• Transactions on Electrical and Electronic Materials
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• v.9 no.5
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• pp.186-192
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• 2008

Cross linked polyethylene (XLPE) insulators are used as insulation in ultra-high voltage electric power cables. This study investigated the electrical properties of XLPE at different temperatures. The electrical properties of the changing tree phenomenon was examined as a function of temperature applied to the electrical conductors by measuring the partial discharge at $25^{\circ}C$ to $80^{\circ}C$ and applied voltages to the electrodes ranging from 1 kV to 40 kV. The activity of the partial discharge was examined at various temperatures using the K-means distribution. The results revealed the specimen at $80^{\circ}C$ to have the lowest inception voltage and breakdown voltage. In addition, the core of clusters was moved $0^{\circ}$ and $180^{\circ}$ at the positive region and $180^{\circ}$ and $360^{\circ}$ in the negative region in the K-means. The distribution of clusters was concentrated on the inception condition and spread out widely at the breakdown voltage.

• Journal of Marine Life Science
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• v.7 no.1
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• pp.52-54
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• 2022

Mitochondrial genomes of three specimens of Gadus chalcogrammus Pallas 1,814 from Korea and Japan were completely analyzed by the primer walking method. They were 16,570~16,571 bp in length, each comprising 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes. Their gene orders were identical to those of conspecific specimens, but exhibited unique haplotypes. In the phylogenetic tree, the juvenile Korean and adult Japanese specimens were separated from the dominant clade composed of specimens from Japan, Korea, the Bering Sea, and the Arctic, including the adult Korean specimen.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.79-92
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• 2022

In this paper, the impact of a vernacular pozzolanic kaolinite mine on concrete alkali-silica reaction and strength has been evaluated. For making the samples, kaolinite powder with various levels has been used in the quality specification test of aggregates based on the ASTM C1260 standard in order to investigate the effect of kaolinite particles on reducing the reaction of the mortar bars. The compressive strength, X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) experiments have been performed on concrete specimens. The obtained results show that addition of kaolinite powder to concrete will cause a pozzolanic reaction and decrease the permeability of concrete samples comparing to the reference concrete specimen. Further, various machine learning methods have been used to predict ASR-induced expansion per different amounts of kaolinite. In the process of modeling methods, optimal method is considered to have the lowest mean square error (MSE) simultaneous to having the highest correlation coefficient (R). Therefore, to evaluate the efficiency of the proposed model, the results of the support vector machine (SVM) method were compared with the decision tree method, regression analysis and neural network algorithm. The results of comparison of forecasting tools showed that support vector machines have outperformed the results of other methods. Therefore, the support vector machine method can be mentioned as an effective approach to predict ASR-induced expansion.

• Journal of Korean Society of Forest Science
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• v.56 no.1
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• pp.66-76
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• 1982

Soil harness represents such physical properties as porosity, amount of water, bulk density and soil texture. It is very important to know the mechanical properties of soil as well as the chemical in order to research the fundamental phenomena in the growth and the distribution of tree roots. The writer intended to grip soil hardness by soil layer and also to grasp the root distribution and the correlation between soil hardness and the root distribution of Pinus riguda Mill. planted on the denuded hillside with sooding works by soil layer on soil profile. The site investigated is situated at Peongchang-ri 13, Kocksung county, Chon-nam Province. The area is consisted of 3.63 ha having on elevation of 167.5-207.5 m. Soil texture is sandy loam and parant rock in granite. Average slope of the area is $17^{\circ}-30^{\circ}$. Soil moisture condition is dry. Main exposure of the area is NW or SW. The total number of plots investigated was 24 plots. It divided into two groups by direction each 12 plots in NW and SW and divided into three groups by the position of mountain plots in foot of mountain, in hillside, and in summit of mountain, respectively. Each sampling tree was selected as specimen by purposive sampling and soil profile was made at the downward distance of 50cm form the sampling tree at each plot. Soil hardness, soil layer surveying, root distribution of the tree and vegetation were measured and investigated at the each plot. The soil hardness measured by the Yamanaka Soil Hardness Tester in mm unit. the results are as follows: 1) Soil hardness increases gradually in conformity with the increment of soil depth. The average soil indicator hardness by soil layer are as follows: 14.6mm in I - soil layer (0-10cm in depth from soil surface), 16.2mm in II - soil layer (10-20cm), 17.2 in III - soil layer (20-30cm), 18.3mm in IV - soil layer(30-40cm), 19.8mm in V - soil layer (4.50mm). 2) The tree roots (less than 20mm in diameter) distribute more in the surface layer than in the subsoil layer and decrease gradually according to the increment of soil depth. The ratio of the root distribution can be illustrated by comparing with each of five soil layers from surface to subsoil layer as follows: I - soil layer; 31%, II - soil layer; 26%, III - soil layer; 18%, IV - soil layer; 12%, V - soil layer; 13%, 3) Soil hardness and tree root distribution (less than 20mm in diameter) of Pinus rigida Mill. correlate negatively each other; the more soil hardness increases, the most root distribution decreases. The correlation coefficients between soil hardness and distribution of tree roots by soil layer are as follows: I - soil layer; -0.3675 (at the 10% significance level), II - soil layer; -0.5299 (at the 1% significance level), III - soil layer; -0.5573 (at the 2% significance level), IV - soil layer; -0.6922 (at the 5% significance level), V - soil layer; -0.7325 (at the 2% significance level). 4) the most suitable range of soil hardness for the growth of Pinus rigida Mill is the range of 12-14.9mm in soil indicator hardness. In this range of soil indicator hardness, the root distribution of this tree amounts to 41.8% in spite of 33% in soil harness and under the 20.9mm of soil indicator hardness, the distribution amounts to 93.2% in spite of 82% in soil hardness. Judging from above facts, the roots of Pinus rigida can easily grow within the soil condition of 20.9mm in soil indicator hardness. 5) The soil layers are classified by their depths from the surface soil.

• Journal of the Korean Society of Safety
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• v.38 no.4
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• pp.39-46
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• 2023

Pine trees, which account for 23% of the forested area of the Republic of Korea, are highly vulnerable to fire in comparison to broad-leaved trees due to the presence of consistent water tube sections throughout the year and resin that is composed of approximately 20% oil. In addition, the pattern of forest fires is determined by weather, topographic conditions, and fluctuation in moisture content. Therefore, when fire breaks out in pine tree forests during the dry season (January to March), it is difficult to extinguish, and it quickly spreads. In this study, the combustion characteristics of pine needles, pine cones, and pine branches in the water tube sections of living pine trees were compared and analyzed in accordance with the moisture content as per the ISO 5660-1. The monthly moisture content was analyzed from January to March, and it was found to be the lowest in March, with 53.6% for pine needles, 51.9% for pine branches, and 10.9% for pine cones. In particular, pine cones were more vulnerable to fire as compared to pine needles and pine branches because their moisture content was more than five times lower than that of pine needles and branches. The ignition time, which affects the speed of flame propagation, was the most rapid in March, and the fastest ignition time was for pine cones, at 19 seconds, followed by 34 seconds for pine needles, and 256 seconds for pine branches. The pine branches were the last to be ignited due to the effect of density, according to the thickness and specific gravity of the specimen. The peak heat release rate, which is a measurable index of fire intensity, was analyzed for pine cones and found to be 184.28 kW/m² , while the mean effective heat of combustion was 19.79 MJ/kg, and the total heat release rate was 39.7 MJ/m² , and these values were higher than those of pine branches and pine needles. Thus, we determined that the flame propagation speed and fire intensity according to the moisture content can be used to evaluate the risk of fire to the water tube section of pine trees. It is suggested that because of the combustion characteristics of the pine cone in March, that is when the forest is most vulnerable to fires.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.6
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• pp.390-395
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• 2015

Molded insulation materials are widely used from large electric power transformer apparatus to small electrical machinery and apparatus. In this study, by adding MgO with the average particle of several tens nm and the excellent thermal conductivity into molding material, we improved the problem of insulation breakdown strength decrease according to rising temperature in overload or in bad environmental condition. We confirmed the life evaluation by using the insulation breakdown and inverse involution to investigate the electrical characteristics of nano-composites materials. By using a scanning electron microscope, it is confirmed that MgO power with the average particle size of several tens nm is distributed and the filler particles is uniformly distributed in the cross section of specimens. And it is confirmed that the insulation breakdown strength of Virgin specimens is rapidly decreased at the high temperature area. But it is confirmed that the insulation breakdown strength of specimens added MgO slow decreased by thermal properties in the high temperature area improved by the contribution of the heat radiation of MgO and the suppression of tree. The results of life prediction using inverse involution, it is confirmed that the life of nano-composites is improved by contribution of MgO according to the predicted insulation breakdown strength after 10 years of specimens added 5.0 wt% of MgO is increased about 2.9 times at RT, and 4.9 times at $100^{\circ}C$ than Virgin specimen, respectively.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5613-5617
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• 2012

Gallbladder carcinoma (GBC) is the commonest cancer of the biliary tree and the most frequent cause of death from biliary malignancies. The incidence of GBC shows prominent geographic, age, race, and gender-related differences and is 4-7 times higher in patients with gallstones. This prompted us to study the clinicopathological aspects of the disease and the incidence of gallstones in gallbladder carcinoma patients, in this part of India. In this, combined retrospective (Jan 2004-March 2010) and prospective study (April 2010-Dec 2011) of eight years, 198 patients of gallbladder carcinoma (50 males and 148 females), (range 28-82 years; mean 55 years) were studied. Most of the patients were poor and presented with abdominal pain and mass, with abnormal lab parameters. Gallstones were present in 86% of patients. Surgical exploration was performed in 130, with gallbladder resection in 60 (including 7 incidental GBC). Adenocarcinoma (87.7%) was the commonest histological type. The study indicates that GBC is common in our scenario. It is a disease of elderly females, has a strong association with gallstones and every cholecystectomy specimen should be examined histopathologically.

• Mycobiology
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• v.42 no.3
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• pp.229-240
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• 2014

On the basis of extensive field investigation and a series of herbarium specimen identifications, we present and discuss the descriptions and distribution of 22 species of Ramalina found in the Hengduan Mountains of southwestern China. In this revisionary study, representatives of the Ramalina genus, including R. americana, R. confirmata, R. dendriscoides, R. obtusata, R. pacifica, R. pentecostii, R. peruviana, R. shinanoana, and R. subcomplanata are found for the first time in this area. In addition, R. holstii is reported for the first time China. Finally, a newly described species identified as Ramalina hengduanshanensis S. O. Oh & L. S. Wang is reported. It is characterized as growing from a narrow holdfast, solid, sparsely or richly and irregularly dichotomously branched, palmate and flattened lobes with distinctly dorsiventral appearance, surface rugose to reticulate, surface rugosely cracked, dense chondroid tissue, helmet shaped soralia at the tip. The species grows on rock and tree at the highest elevations in this area. Although very few lichen species belonging to the genus Ramalina have been collected above 4,000 m, this new species is found at this elevation. We present detailed morphological, anatomical, and chemical descriptions of this species along with molecular phylogenetic analysis of the internal transcribed spacer rDNA sequences.

• Tuberculosis and Respiratory Diseases
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• v.74 no.5
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• pp.231-234
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• 2013

Aspergillus causes a variety of clinical syndromes in the lung including tracheobronchial aspergillosis, invasive aspergillosis, chronic necrotizing pulmonary aspergillosis, allergic bronchopulmonary aspergillosis, and aspergilloma. Aspergilloma usually results from ingrowths of colonized Aspergillus in damaged bronchial tree, pulmonary cyst or cavities of patients with underlying lung diseases. There are a few reports on endobronchial aspergilloma without underlying pulmonary lesion. We have experienced a case of endobronchial aspergilloma associated with foreign body developed in an immunocompetent patient without underlying lung diseases. A 59-year-old man is being hospitalized with recurring hemoptysis for 5 months. X-ray and computed tomography scans of chest showed a nodular opacity in superior segment of left lower lobe. Fiberoptic bronchoscopy revealed an irregular, mass-like, brownish material which totally obstructed the sub-segmental bronchus and a foreign body in superior segmental bronchus of the lower left lobe. Histopathologic examinations of biopsy specimen revealed fungal hyphae, characteristic of Aspergillus species.

• Journal of Korean Society of Forest Science
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• v.94 no.4 s.161
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• pp.281-286
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• 2005

Trees enhance slope stability against down slope mass movement through the removal of soil water by transpiration and by the mechanical reinforcement of their roots. To assess the magnitude of this reinforcement on natural slope stability, direct shear tests were made on dry sand reinforced with different array types of roots. Pinus koraiensis was used as root specimens. The peak shear resistance at each normal stress level was measured on the rooted and unrooted soil specimens. Increased soil resistance(${\Delta}S$) by roots was calculated using parameters like internal friction angle and cohesion of tested soil and also evaluated the effects of root array in tested soil. As results, we find that shear resistance increased in tested soil shear box as diameters and arrayed numbers of root specimen increased and cross root array in tested soil had a much greater reinforcing effect than other root arrays. Comparison of traditional root-soil model with experiments showed that simulated reinforce strength by the model was different with those obtained by the experiment due to its linearity.