• The Korean Journal of Ecology
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• v.8 no.1
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• pp.7-14
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• 1985

Biomass, carbon, nitrogen and phosphorus standing crops of bethic community were estimated at the trophic levels in the intertidal zone of Kum river estuary. Annual mean biomass of zoobenthos was 130.5g/$m^2$, body fraction 26.7g/$m^2$ and shell fraction 103.8 g/$m^3$. Biomass estimated as ash-free dry weight was total 28.9g/$m^2$, body fraction 20.2g/$m^2$ and shell fraction 8.7g/$m^2$ Carbon standing crops of zoobenthos were 15.9gC/$m^2$, in which organic carbon content was 7.0gC/$m^2$ and carbonate carbon was 8.9gC/$m^2$. Production efficiency by carbon standing crops from sediment to herbivores and carnivores and 10.6% and 16.0% in phosphorus, respectively. Annual primary production of benthic algae was crudely estimated to 329g.dw/$m^2$/yr by using the biomass and turn-over rate of benthic algae.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.320-326
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• 2018

In this study, Graphite/Silicon/Carbon (G/Si/C) composites were synthesized to improve the electrochemical properties of Graphite as an anode material of lithium ion battery. The prepared G/Si/C composites were analyzed by XRD, TGA and SEM. Also the electrochemical performances of G/Si/C composites as the anode were performed by constant current charge/discharge, rate performance, cyclic voltammetry and impedance tests in the electrolyte of $LiPF_6$ dissolved inorganic solvents (EC:DMC:EMC=1:1:1 vol%). Lithium ion battery using G/Si/C electrode showed better characteristics than graphite electrode. It was confirmed that as the silicon content increased, the capacity increased but the capacity retention ratio decreased. Also, it was shown that both the capacity and the rate performances were improved when using the Silicon (${\leq}25{\mu}m$). It is found that in the case of 10 wt% of Silicon (${\leq}25{\mu}m$), G/Si/C composites have the initial discharge capacity of 495 mAh/g, the capacity retention ratio of 89% and the retention rate capability of 80% in 2 C/0.1 C.

• Korean Journal of Food Science and Technology
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• v.46 no.4
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• pp.522-525
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• 2014

The effects of temperature and inosine monophosphate (IMP) on the germination of artificially inoculated Bacillus cereus spores in ganjang, doenjang, and gochujang sauces were investigated. The pH and salt concentration of the sauces were as follows: ganjang (4.84, 7.45%), doenjang (4.26, 5.07%), and gochujang (3.54, 3.24%), respectively. Treatment at $40^{\circ}C$ or $80^{\circ}C$ resulted in a B. cereus growth of 0.8 log CFU/g in ganjang sauce; this concentration increased to 2.25 log CFU/g and 1.21 log CFU/g, respectively, when 10 mM IMP was added. Compared with that for ganjang sauce, the germination effect was comparatively lower for doenjang sauce by 10 mM IMP+$40^{\circ}C$ treatment (0.46 log CFU/g) and 10 mM IMP+$80^{\circ}C$ treatment (0.85 log CFU/g). However, no germination effect was noted for gochujang sauce by any treatment in this study. Therefore, the results suggested that pH is an important factor affecting spore germination in sauces.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.37-44
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• 2015

A queueing system with 2 parallel workstations is common in the field. Typically, the workstations have different features in terms of the inter arrival times of customers and the service times for the customers. Computer simulation study on the optimal server allocation for parallel heterogeneous queueing systems with fixed number of identical servers is presented in this paper. The queueing system is optimized with respect to minimizing the weighted system time of the customers served by 2 parallel workstations. The system time formula for the M/M/c systems in Kendall's notation is known. Thus, we first compute the optimal allocation for parallel M/M/c systems, comparing the results with those from the computer simulation experiments, and have the same results. The CETI rule is devised through optimizing M/M/c cases, which allocates the servers based on Close or Equal Traffic Intensities between workstations. Traffic intensity is defined as the arrival rate divided by the service rate times the number of servers. The CETI rule is shown to work for M/G/c, G/M/c queueing systems by numerous computer simulation experiments, even if the rule cannot be proven analytically. However, the CETI rule is shown not to work for some of G/G/c systems.

• Bulletin of the Korean Mathematical Society
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• v.47 no.6
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• pp.1275-1283
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• 2010

If the Wiener-Hopf $C^*$-algebra W(G,M) for a discrete group G with a semigroup M has the uniqueness property, then the structure of it is to some extent independent of the choice of isometries on a Hilbert space. In this paper we show that if the Wiener-Hopf $C^*$-algebra W(G,M) of a partially ordered group G with the positive cone M has the uniqueness property, then (G,M) is weakly unperforated. We also prove that the Wiener-Hopf $C^*$-algebra W($\mathbb{Z}$, M) of subsemigroup generating the integer group $\mathbb{Z}$ is isomorphic to the Toeplitz algebra, but W($\mathbb{Z}$, M) does not have the uniqueness property except the case M = $\mathbb{N}$.

• Journal of the Korean Mathematical Society
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• v.38 no.3
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• pp.623-631
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• 2001

Let $\kappa$ be a real abelian field of conductor f and $\kappa$(sub)$\infty$ = ∪(sub)n$\geq$0$\kappa$(sub)n be its Z(sub)p-extension for an odd prime p such that płf$\phi$(f). he aim of this paper is ot compute the cohomology groups of circular units. For m>n$\geq$0, let G(sub)m,n be the Galois group Gal($\kappa$(sub)m/$\kappa$(sub)n) and C(sub)m be the group of circular units of $\kappa$(sub)m. Let l be the number of prime ideals of $\kappa$ above p. Then, for mm>n$\geq$0, we have (1) C(sub)m(sup)G(sub)m,n = C(sub)n, (2) H(sup)i(G(sub)m,n, C(sub)m) = (Z/p(sup)m-n Z)(sup)l-1 if i is even, (3) H(sup)i(G(sub)m,n, C(sub)m) = (Z/P(sup)m-n Z)(sup l) if i is odd (※Equations, See Full-text).

• Communications of the Korean Mathematical Society
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• v.38 no.1
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• pp.223-234
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• 2023

The main purpose of this paper is to study the lightlike hypersurface (M, $\overline{g}$) of cosymplectic space form $\overline{M}$(c). In this paper, we computed the Gauss and Codazzi formulae of (M, $\overline{g}$) of cosymplectic manifold ($\overline{M}$, g). We showed that we can't obtain screen semi-invariant lightlike hypersurface (SCI-LH) of $\overline{M}$(c) with parallel second fundamental form h, parallel screen distribution and c ≠ 0. We showed that if second fundamental form h and local second fundamental form B are parallel, then (M, $\overline{g}$) is totally geodesic. Finally we showed that if (M, $\overline{g}$) is umbilical, then cosymplectic manifold ($\overline{M}$, g) is flat.

• Journal of Ecology and Environment
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• v.29 no.1
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• pp.23-27
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• 2006

This study was conducted to evaluate forest carbon cycling and soil $CO_2$ efflux rates in a 42-year-old pine (Pinus densiflora) stand located in Hamyang-gun, Korea. Aboveground and soil organic carbon storage, litterfall, litter decomposition, and soil $CO_2$ efflux rates were measured for one year. Estimated aboveground biomass carbon storage and increment in this stand were $3,250gC/m^2\;and\;156gC\;m^{-2}yr^{-1}$, respectively. Soil organic carbon storage at the depth of 30 cm was $10,260gC/m^2$ Mean organic carbon inputs by needle and total litterfall were $176gC\;m^{-2}yr^{-1}\;and\;235gC\;m^{-2}yr^{-1}$, respectively. Litter decomposition rates were faster in nne roots less than 2 mm diameter size ($<220\;g\;kg^{-1}yr^{-1}$) than in needle litter ($<120\;g\;kg^{-1}yr^{-1}$). Annual mean and total soil respiration rates were $0.37g\;CO_2m^{-2}h^{-1}$ and $2,732g\;CO_2m^{-2}yr^{-1}$ during the study period. A strong positive relationship existed between soil $CO_2$ efflux and soil temperature (r=0.8149), while soil $CO_2$ efflux responded negatively to soil pH (r=-0.3582).

• Journal of the Korean Mathematical Society
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• v.36 no.1
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• pp.97-107
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• 1999

Given a C-dynamical system (A, G, $\alpha$) with a locally compact group G, two kinds of C-algebras are made from it, called the full C-crossed product and the reduced C-crossed product. In this paper, we extend the theory of the classical C-crossed product to the C-dynamical system (A, G, $\alpha$) with a left-cancellative semigroup M with unit. We construct a new C-algebra A $\alpha$rM, the reduced crossed product of A by the semigroup M under the action $\alpha$ and investigate some properties of A $\alpha$rM.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.415-418
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• 1999

The characteristics of VRLA (valve regulated Iead-acid) battery with the tubular positive plate and gel type electrolyte were examined as a function of active material filling density. The filling density of positive plate was 3.2 g/mL, 3.4 g/mL, and 3.6 g/mL, respectively. These VRLA batteries were cycled with 100% DOD (depth of discharge) at the $C_5/5$ rate, followed by IU-type recharge with $I_{max}=0.2C_{10}/10$ and a final voltage V=2.40 V/cell. The test was performed in a thermostatic room at $25{\pm}1^{\circ}C$. The result indicated that the initial capacity was independent of active material filling density, i.e., the highest initial capacity was 3.4 g/mL of filling density and the lowest was 3.6 g/mL. On aspect of the cycle-life performance of the VRLA battery, the filling density of 3.6 g/mL was similar to that of 3.4 g/mL in the positive plate, and both were higher than that of 3.2 g/mL. Water-loss and degradation of the VRLA battery were decreased according to an increase of the filling density in the positive plate. The optimum filling density of the active material was 3.4~3.6 g/mL.