• Asian Journal of Turfgrass Science
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• v.9 no.4
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• pp.331-342
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• 1995

An investigation was performed to reveal the removal rates of organic constituents of the litters in a Phragmithea longivalvis grassland in a Delta of the Nakdong River, The removal rates of the inorganic and organic materials are determined by the mathematical models. The removal rates and time required to decay up to a percentage of each organic constituent were calculated using these new models. The removal rates of cold water soluble fractions, other carbohydrates, hot water soluble fractions, cellulose, crude fat, lignin and crude protein were 2.67, 1.39, 1.25, 1.02, 0.92, 0.49 and 0.47, respectively, The periods required to reach half time to the steady state of the removal and accumulation for cold water soluble fractions, other carbohydrates, hot water soluble fractions, cellulose, crude fat, lignin and crude protein of the litter were 0.26, 0.50, 0.55, 0.68, 0.75, 1.41 and 1.48 years, respectively.

• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.57-66
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• 1997

Successful energy conservation and good indcfor air quality (IAQ) are highly dependent on ventilation system. Air filtration is a primary solution of indoor air control strategies in terms of reducing energy consumption and improving ihdoor air quality. A conventional system with bypass filter, as it is called variable-air-volume/bypass filtration system (VAV/BPFS), is a variation of the conventional variable air volume (VAV) systems, which is designed to eliminate indoor air pollutant and to save energy. Bypass filtration system equipped with a high-efficiency particulate filter and carbon absorbent provides additional cleaned air into indoor environments and maintain good IAQ for human health. The objectives of this research were to compare the relative total decay rate of indoor air pollutant concentrations, and to develop a mathematical model simulating the performance of VAV/BPFS. All experiments were performed in chamber under the controlled conditions. The specific conclusions of this research are: 1. The VAV/BPFS system is more efficient than the VAV system in removing indoor air pollutant concentration. The total decay rates of aerosol, and total volatile organic compound (TVOC) for the VAV/BPFS system were higher than those of the conventional VAV system. 2. IAQ model predictions of each pollutant agree closely with the measured values. 3. According to IAQ model evaluation, reduction of outdoor supply air results in decreased dilution removal rate and on increased bypass filtration removal rate with the VAV/BPFS. As a results, we recommends the VAV/BPFS as an alternative to conventional VAV systems.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.59-64
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• 2002

The photocatalytic decolorization of the Rhodamine B (RhB) was studied using a UV/TiO$_2$ reactor. Yakuri titanium dioxide(anatase) was used as the suspended photocatalyst and proved to be effective for decolorization irradiated with UV light (254 mm). The photocatalyzed dioxide concentrations, light intensity and air flow rates. In 0.01 mM RhB, color could be completely photodegraded after 3 hours. Absorption spectrum of an aqueous solution containing RhB showed a continued diminution of the RhB concentration in the solution bulk : concomitantly, no new absorption peaks appeared. This confirmed the decolorization of RhB, i.e., the break up of the chromopore. The optimum loaded titanium dioxide for the decolorization was 0.75 g/(equation omitted). The light intensity showed exponential decay with distance. The decay of light intensity of RhB solution showed different tendency from TiO$_2$. These results suggested that the photocatalytic decolorization of dyes may be available method for decolorizing in wastewater.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.271-276
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• 2002

The energy relaxation dynamics of the lowest excited singlet and triplet states of the Zn(II)porphyrin monomer and its directly linked arrays were comparatively investigated with increasing the number of porphyrin moieties. While the fluorescence decay rates and quantum yields of the porphyrin arrays increased with the increase of porphyrin units, their triplet-triplet (T-T) absorption spectra and decay times remained almost the same. The difference in the trends of energy relaxation dynamics between the excited singlet and triplet states has been discussed in view of the electronic orbital configurations.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.881-885
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• 2014

Photophysics of 10-hydroxybenzo[h]quinoline (HBQ) has been in controversy, in particular, on the nature of the electronic states before and after the excited state intramolecular proton transfer (ESIPT), even though the dynamics and mechanism of the ESIPT have been well established. We report highly time resolved fluorescence spectra over the full emission frequency regions of the enol and keto isomers and the anisotropy in time domain to determine the accurate rates of the population decay, spectral relaxation and anisotropy decay of the keto isomer. We have shown that the ~300 fs component observed frequently in ESIPT dynamics arises from the $S_2{\rightarrow}S_1$ internal conversion in the reaction product keto isomer and that the ESIPT occurs from the enol isomer in $S_1$ state to the keto isomer in $S_2$ state.

• Journal of Ecology and Environment
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• v.35 no.2
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• pp.99-109
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• 2012

Litterfall dynamics in forests are assessed by estimating biomass production and decomposition. However, there have been few studies on how litter dynamics impact the health and management of ecosystems. Here, a new approach to measure and assess ecosystem function is presented based on conventional methods using littertraps, litterbags, and the mass on the forest floor. To assess the status of litter dynamics, the decay rate (k) was estimated from a litterbag experiment, and removal rates ($k_i$) were determined from mass balance on the forest floor at 21 sites on three mountains in South Korea. The $k_3$ (organic mass ratio of $O_i$ and $O_e+O_a$ + A horizons in November) values in an equilibrium state in South Korea were within the range of $k{\pm}0.174$ when considering the annual variation of litterfall production. This study also suggests that sampling sites for these types of studies should be in the middle, not at the ends, of steady slopes on the forest floor.

• Journal of the Korean Mathematical Society
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• v.55 no.6
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• pp.1423-1433
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• 2018

This paper is concerned about several quasilinear elliptic systems with m-Laplacians. According to the Liouville theorems of those systems on ${\mathbb{R}}^n$, we obtain the singularity estimates of the positive $C^1$-weak solutions on bounded or unbounded domain (but it is not ${\mathbb{R}}^n$ and their decay rates on the exterior domain when ${\mid}x{\mid}{\rightarrow}{\infty}$. The doubling lemma which is developed by Polacik-Quittner-Souplet plays a key role in this paper. In addition, the corresponding results of several special examples are presented.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.200-204
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• 2012

In engineering hydrology, an estimation of precipitation loss is one of the most important issues for successful modeling to forecast flooding or evaluate water resources for both surface and subsurface flows in a watershed. An accurate estimation of precipitation loss is required for successful implementation of rainfall-runoff models. Precipitation loss or hydrological abstraction may be defined as the portion of the precipitation that does not contribute to the direct runoff. It may consist of several loss elements or abstractions of precipitation such as infiltration, depression storage, evaporation or evapotranspiration, and interception. A composite loss rate model that combines four loss rates over time is derived as a lumped form of a continuous time function for a storm event. The composite loss rate model developed is an exponential model similar to Horton's infiltration model, but its parameters have different meanings. In this model, the initial loss rate is related to antecedent precipitation amounts prior to a storm event, and the decay factor of the loss rate is a composite decay of four losses.

• Asian Journal of Turfgrass Science
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• v.10 no.2
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• pp.151-157
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• 1996

Samples from the L, F, H and $A_1$ horizons of the Phragmites communis, Miscanthus sacchariflorus, Scirpus tabernaemontani and Typha angustata grassland were collected in Paldangho and the removal rates of ritrogen were investigated. The removal rates of nitrogen of the litters were 0.85 in P.communis, 0.56 in M sacchariflorus, 0.45 in T. angustata and 0.31 in S. tabernaemontani The time required to decay 50, 95, 99 percent of the steady state levels and turnover values of nitrogen on the grassland floor were 0.81, 3.53, 5.89 years in the P. communis, 1.23, 5.32, 8.86 years in the M sacchariflorus, 1.54, 6.68, 11.13 years in the S. tabernaemontani and 2.22, 9.63, 16.04 years in the T. angustata Key words: Removal rate, Accumulation, Paldangho, Nitrogen, Phragmites communis, Miscanthus sacchariflorus, Scirpus tabernaemontani, Typha angustata.

• Journal of the Korean Solar Energy Society
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• v.25 no.3
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• pp.37-45
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• 2005

Higher requirement of advanced building design code and the development of construction technique have resulted in more thermal and air tight buildings. This has caused the sick building syndrome in a indoor air quality has been relatively getting worse. A new concept with a solar fresh air heating and electrostatic precipitator or called as STCC(Solar Transpired Collector and Cyclone) has been proposed to solve this IAQ issue. This paper describes the assessment study of STCC system under different outdoor airflow rates. The experiment was carried out under real condition with 30CMM STCC system test facility. Incense smoke was used to study the particle concentration decay trends under outdoor airflow rates 0CMM, 10CMM, 20CMM, 30CMM, with applied voltages of 5kV and 15kV for collecting and discharging electrodes of an Electrostatic Precipitator. Result shows that the particle decay increases by increasing the outdoor airflow rates. The collection efficiency, dust cleaning effectiveness(P) and application area calculation result comparisons have also been studied. This factors could be used to estimate how a dust of indoor air quality(IAQ) and removed for a building space with a STCC system.