• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.50-56
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• 2020

With the rapid development of deep neural network theory and application research, the effect of face detection has been improved. However, due to the complexity of deep neural network calculation and the high complexity of the detection environment, how to detect face quickly and accurately becomes the main problem. This paper is based on the relatively simple model of the MTCNN model, using FDDB (Face Detection Dataset and Benchmark Homepage), LFW (Field Label Face) and FaceScrub public datasets as training samples. At the same time of sorting out and introducing MTCNN(Multi-Task Cascaded Convolutional Neural Network) model, it explores how to improve training speed and Increase performance at the same time. In this paper, the dynamic image pyramid technology is used to replace the traditional image pyramid technology to segment samples, and OHEM (the online hard example mine) function in MTCNN model is deleted in training, so as to improve the training speed.

• Advances in concrete construction
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• v.13 no.1
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• pp.83-99
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• 2022

The two, NBD and SCB tests using gypsum circular discs each containing a single notch have been experimentally accomplished in a rock mechanics laboratory. These specimens have also been numerically modelled by a two-dimensional particle flow which is based on Discrete Element Method (DEM). Each testing specimen had a thickness of 5 cm with 10 cm in diameter. The specimens' lengths varied as 2, 3, and 4 cm; and the specimens' notch angles varied as 0°, 45° and 90°. Similar semi-circular gypsum specimens were also prepared each contained one edge notch with angles 0° or 45°. The uniaxial testing machine was used to perform the experimental tests for both NBD and SCB gypsum specimens. At the same time, the numerical simulation of these tests were performed by PFC2D. The experimental results showed that the failure mechanism of rocks is mainly affected by the orientations of joints with respect to the loading directions. The failure mechanism and fracturing patterns of the gypsum specimens are directly related to the final failure loading. It has been shown that the number of induced tensile cracks showing the specimens' tensile behavior, and increases by decreasing the length and angle of joints. It should be noted that the fracture toughness of rocks' specimens obtained by NBD tests was higher than that of the SCB tests. The fracture toughness of rocks usually increases with the increasing of joints' angles but increasing the joints' lengths do not change the fracture toughness. The numerical solutions and the experimental results for both NDB and SCB tests give nearly similar fracture patterns during the loading process.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.569-580
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• 2013

Co-rich ferromanganese crusts (Fe-Mn crusts) distributed on the seamounts in the western Pacific are potential economic resources for cobalt, nickel, platinum, and other rare metals in the future. Regulations for prospecting and exploration of Fe-Mn crusts in the Area, which enables the process to obtain an exclusive exploration right for blocks of the fixed size, were enacted recently by the International Seabed Authority, which led to public attention on its potential for commercial development. Evaluation and selection of a mining site can be established based on abundance and grade of Fe-Mn crusts in the site as well as topography that should be smooth enough for mining efficiency. Therefore, acquisition of shipboard echo-sounding and acoustic backscatter data are prerequisite to select potential mine sites in addition to visual and sampling operations. Acoustic backscatter data can be used to locate crust-covered areas in a regional scale with the understanding of acoustic properties of crust through its correlation with visual and sampling data. KIOST had collected the topographic and geologic data to assess the resources potential for Fe-Mn crusts in the west Pacific region from 1994 to 2001. However, they could not obtain acoustic backscatter data that is crucial for the selection of prospective mining sites. Therefore, additional exploration surveys are required to carry out side scan sonar mapping combined with seafloor observation and sampling to decide the blocks for application of an exclusive exploration right.

• Geomechanics and Engineering
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• v.16 no.1
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• pp.35-47
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• 2018

This paper investigates the mechanisms of tunnel spalling and massive tunnel failures using fracture mechanics principles. The study starts with examining the fracture propagation due to tensile and shear failure mechanisms. It was found that, fundamentally, in rock masses with high compressive stresses, tensile fracture propagation is often a stable process which leads to a gradual failure. Shear fracture propagation tends to be an unstable process. Several real case observations of spalling failures and massive shear failures in boreholes, tunnels and underground roadways are shown in the paper. A number of numerical models were used to investigate the fracture mechanisms and extents in the roof/wall of a deep tunnel and in an underground coal mine roadway. The modelling was done using a unique fracture mechanics code FRACOD which simulates explicitly the fracture initiation and propagation process. The study has demonstrated that both tensile and shear fracturing may occur in the vicinity of an underground opening. Shallow spalling in the tunnel wall is believed to be caused by tensile fracturing from extensional strain although no tensile stress exists there. Massive large scale failure however is most likely to be caused by shear fracturing under high compressive stresses. The observation that tunnel spalling often starts when the hoop stress reaches $0.4^*UCS$ has been explained in this paper by using the extension strain criterion. At this uniaxial compressive stress level, the lateral extensional strain is equivalent to the critical strain under uniaxial tension. Scale effect on UCS commonly believed by many is unlikely the dominant factor in this phenomenon.

• Geomechanics and Engineering
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• v.20 no.5
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• pp.447-459
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• 2020

Based on the literature statistical method, the paper publication status of the isolated working face and the distribution of the rockburst coal mine were obtained. The numerical simulation method is used to study the stress distribution law of working face under different mining range. In addition, based on the similar material simulation test, the overlying strata failure modes and the deformation characteristics of coal pillars during the mining process of the isolated working face with thick-hard key strata are analyzed. The research shows that, under the influence of the key strata, the overlying strata formation above the isolated working face is a long arm T-type spatial structure. With the mining of the isolated working face, a series of damages occur in the coal pillars, causing the key strata to break and inducing the rockburst occurs. Combined with the mechanism of rockburst induced by the dynamic and static combined load, the source of dynamic and static load on the isolated working face is analyzed, and the rockburst monitoring methods and the prevention and control measures are proposed. Through the above research, the occurrence probability of rockburst can be effectively reduced, which is of great significance for the safe mining of deep coal mines.

• Resources Recycling
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• v.20 no.4
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• pp.3-22
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• 2011

Until recently, domestic high grade limestone have mainly mined so high grade limestone deposits have reduced. Because of exhaustion of high grade limestone, mine of limestone have moved from ground to deep position, the grade of limestone become lower because the amount of impurities and colored mineral increased as mining position become deeper. This paper was described about grade improvement of limestone to make a high grade limestone and suitable quality of limestone products by analysis of ore genesis and characteristics, supply and demand situation, use patterns and application standards of domestic lime-stone.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4275-4291
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• 2021

With the unprecedented growth of textual information on the Internet, an efficient automatic summarization system has become an urgent need. Recently, the neural network models based on the encoder-decoder with an attention mechanism have demonstrated powerful capabilities in the sentence summarization task. However, for paragraphs or longer document summarization, these models fail to mine the core information in the input text, which leads to information loss and repetitions. In this paper, we propose an abstractive document summarization method by applying guidance signals of key sentences to the encoder based on the hierarchical encoder-decoder architecture, denoted as KI-HABS. Specifically, we first train an extractor to extract key sentences in the input document by the hierarchical bidirectional GRU. Then, we encode the key sentences to the key information representation in the sentence level. Finally, we adopt key information representation guided selective encoding strategies to filter source information, which establishes a connection between the key sentences and the document. We use the CNN/Daily Mail and Gigaword datasets to evaluate our model. The experimental results demonstrate that our method generates more informative and concise summaries, achieving better performance than the competitive models.

• Journal of the Korean earth science society
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• v.22 no.4
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• pp.278-291
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• 2001

Mesothermal gold vein minerals of the Seolhwa mine were deposited in a single stage of massive quartz veins which filled the mainly NE-trending fault shear zones exclusively in the granitoid of the Gyeonggi Massif. The Seolhwa mesothermal gold mineralization is spatially associated with the Jurassic granitoid of 161 Ma. The vein quartz contains three main types of fluid inclusions at 25$^{\circ}$C: 1) low-salinity (< 5 wt.% NaCl), liquid CO$_{2}$-bearing, type IV inclusion; 2) gas-rich (> 70 vol.%), aqueous type II inclusions; 3) aqueous type I inclusions (0${\sim}$15 wt.% NaCl) containing small amounts of CO$_{2}$. The H$_{2}$O-CO$_{2}-CH$_{4}$-N$_{2}$-NaCl inclusions represent immiscible fluids trapped earlier along the solvurs curve at temperatures from 430$^{\circ}$ to 250$^{\circ}$C and pressures of 1 kbars. Detailed fluid inclusion chronologies may suggest a progressive decrease in pressure during the auriferous mineralization. The aqueous inclusion fluids represent either later fluids evelved through extensive fluid unmixing (CO$_{2}-CH$_{4}$ effervescence) from a homogeneous H$_{2}$O-CO$_{2}-CH$_{4}$-N$_{2}$-NaCl fluid due to decreases in temperature and pressure, or the influence of deep circulated meteoric waters possibly related to uplift and unloading of the mineralizing suites. The initial fluids were homogeneous containing H$_{2}$O-CO$_{2}-CH$_{4}$-N$_{2}$-NaCl components and the following properties: the initital temperature of >250$^{\circ}$ to 430$^{\circ}$C, X$_{CO}\;_{2}$ of 0.16 to 0.62, 5 to 14 mole% CH$_{4}$, 0.06 to 0.3 mole% N$_{2}$ and salinities of 0.4 to 4.9 wt.% NaCl. The T-X data for the Seolhwa gold mine may suggest that the Seolhwa auriferous hydrothermal system has been probably originated from adjacent granitic melt which facilitated the CH$_{4}$ formation and resulted in a reduced fluid state evidenced by the predominance of pyrrhotite. The dominance of negative ${\delta}\;^{34}$S values of sulfides (-0.6 to 1.4$%_o$o) are consistent with their deep igneous source.

• Journal of the Mineralogical Society of Korea
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• v.6 no.2
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• pp.94-104
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• 1993

The compositional variation of electrums from gold-silver and antimony deposits in the Dunjeon Baegjeon mining area, range from 22.6 to 69.5 atom% of Ag. Ag contents in electrums vary with paragenetic sequences and associated minerals. Ag contents increase from core to margin in a single grain. Compositional range of electrums from the North ore deposits of the Dunjeon gold mine are from 22.6 to 29.5 atom% of Ag. Electrums contain Cu(0.40 to 0.55 atom%) and Bi(0.35 to 0.67 atom%). Composition of electrums from the South ore deposits of the Dunjeon gold mine vasies from 33.6 to 69.5 atom% of Ag. Cu and As contents in electrums range from 0.20 to 1.92 and from 0.70 to 1.90 atom%, respectively. As the content of Ag in electrums increase, the contents of Bi and As in electrums increase but that of Cu decrease. Electrums of the Baegjeon gold deposits contain 35.6 to 63.5 atom% of Ag, suggesting that Au contents in electrums associated with base metal sulfied be higher than those associate with Ag-minerals. Ag/Au rations in electrums increase with decreasing temperature, salinity and $fs_2$ of the mineralizing solution.

• Economic and Environmental Geology
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• v.26 no.3
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• pp.259-265
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• 1993

The variation of H/F coefficient (Hubnerite/Feberite coefficient) and the temperature of formation with depth have been studied for the hydrothermal tungsten-quartz veins from Ssangjeon, Weolag, Cheongyang, and Sannae mines. All samples were selected at the same paragenetic stage and mineral assemblege according to depth. The studied mines provide an opportunity to examine and regional variations in wolframite composition in different provinces. The formation temperature is linearly related to the depth. At the Weolag, Cheongyang and Sannae mines, the H/F ratio of wolframite and filling temperatures of fluid inclusions in quartz show a general tendency to decrease at shallow levels, in spite of different geological settings. This implies the pH of fluid will decrease vertically with falling temperature and the high H/F ratio of wolframite in deep zone result in an increase of pH with depth. The Ssangjeon mine exhibits a tendency to increase slightly upwards at shallow level. This implies a different geochemical environment (high pH environment) for the Ssangjeon mine, as compared to the other three mines. The H/F coefficient pattern suggests that it is a useful geothermometer for vein-type tungsten deposits in Korea. The H/F coefficient as an indication of depth should be examined for use in exploration.