• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.208-215
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• 1998

A stability problems of isotropic shells under pure bending is investigated based on the classical shells theory. The governing equations of stability problem presented by Donnell and Love, are developed and the solutions for the cylindrical shells are obtained by using Galerkin method. Bending moment is applied at the ends of the cylindrical shell as a from of distributed load in the shape of sine curve. For the isotropic materials, the result of the general purpose structural analysis program based on the finite element method are compared with the critical moment obtained from the classical shell theories. The critical loads for the cylindrical shells with various geometry can not be evaluated with a simple equation. However, accurate solutions for the stability problems of cylindrical shells can be obtained through the equilibrium equation developed in the study.

• 대한기계학회논문집A
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• 제28권2호
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• pp.133-142
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• 2004

In this article, the constitutive relations of three types of piezoelectric benders, which are a unimorph bender, a bimorph bender and a triple-layer bender, are derived based on the beam theory under the quasi-static equilibrium condition. The relation coefficients are described as the geometry and material properties of the benders. More general constitutive relations involving fixed-free, fixed-roll, and fixed-simply supported boundary conditions under the inconsistent length condition between the piezoelectric layer and the nonpiezoelectric one are discussed. The complicated constitutive relations can be easily calculated and checked by using the symbolic function in ‘Mathematica’. The relation coefficients for the benders are plotted in three dimensional graph using the developed program.

• Bulletin of the Korean Chemical Society
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• 제1권3호
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• pp.109-112
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• 1980

Ultraviolet spectrophotometric investigations were carried out on monoalkylbenzene-iodine systems in carbon tetrachloride. The results reveal the formation of one-to-one molecular complexes. On the basis of the equilibrium constants for these complexes of representative monosubstituted benzenes, the following order of increasing stability is obtained: i-propyl- ${\Delta}$H, ${\Delta}$G and ${\Delta}$S for the interaction of a number of monoalkyl substituted benzenes with iodine have been determined. In general, it can be said that as ${\Delta}$H becomes increasingly negative, corresponding decreases in the ${\Delta}$G and the ${\Delta}$S values are observed, and these variations are linear. The thermodynamic constants become increasingly negative with increasing monoalkyl substitution of the aromatic donor nucleus. The complex bond is therefore weak, and its formation is accompanied by relatively small entropy changes. Thus, analysis of these findings is discussed.

• Bulletin of the Korean Chemical Society
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• 제17권2호
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• pp.131-138
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• 1996

The conformational transition of oligopeptide multimer,-(HPPHPPP)n-, is studied (H:hydrophobic amino acid, P:hydrophilic amino acid). The helix/coil transitions are detected in the multimer. The transition depends on the number of amino acid in the sequence, the concentration of the oligopeptide, and temperature which affects helix stability constant (${\xi}$) and hydrophobic interaction parameter (wj). In the thermodynamic equilibrium system jA${\rightarrow}$Aj (where A stands for oligopeptide monomer), Skolnick et al., explained helix/coil transition of dimer by the matrix method using Zimm-Bragg parameters ${\xi}$ and $\sigma$ (helix initiation constant). But the matrix method do not fully explain dangling H-bond effects which are important in oligopeptide systems. In this study we propose a general theory of conformational transitions of oligopeptides in which dimer, trimer, or higher multimer coexists. The partition of trimer is derived by using zipper model which account for dangling H-bond effects. The transitions of multimers which have cross-linked S-S bonds or long chains do not occur, because they keep always helical structures. The transitions due to the concentration of the oligopeptides are steeper than those due to the chain length or temperature.

• Structural Engineering and Mechanics
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• 제78권5호
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• pp.573-583
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• 2021

This paper presents a theoretical approach of the structures reinforced with bonded FRP composites, taking into account loading model, shear lag effect and the thermal effect. These composites are used, in particular, for rehabilitation of structures by stopping the propagation of the cracks. They improve rigidity and resistance, and prolong their lifespan. In this paper, an original model is presented to predict and to determine the stresses concentration at the FRP end, with the new theory analysis approach. The model is based on equilibrium and deformations compatibility requirements in and all parts of the strengthened beam, i.e., the concrete beam, the FRP plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. The numerical resolution was finalized by taking into account the physical and geometric properties of materials that may play an important role in reducing the stress values. This solution is general in nature and may be applicable to all kinds of materials.

• Structural Engineering and Mechanics
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• 제68권1호
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• pp.53-66
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• 2018

This paper presents an analysis of the bending, buckling and free vibration of functionally graded sandwich beams resting on elastic foundation by using a refined quasi-3D theory in which both shear deformation and thickness stretching effects are included. The displacement field contains only three unknowns, which is less than the number of parameters of many other shear deformation theories. In order to homogenize the micromechanical properties of the FGM sandwich beam, the material properties are derived on the basis of several micromechanical models such as Tamura, Voigt, Reuss and many others. The principle of virtual works is used to obtain the equilibrium equations. The elastic foundation is modeled using the Pasternak mathematical model. The governing equations are obtained through the Hamilton's principle and then are solved via Navier solution for the simply supported beam. The accuracy of the proposed theory can be noticed by comparing it with other 3D solution available in the literature. A detailed parametric study is presented to show the influence of the micromechanical models on the general behavior of FG sandwich beams on elastic foundation.

• 대한교통학회지
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• 제32권4호
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• pp.357-368
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• 2014

지금까지 토지이용-교통모형은 전적으로 수치해석적 분석도구로만 이용되어 왔는데, 최근 이론개발 노력의 결과 정책변수에 대한 후생함수의 1계 도함수 간편식을 구할 수 있게 되었다. 본 논문은 혼잡통행료가 소득세 경감을 통해 재순환될 때 혼잡통행료의 변화에 대한 후생함수의 도함수를 어떻게 유도할 수 있는지 보여준다. 분석결과 혼잡통행료의 부과가 가져오는 후생변화분을 (1)혼잡의 완화로 인한 후생증가분과 (2)노동공급과의 상호작용에서 발생하는 후생손실로 분해할 수 있다. 이 결과는 기존의 연구결과와 일치한다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권5호
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• pp.362-368
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• 2004

A new one-column chromatography process, analogous to a four-zone simulated moving bed (SMB), was presented. The basic principle of the process was identical to that of a four-zone SMB. The process consisted of one chromatographic column and four tanks, instead of the four columns in the four-zone SMB (1-1-1-1), and has been used for the separation of two amino acids, phenylalanine and tryptophan, using an ion exchange resin. The operating parameters for the one-column process and four-zone SMB were obtained from equilibrium theory. Computer simulations were used to compare the performances of the new one column process to that of the general four-zone SMB, using Aspen $Chromatography^{TM}$ v 11.1. The differences between the one-column and SMB processes in terms of the purities and yields of phenylalanine and tryptophan were less than 4 and about $6\%$, respectively. The lower purities of the one-column process were due to the loss of the developed concentration profiles in the column when the liquid was stored in tanks. The one-column process gave great flexibility, and would be useful for reconstructing an existing conventional chromatography process to one of a SMB.

• 한국시스템다이내믹스연구
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• 제14권4호
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• pp.63-89
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• 2013

The purpose of this paper is to explain the entropic measures could cause the organization to increase the entropy. The organization as an open system has a tendency to input new energy to adapt itself to the change in its surroundings. This intention of inputting energy into organization is based on the second law of thermodynamics, the laws of entropy.Entropy is a measure of disorder, or a measure of progressing towards thermodynamic equilibrium. The entropy of an isolated system increases. Organizations have to open to their environment, have to do something to reduce their entropy. But, this attempt to reduce entropy entails another entropy. This study shows the side effects by giving examples of illegal receipt of worker's compensation insurance. The implications through the cases of illegal receipt of workers' compensation are as follows. Firstly, organizational policy is that inaction in itself may be the best policy, unless we always think the action best. Secondly, public organization should be careful in substituting business management in the private sector such as customer satisfaction(CS) for the value in public sector. Thirdly, the setting the expiration date of organizational policy could be the way to slow down the degree of entropy.

• The Journal of Asian Finance, Economics and Business
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• 제7권11호
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• pp.13-22
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• 2020

This research explores the appropriate rubber pricing model and the consistent empirical evidence. This model has been derived from the utility function and firm profit-maximization model of commodity goods. The finding shows that the period t - 1 affects expected commodity price and expected profit of commodity production. In fact, a change in the world price of rubber in the past period led to a change in the expected price of rubber in the short run which influenced the expected rubber profit. As a result, the past-period free on board price has an entirety effect on expected farm price of rubber given an exchange rate. In addition, the rubber pricing model indicates that the profit of local farmer on rubber plant depends solely on the world price of rubber in the short run in case of Thailand. In an empirical study, it was found that a change in the price of ribbed smoke sheet 3 in Singapore Commodity Exchange significantly and positively determined the fluctuation of rubber price at the farm gate in Thailand which was consistent with the behavior of the Thai farmers. Both prices are also cointegrated in the long run. That is, the result states that the VECM is an appropriated pricing model for forecasting the farm price in Thailand.