Root knot nematode species, such as Meloidogyne hapla, M. incognita, M. arenaria and M. javanica are economically most notorious nematode pests, causing serious damage to the various crops throughout world. In this study, DNA sequence analyses of the D1-D3 expansion segments of the 28S gene in the ribosomal DNA were conducted to characterize genetic variation of the four Meloidogyne species obtained from Korea and United States. PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism), SCAR (Sequence Characterized Amplified Region) marker and RAPD (Random Amplification of Polymorphic DNA) also were used to develop the methods for exact and rapid species identification. In the sequence analysis of the D1-D3 expansion segments, only a few nucleotide sequence variation were detected among M. incognita, M. arenaria, and M. javanica, except for M. hapla. The PCR-RFLP analysis that involves amplification of the mitochondrial COII and lrRNA region yielded one distinct amplicon for M. hapla at 500 bp, enabling us to distinguish M. hapla from M. incognita, M. arenaria, M. javanica reproduced by obligate mitotic parthenogenesis. SCAR markers successfully identified the four root knot nematode species tested. We are under development of RAPD primers specific to the three root knot nematodes found in Korea.

Cryptic mealybug (CMB), Pseudococcus cryptus, is a serious scale pest on citrus, especially grown in plastic greenhouse on Jeju island, Korea. Binomial sampling plan was developed using the relationship between infested proportion of twig with less than T scales (pT) and mean density per twig (m) according to the empirical model ln(m)=α+βln(-ln(1-pT)). T was defined as tally threshold and set to 1, 2, 3, 4 and 5 scales per twig in this study. T=3 was the best tally threshold for estimating densities of CMB based on the precision of the model. Binomial model with T=3 provided reliable predictions of mean densities of CMB observed on commercial citrus orchards. The obtaining model was evaluated by resampling validation of Wald's sequential binomial plan and by fit at 95% confidence intervals for independent collected data sets. Binomial sampling program for decision-making of CMB population level was obtained at the action threshold 0.10, proportion of twig infested with more than 3 scales.

A new ion transport code for planetary ionospheric studies has been developed with consideration of velocity differences among ion species involving ion-ion collision. Most of previous planetary ionosphere models assumed that ions diffuse through non-moving ion and neutral background in order to consolidate continuity and momentum equations for ions into a simple set of diffusion equations. The simplification may result in unreliable density profiles of ions at high altitudes where ion velocities are fast and their velocity differences are significant enough to cause inaccuracy when computing ion-ion collision. A new code solves explicitly one-dimensional continuity and momentum equations for ion densities and velocities by utilizing divided Jacobian matrices in matrix inversion necessary to the Newton iteration procedure. The code has been applied to Martian nightside ionosphere models, as an example computation. The computed density profiles of O+, OH+, and HCO+ differ by more than a factor of 2 at altitudes higher than 200 km from a simple diffusion model, whereas the density profile of the dominant ion, O2+, changes little. Especially, the density profile of HCO+ is reduced by a factor of about 10 and its peak altitude is lowered by about 40 km relative to a simple diffusion model in which HCO+ ions are assumed to diffuse through non-moving ion background, O2+. The computed effects of the new code on the Martian nightside models are explained readily in terms of ion velocities that were solved together with ion densities, which were not available from diffusion models. The new code should thus be expected as a significantly improved tool for planetary ionosphere modelling.

강진을 고려한 지진설계 규준은 약진지역에서는 불필요한 경제적 손실을 가져을 수 있고, 지반-구조물 상호작용을 고려한 성능기준 설계가 합리적인 지진설계를 위해서 중요하다는 것이 인식되었다. 이 연구에서는 연약지반 위에 놓인 단자유도계의 탄성, 비탄성 지진응답 해석을 지반의 비선형성을 고려하여 최대지진가속도를 0.07g와 0.11g로 조정한 11개 약진에 대해 수행하였다. 지진응답해석은 지반-구조물체계에 대해 유사 3차원 동적해석 프로그램으로 암반에 지진기록을 입력하여 한 단계에 일괄적으로 수행하였다. 연구 결과에 의하면 고정지반이나 선형지반을 가정한 지진응답 스펙트럼은 구조물-지반체계의 실제적인 거동을 보여주지 못하는 것으로 나타났으며, 합리적인 지진설계를 위해서는 지진규준에 정해진 일상적인 설계절차에 다라서 수행하는 것보다 다른 성질을 가진 여러 지반에 대해서 성능기준 지진설계를 수행하는 것이 필요하다. 약진을 받는 연약지반의 비선형성도 입력지진동을 증폭시켜 탄성, 비탄성 지진응답 스펙트럼에 심하게 영향을 미쳤으며, 그 현상은 특히 탄성 응답스펙트럼에서 두드러졌다.

We have constructed a non-spherical model for the hot oxygen corona of Mars by including the effects of planetary rotation and diurnal variation of the Martian ionosphere. Exospheric oxygen densities are calculated by integrating ensemble of ballistic and escaping oxygen atoms from the exobase over the entire planet. The hot oxygen atoms are produced by dissociative recombination of O+2, the major ion in the Martian ionosphere. The densities of hot oxygen atoms at the exobase are estimated from electron densities which have been measured to vary with solar zenith angle. Our model shows that the density difference of hot oxygen atoms between noon and terminator is about two orders of magnitude near the exobase, but reduces abruptly around altitudes of 2000 km due to lateral transport. The diurnal variation of hot oxygen densities remains significant up to the altitude of 10000 km. The diurnal variation of the hot oxygen corona should thus be considered when the upcoming Nozomi measurements are analyzed. The non-spherical model of the hot oxy-gen corona may contribute to building sophisticate solar wind interaction models and thus result in more accurate escaping rate of oxygens from Mars.

대만산 배추 (Brassica campestris M.)로부터 분리한 BcHSPI7.6 cDNA(내열성 유전자)를 pBKSl-l vector에 subcloning하므로서, NPTII 유전자와 P35S-HSPI7.6 cDNA를 가지는 pBKH4 재조합 플라스미드를 제작하였다. 이들 플라스미드를 갖는 A. tumefaciens LBA4404로서 담배잎 단편을 24시간 동안 공배양하므로서 감염시켰으며, 이들 유전자로 형질전환된 shoot는 의 가나마이신을 첨

A small ultraviolet telescope which can be established on a satellite of the Korean small satellite (KITSAT) series is proposed with a concept design. Possible scientific objectives are identified, and the basic structure and characteristics of the telescope are described. In order to overcome limitation of pointing and stabilization accuracy of the KITSAT, a system of secondary stabilization is designed at the focal plane, where both star-tracking CCD and science detector share a 1.2deg field of view. Star tracking information is fed to three-axis drivers that move the platform on which the star-tracking CCD and science detector are installed. The proposed stabilization system is light and efficient, in comparison with a standard system of stabilization that basically moves the whole telescope or satellite. With a good intensified CCD and second stabilization system, the telescope will achieve a limiting magnitude of 21 at 1600 angstrom, which is sufficient for observing a variety of celestial objects, such as hot stars, nebulae, galaxies with UV excess, and quasars.

Observational trends of the Jovian UV aurora, obtained from the Goddard High Resolution Spectrograph(GHRS) on board the Hubble Space Telescope(HST), are explained by a simple two component model. The model consists of cool and warm components with temperatures of about 400 and 1000K, and with methane absorptions corresponding to column densities of 6-9e16/cm2 and no methane absorption, respectively. Three trends that (1) brighter UV spectra have lower temperatures, and (2) spectra with stronger methane absorption show lower temperatures, and (3) spectra with stronger methane absorption seem to be brighter, are accounted by combinations of two components with various filling factors and intensity ratios. The model implies that precipitating particles responsibie for the cool component have higher individual energy and stronger energy flux than those for the warm component. Estimation of GHRS aperture location on UV auroral images taken by the Wide Field Planetary Camera 2(WFPC2) suggests that the cool component may correspond to emission along the oval, and the warm component to diffuse features of UV emission. Preliminary comparison of images by the WFPC2 and those by H3+ 4 micrometer ground-based observations implies that the warm component causes both weak diffuse features of UV emission and bright H3+ emission in an area at lambda III - 150 deg. inside the northern oval.

We have analyzed infrared (IR) images of Jupiter which was observed at the McDonald Observatory, Texas, U.S.A., during the P/SHoemaker-LEvy 9 (SL9) impact period and about one week after the last impact. The IR images were obtained on the 2.7m telescope using a NICMOS array with filters to isolate the 1.5 μm NH3 band, the 2.3 μm CH4 band, the 2.12 μm H2 S(0) pressure-induced absorption, and the continua at 1.58 μm and 2.0 μm (short K-band). All images except those with the 1.58 μm continuum filter show bright impact sites against the relatively dark Jovian disk near the impact latitude of about 45° S. This implies that dusts originated from the impacts reflect the solar radiation at high altitudes before absorbed by stratospheric CH4, NH3 or H2. The impact sites observed with the 2.3 μm filter are conspicuously bright against a very dark background. The morphology of impact sites, G, L, and H at 2.3 and 2.12 μm filters shows clearly an asymmetric structure toward the incident direction of the comet fragments, in agreement with the studies of visible impact images obtained with the Hubble Space Telescope. Comparisons of reflectances of G, L, and H sites with simple radiative transfer models suggest that optically thick dust layers were formed at high altitudes at which methane absorption attenuates incoming sunlight only by about 1%. The dust layers in these sites seem to form at about the same altitude regardless of the magnitude of the impacts, but they appear to descend gradually after the impacts. The dust layers have optical depths of 2-5, according to the models.

Adult diapause in insects is characterized by suppression of reproductive development. It is induced by environmental cues such as photoperiod, temperature, food availability, and other conditions Diapause-inducing environment is recognized and analyzed by the brain of the insects. The interpreted information is conveyed via endocrine system to target tissues such as ovaries, fat body, and other tissues. From this signal hierarchy of a brain-endocrine-target tissue axis, several factors are involved to express a diapause trait in a quantitative mode, even though the insects show a binomial phenotye between being in diapause or not. Recent works estimated that the number of the factors is relatively small by a series of crossing trials between high and low diapause lines. Heritability of the diapause is quite high (ca. 70%) in some species. Epistasis, sex-linkage, pleiotropism, and other nongenetic components also affect diapause inheritance. Most physiological studies have been focused on control mechanisms of the juvenile hormone (JH) synthesis in corpora allata (CA) because JH level in hemolymph of teneral adults is critical to decide a later developmental mode. Allatostatin, an antagonizer of JH synthesis, has been believed to be a potent brain message to CA for adult diapause induction.

본 논문에서는 동특성추정법 (system identification) 을 이용한 교량구조의 손상정도를 평가하는 방법이 제 시되었다. 손상된 구조물의 비선형 동적거동은 휩모우멘트와 곡률반경의 시간이력 관계로써 표시하였으며， 구조물의 성질을 나타내는 특성계수는 실측자료를 이용한 동특성추정법을 사용하여 추정하였다. 또한， 구조 물의 성질의 다양성과 응답의 불확실성을 고려하여 손상은 확률변수로 나타내었으며， 예제해석으로는 곡선교 의 손상도추정이 수행되었다.