• Coupled systems mechanics
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• v.11 no.2
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• pp.151-166
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• 2022

Peltier cells have low efficiency, but they are becoming attractive alternatives for affordable and environmentally clean cooling. In this line, the current article develops closed-form and semianalytical solutions to improve the temperature distribution of Bi₂Te₃ thermoelements. From the distribution, the main objective of the current work-the optimal electric intensity to maximize cooling-is inferred. The general one-dimensional differential coupled equation is integrated for linear and quadratic geometry of thermoelements, under temperature constant properties. For a general shape, a piece-wise solution based on heat flux continuity among virtual layers gives accurate analytical solutions. For variable properties, another piece-wise solution is developed but solved iteratively. Taking advantage of the formulae, the optimal intensity is directly derived with a minimal computational cost; its value will be of utility for more advanced designs. Finally, a parametric study including straight, two linear, barrel, hourglass and vase geometries is presented, drawing conclusions on how the shape of the thermoelement affects the coupled phenomena. A specially developed coupled and non-linear finite element research code is run taking into account all the materials of the cell and using symmetries and repetitions. These accurate results are used to validate the analytical ones.

• Journal of Distribution Science
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• v.22 no.8
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• pp.77-86
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• 2024

Purpose: This study investigates the psychological mechanisms of comparison within the design context of retail stores, products, and advertising. The research aims to expand the understanding of comparison psychology, encompassing social, cognitive, perceptual, and self-comparisons and their application in design practices. Research Design, Data, and Methodology: The study employs a comprehensive review of psychological theories related to comparison psychology. They were selected through extensive research on literature pertaining to design psychology and consumer behavior. The research integrates insights from psychology, marketing, consumer behavior, and design theory, supported by various design examples of retail stores, products, and advertising, to demonstrate the practical applications. Results: The findings reveal that comparison psychology significantly impacts consumer preferences and user experiences. For instance, the assimilation effect and prospect theory highlight how comparisons shape value judgments and design perceptions. Practical examples are used to illustrate the profound influence of comparative judgments in design. Conclusion: The study advocates for a "psychologically-informed approach" to design, promoting designs that are not only aesthetically pleasing and functionally sound but also psychologically aligned. By bridging the gap between psychological theories and practical design implementations, the research provides valuable insights for designers, marketers, and psychologists, enhancing the psychological efficacy of design.

• The Korean Journal of Applied Statistics
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• v.23 no.2
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• pp.219-234
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• 2010

In index investing according to KOSPI, we estimate Value at Risk(VaR) from the extreme losses of the daily returns which are obtained from KOSPI. To this end, we apply Block Maxima(BM) model which is one of the useful models in the extreme value theory. We also estimate the extremal index to consider the dependency in the occurrence of extreme losses. From the back-testing based on the failure rate method, we can see that the model is adaptable for the VaR estimation. We also compare this model with the GARCH model which is commonly used for the VaR estimation. Back-testing says that there is no meaningful difference between the two models if we assume that the conditional returns follow the t-distribution. However, the estimated VaR based on GARCH model is sensitive to the extreme losses occurred near the epoch of estimation, while that on BM model is not. Thus, estimating the VaR based on GARCH model is preferred for the short-term prediction. However, for the long-term prediction, BM model is better.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2611-2616
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• 2011

We studied the physical properties of the mercaptopyruvic-acid layer formed on gold surfaces, which has the interactions with the titanium dioxide surface for design of gold- titanium dioxide distribution. Surface force measurements were performed, using the atomic force microscope (AFM), between the surfaces as a function of the salt concentration and pH value. The forces were analyzed with the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory, to evaluate the potential and charge density of the surfaces quantitatively for each salt concentration and each pH value. The difference in the properties reflected the effect of the isoelectric point on the surface forces. The forces were interpreted for the evaluation with the law of mass action and the ionizable groups on the surface. The salt concentration dependence of the surface properties, found from the measurement at pH 8.0, was consistent with the prediction from the law. It was found that the mercaptopyruvic-acid layer had higher values for the surface charge densities and potentials than the titanium dioxide surfaces at pH 8, which may be attributed to the ionized-functional-groups of the mercaptopyruvic-acid layer.

• Proceedings of the Technology Innovation Conference
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• 1996.12a
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• pp.179-195
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• 1996

With current. difficulties in Korean agricultural sector, the biotecilnoiogy is considered as the most important factor to offset the inferiority in the agriculture. New products by using the biotechnology would be commercialized and consumed by both producers and consumers. Before its production and distribution researches on new product should be undertaken in many aspects, especially in terms of economic aspects. Main objectives of this study are to measure the economic value of the new product using the agro-biotechnology, here potato microtubers, and to examine whether the stated preferences theory, the Contingent Valuation Method(CVM), could be accepted in the economic analysis for the new biotech product. Through the demand function derived from the consequences of functional relationship, the consumer's surplus was estimated.

• Bulletin of the Korean Mathematical Society
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• v.48 no.2
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• pp.247-260
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• 2011

Let h be a meromorphic function with few poles and zeros. By Nevanlinna's value distribution theory we prove some new properties on the polynomials in h with the coefficients being small functions of h. We prove that if f is a meromorphic function and if $f^m$ is identically a polynomial in h with the constant term not vanish identically, then f is a polynomial in h. As an application, we are able to find the entire solutions of the differential equation of the type $$f^n+P(f)=be^{sz}+Q(e^z)$$, where P(f) is a differential polynomial in f of degree at most n-1, and Q($e^z$) is a polynomial in $e^z$ of degree k $\leqslant$ max {n-1, s(n-1)/n} with small functions of $e^z$ as its coefficients.

• Journal of Technology Innovation
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• v.5 no.1
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• pp.249-265
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• 1997

With current difficulties in Korean agricultural sector, the biotechnology is considered as the most important factor to offset the inferiority in the agriculture. New products by using the biotechnology would be commercialized and consumed by both producers and consumers. Before its production and distribution, researches on new product should be undertaken in many aspects, especially in terms of economic aspects. Main objectives of this study are to measure the economic value of the new product using the agro-biotechnology, here potato microtubers, and to examine whether the stated peferences theory, the Contingent Valuation Method(CVM), could be accepted in the economic analysis for the new biotech product. Through the demand function derived from the consequences of functional relationship relationship, the consumer's surplus was estimated.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.963-968
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• 2008

For the [$Cr_2(H_2tmp)_2Cl_4$] compound, simplified models with two bridging methoxo ligands have been studied. The influence of the bridging Cr-O-Cr bond angles on the exchange coupling between metal atoms in the model compound has been analyzed by means of density functional calculations with the broken-symmetry approach. Coupling constant calculated for the full structure is in good agreement with the experimentally reported value, confirming the validity of the computational strategy used in this work to predict the exchange coupling in a family of related dinuclear Cr(III) compounds. The calculations indicate a good correlation between the calculated coupling constant and the sum of the squared energy gap of three pairs of metal $t_{2g}$ OMSOs with a limited variation of the Cr-O-Cr angle. The spin density distribution and the mechanism of magnetic coupling interactions are discussed.

• Smart Structures and Systems
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• v.19 no.3
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• pp.309-322
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• 2017

In this paper, the buckling, and free vibration analysis of tapered functionally graded carbon nanotube reinforced composite (FG-CNTRC) micro Reddy beam under longitudinal magnetic field using finite element method (FEM) is investigated. It is noted that the material properties of matrix is considered as Poly methyl methacrylate (PMMA). Using Hamilton's principle, the governing equations of motion are derived by applying a modified strain gradient theory and the rule of mixture approach for micro-composite beam. Micro-composite beam are subjected to longitudinal magnetic field. Then, using the FEM, the critical buckling load, and natural frequency of micro-composite Reddy beam is solved. Also, the influences of various parameters including ${\alpha}$ and ${\beta}$ (the constant coefficients to control the thickness), three material length scale parameters, aspect ratio, different boundary conditions, and various distributions of CNT such as uniform distribution (UD), unsymmetrical functionally graded distribution of CNT (USFG) and symmetrically linear distribution of CNT (SFG) on the critical buckling load and non-dimensional natural frequency are obtained. It can be seen that the non-dimensional natural frequency and critical buckling load decreases with increasing of ${\beta}$ for UD, USFG and SFG micro-composite beam and vice versa for ${\alpha}$. Also, it is shown that at the specified value of ${\alpha}$ and ${\beta}$, the dimensionless natural frequency and critical buckling load for SGT beam is more than for the other state. Moreover, it can be observed from the results that employing magnetic field in longitudinal direction of the micro-composite beam increases the natural frequency and critical buckling load. On the other hands, by increasing the imposed magnetic field significantly increases the stability of the system that can behave as an actuator.

• The Korean Journal of Financial Management
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• v.24 no.3
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• pp.133-152
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• 2007

In this paper, we examine a portfolio selection model in which a safety-first investor maximizes expected return subject to a downside risk constraint. We use the Value-at-Risk as the downside risk measure. We exploit the fact that returns are fat-tailed, and use a semi-parametric method suggested by Jansen, Koedijk and de Vries(2000). We find a more realistic asset allocation than the one suggested by the literature based on the traditional mean-variance framework. For the robustness check, we provide empirical analyses using empirical quantiles. The results highlight that for optimal portfolio selection involving downside risks that are far in the tails of the distribution, our mean-VaR model with a fat-tailed distribution is superior.