• Title/Summary/Keyword: Reactor stability

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Coordinated Voltage-Reactive Power Control Schemes Based on PMU Measurement at Automated Substations

  • Choi, Yun-Hyuk;Kang, Sang-Gyun;Lee, Byongjun
    • Journal of Electrical Engineering and Technology
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    • v.10 no.4
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    • pp.1400-1407
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    • 2015
  • This paper deals with methodology to control an automatic substation system. The control system can predict the power system condition by a voltage stability index (VSI). The strategies in this paper is called as Voltage-Reactive Power Control (VRPC), which regulates an abnormal voltage of a target substation by using coordination between tap changers and shunt capacitor/reactor. This method is efficient for better voltage profile. The monitoring substation includes whole of substations around the contingency event. The control quantities of the monitoring substations are decided by the calculation of the VSI, called as a Z-index. Case studies with BC Hydro-Quebec system are presented to illustrate this approach using real-time simulator.

Seismic Analysis of Horizontal-Type Multi-Stage Centrifugal Pump using Finite Element Method (유한요소법을 이용한 수평형 다단원심펌프의 내진해석)

  • 조진래;이홍우;김민정;하세윤
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.6
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    • pp.790-796
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    • 2003
  • As a fluid machinery for piping liquid in the reactor cooling system, multi-stage centrifugal pump requires the structural dynamic stability against external dynamic excitation. This paper is concerned with the finite element analysis of its eigen behavior and seismic response to RRS(Required Response Spectrum) curves in the case of SSE (Safe Shutdown Earthquake). Through the finite element analysis, the major vibration characteristics of multi-stage centrifugal pump(MSCP) are investigated and seismic qualification based on the IEEE codes is executed. The numerical results show that the MSCP used in this study has enough seismic strength.

A Study on the Oxidation of CO and $C_3H_6$ over Noble Metal Supported Catalysts on Monolith (Monolith에 담지한 귀금속촉매상에서 CO와 $C_3H_6$의 동시적 산화반응에 관한 연구)

  • 김태원;고형림;김재형;김경림
    • Journal of Korean Society for Atmospheric Environment
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    • v.14 no.1
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    • pp.63-72
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    • 1998
  • Simultaneous CO and $C_3H_6$ oxidation was carried out over noble metal supported monolith catalysts in a flow thorugh type reactor at the temperature ranging from room temperature to $500^\circ$C. Pt and Pd were selected as major active species, 10wt% of Ce was impregnated as an additive and alumina and silica were used as supports. The reactant gases were simulated and the reaction products were analyzed by on-line G.C.. EDX, SEM, TGA, XRD and optical microscope were used to analyze the characteristics of the prepared catalysts. Under the given conditions in this study, the catalysts supported on alumina showed better activity for CO oxidation, while Pd catalysts showed better activity for $C_3H_6$ oxidation. The improvement of conversion due to increase in thermal stability possibily by Ce addition was observed only for Pt catalysts.

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Treatment of Wastewater from Purified Terephtalic Acid (PTA) Production in a Two-stage Anaerobic Expanded Granular Sludge Bed System

  • Lee, Young-Shin;Han, Gee-Bong
    • Environmental Engineering Research
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    • v.19 no.4
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    • pp.355-361
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    • 2014
  • The wastewater treatment with a two-phase expanded granular sludge bed (EGSB) system for anaerobic degradation of acetate, benzoate, terephtalate and p-toluate from purified terephtalic acid (PTA) production was studied. The feasibility and effectiveness of the system was evaluated in terms of organic oxidation by chemical oxygen demand (COD), gas production, bacterial adaptability and stability in the granular sludge. Average removal efficiencies 93.5% and 72.7% were achieved in the EGSB reactors under volumetric loading rates of $1.0-15kg-COD/m^3/day$ and terephtalate and p-toluate of 351-526 mg/L, respectively. Gas production reached total methane production rate of 0.30 L/g-COD under these conditions in the sequential EGSB reactor system. Higher strength influent COD concentration above 4.8 g-COD/L related to field conditions was fed to observe the disturbance of the EGSB reactors.

EVALUATION OF HYDROGEN INDUCED DISBONDING FOR CR-MO-V STEEL/AUSTENITIC STAINLESS OVERLAY

  • Kim, Byung-Hoon;Kim, Dong-Jin;Kim, Jeong-Tae
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.211-216
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    • 2002
  • To investigate transition region in welded overlay relating to disbonding crack, the effect of vanadium addition on disbonding of Cr-Mo steels overlay welded with austenitic stainless steel was studied. V modified Cr-Mo steels have a higher resistance to disbonding than V free Cr-Mo steel. One reason is due to the fact that fine vanadium carbide precipated in base metal traps hydrogen and thus decreases the susceptibility to the disbonding. The second is related to the higher stability of the vanadium and stable carbides formed during PWHT, in which the carbon diffusion to the interface is lower than for V free Cr-Mo steel. Decreasing the carbon content at the interface of the weld overlay shows good resistance to the disbonding. Hence, it is important to control the carbon content at the interface of the weld overlay.

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The reduction of spatter in $CO_2$ inverter Arc Weling machine by the current control at the moment of short (단락순간의 전류제어에 의한 $CO_2$ 인버터 아크 용접기의 스패터 저감)

  • 고재석;채영민;이승요;목형수;최규하
    • Proceedings of the KIPE Conference
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    • 1999.07a
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    • pp.585-590
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    • 1999
  • The conventional $CO_2$ inverter arc machine has constant voltage output characteristic and uses constant wire speed controller for welding current control. By adoption of PWM inverter to the welding machine, the spattering was reduced rather than the thyrister arc welding machine or AC arc welding machine. Moreover, by the high switching frequency, the output reactor size could be reduced evidently. Recently, the studies on optimal voltage and current waveform for the welding performance improvement have been studied. In this paper, a new instantaneous output current control scheme during the short circuit mode was proposed and showed the capability of arc stability improvement and the reduction of spatter generation.

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Bulk graphite: materials and manufacturing process

  • Lee, Sang-Min;Kang, Dong-Su;Roh, Jea-Seung
    • Carbon letters
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    • v.16 no.3
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    • pp.135-146
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    • 2015
  • Graphite can be classified into natural graphite from mines and artificial graphite. Due to its outstanding properties such as light weight, thermal resistance, electrical conductivity, thermal conductivity, chemical stability, and high-temperature strength, artificial graphite is used across various industries in powder form and bulk form. Artificial graphite of powder form is usually used as anode materials for secondary cells, while artificial graphite of bulk form is used in steelmaking electrode bars, nuclear reactor moderators, silicon ingots for semiconductors, and manufacturing equipment. This study defines artificial graphite as bulk graphite, and provides an overview of bulk graphite manufacturing, including isotropic and anisotropic materials, molding methods, and heat treatment.

A Study on Discharge Phenomenon of Spherically Convergent Beam Fusion Device for Neutron Generation (중성자 발생용 구형 집속빔 핵융합 장치의 방전현상 연구)

  • Park, Jeong-Ho;Ju, Heung-Jin;Ko, Kwang-Cheol
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.5
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    • pp.467-470
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    • 2007
  • Application field of neutron beam is very broad including industry, medicine and science. But the research and development and use of neutron beam is restricted within in narrow limits in this country, because neutron beam facility is insufficient - a big research facility of nuclear reactor(HANARO) and some small industrial facilities which use radioisotope neutron source are available. This paper compare and investigate the results of experiment and numerical analysis of the discharge in the spherically convergent beam fusion device which were expected as a portable neutron source. The spherically convergent beam fusion device will offer stability in neutron production, possibility of movement for convenience, low construction cost and higher neutron flux than radioisotope neutron source. The star mode discharge which efficiently generate neutron, were observed at both results.

A Study on The Steam Generator Level Control for Nuclear Power Plant (원자력발전소 증기발생기 수위 제어에 관한 연구)

  • Moon, Byung-Heuee;Choi, Hong-Kyoo
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.172-174
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    • 1995
  • About a half of Electric power is generated by nuclear power plants in korea. So, the stable operation of nuclear power plant is very important for suppling the essential national electric power. A S/G(Steam Generator) level control is the most difficult system in PWR(Pressurized Water Reactor) nuclear power plant. Because of the non-linear and the non-nominal response of S/G level control, it Is very difficult to control the level by automatic mode or manual mode. The goal of this study is to establish and verify a advanced control algorithm by analyzing, modelling, stability calculation, controller parameter calculation, simulation for S/G level control system.

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A study on the whole cell immobilized glucose oxidase from Aspergillus niger

  • Choe, I.S.;Roh, J.K.;Han, M.H.
    • Proceedings of the Korean Society for Applied Microbiology Conference
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    • 1979.10a
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    • pp.245.2-246
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    • 1979
  • Heat treated whole cell of Aspergillus niger containing glucose oxidase-catalase system was entrapped in gelatin matrix crosslinked by glutaral-dehyde. The reaction characteristics of immobilized enzyme was studied in a fludized reactor. Heat treatment enhanced the stability and improved the properties of micellium for the immobilized process. The immobilized enzyme system showed the maximum activity at $35^{\circ}C$ and at pH 5.5. The optimum substrate concentration was 0.04M glucose. The activity of immobilized glucose oxidase was in proportion to the concentration of dissolved oxygen in reaction mixture as other reaction conditions were fixed. It was also demonstrated that the limiting factor for the activity of the immobilized glucose oxidase was the oxygen diffusion resistance which increases proportionally to the glucose concentration.

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