• Journal of Life Science
• /
• v.26 no.12
• /
• pp.1477-1486
• /
• 2016

Lactulose (4-O-${\beta}$-D-galactopyranosyl-D-fructose) is a non-digestible synthetic ketose disaccharide which can used in food and pharmaceutical fields due to its useful functions for encephalopathy, chronic constipation, hyperammonemia, etc. Therefore, the lactulose is regarded as one of the most important disaccharides and have been concentrated much interesting as an attractive functional material in the current industry. From this reason, the research related on the production of lactulose has been carried out various academic and industrial research groups. To produce lactulose, two main methods, chemical production and enzymatic production have been used. Commercially lactulose produced by alkaline isomerization of lactose as chemical production method but it has many disadvantages such as rapid lactulose degradation, purification, and waste management. From these reasons, lactulose produced by enzymatic method which solves these problems has been suggested as a proper method for lactulose production. Two different enzymatic methods have been reported as methods for lactulose production. Lactulose can be obtained through hydrolysis and transfer reaction catalyzed by a ${\beta}$-galactosidase which requires fructose as co-substrate and exhibits a low conversion. Alternatively, lactulose can be produced by direct isomerization of lactose to lactulose catalyzed by cellobiose 2-epimerase which requires lactose as a single substrate and achieves a high lactulose yield. This review summarizes the current state of lactulose production by chemical and biological methods.

• Journal of IKEEE
• /
• v.13 no.2
• /
• pp.118-125
• /
• 2009

With recent advancement of high-speed, multi-gigabit data transmission capabilities, transmitters usually send data without clock signals for reduction of hardware complexity, power consumption, and cost. Therefore clock and data recovery circuits(CDR) become important to recover the clock and data signals and have been widely studied. This paper presents the design of 10Gbps CDR in 0.18$\mu$m CMOS process. A quarter-rate bang-bang phase detector is designed to reduce the power and circuit complexity, and a 4-stage LC-type VCO is used to improve the jitter characteristics. Simulation results show that the designed CDR consumes 80mW from a 1.8V supply, and exhibits a peak-to-peak jitter of 2.2ps in the recovered clock. The chip layout area excluding pads is 1.26mm$\times$1.05mm.

• The Korean Journal of Pesticide Science
• /
• v.10 no.2
• /
• pp.131-137
• /
• 2006

This experiment was conducted to select prominent microorganisms with a good insecticidal activity among the ten species, which isolated from soil at the near of Chung-buk, Chung-nam, and Gang-won provinces and made protein crystal endotoxin. As a result, GB-413 strain was finally selected, which showed the high insecticidal activity against susceptible diamondback moth (Plutella xylostella), beet army worm (Spodoptera exigua) and tobacco cutworm (Spodoptera litura) as well as resistant diamondback moth strains. By modifying the cultivation process f.g. lowing the glucose concentration at early cultivation stage and adding the carbon after inducing the spores, the percentage of making spore as well as the number of active spore were increased and the time for cultivation and spore forming was reduced without a reduction of insecticidal activity. These results were not only applied successfully for the optimized cultivation process for a fermentation tank containing five tons capacity, but also improved the possibility of mass cultivation for commercial production.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.6
• /
• pp.577-582
• /
• 2013

AZO (aluminum-doped zinc oxide) is one of the best candidate materials to replace ITO (indium tin oxide) for TCOs (transparent conductive oxides) used in flat panel displays, organic light-emitting diodes (OLEDs), and organic solar cells (OSCs). In the present study, to apply an AZO thin film to the transparent electrode of an organic solar cell, a low-temperature selective atomic layer deposition (ALD) process was adopted to deposit an AZO thin film on a flexible poly-ethylene-naphthalate (PEN) substrate. The reactive gases for the ALD process were di-ethyl-zinc (DEZ) and tri-methyl-aluminum (TMA) as precursors and H2O as an oxidant. The structural, electrical, and optical characteristics of the AZO thin film were evaluated. From the measured results of the electrical and optical characteristics of the AZO thin films deposited on the PEN substrates by ALD, it was shown that the AZO thin film appeared to be comparable to a commercially used ITO thin film, which confirmed the feasibility of AZO as a TCO for flexible organic solar cells in the near future.

• Journal of Korean Society on Water Environment
• /
• v.21 no.1
• /
• pp.66-72
• /
• 2005

Effect of the pH, molar ratio of Cu(II)/EDTA, concentration of Cu(II)-EDTA and ionic strength on the photocatalytic oxidation(PCO) of Cu(II)-EDTA in solar light was studied in this work. Experimental results in this work were compared with previous results obtained with UV-lamp. In the kinetics, Cu(II)-EDTA decomposition was favorable below neutral pH. The removal of Cu(II) and DOC was favorable as $TiO_2$ dosage increased. The initial rate for the decomplexation of Cu(II)-EDTA linearly increased as the concentration of Cu(II)-EDTA increased. The removal of Cu(II) and DOC was not much affected by variation of ionic strength with $NaClO_4$ as a background ion while much reduction was observed in the presence of background ions having higher formal charges. The removal trend of Cu(II) and DOC with variation of ionic strength and concentration of Cu(II)-EDTA in solar light was similar with that in UV light. Variation of the molar ratio of Cu(II)/EDTA showed a negligible effect on the removal of both Cu(II) and DOC. However, removal of both Cu(II) and DOC was two-times greater than that previous results obtained with UV light.

• Membrane Journal
• /
• v.24 no.2
• /
• pp.123-135
• /
• 2014

The effects of pH, saturated oxygen, and back-flushing media were investigated in hybrid process of tubular ceramic microfiltration and $TiO_2$ photocatalyst-loaded PES (polyethersulfone) beads for advanced drinking water treatment, and compared results of water, nitrogen, or oxygen back-flushing in the viewpoints of membrane fouling resistance ($R_f$), permeate flux (J) and total treated water ($V_T$). $R_f$ decreased, and J and $V_T$ increased as decreasing pH. Turbidity treatment efficiencies were similar at water or nitrogen back-flushing independent of pH, but DOM (dissolved organic matter) treatment efficiency did not have a trend at water back-flushing. $R_f$ at NBF (no back-flushing) with SO (saturated oxygen) was the lower than that at NBF without SO. Also, the DOM treatment efficiency at NBF with SO was the lower than that at NBF without SO. It happened because OH radicals produced by reaction of SO and photocatalyst could dilute with water inside the module. The DOM treatment efficiency of gas back-flushing showed the larger than that of water back-flushing at back-flushig period 10 min. It proved that the adsorption or photo-oxidation of PES beads could be activated by the more effective bead-cleaning of gas back-flushing than water back-flushing.

• Journal of the Microelectronics and Packaging Society
• /
• v.27 no.4
• /
• pp.83-89
• /
• 2020

For the past few decades, as part of efforts to protect the environment where fossil fuels, which have been a key energy resource for mankind, are becoming increasingly depleted and pollution due to industrial development, ecofriendly secondary batteries, hydrogen generating energy devices, energy storage systems, and many other new energy technologies are being developed. Among them, the lithium-ion battery (LIB) is considered to be a next-generation energy device suitable for application as a large-capacity battery and capable of industrial application due to its high energy density and long lifespan. However, considering the growing battery market such as eco-friendly electric vehicles and drones, it is expected that a large amount of battery waste will spill out from some point due to the end of life. In order to prepare for this situation, development of a process for recovering lithium and various valuable metals from waste batteries is required, and at the same time, a plan to recycle them is socially required. In this study, we introduce a nanoscale pattern transfer printing (NTP) process of Li2CO3, a representative anode material for lithium ion batteries, one of the strategic materials for recycling waste batteries. First, Li2CO3 powder was formed by pressing in a vacuum, and a 3-inch sputter target for very pure Li2CO3 thin film deposition was successfully produced through high-temperature sintering. The target was mounted on a sputtering device, and a well-ordered Li2CO3 line pattern with a width of 250 nm was successfully obtained on the Si substrate using the NTP process. In addition, based on the nTP method, the periodic Li2CO3 line patterns were formed on the surfaces of metal, glass, flexible polymer substrates, and even curved goggles. These results are expected to be applied to the thin films of various functional materials used in battery devices in the future, and is also expected to be particularly helpful in improving the performance of lithium-ion battery devices on various substrates.

• Membrane Journal
• /
• v.17 no.2
• /
• pp.99-111
• /
• 2007

It is impossible to remove toxic organic substances that are recognized as a cancer caused suspicious element in drinking water using the conventional water purification method. This study introduces groundwater into a reaction chamber as an effective amount of water to process this water using a mixed method of AOP oxidation and M/F membrane and purifies it as a desirable level by artificially mixing such toxic substances in order to effectively process the water. Based on this fact, this study configures an optimal operation condition. The VOCs existed in toxic substances was investigated as a term of phenol and toluene, and agricultural chemicals were also investigated as a term of parathion, diazinon and carbaryl. The experiment applied in this study was performed using a single and composite soolution. In the operation condition applied to fully dissolve and remove such substances, the amount of $H_2O_2$ injected in the process was 150 mL of a fixed quantity, the value of pH was configured as $5.5{\sim}6.0$, the temperature was controlled as a range of $12{\sim}16^{\circ}C$, the dissolved amount of ozone was applied more than 5.0 mg/L, the reaction time was determined as an optimal condition, such as $30{\sim}40$ minutes, and the segregation membrane in the same reactor was determined for acquire water drinking of large quantity using a pore size of $0.45{\mu}m$ M/F membrane.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.3 no.1
• /
• pp.91-98
• /
• 1993

This study was carried out to investigate characteristic of vinyl chloride emissioned from poly vinyl chloride extrusion process and to evaluate the efficiency of local exhaust ventilation system. Before local ventilation facility was constructed in poly vinyl chloride extrusion process, the average worker exposure to vinyl chloride was 3.15 ppm, which exceeded Threshold Limit Value of American Conference of Gorvernmental Industrial Hygienists (ACGIH-TLV), 1 ppm. lt is possible that vinyl chloride residues in the poly vinyl chloride resin was released or degased due to extrusion heat. The larger the width of vinyl tube become, the higher worker exposure to vinyl chloride was. It is estimated that vinyl chloride from vinyl chloride resin increased as amount of poly vinyl chloride resin extruded in the extrusion process increased. Canopy hood was an appropriate type for poly vinyl chloride resin extrusion process. This local exhaust ventilation has fan static pressure of 7.65 inch wg($190mmH_2O$, total volumetric flowlate of 4,796 CFM ($135.8m^3$/min) and fan power requirement of 12 hp (8.952 Kw). After this local exhaust ventilation was constructed there, the average concentration of worker exposure to vinyl chloride was reduced to be 0.46 ppm, which was below the Threshold Limit Value, 1 ppm. Also, the removal efficiency rate of vinyl chloride attained by local exhaust ventilation was 85.3%. It was a statistically significant (p<0.01).

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.4
• /
• pp.336-341
• /
• 2008

Recently, research on a flat panel display(FPD) has focused on organic light-emitting display(OLED) which has wide angle of view, high contrast ratio and low power consumption. ITO(Indium-Tin-Oxide) films are the most widely used material as a transparent electrode of OLED and also in many other display devices like LCD or PDP. The performance and efficiency of OLED is related to the surface condition of ITO coated glass substrate. The typical surface defect of glass substrate is measured for electric characteristics and physical condition for transmittance and roughness. Since ITO coated glass substrate can be destroyed for inspection about surface roughness, sheet resistance, film thickness and transmittance, precise fabrication condition should be made based on the estimated relationship. In this paper, ITO films were prepared on the commercial glass substrate by the Ion-Plating method changing the partial pressure of gas(Ar, 02) and the chamber temperature between $200^{\circ}C$ and $300^{\circ}C$. The characteristics of films were examined by the 4-point probe, supersonic thickness measurement, transmittance measurement and AFM. We estimated the relationship between processing parameters(Ar gas, O2 gas, Temperature) and properties of ITO films (Sheet Resistance, Film Thickness, Transmittance, Surface Roughness).