• Journal of Microbiology and Biotechnology
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• v.23 no.12
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• pp.1708-1716
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• 2013

Conventional molecular detection methods cannot distinguish between viable and dead Escherichia coli O157 cells. In this study, the loop-mediated isothermal amplification (LAMP) method combined with propidium monoazide (PMA) treatment was developed to selectively detect viable E. coli O157 cells. Four primers, including outer primers and inner primers, were specially designed for the recognition of six distinct sequences on the serogroups (O157) of the specific rfbE gene of the E. coli O157 genome. PMA selectively penetrated through the compromised cell membranes and intercalated into DNA. Amplification of DNA from dead cells was completely inhibited by $3.0{\mu}g/ml$ PMA, whereas the DNA derived from viable cells was amplified remarkably within 1 h by PMA-LAMP. Exhibiting high sensitivity and specificity, PMA-LAMP is a suitable method for evaluating the inactivation efficacy of slightly acidic electrolyzed water in broth. PMA-LAMP can selectively detect viable E. coli O157 cells. This study offers a novel molecular detection method to distinguish between viable and dead E. coli O157 cells.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.511-515
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• 2007

The yield of oil was rapidly increased at $440^{\circ}C$ compared to $400^{\circ}C$ and $420^{\circ}C$ when the isothermal pyrolysis of waste ship lubricating oil was carried out in tubular type reactor, and pyrolysis was almost finished within 30 min. The yield of gas was decreased depending on the reaction temperature in which that of solid was not much changed. Pyrolysis experiments of waste ship lubricating oil were carried out with used ZSM-5 produced from a petrochemical process. The yield of gas was highly increased in the case of used ZSM-5 and fresh ZSM-5 compared to the case without catalyst. The produced oil and gas were almost constant for fresh ZSM-5 and used ZSM-5 at the same reaction temperature. In the reaction temperature $400{\sim}440^{\circ}C$, the selectivity of $C_5-C_{11}$ was two times higher with fresh ZSM-5 and used ZSM-5 than the case without catalyst.

• Carbon letters
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• v.18
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• pp.18-23
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• 2016

Polyacrylonitrile (PAN)-based carbon fibers have high specific strength, elastic modulus, thermal resistance, and thermal conductivity. Due to these properties, they have been increasingly widely used in various spheres including leisure, aviation, aerospace, military, and energy applications. However, if exposed to air at high temperatures, they are oxidized, thus weakening the properties of carbon fibers and carbon composite materials. As such, it is important to understand the oxidation reactions of carbon fibers, which are often used as a reinforcement for composite materials. PAN-based carbon fibers T300 and T700 were isothermally oxidized in air, and microstructural changes caused by oxidation reactions were examined. The results showed a decrease in the rate of oxidation with increasing burn-off for both T300 and T700 fibers. The rate of oxidation of T300 fibers was two times faster than that of T700 fibers. The diameter of T700 fibers decreased linearly with increasing burn-off. The diameter of T300 also decreased with increasing burn-off but at slower rates over time. Cross-sectional observations after oxidation reactions revealed hollow cores in the longitudinal direction for both T300 and T700 fibers. The formation of hollow cores after oxidation can be traced to differences in the fabrication process such as the starting material and final heat treatment temperature.

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.841-851
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• 1996

In a recent investigation, the formation of bainite phase in direct-quenched low carbon non heat-treated steel was reported. In this study the effects of bainite phase on the mechanical properties of direct-quenched microalloying steels were investigated. By isothermal transformation at $480^{\circ}C$ for 7 sec., volume fraction of bainite lath was 15~20%, and the UTS and impact energy were increased. In this case $B_{ll}$ and $B_{lll}$ type bainite was observed and the fractography of impact test specimen showed a ductile fracture tendency. Isothermal transformation for 100sec., yielded 30% volume fraction of granular bainite and the mechanical properties were decreased. The f ractography of impact test specimen showed a brittle fracture tendency. The addition of Mo was more effective than B for improving impact energy because amounts of boron aditions were restricted to considerably lower levels, typically 10~ 30ppm. From this study, it is predicted that 15~20% volume fraction of lath bainite on the direct quenching process is procduced by addition of Mo up to 1.2wt. % and controlling the finish forging proc¬ess at $1000^{\circ}C$ and using oil as direct quenching media. This will improve mechanical properties of the direct- quenched steel.

• Metals and materials international
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• v.24 no.6
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• pp.1202-1212
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• 2018

The effects of Nickle (Ni) addition on bainitic transformation and property of ultrahigh strength bainitic steels are investigated by three austempering processes. The results indicate that Ni addition hinders the isothermal bainite transformation kinetics, and decreases the volume fraction of bainite due to the decrease of chemical driving force for nucleation and growth of bainite transformation. Moreover, the product of tensile strength and total elongation (PSE) of high carbon bainitic steels decreases with Ni addition at higher austempering temperatures (220 and $250^{\circ}C$), while it shows no significant difference at lower austempering temperature ($200^{\circ}C$). For the same steel (Ni-free or Ni-added steel), the amounts of bainite and RA firstly increase and then decrease with the increase of the austempering temperature, resulting in the highest PSE in the sample austempered at temperature of $220^{\circ}C$. In addition, the effects of austempering time on bainite amount and property of high carbon bainitic steels are also analyzed. It indicates that in a given transformation time range of 30 h, more volume of bainite and better mechanical property in high carbon bainitic steels can be obtained by increasing the isothermal transformation time.

• Korean Journal of Veterinary Service
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• v.38 no.3
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• pp.145-153
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• 2015

In this study, we developed a loop-mediated isothermal amplification (LAMP) with hydroxynaphtol blue dye (HNB) for rapid and direct visual detection of porcine circovirus 2 DNA with high sensitivity and specificity. The LAMP was completed in 40 min at $63^{\circ}C$, and the results of the LAMP can be confirmed by naked eye without any detection process. The sensitivity of the LAMP was 10-fold higher than that of the commercial PCR (cPCR) and real time PCR (rPCR) previously reported. In clinical application, the PCV2 detection rate of the LAMP was the same on porcine tissue samples (75.0%, 36/48) between porcine blood samples (75.0%, 39/52). The PCV2 detection rate (75.0%) of LAMP was higher than those of the cPCR and rPCR (67.3%, 35/52) in blood samples. In conclusion, the LAMP developed in the study could be an useful alternative method for the detection of PCV2 in the swine disease diagnostic laboratories.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.474-477
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• 2009

In this paper, flow stress of Al6061 is obtained by compression test in the range of temperature from $300^{\circ}C$ to $550^{\circ}C$ and effective strain-rate from 0.1/s to 20.0/s. The flow stress information is used to simulate an aluminum hot forging process. Non-isothermal simulation is carried out by a rigid-thermoviscoplastic finite element method. The predictions are compared with the experiments in terms of the deformed shape of material.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.48-53
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• 1993

In this paper, it is shown that chaotic nonlinear chemical process can be controlled based on the Poincare map based control algorithm. An isothermal autocatalytic CSTR, which has chaotic dynamics, is successfully controlled and period 2 orbit is generated in a normal chaotic region with small perturbation of the control parameter.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.37-41
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• 2005

The curing of thermoset resin is accompanied with the changes in chemical and physical properties. The cure monitoring techniques can be designed by tracing these property changes. This paper presents the cure monitoring technique with fiber optic sensors to detect the change of refractive index during the polymerization process of engineering epoxy resin. The fiber optic sensor system was developed to measure the reflection coefficient at the interface between the fiber optic and the resin. The correlation between the sensor output and the degree of cure was performed following Lorentz-Lorenz law. The isothermal data from the sensors are compared with the data from differential scanning calorimeter.

• The Korean Journal of Rheology
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• v.1 no.1
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• pp.71-79
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• 1989

임계연신비로 특징지어지는 비등온 방사공정에서의 Draw Resonance 발생을, White 의 변형속도에 따라 변하는 물질의 이완시간 모델에 의한 convected Maxwell 유체의 방사 모형을 사용해서 연구했다. 임계연신비의 계산에는 다른 연구자들이 이용하는 통상의 복잡 한 수치계산인 eigenvalue 방법을 쓰지 않고 전파하는 동적 waves 에 근거한 간단한 Hyun 의 이론을 사용했다. 그 결과 Staton Number와 냉각 공기온도로서 나타내지는 방사공정의 냉각이 공정을 안정시킨다는 것이 밝혀졌다. 다시 말해서 연신점도가 변형후화인 유체이거 나 변형박화인 유체이거난 상관없이 항상 Stanton Number가 켜지거나 또는 냉각공기온도 가 낮아질수록(즉냉각효과가 커질 때) 임계연신비가 커지는 것이다(단변형박화 dvcp의 빌부 구간을 제외하고) 한편 Draw Resonacnce 에 미치는 냉각의 효과는 무차원 이완시간(a Weissenberg Number 혹은 a Deborah number)이 커질수록 작아진다는 것도 발견됐다. 이 것은 process Time 이 작아지면 열전달이 작아지기 때문이다. 이러한 내용들은 다른 연구 자들의 결과와도 잘 부합된다.