• Journal of Korean Society of Water and Wastewater
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• v.25 no.4
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• pp.573-579
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• 2011

As rapid advances in technologies continue, seawater reverse osmosis (SWRO) desalination systems are now more energy-efficient than conventional thermal processes. Some SWRO desalination plants can achieve the specific energy consumption (SEC) below 2 kWh/$m^3$. Along with the development of new membranes and high-performance pumps, energy recovery devices (ERD), which recover the hydraulic energy of brine, have been developed to enhance energy efficiency. In this work, we reviewed general aspects of ERD technologies and their market trends. The advantages and disadvantages of various EDR technologies were compared to explore the future directions of ERD development.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.11
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• pp.557-562
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• 2003

To develop a stable and compact small-sized superconducting magnetic energy storage (SMES) system, which provides electric power with high quality to sensitive electric loads, we fabricated a SMES coil and tested it. Because such a large-sized superconducting coil quenches far away from its critical current, the recovery current is frequently used as a stability criterion in the coil fabrication. Therefore, we first investigated the recovery current characteristics of the large current conductor, which was used in our SMES coil fabrication. The test results indicate that the recovery currents measured in the conductor are nearly identical to those based on the single wire. This implies that the recovery current is affected by the conductor's cooling condition rather than its size and current capacity. In the SMES coil test the first quench occurred at 1250 A, which is equivalent to the stored energy of about 2 MJ. It corresponds to the quench current density of about $130A/mm^2$ This value is much higher in comparison with that reported in the other work. In addition, the first quench current of the coil agrees well with the measured recovery current of the conductor having similar cooling condition with it. This means that to determine the recovery current of a conductor is, first of all, important in the design and fabrication of a large-sized superconducting coil.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.239-242
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• 2005

A high speed address recovery technique for AC plasma display Panel(PDP) is proposed. By removing the GND switching operation, the recovery speed can be increased and switching loss due to GND switch also becomes to be reduced. The proposed method is able to perform load-adaptive operation by controlling the voltage level of energy recovery capacitor, which prevents increasing inefficient power consumption caused by circuit loss during recovery operation. Thus, the technique shows the minimum address power consumption according to various displayed images, different from Prior methods operating in fixed mode regardless of images. Test results with 50" HD single-scan PDP(resolution = 1366$\times$768) show that less than 350ns of recovery time is successfully accomplished and about 54% of the maximum power consumption can be reduced, tracing minimum power consumption curves.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.9
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• pp.450-453
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• 2005

A high speed address recovery technique for AC plasma display panel(PDP) is proposed. Replacing GND switch by clamping diode. the recovery speed can be increased by saving GND hold-time and switching loss due to GND switch also becomes also be reduced. The proposed method is able to perform load-adaptive operation by controlling the voltage level of energy recovery capacitor, which prevents increasing inefficient power consumption caused by circuit loss during recovery operation. Test results with 50' HD single-scan PDP(resolution = 1366$\times$768) show that less than 3sons of recovery time is successfully accomplished and about$54\%$ of the maximum power consumption can be reduced, tracing minimum power consumption curves.

• KIEAE Journal
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• v.15 no.4
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• pp.77-84
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• 2015

Purpose: In 2008, As the green growth policy was presented, Green Building is made any effort to propagation. In this paper, the respective technologies that are able to considerably reduce the energy demands for heating, cooling, hot-water, lighting and ventilation among the variety of technologies were selected. Method: Design factors such as (1) External insulation, (2) Triple glazing window, (3) LED lighting, (4) External venetian blind, (5) Geothermal and (6) Heat recovery ventilator were derived. In addition, energy saving effects in terms of energy demand, energy consumption and energy cost were investigated using EnergyPlus, building energy analysis tool. Result : The results were as follows. (1) It can be seen that high insulated triple glazing window, heat recovery ventilator and external insulation technology is excellent for energy demand. (2) Unlike energy demand, saving effect of energy consumption and energy cost was shown in order of Geothermal > Triple Window > Heat recovery Ventilation> Insulation> LED Lighting > EVB Blind.

• Journal of Korean Society on Water Environment
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• v.34 no.1
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• pp.121-131
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• 2018

Domestic sewage treatment plants (STPs) consume about 0.5 % of total electric energy produced annually, which is equivalent to 207.7 billion Korean won per year. To minimize the energy consumption and as a way of mitigating the depletion of energy sources, the sewage treatment strategy should be improved to the level of "energy positive". The core processes for the energy positive sewage treatment include A-stage for energy recovery and B-stage for energy-efficient nitrogen removal. The integrated process is known as the A/B-process. In A-stage, chemically enhanced primary treatment (CEPT) or high rate activated sludge (HRAS) processes can be utilized by modifying the primary settling in the first stage of sewage treatment. CEPT utilizes chemical coagulation and flocculation, while HRAS applies returned activated sludge for the efficient recovery of organic contents. The two processes showed organic recovery efficiencies ranging from 60 to 70 %. At a given recovery efficiency of 80 %, 17.3 % of energy potential ($1,398kJ/m^3$) is recovered through the anaerobic digestion and combustion of methane. Besides, anaerobic membrane bioreactor (AnMBR) can recover 85% of organic contents and generate $1,580kJ/m^3$ from the sewage. The recovered energy is equal to the amount of energy consumption by sewage treatment equipped with anaerobic ammonium oxidation (ANAMMOX)-based B-stage, $810{\sim}1,620kJ/m^3$. Therefore, it is possible to upgrade STPs as efficient as energy neutral. However, additional novel technologies, such as, fuel cell and co-digestion, should be applied to achieve "energy positive" sewage treatment.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.327-332
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• 1999

The recovery activation energy, the order of reaction and the recovery rate constant were detemined by isochronal and isothermal annealing treatment to investigate the recovery behaviors of neutron irradiated Mn-Mo-Ni low alloy steels$(fluence: 2.3\times10^{19}ncm^{-2}, 553K, E\geq1.0 MeV)$. Vickers microhardness tests were conducted to trace the recovery behavior after heat treatments. The results were analyzed in terms of recovery stages, behavior of responsible defects and recovery kinetics. It was shown that recovery occurred through two annealing stages(stage I : 703-753K, stage n : 813-873K) with re$\infty$very activation energies of 2.5 eV and 2.93 eV for each stage I and n, respectively. From the comparison of unirradiated and irradiated isochronal anneal curves, a radiation anneal hardening(RAH) peak was identified at around 813K. Most of recovery have occurred during about 120 min irrespective of isothermal annealing temperatures of 743K and 833K. Recovery rate constants were determined to be $3.4\times10^{-4}min^{-1} and 7.1\times10^{-4}min^{-1}$ for stage I and II, respectively. The order of reaction was about 2 for both recovery stages. Comparing the obtained data with those of previously reported results on neutron irradiated Mn- Mo- Ni steels, the thermal recovery be­havior of the present material seems to occur by the dissociation of point defect clusters formed during irradiation, and by the recombination process of self-interstitials and vacancies from dissociated vacancy clusters.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.116-125
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• 2010

In this study, a novel hydraulic energy-regenerative system was presented from its proposal through its modeling to its control. The system was based on a closed-loop hydrostatic transmission and used a hydraulic accumulator as the energy storage system in a novel configuration to recover the kinetic energy without any reversion of the fluid flow. The displacement variation in the secondary unit was reduced, which widened the uses of several types of hydraulic pump/motors for the secondary unit. The proposed system was modeled based on its physical attributes. Simulation and experiments were performed to evaluate the validity of the employed mathematical model and the energy recovery potential of the system. The experimental results indicated that the round trip recovery efficiency varied from 22% to 59% for the test bench.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.12
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• pp.1057-1065
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• 2000

A sizing of sensible and latent energy recovery system with condensing heat exchanger is important to the design of a thermally controlled facilities. The transient system simulation program TRNSYS 14.2/IISiBat has been used to evaluate the energy consumptions of a thermally controlled facilities which consist of boiler, chiller and condensing heat exchanger, The boiler and chiller are selected based on the annual peak loads and controlled to maintain the setting temperature of $14~17^{\circ}C$. Simulation shows that the amount of sensible and latent energy recovered by heat exchanger is almost 20% of total heating load.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.844-849
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• 2008

In recent semiconductor manufacturing clean rooms, in order to improve clean room air quality, air washers are used to remove airborne gaseous contaminants such as $NH_3$, SOx and organic gases from outdoor air introduced into clean room. Meanwhile, there is a large quantity of exhaust air from clean room. From the energy saving point of view, heat recovery is useful for the reduction of air conditioning energy consumption for clean room. Therefore it is desirable to recover heat from the exhaust air and use it to reheat the outdoor air. However, so far there have not been sufficient studies of analyzing the comparison of the amounts of energy consumption and saving. In the present study, an experiment was conducted to investigate the energy consumption and heat recovery of a fin-coil type air washer system for semiconductor manufacturing clean rooms.