• Journal of the Society of Naval Architects of Korea
• /
• v.50 no.2
• /
• pp.120-128
• /
• 2013

This paper presents the results of sloshing experiments having different fluids in model tanks with various density ratios. The experimental model consisting water and air at ambient, which has been commonly used, is not consistent in density ratio with that of an actual LNG cargo tank. Therefore, an advanced experimental scheme is developed to consider the same density ratio of LNG and NG by using a mixed gas of sulfur hexafluoride ($SF_6$) and nitrogen ($N_2$). For experimental observation, a two-dimensional model tank of 1/40 scale and a three-dimensional model tank of 1/50 scale have been manufactured and tested at various conditions. Two different fillings with various excitation frequencies under regular motions have been considered for the two-dimensional model tank, and three different filling levels under irregular motions have been imposed for the three-dimensional model tank. The density ratio between gas and liquid varies from the ratio of the ambient air and water to that of the actual LNG cargo container, and the different composition of gas is used for this variation. Based on the present experimental results, it is found that the decrease of sloshing pressure is predicted when the density ratio increases.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.8
• /
• pp.98-103
• /
• 2015

Power plant is that very high reliability when industrial and economic impact on the overall electric power system is required, it is essential to improve the reliability, especially the fault prediction diagnosis. Since an accident caused by the partial discharge in the power plant is above state has a faster response characteristic than the other indications in the case of any, the partial discharge generated in the power plant immediately detect the deterioration of insulation due to the accident of the power plant and the non-drawn It should prevent or reduce. Partial Discharge Measuring Systems for UHV SF6 Gas Insulated Switchgear and power transformer on site installed has some probability of abnormal recognition in case of non-flexible deal with on site noise. Many methode to eliminate these kinds of noises, UHF Detection System is chosen as purchase description in Korea, but this system having a bandwidth between 500MHz 1.5GHz wide band. Initial install periods(about 20 years ago), this band had no strong signal source, but in these days this wide band have strong signals, such as LTE. So, module described in this paper is designed as simultaneously use with wide and narrow band for solve this noise problem, and introduce this system.

• Applied Chemistry for Engineering
• /
• v.30 no.1
• /
• pp.108-113
• /
• 2019

In this study, the decomposition characteristics of perfluorinated compounds generated in semiconductor manufacturing process were investigated by using a high temperature plasma. The analysis results revealed that $CF_4$ and $SF_6$ showed the highest efficiency at 12.8 kW power, but no significant difference was observed at the power above. Experimental results showed that the maximum efficiency was obtained at the flow rate of about 14 mL/min and the treatment efficiency decreased as the flow rate increased or decreased with respect to the flow rate of 14 mL/min. As a result, the decomposition characteristics of perflurocompounds (PFCs) using a high temperature plasma could be grasped, and also the basis for the treatment of PFCs and greenhouse gases generated in the semiconductor manufacturing process could be obtained.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.9
• /
• pp.1374-1379
• /
• 2015

Time Domain Reflectometry(TDR) using microwave bands, including broadband spectrum that occurs at the range of rates that start between partial discharge position it easier to make the techniques that could be measured. Partial discharge in the Gas Insulated Switchgear(GIS), the dielectric constant in the band more than GHz different the insulating material if you want to organize, and the insulating material regardless of how partial discharge position in the SF6 gas Partial Discharge by applying the heritability estimated its position, but the position error occurred about 23 percent of the existing way, correct in not suitable location tracking the outbreak PD. This technique the rate of other dielectric that make up the power apparatus heterology is measured at the function to slow the progression of the electromagnetic waves apart by calculating the partial discharge as the location, A simple way to track. Dielectric using other methods proposed new structure can calculate the speed of heritability PD is occurring can measure.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1797-1799
• /
• 2002

$SF_6$ 가스로 절연되는 GIS (Gas Insulated Switchgear)는 매우 우수한 신뢰성을 확보하고 있지만 사고 발생 시 파급효과가 매우 크므로 상시 감시할 수 있는 진단기술이 요구된다. 본 논문에서는 GIS 내부에서 발생하는 신호를 검출하기 위해서 전기적인 방법과 비전기적인 측정 법을 통해 전자파. 초음파, 전류펄스를 측정하고 비교하였다. GIS 내부알루미늄도체에 침 결함을 고정시켜 전원전압 인가 시 발생되는 부분방전신호를 UHF, AE, CT센서로 검출하였다. 측정 결과 UHF센서와 CT센서로 검출되어진 신호는 매우 유사하게 측정되었고 초음파와 전자파를 검출한 결과 진행속도 차이로 발생되는 시간지연현상이 발생되었다. GIS내 부분방전발생 시 발생되는 전자파 스펙트럼 분석결과도 650MHz에서부터 935MHz까지의 주파수대역이 측정되었다. 이후에는 현장에서 운전중인 GIS내부에서 발생되는 결함들을 실제와 가깝게 모델링하여 발생되는 부분방전신호를 스펙트럼 분석하여 대역에 맞는 UHF센서 개발에 노력하고자 한다. 또한 결함의 종류와 형태에 따라 다르게 발생되는 부분방전신호를 검출하여 측정하고 이를 진단하는 연구가 계속 진행되어야 할 것으로 사료된다.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.8
• /
• pp.1383-1388
• /
• 2007

Recently, the semiconductor and display industries have tried to reduce the emissions of perfluorocompounds (PFCs) from the globally environmental regulation. Total amount of PFC emission can be calculated from the flow rate and the partial pressures of PFCs. For the precise measurement of PFC emission amount, the mass flow controlled helium gas was continuously injected into the equipment of which scrubber efficiency is being measured. The partial pressures of PFCs and helium were accurately measured using a mass spectrometer in each sample extracted from inlet and outlet of the scrubber system. The flow rates are calculated from the partial pressures of helium and also, PFC destruction and removal efficiency (DRE) of the scrubber is calculated from the partial pressure of PFC and the flow rate. Under this method, the relative expanded uncertainties of the flow rate and the partial pressures of PFCs are ± 2% (k = 2) in case the concentrations of NF3 and SF6 are as low as 100 μmol/mol.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.3
• /
• pp.507-512
• /
• 2017

Recently, more electric power facilities have been miniaturized and it is noted that the facilities maintenance will be essential through operation optimization. In this paper we applied and examined the operation optimization of electric power facilities by applying Matrix system which can improve reliability to minimize outage and recover failure rapidly when blackouts happen at 25.8kV Gas Insulated Switchgear(GIS). The fundamental problem for facilities maintenance of GIS can happen due to indeterminable internal state in real time. Matrix optimization organizes action states in all containers which contain pressurized $SF_6$ Gas such as circuit breaker, disconnector switch, bus for utilizing them each area. Then, we connect it with power system to monitor and control internal state remotely in real time, and we can minimize blackout zone or outage. Considering above process, we improved stability of overall facilities.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.10
• /
• pp.27-34
• /
• 2012

If obstacle in GIS(Gas Insulted Switchgear), its affects are great are on the community and it is consequently demanded lots of difficulities to recover and repair. Accordingly, diagnosis techniques, that are able to prevent from accidents before they happen by providing more stable and highly reliable power effectively and finding sign of the accidents is very important. A novel UHF(Ultra High Frequency)-microstrip antenna is presented. The measured impedance bandwidth of the proposed antenna is from 0.5GHz to 15GHz with the stop band from 0.5GHz to 10.7GHz for VSWR<2. Form results of this study, The antenna is will play an important role for the senser for insulation diagnosis system by UHF method of real site GIS and power equipment using $SF_6$ gas.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.454-454
• /
• 2014

Silicon microwire array is one of the promising platforms as a means for developing highly efficient solar cells thanks to the enhanced light trapping efficiency. Among the various fabrication methods of microstructures, deep reactive ion etching (DRIE) process has been extensively used in fabrication of high aspect ratio microwire arrays. In this presentation, we show precisely controlled Si microwire arrays by tuning the DRIE process conditions. A periodic microdisk arrays were patterned on 4-inch Si wafer (p-type, $1{\sim}10{\Omega}cm$) using photolithography. After developing the pattern, 150-nm-thick Al was deposited and lifted-off to leave Al microdisk arrays on the starting Si wafer. Periodic Al microdisk arrays (diameter of $2{\mu}m$ and periodic distance of $2{\mu}m$) were used as an etch mask. A DRIE process (Tegal 200) is used for anisotropic deep silicon etching at room temperature. During the process, $SF_6$ and $C_4F_8$ gases were used for the etching and surface passivation, respectively. The length and shape of microwire arrays were controlled by etching time and $SF_6/C_4F_8$ ratio. By adjusting $SF_6/C_4F_8$ gas ratio, the shape of Si microwire can be controlled, resulting in the formation of tapered or vertical microwires. After DRIE process, the residual polymer and etching damage on the surface of the microwires were removed using piranha solution ($H_2SO_4:H_2O_2=4:1$) followed by thermal oxidation ($900^{\circ}C$, 40 min). The oxide layer formed through the thermal oxidation was etched by diluted hydrofluoric acid (1 wt% HF). The surface morphology of a Si microwire arrays was characterized by field-emission scanning electron microscopy (FE-SEM, Hitachi S-4800). Optical reflection measurements were performed over 300~1100 nm wavelengths using a UV-Vis/NIR spectrophotometer (Cary 5000, Agilent) in which a 60 mm integrating sphere (Labsphere) is equipped to account for total light (diffuse and specular) reflected from the samples. The total reflection by the microwire arrays sample was reduced from 20 % to 10 % of the incident light over the visible region when the length of the microwire was increased from $10{\mu}m$ to $30{\mu}m$.

• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1888-1890
• /
• 2004

현대사회에 들어서면서, 전력수요의 중가와 전력기기산업의 고집적화에 따라 사고시에 발생하는 파급효과가 대형화되는 추세에 있다. 따라서 이를 미연에 방지하기 위한 연구가 각 분야에 걸쳐 활발하게 진행되고 있다. 이에 당사에서는 초고압 계통에서 사용되는 SF6가스 절연 GIS(Gas Insulated Switchgear) 및 Oil-Transformer에서의 부분방전 측정/분석을 위하여 UHF/AE를 이용한 on-line/portable 측정 시스템을 개발하였다. 본 논문에서는 개발/상용화 되어 field에서 사용되고 있는 시스템의 전반에 대하여 설명한다. 또한 철재 선진사와 공동 진행중인 Risk Assessment에 대하여 언급하였다.