• International conference on construction engineering and project management
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• 2024.07a
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• pp.1278-1278
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• 2024

Private Finance Initiative (PFI) involves long-term contracts where private entities invest in the construction and maintenance of street lighting facilities. The current implementation of PFI Smart Street Lighting Systems faces challenges in the fulfillment process, including discrepancies in quantities, coordination of power variations, delays in the deployment of smart systems, and issues with performance indicator scoring. These challenges disrupt the smooth execution of contractual obligations. Nevertheless, the adoption of intelligent systems in street lighting presents significant advantages in reducing energy consumption, extending the lifespan of fixtures, and enhancing maintenance efficiency. This study aims to analyze an ongoing project, applying the Fuzzy Analytic Hierarchy Process (FAHP) to identify crucial PFI indicators and their weights. The study explores areas of improvement in the project compared to traditional street lighting, aiming to provide solutions to the mentioned challenges. The results indicate that indicators such as PS3 (Lighting Service Continuity) with a weight of 0.384% and PS4 (Smooth Operation of the Smart Street Lightings Management System) with a weight of 0.274% have the highest impact on service performance. Additionally, the project involves replacing 162,000 streetlights, resulting in a yearly energy consumption reduction of approximately 70%, a decrease in monthly maintenance time from an average of 48 hours to 15 hours, and an expected reduction of 900,000 tons in carbon emissions during the project period. Value for Money (VfM) analysis suggests an annual reduction in government expenditures of NTD 66 million. This reveals that implementing PFI model is more advantageous than traditional street lighting procurement, as it allows the government to leverage contractor financing and alleviate the initial high costs of streetlight replacement, thereby reducing the overall costs of streetlight establishment and maintenance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2B
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• pp.130-137
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• 2012

In this paper, we propose core and edge router architectures with LPI(Low Power Idle) for reducing energy consumption in OBS networks. The proposed core router architecture is comprised of a BCP switch, a burst switch, line cards and sleep/wake controller for LPI. When the offered load of network is low, sleep/wake controller can change the state of the core router line card from active to sleep state for saving the energy after receiving network control packet. The edge router consists of a switch for access line card, a SCU and OBS edge router line cards. The LPI function in edge router line card is performed through network level control by network control packet, individually. Additionally, PHY/transceiver modules can transition active state to sleep state when burst assemble engine generates new bursts. To evaluate the energy saving performance of proposed architecture with LPI, the power consumption of each router is analyzed by using data sheet of commercial router and optical device. And, simulation is also performed in terms of sleep time of PHY/Transceiver through OPNET.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1383-1388
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• 2011

Due to many recent activities on enforcement of the intensified environmental regulation such as the policies of curbing the greenhouse gas and the Restriction of Hazardous Substances (RoHS), the usage of Light emitting diode (LED) has been rapidly increased and energy efficient management of LED light system is regarded as an important technology to enhance the energy efficiency. In this paper, we propose an energy-efficient control scheme of LED light, being composed of multiple light sources. The proposed scheme controls the intensity of LED light source to minimize the total intensity while providing the quality of lighting service. The intensity of light is assumed to be proportional to power consumption, thus the objective is to minimize the total power consumption. A linear programming problem is formulated to find the optimal intensity of each light source and procedure to apply the proposed scheme in the real system is suggested. The performance evaluation results elucidate that the proposed scheme achieves over 20% improvement in power consumption of light intensity in comparison with the conventional dimming control scheme.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.466-471
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• 2007

The purpose of study is to obtain basic but important information for the operation of the greenhouse facility located in the suburb of town. Special emphasis is given on the aspect of energy saving method, which can be easilyapplicable in a practical sense. For this end numerical calculation has been made systematically in order to increase the energy efficiency by the evaluation of the temperature distribution in greenhouse. Major parameters considered are primarily the overall shape of greenhouse together with the various conditions of baffle installion inside greenhouse. Further, the performance of heating system is also carefully compared each other for a number of typical arrangements of heating duct. The performance of the computer program developed in this study is evaluated by the observation of the famous fluid trapping phenomenon occurred in staggered baffle condition in the enclosure of greenhouse. Based on the this study, a number of useful conclusions can be drawn, that is, the installation of baffles are quite effective in energy saving method with a minor modification of facility. Also, it is found that the change of the heating duct system can contribute significantly to the uniform temperature distribution in greenhouse. Further other findings obtained by numerical calculation were not only physically consistent and meaningful but also useful for the determination of optimum condition of practical operation of greenhouse.

• Journal of Energy Engineering
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• v.29 no.2
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• pp.1-9
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• 2020

In recent days, fuel cell has received attention from the world as an alternative power source to hydrocarbon used in automobile engines. With the industrial advances of fuel cell, There have been a lot of researches actively conducted to find a way of generating hydrogen. Among many hydrogen production methods, Solid Oxide Electrolysis Cell(SOEC) is not only a basic way but also environment-friendly method to produce hydrogen gas. Solid Oxide Electrolysis Cell has lower electrical energy demands and high thermal efficiency since it is possible to operate under high temperature and high pressure conditions. For these reasons, experimental researches as well as studies on numerical modeling for Solid Oxide Electrolysis Cell have been under way. However, studies on numerical modeling are relatively less enough than experimental accomplishments and have limited performance prediction, which mostly is considered as a result from inadequate effects of electrochemical properties by temperature and pressure. In this study, various experimental studies of commercial Membrane Electrode Assembly (MEA) composed of Ni-YSZ (40wt%, Ni-60 wt% YSZ)/8-YSZ (TOSOH, TZ8Y)/LSM (La_0.9Sr_0.1MnO₃) was utilized for improving effectiveness of SOEC model. After numerically analyzing effects of electrochemical properties according to operating temperature, causing the largest deviation between experiments and simulation are that Charge Transfer Coefficient (CTC), exchange current density, diffusion coefficient, electrical conductivity in SOEC. Analyzing temperature effect on parameter used in overpotential model is conducted for modeling of SOEC. cross-validation method is adopted for application of various MEA and evaluating feasibility of model. As a result, the study confirm that the numerical model of SOEC based on structured process of effectiveness evaluation makes performance prediction better.

• Journal of the Korea Institute of Building Construction
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• v.10 no.2
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• pp.97-104
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• 2010

This study evaluated the energy efficiency of a windows system using built-in blinds, with regard to their insulation performance and their blocking of solar radiation. The study took advantage of the "Physibel Voltra" program as a physical simulation of heat transfer. To simulate the "Physibel Voltra" program, I practiced a mock-up test to determine heating quality and translation condition. I analyzed the propensity to annual energy consumption, the annual quantity of heat transfer, and the annual cooling and heating cost through a computer simulation for one general household in an apartment building. In the test, it was found that compared to a general windows system, a windows system with built-in blinds reduced the annual heat transfer by 10% in cooling states and by 11% in heating states when the blind was up. When the blind was down, the windows system with built-in blinds reduced the annual heat transfer by 25% in cooling states and 30% in heating states. When a windows system with built-in blinds is compared with a general windows system, the quantity of cooling and heating loads is reduced by 283.3kw in cooling states and 76.3kw in heating states. This leads to a reduction in the required cooling and heating energy of 359.6kw per house. It is thus judged that the use of a windows system with built-in blinds is advantageous in terms of reducing greenhouse gas emissions, because the annual TOE (tons of oil equivalent) per house is reduced by 0.078TOE, while $tCO_2$ is reduced by $0.16tCO_2$. In addition, compared with a general windows system, the cost of cooling and heating loads in the system reduces the annual cooling cost by 100,000won, and the annual heating cost by 50,000won. Ultimately, this means that cooling and heating loads are cut by 150,000won per year.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.31-36
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• 2011

BACKGROUND: Disposal of slurry animal manure produced by an anaerobic slurry-type barn method is not easy since the animal slurry contain high moisture content which makes solid-liquid separation a difficult process. However, recently, the interest about anaerobic digestion process as an environment-friendly waste disposal method has gained a wide interest because it can treat highly organic matter contained by the piggery slurry, decrease the odor after treatment, and enable the effective recovery of the methane gas which is a valuable energy resource. The objectives of this study were to identify the solubilization characteristics and to improve the anaerobic digestion efficiency of piggery slurry through full-scale anaerobic digestion experiments. METHODS AND RESULTS: In a full-scale continuous anaerobic digestion operation, the adaptability of single anaerobic digestion and its digestion efficiency were also evaluated in the farm field. The actual pH range and alkalinity concentration of piggery slurry used during the operation were comparatively higher than the concentrations of pH and alkalinity in the digestion tank which were stable at 7.5~8.0, 4,008 mg/L (as$CaCO_3$), respectively. The removal efficiency of organic matter (TCOD) by anaerobic digestion was 75~90% and methane gas production amount was at 0.33 L/L/day, a little higher than that of ordinary animal manure. CONCLUSION(s): Our findings showed higher recovery of highly purified methane and greater efficiency of anaerobic tank digestion since its methane gas content was at 65~70%.

• Journal of Aquaculture
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• v.9 no.4
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• pp.377-384
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• 1996

A 15-week of growth trial was conducted to evaluate practical diets for growing Korean rockfish (Sebastes schlegeli). Two replicate groups of the fish average weighing 125 g were fed one of four experimental diets containing $41\~45\%$ protein and $6\~8\%$ lipid. A control diet with $58\%$ fish meal as protein source was included and practical form diets with $40\%$ fish meal and various practical ingredients such as meat meal, blood meal, soybean meal, and corn gluten meal were included. These experimental dry pellet diets were compared with commercial diets containing $51\~53\%$ protein and $5\~13\%$ lipid for marine fish or raw fish-based moist pellet (RMP) diet containing $58\%$ protein and $9\%$ lipid consisted of $50\%$ frozen horse mackerel and $50\%$ commercial binder meal. Weight gain, feed efficiency, daily feed intake and protein efficiency ratio in the fish fed the experimental diets and commercial diets were not significantly different to those in the fish fed the control diet. However weight gain, feed efficiency and protein efficiency ratio in the fish fed the RMP diet were significantly higher than those in the fish fed the experimental diets and commercial diets. These differences of growth performance between experimental diets and RMP diet may be reason for different dietary protein and energy levels. The experimental diet can save up to $20\%$ cost of fish production compare with control diet, whereas RMP diet is more expensive than other diets in the fish production.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.316-322
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• 2006

The current study evaluated the technical feasibility of the application of $TiO_2$ photocatalysis for the removal of nocotine which has well known as a representative material of environmental tobacco smoke(ETS). Four different preliminary experiments were performed for the evaluation of nicotine removal using photocatalyst-coated construction materials. The photocatalytic removal of nicotine was investigated for five parameters: dry condition of coating tiles, type of coating sol, number of coatings, relative humidity(RH), and input concentrations. Prior to performing the parameter tests, adsorption of nicotine onto the current experimental system was surveyed. All the variables tested in the present study exhibited to influence the photocatalytic decomposition of Nicotine. A dry condition of high temperature and short dry period presented higher photocatalytic oxidation(PCO) efficiency compared to that of low temperature and long dry period. ST-KO3 sol showed higher decomposition efficiency than E-T Sol. The PCO efficiency increased as the number of coating increased. High humidity and low input concentrations exhibited higher PCO efficiency. Consequently, it is noted that the five parameters tested in the present study should be considered for the application of photocatalyst-coated construction materials in cleaning nicotine in ETS.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.868-873
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• 2019

In this study, the evaluation of performance of AORFB using methyl viologen and TEMPOL as organic active materials in neutral supporting electrolyte (NaCl) with various membrane types was performed. Using methyl viologen and TEMPOL as active materials in neutral electrolyte solution, the cell voltage is 1.37V which is relatively high value for AORFB. Two types of membranes were examined for performance comparison. First, when using Nafion 117 membrane which is commercial cation exchange membrane, only the charge process occurred in the first cycle and the single cell couldn't work because of its high resistance. However, when using Fumasep anion exchange membrane (FAA-3-50) instead of Nafion 117 membrane, the result was obtained as the totally different charge-discharge graphs. When current density was $40mA{\cdot}cm^{-2}$ and cut off voltage range was from 0.55 V to 1.7 V, the charge efficiency (CE) was 97% and voltage efficiency (VE) was 78%. In addition, the discharge capacity was $1.44Ah{\cdot}L^{-1}$ which was 54% of theoretical capacity ($2.68Ah{\cdot}L^{-1}$) at $10^{th}$ cycle and the capacity loss rate was $0.0015Ah{\cdot}L^{-1}$ per cycle during 50 cycles. Through cyclic voltammetry test, it seems that this difference in the performance between the full cell using Nafion 117 membrane and Fumasep anion exchange membrane came from increasing resistance due to chemical reaction between membrane and active material, not the capacity loss due to cross-over of active material through membrane.