• Membrane and Water Treatment
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• 제14권2호
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• pp.85-93
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• 2023

Membrane separation is widely used for several applications such as water treatment, membrane reactors and climate change. Cross-linked organic-inorganic hybrid polyvinylidene fluoride (PVDF) / Tetraethyl orthosilicate (TEOS) was adopted for the preparation of optimized hollow membrane (HFM) for membrane distillation or other low pressure separators for mechanical properties and permeability under varying pretreatment schemes. HFMs were prepared on semi-pilot membrane fabrication system. Novel adopted post-treatment schemes involved soaking in glycerol, magnesium sulphate (MgSO₄), sodium hypochlorite (NaOCl), and isopropanol for different durations. All fibers were characterized for morphology using a scanning electron microscope (SEM), surface roughness using atomic force microscope (AFM), elemental composition by examining Energy Dispersive Spectroscopy (EDS), water contact angle (CA°) and porosity. The performance of the fibers was evaluated for pure water permeation flux (PWF). Post-treatment with MgSO₄ gave the highest both tensile modulus and flux. Assessment of properties and performance revealed comparable results with other organic-inorganic separators, HF or flat. In spite of few reported data on post treatment using MgSO₄ in presence of TEOS, this proves the potential of low cost treatment without negative impact on other membrane properties. The flux is also comparable with hypochlorite which manifests substantial precaution requirements in actual industrial use.The relatively high values of flux/bar for sample treated with TEOS, post treated with MgSO₄ and hypochlorite are 88 and 82 LMH/bar respectively.

• 플랜트 저널
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• 제6권4호
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• pp.56-62
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• 2010

This study investigated characteristics of the post-weld heat treatment of SA213-T23, which was developed for water wall of the ultra super critical power boiler. The temperature of post weld heat treatment should be $730^{\circ}C$ or higher to reduce hardness of the deposit metal and heat affected zone. Coincidently, the temperature should remain $760^{\circ}C$ or lower to prevent hardness of the base metal from dropping. Hardness decline of deposit metal was trivial according to time when the holding time of heat treatment at $740^{\circ}C$ of post-weld heat treatment gradually increased from initial 15 minutes.

• Membrane and Water Treatment
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• 제15권2호
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• pp.79-88
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• 2024

Modification of Polyvinylidene fluoride (PVDF) hollow fiber membranes (HFMs) characteristics and performance were investigated via post treatment using different oxidants. sodium hypochlorite (NaOCl), hydrogen peroxide (H₂O₂) and potassium persulfate (KPS). Fourier transform infrared (FTIR) and Proton nuclear magnetic resonance (¹H-NMR) results revealed no structural differences after post treatment. Cross-sectional micrographs show finger-like structures at the outer and inner walls of the HFMs and sponge-like structures in middle, where NaOCl and KPS post treated fibers exhibited a decrease in finger-like structures in addition to aggregates appearing on the surface, consequently leading to an increase in the surface roughness (Ra) from 48 nm to 52.8nm and 56 nm, respectively. Hydrogen peroxide post treatment only was observed to decrease the water contact angle from 98° to 81.4°. It was also observed that the elongation at break and the modulus deceased after NaOCl post treatment from 34.5 to 28.5% and from 19.3 Mpa to 16.6 Mpa, respectively. Moreover, pure water flux after H₂O₂ post treatment increased from 87.8 LMH/bar to 113 LMH/bar at 0.45 bar, while no changes were detected for the methylene blue dye rejection (74%) between raw and hydrogen peroxide post treated fibers at the same pressure. According to the findings hydrogen peroxide post treated PVDF HFMs have the most uniform surfaces, with almost no alterations in structural and mechanical properties or porosities with enhanced hydrophilicity and pure water flux maintaining appropriate rejection. Therefore, it is considered an efficient surface modifying agent for UF/NF membranes or low-pressure separators.

• Journal of Welding and Joining
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• 제11권4호
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• pp.103-111
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• 1993

Recently, several high-tensile steels(e.g. 80kg and above, $2^{1/4}Cr$-1Mo)having good quality to high temperature and pressure-resistance are widely used to construct petroleum-plant and pressure vessel of heat or nuclear-power plant. However, in the steels, reheating crack at grain boundaries of the heat affected zone(HAZ) occures during post welding heat treatment(PWHT)to remove welding residual stress. In order to study theoretically the characteristics of reheating crack created by PWHT, the computer program of three-dimensional thermal-elasto-plasto-creep analysis based on finite element method are developed, and then the mechanical behavior(history of creep strain accumulation and stress relaxation, etc)of welded join in thick plate during PWTH is clarified by the numerical results.

• 한국응용곤충학회지
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• 제41권4호
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• pp.293-298
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• 2002

살선충제 2종(카두사포스, 포스치아제이트)을 땅콩뿌리혹선충(Meloidogyne arenaria)이 감염된 참외 재배 포장에 정식 전처리(전처리)및 재배중 처리(후처리)하고(각 1.8 g a. i./6$\m^2$), 이들의 뿌리혹선충 방제효과, 참외 수량에 미치는 영향 및 참외 과일내 농약잔류량에 대하여 비교 조사하였다. 살선충제가 뿌리혹선충 밀도에 미치는 효과는 5월에 가장 뚜렷하였다. 살선충제 처리구의 선충밀도는 무처리구 밀도의 10-65%이었으며 살선충제 중에서는 포스치아제이트(P=0.003)가, 처리방법에서는 전처리+후처리에서 효과가 높았다(밀도 90% 감소). 살선충제 처리구는 무처리구에 비하여 5월 수량은 평균 23%(11-38%), 6월 수량은 평균 39%(2-65%), 총수량으로는 평균 31%(12-46%)가 증수되는 경향으로 유의성은 낮았으나(P ＝ 0.085) 수량차이는 많았다. 카두사포스는 과일내 농약 잔류량이 0.008ppm이하로 후처리에 문제가 없었으나 포스치아제이트는 후처리 약 30일 후 참외 잔류허용 기준치(0.2ppm)를 초과하는 0.26ppm이 검출되었고, 그 외의 기간에 수확한 참외에서도 0.12ppm이상 높게 검출되었다. 살선충제 후처리에 의한 뿌리혹선충 방제법은 농약잔류위험성, 후반기의 낮은 참외 가격, 농약 비용, 안전농산물에 대한 소비자의 요구, 휴경 효과 등을 종합적으로 고려할 때 바람직하지 않은 것으로 생각된다.

• The Plant Pathology Journal
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• 제20권4호
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• pp.258-263
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• 2004

Ripe fruit of pepper (Capsicum annuum) showed resistance to Colletotrichum gloeoporioides, but unripe fruit was susceptible. We previously isolated the PepTLP gene that induced in both unripe and ripe fruit by fungal infection and wound, and only in ripe fruit by jasmonic acid (JA) treatment. To examine further regulation of PepTLP, the action of specific agonist and antagonists of known signaling effector on the .PepTLP expression by fungal infection, wound, and JA was investigated. A similar dephosphorylation event negatively activated all the PepTLP expression in the ripe fruit by fungal infection, wound, and JA. The induction of PepTLP expression by wound is differentially regulated via phosphorylation and dephosphorylation step during pre- and post-ripening, respectively. In addition, the induction of PepTLP expression in the ripe fruit by wound and JA is differentially regulated via dephosphorylation and phosphorylation step, respectively. Only both wound and JA treatment has synergistic effect on the PepTLP expression in the unripe fruit. Both SA and JA treatments on the unripe fruit, and both wound or JA and SA on the ripe fruit could not do any effect on the expression of PepTLP. These results suggest that the induction of PepTLP expression is differentially regulated via complex regulatory system against fungal infection, wound, and JA treatment during pre- and post-ripening of pepper fruit.

• 한국작물학회지
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• 제26권2호
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• pp.179-184
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• 1981

본 시험은 1980년도에 전남대학교 시험포장에서 수행된 것으로서, Metribuzin의 처리시기에 따른 품종반응차이를 알기 위하여 광교외의 5대두품종과 Pre-sowing 외에 4처리 시기를 공시하여 작물의 초기생육반응을 조사하여 다음의 결과를 얻었다. 1. 공시품종내에서는 약제에 대한 저항성 차이가 뚜렷하지 않았다. 2. 품종차이보다는 약제처리시기에 따른 반응차이가 헌저하였으며, 대부분 대두품종의 저항성 크기는 E. Post-emg.< L.Post-emg $\ll$re-sowing=Control의 순으로 컸다. 3. Metribuzin의 약해 Symptom은 주당엽수 < 초장 $\ll$주당분지수의 순으로 뚜렷한 감소를 보이는 특징이었다. 4. 우리나라 대두품종에 대한 Metribuzin의 사용은 Pre-sowing이나 Pre-emg.가 추천되며, 특히 Pre-sowing에 대한 토양혼화법 연구와 단제보다는 혼용처리의 이점을 찾을 필요가 있다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제16권3호
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• pp.197-207
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• 2016

It is very important to maintain a constant chlorine concentration in the post chlorination process, which is the final step in the water treatment process (hereafter WTP) before servicing water to citizens. Even though a flow meter between the filtration basin and clear well must be installed for the post chlorination process, it is not easy to install owing to poor installation conditions. In such a case, a raw water flow meter has been used as an alternative and has led to dosage errors due to detention time. Therefore, the inlet flow to the clear well is estimated by a time series neural network for the plant without a measurement value, a new residual chlorine meter is installed in the inlet of the clear well to decrease the control period, and the proposed modeling and controller to analyze the chlorine concentration change in the well is a neuro fuzzy algorithm and cascade method. The proposed algorithm led to post chlorination and chlorination improvements of 1.75 times and 1.96 times respectively when it was applied to an operating WTP. As a result, a hygienically safer drinking water is supplied with preemptive response for the time delay and inherent characteristics of the disinfection process.

• Journal of Plant Biology
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• 제17권1호
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• pp.15-21
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• 1974

The most commonly grown economical and flue-cured tobacco cultivar Yellow Special A was used in pot-culture tests in order to study Ethrel (2-chloroethyl phosponic acid) effects on accelerating maturity of tobacco leaves in relation to the most adequate level of the chemical useful for field growing, nitrogen level in soil for the most pronounced response, and the most suitable spray period during the growth stages of pre-, post- and topping periods. The following conclusions, thus, were obtained from the present studies; 1. 500ppm Ethrel spray was reconfirmed to be adequate in the practical applications, although the extent of yellow-ripening of tobacco leaves was increased as the Ethrel level increased. The highest leevel treated resulted in causing chemically damaged lesions on leaves and early defoliation. 2. Ethrel-treated leaves showed deeper yellowish tinge to them than those without treatment, while different levels of the chemcial had less influence on the tinge. 3. An adequate level of nitrogen supply to plants favored the Ethrel response, whereas either very low or high level of nitrogen in the soil lowered the chemical effect on accelerating the yellow-ripening. When carbohydrates versus total nitrogen ratio became relatively high, the condition brought out some outstanding Ethrel effects. 4. Chlorophyll level of leaves increased as soil applications of nitrogen level increased, and that also increased carotenoid level of the tobacco leaves. Ethrel-treated leaves showed deeper orange tinge than those without treatment, while the highest level of nitrogen application showed the deepest orange tinge to tobacco leaves. 5. Pre-topping treatment (12 days before topping and flowering) resulted in almost no Ethrel response, and that treatment right on the day of topping, showed response of yellow-leaf ripening at nearly bottom-half leaves of a tobacco plant. The post-topping treatment (12 days after topping) made plants showing full response of Ethrel from bottom to the top leaves of tobacco plant in accelerating the leaf maturity. 6. The extent of Ethrel responses on accelerating yellow-ripening of tobacco leaves was discussed for the modifying influences brought about by certain environmental factors. Discussions were also made about the possible practical applications (particularly for pre-rice planting) and quality difference that may be caused by such growth environments.

• 한국압력기기공학회 논문집
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• 제11권1호
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• pp.33-38
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• 2015

The effects of post weld heat treatment(PWHT) on the mechanical properties of 2.25Cr-1Mo steels were investigated. As the PWHT temperature or holding time increased, the strength of low alloy steels progressively decreased due to softening process. After the conventional PWHT, the strength was larger than the minimum value of materials specification. The Charpy impact energy was hardly affected by the conventional PWHT. The trend of mechanical properties was analyzed in terms of tempering parameter. Most materials replaced from a power plant met the requirements of materials specification except for one heat. Same heat of materials with low impact energy were attributed to the voids formed during casting process.