• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1120-1131
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• 2003

A recently developed numerical method based on a mixed volume and boundary integral equation method is applied to calculate the accurate stress intensity factors at the crack tips in unbounded isotropic solids in the presence of multiple anisotropic inclusions and cracks subject to external loads. Firstly, it should be noted that this newly developed numerical method does not require the Green's function for anisotropic inclusions to solve this class of problems since only Green's function for the unbounded isotropic matrix is involved in their formulation for the analysis. Secondly, this method takes full advantage of the capabilities developed in FEM and BIEM. In this paper, a detailed analysis of the stress intensity factors are carried out for an unbounded isotropic matrix containing an orthotropic cylindrical inclusion and a crack. The accuracy and effectiveness of the new method are examined through comparison with results obtained from analytical method and volume integral equation method. It is demonstrated that this new method is very accurate and effective for solving plane elastostatic problems in unbounded solids containing anisotropic inclusions and cracks.

• Bulletin of the Korean Chemical Society
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• v.27 no.6
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• pp.863-868
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• 2006

The partial least squares (PLS-1) calibration model based on spectrophotometric measurement, for the simultaneous determination of sulfite and sulfide is described. This method is based on the difference between the rate of the reaction of sulfide and sulfite with Malachite Green in pH 7.0 buffer solution and at 25 ${^{\circ}C}$. The absorption kinetic profiles of the solutions were monitored by measuring the decrease in the absorbance of Malachite Green at 617 nm in the time range 10-180 s after initiation of the reactions with 2 s intervals. The experimental calibration matrix for partial least squares (PLS-1) calibration was designed with 24 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range 0.030-1.5 and 0.030-1.2 $\mu$g m$L ^{-1}$ for sulfite and sulfide, respectively. The proposed method was successfully applied to simultaneous determination of sulfite and sulfide in water samples and whole human blood.

• Economic and Environmental Geology
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• v.27 no.1
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• pp.41-47
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• 1994

A fast Hankel transform (FHT) algorithm (Anderson, 1982) is applied to numerical evaluation of many Green's tensor integrals encountered in three-dimensional electromagnetic modeling using integral equations. Efficient computation of Hankel transforms is obtained by a combination of related and lagged convolutions which are available in the FHT. We express Green's tensor integrals for a layered half-space, and rewrite those to a form of related functions so that the FHT can be applied in an efficient manner. By use of the FHT, a complete or full matrix of the related Hankel transform can be rapidly and accurately calculated for about the same computation time as would be required for a single direct convolution. Computing time for a five-layer half-space shows that the FHT is about 117 and 4 times faster than conventional direct and multiple lagged convolution methods, respectively.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.04a
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• pp.17-27
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• 1995

For the post-buckling and elasto-plastic analysis of shell structures, the total Lagrangian formulation is presented based upon the degenerated shell element. Geometrically correct formulation is developed by updating the direction of normal vectors in the iteration process and evaluating the total Green-Lagrange stain corresponding U total displacements. In the calculation of the stiffness matrix, the element formulation takes into account the effect of finite rotation increments by retaining second order rotation terms in the incremental displacement field. The selective or reduced integration scheme using the heterosis element is applied in order to overcome both shear locking phenomena and the zero energy mode. The load/displacement incremental scheme is adopted for geometric non-linear F .E. analysis. Based on such methodology, the computer program is developed and numerical examples to demonstrate the accuracy and the effectiveness of the proposed shell element are presented and compared with references's results.

• ALGAE
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• v.27 no.1
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• pp.55-62
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• 2012

A novel lectin specific to N-acetyl-D-galactosamine as well as N-acetyl-D-glucosamine was isolated from Bryopsis plumosa and named as BPL-4. Sodium dodecyl sulfate polyacrylamide gel electrophorese (SDS-PAGE) and matrix-assisted laser desorption / ionization-time of flight (MALDI-TOF) mass spectrometry data showed that this lectin was a monomeric protein with molecular weight 12.9 kDa. The N-terminal amino acid sequences of the lectin were determined by Edman degradation and the full cDNA sequence encoding this lectin was obtained using the degenerate primers designed from the amino acid sequence. The size of the cDNA was 414 bp containing single open reading frame (ORF) encoding the lectin precursor. The homology analysis showed that this lectin might belong to H lectin group. BPL-4 showed high sequence similarity (60.6%) to BPL-3, which is a previously reported lectin from the same species. The comparative analysis on the lectin's primary structure showed two conserved domains including one possible active domain of H lectin group.

• Economic and Environmental Geology
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• v.27 no.2
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• pp.191-199
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• 1994

We have developed an algorithm based on the method of integral equations to simulate the magnetotelluric (MT) responses of three-dimensional (3-D) bodies in a layered half-space. The inhomogeneities are divided into a number of cells and are replaced by an equivalent current distribution which is approximated by pulse basis functions. A matrix equation is constructed using the electric Green's tensor function appropriate to a layered earth, and is solved for the vector current in each cell. Subsequently, scattered fields are found by integrating electric and magnetic Green's tensor functions over the scattering current About a 3-D conductive body near the earth's surface, interpretation using 2-D transverse electric modeling schemes can imply highly erratic low resistivities at depth. This is why these routines do not account for the effect of boundary charges. However, centrally located profiles across elongate 3-D prisms may be modeled accurately with a 2-D transverse magnetic algorithm, which implicitly includes boundary charges in its formulation. Multifrequency calculations show that apparent resistivity and impedance phase are really two complementary parameters. Hence, they should be treated simultaneously in broadband MT interpretation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.348-357
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• 2015

The main purpose of this study is to understand the potential geographic distribution of P. koraiensis, which is known to be one of major economic tree species, based on the RCP (Representative Concentration Pathway) 8.5 scenarios and current geographic distribution from National Forest Inventory(NFI) data using ecological niche modeling. P. koraiensis abundance data extracted from NFI were utilized to estimate current geographic distribution. Also, GARP (Genetic Algorithm for Rule-set Production) model, one of the ecological niche models, was applied to estimate potential geographic distribution and to project future changes. Environmental explanatory variables showing Area Under Curve (AUC) value bigger than 0.6 were selected and constructed into the final model by running the model for each of the 27 variables. The results of the model validation which was performed based on confusion matrix statistics, showed quite high suitability. Currently P. koraiensis is distributed widely from 300m to 1,200m in altitude and from south to north as a result of national greening project in 1970s although major populations are found in elevated and northern area. The results of this study were successful in showing the current distribution of P. koraiensis and projecting their future changes. Future model for P. koraiensis suggest large areas predicted under current climate conditions may be contracted by 2090s showing dramatic habitat loss. Considering the increasing status of atmospheric $CO_2$ and air temperature in Korea, P. koraiensis seems to experience the significant decrease of potential distribution range in the future. The final model in this study may be used to identify climate change impacts on distribution of P. koraiensis in Korea, and a deeper understanding of its correlation may be helpful when planning afforestation strategies.

• The Korean Journal of Ecology
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• v.26 no.5
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• pp.237-246
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• 2003

A mountain village is defined as that which is autogenously formed over at least 100 years and supported by agricultural yields and forest products and forest area portion of which is over 70% in Guidelines for the Comprehensive Development Planning of Mountain Village. Recently, concerns about management planning of the Green and Eco-Village causes researches related to the Mountain Village's economics, tourism attractiveness, experience programming and investigation of the ecosystem and environment based on the village area. This kind of eco-village project should be supported by ecological evaluation of its spatial structure. But there is rare research of the village spatial structure studied from the ecological viewpoint originally. The purpose of this study is to interpret the spatial structure of Korean mountain village on the landscape ecological paradigm. The paradigm components are patches, corridors, networks, and matrix which explain the land and spatial structure at landscape scale. For this purpose, we selected two case study areas- Sansu and Ajick villages in Gimje city, Jeonlabukdo. We interpreted and evaluated the spatial structure by three steps: (1) to clarify the existing land mosaic pattern by land use mapping (2) to estimate the pore size as development area in matrix (3) to investigate the funnel effect of patch shape. These landscape ecological steps and frameworks could be applied for the proper methodology as fundamentals of eco-village planning and design.

• Fisheries and Aquatic Sciences
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• v.22 no.12
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• pp.31.1-31.12
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• 2019

Background: The black-chinned tilapia, Sarotherodon melanotheron, is the most abundant fish species in the Nakwa (an open lagoon) and Brenu (a closed lagoon) in the Central Region of Ghana. Aspects of the life history characteristics and the ecology of the fish populations in both lagoons were studied to assess the bio-ecological status of this important resource. Methods: Fish samples were obtained from fishermen that fish on the Nakwa and Brenu lagoons using cast, drag and gill nets. The age of the fish was assessed from otoliths analysis and its growth modelled following the von Bertalanffy growth function. Morphometric characteristics of the fish populations were analysed using power regression and ANOVA for parameters comparisons, and Student's t test to determine whether species grew isometrically. The percentage occurrence method was used to analyse the stomach contents of the fish. Results: A total of 382 fish samples from both lagoons were measured, comprising 209 from Nakwa lagoon and 176 from Brenu lagoon. The size and weight of fish samples ranged between 3.9-11.5 cm total length and 1.0-27.3 g for Nakwa Lagoon and 5.6-12.8 cm total length and 3.2-29.8 g for the Brenu Lagoon. The estimated von Bertalanffy growth parameters were L∞ = 12.04 cm and K = 2.76/year for the Nakwa Lagoon samples and L∞ = 13.44 cm and K = 3.27/year for Brenu Lagoon samples. Daily otolith incremental rate ranged from 0.01-0.03 mm per day to 0.01-0.02 mm per day for Nakwa and Brenu lagoons, respectively. Stomach content analysis of the fish samples revealed that the species are planktivorous and the range of food varied between the lagoons. Green algae were the most prevalent food item in the stomachs of the fish samples from Nakwa with the frequency of 69% whilst diatoms (80.5%) were most prevalent phytoplanktonic food item for the fish in Brenu lagoon. Conclusions: The estimates of asymptotic length for the species in both lagoons are close to known values of the species length at first sexual maturity and points to intensive fishing pressure. As a consequence, a comprehensive sample-based survey is required in both lagoons to derive estimates of management reference points. The results of the stomach content analysis are beneficial to the construction of diet matrix for ecosystem models of the two systems.

• Journal of Sericultural and Entomological Science
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• v.25 no.2
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• pp.1-31
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• 1984

Flacherie, as one of the most prevalent silkworm diseases, causes severe economic damage to sericultural industry and its pathogens have been proved to be flacherie virus (FV) and densonucleosis virus (DNV). Multiplications of the viruses in the larvae of the silkworm, Bombyx mori, were studied by the sucrose density gradient centrifugation and electron microscopy. The quantitative and qualitative changes of nucleic acids and proteins were investigated from the midgut and hemolymph in the silkworm larvae infected separately with FV and DNV. The histopathological changes of epithelial cells of infected midgut also were examined by an electron microscope. 1. Purified fractions of FV or DNV in a sucrose density gradient centrifugation yielded one homogenous and sharp peak without a shoulder, suggesting no heterogenous materials in the preparation. Electron microscopy also revealed that FV and DNV were spherical particles, 27nm and 21nm in diameter, respectively. 2. Silkworm larvae showed a decrease in body weight on the 6th day and in midgut weight on the 3rd day after inoculation with FV or DNV. 3. DNA content was higher in the midgut when infected with FV or DNV, but the hemolymph of the infected larvae showed no difference during first 6 days after inoculation, after which DNA concentration declined rapidly. 4. RNA synthesis of silkworm larvae infected separately with FV and DNV was stimulated in the midgut, but RNA content was reduced in the hemolymph at the early stage of virus multiplication. At the late stage of virus multiplication, however, it was extremely reduced in both midgut and hemolymph. 5. The concentration of protein in the midgut and hemolymph of silkworm larvae infected separately with FV and DNV showed no difference from that of the healthy larvae at the early stage of virus multiplication, but it was significantly reduced at the late stage of virus multiplication. 6. There was no difference in the electrophoretic patterns of RNAs extracted from the midgut of healthy or virus-infected larvae. 7. The electrophoresis of proteins extracted from the midgut infected with FV or DNV, when carried out on the 1st and 5th day after virus inoculation, showed no difference from that of the healthy larvae. But, there was an additional band with medium motility in the proteins on the 8th day after virus inoculation, while a band with low mobility shown in the proteins of healthy larvae disappeared in the infected larvae. However, a band with high mobility in the healthy larvae was separated into two fractions in the infected larvae. 8. The electrophoretic pattern of hemolymph proteins of the silkworm larvae infected separately with FV and DNV was similar to that of the healthy larvae, but the concentration of hemolymph proteins in the infected larvae was lower than that of the healthy larvae at the late stage. 9. Two types of inclusion bodies were shown by the double staining of pyronin-methyl green in the columnar cell of the midgut on the 8th day after FV inoculation. 10. Electron microscopy of the infected midgut revealed that the 'cytoplasmic wall' of the goblet cell thickened on the 5th day after FV inoculation and several types of the cytopathogenic structures, such as virus$.$specific vesicles, virus particles, linear structures, tubular structures, and high electron-dense matrices were observed in the cytoplasm of the goblet cell. The virus particles were also observed in the microvilli and the structures similar to spherical virus particles were observed around the virus-specific vesicles, suggesting the virus assembly in the cytoplasm. 11. Fluorescence micrograph of the infected midgut stained with acridine orange showed that the nucleus, the site of DNV multiplication in the columnar cell, enlarged on the 5th day after virus inoculation. 12. Electron microscopic examination of DNV infected midgut revealed that the nucleolus of the columnar cell was broken into granules and those granules dispersed into apical region of the nucleus on the 5th day after virus inoculation. On the 8th day after inoculation, it was also observed that the nucleus of the columnar cell was full with the high electron-dense virogenic stroma which were similar to virus particles. These facts suggest that the virogenic stroma were the sites of virus assembly in the process of DNV multiplication.