• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1997년도 Proceedings International Workshop on New Video Media Technology
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• pp.31-36
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• 1997

Bit allocation is a critical problem in video encoding such as MPEG. To improve the quality of the reconstructed sequence for a given bit rate, the assigned target bits for a group of pictures (GOP) must be allocated to each picture efficiently. In this paper, we derive a target bit allocation algorithm for more efficient rate control, by assuming that the average rate-distortion curve for an input source is logarithmic. This target bit allocation is based on Shannon's rate-distortion theory, which deals with the minimization of source distortion subject to a channel rate constraint. Simulation results show that the proposed target bit allocation algorithm provides better performance than the one in MPEG-2 Test Model 5 (TM5).

• Journal of Microbiology
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• 제44권6호
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• pp.583-590
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• 2006

In this study, an organic solvent tolerant bacterial strain was isolated. This strain was identified as Pseudomonas sp. strain S5, and was shown to degrade BTEX (Benzene, Toluene, Ethyl-Benzene, and Xylene). Strain S5 generates an organic solvent-tolerant lipase in the late logarithmic phase of growth. Maximum lipase production was exhibited when peptone was utilized as the sole nitrogen source. Addition of any of the selected carbon sources to the medium resulted in a significant reduction of enzyme production. Lower lipase generation was noted when an inorganic nitrogen source was used as the sole nitrogen source. This bacterium hydrolyzed all tested triglycerides and the highest levels of pro-duction were observed when olive oil was used as a natural triglyceride. Basal medium containing Tween 60 enhanced lipase production to the most significant degree. The absence of magnesium ions ($Mg^{2+}$) in the basal medium was also shown to stimulate lipase production. Meanwhile, an alkaline earth metal ion, $Na^+$, was found to stimulate the production of S5 lipase.

• 지구물리와물리탐사
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• 제21권1호
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• pp.1-7
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• 2018

전기탐사 2차원 모델링에서는 다수의 파수영역 전위를 계산하고 이를 푸리에 역변환하여 공간영역 전위를 계산한다. 푸리에 역변환은 여러 개의 서로 다른 파수에서의 파수영역 전위를 사용하여 수치적으로 얻어진다. 적분의 정확도를 향상시키기 위하여 파수의 크기에 따라 적분 구간을 지수 근사와 대수 근사 구간으로 분할하는 방법이 널리 사용되고 있다. 푸리에 역변환에는 크게 구간 적분법과 가우스 적분법이 사용되고 있다. 그러나 이들 방법은 송수신 간격을 고려하지 못하므로 송수신 간격에 따른 오차를 피할 수 없다. 특히 송수신 간격이 매우 작거나 클 경우 오차가 급격하게 증가하는 문제점을 가지고 있다. 이 연구에서는 송수신 간격을 고려하여 가우스 좌표값 및 가중값을 적용하는 새로운 수치 적분법을 개발하였다. 반무한 공간에 대한 수치 실험 결과, 개발된 수치 적분법은 송수신 간격에 관계없이 0.4% 이하의 정밀도를 나타내었다.

• Journal of information and communication convergence engineering
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• 제12권3호
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• pp.135-139
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• 2014

Opportunistic routing was originally introduced in various multihop network environments to reduce the number of hops in such a way that, among the relays that decode the transmitted packet for the current hop, the one that is closest to the destination becomes the transmitter for the next hop. Unlike the conventional opportunistic routing case where there is a single active S-D pair, for an ad hoc network in the presence of fading, we investigate the performance of parallel opportunistic multihop routing that is simultaneously performed by many source-destination (S-D) pairs to maximize the opportunistic gain, thereby enabling us to obtain a logarithmic gain. We first analyze a cut-set upper bound on the throughput scaling law of the network. Second, computer simulations are performed to verify the performance of the existing opportunistic routing for finite network conditions and to show trends consistent with the analytical predictions in the scaling law. More specifically, we evaluate both power and delay with respect to the number of active S-D pairs and then, numerically show a net improvement in terms of the power-delay trade-off over the conventional multihop routing that does not consider the randomness of fading.

• Environmental Engineering Research
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• 제22권4호
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• pp.417-425
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• 2017

Indonesia is known as the largest oil palm producer in the world. However, along with the production, it generates wastes and pollution that caused the environmental problem in surrounding areas. Previous researchers reported that the high palm oil mill effluent (POME) concentration inhibited microalgae growth. However, the inhibition factor was not clearly explained by using kinetic model. This study presents kinetic models of Botryococcus braunii (B. braunii) cultivated on POME wastewater under different turbidity condition. Results showed that the growth model of Zwietering was closely suitable with experimental results. It was found that B. braunii was able to consume organic carbon from the POME wastewater on the logarithmic model. A modified kinetic model of Monod Haldane described the influence of turbidity and chemical oxygen demand on the cultivation. Turbidity of POME medium inhibited the growth rate at KI 3.578 and KII 179.472 NTU, respectively. The Lipid (39.9%), and carbohydrate (41.03%) were found in the biomass that could be utilized as biofuel source.

• 한국물환경학회지
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• 제30권1호
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• pp.8-15
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• 2014

In this study, regression equation was analyzed to estimate non-point source (NPS) pollutant loads in orchard area. Many factors affecting the runoff of NPS pollutant as precipitation, storm duration time, antecedent dry weather period, total runoff density, average storm intensity and average runoff intensity were used as independent variables, NPS pollutant was used as a dependent variable to estimate multiple regression equation. Based on the real measurement data from 2008 to 2012, we performed correlation analysis among the environmental variables related to the rainfall NPS pollutant runoff. Significance test was confirmed that T-P ($R^2=0.89$) and BOD ($R^2=0.79$) showed the highest similarity with the estimated regression equations according to the NPS pollutant followed by SS and T-N with good similarity ($R^2$ >0.5). In the case of regression equation to estimate the NPS pollutant loads, regression equations of multiplied independent variables by exponential function and the logarithmic function model represented optimum with the experimented value.

• BMB Reports
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• 제38권5호
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• pp.545-549
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• 2005

Acidithiobacillus ferrooxidans is one of the most important bacterium used in bioleaching, and can utilize $Fe^{2+}$ or sulphide as energy source. Growth curves for Acidithiobacillus ferrooxidans under phosphate starvation and normal condition have been tested, showing lag, logarithmic, stationary and aging phases as seen in other bacteria. The logarithmic phases were from 10 to 32 hours for Acidithiobacillus ferrooxidans cultivated with normal cultivating condition and from 20 to 60 hrs for Acidithiobacillus ferrooxidans cultivated phosphate starvation. Differences of protein patterns of Acidithiobacillus ferrooxidans growing in case of normal or phosphate starvation were separately investigated after cultivation at $30^{\circ}C$ by the analysis of two-dimensional gel electrophoresis (2-DE), matrix-assisted laser desorption/ionization (MALDI)-Mass spectrometry. There were total 6 protein spots identified, which were Recombination protein recA, RNA helicase, AP2 domain-containing transcription factor, NADH dehydrogenase I chain D, Hyothetical protein PF1669, and Transaldolase STY3758. From the 6 identified protein spots, 3 proteins were found to be decreased in expression at the cultivating condition of phosphate starvation, while another three upregulated.

• 천문학논총
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• 제30권2호
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• pp.235-236
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• 2015

Microlensing can be seen as a version of strong gravitation lensing where the separation angle of the image formed by light deflection by a massive object is too small to be seen by a ground based optical telescope. As a result, what can be observed is the change in light intensity as function of time; the light curve. Conventionally, the intensity of the source is expressed in magnitudes, which uses a logarithmic function of the apparent flux, known as the Pogson formulae. In this work, we compare the magnitudes from the Pogson formulae with magnitudes from the Asinh formulae (Lupton et al. 1999). We found for small fluxes, Asinh magnitudes give smaller deviations, about 0.01 magnitudes smalller than Pogson magnitudes. This result is expected to give significant improvement in detection level of microlensing light curves.

• 대한기계학회논문집
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• 제16권5호
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• pp.933-942
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• 1992

본 연구에서는 이상류 동축 노즐의 미립화 기구를 규명하기 위한 기초단계로 20˚의 증류수를 사용하여 이상류 동축노즐의 평균액적 직경에 미치는 공급유량의 영 향을 직접사진 촬영법을 사용하여 규명하고자 한다.

• Applied Biological Chemistry
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• 제13권1호
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• pp.43-50
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• 1970

석유탄화수소 이용미생물연구의 일환으로서 미생물에 의한 세포단백질생산의 목적으로 전국각지 135 개지역에서 주유소 세차장의 유침(油浸)토양을 비롯 석탄, 논밭, 하천토양등 242종을 수집하고 이시료로부터 석유탄화수소를 유일한 유기탄소원으로 이용하는 효모 468균주를 분리하였고 분리된 효모균주의 증식율(增殖率)을 screening 하여 우수균주를 선정하였다. 선정된 효모에 대하여 동정(同定) 및 배양 최적 조건의 검토 그리고 효모균체의 성분분석을 한 결과 다음과 같다. 1) 석유탄화수소 이용효모중 90.8%가 주유소및 세차장등 유침토양에서 나머지 10%가 석탄, 작토(作土) 하천토양에서 분리되였다. 2) 분리선정된 가장 우수한 효모균주는 주유소의 유침토양에서 분리됐고 Candida curvata HY-69-19로 동정되었다. 3) 분리선정된 Candida curvata HY-69-19는 optimum pH 5.0, optimum temperature $28^{\circ}C$, aerobic condition에서 균증식율이 컸다. 4) Candida curvata HY-66-19는 유기탄소원으로 petroleum fraction 중 비중이 0.8654이고 비점이 $268.9^{\circ}C$ 이상의 fraction인 heavy gas oil을 잘이용하며 무기질소원으로$(NH_2)_2CO$가 증식율과균체세포생산에 최적임을 알었다. 5) 분리선정된 이효모는 heavy gas oil 배지에서 lag phase 18시간, logarithmic growth phase 24시간${\sim}$42시간 사이며 이 때의 generation time은 3.8${\sim}4.5$시간이었다. 6) 분리선정된 이 효모는 heavy gas oil 및 $(NH_2)_2CO$ 배지로 54시간 pH 를 6시간마다 조정하면서 진탕배양하여 300mg/ml. H.G,0.의 건조균체를 생산하였다. 7) Candida curvata HY-69-19의 균체성분은 조단백질 40.25%, 조지방 14.81%,탄수화물 24.32% 회분 10.63%이었다.