• 한국식품영양과학회지
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• 제41권9호
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• pp.1301-1304
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• 2012

국내산 정제염, 천일염과 죽염(9회)의 pH, 무기질 성분, OH기 함량, 환원력과 DPPH 활성산소 소거 효과를 측정하였다. pH 측정에서 정제염은 약간 산성이고 천일염은 알칼리성을 나타내었고 죽염은 천일염보다 더 높은 알칼리성을 나타내었다. 미네랄 함량은 죽염의 Ca, Fe, Mn, P, S, K 함량이 정제염과 천일염보다 더 많았다. 특히 Fe은 죽염만 함유하고 K의 함량도 다른 소금보다 많이 함유하였다. FT-IR을 이용한 실험에서 OH기 함량도 죽염은 정제염과 천일염보다더 많았고 peak에 따라 정제염은 6.5배, 천일염과는 2.3배의차이가 있었다. Bioanalytical system을 이용한 소금 수용액에서 죽염의 전위 환원력은 정제염과 천일염보다 더 크게 높았다. 1~25% 농도에서 소금의 DPPH 항산화실험에서 죽염의 활성산소 소거 능력이 가장 강하게 나타났고 정제염과 천일염은 농도 증가에 따라 항산화 효과가 큰 차이가 없었다. 25% 고농도에서 정제염과 천일염의 산소 소거 기능이죽염과 16배의 차이가 나타났다. 이상의 결과로부터 죽염은 알칼리성을 띄는 소금이고 OH기 함량과 전위 환원력도 일반소금보다 현저히 높았다. 또한 이들의 화학적인 특성을 가진 죽염은 항산화 효능도 일반소금보다 크게 높았다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.77.2-77.2
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• 2013

In this talk, I will briefly review recent results of my group related to application of atomic layer deposition (ALD) for fabricating environmental catalysts and organic solar cells. ALD was used for preparing thin films of TiO2 and NiO on mesporous silica with a mean pore size of 15 nm. Upon depositing TiO2 thin films of TiO2 using ALD, the mesoporous structure of the silica substrate was preserved to some extent. We show that efficiency for removing toluene by adsorption and catalytic oxidation is dependent of mean thickness of TiO2 deposited on silica, i.e., fine tuning of the thickness of thin film using ALD can be beneficial for preparing high-performing adsorbents and oxidation catalysts of volatile organic compound. NiO/silica system prepared by ALD was used for catalysts of chemical conversion of CO2. Here, NiO nanoparticles are well dispersed on silica and confiend in the pore, showing high catalytic activity and stability at 800oC for CO2 reforming of methane reaction. We also used ALD for surface modulation of buffer layers of organic solar cell. TiO2 and ZnO thin films were deposited on wet-chemically prepared ZnO ripple structures, and thin films with mean thickness of ~2 nm showed highest power conversion efficiency of organic solar cell. Moreover, performance of ALD-prepared organic solar cells were shown to be more stable than those without ALD. Thin films of oxides deposited on ZnO ripple buffer layer could heal defect sites of ZnO, which can act as recombination center of electrons and holes.

• 대한금속재료학회지
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• 제50권2호
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• pp.159-163
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• 2012

A TCO-less ruthenium (Ru) catalytic layer on glass substrate instead of conventional Ru/TCO/ glass substrate was assessed as counter electrode (CE) material in dye sensitized solar cells (DSSCs) by examining the effect of the Ru thickness on the DSSC performance. Ru films with different thicknesses (34, 46, 69, and 90 nm) were deposited by atomic layer deposition (ALD) on glass substrates to replace both existing catalyst and electrode layer. In order to make our comparison, we also prepared an Ru catalytic layer by a similar method on FTO/glass substrate. Finally, we prepared the $0.45cm^2$ DSSC device the properties of the DSSCs were examined by cyclic voltammetry (CV), impedance spectroscopy (EIS), and current-voltage (I-V) method. CV measurements revealed an increase in catalytic activity with increasing film thickness. The charge transfer resistance at the interface between the electrolyte and Rudecreased with increasing Ru thickness. I-V results showed that the energy conversion efficiency increased up to 1.96%. Our results imply that TCO-less Ru/glass might perform as both catalyst and electrode layer when it is used in counter electrodes in DSSCs.

• Journal of Astronomy and Space Sciences
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• 제21권4호
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• pp.441-452
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• 2004

실시간 관측자료를 사용하여 현재상태를 진단하고 이후의 변화를 예보하는 것은 우주환경 모니터링 시스템의 필수적인 요소라 할 수 있다. 본 연구에서는 ION(IDL On the Net)을 이용하여 웹 기반의 우주환경모니터링 시스템을 구축하였다(http://sun.kao.re.kr). 이 웹 페이지에서는 현재의 태양 및 지자기 데이터를 보여주고 위성, 통신, 지상 전력시스템에 줄 수 있는 영향을 예측하여 제시하고 있다. 그리고 NOAA/SEC에서 매일 제시하는 태양 X선 플레어, 프로톤 현상, 지자기 폭풍의 예보결과를 표시한다. 또한 행성간 태양 충격파와 CME(Coronal Mass Ejection; 코로나 물질 방출)의 지구도달 시간을 예측하기 위해 두 가지의 예측모델이 웹에서 구동되도록 하였다. 현재 우리는 여러가지 태양 및 지자기 활동과 관련된 각종데이터를 IDL과 FTP 프로그램을 사용하여 실시간으로 다운받아 우주환경 데이터베이스를 확장하고 있다. 본 논문에서는 한국천문연구원의 우주환경모니터링시스템 개발에 관하여 자세히 기술한다.

• 천문학회지
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• 제56권2호
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• pp.263-275
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• 2023

The Sun-Earth Lagrange point L4 is considered as one of the unique places where the solar activity and heliospheric environment can be observed in a continuous and comprehensive manner. The L4 mission affords a clear and wide-angle view of the Sun-Earth line for the study of the Sun-Earth and Sun-Moon connections from he perspective of remote-sensing observations. In-situ measurements of the solar radiation, solar wind, and heliospheric magnetic field are critical components necessary for monitoring and forecasting the radiation environment as it relates to the issue of safe human exploration of the Moon and Mars. A dust detector on the ram side of the spacecraft allows for an unprecedented detection of local dust and its interactions with the heliosphere. The purpose of the present paper is to emphasize the importance of L4 observations as well as to outline a strategy for the planned L4 mission with remote and in-situ payloads onboard a Korean spacecraft. It is expected that the Korean L4 mission can significantly contribute to improving the space weather forecasting capability by enhancing the understanding of heliosphere through comprehensive and coordinated observations of the heliosphere at multi-points with other existing or planned L1 and L5 missions.

• 천문학논총
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• 제15권spc1호
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• pp.93-102
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• 2000

We have reviewed the magnetic activity in close binaries. Solar like magnetic activity indicators such as photometric spots, chromo spheric emission, coronal X-ray and radio emission, and flare activity are commonplace in many cool stars with convective envelopes. Using the UV spectra we confirmed the strength of stellar activity increases with more rapid rotation and later spectral types which corresponds to the increasing depth of the star's convective envelope. Apart from very young stellar objects such as T Tauri stars, the stars with the highest levels of activity are close binary systems composed of cool stars, i.e., the chromospherically active binaries such as RS CVn, BY Dra, W UMa and related systems. The IUE low and high dispersion spectra of V711 Tau, VW Cep and SW Lac are used for ultraviolet photometry and for a variation study of chromospheric activity. Evidence of chromospherically activity is indicated by the intensity variation of the Mg II emission line with orbital phase.

• 한국응용과학기술학회지
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• 제24권1호
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• pp.1-9
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• 2007

It prepared the $TiO_2$ powder which has photo-catalytic activity in the visible-light by the wet process with titanium oxysulfate. The titanium $dioxide(TiO_2)$ by the wet process creates a new absorption band in the visible light region, and is expected to create photocatalytic activity in this region. Anatase $TiO_2$ powder which has photocatalytic activity in the visible light region, is treated using microwave and radio-frequency(RF) plasma. But, the $TiO_2$ powder for the visible light region, which also can be easily produced by wet process. The wet process $TiO_2$ absorbed visible light between 400nm and 600nm, and showed a high activity in this region, as measured by the oxidation removal of aceton from the gas phase. The AH-380 sample appears the yellow color to be strong, the catalytic activity in the visible ray was excellent in comparison with the plasma-treated $TiO_2$. The AH-380 $TiO_2$ powder, which can be easily produced on a large scale, is expected to have higher efficiency in utilizing solar energy than the plasma-treated $TiO_2$ powder.

• 천문학회보
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• 제40권1호
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• pp.64.3-64.3
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• 2015

We have developed a set of daily solar flare peak flux forecast models for strong flares using multiple linear regression and artificial neural network methods. We consider input parameters as solar activity data from January 1996 to December 2013 such as sunspot area, X-ray flare peak flux and weighted total flux of previous day, and mean flare rates of McIntosh sunspot group (Zpc) and Mount Wilson magnetic classification. For a training data set, we use the same number of 61 events for each C-, M-, and X-class from Jan. 1996 to Dec. 2004, while other previous models use all flares. For a testing data set, we use all flares from Jan. 2005 to Nov. 2013. The best three parameters related to the observed flare peak flux are weighted total flare flux of previous day (r = 0.51), X-ray flare peak flux (r = 0.48), and Mount Wilson magnetic classification (r = 0.47). A comparison between our neural network models and the previous models based on Heidke Skill Score (HSS) shows that our model for X-class flare is much better than the models and that for M-class flares is similar to them. Since all input parameters for our models are easily available, the models can be operated steadily and automatically in near-real time for space weather service.

• Journal of Astronomy and Space Sciences
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• 제34권2호
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• pp.119-125
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• 2017

We retrieved rotational temperatures from emission lines of the OH airglow (8-3) band in the sky spectra of the Sloan digital sky survey (SDSS) for the period 2000-2014, as part of the astronomical observation project conducted at the Apache Point observatory ($32^{\circ}N$, $105^{\circ}W$). The SDSS temperatures show a typical seasonal variation of mesospheric temperature: low in summer and high in winter. We find that the temperatures respond to solar activity by as much as $1.2K{\pm}0.8K$ per 100 solar flux units, which is consistent with other studies in mid-latitude regions. After the seasonal variation and solar response were subtracted, the SDSS temperature is fairly constant over the 15 year period, unlike cooling trends suggested by some studies. This temperature analysis using SDSS spectra is a unique contribution to the global monitoring of climate change because the SDSS project was established for astronomical purposes and is independent from climate studies. The SDSS temperatures are also compared with mesospheric temperatures measured by the microwave limb sounder (MLS) instrument on board the Aura satellite and the differences are discussed.

• Bulletin of the Korean Chemical Society
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• 제34권3호
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• pp.831-836
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• 2013

Platinized counter electrode is common in most of the dye sensitized solar cell (DSSC) researches because of its high catalytic activity and corrosion stability against iodine in the electrolyte. Platinum (Pt) film coating on fluorine doped tin oxide (FTO) glass surface by using alcoholic solution of hexachloroplatinic acid ($H_2PtCl_6$), paste containing Pt precursors or sputtering are widely used techniques. This paper presents a novel application of Pt ink containing nanoparticles for making platinized counter electrode for DSSC. The characteristics of Pt films coated on FTO glass surface by different chemical methods were compared along with the performance parameters of the DSSCs made by using the films as counter electrodes. The samples coated with Pt inks were sintered at $300^{\circ}C$ for 30 minutes whereas Pt-film and Pt-paste were sintered at $400^{\circ}C$ for 30 minutes. The Pt ink diluted in n-hexane was found to a promising candidate for the preparation of platinized counter electrode. The ink may also be applicable for DSSC on flexible substrates after optimization its sintering temperature.