• KSBB Journal
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• v.13 no.4
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• pp.418-423
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• 1998

Cellular transfections with cationic liposomes are widely empolyed for gene and oligonucleotide transfer in vitro because of their safety and ease of use. However, they still suffer from the low transfection efficiency comparing with viral vectors. Substantial effort shave been focused on increasing transfection efficiency by supplementing the liposome/DNA complexes(lipoplex) with various components. In this work, we tired three kinds of supplements, Poly-L-lysine(PLL), transferrin and a mixture of anionic lipids(PS/PE/PC), to study their effects on gene transfer yield and gene expression efficiency. PLL, a polycationic polymer, enhanced gene transfer yield by 3 times but the gene expression efficiency was increased only by 1.5 times. this result implies that PLL can enhance the transfection efficiency mainly by increasing the rate of outermembrane transport of lipoplex into the cells. On the other hand, transferrin which can facilitate the gene transfer via ligand-receptor interaction gave not only increased gene transfer yield but also enhanced gen expression efficiency by 2.8 times. Transferrin seems to contribute to the escape of plasmid from endosomes through ligand-receptor recycle mechanism. When the cells were treated with a mixture of anionic lipids for 3 hours before the transfection, gene transfer yield was slightly decreased but the gene expression efficiency was enhanced by 1.9 times. This is presumably due to the accelerated liposome-plasmid dissociation by the anionic lipids, and the increased delivery of plasmid to the nucleus. According to these results, it is clear that the supplementation to ameliorate transfection efficiency with cationic liposomes should be contrived in the direction of increasing delivery of plasmid.

• Current Photovoltaic Research
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• v.7 no.3
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• pp.61-64
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• 2019

In this study, we investigate organic-inorganic hybrid solar cells with a very simple three-layer structure (Al/n-Si/PEDOT:PSS). The performance of hybrid solar cells is optimized by controlling the sheet resistance and optical transmittance of the PEDOT:PSS layers. As the thickness of the PEDOT:PSS layer decreases, the optical absorption of the n-Si increases, which greatly improves the short-circuit current density ($J_{SC}$) of devices, but the increase in sheet resistance leads to a decrease in the open-circuit voltage ($V_{OC}$) and the fill factor (FF). The solar cell with the 180-nm thick PEDOT:PSS layer shows a highest efficiency of 8.45% ($V_{OC}$: 0.435 V, $J_{SC}$: $33.7mA/cm^2$, FF: 57.5%). Considering these results, it is expected that the optimizing process for the sheet resistance and transmittance of the PEDOT:PSS layer is essential for producing high-efficiency organic-inorganic hybrid solar cells and will serve as an important basis for achieving low-cost, high-efficiency solar cells.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.21-28
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• 2006

In this paper, the proposed full-bridge high frequency isolated zoo voltage and zero current switching phase shifted pulse width modulation(ZVZCS PS-PWM)DC-DC converter among fuel cell generation system consist of 1.2[kW] fuel cell of Nexa Power Module, full-bridge DC-DC converter to boost the fuel cell low voltage($28{\sim}43[%]$) to 380[VDC] and a single phase full-bridge inverter is implemented to produce AC output(220[VAC], 60[Hz]). A tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed full-bridge high frequency isolated ZVZCS PS-PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena. Besides the efficiency of $93{\sim}97[%]$ is obtained over the wide output voltage regulation ranges and load variations.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.281-288
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• 2011

Recently, researches that a variety of contaminants in water are removed by sonolysis technology with oxidation and pyrolysis process from cavitation were conducted. However, there are few studies for sonochemical treatment by a pilot-scale ultrasound system. This research focused on developing pilot-scale ultrasound systems, which could be an continuously effective treatment for a large volumes of contaminants, and demonstrating the feasibility of utilizing these systems to remove naphthalene from groundwater. V-120 type reactor was found to be 1.4~2.2 times higher effective than the normal type. A total of three different pilot scale's systems consisted of installing effluent and irrigation water in order to be a continuos system, including supplemental additives, and applying a V-120 type reactor and a external cooling cycle system. Naphthalene levels treated by three systems were lower than a recommended guideline of naphthalene for drinking water in EPA. Especially, the naphthalene removal efficiencies of PS1 and PS2 systems were over 97%. The pilot-scale continuous ultrasound clean-up system delivered over 84~95% naphthalene removal efficiency for treatment of 10~20 liter of groundwater. In addition, the ultrasound system could be successfully applied to the conditions of artificial and genuine groundwater contaminated with naphthalene.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.1
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• pp.24-34
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• 2020

Objective: The effects of Pleurotus ostreatus on the feed utilization of broad bean stalks (BBS), rape straw (RS), paddy straw (PS), and corn stalk (CS) was examined. Methods: The four roughages were co-cultured with Pleurotus ostreatus. The chemical composition; enzyme activities of laccase, carboxymethylcellulase (CMCase) and xylanase; carbohydrate and protein fractions (based on The Cornell Net Carbohydrate and Protein System [CNCPS]) were assessed at different days after inoculation (7, 14, 21, 28 d) and un-inoculated roughages (control, 0 d). The digestibility of nutrient components and the gas production of roughage with various incubation times were monitored at 0, 2, 4, 6, 9, 12, 24, 36, 48, 60, and 72 h using an in vitro ruminal fermentation method. Results: A higher CMCase activity (0.1039 U/mL) and earlier time to peak (14 d) were detected in Pleurotus ostreatus cultured with CS (p<0.05). Significantly, the incubation length-dependent responses of cumulative gas production were observed from 24 to 72 hours post fermentation (p<0.05), and these incubation length-dependent effects on cumulative gas production of PS and CS appeared earlier (24 h) for PS and CS than those (48 h) for BBS and RS (p<0.05). The fast-degradable carbohydrate (CA) content for all four roughages significantly increased over time (p<0.05). Nonetheless, increased degradation efficiency for CA treated with Pleurotus ostreatus was detected at both 21 and 28 days of incubation (p<0.05). With the exception of PS (p<0.05), there were no significant difference among the roughages (p>0.05) in slowly-degradable carbohydrate (CB2) at different incubation times (p<0.05). Conclusion: Assessment of the alterations in chemical composition, CNCPS system fractions, and the fermentation kinetics after biological pretreatment may yield a valuable database for evaluating the biological pretreatment of Pleurotus ostreatus in ruminant feed.

• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.569-579
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• 2019

In this study, the effect anti-oxidant, anti-inflammatory, and liver protective activity was investigated via quick ultrasonic disintegration of pine pollen using a probe sonicator (PS) followed by the extraction with water, 70% ethanol, and 100% ethanol. The anti-inflammatory effect was studied by measuring the production of nitric oxide (NO) and cytokine in RAW264.7 cells induced with lipopolysaccharides (LPS). The cell toxicity was also checked with an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the experiment was conducted using non-toxic $100{\mu}g/mL$. The NO inhibition rate was highest in the 70% ethanol PS group at $85.99{\pm}0.12%$. Also an excellent efficiency was obtained from the results of interlukin-1 beta ($IL-1{\beta}$) and tumor necrosis factor alpha ($TNF-{\alpha}$), which is related to inflammation-related cytokine, with the respective inhibition rates of 63 and 22%. To examine liver protective activity, HepG2 cells were treated with Taclin, and the generation of glutamic oxaloacetic transaminase (GOT) and lactate dehydrogenase (LDH) was measured in the culture solution. From GOT and LDH generation results, the inhibition rates in the 70% ethanol PS group were 28% and 13%, respectively, which was higher compared to that of using negative control group. Our results suggest that pine pollen extracted in 70% ethanol using PS may be used to develop food products that have anti-aging, anti-inflammatory, and liver protective effects.

• Korean Journal of Environmental Biology
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• v.19 no.1
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• pp.43-48
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• 2001

Chlorophyll fluorescence of needles of Korean fir (Abies koreana) plants and environmental factors of their natural habitat were investigated in order to obtain the information for environmental adaptation and conservation of Korean fir plants. The photochemical efficiency of photosystem II, Fv/Fm, of Korean fir needles was significantly low (0.19-0.36) in the winter, whereas it was high (0.8-0.86) in the summer. The Fv/Fm value of the winter was slightly higher at mid-day than at dawn, suggesting that mid-day environmental conditions of the winter were favorable on needles of Korean fir plants. In contrast, the mid-day Fv/Fm value of the summer maintained high (around 0.8). It indicates that mid-day environmental conditions of the summer did not induce photodamage, although it caused a slight decrease in the Fv/Fm values. The non-photochemical fluorescence quenching (NPQ) of Korean fir needles was very low (0-0.01) all through the day in the winter. However, it was high (0.76) at mid-day in the summer. These results suggest that Korean fir plants have a system for the protection of PS II from mid-day environmental stresses of the summer. In the winter, the Fv/Fm values were positively correlated with temperature, light intensity and relative humidity, although NPQ values showed no correlation with any of them. In the summer, the Fv/Fm values were positively correlated with relative humidity but negatively correlated with temperature and light intensity. These results indicate that increase of tempera-ture, light intensity and relative humidity lead to promotion of the photochemical efficiency in the winter and high temperature and light intensity may cause photoinhibition in the summer.

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.733-743
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• 2020

We estimated the carbon storage of coal mines reclaimed using Betula platyphylla (BP), Pinus koraiensis (PK), and Pinus spp. (PS, Pinus densiflora, Pinus rigida, and Pinus thunbergii). The carbon storage of tree biomass (TB), forest floor(FF), mineral soil (MS), and the total forest were quantified. Reclaimed sites were located in Gangwon-do, Gyeongsangbuk-do, and Jeollanam-do; reclamation was conducted at various times in each region. The carbon storage (ton C ha^-1) in FF (BP: 3.31±0.59, PK: 3.60±0.93, PS: 4.65±0.92), MS (BP: 28.62±2.86, PK: 22.26±5.72, PS: 19.95±3.90), and the total forest(BP: 54.81±7.22, PK: 47.29±8.97, PS: 45.50±6.31) were lower than that of natural forests (NF). The carbon storage in TB was lower in BP (22.57±6.18) compared to NF, while those in PK(21.17±8.76) and PS (20.80±6.40) were higher than in NF. While there were no significant differences in the carbon storage of TB, FF, and the total forest among tree species, results from MS showed a significant difference among species. TB and the total forest carbon storages in all sites increased after reclamation. Soil pH and cation exchange capacity values in BP and PS were lower than in NF. Amounts of labile carbon, available phosphate, and microbial biomass carbon in reclaimed sites were less than half of NF. There are a number of methods that could increase the reclamation efficiency. Applications of lime or organic fertilizers, as well as tillage operations, may improve soil properties in reclaimed coal mines. Additionally, pruning and thinning would increase tree growth thereby increasing carbon storage.

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.73-77
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• 2012

Operation of liquid crystal displays (LCDs) can be improved by monolithic integration of the pixel transistors with light emitting diodes (LEDs) on a single substrate. Conventional LCDs make use of filters to control the backlighting which reduces the overall efficiency. These LCDs also utilize LEDs in series which impose failure and they require high voltage for operation with a power factor correction. The screen of small hand-held devices can operate from moderate brightness. Therefore, III-V nanowires that are grown along with transistors over Silicon substrates can be utilized. Control of nanowire LEDs with nanowire transistors will significantly lower the cost, increase the efficiency, improve the manufacturing yield and simplify the structure of the small displays that are used in portable devices. The steps to grow nanowires on Silicon substrates are described. The vertical n-type and p-type nanowire transistors with surrounding gate structures are characterized. While biased at 0.5 V, nanowire transistors with minimum radius or channel width have an OFF current which is less than 1pA, an ON current more than 1 ${\mu}A$, a total delay less than 10 ps and a transconductance gain of more than 10 ${\mu}A/V$. The low power and fast switching characteristics of the nanowire transistor make them an ideal choice for the realization of future displays of portable devices with long battery lifetime.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.4
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• pp.41-48
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• 1986

To investigate the midwater trawl gear available for the Korean near sea trawlers, the authors carried out a field experiment on the attitude and the opening efficiency of the otter board with the Pusan 404 (160GT, 750ps), a training ship of National Fisheries University of Pusan. The experimental trawl gear was designed to be operable by the ship and the otter board was made of single iron plate with 12% camber ratio. The special-prepared potentiometric angle detector was used for determining the attitude, and the 50 KHz fish finder for the opening between the otter boards. The results obtained can be summarized as follows: 1. The angle of attack varied by moving the towing point on the towing plate of the otter board. It showed 33 to 36 degrees when the point was set at the outmost position, 25 to 31 degrees at the middle position and 19 to 30 degrees at the inmost position, with a decreasing tendency according to the increase of towing speed in each cases. 2. The heel of the otter board always occured inwards, increasing slightly according to the increase of towing speed. 3. The tilt of the otter board always occured outwards, increasing slightly according to the move of the towing point inwards, and decreasing slightly according to the increase of towing speed. 4. The opening between otter boards showed the largest value when the towing point was set at the outmost position.