Pattern and origin of spherulites in a rhyolite dike swarm,northeastern Cheongsong, Korea

IntroductionThe northeastern Cheongsong area is underlainby a sequence of sedi mentary rocks together within-trusive and extrusive volcanic rocks all of late Creta-ceous age(Lee&Hong,1973;Ki m&Park,1970;Hwang,1998).Theintrusions,comprising astock,a plug and numerous dikes,are well exposedat the current surface due tothe enormous erosion ofany sedi mentary or volcanic covered rocks.Thedikes forma dike swarmand some are intruded intothe plug.The dikes swarm may represent the subsurfaceexpress…     

Advances in land modeling of KIAPS based on the Noah Land Surface Model

As of 2013, the Noah Land Surface Model (LSM) version 2.7.1 was implemented in a new global model being developed at the Korea Institute of Atmospheric Prediction Systems (KIAPS). This land surface scheme is further refined in two aspects, by adding new physical processes and by updating surface input parameters. Thus, the treatment of glacier land, sea ice, and snow cover are addressed more realistically. Inconsistencies in the amount of absorbed solar flux at ground level by the land surface and radiative processes are rectified. In addition, new parameters are available by using 1-km land cover data, which had usually not been possible at a global scale. Land surface albedo/emissivity climatology is newly created using Moderate-Resolution Imaging Spectroradiometer (MODIS) satellitebased data and adjusted parameterization. These updates have been applied to the KIAPS-developed model and generally provide a positive impact on near-surface weather forecasting.     

Comparison of microbial communities in petroleum-contaminated groundwater using genetic and metabolic profiles at Kyonggi-Do,South Korea

This research has been performed to determine the differences in microbial communities according to physicochemical properties such as concentrations of volatile aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene (BTEX), dissolved oxygen (DO), electron acceptors, etc., in oil-contaminated groundwaters at Kyonggi-Do, South Korea. The properties of bacterial and microbial communities were analyzed by 16S polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) fingerprinting method and community-level physiological profiling (CLPP) using Eco-plate, respectively. Based on the DGGE fingerprints, the similarities of bacterial community structures were high with similar DO levels, and low with different DO levels. Whereas the dominant bacterial groups in GW13 (highest BTEX and lowest DO) were acidobacteria, α-proteobacteria, β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and spirochetes, those in GW7 (highest BTEX and highest DO) were actinobacteria, α-proteobacteria, β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and sphingobacteria. Based on the CLPP results, the groundwater samples were roughly divided into three groups: above 4 mg/L in DO (group 1: GW3 and GW7), below 4 mg/L in DO (group 2: GW8, W1, W2, W3, and BH10), and highly contaminated with BTEX (group 3: GW13). Shannon index showed that the microbial diversities and equitabilities were higher in shallower aquifer samples. Overall, this study verified that the greatest influencing factors on microbial/bacterial communities in groundwaters were DO and carbon sources, although BTEX concentration was one of the major factors.     

Decadal change in relationship between western North Pacific tropical cyclone frequency and the tropical Pacific SST

In this study, we examine the relationship between the number of tropical cyclones (TCs) in the western North Pacific and the tropical Pacific sea surface temperature (SST) during the main TC season (July–November) for the period of 1965–2006. Results show that there are periods when TC frequency and the tropical Pacific SST are well correlated and periods when the relationship breaks down. Therefore, decadal variation is readily apparent in the relationship between the TC frequency and the SST variations in the tropical Pacific. We further examine the oceanic and atmospheric states in the two periods (i.e., 1979–1989 vs. 1990–2000) when the marked contrast in the correlation between the TC frequency and the tropical Pacific SST is observed. Before 1990, the analysis indicates that oceanic conditions largely influenced anomalous TC frequency, whereas atmospheric conditions had little impact. After 1990, there the reverse appears to be the case, i.e., atmospheric conditions drive anomalous TC frequency and oceanic conditions are relatively unimportant. A role of atmosphere and ocean in relation to the TC development in the western North Pacific changes, which is consistent with the change of the correlations between the TC frequency and the tropical Pacific SST.     

Restoration of an inner-city stream and its impact on air temperature and humidity based on long-term monitoring data

Spatiotemporal changes in air temperature and humidity associated with the restoration of an inner-city stream in Seoul, Korea, are investigated based on long-term monitoring data. The Cheonggye stream, covered under a concrete structure for 46 years, was restored in 2005 and runs 5.8 km eastward through a central region of Seoul. Long-term monitoring of the air temperature and relative humidity was made along the stream throughout the restoration and across the stream after the restoration. The area along the stream had a higher air temperature than the entire metropolitan area. The temperature anomaly between the monitoring area and the surrounding metropolitan area was 0.13^oC lower on average at the center of the stream after the restoration. The stream's effect on the air temperature was also evident in the temperature distribution along a street traversing the stream. The relative and specific humidities were increased due to the restoration. The restored stream modified the nearby urban climate in the opposite direction compared to urbanization. The results could be used as a model case in mitigating urban climate by a stream in future urban planning practices.     

Effect of magnetic field on a shock-induced thermal instability

The effect of a magnetic field on a thermal instability has been studied in a radiatively cooling region behind an interstellar shock of moderate propagation velocity ( 10 km s^–1). It is shown that the presence of a magnetic field of a few microgauss is very effective in preventing the thermal instability from building-up density concentrations. In the absence of the magnetic field, the shock-induced thermal instability will amplify a pre-shock density inhomogeneity by more than an order of magnitude. However, in the field's presence, the amplified density contrast is shown to be only a factor 2. Implications for the trace of a sweeping broom in the Pleiades nebula are discussed.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

Soil–pile–structure interaction under SH wave excitation

A continuum model for the interaction analysis of a fully coupled soil–pile–structure system under seismic excitation is presented in this paper. Only horizontal shaking induced by harmonic SH waves is considered so that the soil–pile–structure system is under anti‐plane deformation. The soil mass, pile and superstructure were all considered as elastic with hysteretic damping, while geometrically both pile and structures were simplified as a beam model. Buildings of various heights in Hong Kong designed to resist wind load were analysed using the present model. It was discovered that the acceleration of the piled‐structures at ground level can, in general, be larger than that of a free‐field shaking of the soil site, depending on the excitation frequency. For typical piled‐structures in Hong Kong, the amplification factor of shaking at the ground level does not show simple trends with the number of storeys of the superstructure, the thickness and the stiffness of soil, and the stiffness of the superstructure if number of storeys is fixed. The effect of pile stiffness on the amplification factor of shaking is, however, insignificant. Thus, simply increasing the pile size or the superstructure stiffness does not necessarily improve the seismic resistance of the soil–pile–structure system; on the contrary, it may lead to excessive amplification of shaking for the whole system. Copyright © 2003 John Wiley & Sons, Ltd.     

Environmental impact and geochemistry of old tailing pile from the Sanggok mine creek, Republic of Korea

This study evaluates the pollution load on a creek based on the physicochemical and mineralogical properties of old tailings. The Sanggok mine is one of the largest lead–zinc producers in the Hwanggangri mining district, Republic of Korea. The vertical profile of the old tailings in the mine area can be divided into three units based on color change, and mineralogical and textural variations, as well as physical and chemical properties. Unit I (surface accumulation and oxidized heterogeneous tailing soil) has lower pH and higher Eh than unit II (originally unoxidized dumped tailing soil) and unit III (pebble-bearing bottom soil). The conductivity data indicates that unit I and II have very high values compared to unit III and basement. The mine area consists mainly of carbonate rocks; however, mineral constituents of tailing soil and sediments near the mine were mainly composed of quartz, mica, feldspar, amphibole, calcite, dolomite, magnesite, and clay minerals. Units I and II are characterized by high abundances of siderite, locally pyrite, and dolomite. Precipitates in the mining drainage mainly included: smectite, illite, berthierine, quartz, siderite, hexahydrite, and Ca-ferrate. Among the separated metallic minerals, tailing soils and sediments of highly concentrated toxic metals are found: some pyrite, arsenopyrite, chalcopyrite, sphalerite, galena, malachite, goethite, various hydroxide, and uncertain secondary minerals. Units I and II are characterized by relatively high concentrations of Ca, Fe, Mn and low contents of Al, Mg, K, Na, Ti, rare earth elements (REEs) that correlated with the proportion of secondary minerals. Potentially toxic elements such as Ag, As, Cd, Cu, Pb, Sb, and Zn are highly enriched in the upper two units. This metal concentration can be influenced by changes in the depth because of oxic and suboxic zonal distribution. The removal zone (unit I) has probably migrated below the elevation of the maximum enrichment layer due to deepening of the oxic/suboxic boundary. In most of the materials, the enrichment index is higher than 3.62. The highest value of 42.55 is found in the oxidation surface soils of the tailing pile. An average enrichment index of the profiles and precipitates are 27.62 and 22.62, respectively. Rocky basement soils have an average enrichment index of 6.63, which is influenced by overlying the tailing pile. The water quality and habitat of the Sanggok creek are severely polluted. Polluted surface water may also negatively impact the agricultural soil and groundwater.     

Multisite campaign on the open cluster M67 – II. Evidence for solar-like oscillations in red giant stars

Measuring solar-like oscillations in an ensemble of stars in a cluster, holds promise for testing stellar structure and evolution more stringently than just fitting parameters to single field stars. The most-ambitious attempt to pursue these prospects was by Gilliland et al. who targeted 11 turn-off stars in the open cluster M67 (NGC 2682), but the oscillation amplitudes were too small (<20 μmag) to obtain unambiguous detections. Like Gilliland et al. we also aim at detecting solar-like oscillations in M67, but we target red giant stars with expected amplitudes in the range 50–  500 μmag  and periods of 1 to 8 h. We analyse our recently published photometry measurements, obtained during a six-week multisite campaign using nine telescopes around the world. The observations are compared with simulations and with estimated properties of the stellar oscillations. Noise levels in the Fourier spectra as low as  27 μmag  are obtained for single sites, while the combined data reach  19 μmag  , making this the best photometric time series of an ensemble of red giant stars. These data enable us to make the first test of the scaling relations (used to estimate frequency and amplitude) with an homogeneous ensemble of stars. The detected excess power is consistent with the expected signal from stellar oscillations, both in terms of its frequency range and amplitude. However, our results are limited by apparent high levels of non-white noise, which cannot be clearly separated from the stellar signal.     

Genesis and Mineralogy of Serpentinite Deposits,West of South Korea

The serpentinite deposits derived from ultramafic rockswithin the South Korea mainly occur in the west ofChungcheongnam - Do,the south of South Korea,Ulsan andAndong area,and in the middle of South Korea,Gapyeongarea. The present study is on the genesis and m ineral compo-sitions of the serpentinite deposits consisting of abouteighteenmasses in the west of Chungcheongnam- Do. The ultramaficrocks mainly occur as discontinuously isolated lenticular or el-liptical bodies and extend to NNE d…