• 대한수의학회지
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• 제39권4호
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• pp.765-771
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• 1999

Unlike most Escherichia coli strains, E coli O157 : H7 didn't ferment sorbitol within 24h of incubation and showed a negative reaction for $\beta$-glucuronidase. We developed a new medium for the rapid isolation of E coli O157 : H7 using sorbitol MacConkey agar with cefixime, potassium tellurite and 4-methylumbelliferyl-${\beta}$-D-glucuronide (MUG) as a primary plating medium. The addition of $20{\mu}g/ml$ of vancomycin in enrichment broth for E coli O157 : H7 inhibited lots of Gram positive bacteria. Three strains (10.3%) of 29 non-O157 E coli strains and 3 strains (8.3%) of 36 Salmonella spp were inhibited at the $0.05{\mu}g/ml$ of cefixime and 23 strains (79.3%) of 29 non-O157 E coli strains and 12 strains (33.3%) of 36 Salmonella spp were inhibited at the $2.0{\mu}g/ml$ of potassium tellurite. But none of the E coli O157 : H7 was affected at these concentration. The addition of MUG at $100{\mu}g/ml$ level to sorbitol MacConkey agar with cefixime and potassium tellurite (CTM-SMAC) aided in the rapid isolation of E coli O157 : H7 from samples by checking sorbitol-negative and $\beta$-glucuronidase negative phenotypes simultaneously. In conclusion, inoculation of a positive in the O157 screening test from enrichment broth on CTM-SMAC appeared to be a rapid, cost-effective and sensitive method for the isolation of E coli O157 : H7.

• Applied Biological Chemistry
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• 제47권4호
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• pp.379-383
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• 2004

Bacillus sp. 유래 ${\beta}-mannanase$의 brown copra meal에 대한 기질 특이성을 규명하기 위하여 정제효소 150 ml를 0.5% 기질에 $50^{\circ}C$, 24 hrs 가수분해후 TLC, FACE로 비교 검토한 결과 2종류의 galactosyl mannooligosaccharide로 구성되어 1차 activated carbon column chromatography을 이용해 250 ml/hr 유속으로 tube당 50ml씩 ethanol $0{\sim}30%$ linear gradient로 당을 분리하였다. Activated carbon column chromatography에 의한 당용액 0.2 ml와 5% phenol 0.2 ml를 가하여 혼합 후 $Conc.H_2SO_4$ 1 ml를 가하여 혼합한 후 20분간 방치하여 490 nm로 흡광도를 측정하여 TLC로 pattern을 검토한 후 $Gal^3Man_4$ 및 DP 7의 galactosyl manooligosaccharide의 fraction을 회수하여 2차 activated carbon column chromatography를 이용해 1차와 동일한 조전에서 분리 회수하여 중합도 5는 $Gal^3Man_4(63-mono-{\alpha}-D-galactopyranosyl-{\beta}-mannotetraose)$로 동정되었고, 중합도 7은 현재 동정중에 있다. Bifidobacterium속 균주(B. longum, B. bifidum)에 대한 생육활성을 비교 검토하기 위하여 MRS media에서 탄소원을 dextrose대신에 조제된 $Gal^3Man_4$를 첨가후 측정한 결과 $Gal^3Man_4$이 첨가되지 않은 MRS broth에 비해 생육촉진 활성을 보였다. 특히 B. longum에 대해서는 $Gal^3Man_4$를 dextrose대체 탄소원으로 처리시 10배의 생육활성이 증가하였다.

• 동력기계공학회지
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• 제14권5호
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• pp.5-9
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• 2010

본 연구는 수정 오일러 법칙을 이용한 봉의 열전달문제를 엄밀해와 수치해를 수치해석적 해법을 이용해 비교한 것이다. 경계조건으로는 열전도 및 대류가 동시에 존재하는 경우의 모델을 가정하여 계산하였고, 봉의 길이가 원주방향에 비해 상당히 길다고 가정하여 1차원으로 지배방정식을 정리하여 2차 상미분방정식을 유도하여 계산을 수행하였다. 계산을 수행한 결과 적절한 초기 추측값인 ${\beta}$값을 정의하면 오일러의 방정식으로도 충분히 만족할만한 결과를 얻을 수 있다는 것을 알았고, 지수함수 형태의 유도 상관식이 엄밀해와 ${\pm}1%$ 범위 내에서 일치한다는 결과를 얻었다.

• 대한환경공학회지
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• 제28권3호
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• pp.240-248
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• 2006

본 연구에서는 선행연구를 통하여 개발된 고도처리 공정의 현장적용을 용이하게 하기 위하여 이를 개조한 retrofitting 공정을 제안하였으며, 제안된 공정을 $50m^3$/일 규모의 pilot plant 운전을 통하여 현장 평가하였다. 또한 pilot plant 내에서 미생물의 배양 상태를 확인하기 위하여 FISH 법을 이용하여 세균 군집구조를 조사하였다. 제안된 retrofitting 공정은 배양조를 별도로 건설하지 않음으로써 16%($60,000m^3$/일 규모 고도처리시설 도입 기준)의 초기건설비를 절감할 수 있는 것으로 평가되었으며, 동절기를 포함한 장기간의 pilot plant 운전을 통하여 수처리 효율과 유지관리 측면에서 현장적용성이 우수한 것으로 사료되며 방류수질 기준을 만족하는 것으로 평가되었다. 또한 pilot plant와 대조군(A2/O 공정, B 하수처리장)에서 총세균수는 큰 차이가 없으나, pilot plant의 bioreactor에 의해서 세균 군집 변화가 다르게 나타났다. 우점종은 주로 하수처리에서 중요한 역할을 하는 토양 미생물이 속한 ${\beta}$-proteobacteria group이고, bioreactor 유출수에서 유입수 대비 $25{\sim}607%$ 증가하는 것으로 확인되었으며, 이렇게 증가된 ${\beta}$-group의 미생물은 시스템 내에서 일정 농도를 유지하는 것으로 확인되었다.

• 한국재료학회지
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• 제26권4호
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• pp.173-181
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• 2016

In order to use coal tar pitch (CTP) as a raw material for carbon fibers, it should have suitable properties such as a narrow range of softening point, suitable viscosity and uniform optical properties. In this study, raw CTP was modified by heat treatment with three types of polymer additives (PS, PET, and PVC) to make a spinnable pitch for carbon fibers. The yield, softening point, C/H ratio, insoluble yield, and meso-phase content of various modified CTPs with polymer additives were analyzed by changing the type of polymer additive and the heat treatment temperature. The purpose of this study was to compare the properties of CTPs modified by polymer addition with those of a commercial CTP. After the pitch spinning, the obtained green fibers were stabilized and carbonized. The properties of the respective fibers were analyzed to compare their uniformity, diameter change, and mechanical properties. Among three polymer additives, PS220 and PET261 pitches were found to be spinnable, but the carbon fibers from PET261 showed mechanical properties comparable with those of a commercial CTP produced by an air-blowing method (OCI284). The CTPs modified with polymer additive had higher ${\beta}$-resin fractions than the CTP with only thermal treatment indicating a beneficial effect of carbon fiber application.

• 한국해양공학회지
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• 제28권5호
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• pp.371-377
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• 2014

In this study, the hydrodynamic characteristics of various types of jack-up legs for a wind turbine installation vessel were analyzed. Using the modified Morison equation, the wave and current excitation forces on the jack-up legs were calculated. A modal analysis was performed to predict the dynamic responses for various types of jack-up legs. The Newmark-beta time integration scheme was used to solve the equation of motion in waves in the time domain. The maximum displacement and maximum bending stress were computed for four different types of legs, and their results were compared to select an optimum leg type. Finally, a six-leg jack-up rig with the selected optimal legs was modeled, and its natural period and hydrodynamic behaviors were evaluated.

• Bulletin of the Korean Chemical Society
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• 제25권3호
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• pp.377-381
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• 2004

Chiral separation of aryalcohols such as 1-phenyl-propanol, 1-phenyl-2-proanol, and 2-phenyl-1-propanol by capillary electrophoresis has been optimized using the overlapping resolution mapping (ORM) scheme. Three critical parameters of the electrophoretic media, i.e. phosphate concentration, sulfated ${\beta}$-cyclodextrin (CD) concentration and pH, were chosen for optimization. The working ranges were initially presumed by 7 preexperiments. Further optimization was carried out by another seven experiments within the narrow working ranges. From the final overlapping resolution mapping all peak pairs, the area of maximum separations were located. Using the conditions of a point in this area, we found that the target compounds were a baseline separated within 30 min. The maximum separation conditions of arylalcohols were a chiral selector concentration of 5.4%, a phosphate concentration of 28 mM, and a pH of 5.0.

• 한국해양공학회지
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• 제12권3호통권29호
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• pp.19-30
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• 1998

In this paper, the dynamic analysis of a dolphin system for mooring a floating structure such as barge mounted plant is studied. The characteristics of the soil-pile system are simplified by a set of equivalent spring elements at the mudline. To evaluate the equivalent spring constants, the finite difference method is used. Since the characteristics of the soil-pile system are nonlinear in case of soft foundation, the nonlinear dynamic analysis technique is needed. The Newmark $beta$ method incorporating the modified Newton-Raphson method(initial stiffness method) is used. A numerical analysis is performed on two mooring dolphin systems on soft foundation and rock foundation. In case of the rock foundation, the characteristics are found to be nearly linear, so the linear dynamic analysis may be sufficient to consider the foundation effect. But in case of soft foundation, the non-linearity of the foundation appears to be very signigicant, so the nonlinear dynamic analysis si needed.

• Korean Chemical Engineering Research
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• 제55권3호
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• pp.287-295
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• 2017

Using nanotechnology, magnetic nanoparticles of iron oxide were produced via co-precipitation method and followed modification with organic compounds. In the next step, functionalized monomer was provided via coupling ${\beta}$-cyclodextrine and allylamine onto modified magnetic nanoparticles. These nanoparticles were used to establish the adsorption rate of celecoxib. Magnetic nanoparticles are modified by (3-mercaptopropyl)trimethoxysilane. Nano-adsorbent was characterized by analytical and spectroscopic methods, such as Fourier transform infrared spectroscopy, elemental analysis, thermo-gravimetric analysis, and transmission electron microscopy (TEM). Laboratory parameters, such as the kinetics of adsorption isotherms, pH, reaction temperature and capacity were optimized. Finally, by using this nano-adsorbent in the optimized condition, extraction of celecoxib from biological samples as urine, drug matrix and blood plasma was carried out by high performance liquid chromatography with sensitivity and high accuracy.

• Structural Engineering and Mechanics
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• 제58권6호
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• pp.1127-1143
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• 2016

The pounding phenomenon in adjacent structures happens in severing earthquakes that can cause great damages. Connecting neighboring structures with active and semi-active control devices is an effective method to avoid mutual colliding between neighboring buildings. One of the most important issues in control systems is applying online control force. There will be a time delay if the prose of producing control force does not perform on time. This paper proposed a time-delay compensation method in coupled structures control, with semi-active Magnetorheological (MR) damper. This method based on Newmark's integration is adopted to mitigate the time-delay effect. In this study, Lyapunov's direct approach is employed to compute demanded voltage for MR dampers. Using Lyapunov's direct algorithm guarantees the system stability to design a controller based on feedback. Because of the strong nonlinearity of MR dampers, the equation of motion of coupled structures becomes an involved equation, and it is impossible to solve it with the common time step methods. In present paper modified Newmark-Beta integration based on the instantaneous optimal control algorithm, used to solve the involved equation. In this method, the response of a coupled system estimated base on optimal control force. Two MDOF structures with different degrees of freedom are finally considered as a numeric example. The numerical results show, the Newmark compensation is an efficient method to decrease the negative effect of time delay in coupled systems; furthermore, instantaneous optimal control algorithm can estimate the response of structures suitable.