• BMB Reports
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• 제38권5호
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• pp.584-590
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• 2005

Glucose 6-phosphate dehydrogenase (EC 1.1.1.49) was purified from Aspergillus aculeatus, a filamentous fungus previously isolated from infected tongue of a patient. The enzyme, apparently homogeneous, had a specific activity of $220\;units\;mg^{-1}$/, a molecular weight of $105,000{\pm}5,000$ Dal by gel filtration and subunit size of $52,000{\pm}1,100$ Dal by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The substrate specificity was extremely strict, with glucose 6-phosphate (G6P) being oxidized by nicotinamide adenine dinucleotide phosphate (NADP) only. At assay pH of 7.5, the enzyme had $K_m$ values of $6\;{\mu}m$ and $75\;{\mu}m$ for NADP and G6P respectively. The $k_{cat}$ was $83\;s^{-1}$. Steady-state kinetics at pH 7.5 produced converging linear Lineweaver-Burk plots as expected for ternary-complex mechanism. The patterns of product and dead-end inhibition suggested that the enzyme can bind NADP and G6P separately to form a binary complex, indicating a random-order mechanism. The enzyme was irreversibly inactivated by heat in a linear fashion, with G6P providing a degree of protection. Phosphoenolpyruvate (PEP), adenosinetriphosphate (ATP), and fructose 6-phosphate (F6P), in decreasing order, are effective inhibitors. Zinc and Cobalt ions were effective inhibitors although cobalt ion was more potent; the two divalent metals were competitive inhibitors with respect to G6P, with $K_i$ values of $6.6\;{\mu}m$ and $4.7\;{\mu}m$ respectively. It is proposed that inhibition by divalent metal ions, at low NADPH /NADP ratio, is another means of controlling pentosephosphate pathway.

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.2032-2039
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• 2005

The lattice Boltzman method (LBM) and the finite difference-based lattice Boltzmann method (FDLBM) are quite recent approaches for simulating fluid flow, which have been proven as valid and efficient tools in a variety of complex flow problems. They are considered attractive alternatives to conventional finite-difference schemes because they recover the Navier-Stokes equations and are computationally more stable, and easily parallelizable. However, most models of the LBM or FDLBM are for incompressible fluids because of the simplicity of the structure of the model. Although some models for compressible thermal fluids have been introduced, these models are for monatomic gases, and suffer from the instability in calculations. A lattice BGK model based on a finite difference scheme with an internal degree of freedom is employed and it is shown that a diatomic gas such as air is successfully simulated. In this research we present a 2-dimensional edge tone to predict the frequency characteristics of discrete oscillations of a jet-edge feedback cycle by the FDLBM in which any specific heat ratio $\gamma$ can be chosen freely. The jet is chosen long enough in order to guarantee the parabolic velocity profile of a jet at the outlet, and the edge is of an angle of $\alpha$=23$^{o}$. At a stand-off distance w, the edge is inserted along the centerline of the jet, and a sinuous instability wave with real frequency is assumed to be created in the vicinity of the nozzle exit and to propagate towards the downstream. We have succeeded in capturing very small pressure fluctuations resulting from periodic oscillation of the jet around the edge.

• Journal of Advanced Marine Engineering and Technology
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• 제32권1호
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• pp.82-93
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• 2008

The flowfield behind two cylinders and flow-induced noise generated from the cylinders in various arrangement are numerically investigated based on the finite difference lattice Boltzmann model with 21 velocity bits. which is introduced a flexible specific heat ${\gamma}$ to simulate diatomic gases like air. In an isolated cylinder with two type of mesh. some flow parameters such as Strouhal number $S_t$ and acoustic pressure ${\Delta}p$ simulated from the solution are given and quantitatively compared with those provided the previous works. The effects of the center-to-center pitch ratio $L_{cc}/d=2.0$ in staggered circular cylinders as shown in Fig. 1 and angles of incidence ${\alpha}=30^{\circ}(T_{cc}/d=0.5)$, $45^{\circ}(T_{cc}/d =0.707)$ and $60^{\circ}\;(T_{cc}/d=0.866)$, respectively, are studied. Our analysis focuses on the small-scale instabilities of vortex shedding, which occurs in staggered arrangement. With the results of drag $C_d$ and lift $C_l$ coefficients and vorticity contours. the mechanisms of the interference phenomenon and its interaction with the two-dimensional vortical structures are present in the flowfields under $Re\;{\le}\;200$. The results show that we successively capture very small pressure fluctuations, with the same frequency of vortex shedding, much smaller than the whole pressure fluctuation around pairs of circular cylinders. The upstream cylinder behaves like an isolated single cylinder, while the downstream one experiences wake-induced flutter. It is expected that, therefore, the relative position of the downstream cylinder has significant effects on the flow-induce noise, hydrodynamic force and vortex shedding characteristics of the cylinders.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권5호
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• pp.2156-2170
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• 2020

This paper presents a fire detection algorithm with a minimal false detection rate, intended for a thermal imaging surveillance environment, whose properties vary depending on temporal conditions of day or night and environmental changes. This algorithm was designed to minimize the false detection alarm rate while ensuring a high detection rate, as required in fire detection applications. It was necessary to reduce false fire detections due to non-flame elements occurring when existing fixed threshold-based fire detection methods were applied. To this end, adaptive flame thresholds that varied depending on the characteristics of input images, as well as the center of gravity of the heat-source and hot-source regions, were analyzed in an attempt to minimize such non-flame elements in the phase of selecting flame candidate blocks. Also, to remove any false detection elements caused by camera shaking, one of the most frequently raised issues at outdoor sites, preliminary decision thresholds were adaptively set to the motion pixel ratio of input images to maximize the accuracy of the preliminary decision. Finally, in addition to the preliminary decision results, the texture correlation and intensity of the flame candidate blocks were averaged for a specific period of time and tested for their conformity with the fire decision conditions before making the final decision. To verify the fire detection performance of the proposed algorithm, a total of ten test videos were subjected to computer simulation. As a result, the fire detection accuracy of the proposed algorithm was determined to be 94.24%, with minimum false detection, demonstrating its improved performance and practicality compared to previous fixed threshold-based algorithms.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1996년도 춘계 학술대회논문집
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• pp.58-67
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• 1996

This paper describes some computational results of various energy and environmental systems using Patankar's SIMPLE method. The specific topics handled in this study are jet bubbling reactor for flue gas desulfurization, cyclone-type afterburner for incineration, 200m tall stack for 500 MW electric power generation, double skin and heat storage systems of building energy saving for the utilization of solar heating, finally turbulent combustion systems with liquid droplet or pulverized coal particle. A control-volume based finite-difference method with the power-law scheme is employed for discretization. The pressure-velocity coupling is resolved by the use of the revised version of SIMPLE, that is, SIMPLEC. Reynolds stresses are closed using the standard $k-{\varepsilon}$ and RNG $k-{\varepsilon}$ models. Two-phase turbulent combustion of liquid drop or pulverized coal particle is modeled using locally-homogeneous, gas-phase, eddy breakup model. However simple approximate models are incorporated for the modeling of the second phase slip and retardation of ignition without consideration of any detailed particle behavior. Some important results are presented and discussed in a brief note. Especially, in order to make uniform exit flow for the jet bubbling reactor, a well-designed structure of distributor is needed. Further, the aspect ratio in the double skin system appears to be one of important factors to give rise to the visible change of the induced air flow rate. The computational tool employed in this study, in general, appears as a viable method for the design of various engineering system of interest.

• 한국세라믹학회지
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• 제35권8호
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• pp.857-863
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• 1998

MLCC(Multilayer ceramic capacitor) 등의 전자 세라믹스 분야에서 폭넓게 이용되는 BaTiO3 분말 제조를 위해 GNP(Glycine-Nitrate process)법을 이용하였다. 일반적인 GNP법과는 달리 출발물질로 카보네이트와 알콕사이드를 도입했고, 연소반응의 산화제 및 출발물질의 용매로써 질산을 사용하였으며, 연소합성시의 연료인 글리신의 첨가량을 달리하여 분말을 합성하였다. 연소합성된 분말의 특성은 helium pycnometer, XRD, N2 흡착을 이용한 BET, 주사전자현미경 등으로 분석하였다. 제조된 전구체 분말은 100$0^{\circ}C$로 하소시에 단일상의 BaTiO3 상으로 전이되었으며, 조성이 1.2인 경우 24m2/g의 높은 비표면적 값을 나타내었다.

• 대한기계학회논문집
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• 제12권5호
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• pp.952-958
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• 1988

본 연구에서는 폭방향 불균일 냉각에 따른 열응력이 판변형 및 잔류응력의 주 요원인이라는 고려하에 냉각중에 압연판의 온도분포 및 열응력을 예측할 수 있는 수치 해석 모델을 구성하였다. 온도와 응력 계산에 상변태 현상을 고려하였으며, 판변형 은 압축성분 열응력에 의한 좌굴현상으로 고려하여 해석하였다.

• 한국농공학회지
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• 제16권4호
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• pp.3600-3610
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• 1974

Experimental work of batch-type dryer was conducted to develop its optimurm operating conditions by analyzing the major factors which affect the drying performance. A laboratory batch-type dryer was constructed and tested for various levels of heated-air rates, and depths of grain deposit. Tong-il rice variety having the initial moisture content of approximaely 23 per cent in wet basis was used for the experiment. The criteria selected for establishing the optimum operating condition were the drying performance rate, the thermal efficiency, and the operational cost of the dryer. The results of the study are summarized as follows: 1. The performance rate of dryer for a specific operating condition was defined as total amount of material dried per hour when the moisture content of grains in the upperlayer reaches to 16 per cent in wet basis. The optimum operating conditions as viewed in the rate of drying performance could be justified by functional realtionship between the depth of grain deposit and air flow rate. In other words, there was a definite depth of grain deposit for a given air-rate which make the dryer performance maximum. The optimum grain depth for the batch-type dryer with 3.3㎡ loading area and with the attached axial fan was about 35cm. 2. The thermal efficiency for the dryer was evaluated by the ratio of the latent heat required to evaporate the grain moisture to the heat input required to raise the ambient air-temperature to 40 degree centigrade. The optimum operating condition as viewed in term of thermal efficiency analyzed was that grater depth and lower air flow-rate may be desirable. This condition is contracted with the optimum condition as viewed by the dryer performance rate. 3. The annual operating cost of batch-type dryer was analyzed for different annual hour of use and for different operation condition. The optimum condition as viewed in terms of operating cost was almost identical to one as viewed in terms of dryer performance rate. Therefore, the most economical use of batch-type dryer for the same annual operating hours can be obtained when the dryer operated in the condition of maximum dryer performance rate. Increasing the annual operating hour may be desirable to cut down the dryer operation cost, since the annual hour of dryer use is much sensitive to the operating cost than any peractical conditions of dryer operation. 4. The most desirable operational condition as justified by combining all the criteria, dryer performance rate, thermal efficiency and annual operating cost, could be concluded to operate the dryer in the condition of maximum performance rate. The condition in general is identical to the lowest operation cost for a given annual operating hour.

• 생태와환경
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• 제54권4호
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• pp.384-389
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• 2021

본 연구는 2020년 10월 23일에 경기도 가평군 설악면에 위치한 청평호에서 수행되었으며, 어군탐지기를 이용해 획득한 자료를 기반으로 어류의 수평 및 수직 분포 패턴을 분석하였다. 어군탐지 조사가 수행된 구간의 총 수면적은 782,853 m²였으며, 수심(water depth, WD)이 10~12 m인 구간이 전체 수면적의 31.7%로 가장 넓게 분포하는 것으로 나타났다. 다양한 WD 구간별로 어류의 개체 밀도 산출 결과, 4~6 m 구간에서 0.98 개체/100 m²로 가장 높게 나타나, 수면적 대비 가장 많은 어류가 분포하는 것으로 확인되었다. Heat map 분석 결과 청평호 구간에서는 가평대교의 우안측에서 어류의 밀도가 가장 높게 나타났으며, 이러한 수평 분포 특성에서 특별한 경향성은 확인할 수 없었다. 어류의 수직분포 분석 결과, 어류가 관측된 수심(Fish depth, FD)이 6 m 이하인 경우가 전체 관측 대비 86.6%로 나타났다. 수심 대비 어류의 관측 수심(Relative height, RH) 분석 결과, 수심이 깊어질수록 어류가 상대적으로 표층에 분포하는 경향성을 확인할 수 있었다. 이와 관련해서는 수체의 수심별 수온 차이 등 다양한 원인이 있을 것으로 예상되며 추가적인 연구가 필요하다.

• Korean Chemical Engineering Research
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• 제47권6호
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• pp.747-754
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• 2009

본 연구에서는 $1,000^{\circ}C$에서 24시간 열처리된 활성탄에서 다이옥신과 유사구조를 갖는 o-DCB(ortho-dichlorobenzene)의 등온흡착식을 실험을 통하여 구하였고, 분자모사를 통하여 예측하였다. 실험으로 분석된 활성탄의 분자식 및 작용기 비율을 바탕으로 초기 활성탄 기본구조를 설계한 후, COMPASS(condensed-phase optimized molecular potentials for atomistic simulation studies) force field를 이용하여 이 구조를 최적화하였다. 최적화된 활성탄 분자구조에서 공극률, 비표면적, 및 입자밀도의 모사결과는 실험값과 비교되었고, 이들에 대한 실험과 모사결과의 오차는 각각 7.62, 3.79, 2.80%를 보여주었다. 통계 열역학적 방법인 GCMC(Grand Canonical Monte Carlo) 기법을 이용하여, 최적화된 활성탄 구조에서 온도에 따른 o-DCB의 등온흡착 상수값을 예측하였으며, 이 모사결과는 실험값과 비교될 때, 3% 이하의 오차를 보였다. o-DCB의 흡착특성을 바탕으로 확인되어진 활성탄 구조에서 다이옥신의 일종인 2,3,7,8-TCDD(tetrachlorodibenzo-p-dioxin) 등온흡착상수, 흡착열, 그리고 기공확산계수를 최종적으로 구함으로서, 실험적으로 구하기 힘든 맹독성 잔류성 유기물질의 흡착특성을 분자모사기법을 통하여 예측하였다.