• Journal of Marine Bioscience and Biotechnology
• /
• v.8 no.1
• /
• pp.18-23
• /
• 2016

It is important to design photobioreactor by cheap material for economical microalgal biomass production. In this study, two types of marine photobioreactors (MPBR), made by either polyvinyl chloride (MPBR-PVC) or high density poly ethylene (MPBR-HDPE), are used and performance of these were compared. Tetraselmis sp. KCTC 12236BP is a green marine alga that isolated from Ganghwa Island, Korea, and the strain was used for marine cultivations using MPBR-PVC and MPBR-HDPE. The cultivations were performed three times in the spring season of 2012 using MPBR-PVC and of 2013 using MPBR-HDPE in the coastal area of Young Heung Island. As the results, MPBR-PVC shows higher biomass productivities than MPBR-HDPE, due to its high light transmittance. In the cultivations using MPBR-PVC, the average sea water temperature was $11.5^{\circ}C$ during the first experiment and $16.5^{\circ}C$ during the second and third experiments. Average light intensities during three times for experiments were 407.5, 268.1 and $273.0{\mu}{\cdot}E{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. The maximum fresh cell weight and average biomass productivity were $1.2g{\cdot}L^{-1}$ and $0.12g{\cdot}L^{-1}{\cdot}day^{-1}$. These results showed that Tetraselmis sp. KCTC12236BP were adapted well with the environmental conditions from ocean, and grow in the MPBR-PVC and MPBR-HDPE.

• Korean Journal of Medicinal Crop Science
• /
• v.5 no.2
• /
• pp.91-94
• /
• 1997

This experiment was carried out to investigate the effects of black P.E. film mulching by different sowing dates on the growth and yield of Achyranthes japonia NAKAI. Emergence rate and the growth increment were increased in black polyethylene (P.E.) film mulching of sowing date at April 1. Dried root yield was highest by 3,190kg/ha in black P.E. film mulching and earlist sowing at April 1 with 20% increase compared to that of non mulching at April 1 planting.

• Korean Journal of Weed Science
• /
• v.7 no.1
• /
• pp.52-57
• /
• 1987

To know the effects of weeding periods (weeding from 12 days, 28 days and 42 days after seeding to harvest, and weeding from seeding to 14 days, 28 days and 42 days after seeding) and growing conditions such as transparent polyethylene film mulch (P.E. mulch) and bare soil on growth and yield of peanuts, "Yeongho-Tangkong" was planted on May 10, 1984. Under P.E. mulch, the number of weeds was higher, but the weed dry weight was lower than in bare soil by the middle of July. Sixty days after seedings, the length of main stems in weedy check plots was longer, but shoot dry weight was lower compared to weed free plot. In the correlation coefficients between weed dry weight and the shoot dry weight of peanut on July 14, the growth retardation of peanuts due to weeds was showed earlier under P.E. mulch than in bare soil. Shoot dry weight, shelling ratio, number of seeds per pod, 100 pod weight, and seed yield were higher under P.E, mulch compared to bare soil. But weed dry weight, length of branches, number of pod bearing branches, number of pods per square meters, and pod yield were similar between P.E. mulch and bare soil. Shoot dry weight of peanuts, length of branches, number of pod bearing branches, number of pods per square meters, pod yield, 100 pod weight, 100 seed weight, and seed yield in weed free plots from 28 days after seeding to harvest (28 DAS-Harvest) were higher compared to weed free plots from 42 DAS-Harvest. However, in the weed free plot from seeding to 42 days after seeding seed yield was lower than that of the continuous weeding plot due to lower number of pod bearing branches and number of pods per square meters. When weed was not controlled at the later growth stages of peanuts, reduction in seed yield due to weeds was greater in bare soil than that under P.E. mulch.

• The Korean Journal of Mycology
• /
• v.18 no.3
• /
• pp.115-126
• /
• 1990

To establish basic techniques for protoplast fusion of Coriolus versicolor several factors affecting protoplast formation and regeneration were investigated. Protoplast isolation was at maximum with 2.5-day cultured mycelia of C. versicolor treated with the combination of two enzymes, Novozym 234 (10 mg/ml) and cellulase Onozuka R-10 (15 mg/ml), for 3-4.5 hours at $30^{\circ}C.$ As an osmotic stabilizer for stabilizing the protoplast, 0.6 M sucrose was the best for formation and regeneration of the protoplast from the mycelia of the fungus and the regeneration frequency was 3.48%. Protoplast fusion was made by a modified method of Peberdy using PEG (M.W. 4,000). The fusion frequency between two mutants of C. versicolor was 1.86% and the fusion products showed differences in growth rate and colony morphology.

• Journal of the Korea Concrete Institute
• /
• v.17 no.4 s.88
• /
• pp.499-504
• /
• 2005

Polymer concrete shows excellent mechanical properties and chemical resistance compared with conventional normal cement concrete. The polymer concrete Is drawing a strong interest as high-performance materials in the construction industry Resins using recycled PET offer the possibility of a lower source cost of materials for making useful polymer concrete products. Also the recycling of PET in polymer concrete would help solve some of the solid waste problems Posed by plastics and save energy. An objective of this paper is to estimate the damage of sulfuric acid, through investigating recycled PET polymer concrete, immersed at sulfuric acid solution for 84 days. As a result of testing, recycled PET PC, used $CaCO_3$ as filler, makes a problem of appearance and strength if they are exposed for long term at corrosion environment. On the other hand, recycled PET PC, used fly-ash as filler, had less effect on decrease in weight and strength. Recycled PET PC is excellent chemical resistance, resulting in the role of unsaturated polyester resin which consists of polymer chain structure accomplishes bond of aggregates and filler strongly. Also, recycled PET PC, used fly-ash as filler, is stronger resistance of sulfuric acid corrosion than $CaCO_3$, because it is composed of $SiO_2$ and very strong glassy crystal structure. Therefore, recycled PET PC, used fly-ash as filler, is available under corrosion circumstances like sewer pipe or waste disposal plant.

• Korean Chemical Engineering Research
• /
• v.45 no.3
• /
• pp.249-257
• /
• 2007

The periodic square wave (PSW) model was successfully applied to the optimal design of a batch-storage network. The network structure can cover any type of batch production, distribution and inventory system, including recycle streams. Here we extend the coverage of the PSW model to multitasking semi-continuous processes as well as pure continuous and batch processes. In previous solutions obtained using the PSW model, the feedstock composition and product yield were treated as known constants. This constraint is relaxed in the present work, which treats the feedstock composition and product yield as free variables to be optimized. This modification makes it possible to deal with the pooling problem commonly encountered in oil refinery processes. Despite the greater complexity that arises when the feedstock composition and product yield are free variables, the PSW model still gives analytic lot sizing equations. The ability of the proposed method to determine the optimal plant design is demonstrated through the example of a high density polyethylene (HDPE) plant. Based on the analytical optimality results, we propose a practical process optimality measure that can be used for any kind of process. This measure facilitates direct comparison of the performance of multiple processes, and hence is a useful tool for diagnosing the status of process systems. The result that the cost of a process is proportional to the square root of average flow rate is similar to the well-known six-tenths factor rule in plant design.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.3
• /
• pp.222-229
• /
• 2009

In this paper, we designed and fabricated the EM wave absorbers for preventing the reduction of the communication range when RFID Tag is approached to a metal plate. The EM wave absorber samples were fabricated with difference composition ratios of Amorphous metal powder and CPE, the absorption abilities of which were simulated by substituting different thicknesses of the EM wave absorbers. Then the EM wave absorbers are manufactured based on the simulated results. By using the EM wave absorbers, we have confirmed the improvement effect of RFID tag antenna and the increase of communication range of RFID system. As a result, it was cleary shown that the communication range of RFID system is improved by adopting the EM wave absorber with the composition ratio of Amorphous metal powder:CPE=80:20 wt.% and the thickness of 4 mm. Thus, it was confirmed that the proposed EM wave absorber can increase the communication range of RFID system from 0.8 m to 5.2 m in UHF band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.7
• /
• pp.671-677
• /
• 2013

In this paper, we propose a method of near-field analysis for vehicle LF antennas in order to estimate the accurate reading range of a smart key. The LF antenna consists of a ferrite core and a conducting wire which is coated with polyethylene for insulation, and it is mounted at the rear bumper frame of a commercial vehicle. The reading range of a smart key is measured at nine azimuthal directions distributed around the rear bumper, and then, the received power at each maximum reading range is measured by using a spectrum analyzer. The measurement shows that the maximum reading range exists between 1.38 m and 1.53 m, and the radiated power is between -83.6 dBmW and -75.0 dBmW. We further conducted EM simulation to estimate the reading range and the received power under the same condition that we applied for the measurement. The results demonstrate that an accurate reading range and received power can be achieved by simulation.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.42 no.9
• /
• pp.1518-1523
• /
• 2013

To estimate the shelf life of red cabbage sprouts (stored at 4 and $10^{\circ}C$), the numbers of total aerobic bacteria were determined during storage. Parameters for the Gompertz model were determined and the shelf life was predicted using a modified Gompertz equation. The estimated shelf lives of red cabbage sprouts packed with polyolefin film and polyamide/polyamide/polyethylene (PA/PA/PE) film at $4^{\circ}C$ were 49.4 and 52.3 h, respectively, whereas those of red cabbage sprouts packed with polyolefin film and PA/PA/PE film at $10^{\circ}C$ were 19.7 and 22.6, respectively. The shelf life prediction equation was appropriate, based on the statistical analysis of the accuracy factor, bias factor, and mean square error. On the other hand, for red cabbage sprouts treated with aqueous $ClO_2$/fumaric acid and UV-C then packed with polyolefin film or PA/PA/PE film, the shelf life was predicted to be longer than 168 h. These results suggest that the combined treatment of aqueous $ClO_2$/fumaric acid and UV-C can be useful for improving microbial safety and extending the shelf life of red cabbage sprouts during storage.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.13 no.6
• /
• pp.39-48
• /
• 2010

The purpose of this study was to analyze air temperature decreasing effects by shading and ventilation at micro-scale experiment plots, especially focused on the Wet Bulb Globe Temperature (WBGT) in outdoor spaces. To monitor the time-serial changes of Dry-bulb Temperature (DT), Globe Temperature (GT) and Relative Humidity (RH) in the wind blocking and shading conditions, Two hexahedral steel frames were established on the open grass field, the dimension of each frame was 1.5m(W)${\times}$1.5m(L)${\times}$1.5m(H). Four vertical side of one frame was covered by transparent polyethylene film to prevent wind passing through (Wind break plot; WP). The top side of the other frame was covered with shading curtain which intercept 95% of solar light and energy (Shading plot; SP). And, Another vertical steel frame without any treatment preventing ventilation and sunlight was set up, which represents natural conditions (Control plot; CP). The major findings were as follows; 1. The average globe temperature (GT) was highest at WP showing $50.94^{\circ}C$ and lowest at SP showing $34.58^{\circ}C$. The GT of natural condition (SP) was $42.31^{\circ}C$ locating the midst between WP and SP. The difference of GT of each plot was about $8-16^{\circ}C$, which means the ventilation and shading has significant effect on decreasing the temperature. 2. WP showed the highest average dry-bulb temperature (DT) of $38.41^{\circ}C$ which apparently differ from SP and CP showing $31.94^{\circ}C$ and $33.15^{\circ}C$ respectively. The DT of SP and CP were nearly the same. 3. The average relative humidity (RH) was lowest at WP showing 15.21%, but SP and CP had similar RH 28.79%, 28.02% respectively. 4. The average of calculated WBGT were the highest at the WP ($27.61^{\circ}C$) and the lowest at the SP ($23.64^{\circ}C$). The CP ($25.49^{\circ}C$) was in the middle of the others. As summery, compared with natural condition (CP), the wind blocking increased about $2.11^{\circ}C$ WBGT, but the shading decreased about $1.84^{\circ}C$ WBGT. So It can be apparently said that the open space with much shading trees, sheltering furnitures and well-delivered wind corridor can reduce useless and even harmful energy for human outdoor activity considerably in outdoor spaces.