• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.9-16
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• 2016

Buried pipe system is subject to leak or rupture due to internal and external defects with age. Especially, if the pipeline is designed for pressurized gas, the leak can wreak a devastating on its surrounding area. The current method of setting up underground gas pipeline is based on OGP criteria of applying one tenth of the inner pipe pressure. The criteria is applied irrespective of their burial depth or pipe's properties. At times, even the whole safety measures are totally ignored. Considering the magnitude of possible damage from a gas leakage, a precise analytical tool for the risk assessment is urgently needed. The study was conducted to assess possible scenarios of gas accidents and to develop a computer model to minimize the damage. The data from ETA was analyzed intensively, and the model was developed. The model is capable of predicting jet fire influence area with comprehensive input parameters, such as burial depth. The model was calibrated and verified by the historic accident data from Edison Township, New Jersey, the United States. The statistical model was also developed to compare the results of the model in this study and the existing OGP model. They were in good agreement with respect to damage predictions, such as radiation heat coming from 10 meters away from the heat source of gas flame.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.6
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• pp.399-409
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• 2017

This study numerically investigates the characteristics of the velocity field including the average flow velocity, longshore current and turbulent kinetic energy acting as the main external forces of the salient formed behind the permeable submerged breakwaters. Shoreline response is also predicted by the longshore-induced flux. In this paper, a three-dimensional numerical wave tank based on the OLAFOAM, CFD open source code, is utilized to simulate the velocity field around permeable submerged breakwaters under the formation condition of salient. The characteristics of the velocity field around permeable submerged breakwaters with respect to the gap width between breakwaters and the installing position away from the shoreline under a range of regular waves for different wave height are evaluated. The numerical results revealed that as the gap width between breakwaters increases, the longshore currents become stronger. Furthermore, as the gap width becomes narrower, the point where flow converges moves from the center of the breakwater to the head part. As a result, it is possible to understand the formation of the salient formed behind the submerged breakwaters. In addition, it was found that the longshore currents caused by the gap width between breakwaters and the installation position away from the shoreline are closely related to the turbulent kinetic energy.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.306-309
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• 2007

PXLM(Phosphor based x-ray light modulator) has a combined structure by phosphor, photoconductor, and liquid crystal and it can realize x-ray image of high resolution in clinical diagnosis area. In this study, we fabricated a photoconductor and investigated electrical and optical properties to confirm application possibility of radiator detector of PXLM structure. As photoconductor, amorphous selenium(a-Se), which is used most in DR(Digital radiography) of direct conversion method, was used and for formation of thin film, it was formed as $20{\mu}m-thick$ by using thermal vacuum evaporation system. For a produced a-Se film, through XRD(X-ray diffraction) and SEM(Scanning electron microscope), we investigated that amorphous structure was uniformly established and through optical measurement, for visible light of 40 $0\sim630nm$, it had absorption efficiency of 95 % and more. After fabricated a-Se film on the top of ITP substrate, hybrid structure was manufactured through forming $Gd_2O_3:Eu$ phosphor of $270{\mu}m-thick$ on the bottom of the substrate. As the result to confirm electrical property of the manufactured hybrid structure, in the case of appling $10V/{\mu}m$, leakage current of $2.5nA/cm^2$ and x-ray sensitivity of $7.31nC/cm^2/mR$ were investigated. Finally, we manufactured PXLM structure combined with hybrid structure and liquid crystal cell of TN(Twisted nematic) mode and then, investigated T-V(Transmission vs. voltage) curve of external light source for induced x-ray energy. PXLM structure showed a similar optical response with T-V curve that common TN mode liquid crystal cell showed according to electric field increase and in appling $50\sim100V$, it showed linear transmission efficiency of $12\sim18%$. This result suggested an application possibility of PXLM structure as radiation detector.

• Archives of design research
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• v.13 no.4
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• pp.85-93
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• 2000

Design becomes a source of new competitive power in the boundless global market so-called globalization. The competitive power in business was lied in the technology in 70's and the design was understood as a styling or graphic means. However, the design has become more important means to get the competitive power in business since 1980. World businesses have found the fact that it has a super competitive power to make the product's performance as well as its dignity rather than it is to determine the product's external view or color. The change of design policy in Phillips, one of the world's leading producers of electronic products, is not much different. Design manager's power was limited until 70's. However, Phillips has focused its business strategy on the higher competitive power since 1980 and they welcomed Robert Blaich, vice president of design and development at Herman Miller Inc., to be a member of the company, expanding the importance of design along with restructure while working on the globalization. Meanwhile, Stefano Marzano, a Senior Director in 90's, established a high design concept, working on the strategic futures to get customer-oriented and for successful commercialization. The vision of the future developed over 3 years until 1996 was to forecast 10 years coming up and create a new value while achieving the business target through the design as an innovative design in bracing for the information network era.

• Journal of Animal Science and Technology
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• v.49 no.2
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• pp.279-286
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• 2007

A submerged biofilm sequencing batch reactor (SBSBR) process, which liquor was internally circulated through sandfilter, was designed, and performances in swine wastewater treatment was evaluated under a condition of no external carbon source addition. Denitrification of NOx-N with loading rate in vertical and slope type of sandfilter was 19% and 3.8%, respectively, showing approximately 5 times difference, and so vertical type sandfilter was chosen for the combination with SBSBR. When the process was operated under 15 days HRT, 105L/hr.m3 of internal circulation rate and 54g/m3.d of NH4-N loading rate, treatment efficiencies of STOC, NH4-N and TN (as NH4-N plus NOx-N) was 75%, 97% and 85%, respectively. By conducting internal circulation through sandfilter, removal performances of TN were enhanced by 14%, and the elevation of nitrogen removal was mainly attributed to occurrence of denitrification in sandfilter. Also, approximately 57% of phosphorus was removed with the conduction of internal circulation through sandfilter, meanwhile phosphorus concentration in final effluent rather increased when the internal circulation was not performed. Therefore, It was quite sure that the continuous internal circulation of liquor through sandfilter could contribute to enhancement of biological nutrient removal. Under 60g/m3.d of NH4-N loading rate, the NH4-N level in final effluent was relatively low and constant(below 20mg/L) and over 80% of nitrogen removal was maintained in spite of loading rate increase up to 100g/m3.d. However, the treatment efficiency of nitrogen was deteriorated with further increase of loading rate. Based on this result, an optimum loading rate of nitrogen for the process would be 100g/m3.d.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.8
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• pp.852-859
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• 2006

The novel microbial process such as Anammox(anaerobic ammonium oxidation) and Canon(completely autotrophic nitrogen removal over nitrite) processes is promising biotechnology to remove nitrogen from ammonium-rich wastewater like anaerobic sludge digester liquid. In this research, a new Canon-type nitrogen removal process adopting upflow granular sludge bed type configuration was investigated on its feasibility and process performance, using synthetic wastewater and sludge digester liquids. Air as an oxygen source was provided in an external aeration chamber with flow recirculation. In the first experiment using the synthetic wastewater(up to 110 mg $NH_4$-N $L^{-1}$), the ammonium removal was about 95%(92% for T-N) at effective hydraulic retention time(HRT) for 3.8 days. In the second experiment using the sludge digester liquids($438{\pm}26$ mg $NH_4$-N $L^{-1}$), the total nitrogen removal was $94{\pm}1.7%$ at HRT for 5.4 days and $76{\pm}1.5%$ at HRT for 3.8 days, respectively. Little nitrite and nitrate were observed in the effluent of both experiments. The process revealed quite a lower oxygen($0.29{\sim}0.59$ g $O_2$ $g^{-1}N$) and less alkalinity($3.1{\sim}3.4$ g $CaCO_3$ $g^{-1}N$) consumption as compared to other new technology in microbial nitrogen removal. The process also offers the economical compact reactor configuration with excellent biomass retention, resulting in lower cost for investment and maintenance.

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.286-296
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• 2010

The study of the development of DJ robots is to meet the demands of the music services which are changing very rapidly in the digital and network era. Existing studies, as a whole, develop music services on the premise of personalized environment and equipment, but the DJ robot is on the premise of the open space shared by the public. DJ robot gives priority to traditional space and music. Recently as the hospitality and demand for cultural contents of South Korea expand to worldwide, industrial use of the contents based on traditional or our unique characteristics is getting more and more. Meanwhile, the DJ robot is composed of a combination of two modules. One is to detect changes in the external environment and the other is to set the properties of the music by psychology, emotional engineering, etc. DJ robot detect the footprint of the temperature, humidity, illumination, wind, noise and other environmental factors measured, and will ensure the objectivity of the music source by repeated experiments and verification with human sensibility ergonomics based on Hevner Adjective Circle. DJ robot will change the soundscape of the traditional space being more beautiful and make the revival and prosperity of traditional music with the use of traditional music through BGM.

• Journal of Advanced Navigation Technology
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• v.19 no.5
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• pp.423-432
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• 2015

This paper shows that design, manufacture and the performance of FC-NIC (fibre channel network interface card) for network unit configuration which is based on one of the 5 main configuration items of the common functional module for IMA (integrated modular Avionics) architecture. Especially, FC-NIC uses zynq SoC (system on chip) for host load reductions. The host merely transmit FC destination address, source memory location and size information to the FC-NIC. After then the FC-NIC read the host memory via DMA (direct memory access). FC upper layer protocol and sequence process at local processor and programmable logic of FC-NIC zynq SoC. It enables to free from host load for external communication. The performance of FC-NIC shows average 5.47 us low end-to-end latency at 2.125 Gbps line speed. It represent that FC-NIC is one of good candidate network for IMA.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1205-1212
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• 2000

The effect of temperature on the sources of organic acids and sludge when phosphorus was biologically released was evaluated in this study. The sludge used in this study was obtained from sequencing batch reactor processing the swine wastewater. Temperature is one of the most important parameters influencing the phosphorus release. As a result, the rate of phosphorus released was increased as the temperatures were increased from 5 to $30^{\circ}C$ regardless of the sources of organic acids used. Under anaerobic conditions, as acetate, propionate, glucose, and domestic wastewater were used as the sources of organic acids, the corresponding activation energy($E_a$) values were 49.83, 55.82, 54.61, and 45.44 KJ/mol, respectively. Temperature coefficient($\theta$) values were 1.0676, 1.0826, 1.0748, and 1.0698, respectively. Therefore, the rate of phosphorus released was increased as temperature was increased, whereas, the effect, of the sources of organic acids and temperature on the activation energy and temperature coefficient values were minimal. When the sludge previously adapted to acetate as external organic source was used, the activation energy and temperature coefficient values were 44.94 KJ/mol and 1.0570 respectively. The effect of temperature was minimal. These values obtained from the sludge previously adapted to acetate were smaller than those from the sludge not previously adapted to the same organic acid. This suggest that the sludge previously adapted to acetate was less dependent on temperature than that not adapted to the acetate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.339-344
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• 2016

Since transmissions of large amounts of data are frequent, users require more bandwidth, and the need for communications networks having greater bandwidth is increasing. One communications network satisfying this need is an optical communications network. Therefore, studies to increase the transmission capacity of optical communications systems have been carried out. However, in a general optical communications system, a signal transmitted through optical fiber (a transmission medium) is detected through direct detection in the receiving system. This method has a disadvantage in that the entire bandwidth of the optical signal cannot be utilized. Also, when transmitting an optical signal, there is a problem where the signal-to-noise ratio is affected by neighboring channels. To overcome this situation, various studies are being conducted to minimize the influence of external interference and noise. This paper overcomes the situation by transmitting spectrum-sliced signals using the digital transmission system, FSK. Analyzing the characteristics of the signals detected in the receiver of the optical communications system, Gaussian distribution is used for the PDF of the spectrum-sliced signal, and the signal at the receiving end of the optical communications system is assumed to have a k-square distribution. The results of the analysis confirmed it is better to transmit the spectrally divided signal rather than transmit the laser source.