• Journal of Korean Vacuum Science & Technology
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• v.3 no.2
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• pp.134-138
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• 1999

We have setup a compact and useful in-situ SMOKE system in order to study surface magnetism of ultra-thin films. Since the longitudinal or polar magnetic fields can be applied to the sample by just rotating the sample manipulator, It is very simple to take hysteresis curve for in-plane or polar surface magnetism. The SMOKE system was tested by investigating the surface magnetism of ultra-thin Co film deposited on Pt(111) surface.

• Journal of Power System Engineering
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• v.18 no.1
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• pp.51-56
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• 2014

In this paper, the performance of the $CO_2-C_2H_6-N_2$ cascade liquefaction cycle with respect to temperature differences in the LNG heat exchangers is analyzed theoretically using HYSYS software and then compared the COP(coefficient of performance) of the cascade liquefaction cycles using $C_3H_8-C_2H_4-C_1H_4$ and $CO_2-N_2O-N_2$. In comparison of COP of three cycles, the cascade liquefaction cycles using $C_3H_8-C_2H_4-C_1H_4$ showed the highest COP. And the liquefaction cycle using $CO_2-C_2H_6-N_2$ and $CO_2-N_2O-N_2$ presented the second and third highest COP, respectively. In case of COP, the $C_3H_8-C_2H_4-C_1H_4$ cascade liquefaction cycle yields better COP. But, in terms of the environment and maintain, it is confirmed that the cascade liquefaction cycle using $CO_2-C_2H_6-N_2$ provides favorable characteristics.

• Nuclear Engineering and Technology
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• v.35 no.2
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• pp.165-170
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• 2003

We developed an improved 3-PM liquid scintillation counting (3-PM LSC) method in which three detectors can be displaced to back and forth directions, and a data acquisition system being able to provide the values for all parameters required for the method. The detectors are entirely located in a 20-mm lead chamber of an inner diameter of 500 mm. A saw-toothed gear ties up all detectors so as to move them uniformly, up to 50 mm with unit of 1 mm. The data acquisition system was designed in an integrated circuit to perform the necessary works such as fast amplification, discrimination, coincidence and logic analysis. It generates values of nine parameters among twelve's generated in the 3-PH LSC method. The dead time of each counting channel is of extending type, valving from 10 to 100 $mutextrm{s}$. We measured the TDCR values with an unquenched liquid scintillation source 1"C by displacing the detectors with a step of 2.5 mm away from counting vial. Their values were derived on the range from 0.9 to 0.6. The extent is three times wider than those regions observed by applying the defocalization technique.ique.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.441-442
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• 2000

• Journal of Power System Engineering
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• v.3 no.3
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• pp.5-13
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• 1999

• Journal of the Korean Ceramic Society
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• v.30 no.4
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• pp.259-264
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• 1993

In this research, the organic tenside R11OSO3- with long alkyl-chain was synthesized, and the intercalationscomplexes fo montmorillonite were formed by the substitution of metallic cation in the montmorilonite by the synthesized organic tenside in following two methods, and the behaviors of the tenside R11OSO3- in the interlamellar space of montmorillonite were studied udner various conditions: 1) In order to protonize the sulfate group of R11OSO3-, the H3O-Montomorillonite, which acts as acid, was synthesized. And then, the organic tenside was intercalated in the interlamellar space of this H3O-Montomorillonite. And thus, the intercalations-complex of R11S-H3O-Montomorillonite was formed. The basal spacing obtained was about 33.84$\AA$. 2) The betaine compound R11OSO3- as a neutral molecule was direct intercalated in the interlamellar space of Na-Montmorillonite under water, and the intercalations-complexes of R11S-H2O-Montmorillonite was synthesized. In this case, the based spacing of bout 23.62$\AA$ was obtained.

• Journal of Soil and Groundwater Environment
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• v.7 no.1
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• pp.25-31
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• 2002

This study attempts to elucidate the possibility of treating landfill leachate by steelers' dust/${H_2}{O_2}$ system in a well-mixed batch reactor. Experiments were conducted to investigate the effects of operating variables such as pH, dust and ${H_2}{O_2}$ dosages and ${H_2}{O_2}$ injection method on the treatment efficiency, Contaminant concentrations were identified by TOC (Total Organic Carbon) analyzer. Experimental observations showed the possibility of steelers' dust as a catalytic reagent in the ${H_2}{O_2}$/dust system. The batch experiments showed that the optimal $H_2O$$_2$ and dust dosage, 20g/L dust. 2,000mg/L ${H_2}{O_2}$ removed about 75% of initial TOC concentration (250mg/1) within 60 min. And the TOC removal in the ${H_2}{O_2}$/dust system effectively proceeded only within a limited pH range of 3-4. The stealers' dust-catalyzed oxidative treatment of landfill leachate was more efficient compared with the $FeSO_2$catalyzed system (Fenton oxidation) for the removal rate and the cost.

• Bulletin of the Korean Chemical Society
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• v.21 no.11
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• pp.1095-1100
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• 2000

we have proposed a three-dimensional GLE approach to gas-surface reactive scattering, model H + H $${\rightarrow}$H_2/Si(100)-(2$ ${\times}$1) system, and the implementation of 3D GLE method on the hydrogen on silicon surface has been presented. The formalism and algori thm of the 3D GLE are worked properly in the reactive scattering system. The calculated normal mode frequencies of surface vibrations were almost identical to previous harmonic slab calculations. The reaction probabilities were calculated for two energies. The calculations show that a very large amount of energy is transferred in surface in low energy scattering. Three different types of reaction mechanisms has been observed, which can not be shown in flat and rigid surface models. Further work on the reaction mechanisms and calculations of the vibrational and rotation distributions of products is in progress. The results will be reported elsewhere soon.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.499-508
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• 2008

Frequency regulation in off-normal conditions has been an important problem in electric power system design/operation and is becoming much more significant today due to the increasing size, changing structure and complexity of interconnected power systems. Increasing economic pressures for power system efficiency and reliability have led to a requirement for maintaining power system frequency closer to nominal value. This paper presents a decentralized frequency control framework using a modified low-order frequency response model containing a proportional-integral(PI) controller. The proposed framework is suitable for near-normal and emergency operating conditions. An $H_{\infty}$ control technique is applied to achieve optimal PI parameters, and an analytic approach is used to analyse the system frequency response for wide area operating conditions. Time-domain simulations with a multi-area power system example show that the simulated results agree with those predicted analytically.

• International Journal of Computer Science & Network Security
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• v.23 no.3
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• pp.130-138
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• 2023

The Smart grids are considered as multi-disciplinary power systems where the communication networks are highly employed. This paper presents optimal wide area measurement system (WAMS) configuration in Nordic power system. The transition from SCADA to WAMS becomes now trend in all power systems to ensure higher reliability and data visibility. The optimization applied in this research considered the geographical regions of the Nordic power system. The research considered all the devices of WAMS namely phasor measurement units (PMUs), phasor data concentrators (PDCs) and communication links. The study also presents two scenarios for optimal WAMS namely base case and N-1 contingency as different operating conditions. The result of this research presents technical and financial results for WAMS configuration in a real power system. The optimization results are performed using MATLAB 2017a software application.