• Resources Recycling
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• v.23 no.1
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• pp.48-57
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• 2014

In this study, we have investigated the influence of the nature of solvent on the grafting reaction of maleic anhydride onto polyethylene wax obtained as a by-product in a high density polyethylene plant. The results show that the grafting ratio in xylene as a solvent was higher than toluene. This is because xylene has excellent monomer solubility, swelling property and miscibility. It has been also observed that grafting degree shows an initial jump in percentage of grafting with increasing amount of solvent, from 0% v/w to 200% v/w giving maximum grafting in 200% v/w and then slightly decreases on further increase in the amount of solvent and becomes almost constant. It can be also seen that gel content was not formed under the use of solvent. It means that solvent prevented cross-linking reaction due to chain transfer reactions to solvent molecules. Studies of melt viscosity at $140^{\circ}C$ showed that viscosity increased after grafting of maleic anhydride onto polyethylene wax.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.307-311
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• 2003

2-mass system is generally used as controller of the variable-speed to transfer electromotion power to mechanical load such as industrial robot, driving parts of electric vehicle, rolling machine system of steel plant and driving parts of elevator. In this case, PI controller is often used as a velocity controller because of simplicity of system. But PI control algorithm is not enough for obtaining the control characteristics required for this system. To solve this problem, 2-mass system based on the PID controller derives the optimum PID parameters by pole assignment and estimation of the ITAE performance index. In this case, the system have tenacious properties about disturbance, but it causes extreme overshoot and vibration because of rapidly output of controller in early transient response about desired value. And if speed control system is applied by 2-DOF parameter ${\alpha}$, a temporary value, we must induce most suitable parameter by complicate pole assignment and estimation of the ITAE performance index whenever ${\alpha}$ changes. In this paper, to solve this problem we suggest control algorithm to followed exactly value of ${\alpha}$ as 2-DOF parameter by using fuzzy algorithm . So, intelligence algorithm modeled by human knowledge, experience, teachability and judgment follow exact ${\alpha}$ value and it can compose the efficient 2-DOF PID controller to improve following performance, overshoot decrease.

• Journal of the Korean Society of Safety
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• v.35 no.3
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• pp.96-104
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• 2020

The numerical simulations were conducted to investigate the thermal-fluid phenomena occurred inside the experimental apparatus during a PCCS, used to remove heat released in accidents from a containment of light water nuclear power plant, operation. Numerical simulations of the flow and heat transfer caused by wall condensation inside the containment simulation vessel (CSV), which equipped with 18 vertical heat exchanger tubes, were conducted using the commercial computational fluid dynamics (CFD) software ANSYS-CFX. Shear stress transport (SST) and the wall condensation model were used for turbulence closure and wall condensation, respectively. The simulation using the actual size of the apparatus. However, rather than simulating the whole experimental apparatus in consideration of the experimental cases, calculation resources, and calculation time, the simulation model was prepared only in CSV. Selective simulation was conducted to verify the effects of non-condensable gas(NC gas) concentration, CSV internal pressure, and wall sub-cooling conditions. First, as a result of the internal flow of CSV, it was observed that downward flow due to condensation occurred surface of the vertical tube and upward flow occurred in the distant place. Natural convection occurred actively around the heat exchanger tube. Due to this rising and falling internal flow, natural circulation occurred actively around the heat exchanger tubes. Next, in order to check the performance of built-in condensation model using according to the non-condensable gas concentration, CSV internal flow and wall sub-cooling, the heat flux values were compared with the experimental results. On average, the results were underestimated with and error of about 25%. In addition, the influence of CSV internal pressure and wall sub-cooling was small, but when the condensate was highly generated due to the low non-condensable gas concentration, the error was large compared to the experimental values. This is considered to be due to the nature of the condensation model of the CFX code. However, in spite of the limitations of CFD, it is valid to use the built-in condensation model of CFD for PCCS performance prediction from a conservative perspective.

• Advances in Energy Research
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• v.5 no.1
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• pp.13-29
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• 2017

The roles of Na, Mn, W and silica, and the synergistic effects between each metal in the $MnNa_2WO_4/SiO_2$ catalyst have been investigated for oxidative coupling of methane (OCM). The crystallisation of amorphous silica during calcination at $900^{\circ}C$ was promoted primarily by Na, but Mn and W also facilitated this process. The interaction between Na and Mn tended to increase the extent of conversion of $Mn_3O_4$ to $Mn_2O_3$. The formation of $Na_2WO_4$ was dependent on the order in which Na and W were introduced to the catalyst. The impregnation of W before Na resulted in the formation of $Na_2WO_4$, but this did not occur when the impregnation order was reversed. $MnWO_4$ formed in all cases where Mn and W were introduced into the silica support, regardless of the impregnation order; however, the formation of $MnWO_4$ was inhibited in the presence of Na. Of the prepared samples in which a single metal oxide was introduced to silica, only $Mn/SiO_2$ showed OCM activity with significant oxygen conversion, thus demonstrating the important role that Mn plays in promoting oxygen transfer in the reaction. The impregnation order of W and Na is critical for catalyst performance. The active site, which involves a combination of Na-Si-W-O, can be formed in situ when distorted $WO_4^{2-}$ interacts with silica during the crystallisation process facilitated by Na. This can only occur if the impregnation of W occurs before Na addition, or if the two components are introduced simultaneously.

• KSBB Journal
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• v.30 no.6
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• pp.307-312
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• 2015

Transgenic rice cells using RAmy3D promoter can provide high productivity, and the production of recombinant protein is induced by sugar starvation. In this system, productivity was reduced during the scale-up processes. To ensure the influences of shear stress and oxygen transfer rate, working volume and mixing performances were investigated under various agitation speeds and working volumes. In addition, inoculation methods including suspended cells and filtered cells were compared. Working volumes and shaking speeds were 300, 450 mL and 80, 120 rpm, respectively. Hydrodynamic environment of each condition was measured numerically like mixing time and $k_La$. Good mixing performance and high shear stress were measured at high agitation speed and low volume. The highest level of hCTLA4Ig was 30.7 mg/L at 120 rpm, 300 mL. When conditioned medium was used for inoculation, increased cell growth was noticed during the day 0~4 and decreased slower than filtered cells. Compared with filtered cells, the maximum hCTLA4Ig level reached 37.8 mg/L at 120 rpm, 300 mL and lower protease activity level was observed. In conclusion mixing performance is critical factor for productivity and conditioned medium can have a positive effect on damaged cells caused by hydrodynamic shear stress.

• Korean Journal of Ecology and Environment
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• v.52 no.4
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• pp.394-402
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• 2019

The Agrobacterium tumefaciens mediated gene transfer is widely used to generate genetic transformation of plants and transient assay of temporal exogenous gene expression. Syringe infiltration system into tobacco (Nicotiana benthamiana) leaves is a powerful tool for transient expression of target protein to study protein localization, protein-protein binding and protein production. However, the protocol and technical information of transient gene expression, especially double strand RNA (dsRNA), in tobacco using Agrobacterium is not well known. Recently, dsRNA is crucial for insecticidal effect on destructive agronomic pest such as Corn rootworm. In this study, we investigated the factor influencing the dsRNA expression efficiency of syringe agro-infiltration in tobacco. To search the best combination for dsRNA transient expression in tobacco, applied two Agrobacterium cell lines and three plant vector systems. The efficiency of dsRNA expression has estimated by real-time PCR and digital PCR. As a result, pHellsgate12 vector constructs showed the most effective accumulation of dsRNA in the cell. These results indicated that the efficiency of dsRNA expression was depending on the kind of vector rather than Agrobacterium cells. In summary, the optimized combination of transient dsRNA expression system in tobacco might be useful to in vivo dsRNA expression for functional study and risk assessment of dsRNA.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.2
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• pp.77-85
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• 2010

Recently, As increasing cleanroom size, Stocker system is trending the large size and long distance for LCD material transfer system In order to rise a rate of production, the manufacturer are on the decrease of total tact time with Stocker system And the manufacturer are requested to high speed of next generation Stocker system Also manufacturers for the high oil prices through energy-saving conservation to minimize plant operating costs are required. Therefore, this paper propose optimal design of high efficiency Contactless Power Supply(CPS) system about high speed and energy savings of next generation Stocker system This paper proposes CPS system is applied in the long distance and straight section with Stocker system for energy savings. The test results of input!output characteristic and efficiency of CPS system on operating pattern of Stocker system were analyzed, and proved the applicability on commercial use.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.1
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• pp.110-116
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• 2020

As the management plan for domestic spent nuclear fuel is delayed, the storage of the operating nuclear power plant is approaching saturation, and the Kori 1 Unit that has reached its end of operation life is preparing for the dismantling plan. The first stage of dismantling is the transfer of spent nuclear fuel stored in storage at plants. The spent fuel management process leads to temporary storage, interim storage, reprocessing and permanent disposal. In this paper, the technical issues to be considered when transporting spent fuel in this process are summarized. The spent fuels are treated as high-level radioactive waste and strictly managed according to international regulations. A series of integrity tests are performed to demonstrate that spent fuel can be safely stored for decades in a dry environment before being transferred to an intermediate storage facility. The safety of spent fuel transport container must be demonstrated under normal transport conditions and virtual accident conditions. IAEA international standards are commonly applied to the design of transport containers, licensing regulations and transport regulations worldwide. In addition, each country operates a physical protection system to reduce and respond to the threat of radioactive terrorism.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.1
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• pp.1-10
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• 2018

Recently, interest in the development of alternative water resources has been increasing rapidly due to environmental pollution and depletion of water resources. In particular, seawater desalination has been attracting the most attention as alternative water resources. As seawater desalination consumes a large amount of energy due to high operating pressure, many researches have been conducted to improve energy efficiency such as energy recovery device (ERD). Consequently, this study aims to compare the energy efficiency of RO process according to ERD of isobaric type which is applied in scientific control pilot plant process of each $100m^3/day$ scale based on actual RO product water. As a result, it was confirmed that efficiency, mixing rate, and permeate conductivity were different depending on the size of the apparatus even though the same principle of the ERD was applied. It is believed that this is caused by the difference in cross-sectional area of the contacted portion for pressure transfer inside the ERD. Therefore, further study is needed to confirm the optimum conditions what is applicable to the actual process considering the correlation with other factors as well as the factors obtained from the previous experiments.

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1495-1501
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• 2012

In this study, an experiment was conducted on influent water with low concentrations of organic matter, such as river water or secondary treatment water of a sewage treatment plant, according to HRT changes by using aerobic biofilm. In the biofilm process, as the biofilm increases in thickness, the inner membrane can be low in oxygen transfer rate and become anaerobic conditions, while the detachment of biomass from biofilm occurs. To overcome these limitations in the detachment of microorganisms in biofilm, the yarn, which was made from poly propylene(PP), was weaved and manufactured into a tube. Then, a test was carried out by injecting air so that the interior of the biofilm could create aerobic conditions. The results of the experiment showed that the removal efficiency of $TCOD_{cr}$ reached 66.1~81.2% by HRT 2hr, and 50.9 ~61.8% after HRT 1 hr. The removal efficiency of $SCOD_{cr}$ was 45.9 to 55.1% by HRT 1hr, and 26.1% in HRT 0.5hr, showing the highest removal efficiency in HRT 1hr. The SS removal efficiency was at 81.8 to 94.6%, and the effluent SS concentration was very low, indicating less than 2.2 mg/L in all HRT's. As a result, the $SCOD_{cr}$ and $NH_4{^+}$-N that were removed per specific surface area and attached to microbial biofilm showed the highest efficiency in HRT 1hr with 8.37 $gSCOD_{cr}/m^2{\cdot}d$, 2.93 $gNH_4{^+}-N/m^2{\cdot}d$. From the result of reviewing the characteristics of biofilm growth, microorganisms were found to be attached, and increased by 36 days. Later, they decreased in number through detachment, but showed a tendency to increase again 41 days later due to microbial reproduction.