• 공업화학
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• 제27권1호
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• pp.45-49
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• 2016

과량의 GO 및 poly(4-styrene sulfonate) (PSS)의 존재 하에서 산화제 없이 3,4-ethylenedioxythiophene (EDOT)의 in-situ 중합 반응을 시도하였다. 반응물(GO-P)의 XPS, FT-IR 등의 분석을 통하여 산화제 없이도 모노머인 EDOT의 산화중합이 원활하게 진행되어 PEDOT/PSS가 합성되고 GO와 복합화된 것을 확인할 수 있었다. GO-P는 수분산성은 우수하였으나, 전기적 절연체인 GO가 42% 포함되어 있으므로 전기전도도는 $15S{\cdot}m^{-1}$로 매우 낮았다. 그러나 GO-P 필름을 $200^{\circ}C$에서 8 h 열처리하면 GO의 일부분이 환원되면서 전도도가 $212S{\cdot}m^{-1}$까지 향상되었다.

• 전자공학회논문지
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• 제52권2호
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• pp.106-111
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• 2015

일반적으로 기준전압 생성기는 쌍안정성을 가지므로 이를 올바른 상태에서 동작시키기 위해서는 적절한 시동회로가 필요하다. 본 논문에서는 저전압 기준전압 발생기를 위한 새로운 시동회로를 제안한다. 제안한 시동회로는 기준전압발생기의 상태를 결정하기 위하여 기준전압 발생기의 BJT에 흐르는 전류를 측정한다. 기준전압발생기가 올바른 상태에 있을 때 이 전류가 가지는 값은 잘 정의되므로 이를 통하여 회로의 상태를 신뢰성 있게 결정할 수 있다. 전류는 내부에 오프셋 전압을 갖는 비교기를 이용하여 측정하였다. 130nm CMOS 공정을 이용하여 설계를 하였으며, 레이아웃에서 추출한 기생 성분을 포함하는 Monte-Carlo 시뮬레이션을 통해 회로의 성능을 검증 하였다. 제안된 시동회로를 사용하는 기준전압발생기에 850mV 이상의 전원 전압이 가해질 경우, 소자에 미스매치가 있더라도 안정적으로 기준전압 생성기가 시동하는 것을 확인하였다.

• 천문학논총
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• 제30권3호
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• pp.811-819
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• 2015

The e-CALLISTO is a network of CALLISTO (Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories) spectrometers which detect solar radio bursts 24 hours a day in frequency range 45-870 MHz. The number of channels per spectrum is 200 and the time resolution of whole spectrum is 0.25 second. The Korean e-CALLISTO station was developed by Korea Astronomy and Space Science Institute (KASI) collaborating with Swiss Federal Institute of Technology Zurich (ETH Zurich) since 2007. In this paper, we report replacement of the tracking mount and development of the control program using Visual C++/MFC. The program can make the tracking mount track the Sun and schedule CALLISTO to start and to finish its observation automatically using the Solar Position Algorithm (SPA). Daily tracking errors (RMSE) are 0.0028 degree in azimuthal axis and 0.0019 degree in elevational axis between 2014 January and 2015 July. We expect that the program can save time and labor to make the observations of solar activity for space weather monitoring, and improve CALLISTO data quality due to the stable and precise tracking methods.

• 식물조직배양학회지
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• 제21권2호
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• pp.99-103
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• 1994

비선택성 제초제인 bialaphos는 고등식물에 있어서 glutamine 합성을 억제하여 식물체를 고사 시키는 능력을 갖고 있다. 본 연구에서 acetylteansferase에 의해 encoding된 bialaphos 저항성 유전자(bar gene)는 세균(Pseudomonas sryngae pv tabaci)의 genomic DNA로부터 cloning된 것을 사용하였다. 수분시킨 담배의 화계에 일정한 시간별로 bar 유전자를 처리한 결과 수분 후 30-40시간 사이의 처리구 에서 형질전환 식물체가 가장 많이 얻어 졌다. 그러한 형질전환 식물체의 kanamycin과 bialaphos 저항성 형질은 자식후대(T$_1$, T$_2$)에 있어서도 우성형질로 유전되었으나 wild type의 담배는 상기의 약제를 처리 하였을때 전부 고사하였다. 그리고, T$_1$세대의 형질전환 식물체로부터 전 염색체 DNA를 추출하여 Southern 분석한 결과 bar 유전자가 식물의 염색체상에 안정하게 존재하는 것을 확인하였다. 이상의 결과로부터 담배의 수분, 수정 시기에 외부유전자인 bar를 화주에 처리함으로써 bialaphos 저항성 식물을 만들어낼 수 있었다.

• 한국수산과학회지
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• 제43권6호
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• pp.642-647
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• 2010

This study examined the antimicrobial activity of Myagropsis yendoi (MY). The antimicrobial activity of ethanol and aqueous MY extracts were measured using a paper disc assay. The MY ethanol extract had the best antimicrobial activity. It inhibited the growth of Candida tropicalis and Gram-positive bacteria such as Bacillus subtilis, Listeria innocua, L. monocytogenes, and Staphylococcus aureus at 4 mg/mL. The minimum inhibitory concentration (MIC) of the MY ethanol extract ranged from 0.1 to 0.5%. The MY ethanol extract inhibited the growth of B. subtilis and L. innocuaat concentrations of 0.15% and 0.1%, respectively. The antimicrobial activity of the MY ethanol extract was not affected by heating at $121^{\circ}C$ for 15 min or pH 2.10. Therefore, the main substances responsible for the antimicrobial activity of the MY ethanol extract are believed to be stable with changing heat and pH.

• 한국미생물·생명공학회지
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• 제1권1호
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• pp.37-42
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• 1973

본실험에서 얻어진 결과를 요약하면 다음과 같다. 1) Inulin을 분해하는 효소를 생산하는 Aspergillus속 1주를 선별하였다. 2) 선별된 묘주효소의 E.P차에 의한 침전은 pH8~5에서 효소단백질이 다량 회수되었다. 3) 선별된 묘주가 분비하는 Inulase활성최적 pH는 3.0부근이 었다. 4) 선별된 묘주의 Inulin 분해효소의 활성최적 온도는 $55^{\circ}C$였다. 5) 본 Sample효소의 열에 대한 안정성은 $50^{\circ}C$에서 10분간 열처리 하여도 안정하였다. 6) 본 Sample효소의 안정 pH는 2.5~4.5정도였다. 7) 본 Sample효소의 금속 ion에 대한 영향은 $Mg^{++}$는 Activator였으며 $Sb^{+++}$, $Bi^{+++}$.는 저농도에서는 inhibitor였으나 $10^{-4}$ M~$10^{-4}$ M 농도일때는 촉진시켰으며 더욱 금속 ion농도가 높아짐에 따라 inhibition하였으며 $Ag^{++}$, $Hg^{++}$의 경우에는 저농도($10^{-8}$ M)일 때는 Activation하였고 반면, 농도가 높아짐에 따라 저해효과가 더욱 컸으며 특히 $Hg^{++}$의 경우 $10^{-2}$ M 농도에서 약 80% 저해를 나타내었다.내었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권5호
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• pp.859-876
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• 2010

In this paper, we propose a hierarchical application traffic classification system as an alternative means to overcome the limitations of the port number and payload based methodologies, which are traditionally considered traffic classification methods. The proposed system is a new classification model that hierarchically combines a binary classifier SVM and Support Vector Data Descriptions (SVDDs). The proposed system selects an optimal attribute subset from the bi-directional traffic flows generated by our traffic analysis system (KU-MON) that enables real-time collection and analysis of campus traffic. The system is composed of three layers: The first layer is a binary classifier SVM that performs rapid classification between P2P and non-P2P traffic. The second layer classifies P2P traffic into file-sharing, messenger and TV, based on three SVDDs. The third layer performs specialized classification of all individual application traffic types. Since the proposed system enables both coarse- and fine-grained classification, it can guarantee efficient resource management, such as a stable network environment, seamless bandwidth guarantee and appropriate QoS. Moreover, even when a new application emerges, it can be easily adapted for incremental updating and scaling. Only additional training for the new part of the application traffic is needed instead of retraining the entire system. The performance of the proposed system is validated via experiments which confirm that its recall and precision measures are satisfactory.

• Carbon letters
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• 제21권
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• pp.33-50
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• 2017

In this study, Fe-Ni bimetallic catalyst supported on kaolin is prepared by a wet impregnation method. The effects of mass of kaolin support, pre-calcination time, pre-calcination temperature and stirring speed on catalyst yields are examined. Then, the optimal supported Fe-Ni catalyst is utilised to produce multi-walled carbon nanotubes (MWCNTs) using catalytic chemical vapour deposition (CCVD) method. The catalysts and MWCNTs prepared using the optimal conditions are characterized using high resolution transmission electron microscope (HRTEM), high-resolution scanning electron microscope (HRSEM), electron diffraction spectrometer (EDS), selected area electron diffraction (SAED), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and X-ray diffraction (XRD). The XRD/EDS patterns of the prepared catalyst confirm the formation of a purely crystalline ternary oxide ($NiFe_2O_4$). The statistical analysis of the variance demonstrates that the combined effects of the reaction temperature and acetylene flow rate predominantly influenced the MWCNT yield. The $N_2$ adsorption (BET) and TGA analyses reveal high surface areas and thermally stable MWCNTs. The HRTEM/HRSEM micrographs confirm the formation of tangled MWCNTs with a particle size of less than 62 nm. The XRD patterns of the MWCNTs reveal the formation of a typical graphitized carbon. This study establishes the production of MWCNTs from a bi-metallic catalyst supported on kaolin.

• 대한원격탐사학회지
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• 제38권1호
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• pp.83-101
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• 2022

Accurate atmospheric correction is essential for the analysis of land surface and environmental monitoring. Aerosol optical depth (AOD) information is particularly important in atmospheric correction because the radiation attenuation by Mie scattering makes the differences between the radiation calculated at the satellite sensor and the radiation measured at the land surface. Thus, it is necessary to use high-quality AOD data for an appropriate atmospheric correction of high-resolution satellite images. In this study, we examined the Second Simulation of a Satellite Signal in the Solar Spectrum (6S)-based atmospheric correction results for the Sentinel-2 images in South Korea using raster AOD (MODIS) and single-point AOD (AERONET). The 6S result was overall agreed with the Sentinel-2 level 2 data. Moreover, using raster AOD showed better performance than using single-point AOD. The atmospheric correction using the single-point AOD yielded some inappropriate values for forest and water pixels, where as the atmospheric correction using raster AOD produced stable and natural patterns in accordance with the land cover map. Also, the Sentinel-2 normalized difference vegetation index (NDVI) after the 6S correction had similar patterns to the up scaled drone NDVI, although Sentinel-2 NDVI had relatively low values. Also, the spatial distribution of both images seemed very similar for growing and harvest seasons. Future work will be necessary to make efforts for the gap-filling of AOD data and an accurate bi-directional reflectance distribution function (BRDF) model for high-resolution atmospheric correction. These methods can help improve the land surface monitoring using the future Compact Advanced Satellite 500 in South Korea.

• 드라이브 ㆍ 컨트롤
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• 제18권4호
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• pp.19-27
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• 2021

A bunker bed is a type of furniture that efficiently utilizes a narrow indoor space by having a high bed and using the empty space below as a living and storage space. The demand for multi-purpose furniture is increasing due to the recent increase in single-person households and wide-spread shared accommodation. According to the consumer research, one of the major drawbacks of a bunker bed was to get on and off the bed through a ladder or stairs. In order to overcome these problems, it was confirmed that the height adjustment function that can easily adjust the minimum and maximum heights of the bed was necessary. In this study, a height adjustable bunker bed was designed by using a gas spring that generates a repulsive force by the compressed gas inside. The design process consisted of the following three steps: Firstly, the hysteresis characteristics due to a friction and spring constant of a commercial gas spring were confirmed by measuring the repulsive force vs. compressed displacement. Secondly, requirements of the vertical lifting force exerted on the bed against gravity force were derived. Finally, the height-adjustable bed using the four-bar link mechanism was designed with 4 parameters so that the bed weight of 60-70 kgf could be adjusted to 800 mm in height by an affordable initial operation force. The performance was verified through prototype production and the results of vertical displacement and force to move were nearly the same as designed. In addition, an electrically operated height-adjustable bed was also designed with linear actuators and the performance was proved with the prototype.