• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.387-392
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• 2000

This paper presents an experimental study on the behavior of high strength concrete columns confined by rectangular ties under combined axial load lateral load. This test was carried on the twelve reinforced concrete columns with $200\times200\times200$mm size subjected to combined axial load and lateral load. Effects of key variables such as the axial load level, the tie yield strength, the longitudinal reinforcement ratio are studied in this research program. The results of this study show that the efficiency of high strength lateral ties increase under high axial load level over 0.4f(아래첨자) A(아래 첨자). Also we found that well confined concrete column shows second peak monent after spalling of cover concrete under high axial load level.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1657-1660
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• 2013

Short-term load forecasting for Chusok and New Year's consecutive holidays is very difficult, due to the irregular characteristics compared with ordinary weekdays and insufficient holidays historical data. During consecutive holidays of New Year and Chusok, most of industries reduce their operation rates and their electrical load levels. The correlation between businesses' operation rates and their loads during consecutive holidays of New Year and Chusok is analysed and short-term load forecasting algorithm for consecutive holidays considering businesses' operation rates of industries is proposed. Test results show that the proposed method improves the accuracy of short-term load forecasting over fuzzy linear regression method.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.6
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• pp.506-513
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• 2016

In general, LLC converters show great promise in applications that require high efficiency, especially under light load conditions. In particular, LLC converters feature wide gain capability with pulse-frequency modulation and zero voltage switching over entire load conditions. However, output voltage increases in light load conditions. In this study, Bode plot and impedance asymptotes analyses were conducted to obtain insights into the regulation characteristics of LLC converters under light load conditions. To improve the regulation characteristic of LLC converters, a new resonant tank with an additional capacitor is proposed. The design guideline for the proposed LLC converter is determined by the Bode plot and impedance asymptotes analyses. Therefore, the proposed LLC converter achieves the light load regulation while maintaining the advantages of typical LLC converters.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.1
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• pp.1-10
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• 2005

Screw compressor chillers are widely used in refrigeration for capacity over 30 RT. In general, chillers operate under part-load conditions during most of the time. Therefore, information on the characteristics of part-load is very important for better chiller performance and energy economy. In this study, performance tests of screw chiller with economizer using R22 and R407C under part-load conditions have been performed for various secondary fluid temperatures. Adoption of an economizer system increased the cooling capacity and improved COP except for lower part-load condition when economizer volume ratio is 1.01. For the same cooling capacity condition at part-load, COP's of both non-economizer and economizer system showed similar values.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.11
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• pp.902-909
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• 2003

Screw compressor type chillers are widely used in refrigeration for capacity over 30 RT. In general, chillers operate under part-load conditions. Therefore, information on characteristics at part-load is very important in view of chiller performance and energy economy. In this study, performance tests of part-load and economizer system using R22 and R407C have been performed for various secondary fluid temperatures. Adoption of an economizer system increased the cooling capacity and improved COP except for lower part-load condition when injection volume ratio is 1.01. For the same cooling capacity condition at part-load, COP of both non-economizer and economizer system showed similar values.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.7
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• pp.2354-2370
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• 2015

The advantages of employing SCTP-based Concurrent Multipath Transfer (CMT) have been demonstrated to be very useful for data delivery over multi-homed wireless networks. However, there is still significant ongoing work addressing some remaining limitations and challenges. The most important concern when applying CMT to data delivery is related to handling packet reordering and buffer blocking. Another concern on this topic is that current sender-based CMT solutions seldom consider balancing the overhead and sharing the load between the sender and receiver. This paper proposes a novel Receiver-driven Cooperation-based Concurrent Multipath Transfer solution (CMT-Rev) with the following aims: (i) to balance overhead and share load between the sender and receiver, by moving some functions including congestion and flow control from the sender onto receiver; (ii) to mitigate the data reordering and buffer blocking problems, by using an adaptive receiver-cooperative path aggregation model, (iii) to adaptively transmit packets over multiple paths according to their receiver-inspired sending rate values, by employing a new receiver-aware data distribution scheduler. Simulation results show that CMT-Rev outperforms the existing CMT solutions in terms of data delivery performance.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.905-913
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• 2017

Advanced reactor designs often feature longer operating cycles between refueling and new concepts of operation beyond traditional baseload electricity production. Owing to this increased complexity, traditional proportional-integral control may not be sufficient across all potential operating regimes. The prototypical advanced reactor (PAR) design features two independent reactor modules, each connected to a single dedicated steam generator that feeds a common balance of plant for electricity generation and process heat applications. In the current research, the PAR is expected to operate in a load-following manner to produce electricity to meet grid demand over a 24-hour period. Over the operational lifetime of the PAR system, primary and intermediate sodium pumps are expected to degrade in performance. The independent operation of the two reactor modules in the PAR may allow the system to continue operating under degraded pump performance by shifting the power production between reactor modules in order to meet overall load demands. This paper proposes a Takagi-Sugeno (T-S) fuzzy logic-based power distribution system. Two T-S fuzzy power distribution controllers have been designed and tested. Simulation shows that the devised T-S fuzzy controllers provide improved performance over traditional controls during daily load-following operation under different levels of pump degradation.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.648-653
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• 2010

Discharged pollution load for the management of Total Maximum Daily Loads (TMDLs) is calculated on the basis of rainfall data for reference year. Rainfall has an influence on discharged pollution load in unit watershed with combined sewer system. This study reviewed the status of discharged pollution load and rainfall conditions. We also investigated rainfall effects on discharged pollution load by analyzing change of the load in accordance with increase of rainfall. The change ratio of discharged pollution load was 18.6% while inflow load only 5.8% for 5 years from 2004 to 2008 in Daejeon district. The greatest rainfall and rain days were over 2 times than the least during the period. This change in rainfall could have great effect on discharged pollution load. The analysis showed that discharged pollution load increased 2.1 times in case rainfall increased 2 times and 1.2 times in case rain days increased 2 times. Rainfall effects, therefore, should be considered to make resonable evaluation of discharged pollution load in the assessment of annual performances.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.12-18
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• 2015

Recently, the development trend of turbomachinery is high capacity and high efficiency. Most of turbomachinery in the market are adopting ball bearings or air foil bearings. However, ball bearings have a limit for high speed product over $2.0{\times}10^6DN$(product of the inner diameter of the bearing in mm (D) and the maximum speed in rpm (N)). Air foil bearings have a limit for high axial load for high power products over 200~300 HP(horse power). Magnetic bearing is one of the solutions to overcome the limits of high speed and high axial load. Because magnetic bearings have no friction between the rotor and the bearings, they can reduce the load of the motor and make it possible to increase the rotating speed up to $5.0{\times}10^6DN$. Moreover, they can have high axial load capacity, because the axial load capacity of magnetic bearing depends on the capacity of the designed electromagnet. In this study, the radial and thrust magnetic bearings are designed to be applied to the 200 HP class turbo blower, and their performance was evaluated by the experiment. Based on the tests up to 26,400 rpm and 21,000 rpm under the no-load and load condition, respectively, it was verified that the magnetic bearings are stably support the rotor of the turbo blower.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1390-1395
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• 2004

Recently, the load increasement and new regenerative systems of electrified railway system make it a difficult to distinguish between the load current and fault current. The failure of traction system perhaps causes over-current to flow. The high current can collapse other railway systems. If failures of the traction system takes place, the failures are detected and protected lest it should provoke high current flow. The over current from such a traction system failure permit to charge high tension voltage and produces high temperature arc, voltage instability, current cutting, and break down railway systems. The traction system failures detect and the system has to immediately cut off from over-current flow. To isolate the failure, the system can distinguish failure current from current flows. It forces us to adapt such as a new intelligent protection system. The protective system in traction system play a role of detecting and isolating failure points. In this paper, we proposed intelligent algorithm for discriminating normal and abnormal situation instead of the system being operated abnormally.