• Journal of Astronomy and Space Sciences
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• 제39권2호
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• pp.35-42
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• 2022

During their respective missions, the spacecraft Voyager and Cassini measured several Saturn magnetosphere parameters at different radial distances. As a result of information gathered throughout the journey, Voyager 1 discovered hot and cold electron distribution components, number density, and energy in the 6-18 Rs range. Observations made by Voyager of intensity fluctuations in the 20-30 keV range show electrons are situated in the resonance spectrum's high energy tail. Plasma waves in the magnetosphere can be used to locate Saturn's inner magnetosphere's plasma clusters, which are controlled by Saturn's spin. Electromagnetic electron cyclotron (EMEC) wave ring distribution function has been investigated. Kinetic and linear approaches have been used to study electromagnetic cyclotron (EMEC) wave propagation. EMEC waves' stability can be assessed by analyzing the dispersion relation's effect on the ring distribution function. The primary goal of this study is to determine the impact of the magnetosphere parameters which is observed by Cassini. The magnetosphere of Saturn has also been observed. When the plasma parameters are increased as the distribution index, the growth/damping rate increases until the magnetic field model affects the magnetic field at equator, as can be seen in the graphs. We discuss the outputs of our model in the context of measurements made in situ by the Cassini spacecraft.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.589-596
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• 2020

Many components in the assembly section of Sodium-cooled Fast Reactor are made of good corrosionresistant 316 LN Stainless Steel material. To avoid self-welding of the components with the coolant sodium at elevated temperature, hardfacing is inevitable. Ni-based colmonoy-5 is used for hardfacing due to its lower dose rate by Plasma Transferred Arc process due to its low dilution. Since Ni-Cr-B-Si alloy becomes very fluidic while depositing, the major height of the weld overlay rests inside the groove. Hardfacing is also done over the plain surface where grooving is not possible. Therefore, grooved and ungrooved hardfaced specimens were prepared at different travel speeds. Fe content at every 100 ㎛ of the weld overlay was studied by Energy Dispersive Spectroscopy and also the micro hardness was determined at those locations. A correlation between iron dilution from the base metal and the micro hardness was established. Therefore, if the Fe content of the weld overlay is known, the hardness at that location can be obtained using the correlation and vice-versa. A new correlation between micro hardness and dilution coefficient is obtained at different locations. A comparative study between those specimens is carried out to recommend the optimum travel speed for lower dilution.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.268-269
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• 2008

Charging of spacecraft occurs in plasma and radiation environment. Especially, we focused on an accident caused by internal charging in a glass material that was used as the cover plate of solar panel array, and tried to measure the charge distribution in glass materials under electron beam irradiation by using a PEA (Pulsed Electro-Acoustic method) system. In the case of a quartz glass (pure $SiO_2$), no charge accumulation was observed either during or after the electron beam irradiation. On the contrary, positive charge accumulation was observed in glass samples containing metal-oxide components. It is found that the polarity of the observed charges depends on the contents of the impurities. To identify which impurity dominates the polarity of the accumulated charge, we measured charge distributions in several glass materials containing various metal-oxide components and calculated the trap energy depths from the charge decay characteristics of all glass samples.

• Journal of Power Electronics
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• 제6권1호
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• pp.73-82
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• 2006

Plasma display panels (PDPs) have a serious thermal problem, because the luminance efficiency of a conventional PDP is about 1.5 1m/W and it is less than $3\~5\;lm/W$ of a cathode ray tube (CRT). Thus there is a need for improving the luminance efficiency of the PDP. There are several approaches to improve the luminance efficiency of the PDP and we adopted a driving PDP at high frequency range from 400kHz up to over 700kHz. Since a PDP is regarded as an equivalent inherent capacitance, many types of sustaining drivers have been proposed and widely used to recover the energy stored in the PDP. However, these circuits have some drawbacks for driving PDPs at high frequency ranges. In this paper, we investigate the effect of the parasitic components on the PDP itself and on the driver when the reactive energy of the panel is recovered. Various drivers are classified and evaluated based on their suitability for high frequency drivers. Finally, a current-fed driver with a DC input voltage bias is proposed. This driver overcomes the effect of parasitic components in the panel and driver. It fully achieves a ZVS of all full-bridge switches and reduces the transition time of the panel polarity. It is tested to validate the high frequency sustaining driver and the experimental results are presented.

• 한국위성정보통신학회논문지
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• 제6권2호
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• pp.102-106
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• 2011

태양폭발, 코로나물질방출(Corona Mass Ejection, CME)등의 태양활동을 포함한 우주환경(space environment)은 결코 인간에게 우호적이지만은 않다. 특히 인공위성에게는 치명적일 수 있다. 그 중에서 정지궤도에 있는 통신위성에게는 상기와 같은 급격한 태양활동뿐만 아니라 지속적으로 끊임없이 배출되는 전자, 양성자등 플라즈마 입자들로 인해 수명이 단축되고 있다. 통신위성을 구성하는 능동부품들은 플라즈마 입자들에 특히 약하기 때문이다. 이를 방지하기 위하여 방사능 차폐(Radiation Shielind)등을 하지만 이에 대한 비용이 매우 많이 드는 것이 사실이다. 그러므로 적절한 차폐가 필요하며 이를 위해서는 우주환경의 연구가 필요하다. 본 연구에서는 저궤도부터 우주탐사용 위성까지 모든 궤도영역의 인공위성의 이상현상등을 분석한 후 이것이 태양폭발, 지자기 폭풍등 우주환경이벤트와의 연관성을 조사해보고자 한다.

• BMB Reports
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• 제28권3호
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• pp.275-280
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• 1995

The respiratory burst oxidase of neutrophils is a multicomponent enzyme, domant in resting cells, that catalyzes the reduction of oxygen to $O_{2}^{-}$ at the expense of NADPH. In the resting neutrophil, some of the components of the oxidase, including proteins p47 and p67, are in the cytosol, while the rest are in the plasma membrane. Recent evidence has suggested that at least some of the cytosolic oxidase components exist as a complex. The cytosolic complex with a molecular weight of ~240 kDa was found to bind to blue-agarose and 2',5'-ADP-agarose, which recognize nucleotide requiring enzymes. In order to identify the nucleotide binding component of the cytosolic complex we purified recombinant p47 and p67 fusion proteins using the pGEX system. Pure recombinant p47 was retained completely on 2',5'-ADP-agarose, whereas pure recombinant p67 did not bind to these affinity beads. On the basis of these results, we infer that p47 may contain the nucleotide binding site.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.617-619
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• 2008

Inorganic-organic hybrid multilayers were formed on the plastic substrate to enhance the barrier properties of substrate to water vapor and oxygen transport. Plasma pretreatment of substrate with $Ar/O_2$ lead to adhesion improvement and the densification of inorganic layer on the substrates. Combination of $SiO_xN_y$ layer and silanenanoclay composite layer offered quite good barrier properties (WVTR and OTR) to PES substrate.

• ETRI Journal
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• 제34권5호
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• pp.779-782
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• 2012

$CuIn_{1-x}Ga_xSe_2$ (CIGS) thin films are grown on Mo/soda lime glass using a reactive sputtering process in which a Se cracker is used to deliver reactive Se molecules. The Cu and $(In_{0.7}Ga_{0.3})_2Se_3$ targets are simultaneously sputtered under the delivery of reactive Se. The effects of Se flux on film composition are investigated. The Cu/(In+Ga) composition ratio increases as the Se flux increases at a plasma power of less than 30 W for the Cu target. The (112) crystal orientation becomes dominant, and crystal grain size is larger with Se flux. The power conversion efficiency of a solar cell fabricated using an 800-nm CIGS film is 8.5%.

• ETRI Journal
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• 제31권6호
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• pp.675-679
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• 2009

$Ti_xSi_{1-x}O_y$ (TSO) thin films are fabricated using plasma-enhanced atomic layer deposition. The Ti content in the TSO films is controlled by adjusting the sub-cycle ratio of $TiO_2$ and $SiO_2$. The refractive indices of $SiO_2$ and $TiO_2$ are 1.4 and 2.4, respectively. Hence, tailoring of the refractivity indices from 1.4 to 2.4 is feasible. The controllability of the refractive index and film thickness enables application of an antireflection coating layer to TSO films for use as a thin film solar cell. The TSO coating layer on an Si wafer dramatically reduces reflectivity compared to a bare Si wafer. In the measurement of the current-voltage characteristics, a nonlinear coefficient of 13.6 is obtained in the TSO films.

• 한국대기환경학회지
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• 제11권4호
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• pp.331-337
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• 1995

This study was carried out to investigate the chemical composition of dustfall at Cheju(mean sea level; 71.7m, 33$^{\circ}$17'N, 126$^{\circ}$10'E) and Ullung island(mean sea level; 22.1m, 38$^{\circ}$29'N, 130$^{\circ}$54'E) from October 1993 to september 1994. The dustfall matter samples were collected by deposit gauges. The ionic components of each samples was analyzed by Ion Chromatograpy (Dionex 4000i), While heavy metals by Inductively Coupled Plasma Atomic Emission Spectrometry(ICP/AES; Shimadzu ICP-4). The results for seasonal variation of dustfall matter matter total amount, water-soluble ionic components and water-soluble ionic components total deposition amount to two sites were compared each other. The seasonal variations of dustfall amount at Ullung and Cheju island were found in order of Spring>Winter>Fall>Summer, and the maximum of dustfall amount were during the Yellow Sand period. Also, Total amount of water-soluble components except for $F^{[-10]}$ were high in Cheju more than Ullung island.more than Ullung island.