• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.40-46
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• 2011

The purpose of CBA(cost-benefit analysis) in risk assessment is to show whether the benefits of implementing additional risk reduction methods(RRMs) derived through risk assessment outweigh its costs and it is proper to implement the methods. In this paper CBA has been conducted in order to select the most effective and reasonable RRM as implementing the RRM derived after QRA for the high pressure urban gas pipelines. As conducting QRA again by applying the derived RRMs, No. 10 measure which includes pipeline corrosion monitoring, MOV(motor operated valve) installation and the method to protect pipeline damage caused by third-party mechanical interference has showed the highest risk reduction effect. Also it has been considered to be reasonably practicable by conducting CBA and then is selected as the most effective and reasonable RRM on the objects of this paper.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.703-708
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• 2011

In this paper, most of the church except for a large church has accommodated many audience to install a balcony floor in a small space. therefore, dead zone and dislocated sound image localization is made due to this under-balcony seats. This paper propose that the problems of dead zone and dislocated sound image localization could be solved using computer simulation in the view of practical side. The economical computer simulation tool, Mapp online that can be found easily was used to the specified church. Installation a sub speaker for dead zone and -10 dB power control of the sub speaker to main speaker power for dislocated sound image localization was proposed. Computer simulation result shows that the value of definition for area was improved from "Normal" to "Very Good" which means about 52% improvement.

• Spatial Information Research
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• v.20 no.5
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• pp.37-47
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• 2012

This study analyzes the changes of lifestyle and urban spaces with the advent of U-City and tries to propose a direction of urban policies reflecting them. For this, it investigates lifestyle changes to predict the phase of urban spaces in the future. In a survey on urban functionalities with downtown as the main space of activities, it was expected that traffic for the use of these functionalities would be reduced. Traffic reduction was predicted to restrain downtown from growing and weaken the concentration of downtown activity. For the reorganization of existing spaces, in particular, public spaces would be changed to multi-purpose spaces in which various urban activities can be carried out using ubiquitous technologies. With the advent of U-City and the various changes of conditions, it is expected that the demand for land use and urban planning facilities would be altered by downtown and peripheries. A planning tool with a more concrete demand estimation of the future demand in individual areas of usage should be developed and it should be reflected in urban planning. Also, with the integration of functionalities so that more efficient land use will be possible, flexible designation of usage areas is necessary. Along with this, to prevent the decline of old downtown areas and provincial cities, the balanced installation of IT-related infrastructures will precede.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.7
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• pp.373-384
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• 2017

The objective of this study was to determine the effect of refrigerant heat exchanger on the performance of type II absorption heat pump performance using numerical analysis. Two heat exchange installation methods were used: solution to refrigerant and waste hot water to refrigerant. These methods were compared to the standard model of hot water flow without using refrigerant heat exchanger. When waste hot waters were bypassed to refrigerant heat exchanger, COP was not affected. However, steam mass generation rates were increased compared to those of the standard model. When solutions were bypassed to the refrigerant heat exchanger, results were different depending on the place where the solution rejoined. COP and steam mass generation rates were lower compared to those when waste heat water was passed to refrigerant heat exchanger. Thus, it is possible to obtain higher steam mass generation rates by using waste water and installing refrigerant heat exchanger.

• Journal of Convergence for Information Technology
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• v.7 no.5
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• pp.89-93
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• 2017

As the cost of installing and maintaining software on large organizations such as recent companies and schools has increased, software installation and maintenance costs are low, system management is easy, demand for ease of use software solutions has increased. In the reality that special education for service center engineers is required along with the release of various products, training of the software and solution industry is regarded as important. Building Web-based user and system interactive environment, strengthened usability and educational ability effect suitable for engineer level. In the future, research that is familiar with specific software, not successfully combining multiple frameworks, rather than developers, will be increasingly important for research that can achieve optimal performance.

• The Journal of Korean Association of Computer Education
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• v.5 no.1
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• pp.35-43
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• 2002

By entering the information society, the trend of increasing use of the cyber education to deliver high-Quality educational programs is likely to continue. For instance, supported by the government agencies, central officials training institute is expending vast amounts of money for the installation of cyber education programs. However, much of the research that has been done concerns the discrepancy between the potential and the actual use of technology in the field of education and training. The intent of this study was to identify the decision of the adoption of cyber education among national officials who had just peceived the existence the cyber education programs which would be used for their professional training and development, and to investigate the relationships between the Rogers' five attributes of innovation (relative advantage, compatibility, easy of use, observability, trialiability) and their decision of adoption. The results of the study generally concurred with Rogers diffusion of innovation theory revealing that perceived compatibility, easy of use, and observability of cyber education are significant predictors of decision to participate in cyber education.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.212-217
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• 2015

Ships and marine structures have a lot of problems in their high maintenance and operating cost by biofouling. A biofouling occurrs by the adhesion of marine microorganism, algae and bacteria. In this study, the aim is to prevent or to reduce the biofouling phenomena through silver nano-particle coating on artificial light-weight aggregates and geopolymer. The antibacterial activity on them is tested according to ASTM E2149-2013a. The test results showed, it is estimated that silver nano-particles removed 99.99 % of bacteria. Specimens were set up in the sea side of field test area in Korea Institute of Ocean Science and Technology (KIOST) and have been observed for five months. The anti-biofouling effect and difference in weight change rate have been detected two months later after the installation. Because silver nanoparticles inhibit bacterial growth and kill the cells by destroying bacterial membranes, silver nano-particle coating on artificial lightweight aggregates is a well-suited and eco-friendly method for preventing biofouling in the sea up to 5 months.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.3
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• pp.216-222
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• 2013

Fertilizer management has the potential to promote the storage of carbon and nitrogen in agricultural soils and thus may contribute to crop sustainability and mitigation of global warming. In this study, the effects of fertilizer practices [no fertilizer (Control), chemical fertilizer (NPK), Compost, and chemical fertilizer plus compost] on soil total carbon (TC) and total nitrogen (TN) contents in inner soil profiles of paddy soil at 0-60 cm depth were examined by using long-term field experimental site at $42^{nd}$ years after installation. TC and TN concentrations of the treatments which included N input (NPK, Compost, NPK+Compost) in plow layer (0-15 cm) ranged from 19.0 to 26.4 g $kg^{-1}$ and 2.15 to 2.53 g $kg^{-1}$, respectively. Compared with control treatment, SOC (soil organic C) and TN concentrations were increased by 24.1 and 31.0%, 57.6 and 49.7%, and 72.2 and 54.5% for NPK, Compost, and NPK+Compost, respectively. However, long term fertilization significantly influenced TC concentration and pools to 30 cm depth. TC and TN pools for NPK, Compost, NPK+Compost in 0-30 cm depth ranged from 44.8 to 56.8 Mg $ha^{-1}$ and 5.78 to 6.49 Mg $ha^{-1}$, respectively. TC and TN pools were greater by 10.5 and 21.4%, 30.3 and 29.6%, and 39.9 and 36.3% in N input treatments (NPK, Compost, NPK+Compost) than in control treatment. These resulted from the formation and stability of aggregate in paddy soil with continuous mono rice cultivation. Therefore, fertilization practice could contribute to the storage of C and N in paddy soil, especially, organic amendments with chemical fertilizers may be alternative practices to sequester carbon and nitrogen in agricultural soil.

• Korean Journal of Soil Science and Fertilizer
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• v.51 no.2
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• pp.79-89
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• 2018

Subsurface drip irrigation (SDI) system is considered one of the most effective methods for water application. A 2-year field study was conducted to investigate the effect of SDI systems with various dripline spacing (0.7 or 1.4 m) and position (under furrow or ridge) on soybean (Glycine max L.) production at a sandy-loam soil in Miryang, South Korea. For 2016-2017, average grain yield in SDI irrigated plots, $3.16Mg\;ha^{-1}$, was statistically greater than rainfed irrigated plot ($2.63Mg\;ha^{-1}$). Soybean grain yield averaged $3.25Mg\;ha^{-1}$ for the 0.7 m dripline spacing and $3.07Mg\;ha^{-1}$ for the 1.4 m spacing for the two-year period compared to a rainfed irrigated average of $2.63Mg\;ha^{-1}$ for the same period. Soybean treated with SDI system had significantly greater values of normalized difference vegetation index and stomatal conductance, indicating that soybean plants in SDI plots had greater photosynthetic and stomatal activity due to the higher water availability in soil. Irrigation water use efficiency (IWUE) was greatest in the plot of 0.7 m spacing installed under ridge position than any other plot across growing season. Average soil water content in plots with 0.7 m dripline spacing was $0.21m^3\;m^{-3}$ at 5 cm depth layer, which was 45% greater compared to the plots with 1.4 m spacing, even though the gross irrigation amounts were greater in 1.4 m spacing plots. It is concluded that wide dripline spacing (1.4 m) is probably the more economical installation design for SDI system compared to 0.7 m spacing in this study soil because the initial cost for dripline may be reduced with wide spacing design, even though the IWUE is greater in the plot of 0.7 m dripline spacing.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.4
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• pp.175-184
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• 2017

With the improvement of living standards, the ventilation for the mitigation of indoor or outdoor air-pollution problems has recently attracted a lot of attention. Consequently, the ventilation for the supply of outdoor fresh air into a room is treated as an important building-design factor. The ventilation is generally divided into the forced and natural types; here, the former can control the ventilation rate by using mechanical devices, but it has the disadvantages of the equipment costs, maintenance costs, and noise generation, while the latter is applied to most workshops due to the absence of noise and the low installation and maintenance costs. In this experimental study, the ventilation performance of a typical rotating-type natural ventilator, which is called a "wind turbine," was investigated with the outdoor-wind velocity and the indoor/outdoor-temperature difference. From the experiment results, it was confirmed that the temperature difference of $10^{\circ}C$ corresponds to the ventilation driving force with an outdoor-wind velocity of 1.0 m/s. Additionally, the intake-opening area of a building also exerts a great effect on the ventilation rates.