• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.135-144
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• 2021

In this study, we investigated the characteristics of the process of hydrogen production using boil-of gas (BOG) generated from an LNG-fueled ship and the application of hydrogen fuel cell systems as auxiliary engines. In this study, the BOG steam reformer process was designed using the UniSim R410 program, and the reformer outlet temperature, pressure, and the fraction and consumption of the product according to the steam/carbon ratio (SCR) were calculated. According to the study, the conversion rate of methane was 100 % when the temperature of the reformer was 890 ℃, and maximum hydrogen production was observed. In addition, the lower the pressure, the higher is the reaction activity. However, higher temperatures have led to a decrease in hydrogen production owing to the preponderance of adverse reactions and increased amounts of water and carbon dioxide. As SCR increased, hydrogen production increased, but the required energy consumption also increased proportionally. Although the hydrogen fraction was the highest when the SCR was 1.8, it was confirmed that the optimal operation range was for SCR to operate at 3 to prevent cocking. In addition, the lower the pressure, the higher is the amount of carbon dioxide generated. Furthermore, 42.5 % of the LNG cold energy based on carbon dioxide generation was required for cooling and liquefaction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3C
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• pp.201-207
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• 2006

Soil tests are generally conducted using a membrane to measure a pore water pressure. However, it has also been recognized that the membrane penetrates into the specimen by the change of the confining pressure, and it results in the erroneous measurement in the pore water pressure and the volumetric strain. This study examined the effectiveness of the correction equation of the membrane penetration on the basis of the experimental data acquired during the isotropic unloading and the cyclic shear process using the hollow cylindrical shear test equipment. The results showed that the membrane penetration by the correction equation could be overestimated when the mean effective stress was lower than 20kPa in this study. The limitations originated from the sudden increase near the zero effective stress, and in order to prevent the overestimation in low effective stress condition, the use of the constant a was proposed in this study. Furthermore, the correction equation for the membrane penetration had to be applied carefully when the initial relative density was high and the density changes were occurred by the relocation of the soil particle by the liquefaction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.181-194
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• 2013

Landslides are known as gravitational mass movements that can carry the flow materials ranging in size from clay to boulders. The various types of landslides are differentiated by rate and depositional features. Indeed, flow characteristics are observed from very slow-moving landslides (e.g., mud slide and mud flow) to very fast-moving landslides (e.g., debris avalanches and debris flows). From a geomechanical point of view, shear-rate-dependent shear strength should be examined in landslides. This paper presents the design of advanced ring-shear apparatus to measure the undrained shear strength of debris flow materials in Korea. As updated from conventional ring-shear apparatus, this apparatus can evaluate the shear strength under different conditions of saturation, drainage and consolidation. We also briefly discussed on the ring shear apparatus for enforcing sealing and rotation control. For the materials with sands and gravels, an undrained ring-shear test was carried out simulating the undrained loading process that takes place in the pre-existing slip surface. We have observed typical evolution of shear strength that found in the literature. This paper presents the research background and expected results from the ring-shear apparatus. At high shear speed, a temporary liquefaction and grain-crushing occurred in the sliding zone may take an important role in the long-runout landslide motion. Strength in rheology can be also determined in post-failure dynamics using ring-shear apparatus and be utilized in debris flow mobility.

• Journal of Food Hygiene and Safety
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• v.35 no.1
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• pp.83-92
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• 2020

This study investigated the optimal conditions of enzymatic reaction for production of isomaltooligosaccharides (IMO) using rice flour. To manufacture IMO, commercial enzymes (Termamyl 2X, Maltogenase L, Promozyme D2, Fungamyl 800L and Transglucosidase L) were used. The sugar composition and amount of IMO were examined by HPLC with charged aerosol detector (HPLC-CAD) in each manufacturing process. Liquefaction reaction was performed according to different Termamyl 2X concentrations (0.025%, 0.05%, 0.075%, 0.1%) and reaction times (1 h, 2 h). As a result, the reducing sugar content was the highest at 138.26 g/L when 0.075% Termamyl 2X was added for 2 hours. In order to optimize simultaneous saccharification and transglucosylation, experiments on enzyme selection, enzyme concentration and enzyme reaction time were conducted. Reaction with 0.0015% Maltogenase L, 0.05-0.1% Promozyme D2 and 0.1% Tansglucosidase L was effective in decreasing glucose content and increasing content of IMO with a high degree of polymerization. A change in sugar content was observed every 6 hours to determine the optimal reaction time, and the highest IMO was produced after 36 hours of reaction (75.36 g/L). The IMO prepared under optimal conditions showed isomaltose, 35.11 g/L; panose, 11.97 g/L; isomaltotriose, 19.95 g/L; isomaltotetraose, 7.46 g/L; isomaltopentaose, 1.05 g/L at 18 brix and the ratio of IMO in the total sugar was 56.37%.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.2
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• pp.128-134
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• 2024

Asphalt-based waterproofing materials for bridge decks face issues such as softening or liquefaction of the material during the process of pouring hot asphalt concrete on top of the waterproofing layer. This leads to instability and reduced thickness of the waterproofing layer. To address these problems, new solutions beyond the existing materials, including the development and adoption of new materials, are required. Therefore, this study investigates the properties of MMA(Methyl Methacrylate) coating waterproofing material, which meets the basic physical properties for bridge deck waterproofing. We examined the overall quality standards in a system where the substrate concrete, waterproofing material, and paving layer are integrated. The study confirmed the applicability of MMA coating waterproofing material on bridge decks. The results indicate that a stable application of MMA coating waterproofing material for civil engineering structures' bridge decks can be achieved with a mix ratio of hard MMA resin : soft MMA resin : powder = 6 : 34 : 60. Additionally, when using emulsified asphalt with hardening characteristics for the adhesion between the dissimilar materials of MMA waterproofing and asphalt concrete, it is expected to meet the minimum quality standards of the Ministry of Land, Infrastructure, and Transport's 'Guidelines for Asphalt Concrete Pavement Construction (2021.07)'.

• Journal of the Korean Institute of Gas
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• v.22 no.1
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• pp.37-44
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• 2018

As the international Maritime Organization is tightening up the emission regulation vessel, many countries and companies are pushing ahead the LNG fuel as one of long term solution for emission problems of ship. as a study on the way to conduct business for LNG bunkering around the world, this study was analyzed in view-point of business models focused on major countries such as Japan, China, Singapore, Europe and United States. The results of this study are as follows. China first established a nation-centered LNG bunkering policy. And then, the state and the energy company have been cooperating and carrying on LNG bunkering business for LNG fueled ships. Some countries in Europe and United States are in the process of LNG bunkering business mainly with private company. To obtain cheaper LNG fuel than bunker-C, the private company has a business model of LNG bunkering on their own LNG fueled ships, while securing LNG with high price competitiveness through partnership with middle class operators such us LNG terminal and natural gas liquefaction plant. Also, the LNG bunkering business around the world is focused on private companies rather than public corporations, but it was going to be focused on large energy companies because the initial cost required to build LNG bunkering infrastructure. Three models (TOTE model, Shell model, ENGIE model) of LNG bun kering business are currently being developed. It has been found that the way in which LNG bunkering business is implemented by different countries is applied differently according to the enterprise and national policy.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.2
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• pp.156-163
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• 2007

This study was conducted to evaluate the liquefying efficiency of mixed organic fertilizer in different conditions. The organic fertilizer was composed of sesame oil cake, rice bran, fish meal, ground bone meal etc, and made by fermenting process. It included $23g\;kg^{-1}$, $17.0g\;kg^{-1}$, $23.9g\;kg^{-1}$, $290g\;kg^{-1}$ of N, $P_2O_5$, $K_2O$, organic matter, respectively. In one test, the mixed organic fertilizer was added in the proportion of 10% to water 90% and aerated continuously, for 2, 8 hours per day, and not aerated as control. In the other test, ratios of organic fertilizer to water were 5%, 10%, 20% and aerated for 2 hours a day. With the increase of liquefying time, pH, EC and $NH_4-N$ increased without relation to aeration time. After 10 days, liquid organic fertilizer aerated for 2 hours a day contained $634mg\;N\;kg^{-1}$, $68.1mg\;P_2O_5\;kg^{-1}$, $453mg\;K_2O\;kg^{-1}$, which was not significantly different from 8 hours a day or continuous aeration. Then extraction ratios of inorganic contents were 27.6%, 4.0% and 18.9%, respectively. Continuous aeration resulted in increasing the viable number of aerobic bacteria, spore forming bacteria and fungi in liquefied solution. Higher ratio of organic fertilizer to water increased EC, $NH_4-N$ and other inorganic matter contents, but decreased extraction ratio of nutrients in liquid fertilizer. The liquid organic fertilizer of 20% contained $1,140mg\;N\;kg^{-1}$, $35.4mg\;P_2O_5\;kg^{-1}$, $544mg\;K_2O\;kg^{-1}$ after 10 days. Then extraction ratios were 24.8%, 2.4% and 13.6%, respectively. The ratio of organic fertilizer to water was positively correlated with only spore forming bacteria, Pseudomonas spp. among microorganisms.