• Journal of Navigation and Port Research
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• v.47 no.2
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• pp.106-119
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• 2023

Due to global decarbonization movement and tightening of maritime emissions restrictions, the shipping industry is going to switch to alternative fuels. Among candidates of alternative fuel, methanol is promising for decreasing SOx and CO2 emissions, resulting in minimum climate change and meeting the goal of green shipping. In this study, a novel combined system of direct methanol solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC), gas turbine (GT), and organic Rankine cycle (ORC) targeted for marine vessels was proposed. The SOFC is the main power generator of the system, whereas the GT and PEMFC could recover waste heat from the SOFC to generate useful power and increase waste heat utilizing efficiency of the system. Thermodynamics model of the combined system and each component were established and analyzed. Energy and exergy efficiencies of subsystems and the entire system were estimated with participation of the first and second laws of thermodynamics. The energy and exergy efficiencies of the overall multigeneration system were estimated to be 76.2% and 30.3%, respectively. The combination of GT and PEMFC increased the energy efficiency by 18.91% compared to the SOFC stand-alone system. By changing the methanol distribution ratio from 0.05 to 0.4, energy and exergy efficiencies decreased by 15.49% and 5.41%, respectively. During the starting up and maneuvering period of vessels, a quick response from the power supply system and propulsion plant is necessary. Utilization of PEMFC coupled with SOFC has remarkable meaning and benefits.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.953-965
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• 2023

The stratospheric drones are developed to perform missions such as weather observation, communication relay, surveillance, and reconnaissance at 18km to 20km, where climate change is minimal and there is no worry about a collision with aircraft. It uses solar panels for daytime flights and energy stored in batteries for night flights, providing many advantages over existing satellites. The electrical and power systems essential for stratospheric drone flight must ensure reliability, efficiency, and lightness by selecting the optimal circuit topology. Therefore, it is necessary to analyze the circuit topology of various types of multi-level inverters with high redundancy that can ensure the reliability and efficiency of the motor driving power required for stable long-term flight of stratospheric drones. By quantifying the switch element voltage drop and the number and weight of inverter components for each topology, we evaluate efficiency and lightness and propose the most suitable circuit topology for stratospheric drones.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.1
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• pp.81-89
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• 2017

In this paper, we propose a gait pattern recognition method for intelligent prosthesis that enables walking in various environments of femoral amputees. The proposed gait mode changing method is a single sensor based algorithm which can discriminate gait surface and gait phase using only strain gauges sensor, and it is designed to simplify the algorithm based on multiple sensors of existing intelligent prosthesis and to reduce cost of prosthesis system. For the recognition algorithm, we analyzed characteristics of the ground reaction force generated during gait of normal person and defined gait step segmentation and gait detection condition, A gait analyzer was constructed for the gait experiment in the environment similar to the femoral amputee. The validity of the paper was verified through the defined detection conditions and fabricated instruments. The accuracy of the algorithm based on the single sensor was 95%. Based on the proposed single sensor-based algorithm, it is considered that the intelligent prosthesis system can be made inexpensive, and the user can directly grasp the state of the walking surface and shift the walking mode. It is confirmed that it is possible to change the automatic walking mode to switch the walking mode that is suitable for the walking mode.

• Journal of Environmental Policy
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• v.13 no.2
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• pp.99-129
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• 2014

This research estimates the impact of population aging on energy use and carbon emissions by energy sources and by industrial sectors in Korea until 2035. For the estimation, the structural change in household consumption expenditure identified by the age-specific consumption pattern was analyzed in conjunction with energy and environment input-output tables. The estimation result presents that, despite the population aging, energy use and carbon emissions induced by household consumption continue to increase until 2026, and then that elevated levels of energy use and carbon emissions will be maintained for a considerable period of time. According to the estimation by energy sources, the use of natural gas will show substantial increase while the use of crude oil will switch to a downturn at a relatively early period. According to the estimation by industrial sectors, carbon emissions in the sectors with relatively high consumption share of old households such as medical health, dwelling, lighting, heating, air-conditioning, and food will have substantial increase, whereas those in the sectors associated with education, transport, catering, and accommodation services will turn downward relatively early. In addition, the study analyzes through policy simulation the impact of aging-related policy similar to the basic pension system, which is recently being discussed for legislation, on energy use and carbon emissions.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.288-295
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• 2018

Purpose: The paper aims to compare the effectiveness of the two types of transport demand management measures, namely pull measures and push measures. Method: Case studies of two metropolitan areas in the developing world assess the extent to which increases in fuel prices can contribute to reducing automobile use and increasing the public transport use and the potential of urban rail transit to cause mode shift from automobiles. Within the case studies, a stated response survey of current car users has been conducted for Cairo and an on-line survey of rail transit users in Algiers. Results: There was a major proportion of car drivers who intend to switch to public transport, depending on the range of fuel prices in Cairo and a considerable proportion of rail users who have switched from automobiles resulting in a measurable reduction in CO2 emissions in Algiers. Conclusion: Investments in urban rail can be highly effective where there are demands for better public transport, but this type of pull measures can be much more effective if combined with push measures which significantly raise driving costs.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.1
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• pp.25-32
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• 2019

K-BEMS System was introduced to reduce peak load and to save total energy of the 200 buildings that KEPCO headquarter and branch offices use. And K-BEMS system is composed of PV, battery, and hybrid PCS. KEPCO research institute has carried out this K-BEMS research project for 3 years since January 2016. In this paper, the results of the project are shown. 9 modes of test results of K-BEMS system and are operational problems were analyzed. And measures to cure the trouble are also suggested. Batteries are operated more than 20% of SOC, and less than 20% of SOC battery protection switches are automatically shutting down the system and the system no longer respond to EMS, ending the supply of PV, and so therefore to continue the PV power supply it was turn out to be necessary that the EMS should automatically change its policy to change PV only supply mode automatically when the Battery Switch automatically operated. To operate the system continuously and automatically, it is necessary to modify the minimum operational SOC value, and in addition to that the EMS computer must remember the last shut-down SOC and Voltage which interrupted the system and add some margin to reflect the measurement error in the system.

• The Journal of Sustainable Design and Educational Environment Research
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• v.21 no.4
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• pp.21-28
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• 2022

This study analyzes the reality of the overall operating system, such as recognition and satisfaction with school field support work system of the Education Facilities Management Center, recognition level of restructuring of work areas, and the direction of improvement for school facility maintenance support in various types of future learning environments. To analyze the problem of this study, a survey was conducted on 290 education administrative officials in Gyeonggi-do. First, school site awareness and work performance satisfaction of the Educational Facilities Management Center were evaluated as "below average," and it is necessary to improve the qualitative work area that is practically helpful to schools. Second, in the area of organizational operation, it is desirable to avoid simple tasks with a low evaluation of "below average" and to switch to an operating system that improves efficiency. Third, the need for the facility environment area (professionalism, safety) was the highest, but the center's ability and work processing level were evaluated very low as "below average," so it is urgent to improve the center's capacity. Fourth, in the area of social and educational policy change, the center received a high score for the need for access from the perspective of a learning environment linked to future education. Therefore, a policy review on the restructuring and improvement of work areas suitable for this is necessary.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.2
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• pp.70-80
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• 2011

Estuarine ecosystem responds sensitively to natural and anthropogenic perturbations. lt is necessary to identify the direction of the change when the perturbation occurs as well as to understand the structure and functioning of estuarine ecosystem for a proper management of the area. In this study, the estuarine habitats were classified into different ecological districts so as to the switch from one district to another district could be related to the environmental change due to the perturbations. Total 16 ecological districts was defined according to the presence of barrage, salinity and vegetation characteristics. The defined ecological districts were applied to small estuaries in Goseong bay, south sea of Korea (Baedun, Guman, Maam, Goseong) to distinguish different regions which might have characteristic bottom topography, inclinations of river bottom, sediment characteristics, salinity structure and area of vegetation. Total 7 out of 16 ecological district was identified in this region; NFB (natural, fresh, bare), NHB (natural, high salinity, bare), NLV (natural, low salinity, vegetated) in natural (without barrage) estuaries and CFB (closed, fresh, bare), CFV( closed, fresh vegetated), CLV (closed, low salinity, vegetated), CHB (closed, high salinity, bare) in closed (with barrage) estuary. A comparison of environmental factors and biota between CHB and CLV demonstrated the effect of barrage on estuarine ecosystem. The height and sediment characteristics of CHB and CLV were similar but the average salinity was lower in CLV than in CHB due to the barrage, which produced favorable condition for the Phragmites australis in CLV. Information regarding the ecological districts in various sizes and location could be useful for predicting the ecosystem change due to natural and anthropogenic perturbations and for preparing management actions.

• Journal of Life Science
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• v.20 no.12
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• pp.1777-1783
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• 2010

Plants generate reactive oxygen species (ROS) as a by-product of normal aerobic metabolism or when exposed to a variety of stress conditions, which can cause widespread damage to biological macromolecules. To protect themselves from oxidative stress, plant cells are equipped with a wide range of antioxidant proteins. However, the detailed reaction mechanisms of these are still unknown. Peroxiredoxins (Prxs) are ubiquitous thiol-containing antioxidants that reduce hydrogen peroxide with an N-terminal cysteine. The active-site cysteine of peroxiredoxins is selectively oxidized to cysteine sulfinic acid during catalysis, which leads to inactivation of peroxidase activity. This oxidation was thought to be irreversible. Recently identified small protein sulphiredoxin (Srx1), which is conserved in higher eukaryotes, reduces cysteine.sulphinic acid in yeast peroxiredoxin. Srx1 is highly induced by $H_2O_2$-treatment and the deletion of its gene causes decreased yeast tolerance to $H_2O_2$, which suggest its involvement in the metabolism of oxidants. Moreover, Srx1 is required for heat shock and oxidative stress induced functional, as well as conformational switch of yeast cytosolic peroxiredoxins. This change enhances protein stability and peroxidase activity, indicating that Srx1 plays a crucial role in peroxiredoxin stability and its regulation mechanism. Thus, the understanding of the molecular basis of Srx1 and its regulation is critical for revealing the mechanism of peroxiredoxin action. We postulate here that Srx1 is involved in dealing with oxidative stress via controlling peroxiredoxin recycling in Arabidopsis. This review article thus will be describing the functions of Prxs and Srx in Arabidopsis thaliana. There will be a special focus on the possible role of Srx1 in interacting with and reducing hyperoxidized Cys-sulphenic acid of Prxs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.391-399
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• 2020

KASI (Korea Astronomy and Space Science Institute) has been developing the multipurpose laser tracking system with three functions of satellite laser tracking, adaptive optics and space debris laser tracking for scientific research and national space missions. The space debris laser tracking system provides the distance to space debris without a laser retro-reflector array by using a high power pulse laser, which employs a spinning disk to change the optical path between the transmit and receive beams. The spinning disk causes the collision band which is unable to reflect the returned signal to a detector and then has an effect on the tracking coverage of space debris. This study proposed the mathematical model for tracking coverage by taking into account the various specifications of spinning disk such as disk size, spinning velocity and collision rate between the disk and hole. In addition, the spinning disk specifications were analyzed in terms of tracking coverage and collision band based on the mathematical model to investigate tracking requirements of the Geochang laser tracking system.