• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.199-210
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• 2003

The development of strain localization within shear zones is frequently observed during soil deformation. In fact, the phenomenon appears to be more often the norm rather than the exception. Conceptually, any soil condition that renders negative work increment is prone to localization. In this study, a broad range of soil and loading conditions are investigated to test this criterion, including: dilative soil subjected to drained shear (standard case), contractive soil sheared under undrained conditions, cavitation in dilative soil in undrained shear, inhomogeneous soils, particle alignment in contractive soils made of platy particles, soils that experience particle crushing, and the shear of low-moisture and/or lightly cemented loose soils. Unique specimens and test procedures are designed to separately test each of these soil conditions in the laboratory According to experimental test results, soil specimens with post-peak strain softening behavior are prone to progressive failure, localization of deformations, and shear banding. The state of stress, the soil density, inherent mechanical and geometrical properties of soil particles, low water content, and heterogeneity can contribute to triggering strain localization. Considering all possible cases of localization, the best method to obtain the critical state line in the laboratory is to use contractive homogeneous specimens subjected to drained shear.

• Transactions of Materials Processing
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• v.13 no.5
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• pp.422-428
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• 2004

At present, the design of extrusion dies and operation in extrusion companies are primarily based on trial and error. The experience of the die designer, the press operator and the die corrector determine the performance of the extrusion die and the efficiency of the process. In order to produce defect-free products of desirable quality in terms of strength, surface quality and geometrical dimensions, it is important to obtain more knowledge of the processes that occur during extrusion. Recently, to reduce the costs of designing and manufacturing of extrusion dies, and to ensure the quality of the extruded products, numerical simulation for extrusion processes such as FEM (finite element method) is applied increasingly and becomes a very important tool for the design and development of new products. However, most of the studies about FE simulation have been accomplished for simple geometry and low extrusion ratio in the filed of steady metal flow conditions. The extruded products of AI alloy in industrial practice involve complicated sectional geometry. This study was designed to reduce the time of die design and manufacturing in the extrusion process using FEM simulation. FEM simulations of extrusion process were performed in non-steady states conditions by changing weld plate included in extrusion die set. Product which was employed in this study is heat sink that has been used in the parts of heat exchanger of electric circuits. It is generally applied for aluminum or its alloys due to heat efficiency and easy production of complicated shapes, and manufactured by extrusion process. The simulated results showed that weld plate shape in extrusion dies influences meta] flow and dimensional accuracy of products.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.77-87
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• 1994

This paper deals with an automated forming sequence design system by which designers can determine desirable operation sequences even if they have little experience in the design of cold forging process. The forming sequence design in the cold forging is very important and requires many kinds of technical and empirical knowledge. They system isproposed, which generates forming sequence plans for the multistage cold forging of axisymmtrical solid products. Since the process of metal forming can be considered as a transformation of geometry, treatment of the geometry of the product is a key in planning process. To recognize the geometry of the product section, section entity representation and primitive geometries were used. Section entity representation can be used for the calculation of maximum diameter, maximum height, and volume. Forming sequence for the part can be determined by means of primitive geometries such as cylinder, cone, convex, and concave. By utilizing this geometrical characteristics (diameter, height, and radius), the product geometry is expressed by a list of the priitive geometries. Accordingly the forming sequence design is formulated as the search problem which starts with a billet geometry and finishes with a given product one. Using the developed system, the sequence drawing with all dimensions, which includes the proper sequence of operations for the part, is generated under the environment of AutoCAD. Based on the results of forming sequence, process variables(strain, punch pressure, die inner pressure, and forming load) are determined.

• Advances in nano research
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• v.16 no.3
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• pp.231-249
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• 2024

When the amplitude of the vibrations is equivalent to that clearance, the vibrations for small amplitudes will really be significantly nonlinear. Nonlinearities will not be significant for amplitudes that are rather modest. Finally, nonlinearities will become crucial once again for big amplitudes. Therefore, the concrete panel system may experience a big amplitude in this work as a result of the high temperature. Based on the 3D modeling of the shell theory, the current work shows the influences of the von Kármán strain-displacement kinematic nonlinearity on the constitutive laws of the structure. The system's governing Equations in the nonlinear form are solved using Kronecker and Hadamard products, the discretization of Equations on the space domain, and Duffing-type Equations. Thermo-elasticity Equations. are used to represent the system's temperature. The harmonic solution technique for the displacement domain and the multiple-scale approach for the time domain are both covered in the section on solution procedures for solving nonlinear Equations. An effective data-driven solution is often utilized to predict how different systems would behave. The number of hidden layers and the learning rate are two hyperparameters for the network that are often chosen manually when required. Additionally, the data-driven method is offered for addressing the nonlinear vibration issue in order to reduce the computing cost of the current study. The conclusions of the present study may be validated by contrasting them with those of data-driven solutions and other published articles. The findings show that certain physical and geometrical characteristics have a significant effect on the existing concrete panel structure's susceptibility to temperature change and GPL weight fraction. For building construction industries, several useful recommendations for improving the thermo-mechanics' behavior of structural concrete panels are presented.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.128-136
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• 2007

Since the multi-view video is a set of video sequences captured by multiple array cameras for the same three-dimensional scene, it can provide multiple viewpoint images using geometrical manipulation and intermediate view generation. Although multi-view video allows us to experience more realistic feeling with a wide range of images, the amount of data to be processed increases in proportion to the number of cameras. Therefore, we need to develop efficient coding methods. One of the possible approaches to multi-view video coding is to generate an intermediate image using view interpolation method and to use the interpolated image as an additional reference frame. The previous view interpolation method for multi-view video coding employs fixed size block matching over the pre-determined disparity search range. However, if the disparity search range is not proper, disparity error may occur. In this paper, we propose an efficient view interpolation method using initial disparity estimation, variable block-based estimation, and pixel-level estimation using adjusted search ranges. In addition, we propose a multi-view video coding method based on H.264/AVC to exploit the intermediate image. Intermediate images have been improved about $1{\sim}4dB$ using the proposed method compared to the previous view interpolation method, and the coding efficiency have been improved about 0.5 dB compared to the reference model.

• Smart Structures and Systems
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• v.4 no.2
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• pp.221-232
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• 2008

This paper represents the final results of a research program sponsored by the European Commission through project WIND-CHIME ($\underline{W}$ide Range Non-$\underline{IN}$trusive $\underline{D}$evices toward $\underline{C}$onservation of $\underline{HI}$storical Monuments in the $\underline{ME}$diterranean Area), in which the possibility of using advanced seismic protection technologies to preserve historical monuments in the Mediterranean area is investigated. In the current research, the dynamic characteristics of two outstanding Mamluk-Style minarets, which similar minarets were reported to experience extensive damage during Dahshur 1992 earthquake, are investigated. The first minaret is the Qusun minaret (1337 A.D, 736 Hijri Date (H.D)) located in El-Suyuti cemetery on the southern side of the Salah El-Din citadel. The minaret is currently separated from the surrounding building and is directly resting on the ground (no vaults underneath). The total height of the minaret is 40.28 meters with a base rectangular shaft of about 5.42 ${\times}$ 5.20 m. The second minaret is the southern minaret of Al-Sultaniya (1340 A.D, 739 H.D). It is located about 30.0 meters from Qusun minaret, and it is now standing alone but it seems that it used to be attached to a huge unidentified structure. The style of the minaret and its size attribute it to the first half of the fourteenth century. The minaret total height is 36.69 meters and has a 4.48 ${\times}$ 4.48 m rectangular base. Field investigations were conducted to obtain: (a) geometrical description of the minarets, (b) material properties of the minarets' stones, and (c) soil conditions at the minarets' location. Ambient vibration tests were performed to determine the modal parameters of the minarets such as natural frequencies and mode shapes. A $1/16^{th}$ scale model of Qusun minaret was constructed at Cairo University Concrete Research Laboratory and tested under free vibration with and without SMA wire dampers. The contribution of SMA wire dampers to the structural damping coefficient was evaluated under different vertical loads and vibration amplitudes. Experimental results were used along with the field investigation data to develop a realistic 3-D finite element model that can be used for seismic risk evaluation of the minarets. Examining the updated finite element models under different seismic excitations indicated the vulnerability of such structures to earthquakes with medium to high a/v ratio. The use of SMA wire dampers was found feasible for reducing the seismic risk for this type of structures.

• The Mathematical Education
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• v.47 no.2
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• pp.197-219
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• 2008

Unlike ordinary situations, deifinitions play a very important role in mathematics education in schools. Mathematical concepts have been mainly acquired by given definitions. However, according to didactical intentions, mathematics education in schools has employed mathematical concepts and definitions with less strict forms than those in pure mathematics. This research mainly discusses definitions used in geometry (promising) course in primary schools to cope with possibilities of creating misconception due to this didactical transformation. After analyzing problems with potential misconceptions, a survey was conducted $\underline{with}$ 80 primary school teachers in Jeju to investigate their recognitions in meaning of mathematical concepts in geometry and attitudes toward teaching. Most of the respondents answered they taught their students while they knew well about mathematical definitions in geometry but the respondents sometimes confused mathematical concepts of polygons and circles. Also, they were aware of problems in current mathematics textbooks which have explained figures in small topics (classes). Here, several suggestions are proposed as follows from analyzing teachers' recognitions and researches in mathematical viewpoints of definitions (promising) in geometric figures which have been adopted by current mathematics textbooks in primary schools from the seventh educational curriculum. First, when primary school students in their detailed operational stage studying figures, they tend to experience $\underline{a}$ collision between concept images acquired from activities to find out promising and concept images formed through promising. Therefore, a teaching method is required to lessen possibility of misconceptions. That is, there should be a communication method between defining conceptual definitions and Images. Second, we need to consider how geometric figures and their elements in primary school textbooks are connected with fundamental terminologies laying the foundation for geometrical definitions and more logical approaches should be adopted. Third, the consistency with studying geometric figures should be considered. Fourth, sorting activities about problems in coined words related to figures and way and time of their introductions should be emphasized. In primary schools mathematics curriculum, geometry has played a crucial role in increasing mathematical ways of thoughts. Hence, being introduced by parts from viewpoints of relational understanding should be emphasized more in textbooks and teachers should teach students after restructuring this. Mathematics teachers should help their students not only learn conceptual definitions of geometric figures in their courses well but also advance to rigid mathematical definitions. Therefore, that's why mathematics teachers should know meanings of concepts clearly and accurately.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.167-176
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• 2018

It is necessary to consider various geological parameters such as lithology, geological structure, earthquake, hydraulic geology, geochemistry, geological engineering, and geothermal in order to select potential sites for HLW(high-level radioactive waste) geological disposal. In particular, the geological lineament reflects the characteristics of various geological parameters and can be used as an important criterion for site selecting such as nuclear power plants and HLW repositories. In this paper, the Finnish lineament classification method for HLW disposal site selection through the lineament analysis was applied to the lineament data in the Korean peninsula. For this purpose, we used previous lineament data from the KIGAM(Korea Institute of Geoscience and Mineral Resources) and obtained new lineament data from the field geologists such as structural geologist, paleoseismologist, and geomorphologist. To ensure the reliability of the new lineament analysis data, we used high-resolution satellite images and hill-shade relief maps which were constructed by a digital elevation model. In the prevailing direction analysis from the acquired lineament data, the NNE-SSW direction was the most dominant, but the ENE-WSW and NNW-SSE directions also showed highly frequency depending on the experts. Applying the Finnish classification method, the geometrical development characteristics of the lineament corresponding to the Class 1 and 2 used for the wide-wide candidate site were compared. As a result of direction analysis for Class 1, the NNE-SSW direction was the most dominant and the WNW-ESE direction also showed a high frequency. In the case of Class 2, the NNE-SSW is the most prevalent and WNW-ESE or ENE-WSW direction also had highly frequency depending on the experts. Different lineament analysis results based on the same data are interpreted as a result of subjective experience and analytical criteria from the every experts. Therefore, it is necessary to establish integrated criteria and consider geophysical data for the publication of reliable nation-wide lineament map.

• MISULJARYO - National Museum of Korea Art Journal
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• v.96
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• pp.54-88
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• 2019

The Album of Complete Views of Seas and Mountains comprises sixty real scenery landscape paintings depicting Geumgangsan Mountain, the Haegeumgang River, and the eight scenic views of Gwandong regions, as well as fifty-one pieces of writing. It is a rare example in terms of its size and painting style. The paintings in this album, which are densely packed with natural features, follow the painting style of the Southern School yet employ crude and unconventional elements. In them, stones on the mountains are depicted both geometrically and three-dimensionally. Since 1973, parts of this album have been published in some exhibition catalogues. The entire album was opened to the public at the special exhibition "Through the Eyes of Joseon Painters: Real Scenery Landscapes of Korea" held at the National Museum of Korea in 2019. The Album of Complete Views of Seas and Mountains was attributed to Kim Eung-hwan (1742-1789) due to the signature on the final leaf of the album and the seal reading "Bokheon(painter's penname)" on the currently missing album leaf of Chilbodae Peaks. However, there is a strong possibility that this signature and seal may have been added later. This paper intends to reexamine the creator of this album based on a variety of related factors. In order to understand the production background of Album of Complete Views of Seas and Mountains, I investigated the eighteenth-century tradition of drawing scenic spots while travelling in which scenery of was depicted during private travels or official excursions. Jeong Seon(1676-1759), Sim Sa-jeong(1707-1769), Kim Yun-gyeom(1711-1775), Choe Buk(1712-after 1786), and Kang Se-hwang(1713-1791) all went on a journey to Geumgangsan Mountain, the most famous travel destination in the late Joseon period, and created paintings of the mountain, including Album of Pungak Mountain in the Sinmyo Year(1711) by Jeong Seon. These painters presented their versions of the traditional scenic spots of Inner Geumgangsan and newly depicted vistas they discovered for themselves. To commemorate their private visits, they produced paintings for their fellow travelers or sponsors in an album format that could include several scenes. While the production of paintings of private travels to Geumgangsan Mountain increased, King Jeongjo(r. 1776-1800) ordered Kim Eung-hwan and Kim Hong-do, court painters at the Dohwaseo(Royal Bureau of Painting), to paint scenic spots in the nine counties of the Yeongdong region and around Geumgangsan Mountain. King Jeongjo selected these two as the painters for the official excursion taking into account their relationship, their administrative experience as regional officials, and their distinct painting styles. Starting in the reign of King Yeongjo(r. 1724-1776), Kim Eung-hwan and Kim Hong-do served as court painters at the Dohwaseo, maintained a close relationship as a senior and a junior and as colleagues, and served as chalbang(chief in large of post stations) in the Yeongnam region. While Kim Hong-do was proficient at applying soft and delicate brushstrokes, Kim Eung-hwan was skilled at depicting the beauty of robust and luxuriant landscapes. Both painters produced about 100 scenes of original drawings over fifty days of the official excursion. Based on these original drawings, they created around seventy album leaves or handscrolls. Their paintings enriched the tradition of depicting scenic spots, particularly Outer Inner Geumgang and the eight scenic views of Gwandong around Geumgangsan Mountain during private journeys in the eighteenth century. Moreover, they newly discovered places of scenic beauty in the Outer Geungang and Yeongdong regions, establishing them as new painting themes. The Album of Complete Views of Seas and Mountains consists of four volumes. The volumes I, II include twenty-nine paintings of Inner Geumgangsan; the volume III, seventeen scenes of Outer Geumgangsan; and the volume IV, fourteen images of Maritime Geumgangsan and the eight scenic views of Gwandong. These paintings produced on silk show crowded compositions, geometrical depictions of the stones and the mountains, and distinct presentation of the rocky peaks of Geumgangsan Mountain using white and grayish-blue pigments. This album reflects the Joseon painting style of the mid- and late eighteenth century, integrating influences from Jeong Seon, Kang Se-hwang, Sim Sa-jeong, Jeong Chung-yeop(1725-after 1800), and Kim Hong-do. In particular, some paintings in the album show similarities to Kim Hong-do's Album of Famous Mountains in Korea in terms of its compositions and painterly motifs. However, "Yeongrangho Lake," "Haesanjeong Pavilion," and "Wolsongjeong Pavilion" in Kim Eung-hwan's album differ from in the version by Kim Hong-do. Thus, Kim Eung-hwan was influenced by Kim Hong-do, but produced his own distinctive album. The Album of Complete Views of Seas and Mountains includes scenery of "Jaundam Pool," "Baegundae Peak," "Viewing Birobong Peak at Anmunjeom groove," and "Baekjeongbong Peak," all of which are not depicted in other albums. In his version, Kim Eung-hwan portrayed the characteristics of the natural features in each scenic spot in a detailed and refreshing manner. Moreover, he illustrated stones on the mountains using geometric shapes and added a sense of three-dimensionality using lines and planes. Based on the painting traditions of the Southern School, he established his own characteristics. He also turned natural features into triangular or rectangular chunks. All sixty paintings in this album appear rough and unconventional, but maintain their internal consistency. Each of the fifty-one writings included in the Album of Complete Views of Seas and Mountains is followed by a painting of a scenic spot. It explains the depicted landscape, thus helping viewers to understand and appreciate the painting. Intimately linked to each painting, the related text notes information on traveling from one scenic spot to the next, the origins of the place names, geographic features, and other related information. Such encyclopedic documentation began in the early nineteenth century and was common in painting albums of Geumgangsan Mountain in the mid- nineteenth century. The text following the painting of Baekhwaam Hermitage in the Album of Complete Views of Seas and Mountains documents the reconstruction of the Baekhwaam Hermitage in 1845, which provides crucial evidence for dating the text. Therefore, the owner of the Album of Complete Views of Seas and Mountains might have written the texts or asked someone else to transcribe them in the mid- or late nineteenth century. In this paper, I have inferred the producer of the Album of Complete Views of Seas and Mountains to be Kim Eung-hwan based on the painting style and the tradition of drawing scenic spots during official trips. Moreover, its affinity with the Handscroll of Pungak Mountain created by Kim Ha-jong(1793-after 1878) after 1865 is another decisive factor in attributing the album to Kim Eung-hwan. In contrast to the Album of Famous Mountains in Korea by Kim Hong-do, the Album of Complete Views of Seas and Mountains exerted only a minor influence on other painters. The Handscroll of Pungak Mountain by Kim Ha-jong is the sole example that employs the subject matter from the Album of Complete Views of Seas and Mountains and follows its painting style. In the Handscroll of Pungak Mountain, Kim Ha-jong demonstrated a painting style completely different from that in the Album of Seas and Mountains that he produced fifty years prior in 1816 for Yi Gwang-mun, the magistrate of Chuncheon. He emphasized the idea of "scholar thoughts" by following the compositions, painterly elements, and depictions of figures in the painting manual style from Kim Eung-hwan's Album of Complete Views of Seas and Mountains. Kim Ha-jong, a member of the Gaeseong Kim clan and the eldest grandson of Kim Eung-hwan, is presumed to have appreciated the paintings depicted in the nature of Album of Complete Views of Seas and Mountains, which had been passed down within the family, and newly transformed them. Furthermore, the contents and narrative styles of Yi Yu-won's writings attached to the paintings in the Handscroll of Pungak Mountain are similar to those of the fifty-one writings in Kim Eunghwan's album. This suggests a possible influence of the inscriptions in Kim Eung-hwan's album or the original texts from which these inscriptions were quoted upon the writings in Kim Ha-jong's handscroll. However, a closer examination will be needed to determine the order of the transcription of the writings. The Album of Complete View of Seas and Mountains differs from Kim Hong-do's paintings of his official trips and other painting albums he influenced. This album is a siginificant artwork in that it broadens the understanding of the art world of Kim Eung-hwan and illustrates another layer of real scenery landscape paintings in the late eighteenth century.