• Membrane and Water Treatment
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• 제11권4호
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• pp.275-282
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• 2020

Hranfa's marl, a local natural mineral, is selected for the decontamination by adsorption of aqueous effluents in textile industry. Its physicochemical characterization is first performed. It is composed mainly of Calcite, Quartz, Ankerite and Muscovite. Its specific surface area is 40 ㎡ g^-1. Its adsorption performance is then tested in batch conditions using an industrial organic dye, Bemacid Red E-TL, as a model pollutant. The measured adsorption capacity of Hranfa's marl is 16 mg g^-1 which is comparable to that of other types of natural adsorbents. A hybrid process is tested coupling adsorption of the dye on marl in suspension and microfiltration. An adsorption reactor is inserted into the circulation loop of a microfiltration pilot using ceramic membranes. This makes possible a continuous extraction of the treated water provided that a periodic replacement of the saturated adsorbent is done. The breakthrough curve obtained by analyzing the dye concentration in the permeate is close to the ideal one considering that no dye will cross the membrane as long as the adsorbent load is not saturated. These first experimental data provide proof of concept for such a hybrid process.

• Nuclear Engineering and Technology
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• 제23권3호
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• pp.328-339
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• 1991

30 MW 열출력을 갖는 다목적 연구용 원자로(KMRR)가 원자력연구소에선 개발되고 있다. 열수력 연구의 일환으로 길이 방향으로 핀이 달린 연료봉다발의 압력강하특성을 실험으로 연구하였다. 본 논문에서는 넓은 유량범위에서 적용할 수 있는 핀 연료봉다발에서의 압력강하 상관식의 도출과 압력강하에 미치는 핀 영향의 조사에 중점을 두었다. 도출된 KMRR 핵연료봉다발의 마찰계수 상관식을 원형관의 실험결과와 비교하였을 때 저유량 실험영역에서는 충류시의 해석값인 64/Re 보다 큰 값을 가졌으나 Re가 증가되면 Blasius 상관식보다 낮아지는 경향을 나타내었다.

• The Journal of the Acoustical Society of Korea
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• 제18권1E호
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• pp.7-12
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• 1999

In relation to a non-destructive evaluation of irradiation damages, the changes in the hysteresis loop and Barkhausen noise amplitude and the harmonics frequency due to a neutron irradiation were measured and evaluated. The Mn-Mo-Ni low alloy steel of RPV was irradiated to a neutron fluence of 2.3 ×10/sup 19/ n/㎠ (E ≥1 MeV) at 288℃. The saturation magnetization of neutron irradiated metal did not change. The neutron irradiation caused the coercivity to increase, whereas susceptibility to decrease. The amplitude of Barkhausen noise parameters associated with the domain wall motion were decreased by a neutron irradiation. The spectrum of Barkhausen noise is analysed with an applied frequency of 4 Hz and 8 Hz, sampling time of 50 μ sec and 20 μ sec. The harmonic frequency shows 4 Hz, 8 Hz, 12 Hz and 16 Hz reflected from an unirradiated specimen. On the contrary, the harmonic frequency disappeared on the irradiated specimen. In addition to the amplitude, the harmonic frequency of Barkhausen noise is taken into accounts as a promising tool for monitoring the irradiation induced degradation of the reactor materials such as a SA508 of PWR-RPV steel and a Zr₄ of HANARO-CNH.

• 한국응용과학기술학회지
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• 제29권4호
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• pp.570-576
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• 2012

본 연구에서는 무격막식 전기분해 처리된 해수를 산화제로하는 NO 산화반응의 특성에 대해 실험적으로 살펴보았다. 폐순환 정전류 전기분해 시스템을 통해전해 시간이 길어질수록 전해수의 유효 염소농도와 온도, 염소산 이온의 비율이 증가함을 확인하였다. 전해수가 채워진 버블링 반응기에서 전해수의 유효염소농도와 온도에 비례하여 $NO_2$로 산화되는 NO의 양이 증가하였다. 또한 산화되어 생성된 $NO_2$는 전해수에 용해되어 $HNO_3{^-}$ 이온으로 존재함을 확인하였다.

• Journal of Power Electronics
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• 제3권3호
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• pp.185-196
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• 2003

In this paper, the single-phase static VAR compensator (SVC) is applied to regulate and stabilize the generated terminal voltage of the single-phase self-excited induction generator (single-phase SEIG) driven by a variable-speed prime mover (VSPM) under the conditions of the independent inductive load variations and the prime mover speed changes The conventional fixed gain PI controller-based feedback control scheme is employed to adjust the equivalent capacitance of the single-phase SVC composed of the fixed excitation capacitor FC in parallel with the thyristor switched capacitor TSC and the thyristor controlled reactor TCR The feedback closed-loop terminal voltage responses in the single-phase SEIG coupled by a VSPM with different inductive passive load disturbances using the single-phase SVC with the PI controller are considered and discussed herem. A VSPM coupled the single-phase SEIG prototype setup is established. Its experimental results are illustrated as compared with its simulation ones and give good agreements with the digital simulation results for the single-phase SEIG driven by a VSPM, which is based on the SVC voltage regulation feedback control scheme.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.2053-2058
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• 2004

The pressurized light water cooled, medium power (330 MWt) SMART (System-integrated Modular Advanced ReacTor) has been under development at KAERI for a dual purpose : seawater desalination and electricity generation. The SMART design verification phase was followed to conduct various separate effects tests and comprehensive integral effect tests. The high temperature / high pressure thermal-hydraulic test facility, VISTA(Experimental Verification by Integral Simulation of Transient and Accidents) has been constructed to simulate the SMART-P (the one fifth scaled pilot plant) by KAERI. Experimental tests have been performed to investigate the thermal-hydraulic dynamic characteristics of the primary and the secondary systems. Heat transfer characteristics and natural circulation performance of the PRHRS (Passive Residual Heat Removal System) of SMART-P were also investigated using the VISTA facility. The coolant flows steadily in the natural circulation loop which is composed of the steam generator (SG) primary side, the secondary system, and the PRHRS. The heat transfers through the PRHRS heat exchanger and ECT are sufficient enough to enable the natural circulation of the coolant.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2000년도 학술발표대회 논문집 제19권 2호
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• pp.231-234
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• 2000

In relation to a non-destructive evaluation of irradiation damage of micro-structure of interstitial, void and dislocation, the changes in the hysteresis loop and Barkhausen noise amplitude and the harmonics frequency due to neutron irradiation were measured and evaluated. The Mn-Mo-Ni low alloy steel of reactor pressure vessel was irradiated to a neutron fluence of $2.3\times10^{19}n/cm^2$ $(E\ge1MeV)$ at $288^{\circ}C.$The saturation magnetization of neutron irradiated metal did not change. Neutron irradiation caused the coercivity to increase, whereas susceptibility to decrease. The amplitude of Barkhausen noise parameters associated with the domain wall motion were decreased by neutron irradiation. The spectrum of Barkhausen noise was analyzed with an applied frequency of 4Hz and 8Hz, and a sampling time of 50 $\mu$ sec and 20 $\mu$ sec. The harmonic frequency of Joule effect shows 4Hz, 8Hz, 12Hz and 16Hz reflected from an unirradiated specimen. On the contrary, the harmonic frequency disappeared for the irradiated specimen. Harmonic frequency of induced voltage of sinusoidal magnetic field And Spectrum of Barkhausen noise on material is determined.

• Nuclear Engineering and Technology
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• 제47권6호
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• pp.647-661
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• 2015

The supercritical $CO_2$ (S-$CO_2$) Brayton cycle has recently been gaining a lot of attention for application to next generation nuclear reactors. The advantages of the S-$CO_2$ cycle are high efficiency in the mild turbine inlet temperature region and a small physical footprint with a simple layout, compact turbomachinery, and heat exchangers. Several heat sources including nuclear, fossil fuel, waste heat, and renewable heat sources such as solar thermal or fuel cells are potential application areas of the S-$CO_2$ cycle. In this paper, the current development progress of the S-$CO_2$ cycle is introduced. Moreover, a quick comparison of various S-$CO_2$ layouts is presented in terms of cycle performance.

• 한국재료학회지
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• 제25권8호
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• pp.376-385
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• 2015

The effects of Nb and Cr addition on the microstructure, corrosion and oxide characteristics of Zr based alloys were investigated. The corrosion tests were performed in a pressurized water reactor simulated-loop system at $360^{\circ}C$. The microstructures were examined using OM and TEM, and the oxide properties were characterized by low-angle X-ray diffraction and TEM. The corrosion test results up to 360 days revealed that the corrosion rates were considerably affected by Cr content but not Nb content. The corrosion resistance of the Zr-xNb-0.1Sn-yCr quaternary alloys was improved by an increasing Nb/Cr ratio. The crystal structure of the precipitates was affected by a variation of the Nb/Cr ratio. The Zr-Nb beta-enriched precipitates were mainly formed in the high Nb/Cr ratio alloy while $Zr(NbCr)_2$ precipitates were frequently observed in the low Nb/Cr ratio alloy. The studies of oxide characteristics revealed that the corrosion resistance was related to the crystal structure of the precipitate.

• 전력전자학회논문지
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• 제10권4호
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• pp.373-379
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• 2005

본 논문에서는 인버터를 구동하는 용도의 직류전원장치에 대한 제어 알고리즘 개발을 목표로 하고 있으며, 구동과 회생기능을 갖는 전압형 PWM 컨버터에서 운전시 전원의 불평형을 보상하는 제어방법을 제안한다. 교류전원에 대하여 컨버터가 항상 평형상태를 유지하는 방법은 전류제어 루프에 의하여 불평형 상태를 보상하는 방법을 사용하였으며, 불평형의 제어는 전력변환기의 구성면에 있어서 각상의 리액턴스가 같지 않은 누설변압기 등의 사용을 가능하게 하므로 제안된 전력변환기의 하드웨어와 제어 알고리즘은 장치의 소형화와 효율향상에 기여할 것이다.