• Advances in Computational Design
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• v.5 no.4
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• pp.397-416
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• 2020

Functionally graded material (FGM) illustrates a novel class of composites that consists of a graded pattern of material composition. FGM is engineered to have a continuously varying spatial composition profile. Current work focused on buckling analysis of beam made of stepwise linear and quadratic graded material in axial direction subjected to axial span-load with piecewise function and rested on shear layer based on classical beam theory. The various boundary and natural conditions including simply supported (S-S), pinned - clamped (P-C), axial hinge - pinned (AH-P), axial hinge - clamped (AH-C), pinned - shear hinge (P-SHH), pinned - shear force released (P-SHR), axial hinge - shear force released (AH-SHR) and axial hinge - shear hinge (AH-SHH) are considered. To the best of the author's knowledge, buckling behavior of this kind of Euler-Bernoulli beams has not been studied yet. The equilibrium differential equation is derived by minimizing total potential energy via variational calculus and solved analytically. The boundary conditions, natural conditions and deformation continuity at concentrated load insertion point are expressed in matrix form and nontrivial solution is employed to calculate first buckling loads and corresponding mode shapes. By increasing truncation order, the relative error reduction and convergence of solution are observed. Fast convergence and good compatibility with various conditions are advantages of the proposed method. A MATLAB code is provided in appendix to employ the numerical procedure based on proposed method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.2
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• pp.170-177
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• 2009

The objective of this study is to evaluate an acoustic emission (AE) source characterization and fracture behavior of the SM45C steel by using back-propagation neural network (BPN). In previous research Ref. [8] about k-nearest neighbor classifier (k-NNC) continuity, we used K-means clustering method as an unsupervised learning method for obtaining multi-variate AE main data sets, such as AE counts, energy, amplitude, risetime, duration and counts to peak. Similarly, we applied k-NNC and BPN as a supervised learning method for obtaining multi-variate AE working data sets. According to the error of convergence for determinant criterion Wilk's ${\lambda}$, heuristic criteria D&B(Rij) and Tou values are discussed. As a result, in k-NNC before fracture signal is detected or when fracture signal is detected, showed that produce some empty classes in BPN. And we confirmed that could save trouble in AE signal processing if suitable error of convergence or acceptable encoding error give to BPN.

• Honam Mathematical Journal
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• v.8 no.1
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• pp.51-74
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• 1986

The thery of measure is significant in that we extend from it to the theory of integration. AS specific metric outer measures we can take Hausdorff outer measure and Lebesgue-Stieltjes outer measure connecting measure with monotone functions.([12]) The purpose of this paper is to find some properties of Lebesgue-Stieltjes measure by extending it from $R^1$ to $R^n(n{\geq}1)$ $({\S}3)$ and differentiation of the integral defined by Borel measure $({\S}4)$. If in detail, as follows. We proved that if $_n{\lambda}_{f}^{\ast}$ is Lebesgue-Stieltjes outer measure defined on a finite monotone increasing function $f:R{\rightarrow}R$ with the right continuity, then $$_n{\lambda}_{f}^{\ast}(I)=\prod_{j=1}^{n}(f(b_j)-f(a_j))$$, where $I={(x_1,...,x_n){\mid}a_j$<$x_j{\leq}b_j,\;j=1,...,n}$. (Theorem 3.6). We've reached the conclusion of an extension of Lebesgue Differentiation Theorem in the course of proving that the class of continuous function on $R^n$ with compact support is dense in $L^p(d{\mu})$ ($1{\leq$}p<$\infty$) (Proposition 2.4). That is, if f is locally $\mu$-integrable on $R^n$, then $\lim_{h\to\0}\left(\frac{1}{{\mu}(Q_x(h))}\right)\int_{Qx(h)}f\;d{\mu}=f(x)\;a.e.(\mu)$.

• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.78-84
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• 2008

As a preliminary step to build a complete superyacht hull design program, the development of superyacht profile design system is introduced. The two-dimensional hull profile is decomposed into four local zones depending upon the functionality and connecting continuity of the profile. Characteristics of each zone are investigated and used to generate the model describing the geometric shape of zone using freeform curves. A set of design parameters is derived from the established geometric model. Generation and modification of a model are is by manipulating the chosen parameters. Four zones designed are integrated to form a final profile. An interactive design system performing all the modeling and modification processes is implemented using the graphic user interface system based an Microsoft Foundation Class and OpenCASCADE, a open graphic library. The shapes of the profiles generated by the developed design system are verified with those of built superyachts. The developed design system will be used for the construction of three-dimensional superyacht hull modeling system.

• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.561-573
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• 2023

National forests have an advantage over private forests in terms of higher investment in capital, technology, and labor, allowing for more intensive management. As such, national forests are expected to serve not only as a strategic reserve of forest resources to address the long-term demand for timber but also to stably perform various essential forest functions demanded by society. However, most forest stands in the current national forests belong to the fourth age class or above, indicating an imminent timber harvesting period amid an imbalanced age class structure. Therefore, if timber harvesting is not conducted based on systematic management planning, it will become difficult to ensure the continuity of the national forests' diverse functions. This study was conducted to determine the optimal volume of timber production in the national forests to improve the age-class structure while sustainably maintaining their economic and public functions. To achieve this, the study first identified areas within the national forests suitable for timber production. Subsequently, a forest management planning model was developed using multi-objective linear programming, taking into account both the national forests' economic role and their public benefits. The findings suggest that approximately 488,000 hectares within the national forests are suitable for timber production. By focusing on management of these areas, it is possible to not only improve the age-class distribution but also to sustainably uphold the forests' public benefits. Furthermore, the potential volume of timber production from the national forests for the next 100 years would be around 2 million m³ per year, constituting about 44% of the annual domestic timber supply.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.2
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• pp.541-550
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• 2016

Considering the results of the 3.20 Cyber Attack, leaks of personal information by card companies, and so on, convenience and efficiency cannot be guaranteed without security as a prerequisite. In addition, it is more likely that customers' interests seem to be interfered with in financial institutions than in any other industry. Therefore, when a security accident occurs, users may suffer mental damage and monetary loss, leading to class action, customer defection, loss of reputation, and falloff in international credibility, which all may have a significant effect on the business continuity of corporations. This study integrates the representative information security certification systems in order to improve the efficiency of information security management and demonstrate the necessity of information security management system certification for the financial sector. If the certification is needed, we would like to recommend the desirable development direction.

• Structural Engineering and Mechanics
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• v.68 no.4
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• pp.385-398
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• 2018

In the present paper, we offer a new flat shell finite element. It is the result of the combination of a membrane element and a bending element, both based on the strain-based formulation. It is known that $C^{\circ}$ plane membrane elements provide poor deflection and stress for problems where bending is dominant. In addition, they encounter continuity and compliance problems when they connect to C1 class plate elements. The reach of the present work is to surmount these problems when a membrane element is coupled with a thin plate element in order to construct a shell element. The membrane element used is a triangular element with four nodes, three nodes at the vertices of the triangle and the fourth one at its barycenter. Each node has three degrees of freedom, two translations and one rotation around the normal. The coefficients related to the degrees of freedom at the internal node are subsequently removed from the element stiffness matrix by using the static condensation technique. The interpolation functions of strain, displacements and stresses fields are developed from equilibrium conditions. The plate element used for the construction of the present shell element is a triangular four-node thin plate element based on Kirchhoff plate theory, the strain approach, the four fictitious node, the static condensation and the analytic integration. The shell element result of this combination is robust, competitive and efficient.

• Hwankyungkyoyuk
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• v.18 no.2 s.27
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• pp.23-30
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• 2005

The purpose of this study is to develop School Agenda 21 to activate environmental education at schools. In detail, this study is intended to develop operating procedures, major issue areas or domains, and instructions on the preparation for School Agenda 21. School Agenda 21 means the action plan which students, teachers, parents, and other concerned parties (including office of education, local municipal bodies, and NGOs) write under agreement with respect to their respective roles in order to activate environmental educations oriented toward sustainable development. The results of this study are as follow. First, the operating procedures for School Agenda 21 consist of seven steps; organization, diagnosis of problems, setup of targets or objectives, development of codes of behavior, system establishment, practices and reviews, and evaluation and feedbacks. Second, major issue areas for School Agenda 21 are classified into six; school management, class operation, independent subject activity, separate subject activity, non-subject activity, and external relations of school. Third, instructions of the preparation of School Agenda 21 address these 10 concepts; balance, unification, continuity, daily routine, linkage, environmental justice, participation, peculiarity of schools and classes, regional peculiarity, and concreteness, which consider 7 principles for environmental education, levels of learners, regional features, and concreteness. School Agenda 21 developed from this study converts existing environmental education toward sustainable development environmental education, and developed for the purpose to activate school environmental education, but ultimate purpose of this study are realizing sustainable society, sustainable future to realize education for sustainable development. So School Agenda 21 is expected to important performance way making possible Local Agenda 21, National Agenda 21, Agenda 21 as if education, public recognition and discipline contents of the 36 chapter of Agenda 21.

• Journal of the Korean housing association
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• v.21 no.1
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• pp.53-65
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• 2010

Apartment buildings represent the most typical patterns of housing in Korea. The present plans are very different from the previous ones when they appeared for the first time. Although apartment unit plans has changed drastically, they can be classified into several categories. Apartment unit plans reflects the demands of living activities and space dimensions of unit plans have the characteristics of diachronic continuity and carry the values of living culture. Thus this study aims to provide the statistical dimensional data of each room that can be actually used for the design of unit plans by sub-grouping typical unit plans. The statistical data of this study showed that apartment unit plans are shifting from 2bay/3room type to 3bay/3room type in 1990s. It is very peculiar that the typical unit plan of $60\;m^2$ area becomes to resemble that of $85\;m^2$ area. The space arrangement of typical unit plans of both $60\;m^2$ and $85\;m^2$ area is almost identical while only their space dimensions differ slightly. As the mean/mode/median values of space dimensions in a typical unit plan are converging into a range of narrow margin, space dimensions of typical unit plan are contended to be strictly regular. The statistical numeric data of various space dimensions provided in this paper can be applied practically to the design of apartment unit plans for low income class people who are disprivileged in the society.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.213-219
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• 1992

Geomorphological properties for the phylite-derived soil were examined to relate processes to four landscape positions, shoulder, backslope, footslope, and toeslope in Chungbuk. The distribution of Ogcheon-geology system was 216 thousand ha in South Korea. 2 orders, 3 suborders, 4 great groups, 5 subgroups, and 9 series were mapped. Soil color was interlocked by landscape. Soil color index values and $Fe_2O_3$ contents increased with soil-drainge class. Silt/clay and Ca/Mg ratios tended to narrow wish elevation and decreased with depth. Therefore, profile development or age on the landscape position was shoulder>backslope>footslope>toeslope. Color index(C2m) has a sighificant correlation with $Fe_2O_3$, in soil profile($r=0.777^{**}$). Pedologic type was continuity/discontinuity and soil property changes of depth<12cm would have a continous function.