• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.4
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• pp.355-364
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• 2011

In this study, the details of WSA(wavelet series analysis) have been demonstrated to solve the 4th-order elliptic differential equation. It is clear to solve the 2nd-order elliptic differential equation with the basis function of Hat wavelet series that is used in the previous study existed in $H^1$-space. However, it is difficult to solve the 4th order differential equation with same basis function of Hat wavelet series because of insufficient differentiability and integrability. To overcome this problem, the linear equations in terms of moment and deflection have been formulated and solved sequentially that are similar to extension of Elastic Load Method and Moment Area Method in some senses. Also, the differences and common points between the proposed method and the meshless method are discussed in the procedure of WSA formulation. As we expect, it is easy to ascertain that the more terms of Hat wavelet series are used, the better numerical solutions are improved. Also the solutions obtained by WSA have been compared with the conventional FEM solutions in case of Euler beam problems with stress singularity.

• Structural Engineering and Mechanics
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• v.12 no.6
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• pp.657-668
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• 2001

Fiber reinforced cementitious composites are nowadays widely applied in civil engineering. The postcracking performance of this material depends on the interaction between a steel fiber, which is obliquely across a crack, and its surrounding matrix. While the partly debonded steel fiber is subjected to pulling out from the matrix and simultaneously subjected to transverse force, it may be modelled as a Bernoulli-Euler beam partly supported on an elastic foundation with non-linearly varying modulus. The fiber bridging the crack may be cut into two parts to simplify the problem (Leung and Li 1992). To obtain the transverse displacement at the cut end of the fiber (Fig. 1), it is convenient to directly solve the corresponding differential equation. At the first glance, it is a classical beam on foundation problem. However, the differential equation is not analytically solvable due to the non-linear distribution of the foundation stiffness. Moreover, since the second order deformation effect is included, the boundary conditions become complex and hence conventional numerical tools such as the spline or difference methods may not be sufficient. In this study, moment equilibrium is the basis for formulation of the fundamental differential equation for the beam (Timoshenko 1956). For the cantilever part of the beam, direct integration is performed. For the non-linearly supported part, a transformation is carried out to reduce the higher order differential equation into one order simultaneous equations. The Runge-Kutta technique is employed for the solution within the boundary domain. Finally, multi-dimensional optimization approaches are carefully tested and applied to find the boundary values that are of interest. The numerical solution procedure is demonstrated to be stable and convergent.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.8 s.101
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• pp.945-953
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• 2005

The purpose of this paper is to develop a linear regression model for the sound quality index of vehicle Interior noise. For this, objective measurement data of the vehicles driving in acceleration was measured. On the basis of analysis, psychoacoustic parameters were extracted and subjective evaluation was performed by noise and vibration expert evaluators. For the subjective evaluation, the paired comparisons and the semantic differential methods were used to evaluate sound quality of vehicle interior noise. By the paired comparison which evaluate two pairs of vehicle interior noise, the preference was estimated. With the semantic differential and the factor analysis, it was evaluated words of two pairs which expressed appropriately the sense of evaluator about noise source. Therefore the characteristics of the sound qualify for the vehicle were differentiated. From the results of both the correlation analysis and the multiple factor regression analysis, the sound quality evaluation model for the sense of human hearing was derived and indexed.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.10a
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• pp.125-139
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• 2000

The differential enhanced degradation of cis- and trans-1,3-D was observed in the previous two studies performed by Ou et al. (1995) and especially Chung et al. (1999). This study was initiated to investigate the involvement of microorganisms in the differential enhanced degradation of the chemicals. As expected, microorganisms were responsible for the enhanced degradation of the chemicals. A mixed bacterial culture capable of degrading 1,3-D was isolated from an enhanced soil sample collected from a site treated with 1,3-D. Similar to the enhanced soil, the mixed culture degraded trans-1,3-D faster than cis-1,3-D. This mixed culture could not utilize cis- and trans-1,3-D as a sole source of carbon for growth. Rather, a variety of second substrates were evaluated to stimulate the differential enhanced degradation of the two isomers. As a result, the mixed culture degraded cis- and trans-1,3-D only in the presence of a suitable second substrate. Second substrates that had the capacity to stimulate the degradation included soil leachate, tryptone, tryptophan, and alanine. Other substrates tested, including soil extract, glucose, yeast extract, and indole (ailed to stimulate the degradation of the two isomers. Therefore, it appeared that the degradation of cis- and trans-1,3-D was a cometabolic process. The mixed culture was composed of four morphologically distinctive bacterial colonies.

• Journal of the Korea Safety Management & Science
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• v.16 no.4
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• pp.379-389
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• 2014

Fire detectors are designed to minimize loss of life from a fire alarm system as an alarm to help evacuate more quickly until the completion of the evacuation alarm should be continued. the purpose of such alarms in order to achieve the characteristic fire heat release rate reaches a certain level, or when a certain time has elapsed, when the heat detector is to be alarms to answer. Requires a quick response, it is desirable to install the sensor as much as possible, but taking into account the cost of installation problems by engineering approach to minimize the quantity and rapidity of detection capability should be increased. In order to increase the rapidity of fire detectors in a room according to the height of the sensing period is to be maintained the optimum distance of the fire detector detects characteristics should be considered. Differential spot-type heat detectors installed domestic basis, depending on the type of sensor that can detect one sensor area is limited and less than 4m ceiling height regulations and simply double the number in excess of 4m and intended to be installed.

• Journal of the Korean Geographical Society
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• v.47 no.1
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• pp.140-157
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• 2012

Most of global citizens in the globalization era want to live peacefully in the symbiotic relationship among each region or locality with its identity. From this perspective, the new regionalist models of development such as new industrial districts, industrial clusters, regional innovation systems, and global city-regions isn't helpful to most of regions because they were developed to increase the global competitiveness of industrial region from a few advanced industrial areas. This study attempts to develop 'regional differential development' as an alternative regional development theory. This theory puts emphasis on the truth that the difference or differential industry between regions in the real world connotes two essential values of development like the symbiosis of global citizens and the regional identity. Regional differential development seeks the development of regional differential industry on the basis of geographical elements with differential advantage, and hence it reviews significantly geographical elements including location, natural environment(landform, soil, climate, etc.), natural resources, population, transportation, culture, and landscape which appear substantially differently among regions. And to realize regional differential development successfully, it is crucial that actors(government, company, related institutions, and regional residents) actively participate and play each complementary role in the relationship of cooperation and conflict. Further study needs to secure the universal validity of this theory through many empirical studies.

• Journal of the Korea Safety Management & Science
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• v.6 no.1
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• pp.187-199
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• 2004

To suggest a more efficient way of delivering information for process control under computerized environment, population stereotypes of colors were tested with 57 Korean subjects. The subjects were asked to associate 11 colors salient at electronic video displays with 55 pairs of adjectives that might be used when they explain the current state of process. The levels of association were evaluated with semantic differential methods by 7 point scales. Based on the multivariate analyses, the 55 pairs of adjectives were grouped into three distinct dimensions. The emotional maps of the 11 colors with respect to each dimension were presented. The Quantitative relationships between the colors and subjective impressions were also calculated by quantification theory I. On the basis of these color associations, it was suggested a general guideline for color coding when delivering process information

• Archives of Pharmacal Research
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• v.7 no.1
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• pp.47-52
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• 1984

Four polymorphic forms (I, II, III and IV) of hydrochlorothiazide have been characterized on the basis of x-ray diffractometry and differential thermal analysis. Form I was obtained by crystallization from N, N-dimethylformamide and Form II was crystallized from hot methanol. Form III was precipitated from sodium hydroxide aqueous solution by treatment with hydrochloric acid and Form IV was crystallized from 50% methanol. The metastable form I was a most stable form among four polymorphs, which was stable more than ten months at room temperature. The thermodynamic parameters such as heat of solution, enthalpy, entropy, free energy difference and transition temperature were determined by the measurement of intrinsic dissolution rate. The transition temperature and the heat of transition between the metastable Form I an Form II were determined to be $299.15^{\circ}$K and 5.03 Kcal/mole, respectively and free energy difference ($\delta$ F) was 302. 13 cal/mole. Diuretic action of these four polymorphic forms was also evaluated by monitoring the difference in urinary excretion of sodium, potassium and magnesium in rats.

• Structural Engineering and Mechanics
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• v.41 no.2
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• pp.263-284
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• 2012

This paper aims to propose a computational technique for estimating the region of attraction (RoA) for autonomous nonlinear systems. To achieve this, the collocation method is applied to approximate the Lyapunov function by satisfying the modified Zubov's partial differential equation around asymptotically stable equilibrium points. This method is formulated for n-scalar differential equations with two classes of basis functions. In order to show the efficiency of the suggested approach, some numerical examples are solved. Moreover, the estimated regions of attraction are compared with two similar methods. In most cases, the proposed scheme can estimate the region of attraction more efficient than the other techniques.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.183-192
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• 1981

The present study gives an apprximate equation of circular cylindrical shell on the basis of Flugges's exact theory. The longitudinal bending moment .MU.$\_$x/ and circumferential strain .epsilon.$\_$.theta. are assumed to be small to be small and have been neglected. The governing equation of the cylindrical shell, which is generaly presented as 8th order partial differential equation, is reduced into a 4th order partial differential equation for axial coordinate. To verify the validity and accuracy of this approximate theory, the cantilever cylindrical shell subjected to a concentrated load is analyzed. The maximum errors of longitudinal stress and deflection are about 10 percent compared with the analysis by flugge's theory and are about 15 percent with experimental results.