• Journal of the Optical Society of Korea
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• 제9권1호
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• pp.16-21
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• 2005

Using a cantilever type nanoprobe having a 100㎚m aperture at the apex of the pyramidal tip of a near-field scanning optical microscope (NSOM), nanopatterning of polymer films are conducted. Two different types of polymer, namely a positive photoresist (DPR-i5500) and an azopolymer (Poly disperse orange-3), spincoated on a silicon wafer are used as the substrate. A He-Cd laser with a wavelength of 442㎚ is employed as the illumination source. The optical near-field produced at the tip of the nanoprobe induces a photochemical reaction on the irradiated region, leading to the fabrication of nanostructures below the diffraction limit of the laser light. By controlling the process parameters properly, nanopatterns as small as 100㎚ are produced on both the photoresist and azopolymer samples. The shape and size variations of the nanopatterns are examined with respect to the key process parameters such as laser beam power, irradiation time or scanning speed of the probe, operation modes of the NSOM (DC and AC modes), etc. The characteristic features during the fabrication of ordered structures such as dot or line arrays using NSOM lithography are investigated. Not only the direct writing of nano array structures on the polymer films but also the fabrication of NSOM-written patterns on the silicon substrate were investigated by introducing a passivation layer over the silicon surface. Possible application of thereby developed NSOM lithography technology to the fabrication of data storage is discussed.

• Preventive Nutrition and Food Science
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• 제8권4호
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• pp.390-394
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• 2003

In the post-genome period, the technique for identifying gene expression has been progressed to high throughput screening. In the field of molecular nutrition, the use of screening techniques to clarify molecular function of specific nutrients would be very advantageous. In this study, we have evaluated Zn-regulated gene expression in Zn-deficient, homocystein-treated EA.hy926 cells, using cDNA microarray, which can be used to screen the expression of many genes simultaneously. The information obtained can be used for preliminary assessment of molecular and signaling events modulated by Zn under pro-atherogenic conditions. EA.hy926 cells derived from human umbilical vein endothelial cells were cultured in Zn-adequate (control, 15 $\mu$M Zn) or Zn-deficient (experimental, 0 $\mu$M Zn) Dulbecco's MEM media under high homocysteine level (100 $\mu$M) for 3 days of post-confluency. Cells were harvested and RNA was extracted. Total RNA was reverse-transcribed and the synthesized cDNA was labeled with Cy3 or Cy5. Fluorescent labeled cDNA probe was applied to microarray slides for hybridization, and the slide was then scanned using a fluorescence scanner. The expression of seven genes was found to be significantly decreased, and one significantly increased, in response to treatment of EA.hy926 cells with Zn-deficient medium, compared with Zn-supplemented medium. The upregulated genes were oncogenes and tumor suppressor genes, cell cycle-related genes and transporter genes. The down-regulated gene was RelB, a component of the NF-kappaB complex of transcription factors. The results of this study imply the effectiveness of cDNA microarray for expression profiling of a singly nutrient deficiency, namely Zn. Furthur study, using tailored-cDNA array and vascular endothelial cell lines, would be beneficial to clarify the molecular function of Zn in atherosclerosis, more in detail.

• 천문학회지
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• 제47권2호
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• pp.49-67
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• 2014

A novel method to characterize the topology of the early-universe intergalactic medium during the epoch of cosmic reionization is presented. The 21-cm radiation background from high redshift is analyzed through calculation of the 2-dimensional (2D) genus. The radiative transfer of hydrogen- ionizing photons and ionization-rate equations are calculated in a suite of numerical simulations under various input parameters. The 2D genus is calculated from the mock 21-cm images of high-redshift universe. We construct the 2D genus curve by varying the threshold differential brightness temperature, and compare this to the 2D genus curve of the underlying density field. We find that (1) the 2D genus curve reflects the evolutionary track of cosmic reionization and (2) the 2D genus curve can discriminate between certain reionization scenarios and thus indirectly probe the properties of radiation-sources. Choosing the right beam shape of a radio antenna is found crucial for this analysis. Square Kilometre Array (SKA) is found to be a suitable apparatus for this analysis in terms of sensitivity, even though some deterioration of the data for this purpose is unavoidable under the planned size of the antenna core.

• 한국음향학회지
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• 제38권6호
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• pp.678-686
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• 2019

수중에서는 다중 경로로 인한 인접 심볼 간 간섭의 영향으로 통신 성능이 저하되며, 수동형 시역전 처리는 다중 경로를 완화하기 위한 가장 효율적인 기법이다. 수동형 시역전 처리의 성능을 향상시키기 위해 다이버시티 결합기법이 이용되고 있으며, 본 논문에서는 여러 각도로의 빔 조향을 통해 획득한 신호들을 결합하는 빔 다이버시티 결합기법을 이용하여 통신 성능을 분석하였다. 수직 선 배열 센서에 수신된 탐침 신호로부터 추정한 빔-시간 그래프를 통해 음파의 전달 각도들을 추정하였으며, 추정된 각도 중 결합 개수 및 방식에 따른 통신 성능을 분석하였다. 분석을 위해 2018년 10월 포항 동방 해역에서 수행된 Biomimetic Long range Acoustic Communications 2018(BLAC18) 실험 데이터를 활용하였으며, 통신 성능 지표로써 출력 신호 대 잡음비를 이용하였다.

• 천문학논총
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• 제30권2호
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• pp.495-497
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• 2015

Galaxies can be "pre-processed" in the low-density outskirts by ambient medium in the filaments or tidal interactions with other galaxies while falling into the cluster. In order to probe how early on and by which mechanisms galaxies can be affected before they enter high-density cluster environments, we are carrying out an atomic hydrogen ($H\small{I}$) imaging study of a sample of galaxies selected from three filamentary structures around the Virgo cluster. Our sample consists of 14 late-type galaxies, which are potentially interacting with their surroundings. The $H\small{I}$ observations have been done using the Westerbork Synthesis Radio Telescope, the Giant Metrewave Radio Telescope, and the Jansky Very Large Array with column density sensitivity of ${\approx}3-5{\times}10^{19}cm^{-2}$ in $3{\sigma}$ per channel, which is low enough to detect faint $H\small{I}$ features in the outer disks of galaxies. In this work, we present the Hi data of two galaxies that were observed with GMRT. We examine the $H\small{I}$ morphology and kinematics to find the evidence for gas-gas and/or tidal interactions, and discuss which mechanism(s) could be responsible for pre-processing in these cases.

• Clinical and Experimental Reproductive Medicine
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• 제38권2호
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• pp.68-74
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• 2011

Objective: Previously, we found that oocyte specific homeobox (Obox) 4 plays significant role in completion of meiosis specifically at meiosis I-meiosis II (MI-MII) transition. The purpose of this study was to determine the mechanism of action of $Obox4$ in oocyte maturation by evaluating downstream signal networking. Methods: The $Obox4$ dsRNA was prepared by $in$ $vitro$ transcription and microinjected into the cytoplasm of germinal vesicle oocytes followed by $in$ $vitro$ maturation in the presence or absence of 0.2 mM 3-isobutyl-1-metyl-xanthine. Total RNA was extracted from 200 oocytes of each group using a PicoPure RNA isolation kit then amplified two-rounds. The probe hybridization and data analysis were used by Affymetrix Gene-Chip$^{(R)}$ Mouse Genome 430 2.0 array and GenPlex 3.0 (ISTECH, Korea) software, respectively. Results: Total 424 genes were up (n=80) and down (n=344) regulated after $Obox4$ RNA interference (RNAi). Genes mainly related to metabolic pathways and mitogen-activated protein kinase (MAPK) signaling pathway was changed. Among the protein kinase C (PKC) isoforms, PKC-alpha, beta, gamma were down-regulated and especially the MAPK signaling pathway PKC-gamma was dramatically decreased by $Obox4$ RNAi. In the cell cycle pathway, we evaluated the expression of genes involved in regulation of chromosome separation, and found that these genes were down-regulated. It may cause the aberrant chromosome segregation during MI-MII transition. Conclusion: From the results of this study, it is concluded that $Obox4$ is important upstream regulator of the PKC and anaphase-promoting complex action for maintaining intact germinal vesicle.

• 생명과학회지
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• 제21권9호
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• pp.1205-1213
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• 2011

재조합 균주인 E. coli JM109/DL-3를 사용하여 carboxymethylcellulase를 생산하기 위한 배지의 최적 염 농도를 orthogonal array method (OAM)과 response surface method (RSM) 등과 같은 통계학적인 방법으로 확립하고 그 결과를 비교하였다. OAM에 기초를 한 Qualitek-4 Software를 사용하여 실험을 계획하고, 그 결과를 분석한 결과는 K2HPO4가 균체의 생장 및 carboxymethylcellulase의 생산에 미치는 영향이 가장 크다는 사실을 확인하였다. 균체의 생육에 최적인 $K_2HPO_4$, NaCl, $MgSO_4{\cdot}7H_2O$ 및 $(NH_4)_2SO_4$의 농도는 10.0, 1.0, 0.2 및 0.6 g/l이었으나, carboxymethylcellulase의 생산에 최적인 각 염들의 농도는 각각 5.0, 1.0, 0.4 및 0.6 g/l이었다. RSM에 기초를 한 Design-Expert Software를 사용하여 실험을 계획하고, 그 결과를 분석한 결과는 $K_2HPO_4$가 균체의 생장 및 carboxymethylcellulase의 생산에 가장 중요한 인자라는 사실을 확인하였다. 균체의 생장에 최적인 $K_2HPO_4$, NaCl, $MgSO_4{\cdot}7H_2O$ 및 $(NH_4)_2SO_4$의 농도는 7.44, 1.08, 0.22 및 0.88 g/l이었으나, carboxymethylcellulase의 생산에 최적인 각 염들의 농도는 각각 5.84, 0.69, 0.28 및 0.54 g/l이었다. 기본적으로 OAM에 기초한 software를 사용하여 얻은 결과는 RSM에 기초한 software를 사용하여 얻은 결과와 유사하였다. 최적 조건에서 재조합 균주 E.coli JM109/DL-3이 생산하는 carboxymethylcellulase의 생산은 B. amyloliquifacience DL-에 비하여 1.92배 증가하였다.

• 천문학회보
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• 제40권1호
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• pp.73.2-74
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• 2015

The gas cloud G2 falling toward Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, is supposed to provide valuable information on the physics of accretion flows and the environment of the black hole. We observed Sgr A* with four European stations of the Global Millimeter Very Long Baseline Interferometry Array (GMVA) at 86 GHz on 1 October 2013 when parts of G2 had already passed the pericenter. We searched for possible transient asymmetric structure - such as jets or winds from hot accretion flows - around Sgr A* caused by accretion of material from G2. The interferometric closure phases (which are zero if the spatial brightness distribution of the target is symmetric, and deviate from zero otherwise) remained zero within errors during the observation time. We thus conclude that Sgr A* did not show significant asymmetric (in the observer frame) outflows in late 2013. Using simulations, we constrain the size of the outflows that we could have missed to ${\approx}2.5$ mas along the major axis, ${\approx}0.4$ mas along the minor axis of the beam, corresponding to approximately 232 and 35 Schwarzschild radii, respectively; we thus probe spatial scales on which the jets of radio galaxies are suspected to convert magnetic into kinetic energy. As probably less than 0.2 Jy of the flux from Sgr A* can be attributed to accretion from G2, one finds an effective accretion rate ${\eta}M{\leq}1.5{\times}10^9kg/s{\approx}7.7{\times}10^{-9}M_{earth}/yr$ for material from G2. Exploiting the kinetic jet power-accretion power relation of radio galaxies, one finds that the rate of accretion of matter that ends up in jets is limited to $M{\leq}10^{17}kg/s{\approx}0.5M_{Earth}/yr$ less than about 20% of the mass of G2. Accordingly, G2 appears to be largely stable against loss of angular momentum and subsequent (partial) accretion at least on time scales ${\leq}1$ year.