM standard E1737-96. To prove the validity of this method, three dimensional finite element analyses were performed, and variations of the displacements $\delta$$_{5}$ and $A_2$along the thickness were explored. As the result, it has been shown that the $\delta$$_{5}$ measured from the visual images of the lateral surface and the corresponding $A_2$can be regarded as the average through the thickness for 1T and 1/2T specimens of SA106Gr.C steel.steel.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.15-24
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• 2015

Jacket matrices which are defined to be $m{\times}m$ matrices $J^{\dagger}=[J_{ik}^{-1}]^T$ over a Galois field F with the property $JJ^{\dagger}=mI_m$, $J^{\dagger}$ is the transpose matrix of element-wise inverse of J, i.e., $J^{\dagger}=[J_{ik}^{-1}]^T$, were introduced by Lee in 1984 and are used for Digital Signal Processing and Coding theory. This paper presents some square matrices $A_2$ which can be eigenvalue decomposed by Jacket matrices. Specially, $A_2$ and its extension $A_3$ can be used for modifying the properties of hyperbola and hyperboloid, respectively. Specially, when the hyperbola has n times transformation, the final matrices $A_2^n$ can be easily calculated by employing the EVD[7] of matrices $A_2$. The ideas that we will develop here have applications in computer graphics and used in many important numerical algorithms.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.9
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• pp.514-519
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• 2002

We are considering the following problem that can be used in the prediction of the structure of proteins. Given two length n arrays A, B with positive numbers and a positive number M, find all pairs of subarrays A[i]＋…A[j],$1{\leq}i{\leq}j{\leq}n$ such that A[i]＋…A[j]＋B[k]＋…B[l]=M. This paper presents an algorithm with $Ο(n^2log n+K)$ time using Ο(n) memory, where K is the number of pairs output. The previously best known one is with $Ο(n^2log +Klog n)$ time and Ο(n) memory.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.4
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• pp.589-594
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• 2002

The filter of hairpin type can be designed small but has a demerit which a design method is complex. This paper suggests the method that a hairpin line filter is designed with applying a transmission line method and J inverter circuit, accurately calculated the J value and the b parameter. It is considered about the line have no the mutual coupling element with next line to each other. is calculated a length of electric coupling line about coupling element in each inverter stage from the J value and the b parameter. In order to show the validity of the proposed design method, band pass filter of small hairpin line is designed at center frequency 2.6 GHz, with Serenade 8.0 software tool and the simulation characteristics are compared with design results.

• Journal of ILASS-Korea
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• v.3 no.2
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• pp.1-13
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• 1998

A theoretical and experimental study was carried out to predict the drop size distribution of the pressure swirl atomizer. Various analytical methods using the Kelvin-Helmholtz instability theory were tried to examine the wave growth on cylindrical liquid sheets. Cylinderical liquid sheets were extended to the case with the conical sheets. Perturbations due to tangential motion as well as longitudinal one were taken into account. And it was assumed that the breakup occurs when amplitude ratio exceeds exp(12), drop sizes were predicted only by theoretical approach. Drop size distribution was obtained by using maximum entropy formalism. Seven constraints in the form of the definition of mean diameter were used in this formulation in order to avoid the difficulties of estimating source terms. In this study $D_{10}$ only was introduced into the formulation as a constraint. The predicted drop size and drop size distribution agreed well with the measured data.