• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.10
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• pp.575-582
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• 2009

The optimum rotation speed of a desiccant rotor is studied theoretically based on a theoretical solution to the heat and mass transfer processes in the desiccant rotor. A simple correlation equation for the optimum rotation speed is derived to show the effects of various parameters including the thermo-physical properties, the geometric dimension, and the operating condition of the desiccant rotor. The theoretical result is compared with existing experimental data to validate the linearization and simplification included in the solution procedure. Based on the theoretical solution, the effects of major parameters on the optimum rotation speed are studied and the fundamental mechanism of the influences is investigated.

• Journal of Bio-Environment Control
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• v.2 no.1
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• pp.1-8
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• 1993

Experimental and theoretical analyses were carried out to investigate the heat exchange characteristics of the nutrient solution cooling system utilizing ground water. The material of heat exchanger used in the experiment was polyethylene and the cross-flow type was adapted in which nutrient solution was mixed and ground water unmixed. For the exchanger surface area of 0.33$m^2$ and flow rates of ground water of 1-6$\ell$/min, NTU(number of transfer units) and effectiveness of experimental heat exchanger were 0.1-0.45 and 10-35％, respectively. Therefore these results showed that the hydroponic greenhouse of 1,000$m^2$(300 pyong) with the ground water of 10$m^2$/day could cover about 55-70％ of maximum cooling load in summer.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1757-1762
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• 2006

A solvent sublation using salphen as a ligand was studied and applied for the determination of trace Ni(II), Co(II) and Cu(II) in water samples. The fundamental study was investigated by a solvent extraction process because the solvent sublation was done by extracting the floated analytes into an organic solvent from the aqueous solution. The salphen complexes of Ni(II), Co(II) and Cu(II) ions were formed in an alkaline solution of more than pH 8 and then they were extracted into m-xylene. It was known that the each metallic ion formed 1 : 1 complex with the salphen and the logarithmic values of extraction constants for the complexes were 3.3 5.1 as an average value. Based on the preliminary study, the procedure was fixed for the separation and concentration of the analytes in samples. Various conditions such as the pH of solutions, the influence of $NaClO_4$, the bubbling rate and time of $N_2$ gas, and the type of organic solvent were optimized. The metal-salphen complexes could be extracted into m-xylene from the solution of more than pH 8, but the pH could be shifted to acidic solution of pH 6 by the addition of $NaClO_4$. In addition, the solvent sublation efficiency of the analytes was increased by adding $NaClO_4$. The recovery of 97-115% was obtained in the spiked samples in which given amounts of 0.3 mg/L Ni(II), 0.8 mg/L Co(II) and 0.04 mg/L Cu(II) were added.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.11 no.2
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• pp.227-230
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• 2006

• 한국가스학회:학술대회논문집
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• 1998.09a
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• pp.199-202
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• 1998

• Proceedings of the Korean Statistical Society Conference
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• 2003.05a
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• pp.31-36
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• 2003

Using a short time expansion of the fundamental solution of heat equation by analysis of Wiener functional with the help of Malliavin calculus, we obtain the asymptotic expansion of the mean distance of Brownian motion on Riemannian manifolds.

• Bulletin of the Korean Mathematical Society
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• v.37 no.2
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• pp.303-316
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• 2000

The Cauchy problem for degenerate parabolic equations with absorption is studied. We prove the existence of a fundamental solution. Also a Harnack type inequality is established and the existence and uniqueness of initial trace for nonnegative solutions is shown.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.6
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• pp.205-210
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• 1983

This paper presents a steady-state computer solution of the fundamental semiconductor one-dimensional transport equations, describing a single (metal-semiconductor) contact device, involving only one type of charge carrier. The computations are conveniently made by the

• The Mathematical Education
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• v.21 no.3
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• pp.25-28
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• 1983

In this paper we examine some properties of spectral measures and try to establish a fundamental theorem on the existence of the solution of a generalized Volterra equation in a Hilbert space as the results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.417-425
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• 2007

The differential quadrature method(DQM) is applied to computation of eigenvalues of the equations of motion governing the free out-of-plane vibration for circular curved beams including the effects of rotatory inertia and transverse shearing deformation. Fundamental frequencies are calculated for the members with clamped-clamped end conditions and various opening angles. The results are compared with exact solutions or numerical solutions by other methods for cases in which they are available. The DQM provides good accuracy even when only a limited number of grid points is used.