• Journal of Power Electronics
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• v.1 no.2
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• pp.99-106
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• 2001

This paper describes the implementation of a Storage Power Flow Controller (SPFC) connected to the grid which can provide concomitant benefits associated with a Unified Power Flow Controller while at the same time providing several other very important benefits to power system operation such as, load leveling dynamic voltage stability inprovement, harmonic compensation and power factor correction. This Storage power Flow Controller (SPFC) was implemented using real time signal processors, three-phase inverter(s) and battery bank which can provide improved power system operation and control, added system security and reduced power system losses.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1091-1093
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• 1998

The BESS has a major advantages such as load leveling, quick response emergency power (spinning reserve), frequency and voltage control, improvement of reliability, and deferred generation and transmission capacity construction. However, the economic feasibility of these systems requires justification from the customer side of meter. In this paper, we proposed the economic evaluation model of BESS which is modified and complemented the SYSPLAN model[2]. In addition, we analyzed a economic evaluation from the economic measures such as payback period, overall benefit, ROI, and ROR.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.584-589
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• 2008

It is known that slab thermal storage which uses concrete slab as thermal material is effective in the load leveling and using the nighttime electric power. The temperature distribution is not constant in plenum in thermal storage time by beams, ducts such as several factor. It is considered that this fact will effect on efficiency of thermal storage and indoor thermal environment. The purpose of this paper is to examine the thermal environment inside plenum. A macro model was made for the analysis of indoor thermal environment as the first step. The flow rate distribution and temperature distribution of object room model was examined by use of basic equations such as airflow by the pressure difference between unit cells, heat flow by air and heat transfer.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.202-204
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• 1993

Appropriate control of real and reactive power flowing in and out from system can lead to considerable benefits : network stabilization, load leveling, voltage regulation etc. This paper presents how to control real and reactive power flow between an flywheel energy storage system and a power three phase network. The system compensating real and reactive power consists of control system and cycloconverter operating in the four quadrant modes.

• Tribology and Lubricants
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• v.36 no.1
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• pp.27-33
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• 2020

Self-equalizing tilting pad thrust bearings are usually employed in turbomachines to achieve high stability and reliability. A tilting pad bearing can incorporate self-equalizing links to handle the misalignment between the bearing and the thrust collar. In this popular design method, the pads sit on the upper-level plates and the lower-level plates stay on the retainer base. With misalignment, the pads that are heavily loaded are pushed down. Consequently, the link pushes up the pads on the opposite side, keeping the bearing surface parallel to the thrust collar surface. The self-equalizing link is used to handle the misalignment from the thermal and mechanical effects. In this study, the experimental investigation deals with the performance of self-equalizing tilting pad thrust bearings. The test rig for evaluating the performance of bearing is developed which can control the misalignment angle. Simultaneous measurements are taken for the force acting on each pad. Pad metal temperature and oil film thickness are functions of the shaft speed, bearing load, misalignment angle, and design of leveling plates. The effect of misalignment on bearing performance is discussed. The results demonstrate that the load on each pad depends on the test conditions(especially misalignment angle), and the load influences the performance of bearings.

• Journal of the Korean Solar Energy Society
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• v.32 no.5
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• pp.52-58
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• 2012

Experimental study was performed to understand the real operation conditions of a showcase working usually in a convenient store and discount store. The purpose of this study was to show the possibility for practical use of cold-heat storage systems being operated for the showcase. To do that, evaporator and condenser temperatures were measured and the compressor electric power consumption were measured simultaneously. To use the ice storage system, the ice making process was typically operated during midnight being not needed the cooling of the showcase through the continuous running of the condenser unit. And then, the refrigerant was subcooled using the stored cold-heat after being discharged from the condenser during daytime. So, the cooling performance was increased with the sub-cooling of refrigerant during daytime,hence the actual running time of the compressor could be effectively decreased. Through the experiments, this study showed that the compressor electric power consumption during daytime could be transferred to nighttime for applying the refrigerant sub-cooling. So, for the convenient store, the maximum load transfer rates for each working cooler and showcase were estimated about 31.1% and 19.9% respectively. And for the discount store, the maximum load transfer rates for each refrigeration and freezing showcase were estimated about 34.1% and 49.0% respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.11
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• pp.592-604
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• 2017

A chiller, having a thermal storage system, can contribute to load-leveling and can reduce the cost of electricity by using electricity at night. In this study, the control experiments and simulations are conducted using both conventional and advanced methods for the building cooling system. Advanced approaches, such as the "region control method", divide the control region into five zones according to the size of the building load, and determines the cooling capacities of the chiller and thermal storage. On the other hand, the "dynamic programming method" obtains the optimal cooling capacities of the chiller and thermal storage by selecting the minimum-cost path by carrying out repetitive calculations. The "thermal storage priority method" shows an inferior chiller performance owing to the low-part load operation, whereas the chiller priority method leads to a high electric cost owing to the low utilization of thermal storage and electricity at night. It has been proven that the advanced control methods have advantages over the conventional methods in terms of electricity consumption, as well as cost-effectiveness. According to the simulation results during the winter season, the electric cost when using the dynamic programming method was 6.5% and 8.9% lower than that of the chiller priority and the thermal storage priority methods, respectively. It is therefore concluded that the cost of electricity utilizing the region control method is comparable to that of the dynamic programming method.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.02a
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• pp.1-11
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• 2000

The use of Compaction Grouting evolved in 1950's to correct structural settlement of buildings. Over the almost 50 years, the technology has been developed and is currently used in wide range of applications. Compaction Grouting, the injection of a very stiff, 'zero-slump' mortar grout under relatively high pressure, displaces and compacts soils. It can effectively repair natural or man-made soil strength deficiencies in variety of soil formations. Major applications of Compaction Grouting include densifying loose soils or fill voids caused by sinkholes, poorly compacted fills, broken utilities, improper dewatering, or soft ground tunneling excavation. Other applications include preventing liquefation, re-leveling settled structures, and using compaction grout bulbs as structural elements of minipiles or underpinning. In this paper, on the basis of the case history constructed in this year, a study has been performed to analyze the basic mechanism of the Compaction Grouting. Also, the effectiveness of the ground improvement and the bearing capacity of the Compaction Pile has been verified by the Cone Penetration Test(CPT) and Load Test. Relatively uniform Compaction grouting column could be maintained by planning the Quality Control in the course of grouting. And, the Quality Control Plan has been conceived using grout pressure, volume of grout and drilling depth.

• Journal of the Korea Concrete Institute
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• v.15 no.5
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• pp.739-746
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• 2003

Various researches on the application of polymer dispersions to the cement mortar and concrete have been carried out in many countries like America, Japan and Germany and so on due to their high performance and good modification effect. PAE of polymer dispersion widely used in situ was employed that the high flowability may be induced in the cement mortar. In order to investigate the modification of cement mortar with high flowability by PAE and fracture mode of adhesive strength properties in tension of that, experimental parameters were set as PAE solid-cement ratio(P/C) and cement: fine aggregate(C:F) and the experiments such as unit weight, flow, consistency change, crack resistance and segregation that inform on the general properties have been done. Adhesion in tension is measured with a view to comprehending the properties and fracture mode in tensile load. Consistency change of cement mortar modified by PAE did grow better as the ratio of PAE solid-cement increased and was much superior to that of resin based flooring such as polyurethane and epoxy which recorded the loss of consistency in 90 min. after mixing. Adhesive strength in tension increased with continuity during curing period and showed the maximum in case of C:F=1:1 and P/C=20%.

• Membrane Journal
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• v.21 no.2
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• pp.107-117
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• 2011

The all vanadium redox-flow battery (V-RFB) is investigating as one of large-scale power storage systems. Particularly, V-RFB is being investigated as one of the power storage systems for the load leveling and output power equalization of the power systems using renewable energy such as solar and wind. In this paper, it was explained for the principle and construction, recent research review, economy, element technology in V-RFB.