• The Korean Journal of Pesticide Science
• /
• v.5 no.3
• /
• pp.26-35
• /
• 2001

In order to search potent antifungal substances from domestic plants, 40 plants cultivated in Korea were collected. After extracting with methanol (MeOH) and concentrating to dryness, the MeOH extracts were screened for in vivo antifungal activity against six plant diseases at a concentration of $2000{\mu}g/mL$. Fourteen extracts showed disease-controlling activity more than 90% against at least one of the 6 plant diseases tested; eight, seven, and three extracts controlled more than 90% the development of rice blast, tomato late blight, and wheat leaf rust, respectively. However, none of the extracts exhibited in vivo antifungal activity more than 90% against rice sheath blight, tomato gray mold, and barley powdery mildew. From the MeOH extracts of Angelica gigas and A. dahurica showing potent controlling activity against rice blast, 1 and 2 antifungal substances, respectively, were isolated by solvent partitioning and column chromatography. The three compounds were identified to be coumarins, namely, decursin, imperatorin, and isoimperatorin, by mass spectrometry and NMR spectroscopy. They were examined for in vitro and in vivo antifungal activities together with umbelliferone (7-bydroxycournarin) and scopoletin (6-methoxy-7-hydroxycoumarin) containing a free hydroxyl group at position 7 to investigate the structure-activity relationship. In vitro, most of 50% growth inhibitory concentrations ($IC_{50}$) were over $200{\mu}g/mL$, indicating that they have relatively weak antifungal activity. The antifungal activity of decursin and scopoletin, containing cyclic alkoxy groups instead of free hydroxyl group at position 7, was stronger than umbelliferone and scopoletin. Especially, decursin and imperatorin showed potent antifungal activities against Pythium ultimum and Magnaporthe grisea, respectively, with $IC_{50}$ values less than $25{\mu}g/mL$. In vivo, decursin and imperatorin showed potent antifungal activity against rice blast, whereas other coumarins hardly controlled the development of 6 plant diseases tested. These results suggest that the antifungal activity of 7-hydroxycoumarin derivative is substantially increased when the hydroxyl group at position 7 is protected by a stable cyclic alkoxy grouping.

• Journal of the Korean earth science society
• /
• v.28 no.7
• /
• pp.847-856
• /
• 2007

The Planetary nebula NGC 6881 displays quadrupole morphology and it also has a jet feature in its image. We investigated the line profiles of the optical region spectral emission lines, using the Hamilton Echelle Spectrograph (HES) at the Lick observatory. The HES data obtained in this study was the radiation coming from the inner region within the diameter of 4 second of arc. Expansion velocity was obtained, based on the strong emission line profiles of e.g. H, Hel, Hell, [OIII], [NII], [ArIII], [SII], and [SIII}, using the IRAF and StarLink/Dipso reduction packages. The HI recombination lines showed one single peak profile, while the He and forbidden strong lines displayed double peaks. The results of this study show that the outflow velocity of gas increases radially outwards due to the central stellar radiation pressure. It was concluded that three central rings appeared in the HST image are the result of a combined structure of bipolar cones (seen in e.g. HI lines) and a ring (seen in He, [SIII] lines) in projection.

• Bulletin of the Korean Space Science Society
• /
• 2003.10a
• /
• pp.52-52
• /
• 2003

1996년 미국 버클리 대학의 Space Science Laboratory와 공동으로 고온 성간 물질의 관측에 대한 Conceptual Study로부터 시작되어 1998년 과학위성 1호의 주 탑재체로 선정되면서 본격적인 개발에 들어간 원자외선 분광기(FIMS: Far-ultraviolet IMaging Spectrograph)는 Engineering Model 개발, Qualification Model 개발, Flight Model의 개발 및 보정, 그리고 최종적으로 과학기술위성 1호 본체와의 조립 시험 및 환경시험을 거쳐 2003년 9월 26일 러시아의 플레세츠크에서 COSMOS-3M 발사체에 의해 발사된다. FIMS를 포함한 과학위성 1호는 현재 발사를 위해 러시아 현지에 이송되어 최종 시험을 진행 중이며, 발사 후 약 20일 가량은 위성의 운용 시험을 하게 되며, 이후 FIMS의 운용에 영향을 줄 수 있는 Out-gassing이 충분히 이루어진 후 FIMS의 Test 및 초기 운용이 이루어 진다. FIMS의 Detector로 사용되는 MCP(Micro Channel Plate)의 정상적 동작이 확인되면, 1년여에 걸쳐 FIMS의 주 임무인 원자외선 영역(900∼1750')의 은하계 전천 탐사를 수행하게 된다. 전천 탐사가 마무리 되면, 전천탐사의 결과를 바탕으로 개별 천체의 영상 및 분광 자료를 획득하게 되며, 동시에 원자외선 영역의 오로라 및 지구 대기광 측정을 수행한다.

• Journal of the Korean earth science society
• /
• v.31 no.4
• /
• pp.370-377
• /
• 2010

In this study, we investigated the kinematical properties of the L1521F-IRS in Taurus region using HCN (J=1-0) molecular line. The high resolution mapping has carried out by $5{\times}5$ point observations covering $3.7'{\times}3.7'$ area using a 12-m telescope of Arizona Radio Observatory in Tucsan, USA. L1521F which harbors the faint infrared L1521F-IRS, displayed a strong central concentration of integrated intensity in HCN without serious molecular depletion. It showed a symmetric kinematical structure with the opposite infall motion in either side of the central cores. It is a direct evidence of bipolar outflows in the core of L1521F.

• Korean journal of applied entomology
• /
• v.57 no.3
• /
• pp.199-207
• /
• 2018

Miticidal and repellent activity of twenty plant essential oils against the adults of two spotted spider mites, Tetranychus urticae, were examined. Sandal wood oil was the most potent one in mortality, whereas clary sage oil exhibited the greatest repellent activity. On those twenty essential oils tested, no apparent correlation between toxicity and repellency was observed. When the most active oils were blended, the combinations tend to exhibit antagonistic interactions in both toxicity and repellent activity. The chemical compositions of sandal wood oil and clary sage oil were identified via GC/MS analyses, and the major constituents of sandal wood oils were sesquiterpene compounds, whereas the major ones for clary sage oil were monoterpenes. Among the major components in clary sage oil, linalyl acetate was not only the most abundant constituent, but also the most responsible one for its repellent activity.

• Journal of the Korean earth science society
• /
• v.38 no.1
• /
• pp.1-10
• /
• 2017

The symbiotic star AG Peg is a nebulous binary system that consists of giant star (GS) and white dwarf (WD). We investigated the HI Balmer emission lines of the symbiotic nova AG Peg, observed in 1998, 2001, and 2002 at Lick Observatory. The $H{\alpha}$ and $H{\beta}$ line profiles consist of blue-shifted, red-shifted, and broad components of which intensities and width showed notable changes. The HI emission line profiles that represent the kinematics of the gaseous nebula appear to be mainly from an accretion disk in relatively large radius from the WD. Considering the line of an observer's sight, both GS and WD are located at the sky plane side by side during the 1998 observation, while the WD is in front of GS during 2002 but the WD in rear during 2001. Such a relative position and the spectral line intensity variation imply that a fairly constant outflow occurs into WD from GS which caused to maintain the rotating thick accretion disk structure responsible for the observed spectral lines.

• Applied Biological Chemistry
• /
• v.28 no.4
• /
• pp.271-277
• /
• 1985

A polarograph with specially designed cell compartment usable in kinetic study of the mitochondrial respiration of a small sized sample was made, and its performance and experimental conditions were examined. An applied potential (ca-1.2V vs. SCE) which gives rise to the second step reduction of oxygen caused a considerable level of a residual current independent of oxygen, which is temporarily interpreted as the reduction current of the membrane-bound redox material(s) of mitochondria. A potential corresponding to the first slop reduction of oxygen (ca-0.4V vs SCE) did not produce the residual current. Thus, it is suggested that a measurement of oxygen concentration in a sample of mitochondria and submitochondrial particles by using dropping mercury electrode should be done with an applied potential of about -0.4V vs SCE. Consumption of oxygen by mitochondria was observed to follow practically zero order kinetics. Its rate constant exhibited the proportional relationship with the respiratory activity of mitochondria. Usefulness of tile instrument was properly demonstrated in the work on the temperature effect on the respiration of mitochondria isolated from several plant 4issues which were selected on the basis of chilling susceptivity.

• Journal of the Korean earth science society
• /
• v.23 no.4
• /
• pp.357-368
• /
• 2002

In this study we have tried to explain the barrel-shaped morphology for young supernova remnants considering the dynamical effects of the ejecta. We consider the magnetic field amplification resulting from the Rayleigh-Taylor instability near the contact discontinuity. We can generate the synthetic radio image assuming the cosmic-ray pressure and calculate the azimuthal intensity ratio (A) to enable a quantitative comparison with observations. The postshock magnetic field are amplified by shearing, stretching, and compressing at the R-T finger boundary. The evolution of the instability strongly depends on the deceleration of the ejecta and the evolutionary stage of the remnant. the strength of the magnetic field increases in the initial phase and decreases after the reverse shock passes the constant density region of the ejecta. However, some memory of the earlier phases of amplification is retained in the interior even when the outer regions turn into a blast wave. The ratio of the averaged magnetic field strength at the equator to the one at the pole in the turbulent region can amount to 7.5 at the peak. The magnetic field amplification can make the large azimuthal intensity ratio (A=15). The magnitude of the amplification is sensitive to numerical resolution. This mens the magnetic field amplification can explain the barrel-shaped morphology of young supernova remnant without the dependence of the efficiency of the cosmic-ray acceleration on the magnetic field configuration. In order for this mechanism to be effective, the surrounding magnetic field must be well-ordered. The small number of barrel-shaped remnants may indicate that this condition rarely occurs.

• Applied Chemistry for Engineering
• /
• v.9 no.3
• /
• pp.377-382
• /
• 1998

This study was carried out to investigate the relation between surface acidity and interfacial electrical characteristics of surface-treated ${\gamma}-alumina$ whose surface activity was increased. The points of zero charge (P. Z. C.) of ${\gamma}-alumina$ whose surface is treated with the sulfuric, nitric and hydro-chloric acid of various concentration were measured from the site-binding theory and mass transport method. The surface active sites were measured by amine titration method and Hammett indicator method. The interfacial properties at alumina/KCl(aq) interface were measured by potentiometric titration. From the experimental results, the following results were obtained. Pure ${\gamma}-alumina$ surface acidity decreases with the increase of calcination temperature at strength $H_o{\leq}+9.3$ Surface-treated alumina acidic properties increase with the anion loading on alumina surface. The surface ionization constants decrease with anion loading on alumina surface, then P. Z. C. decreases with acid amount on alumina surface. Acid amount of surface treated alumina can be correlated with surface charge density at strength $H_o{\leq}+4.8$ as follows. $SO_4^2-/Al_2O_3:Q_A=-0.172ln(0.0418{\sigma}+1.448)$ $NO_3^-/Al_2O_3:Q_A=-0.024{\sigma}-0.0189$ $Cl^-/Al_2O_3:Q_A=-0.01{\sigma}-0.2006$.

• Journal of Korea Water Resources Association
• /
• v.51 no.2
• /
• pp.151-163
• /
• 2018

The objective of this study was to estimate LOADEST (LOAD Estimator) coefficients for simulating pollutant loads in ungauged watersheds. Regression models of LOADEST were used to simulate pollutant loads, and the multiple linear regression (MLR) was used for coefficients estimation on watershed characteristics. The fifth and third model of LOADEST were selected to simulate T-N (Total-Nitrogen) and T-P (Total-Phosphorous) loads, respectively. The results and statistics indicated that regression models based on LOADEST simulated pollutant loads reasonably and model coefficients were reliable. However, the results also indicated that LOADEST underestimated pollutant loads and had a bias. For this reason, simulated loads were corrected the bias by a quantile mapping method in this study. Corrected loads indicated that the bias correction was effective. Using multiple regression analysis, a coefficient estimation methods according to the watershed characteristic were developed. Coefficients which calculated by MLR were used in models. The simulated result and statistics indicated that MLR estimated the model coefficients reasonably. Regression models developed in this study would help simulate pollutant loads for ungauged watersheds and be a screen model for policy decision.