• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.5
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• pp.278-284
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• 2014

Water temperature due to climate change can be estimated using the air temperature because the air and water temperatures are closely related and the water temperatures have been widely used as the indicators of the environmental and ecological changes. It is highly necessary to estimate the frequency distribution of the air and water temperatures, for the climate change derives the change of the coastal water temperatures. In this study, the distribution function of the air temperatures is estimated by using the long-term coastal air temperature data sets in Korea. The candidate distribution function is the bi-modal distribution function used in the previous studies, such as Cho et al.(2003) on tidal elevation data and Jeong et al.(2013) on the coastal water temperature data. The parameters of the function are optimally estimated based on the least square method. It shows that the optimal parameters are highly correlated to the basic statistical informations, such as mean, standard deviation, and skewness coefficient. The RMS error of the parameter estimation using statistical information ranges is about 5 %. In addition, the bimodal distribution fits good to the overall frequency pattern of the air temperature. However, it can be regarded as the limitations that the distribution shows some mismatch with the rapid decreasing pattern in the high-temperature region and the some small peaks.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.96-101
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• 2015

In the previous study, we investigated the physical properties of new organic fillers made from major agricultural byproducts, including rice husks, peanut husks and garlic stems, and we estimated that rice husk was the best candidate for use as new organic fillers in paperboard. In this study, an organic filler prototype was produced with rice husk and the mill trials were carried out in a white liner chipboard (duplexboard) mill. The rice husk organic filler was added to the middle ply of SC $350g/m^2$ to determine the optimal conditions for the manufacture of rice husk organic fillers. The mill trials were performed three times and the bulk improvement and drying energy reduction were measured to identify the functionality of the rice husk organic filler compared to that of the commercial wood powder. In the first mill trial, the test failed because the surface roughness of the duplexboard had deteriorated after the rice husk organic filler was added to the OCC stock. As all of the particles remaining on the 60 mesh sieves were removed and the particle size was decreased by increasing the length of the grinding process, the surface roughness of the duplexboard did not be deteriorated in the second mill trial. However, the bulk improvement and drying energy reduction were not observed. In the final mill trial, as the particle size of the rice husk organic filler was controlled by increasing the portion of particles passing through the 60 mesh sieves and remaining 100 mesh sieves, higher bulk improvement and drying energy reduction were acquired compared to the commercial wood powder.

• Information Systems Review
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• v.13 no.3
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• pp.123-139
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• 2011

This paper researches the value of domestic telecommunication bundle products. Customers evaluate each telecommunication products differently according to their attributes. The attributes affecting the customer value of telecommunication bundling can be categorized in 3 ones as follows; corporate image, service feature, and service price. Also authors analyze the difference of importancy that customers consider when they evaluate each products, and propose the optimal scenario for bundling. In conclusion, other two companies A, C excluding B should invest more resources into the portion that strengthen the attributes of company image, and service feature to upgrade their 'corporate image', and 'service feature'. According to 6-scenarios analysis on the bundle products, the QPS expansion of company A was the most advantageous position, but if companies B, C expand DPS made use of their strengths, they can prevent from decreasing additivity rapidly with sequential scenario. The above results show that one company may have equable power in each area, but if another company having strengths in special areas makes up for its weakness and differentiates gradually it can contribute to strengthen its competitiveness. This contributed much more theoretical and practical than the existing researches. Supposing that additivity index evaluated by consumers can be changed by efforts of companies, this scenario planning is the result of study showing that the investment and publicity of each company have to be considered as its characteristic of each product at the same time.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.1
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• pp.19-26
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• 2010

A PEMFC(proton exchange membrane fuel cell) is a good candidate for residential power generation to be coped with the shortage of fossil fuel and green house gas emission. The attractive benefit of the PEMFC is to produce electric power as well as hot water for home usage. The thermal management of PEMFC for RPG is to utilize the heat of PEMFC so that the PEMFC can be operated at its optimal efficiency. In this study, thermal management system of PEMFC stack is modeled to understand the dynamic response during load change. The thermal management system of PEMFC for RPGFC is composed of two cooling circuits, one for controling the fuel cell temperature and the other for heating up the water for home usage. The different operating strategy is applied for each cooling circuit considering the duty of those two circuits. Even though the capacity of PEMFC system (1kW) is enough to supply hot domestic water for residence, heat-up of reservior takes some hours. Therefore, in this study, time schedule of the simulation reflects the heat-up process. Dynamic responses and operating strategies of the PEMFC system are investigated during load changes.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.235-235
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• 2003

The development of a buffer layer is an important issue for the second -generation wire, YBCO coated metal wire. The buffer layer demands not only on the prohibition of the reaction between YBCO and metal substrate, but also the proper lattice match and conductivity for high critical current density (Jc) of YBCO superconductor, In order to satisfy these demands, we suggested CaRuO3 as a useful candidate having that the lattice mismatches with Ni (200) and with YBCO are 8.2% and 8.0%, respectively. The CaRuO3 thin films were deposited on Ni substrates using various methods, such as e-beam evaporation and DC and RF magnetron sputtering. These films were investigated using SEM, XRD, pole-figure and AES. In e-beam evaporation, the deposition temperature of CaRuO3 was the most important since both hi-axial texturing and NiO formation between Ni and CaRuO3 depended on it. Also, the oxygen flow rate had i[n effect on the growth of CaRuO3 on Ni substrates. The optimal conditions of crystal growth and film uniformity were 400$^{\circ}C$, 50 ㎃ and 7 ㎸ when oxygen flow rate was 70∼100sccm In RF magnetron sputtering, CaRuO3 was deposited on Ni substrates with various conditions and annealing temperatures. As a result, the conductivity of CaRuO3 thin films was dependent on CaRuO3 layer thickness and fabrication temperature. We suggested the multi-step deposition, such as two-step deposition with different temperature, to prohibit the NiO formation and to control the hi-axial texture.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.4
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• pp.266-273
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• 2015

In this paper, annual wind data in 2014 at six locations(Seosudo, Gadaeam, Sibidongpa, Galmaeyeo, Haesuseo, Jigwido) are collected and analyzed in order to review optimal candidate site for offshore wind farm in the Western Seas of Korea. Observed wind data is fitted to Rayleigh and Weibull distribution and annual energy production is estimated according to wind frequency. GWE-3kH(3 kW-class) and GWE-10KU (10 kW-class) turbine are selected as wind turbine. Also, power curve are used to calculate wind energy potential. As a result, annual mean wind speed at six locations(Seosudo, Gadaeam, Sibidongpa, Galmaeyeo, Haesuseo, Jigwido) were calculated about 4.60, 4.5, 5.00, 5.13, 5.51, 5.90 m/s, respectively. In addition, annual energy production were estimated at 10,622.752, 11,313.05, 13,509.41, 14,899.55, 17,106.13, 19,660.85 kWh. Generally, annual mean energy density were between poor and marginal class and capacity factor at Jigwido was calculated at 22.44%. Its value is higher than the others.

• Journal of Applied Biological Chemistry
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• v.56 no.4
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• pp.241-244
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• 2013

Nitrate is one of the major nutrients in plants, and nitrate fertilizer often overused for the high yields of crops. Nitrate deposit in soil became one of the major reasons causing salt stress. Specially, salt stress is a serious problem in the soils of plastic film or glass houses. In this study, six microorganisms have been isolated from the wet soils near the disposals of livestock farms and their nitrate uptake activities were investigated. These bacteria were able to remove nitrate as high as 1,000-3,000 ppm (10-50 mM). The strain PCE3 showed the highest nitrate uptake activity and it removed more than 3,700 ppm. In order to identify these bacteria, genes of 16S rRNA were sequenced and analyzed. Phylogenetic trees were constructed with the neighbor-joining methods. Among these bacteria, strain PCE3 was identified as Bacillus species. When the growth and nitrate uptake activities were measured, both were maximal at $37^{\circ}C$ and optimal pH was pH 7-9. Bacillus sp. PCE3 removed nitrate up to 40-60 mM (2,500-3,700 ppm) depending on the nitrate concentration in media. Therefore, Bacillus sp. PCE3 can be a good candidate for the microbial remediation of nitrate-deposited soils in glass and plastic film houses.

• Science of Emotion and Sensibility
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• v.21 no.2
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• pp.137-144
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• 2018

The study figured out the operational conditions of a two-way movement actuator made of one-way shape memory alloy (OWSMA) for versatile ventilation intelligent garments. To develop a low-power actuator that consumes energy only when a garment changes its form such as opening and closing, multiple channels of OWSMA were used, and optimum diameter of the wires was examined. For the switch device, optimum voltage application unit time was determined. Optimum diameter of OWSMA wire was determined by applying 3.7V to the pre-determined candidate diameters, which demonstrated two-way operation in previous studies. In order to evaluate the optimum voltage application time, the internal diameter of the actuator was measured while increasing and decreasing by 50 ms from the unit time of voltage application. Delay time under two-way operation of the actuator was measured to minimize interference caused by heat between channels. Power of 3.7V was applied to OWSMA for assessment of optimal time, and the whole process from heating to cooling was video-recorded with a thermal image camera to determine the point of time at which the temperature of OWSMA wire dropped below the phase transformation temperature. The results showed that $0.4{\Phi}$ was the most suitable diameter, and the optimum unit time of voltage applied to open and close the actuator was 4100ms. It was also shown that the delay time should be more than 1.8 seconds between two-way operations of the actuator.

• Journal of Applied Biological Chemistry
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• v.54 no.4
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• pp.252-257
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• 2011

To remove excess nitrate from the agricultural environments, Enterobacter amnigenus GG0461 has been isolated as a bacterial strain having high capability of nitrate uptake activity. This strain was able to remove nitrate more than 3,000 ppm (50 mM) in the Pseudomonas agar F (PAF) medium. Therefore, it could be a candidate strain for a nitrate scavenger in the various contaminated environments, such as agricultural soils, livestock sewage, and industrial wastewater. In order to develop medium for the large-scale production of the strain GG0461, each component of PAF medium was replaced with the corresponding commercial product and the optimal conditions for bacterial growth and nitrate uptake activity were measured. Glycerol was replaced with the commercially available product and the nitrogen source was substituted with commercial tryptone, yeast extract, soybean meal, and fermented fish extract. Bacterial growth and nitrate uptake activity were maximal in the media containing 2% tryptone, followed by yeast extract, soybean meal, and fermented fish extract. The pH of the growth medium containing 2% tryptone was decreased by the bacterial nitrate uptake, suggesting that the nitrate uptake is mediated by a nitrate/proton antiporter. This result shows that the medium containing commercial tryptone was good enough for the physiological activity of the strain GG0461. Each component of PAF medium was successfully replaced with the corresponding commercial product except peptone. In conclusion, the composition of medium for the cultivation of the strain GG0461 was determined as 2% tryptone, 1% glycerol, plus required salts according to the composition of PAF medium.

• Journal of Applied Biological Chemistry
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• v.54 no.2
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• pp.79-83
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• 2011

Over-application of nitrogen fertilizer keeps increasing the salinity in the soils of greenhouse in domestic agriculture. In order to remove the excess amounts of soil nitrate, soil microorganisms which have high capacity of nitrate uptake were isolated from the upland soils and their nitrate uptake activities were measured. Strain GS2 was able to remove 50 mM nitrate within 12 h. After sequence comparison analysis of 16S rRNA gene, the strain was identified and named as Bacillus sp. GS2. When the growth and nitrate uptake activities were measured, maximal values were obtained at $30-40^{\circ}C$ and $37^{\circ}C$, respectively; however, both were optimal at pH 6-8. In the media containing 50 mM nitrate, Bacillus sp. GS2 removed 43 mM nitrate which is corresponding to 86% removal. Similar amounts of nitrate removal were observed at the nitrate concentrations up to 300 mM, showing a saturation in nitrate uptake at concentrations above 50 mM. These results imply that Bacillus sp. GS2 can be a good candidate for the microbial remediation of accumulated environmental nitrate because of its excellent growth and nitrate uptake activity.