• Journal of Crop Science and Biotechnology
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• v.10 no.1
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• pp.45-49
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• 2007

Silicon is one of the key elements for healthy growth and development in rice crops. We analyzed the effect of silicon(Si) on some growth parameters, plant mineral contents, and bioactive gibberellins in three rice cultivars. Silicon was applied at the rates of 0 kg/0.1ha(control), 40 kg/0.1ha, and 80 kg/0.1ha throughout the course of experiment. Plant growth parameters were enhanced by the application of elevated Si, though plant height and culm length were more favorably affected than the respective dry weights. The plant mineral contents analyzed also increased in treatments where Si was applied without potassium, demonstrating that Si application promotes the absorption of these minerals in rice crops. The endogenous gibberellins measured in our study showed that $GA_1$ is the only bioactive GA form present in rice seedlings. The endogenous $GA_1$ and its precursor $GA_{20}$ contents increased after Si application. However, this increase in endogenous $GA_1$ and $GA_{20}$ contents, and plant growth parameters were different according to the rice cultivars. Our results indicate that Si is a beneficial element in rice nutrition and that different cultivars of Oryza sativa show differential responses to Si nutrition in terms of their growth and development.

• Geophysics and Geophysical Exploration
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• v.5 no.4
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• pp.291-298
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• 2002

We have developed a two-dimensional (2-D) magnetotelluric (MT) inversion algorithm, which can include topographic effects in inversion. We use the finite element method (FEM) to incorporate topography into forward calculation. Topography is implemented simply by moving nodes of rectangular elements in z-direction according to the elevation of air-earth interface. In the inversion process, we adopt a spatially variable Lagrangian multiplier algorithm in the smoothness-constrained least-squares inversion. The inversion algorithm developed in this study reconstructs subsurface resistivity structure quite well when topography variation exists. Also, it turns out to be effective in both resolution and stability from a model study and field data application.

• Analytical Science and Technology
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• v.17 no.4
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• pp.302-307
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• 2004

Determination of actinides in the environmental sample requires separation of each element. This procedure is tedious and time consuming. And also, the detection limits of some nuclides using alpha spectrometry are rather higher. To overcome the lower detection limit and complicated separation procedure, a simple analytical technique for the determination of actinide isotopes in the environmental samples was developed and applied to IAEA and NIST reference sediment samples. For the separation of actinides from matrix, anion exchange resin and TRU-spec extraction chromatography resin were used and chemical yields were obtained using natural uranium, thorium, $^{242}Pu$ and $^{243}Am$ tracers. For overcoming the higher detection limits of U and Th in alpha spectrometry, neutron activation analysis was applied. Using combined method, the detection limit was increased about 10 times. The activity values of each isotope were consistent with the reference values reported by IAEA and NIST.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.53-59
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• 2022

DEXA, as the standard areal bone mineral density (aBMD) measurement method, often shows an insuficient correlation between aBMDs of the measured bones and referring bones and is inaccurate due to the mass effect. In contrast, quantitative computer tomography (QCT), as a volumetric BMD (vBMD) measurement method, is being advanced so that it uses less radiation before, owing to improved CT device and computer imaging technology. Because dual-energy CTs can modulate the image signals showing tumor or specific chemicals as well as the ability to measure vBMD, they are expanding their application. For pre-checking vBMD of surgeon-specific bone volume at implantation candidate sites, a finite element creation-based local vBMD measurement technique was developed. The local vBMD measurement function for surgeon-specific shape volumes will be added to clinical imaging systems.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.252-260
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• 2008

This study was conducted to observe the characteristics of mineral nutrient uptake of single-node cutting rose 'Versilla' and to determine optimal nutrient solution control method for soilless culture of 'Versilla' in a closed hydroponic system. Nutrient solution was managed by five different control methods: macro- and micro-element control in aeroponic system (M&M), macroelement control in aeroponic system (M), nutrient solution supplement in aeroponic system (S); electrical conductivity (EC) control in aeroponic system(EC-A); EC control in deep flow technique system(EC-D). The concentration of $NO_3$-N exceeds optimal range whereas P and Mg decreased at the later stage of plant growth with the EC control method, EC-A and EC-D. The overall mineral nutrient content increased with S. On the other hand the nutrient content at the root environment was maintained optimal with M&M and M. The nutrient solution control methods had significantly effect on the cut-flower quality. In the M&M and M, flower length, fresh weight and root activity were higher than those with the other mineral nutrients control methods. The maximal efficiency of photochemistry (Fv/Fm) was higher for M&M, M and S than that with EC-A and EC-D. Based on the above results, it is highly recommended to control nutrient solution by mineral nutrient control methods (M&M and M) in a closed hydroponic system for single-node cutting rose, 'Versillia'.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.593-609
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• 2021

We proposed a numerical method for the thermo-mechanical behavior of rock fracture using a grain-based distinct element model (GBDEM) and simulated thermally induced fracture slip. The present study is the benchmark simulation performed as part of DECOVALEX-2023 Task G, which aims to develop a numerical method to estimate the coupled thermo-hydro-mechanical processes within the crystalline rock fracture network. We represented the rock sample as an assembly of Voronoi grains and calculated the interaction of the grains (blocks) and their interfaces (contacts) using a distinct element code, 3DEC. Based on an equivalent continuum approach, the micro-parameters of grains and contacts were determined to reproduce rock as an elastic material. Then, the behavior of the fracture embedded in the rock was characterized by the contacts with Coulomb shear strength and tensile strength. In the benchmark simulation, we quantitatively examined the effects of the boundary stress and thermal stress due to heat conduction on fracture behavior, focusing on the mechanism of thermally induced fracture slip. The simulation results showed that the developed numerical model reasonably reproduced the thermal expansion and thermal stress increment, the fracture stress and displacement and the effect of boundary condition. We expect the numerical model to be enhanced by continuing collaboration and interaction with other research teams of DECOVALEX-2023 Task G and validated in further study experiments.

• Economic and Environmental Geology
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• v.49 no.6
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• pp.417-432
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• 2016

It was firstly revealed in this research that the marine terrace of the Ijin-ri (Bukpyung-myeon, Haenam-gun) was formed during the last interglacial (Marine Isotope Stage 5e; MIS 5e). The marine terrace totally ranging from 4.8 m (asl) to 8.8 m (asl) is subdivided into 4 units; Unit I ranges 4.8-5.3 m, unit II ranges 5.3-6.9 m, unit III ranges 6.9-8.3 m, and unit IV ranges 8.3-8.8 m. Strong evidences that units II and III were formed during MIS5e were obtained based on OSL dating, the physical characterizations such as particle size distribution, magnetic susceptibility and water content, principal element and trace element analyses, and quantitative clay mineral analysis for samples at the 30 cm intervals. The rounded gravels on the marine terrace are regarded to be originated from the clastic materials transported directly from the surrounding mountains toward the marine and abraded in the coastal area, without any fluvial processes. During the warmest period (125k, unit II), the increase in rainfall, along with the rapid rise in sea level, was likely caused the high amount of clastic materials transported to the upper part of the beach. As a result of comparing clay mineral ratios of study site with those derived from sediments of either tidal flats, or the Yellow Sea, it is interpreted that the sediments of study site were influenced from the marine. The results will be used to investigate the hydrological activity and sedimentary environment during the high sea level in the past.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.629-630
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• 2012

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1993.10a
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• pp.9-10
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• 1993

최근의 배추 소비경향은 월동을 위한 다량의 김장을 담그는 것보다는 주년을 통해서 신선한 고품질의 배추의 요구가 매년 증가하고 있다. 따라서 종래 배추재배양식에서 벗어나 시설을 이용해 동기부터 춘기에 걸친 배추 재배면적이 매년 늘어나고 있는 것이 현실이다. 그러나 특히 배추의 시설재배에서는 동기부터 춘기에 걸쳐 칼슘결여에 기인되는 생리장애의 일종인 Tipburn이 발생해서 상품성이 떨어져 재배농가의 대단한 경제손실이 되고있다. (중략)

• 한국약용작물학회:학술대회논문집
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• 2010.10a
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• pp.258-259
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• 2010