• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.111.1-111.1
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• 2011

Recently, comsumption of fossil fuel is causing many problems(oilflation, global warming, environmental pollution). For this reason Renewable energy is now becoming the center of interest as a solution to these problems. Bioethanol, especially, is able to substitute petroleum as fuel; making it a viable and promising renewable energy. In order to production of fuel bioethanol, Dehydration process is essential. Azeotropic distillation, extractive and pressure swing absorption(PSA) process are some of possible dehydration process, out of which, PSA process is attractive since it required less energy and lower setup cost. In this study, we produced fuel bioethanol using 2-step PSA(3 bed + 2 bed) process for more efficient and economical process. Through this study, we produced fuel bioethanol using 2-step PSA process and concentration of fuel bioethanol was 99.54wt%(feed ethanol: 92.4wt%). We expected that because of efficient use of absorbents(zeolite), 2 step PSA process contribute to economical operation.

• Environmental Engineering Research
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• v.17 no.2
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• pp.89-94
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• 2012

Pyrolysis/gasification technology utilizes an energy conversion technique from various waste resources, such as biomass, solid waste, sewage sludge, and etc. to generating a syngas (synthesis gas). However, one of the major problems for the pyrolysis gasification is the presence of tar in the product gas. The tar produced might cause damages and operating problems on the facility. In this study, a gliding arc plasma reformer was developed to solve the previously acknowledged issues. An experiment was conducted using surrogate benzene and naphthalene, which are generated during the pyrolysis and/or gasification, as the representative tar substance. To identify the characteristics of the influential parameters of tar decomposition, tests were performed on the steam feed amount (steam/carbon ratio), input discharge power (specific energy input, SEI), total feed gas amount and the input tar concentration. In benzene, the optimal operating conditions of the gliding arc plasma 2 in steam to carbon (S/C) ratio, 0.98 $kWh/m^3$ in SEI, 14 L/min in total gas feed rate and 3.6% in benzene concentration. In naphthalene, 2.5 in S/C ratio, 1 $kWh/m^3$ in SEI, 18.4 L/min in total gas feed rate and 1% in naphthalene concentration. The benzene decomposition efficiency was 95%, and the energy efficiency was 120 g/kWh. The naphthalene decomposition efficiency was 79%, and the energy yield was 68 g/kWh.

• Journal of Energy Engineering
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• v.26 no.1
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• pp.76-83
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• 2017

In this paper, the carbon resources recycling of the overview of coffee waste generation in Vietnam. Since few years, there has been a significant research studies was done in the areas of coffee waste generation areas and also waste water generation from coffee production. The coffee residue (solid) and waste water (liquid) both are caused the underground water contamination and also soil contamination. These residues contain high organic matter and acid content leads to the severe threat to environment. In second stage of coffee production process, the major solid residue was generated. Various solid residues such as spent coffee grounds, defective coffee beans and coffee husks) pose several environmental concerns and specific problems associated with each type of residue. Due to the unlimited usage of coffee, the waste generation is high. At the same time, some researchers have been investigated the spent coffee wastes are the valuable sources for various valuable compounds. Biodiesel or biomass productions from coffee waste residues are the best available utilization method for preventing the landfill problems of coffee waste residues.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2840-2851
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• 2022

Electric boilers (EBs) are the backup steam source for the auxiliary steam system of high-temperature gas-cooled reactor nuclear power plants. When the plant is in normal operations, the EB is always in hot standby status. However, the current hot standby operation strategy has problems of slow response, high power consumption, and long operation time. To solve these problems, this study focuses on the optimization of hot standby operations for the EB system. First, mathematical models of an electrode immersion EB and its accompanying deaerator were established. Then, a control simulation platform of the EB system was developed in MATLAB/Simulink implementing the established mathematical models and corresponding control systems. Finally, two optimization strategies for the EB hot standby operation were proposed, followed by dynamic simulations of the EB system transient from hot standby to normal operations. The results indicate that the proposed optimization strategies can significantly speed up the transient response of the EB system from hot standby to normal operations and reduce the power consumption in hot standby operations, improving the dynamic performance and economy of the system.

• JOURNAL OF ELECTRICAL WORLD
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• no.9 s.69
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• pp.28-33
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• 1982

• JOURNAL OF ELECTRICAL WORLD
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• no.8 s.68
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• pp.24-28
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• 1982

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.72-72
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• 1999

• KIEAE Journal
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• v.14 no.1
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• pp.113-120
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• 2014

The Green growth has been demanded in all industrial sectors due to environmental destruction and exhaustion of natural resources. Buildings have consumed 1/3 of the total energy and 40% of natural resources and have accounted for 50% of $CO_2$ emissions and 30-50% of waste materials. In 1991, BREEAM(Building Research Establishment Environmental Assessment Method) of the British BRE(Building Research Establishment) had begun reduction of $CO_2$ emissions and energy saving movements, in which all the countries around the world have participated. The Republic of Korea has taken part in this trend by declaring a "National Vision in the Green Growth" in 2008 and implementing regulations on "Low Carbon, Green Growth" in 2010. G-SEED(Green Standard for Energy and Environmental Design) based on GBCS(Green Building Certification System) has been actively promoted for its application. This study has limited its scope to G-SEED office buildings. It has conducted surveys of problems and assessment items of the G-SEED identified in the preceding study by the AHP(Analytic hierarchy process) method. The purpose of this study is to conduct a comparison analysis of problems and ranking of evaluation items recognized in the survey and to be presented as reference materials for G-SEED system improvements at its next amendments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.9
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• pp.1083-1090
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• 2011

A steam generator poses many difficulties during the development of a sodium-cooled fast reactor because of the sodium-water-reaction problems. Until now, several types of steam generators have been developed, but the specifications of these generators differed in each country. Moreover, even if a country had developed a steam generator, it was not used in the subsequent reactor because the current techniques were not stabilized to select the proper steam generator. As a common development, the Benson steam cycle with few welding locations and high economical efficiency may be adopted. Moreover, the design is dwelled on the convenience of inspection, detection, control, and maintenance for the wear caused by sodiumwater reactions. The specifications of the designed steam generators were reviewed and the current technical problems for steam generators were analyzed. Concepts were proposed to overcome the current technical problems for steam generators.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.3
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• pp.277-283
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• 2006

A recently proposed method for stabilizing haptic interfaces and teleoperation systems was tested with a 'PHANToM' commercial haptic device. The 'Passivity Observer' (PO) and 'Passivity Control1er' (PC) stabilization method was applied to stabilize the system but also excited a high frequency mode in the device. To solve this problem, we propose a method to use a timevarying desired energy threshold instead of fixed zero energy threshold for the PO, and make the actual energy input follow the timevarying energy threshold. With the time-varying energy threshold, we make the PC control action smooth without sudden impulsive behavior by distributing the dissipation. The proposed new PO/PC approach is applied to PHANToM with high stiffness (K = 5000N/m), and stable and smooth contact is guaranteed. Resetting and active environment display problems also can be solved with the reference energy following idea.