• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.5
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• pp.332-340
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• 2015

Acoustic emission (AE) is an effective nondestructive test that uses transient elastic wave generated by the rapid release of energy within a material to detect any further growth or expansion of existing defects. Over the past decades, because of environmental issues, the use of compressed natural gas (CNG) as an alternative fuel for vehicles is increasing because of environmental issues. For this reason, the importance and necessity of detecting defects on a CNG fuel tank has also come to the fore. The conventional AE method used for source location is highly affected by the wave speed on the structure, and this creates problems in inspecting a composite CNG fuel tank. Because the speed and dispersion characteristics of the wave are different according to direction of structure and laminated layers. In this study, both the conventional AE method and the energy based contour map method were used for source location. This new method based on pre-acquired D/B was used for overcoming the limitation of damage localization in a composite CNG fuel tank specimen which consists of a steel liner cylinder overwrapped by GFRP. From the experimental results, it is observed that the damage localization is determined with a small error at all tested points by using the energy based contour map method, while there were a number of mis-locations or large errors at many tested points by using the conventional AE method. Therefore, the energy based contour map method used in this work is more suitable technology for inspecting composite structures.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.3-3
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• 2017

The question of how to establish sustainable agricultural systems has become as prominent as questions related to water, energy and climate change. High input/high output agriculture has brought with it many adverse effects; the massive deterioration of soil and water in both quantity and quality, increased greenhouse gas emissions and an increased prevalence of unsafe foods. Additionally, urbanization and climate change has worsened the shortage of farmland and reduced the supply of agricultural water. Given these challenges, maintaining, conserving and efficiently using agri-environmental resources, through fostering of sustainable agriculture, have emerged as key tasks in solving these problems. What is needed therefore is research, based on systematic and comprehensive empirical analyses, that can propose plans and methods for establishing an appropriate sustainable agricultural system. The empirical analysis of sustainable agricultural system is approached separately from economic, environmental and social aspects. An analysis of environment effect reveals that the available phosphate level is 1.3~2.1 times greater than the optimal amount in rice paddies, upland fields and orchards. Further examination has revealed that the excess nutrient is polluting both ground water and surface water. Analytical results for economic feasibility show that factors of production have been invested heavily in the rice crop. Under these conditions, sustainable agriculture, including low-input agriculture, appears to be a possible alternative that will facilitate simultaneous improvements in both economic feasibility and environment effects. Analysis results for sociality reveal that social factors include the value of producer, association and interior networks. Social conditions are comprised of leadership, consumers' awareness, education and conflict solutions. In addition, analysis as to the degree investments contribute to improving agricultural value added has revealed that the direct payment program is the most effective instrument. Experts confirm that economic feasibility can be improved by scientific and well-reasoned nutrient management on the basis of soil testing. Farmers pointed to 'economic factors' as being the largest obstacle to switching to the practice of sustainable agriculture. They also indicate 'uncertainty with regards to sustainable agriculture technology' as an impediment to practicing sustainable agriculture. Even so, farmers who believe environmental and regional issues to be the most pressing problems have expanded their practice of sustainable agriculture. The keys to establishing sustainable agriculture system are classified into the following four aspects. Firstly, from an economic aspect, the research indicates that agricultural policy needs to be integrated with environmental policy and that the function of market making based on the value chain needs to be revitalized. Secondly, from an environmental aspect, there is a need for an optimal resource management system to be established in the agricultural sector. In addition, sustainable agriculture practice will need to be extended with attendant environmentally-friendly and sustainable intensive technology also requiring further development. Thirdly, from a social aspect, green agriculture management needs to be fostered, technology and education extended, and social conflict mediated. Lastly, from a governance aspect, it will be necessary to strengthen good governance, assign and share suitable roles and responsibilities, build a cooperation system and utilize community supported agriculture.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.215-224
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• 2018

Influences of the magnetic field on 5, 10 and 15 wt% (1.5, 3 and 4.5 M) HCl solution behaviour, which has widespread applications in petroleum well acidizing, were investigated in various conditions. Differences in the pH of magnetized hydrochloric acid compared to that of normal hydrochloric acid were measured. Taguchi design of experimental (DoE) method were used to model effects of the magnetic field intensity, concentration, velocity and temperature of acid in addition to the elapsed time. The experimental results showed that the magnetic field decreases [$H^+$] concentration of hydrochloric acid up to 42% after magnetization. Increasing the magnetic field intensity (with 28% contribution), concentration (with 42% contribution), and velocity of acid increases the effect of magnetic treatment. The results also demonstrated that the acid magnetization was-not influenced by the fluid velocity and heating. It was also displayed that the acid preserves its magnetic memory during time. The optimum combination of factors with respect to the highest change of [$H^+$] concentration was obtained as an acid concentration of 10% and an applied magnetic field of 4,300 Gauss. Due to the reduction of HCl reaction rate under the magnetization process, it can be proposed that the magnetized HCl is a cost effective and reliable alternative retarder in the matrix acidizing of hydrocarbon (crude oil and natural gas) wells.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.1-6
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• 2007

In view of energy supply, biogas can be seen as alternative fuel by substituting considerable amount of fossil fuel and may be utilized for heat and power production or for transport fuel production ($CH_4-enriched$ biogas). The aim of this research is to analyse the emission of $NO_x$ and CO from biogas fired combustion engine for electric power production. The result indicate a significant effect of biogas composition ($CH_4-CO_2$ ratio) and biogas flow rate on the air pollutants emission. The emission factors from this study were compared with those of U.S. EPA. Low $CH_4-CO_2$ ratio condition typically shows the lower $NO_x$ and CO emission than higher $CH_4-CO_2$ ratio condition. At normal $CH_4-CO_2$ ratio (7:3) emission factors of $NO_x$ and CO were 1.29 and 30.43 g/MMBtu, respectively. At low $CH_4-CO_2$, ratio (6:4) emission factors of $NO_x$ and CO were 0.646 and 60.86 g/MMBtu, respectively, It should be emphasized that the actual emission may vary considerably from these results due to operating conditions including torque load and engine speed.

• Journal of Trauma and Injury
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• v.19 no.1
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• pp.67-73
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• 2006

Purpose: The arterial base deficit (BD) has proven to be useful in the evaluation and management of trauma patients. Indicators such as the Triage-Revised Trauma Score (t-RTS) and the systemic inflammatory response syndrome (SIRS) score have been used as triage tools for emergency trauma patients in Korea. The purpose of this study was to assess the usefulness of the initial BD in predicting injury severity and outcome in the trauma population. Methods: The medical records of 308 consecutive trauma patients admitted to the Emergency Center of Masan Samsung Hospital from January 2004 to December 2004 were carefully examined prospectively and retrospectively, and 291 patients were selected as subjects for this research. The SIRS score and the t-RTS were calculated based on the records from the emergency department, and the BD was calculated based on the arterial blood gas analysis obtained within 30 minutes of admission. The efficiency of the three indicators as triage tools was evaluated by using cross tabulations in two - by - two matrices and by using a receiver operating characteristic (ROC) curve analysis. Results: When the mortality was used as the outcome parameter, the sensitivity and the accuracy of the initial BD were higher than those of the SIRS score (p<0.05) and were same as those of the t-RTS. The areas under the ROC curves of the initial BD, the SIRS score, and the t-RTS were $0.740{\pm}0.087$, $0.696{\pm}0.082$, and $0.871{\pm}0.072$, respectively (95% confidence interval). When emergency operation and blood transfusion requirements were used as outcome parameters, the comparisons of the sensitivities and the accuracies of the initial BD and the other two indicators showed the same pattern as mentioned above. The areas under the ROC curves of the initial BD were 0.7~0.8 and were larger than those of the SIRS score (p<0.05). Conclusion: The ability of the initial BD to predict injury severity and outcome was similar to those of the t-RTS and the SIRS score. Therefore, the authors suggest that the initial BD may be used as an alternative to previous triage tools for trauma patients.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.2
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• pp.55-65
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• 1999

AF(anaerobic filter)/BAF(biological aerated filter) system and UASB(upflow anaerobic sludge blanket)/BAF system, of which system effluents were recirculated to the anaerobic reactors in each system, were operated in order to investigate the performance in simultaneous removal of organics and nitrogen in high-strength dairy wastewater. Advanced anaerobic treatment processes of AF and UASB were evaluated on applicability as pre-denitrification reactors, and BAF was also evaluated on the performance in oxidizing the remaining organics and ammonia nitrogen. At system HRTs of 4.0 to 4.5 days and recirculation ratios of one to three, the AF/BAF system could achieve more than 99% of organics removals and 64 to 78% of total nitrogen removals depending upon the recirculation ratio. Although the UASB/BAF system also showed more than 99% of organics removals, total nitrogen removals in the UASB/BAF system were 53 to 66% which are lower than those in the AF/BAF system at the corresponding recirculation ratios. Optimum recirculation ratios considering simultaneous removal of organics and nitrogen and cost-effectiveness, were in the range of two to three. The upflow AF packed with crossflow module media, as a primary treatment of the anaerobic reactor/BAF system, showed better performances in denitrification, SS removals, and gas production than the UASB. Higher loading rate of suspended solids from the UASB increased the backwashing times in the following BAF. Especially, at a recirculation ratio of three in the UASB/BAF system, the increase in head loss due to clogging in the BAF caused frequent backwashing, at least once d day. The BAF showed the high nitrification efficiency of average 99.2% and organics removals more than 90% at organics loading rate less than $1.4KgCOD/m^3/d$ and $COD/NH_3-N$ ratio less than 6.4. It was proved that the simplified anaerobic reactor/BAF system could maximize the organics removal and achieve high nitrogen removal efficiencies through recirculation of system effluents to the anaerobic reactor. The AF/BAF system can, especially, be a cost effective and competitive alternative for the simultaneous removal of organics ana nitrogen from wastewaters.

• Journal of Chest Surgery
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• v.31 no.2
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• pp.142-148
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• 1998

Video-assisted thoracic surgery(VATS) is emerging as a viable alternative to thoracotomy when surgical treatment of spontaneous pneumothorax is required. 20 patients with spontaneous pneumothorax underwent bullectomy between July 1995 and May 1996. The patients were divided into two groups : Control group ; the patients who received with mid-axillary approach(n=10), Experimental group ; the patients who received with VATS (n=10). The results were as follows ; 1. The total sex distribution was male predominance (male:female=17:3). Mean age of control group was 29.6$\pm$9.8 years and experimental group was 27.2$\pm$11.9 years. 2. The mean period of postoperative chest tube indwelling duration and hospital stay were 3.3$\pm$0.8 days and 7.9$\pm$1.2 days in control group and 2.1$\pm$0.9 days and 5.2$\pm$3.1 days in experimental group(p=0.005 and p=0.02). 3. The mean time of operation, vital signs and arterial blood gas analysis did not showed any statistical differences between the groups. 4. Percent recovery of tidal volume and forced vital capacity were significantly improved in experimental group comparing with control group (p<0.05). 5. The patients undergoing VATS experienced significantly less postoperative pain and limitation of motion. In conclusion, VATS is safe and offers the potential benefits of shorter postoperative hospital stays and less pain with cosmetic benefits.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.2
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• pp.285-294
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• 2011

The abatement of methane emission from ruminants is an important global issue due to its contribution to greenhouse gas with carbon dioxide. Methane is generated in the rumen by methanogens (archaea) that utilize metabolic hydrogen ($H_2$) to reduce carbon dioxide, and is a significant electron sink in the rumen ecosystem. Therefore, the competition for hydrogen used for methanogenesis with alternative reductions of rumen microbes should be an effective option to reduce rumen methanogenesis. Some methanogens parasitically survive on the surface of ciliate protozoa, so that defaunation or decrease in protozoa number might contribute to abate methanogenesis. The most important issue for mitigation of rumen methanogenesis with manipulators is to secure safety for animals and their products and the environment. In this respect, prophylactic effects of probiotics, prebiotics and miscellaneous compounds to mitigate rumen methanogenesis have been developed instead of antibiotics, ionophores such as monensin, and lasalocid in Japan. Nitrate suppresses rumen methanogenesis by its reducing reaction in the rumen. However, excess intake of nitrate causes intoxication due to nitrite accumulation, which induces methemoglobinemia. The nitrite accumulation is attributed to a relatively higher rate of nitrate reduction to nitrite than nitrite to ammonia via nitroxyl and hydroxylamine. The in vitro and in vivo trials have been conducted to clarify the prophylactic effects of L-cysteine, some strains of lactic acid bacteria and yeast and/or ${\beta}$1-4 galactooligosaccharide on nitrate-nitrite intoxication and methanogenesis. The administration of nitrate with ${\beta}$1-4 galacto-oligosaccharide, Candida kefyr, and Lactococcus lactis subsp. lactis were suggested to possibly control rumen methanogenesis and prevent nitrite formation in the rumen. For prebiotics, nisin which is a bacteriocin produced by Lactococcus lactis subsp. lactis has been demonstrated to abate rumen methanogenesis in the same manner as monensin. A protein resistant anti-microbe (PRA) has been isolated from Lactobacillus plantarum as a manipulator to mitigate rumen methanogenesis. Recently, hydrogen peroxide was identified as a part of the manipulating effect of PRA on rumen methanogenesis. The suppressing effects of secondary metabolites from plants such as saponin and tannin on rumen methanogenesis have been examined. Especially, yucca schidigera extract, sarsaponin (steroidal glycosides), can suppress rumen methanogenesis thereby improving protein utilization efficiency. The cashew nutshell liquid (CNSL), or cashew shell oil, which is a natural resin found in the honeycomb structure of the cashew nutshell has been found to mitigate rumen methanogenesis. In an attempt to seek manipulators in the section on methane belching from ruminants, the arrangement of an inventory of mitigation technologies available for the Clean Development Mechanism (CDM) and Joint Implementation (JI) in the Kyoto mechanism has been advancing to target ruminant livestock in Asian and Pacific regions.

• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.320-328
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• 2014

Biodiesel has very similar physical properties (density, kinematic viscosity) and has even higher cetane number compare with conventional diesel. There are no necessity to change or modify the infra-structure & engine system. It is known that fatty acid methyl ester (FAME) is oxygen-contained components increasing the combustibility, biodegradability and reduced the exhaust harmful gas. These things made the biodiesel more popular as an alternative diesel fuel. But biodiesel's sources are controversial issues about $CO_2$ reduction effect at this time because those mainly come from edible plants such as soy, palm, rapeseed already spent lot of $CO_2$ to cultivate. Whereas micro-algae is focused because they are inedible and has rapid growth rates & high carbon-dioxide adsorption rate per area. In this study, we analyze the each FAME components using $GC{\times}GC$-TOFMS in stead of GC-FID and verify the previous total FAME contents method's applicability through the micro algal biodiesel derived from Dunaliella tertiolecta.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.222-229
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• 2017

High manganese steel exhibits excellent mechanical properties with respect to strength and durability at low temperatures. Recently, high manganese steel has been considered as an alternative to existing materials, such as nickel steel and SUS304L for application as tank material for Liquefied Natural Gas (LNG) cargo containment systems. In the present study, tensile tests were performed at room and cryogenic temperatures in order to investigate the mechanical properties and non-linear tensile behavior of high manganese steel. In addition, elasto-plastic damage model was applied using the finite element analysis software ABAQUS via a user defined material subroutine (UMAT) to describe the material behavior. Finally, the results of the finite element simulations using the UMAT were compared to those of the tensile tests in order to validate the proposed UMAT. It has been demonstrated that the UMAT can effectively describe the non-linear tensile behavior of high manganese steel.