• Journal of Power Electronics
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• v.15 no.4
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• pp.929-938
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• 2015

Maximum power point tracking (MPPT) and battery charging control are two important functions for a solar battery charger. The former improves utilization of the available solar energy, while the latter ensures a prolonged battery life. Nevertheless, complete implementation of both functions can be complex and costly, especially for low voltage application such as standalone street lamps. In this paper, the operation of a solar battery charger for standalone street light systems is investigated. Using only one voltage sensor, the solar charger is able to operate in both MPPT and constant voltage (CV) charging mode, hence providing high performance at a low cost. Using a lab prototype and a solar simulator, the operation of the charger system is demonstrated and its performance under varying irradiance is validated.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.9
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• pp.964-970
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• 2012

Various eco-design tools have been developed which can be classified into quantitative, semi-quantitative, and qualitative tools. Practitioners are reluctant to utilize quantitative tools in light of their time-demanding nature. Among the qualitative tools, checklists are simple tools that allow a quick and effective evaluation and consideration of environmental impacts over the entire life cycle of a product. A profound and better understanding of eco-design checklists is needed so that practitioners can apply them appropriately to their product development context. Various types of eco-design checklists are analyzed in the present study based on their attributes and classified in a structured way for their efficient utilization in product development contexts.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.5
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• pp.483-487
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• 1991

The utilization of ozone as a disinfectant for removing poultry meat microorganisms and then cleaning the poultry rinse water was investigated. When microbial suspensions were treated with ozone at 2, 500ppm/min for 40min, microorganisms were not detectable perfectly. The bacteriocidal effect of ozone by temperature was enhanced greater at 7$^{\circ}C$ than $25^{\circ}C$. All poultry meat microorganisms were killed by ozone treatment at 1, 530ppm for 50min. The pathogenic bacteria such as Salmonella sp. were more vulnerable and not detected by ozone treatment for 20min. Ozonation of the suspension for 20min and 50min increased light transmission at 500nm to 58% and 145%, respectively. The order of COD removal was ozone treatment(21%), coagulant((Al)2SO4) treatment(41%), ozone treatment after coagulant treatment(54%).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.4
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• pp.326-331
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• 2023

The utilization of scanning transmission electron microscopy (STEM) in conjunction with cathodoluminescence (CL) has emerged as a valuable tool for the investigation of material optical properties. In recent years, this technique has facilitated significant advancements in the fields of plasmonics and quantum emitters by surpassing prior technical restrictions. The review commences by providing an outline of the diverse STEM-CL operating modes and technical aspects of the instrumentation. The review explains the fundamental physics of light production under electron beam irradiation and the physical basis for interpreting STEM-CL experiments for different types of excitations. Additionally, the review compares STEM-CL to other related techniques such as scanning electron microscope CL, photoluminescence, and electron energy-loss spectroscopy.

• Analytical Science and Technology
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• v.36 no.6
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• pp.259-266
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• 2023

The demand for rare-earth elements (REEs) is increasing owing to their significance as prominent materials in electronics, high-tech industries, geological research, nuclear forensics, and environmental monitoring. In general, the utilization of REEs in various applications requires the use of chromatographic techniques to separate individual elements. However, REEs have similar physicochemical properties, which makes them difficult to separate. Recently, several studies have examined the separation of REEs using LN resin as the stationary phase and aqueous nitric acid and hydrochloric acid solutions as eluents. Using this method, light REEs have been separated using dilute acid solutions as the eluent, whereas heavy REEs are separated using solutions with high acid concentrations. To increase the separation resolution between different REEs, either the column length or resin size is changed. In addition, the suggested methods are implemented to decrease the analysis time. This review presents technical information on the chromatographic separation of REEs using the LN resin and discusses the optimal experimental conditions.

• Journal of Microbiology and Biotechnology
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• v.26 no.6
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• pp.989-998
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• 2016

Acidic endo-polygalacturonases are the major part of pectinase preparations and extensively applied in the clarification of fruits juice, vegetables extracts, and wines. However, most of the reported fungal endo-polygalacturonases are active and stable under narrow pH range and low temperatures. In this study, an acidic endo-polygalacturonase (EPG4) was purified and characterized from a mutant strain of Penicillium oxalicum. The N-terminal amino acid sequence of EPG4 (ATTCTFSGSNGAASASKSQT) was different from those of reported endo-polygalacturonases. EPG4 displayed optimal pH and temperature at 5.0 and 60-70℃ towards polygalacturonic acid (PGA), respectively, and was notably stable at pH 2.2-7.0. When tested against pectins, EPG4 showed enzyme activity over a broad acidic pH range (>15.0% activity at pH 2.2-6.0 towards citrus pectin; and >26.6% activity at pH 2.2-7.0 towards apple pectin). The K_m and V_max values were determined as 1.27 mg/ml and 5,504.6 U/mg, respectively. The enzyme hydrolyzed PGA in endo-manner, releasing oligo-galacturonates from PGA, as determined by TLC. Addition of EPG4 (3.6 U/ml) significantly reduced the viscosity (by 42.4%) and increased the light transmittance (by 29.5%) of the papaya pulp, and increased the recovery (by 24.4%) of the papaya extraction. All of these properties make the enzyme a potential application in the beverage industry.

• 한국해양학회지
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• v.27 no.3
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• pp.237-246
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• 1992

In order to examine controlling factors on primary productivity and assimilation Number of phytoplankton, chlorophyll-a concentrations, light intensity, temperature, salinity and transparency were measured in the Kyonggi Bay and in the mid0eastern coast of Yellow Sea from March 1989 to October 1990. Chlorophyll-a concentration of phytoplankton ranged from 0.91 to 4.30 ug/; in the Kyonggi Bay, and from 0.78 to 4.97 ug/l in the mideastern coast of Yellow Sea. Daily averaged primary productivities and annual primary productivities of phytoplankton ranged from 37.23 to 1104.44 (averaged 361.54) mgC/m$^2$/day, 131.96hC/m$^2$/yr in the mid0eastern coast of Yellow Sea, respectively. Assimilation Number of phytoplankton ranged from 1.47 to 28.28 mgC/mg chl-a/hr in the Kyonggi Bay, and of phytoplankton in the Kyonggi Bay was higher than that of the mid0eastern coast of Yellow Sea. Light utilization efficiencies (a) in the P-I curve ranged from 0.03 to 0.93 [mgC/mg chl-a/hr]/[ue/m$^2$/sec]in the Kyonggi Bay, and from 0.01 to 0.62 [mgC/mg chl-a/hr]/[ue/m$^2$/sec] in the mid-eastern coast of Yellow Sea. Their results indicated that phytoplankton in the Kyonggi Bay utilized light more efficiently than those of the mid0eastern coast of Yellow Sea. The average values of I/SUB k/ were 48.15 ue/m$^2$/sec in the Kyonggi Bay, and 120.37 uE/m$^2$/sec in the mid-eastern coast of yellow Sea. It means the phytoplankton populations in the Kyonggi Bay seem to be adapted to lower light intensity than those of the mid-eastern coast of Yellow sea.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.4
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• pp.561-566
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• 2008

Two experiments were conducted to evaluate nutritive value of cell mass from lysine production (CMLP) as a protein supplement for ruminants. In each experiment, animals were fed a diet containing 40% of forages and 60% of concentrates, mainly composed of rice straw and ground corn, respectively, to meet the maintenance requirements, and the diets were formulated to supply equal amounts of energy and nitrogen among treatments. In order to investigate the effect of CMLP on ruminal fermentation (Experiment 1), three Korean native goats weighing $26.1{\pm}1.4kg$ were allotted into individual cages with a $3{\times}3$ Latin square design. Each animal was fed one of three protein sources (CMLP, soybean meal (SBM), and urea). Rumen pH, bacterial and fungal counts, volatile fatty acid concentrations and acetate to propionate ratio were not significantly different among treatments. Concentration of propionate, however, was higher in SBM treatment (14.1 mM) than in CMLP (8.7 mM) or urea (9.3 mM) treatments. There was significantly more branch-chain volatile fatty acid production in CMLP (1.9 mM) and SBM (1.8 mM) treatments than in urea (1.3 mM) treatment. The number of protozoa was the highest in urea treatment, followed by CMLP and SBM treatment with significant differences. A metabolic trial (Experiment 2) was conducted to measure in vivo nutrient digestibility and nitrogen retention in Korean native goats fed CMLP and SBM. Two heavy ($35.0{\pm}1.2kg$) and two light ($25.0{\pm}0.9kg$) Korean native goats, caged individually, were used in this experiment. A heavy and a light animal were paired and supplemented with either CMLP or SBM. The animals fed CMLP showed a trend of lower total tract digestibility in all the nutrients measured; however, there was no statistical significance except for digestibility of ether extract. Nitrogen digestibility of CMLP was estimated to be about 7% units lower than that of SBM. There was a tendency for lower nitrogen retention in CMLP treatment (35.9%) compared to SBM treatment (42.3%). In summary, CMLP can be a good protein source for ruminant animals from nutritional and economic perspectives and may replace some, if not all, of SBM in a diet without losing nitrogen utilization efficiency. Further research is warranted for investigating the effect of CMLP fed with easily fermentable forage and the effective level of CMLP for replacing SBM.

• Journal of the Korean Wood Science and Technology
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• v.39 no.1
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• pp.41-52
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• 2011

This study was carried out to investigate the effect of energy saving and sound insulation of building materials mixed with charcoal. To investigate the functionality of building based on the difference of construction materials, three different experimental buildings were constructed. They were buildings built with the conventional construction materials (A), the charcoal construction materials (B), and the charcoal-sericite construction materials (C). The study showed that energy consumption could be reduced approximately 9.5% and 14.5% by replacing A with B and C, respectively. Especially, it is revealed that the lower outdoor temperature was, the higher energy saving effect was. Also, after shutoff the boiler switch the decrease rate of room temperature of the one using B was lower than those of others using A and C so that the room temperature at the building using B was higher by $3.5{\sim}4.2^{\circ}C$ in the 1 meter air above the ground and by $4.4{\sim}5.4^{\circ}C$ on the floor surface after 12 hours passed. In the building noise test the heavy-and light-weight impact sound of the plate, represented by criterion of noise between floors in multi-story building, tended to decrease in the test sample containing charcoal.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.518-525
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• 2010

Infrared (IR) thermography which is the technique for detecting invisible infrared light emitted by objects due to their surface thermal condition and for producing an image of the light has been applied in various field without damaging the objects. It also could be used indirectly to examine the inside of an object. In this study, insulation property of wooden house in Korea Forest Research Institute (KFRI) was evaluated with according to "Thermal performance of building - Quantitative detection of thermal irregularities in building envelopes - infrared method (KS F 2829)". This method uses "Temperature Difference Ratio (TDR)" between outdoor wall surface and indoor wall surface of wooden building for evaluating its thermal performance. The thermal performance of a room on the 2nd floor of the wooden house was focused in this study and IR thermography on the indoor and outdoor surface of the house was captured by IR camera. Heat loss from the corner and the window of the wooden house as well as wall of the house was quantitatively evaluated and the invisible heat loss in the wall was detected. It is expected that the results from this study could contribute to improve the wooden building energy efficiency.