• 아시안잔디학회지
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• 제9권2호
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• pp.119-129
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• 1995

Decomposition rates of glucose, starch, spinach leaves and litters in forests are calculated by equation dC dt=-kC(Co-1nC), dC- dt=$-kC^2$, and Olson's negative exponential decay model.dC dt = - kC =-kC(Co - InC) showed a very close fit to decomposition of the organic matters in cultural media by purified microorganisms and dC dt=$-kC^2$ to decomposition of the litters in forests. Key words: Organic matters, Cultural media, Glucose, Starch, Leaves, Litters.

• Food Science and Biotechnology
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• 제18권4호
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• pp.1013-1018
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• 2009

Several rheological terms were introduced to estimate the properties of cooked noodles with different starch content using tensile tests. Ring-shaped specimens were prepared by connecting both ends of the noodle strip before cooking. Hencky strain and rate, as well as true stress were applied in constant deformation tests. The elastic region on the curves of strain vs. stress was not clearly identified. Strain hardening in the subsequent plastic region was more prominent in low-starch noodles. Elongational viscosities at lower strain rates were used to differentiate noodles with different starch content, representing the dominant effect of protein content in the range of lower strain rates. In stress relaxation tests, the reciprocal of Peleg's constant $K_1$ (initial decay rate) and $K_2$ (asymptotic level) increased and decreased respectively, with an increase in starch content. This indicated that addition of starch contributed to the noodles becoming viscous liquid rather than elastic solid.

• Communications for Statistical Applications and Methods
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• 제6권3호
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• pp.849-860
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• 1999

This paper addresses the issue of estimating regression function with errors in variables using wavelets. We adopt a nonparametric approach in assuming that the regression function has no specific parametric form, To account for errors in covariates deconvolution is involved in the construction of a new class of linear wavelet estimators. using the wavelet characterization of Besov spaces the question of regression estimation with Besov constraint can be reduced to a problem in a space of sequences. Rates of convergence are studied over Besov function classes $B_{spq}$ using $L_2$ error measure. It is shown that the rates of convergence depend on the smoothness s of the regression function and the decay rate of characteristic function of the contaminating error.

• Journal of Ecology and Environment
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• 제43권4호
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• pp.376-384
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• 2019

Background: Nutrient release during litter decomposition was investigated in Vitex doniana, Terminalia avecinioides, Sarcocephallus latifolius, and Parinari curatellifolius in Makurdi, Benue State Nigeria (January 10 to March 10 and from June 10 to August 10, 2016). Leaf decomposition was measured as loss in mass of litter over time using the decay model W_t/W₀ = e-^{kd t}, while $Kd=-{\frac{1}{t}}In({\frac{Wt}{W0}})$ was used to evaluate decomposition rate. Time taken for half of litter to decompose was measured using T₅₀ = ln ²/k; while nutrient accumulation index was evaluated as $NAI=(\frac{{\omega}t\;Xt}{{\omega}oXo})$. Results: Average mass of litter remaining after exposure ranged from 96.15 g, (V. doniana) to 78.11 g, (S. lafolius) in dry (November to March) and wet (April to October) seasons. Decomposition rate was averagely faster in the wet season (0.0030) than in the dry season (0.0022) with P. curatellifolius (0.0028) and T. avecinioides (0.0039) having the fastest decomposition rates in dry and wet seasons. Mean residence time (days) ranged from 929 to 356, while the time (days) for half the original mass to decompose ranged from 622 to 201 (dry and wet seasons). ANOVA revealed highly significant differences (p < 0.01) in decomposition rates and exposure time (days) and a significant interaction (p < 0.05) between species and exposure time in both seasons. Conclusion: Slow decomposition in the plant leaves implied carbon retention in the ecosystem and slow release of CO₂ back to the atmosphere, while nitrogen was mineralized in both seasons. The plants therefore showed effectiveness in nutrient cycling and support productivity in the ecosystem.

• 한국약용작물학회지
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• 제23권6호
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• pp.431-438
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• 2015

Background : This study was conducted to determine out the effect of storage temperature on the quality of fresh ginseng (Panax ginseng C. A. Meyer) during distribution. Methods and Results : Fresh ginseng was washed, packed in $30{\mu}m$ low density polyethylene (LDPE) film, then stored at 0, -2 and $-4^{\circ}C$. After 4 weeks of storage, ginseng was then stored at $5^{\circ}C$, as a simulation of the distribution process. Ginseng stored at $-4^{\circ}C$ showed higher respiration rate, ethylene production and electrolyte conductivity during the distribution phase than those stored at 0 and $-2^{\circ}C$. Decay and browning rate rapidly increased following 3 weeks of distribution in samples stored $-4^{\circ}C$. However ginseng stored $-2^{\circ}C$, which is below freezing point, for 4 weeks did not show the physiological change or quality deterioration. Ginsenoside contents decreased during storage for all plant, but did not differ significantly between storage temperatures. Conclusions : Storage at temperatures below $-2^{\circ}C$ can negatively affect respiratory characteristics and electrolyte leakage and increase quality deterioration and decay rates during distribution.

• 대한기계학회논문집
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• 제16권6호
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• pp.1150-1155
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• 1992

본 연구에서는 제철소 열연공정의 냉각효율 개선을 위한 기초연구로 수행되었 다. 전열면의 초기온도가 900.deg. C이상일 때 층류 냉각방식에 의한 고온강판의 냉각특 성에 영향을 주는 모든 인자를 엄밀히 고려하는 것은 매우 어려운 일이다.따라서 본 연구에서는 노즐과 고온면 사이 거리(L), 유량(Q), 냉각 초기온도 등을 실제 작업 조건에 가깝게 변화시켜 가면서 수냉반경의 변화를 중심으로 전열면의 냉각 특성을 해 석하였다.

• 한국광학회지
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• 제10권5호
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• pp.386-390
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• 1999

서로 대칭인 두 광기능성 그룹들 (4-cyanoazobenzene groups)을 포함하는 측쇄형 액정 고분자(liquid crystalline polymalonic esters, PCN)에 이광파혼합을 이용하여 소거가 가능한 편광 홀로그램을 기록하였다. 기록된 회절격자의 회절효율을 측정하고, 기록광의 세기에 대한 격자의 기록 특성, 암실 상태에서의 감쇠 및 광에 의한 소거 특성을 조사하였다. 측정결과, 복굴절$\Delta$n은 약6.5$\times$10-2;로 Fe:LiNbO3, Ce:BaTiO3 등의 무기결정에 비해 10~100배 정도 높게 측정되었으며, 감쇠곡선도 1시간 동안 4.3$\times$10-5%의 감쇠를 나타냄으로서 정보저장소자로서의 응용 가능성을 보였다.

• 천문학회보
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• 제43권1호
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• pp.56.1-56.1
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• 2018

Tidal disruption events (TDEs) provide evidence for quiescent supermassive black holes (SMBHs) in the centers of inactive galaxies. TDEs occur when a star on a parabolic orbit approaches close enough to a SMBH to be disrupted by the tidal force of the SMBH. The subsequent super-Eddington accretion of stellar debris falling back to the SMBH produces a characteristic flare lasting several months. The theoretically expected bolometric light curve decays with time as proportional to $t^{-5/3}$. However, the light curves observed in most of the optical-UV TDEs deviate from the $t^{-5/3}$ decay rate especially at early time, while the light curves of some soft-X-ray TDEs are overall in good agreement with the $t^{-5/3}$ law. Therefore, it is required to construct the theoretical model for explaining these light curve variations consistently. In this paper, we revisit the mass fallback rates analytically and semi-analytically by taking account of the structure of the star, which is simply modeled by the polytrope. We find the relation between a polytropic index and the power law index of the mass fallback rate. We also discuss whether and how the decay curves, which we derived, fit the observed ones.

• 농업과학연구
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• 제40권3호
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• pp.191-196
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• 2013

This study was conducted to investigate the effect of temperature during transportation and continuing shelf-life on fruit quality and the occurrence of physiological disorder to set up the appropriate exportation temperature condition in Asian pear (Pyrus pyrifolia Nakai) 'Hanareum'. In the experiment of simulated exportation headed for USA, the fruits transported at $1^{\circ}C$ showed less weight loss than those of $5^{\circ}C$. Market temperature appeared as a key factor for keeping freshness of exported pear fruits rather than transportation temperature. Quality factors such as high flesh firmness and low incidence of fruit rot and physiological disorders including core breakdown and pithiness were attained at the fruits maintained at $18^{\circ}C$. Approximately two times higher incidence of physiological disorders and of fruit decay rates were observed in the fruits distributed at $25^{\circ}C$ than the those of $18^{\circ}C$. Therefore, temperature management during marketing resulted as an important factor for maintaining fruits quality in the process of pear fruit exportation.

• Journal of Ecology and Environment
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• 제37권1호
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• pp.13-19
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• 2014

The effect of different turnover time of water on the decomposition of emergent macrophyte litter (Zizania latifolia Griseb.) was investigated using a microcosm experiment. Microcosm treatment represented different turnover time of water; 1, 2, 4 and 8 weeks. The litterbags from each treatment were retrieved every 2 weeks until the 8th week and the water simultaneously sampled with the litterbag. The dry weight and the content of major cations in the litter, and the content of available N, P, and major cations in the water were analyzed. Dry weight loss after 8 weeks indicated the lower decay rates under the condition of short turnover time of water. Major cations from the litter and the water showed that the leached amounts of K and Mg from the litter were highest in the 2nd week and dramatically decreased from the 4th week. The dynamics of available nitrogen and phosphorus in the water showed that as the water turnover time was getting longer, the amounts of available nitrogen and phosphorus remained higher. These results suggest that wetlands with longer turnover time of water could maintain the increased nitrogen and phosphorus and no outflow of the nutrients could cause eutrophication problem.