• Bulletin of the Korean Mathematical Society
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• v.52 no.2
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• pp.377-394
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• 2015

In this paper, we generalize some results about Bertrand curves and Razzaboni surfaces in Euclidean 3-space to the case that the ambient space is Minkowski 3-space. Our discussion is divided into three different cases, i.e., the parent Bertrand curve being timelike, spacelike with timelike principal normal, and spacelike with spacelike principal normal. For each case, first we show that Razzaboni surfaces and their mates are related by a reciprocal transformation; then we give B$\ddot{a}$cklund transformations for Bertrand curves and for Razzaboni surfaces; finally we prove that the reciprocal and B$\ddot{a}$cklund transformations on Razzaboni surfaces commute.

• Applied Microscopy
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• v.34 no.4
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• pp.211-221
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• 2004

In this review, the kinematical scattering theorems are explained by means of Fourier transformation of the assemblies of atoms. The reciprocal space and the generalized Patterson function are introduced. The scatterings of real monatomic gas or liqiud and the hydrogen atoms are described as examples.

• Journal of The Korean Association For Science Education
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• v.12 no.2
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• pp.31-42
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• 1992

The purposes of this study were to find out the degree of formation of the concept of density for the junior high students. The changing pattern of concept in acquiring the concept of density and the degree of development of INRC transformation ability related to the concept of density were also analyzed according to cognitive level and teaching method. The results of this study were as follows. 1) The experimental group were more effective than control group in the formation of the concept of density. 2) Even though students had been taught the concept of density, the various types of preconception were remained and persisted. Especially, the students at concrete level had persisted misconceptions and these misconceptions had been changed to the other misconceptions. 3) In the degree of the formation of the transformation ability of INRC group related to the concept of density in solid phase, the experimental group developed much better on both the abilities of Reciprocal transformation, Correlative transformation and the abilities to manipulate two variables such as volume and mass than control group. 4) The correlation coefficient between GALT score and achivement of the concept of density was 0.67. The correlation coefficient between achivement of the concept of density and the formation the transformation of INRC group related to the concept of density was 0.78.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.195-197
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• 1987

A new method of model reduction, based on the differentiation of polynomials, is Introduced by Gutman(1982). Without the reciprocal transformation, and the differentiation of the numerator and denominator polynomials of the transfer function, used by Gutman, the lower-order system can be obtained by the permutation of the order of numerator and denominator and the number of differentiation.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.3
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• pp.39-46
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• 1991

The effects of austenitizing temperatures and times and cooling rate on the characteristics of continuous air cooling have been investigated for 0.3%C-Mn steels microalloyed with vanadium. Transformation start temperatures have been found to be measured from temperature-time curve directly obtained with continuous air cooling and to decrease with increasing austenitizing temperature, cooling rate and Mn contents. The coarsening behavior of austenite grain size has been measured to abnormally grow at $1050^{\circ}C$ and rapidly grow at $1200^{\circ}C$. It has been found that the volume fraction of pearlite was linealy proportional to the reciprocal square root of austenite grain size. The hardness has been measured to increase with increasing cooling rate up to $250^{\circ}C/min.$ and to remain relatively unchanged in the range of $250{\sim}400^{\circ}C/min.$ showing that hardness valves for steel with a higher Mn content increase more than those for steel with a lower Mn content. The impact property has been found to decrease with increasing of austenite grain size but does not linealy change with the reciprocal square root of austenite grain size.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1462-1470
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• 2003

According to the necessity about information security as well as the advance of IT system and the spread of the Internet, a variety of cryptography algorithms are being developed and put to practical use. In addition the technique about cryptography attack also is advanced, and the algorithms which are strong against its attack are being studied. If the linear transformation matrix in the block cipher algorithm such as Substitution Permutation Networks(SPN) produces the Maximum Distance Separable(MDS) code, it has strong characteristics against the differential attack and linear attack. In this paper, we propose a new algorithm which cm estimate that the linear transformation matrix produces the MDS code. The elements of input code of linear transformation matrix over GF$({2_n})$ can be interpreted as variables. One of variables is transformed as an algebraic formula with the other variables, with applying the formula to the matrix the variables are eliminated one by one. If the number of variables is 1 and the all of coefficient of variable is non zero, then the linear transformation matrix produces the MDS code. The proposed algorithm reduces the calculation time greatly by diminishing the number of multiply and reciprocal operation compared with the conventional algorithm which is designed to know whether the every square submatrix is nonsingular.

• Journal of the Korea Fashion and Costume Design Association
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• v.9 no.2
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• pp.167-178
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• 2007

The purpose of this study is to systematically examine fusion phenomenon in the cultural aspect aiming to grasp the characteristics of fusion phenomenon, which has a steady impact on fashion trend. A reason for fusion to be noted as a cultural code is because diversely cultural interpretations are impossible from one viewpoint. Therefore, it is aimed to inquire into the characteristics of fusion culture, which is one phenomenon of newly mass culture, and to examine which cultural fusion phenomenon in modern fashion is being displayed in fashion design. First, the culturally fusion phenomenon, which was indicated in modern fashion, is displayed as repetition. The fusion, which integrates into fashion as a cultural code, is a trend of pursuing the experience with different culture. The needs of consumers are shown as fusion fashion that repeatedly uses the traditional detail and the modern detail through cultural repetition. Second, it is displayed as transformation. A concept of fusion is not the simple aggregate in [1+1=2], but the creation of new culture called [1+1=1]. In modern fashion, the cultures in the East and the West are harmoniously transformed, and through transformation, each culture is being compressively delivered. Third, it is displayed as interdependency. The fusion fashion which was newly re-interpreted while having reciprocal influence upon mutual culture, is re-interpreted by forming the equal relationship in heterogeneous elements without destroying fashion that was made previously.

• Journal of the Korean Society for Heat Treatment
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• v.10 no.2
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• pp.93-100
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• 1997

Effect of austenite grain size on starting temperature of ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation($M_s$) has been studied in an Fe-18%Mn alloy. Particular attention was paid on the variation of stacking fault energy with austenite grain size, which is considered to be a important factor affecting ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation. Austenite grain size was increased in a wide range from $13{\mu}m$ to $185{\mu}m$ with increasing solution treatment temperature from $700^{\circ}C$ to $1100^{\circ}C$. Hardness was decreased with increasing austenite grain size while the volume fraction of ${\varepsilon}$ martensite showed a reverse tendency, which indicates that the hardness is more dependent on austenite grain size than ${\varepsilon}$ martensite content. No significant change was found in $M_s$ temperature when the grain size was larger than about $30{\mu}m$. In case that, the austenite grain size was smaller than about $30{\mu}m$, however, $M_s$ temperature was marlkedly decreased with decreasing austenite grain size. A linear relationship between $M_s$ temperature and the stacking fault formation probability, i.e. the reciprocal of the stacking fault energy was obtained, which suggests that the variation of $M_s$ temperature with austenite grain size is closely related to the change in stacking fault energy.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.6
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• pp.948-955
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• 1987

The model reduction method of the high order linear time invariant systems is proposed. The continuous fraction expansion of Auxiliary denominator polynomial is used to obtain denominator polynomial of the reduced order model, and the numerator polynomial of the reduced order model is obtained by equating the first some moments of the original and the reduced order model, using simplified moment function. This methiod does not require the calculation of the reciprocal transformation which should be calculated in Routh approximation, furthemore the stability of the reduced order model is guaranted if original system is stable. Responses of this method showed us good characteristics.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.4
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• pp.583-589
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• 1987

A new approximation method is proposed for the linear model reduction of high order dynamic systems. This mehtod is based upon the denominator table(D-table) and time moment-matching technique. The denominator table(D-table) is used to obtain the denominator polynomial of reduced-order model, and the numerator polynomial is obtained by time moment-matching method. This proposed method does not require the calculation of the alpha-beta expansion and reciprocal transformation which should be calculadted by Routh approximation method. The advantages of the proposed method are that it is computationally every attractive better than Routh approximation method and the reduced model is stable Il the original system is stable.