• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.86-93
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• 2023

A bridge health monitoring technology is under development for the safety management of aged bridges. The bridge health monitoring technology has been developed mainly for single bridge management at a large scale, so it uses wire-based systems for power supply and data transfer. However, the wire-based systems need to be improved for the sporadically distributed small-sized bridges on local roads. This study proposed a wireless structural health monitoring system for small-sized bridges. The proposed monitoring system overcomes the limitations of wired systems by providing wireless power through solar power and utilizing LTE technology to transmit measurement data. In addition, a remote control system and power management plan were proposed to ensure the stability of the bridge measurement system. The proposed measurement system was installed on 32 bridges on fields and verified the operability by collecting 80.6% of measurement data for one year. The proposed system can support the health monitoring of aged bridges on local roads.

• Journal of Korean Society of Disaster and Security
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• v.16 no.4
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• pp.147-156
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• 2023

Because the behavior of cable bridges is dominated by dynamic response and is relatively complex, short- and long-term field monitoring are often required to evaluate the bridge condition. If a permanent SHMS (Structural Health Monitoring System) is not installed, a portable monitoring system is needed for the checking of bridge condition. In this case, it can be difficult to operate the portable monitoring system due to limited conditions such as power and communication according to the location and type of the bridge. In this study, the portable-based smart structural response monitoring system is developed that can be effectively used for short- and long-term monitoring of cable bridges in Korea and Southeast Asia. The developed system is a multi-channel portable data acquisition and analyzer that can be operated for a long time in the field using its own power supply system, and is included with the automated analysis algorithm for the dynamic characteristics of cable bridges using real-time data. In order to evaluate the field applicability of the developed system, field demonstration was conducted on cable bridges in Korea and Vietnam. Through the demonstration, the reliability and efficiency of field operation of the developed system were confirmed, and additionally, the possibility of application to overseas markets was confirmed in cable bridge monitoring field.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.717-729
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• 2005

Peak cooling load of large buildings is generally greater than their peak heating load. Internal and solar heat gains are used fur selection of adquate equipment in large building in cold winter climate like Canada and even Korea. The cost of geothermal heat exchanger to meet the cooling loads can increase the initial cost of ground source heat pump system to the extend less costly conventional system often chosen. Thermal ice storage system has been used for many years in Korea to reduce chiller capacity and shift Peak electrical time and demand. A distribution system designed to take advantage of heat extracted from the ice, and use of geothermal loop (geothermal heat exchanger) to heat as an alternate heat source and sink is well known to provide many benifits. The use of thermal energy storage (TES) reduces the heat pump capacity and peak cooling load needed in large building by as much as 40 to $60\%$ with less mechanical equipment and less space for mechanical room. Additionally TES can reduce the size and cost of the geothermal loop by 1/3 to 1/4 compared to ground coupled heat pump system that is designed to meet the peak heating and cooling load and also can eliminate difficuties of geothermal loop installation such as space requirements and thermal conditions of soil and rock at the urban area.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.599-604
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• 1998

We have investigated Pt and $RuO_2$ as a bottom electrode for ferroelectric capacitor applications. The bottom electrodes were prepared by using an RF magnetron sputtering method. Some of the investigated parameters were a substrate temperature, gas flow rate, RF power for the film growth, and post annealing effect. The substrate temperature strongly influenced the surface morphology and resistivity of the bottom electrodes as well as the film crystallographic structure. XRD results on Pt films showed a mixed phase of (111) and (200) peak for the substrate temperature ranged from RT to $200^{\circ}C$, and a preferred (111) orientation for $300^{\circ}C$. From the XRD and AFM results, we recommend the substrate temperature of $300^{\circ}C$ and RF power 80W for the Pt bottom electrode growth. With the variation of an oxygen partial pressure from 0 to 50%, we learned that only Ru metal was grown with 0~5% of $O_2$ gas, mixed phase of Ru and $RuO_2$ for $O_ 2$ partial pressure between 10~40%, and a pure $RuO_2$ phase with $O_2$ partial pressure of 50%. This result indicates that a double layer of $RuO_2/Ru$ can be grown in a process with the modulation of gas flow rate. Double layer structure is expected to reduce the fatigue problem while keeping a low electrical resistivity. As post anneal temperature was increased from RT to $700^{\circ}C$, the resistivity of Pt and $RuO_2$ was decreased linearly. This paper presents the optimized process conditions of the bottom electrodes for memory device applications.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.324-332
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• 2017

The comparative experiments were conducted for single span greenhouses where cucumbers were cultivated to analyze the effect of heating between a carbon fiber electric heating element heater and an oil hot air heater in terms of the inside climate, energy consumption and plant growth. In order to analyze the effect of heating capacity, 6, 9, and 16 kW of electric powers were supplied to the electric heating element for same setting temperature of 15?. As a result, as the heating capacity increased, the number of ON-OFF cycles of the electric heating element and the temperature inside the greenhouse increased proportionally. In the comparison of two heaters, it was shown that the temperature and relative humidity distributions of the electric heating element installed greenhouse was much uniform than those of the oil hot air heater installed greenhouse. The heating energy consumptions during the heating period of 79 days were 867L for the oil hot air heater and 8,959 kWh for the electric heating element heater, and the heating costs were 607 and 403 thousand won respectively. In the electric heating element installed greenhouse, the cucumber growth was slightly better and the yield was 4.3% higher than those of the oil hot air heater installed greenhouse, but there were no statically significant difference in the cucumber growth and yield between greenhouses.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.9
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• pp.14-23
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• 2010

This paper reports the fabrication of a DVB-T/H System in Package (SiP) that is able to receive and process the DVB-T/H signal. The DVB-T/H is the European telecommunication standard for Digital Video Broadcasting (DVB). An IC-embedded Printed Circuit Board (PCB) process, interpose a chip between PCB layers, has applied to the DVB-T/H SiP. The chip inserted in DVB-T/H SiP is the System on Chip (SoC) for mobile TV. It is comprised of a RF block for DVB-T/H RF signal and a digital block to convert received signal to digital signal for an application processor. To operate the DVB-T/H IC, a 3MHz DC-DC converter and LDO are on the DVB-T/H SiP. And a 38.4MHz crystal is used as a clock source. The fabricated DVB-T/H SiP form 4 layers which size is $8mm{\times}8mm$. The DVB-T/H IC is located between 2nd and 3rd layer. According to the result of simulation, the RF signal sensitivity is improved since the layout modification of the ground plane and via. And we confirmed the adjustment of LC value on power transmission is necessary to turn down the noise level in a SiP. Although the size of a DVB-T/H SiP is decreased over 70% than reference module, the power consumption and efficiency is on a par with reference module. The average power consumption is 297mW and the efficiency is 87%. But, the RF signal sensitivity is declined by average 3.8dB. This is caused by the decrease of the RF signal sensitivity which is 2.8dB, because of the noise from the DC-DC converter.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.61-72
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• 2014

This paper analyzed transition pathways toward a low carbon society in Korea to meet global $2^{\circ}C$ climate target. Lower economic growth, industrial structure change, enhance of energy demand management, decarbonization of power sector, and replacement of low carbon fuel could reduce greenhouse gas (GHG) emission from fuel combustion in 2050 by 67% against in 2011, or by 74% against in BAU (Business-As-Usual). Lower economic growth contributes to 13% of cumulative emission reduction relative to BAU, industrial structure change 9%, enhance of energy demand management 72%, decarbonization of power sector 5% and replacement of low carbon fuel 1% respectively. Final energy consumption in 2050 needs to be reduced to 50% relative to 2011, or to 41% relative to BAU. Nuclear, coal and renewable energy represent 31%, 40%, 2% respectively among electricity generation in 2011, but 38%, 2%, 32% in 2050. CCS represents 23% of total generation in 2050. Emission intensity of electricity in 2050 was decreased to 19% relative to 2011, or to 24% relative to BAU. Primary energy in 2050 was decreased to 64% compared to 2011, or to 44% compared to BAU. Final energy consumption, primary energy supply and GHG emission from fuel combustion from 1990 to 2011 increased by 176%, 197%, 146%. Radical change from historical trend is required to transit toward a low carbon society by 2050. Appropriate economic growth, structural change to non-energy intensive industries, energy technology research, development and deployment (RD&D) in terms of enhancement of energy efficiency and low carbon energy supply technologies, and fuel change to electricity and renewable energy are key instruments.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.1
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• pp.9-18
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• 2012

Annual power consumption of our country is positioned in the upper percentile in the world, and because the proportion of fossil power generation is high, which ranks the 10th $CO_2$ emission country. In this regard, government has established and is implementing the National Energy Basic Plan to realize to get out of fossilization in energy supply while focusing on securing the technology for renewable energy as well as its commercialization in order to reduce greenhouse gas. Resource recovery technology for deep seawater thermal energy which is one of renewable energies is newly getting attention domestically as well as in overseas for securing resources and environmental improvement as a core technology for multilateral use of marine resources for low carbon and green growth. Economic feasibility analysis was conducted for the research and development as follows on the use of ocean thermal energy conversion and seawater air conditioning. First, in the case of power generation using deep seawater and warm discharge water from ocean thermal energy conversion plant of 1MW level, it is judged that the economic feasibility is insufficient but the feasibility will be significantly improved if we consider not only power generation but also drinking water and certified emission reduction by developing the power plant to the size for commercialization. Second, the economic feasibility for the use of deep seawater as air conditioning for the power plant of 1,000RT level turned out to be very good. Especially, when we consider certified emission reduction, it will be possible to secure sufficient economic feasibility. When we use it in connection with ocean thermal energy conversion, water conversion and agricultural and fishery use, it is judged that economic ripple effect will be significant and therefore it will be necessary to conduct research and development for early commercialization, distribution and diffusion of deep seawater energy.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.461-466
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• 2010

In this study the feasibility of simultaneous electricity generation and treatment of swine farm wastewater using microbial fuel cells (MFCs) was examined. Two single-chamber MFCs containing an anode filled with different ratio of graphite felt and stainless-steel cross strip was used in all tests. The proportion of stainless-steel cross strip to graphite felt in the anode of control microbial fuel cell (CMFC) was higher than that of swine microbial fuel cell (SMFC) to reduce construction costs. SMFCs produced a stable current of 18 mA by swine wastewater with chemical oxygen demand (COD) of $3.167{\pm}80\;mg/L$ after enriched. The maximum power density and current density of SMFCs were $680\;mW/m^3$ and $3,770\;mA/m^3$, respectively. In the CMFC, power density and current density was lower than that of SMFC. CODs decreased by the SMFC and CMFC from $3.167{\pm}80$ to $865{\pm}21$ and $930{\pm}14\;mg/L$, achieving 72.7% and 70.6% COD removal, respectively. The suspended solid (SS) of both fuel cells was also reduced over 99% ($4,533{\pm}67$ to $24.0{\pm}6.0\;mg/L$). The concentration of nutritive salts, ${NH_4}^+$, ${NO_3}^-$, and ${PO_4}^{3-}$, dropped by 65.4%, 57.5%, and 73.7% by the SMFC, respectively. These results were similar with those of CMFC. These results show that the microbial fuel cells using electrode with mix stainless-steel cross strip and graphite felt can treat the swine wastewater simultaneously with an electricity generation from swine wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.7
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• pp.459-466
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• 2012

In order to improved treatment performance of dielectric barrier discharge (DBD) plasma, plasm + UV process and gas-liquid mixing method has been investigated. This study investigated the degradation of N, N-Dimethyl-4-nitrosoaniline (RNO, indicator of the generation of OH radical). The basic DBD plasma reactor of this study consisted of a plasma reactor (consist of quartz dielectric tube, titanium discharge (inner) and ground (outer) electrode), air and power supply system. Improvement of plasma reactor was done by the combined basic plasma reactor with the UV process, adapt of gas-liquid mixer. The effect of UV power of plasma + UV process (0~10 W), gas-liquid mixing existence and type of mixer, air flow rate (1~6 L/min), range of diffuser pore size (16~$160{\mu}m$), water circulation rate (2.8~9.4 L/min) and UV power of improved plasma + UV process (0~10 W) were evaluated. The experimental results showed that RNO degradation of optimum plasma + UV process was 7.36% higher than that of the basic plasma reactor. It was observed that the RNO decomposition of gas-liquid mixing method was higher than that of the plasma + UV process. Performance for RNO degradation with gas-liquid mixing method lie in: gas-liquid mixing type > pump type > basic reactor. RNO degradation of improved reactor which is adapted gas-liquid mixer of diffuser type showed increase of 17.42% removal efficiency. The optimum air flow rate, range of diffuser pore size and water circulation rate for the RNO degradation at improved reactor system were 4 L/min, 40~$100{\mu}m$ and 6.9 L/min, respectively. Synergistic effect of gas-liquid mixing plasma + UV process was found to be insignificant.