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Case study of the mining-induced stress and fracture network evolution in longwall top coal caving

  • Li, Cong;Xie, Jing;He, Zhiqiang;Deng, Guangdi;Yang, Bengao;Yang, Mingqing
    • Geomechanics and Engineering
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    • v.22 no.2
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    • pp.133-142
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    • 2020
  • The evolution of the mining-induced fracture network formed during longwall top coal caving (LTCC) has a great influence on the gas drainage, roof control, top coal recovery ratio and engineering safety of aquifers. To reveal the evolution of the mining-induced stress and fracture network formed during LTCC, the fracture network in front of the working face was observed by borehole video experiments. A discrete element model was established by the universal discrete element code (UDEC) to explore the local stress distribution. The regression relationship between the fractal dimension of the fracture network and mining stress was established. The results revealed the following: (1) The mining disturbance had the most severe impact on the borehole depth range between approximately 10 m and 25 m. (2) The distribution of fractures was related to the lithology and its integrity. The coal seam was mainly microfractures, which formed a complex fracture network. The hard rock stratum was mainly included longitudinal cracks and separated fissures. (3) Through a numerical simulation, the stress distribution in front of the mining face and the development of the fracturing of the overlying rock were obtained. There was a quadratic relationship between the fractal dimension of the fractures and the mining stress. The results obtained herein will provide a reference for engineering projects under similar geological conditions.

Eddy Kinetic Energy in the East Sea Estimated from Topex/Poseidon Altimeter Measurements

  • Cho Kwangwoo;Cho Kyu-Dae
    • Fisheries and Aquatic Sciences
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    • v.5 no.3
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    • pp.219-228
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    • 2002
  • Based on the five-year (October 1992 through September 1997) Topex/Poseidon altimeter measurements, we describe the statistical characteristics of the eddy variability in the East Sea in terms of sea surface height anomaly, slope variability, and eddy kinetic energy (EKE). The sea surface height anomalies in the East Sea are produced with standard corrections from Topex/Poseidon measurements. In order to eliminate the high frequency noise in the sea surface height anomaly data, the alongtrack height anomaly data was filtered by about 40 km low-pass Lanczos filter based on Strub et al. (1997) and Kelly et a1. (1998). We find that there exists a distinct spatial contrast of high eddy variability in the south and low eddy energy in the north, bordering the Polar Front. In the northwestern area $(north\;of\;39^{\circ}N\;and\;west\;of\;133^{\circ}E)$ from the Polar Front where the eddies frequently appear, the EKE is also considerabel. The high kinetic energy in the southern East Sea reveals a close connection with the paths of the Tsushima Warm Current, suggesting that the high variability in the south is mainly generated by the baroclinic instability process of the Tsushima Warm Current. This finding is supported by other studies (Fu and Zlontnicki, 1989; Stammer, 1997) wh.ch have shown the strong eddy energy coupled in the major current system. The monthly variation of the EKE in both areas of high and low eddy variability shows a strong seasonality of a high eddy kinetic energy from October to February and a relatively low one from March to September. The sequential pattern of wind stress curl shows resemblance with those of monthly and seasonal EKE and the two sequences have a correlation of 0.82 and 0.67, respectively, providing an evidence that wind stress curl can be the possible forcing for the monthly and seasonal variation of the EKE in the East Sea. The seasonality of the EKE also seems to correlate with the seasonality of the Tsushima Warm Current. There also exists the large spatial and interannual variabilities in the EKE.

Impact of the Variation of Sea Breeze Penetration due to Terrain Complexity on PBL Development (해안지형의 복잡성에 따른 해풍침투 변화가 대기경계층에 미치는 영향 분석)

  • Park, Soon-Young;Lee, Hwa-Woon;Lee, Soon-Hwan;Lee, Kwi-Ok;Ji, Hyo-Eun
    • Journal of Environmental Science International
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    • v.20 no.2
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    • pp.275-289
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    • 2011
  • In order to clarify the relation between sea breeze penetration and Planetary Boundary Layer development in southeastern part of the Korean Peninsula, several numerical assessments were carried out using atmospheric numerical model WRF(Weather Research and Forecasting). Compared with onset time of sea breeze at eastern coast area(Uljin), the time at southern coast region(Masan) with complex costal line tend to delay for several hours. The penetration patterns of sea breeze between two coastal regions are some different due to the shape of their coastal line and back ground topography. Intensified valley wind due to high topography of lee side of Uljin can help penetration of sea breeze at early time. So penetration of sea breeze at early time often prevent PBL to develop at Uljin and lower PBL height last for a day time. But because of late penetration of sea breeze at Masna, PBL Height dramatically decrease after 1500LST. The distribution of front genesis function based on the heat and momentum variation are explained obviously the sea breeze penetration patterns and agreed well with the PBL height distribution.

Development of a Sizing System and a Draping Pattern for Hip Protector based on 3D Data Analysis of Korean Older Women (한국 노인의 3D 인체특성 분석을 통한 Hip protector 치수체계 수립 및 입체패턴 설계)

  • Jeon, Eun-Jin;Park, Sei-Kwon;You, Hee-Cheon;Kim, Hee-Eun
    • Fashion & Textile Research Journal
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    • v.18 no.1
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    • pp.120-129
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    • 2016
  • This study aimed to develop an optimal sizing system and a draping pattern for hip protector based on an analysis of anthropometric characteristics of Korean older women. A hip protector is a specialized form of pants or underwear containing pads along the outside of each hip. The 3D body scan data of Korean older women were analyzed to identify their anthropometric characteristics and a four-size system with 93% of population accommodation was developed by clustering analysis based on key dimensions derived from factor analysis. The sizing system consists of small/short, large/short, small/tall, and large/tall. A 3D physical model and hip pads were fabricated; then, a hip protector was draped on the 3D model and hip pads. The sizing system of hip protector was analyzed in terms of size and shape and a draping pattern was compared on back center, back side, front side, front center and pad. Lastly, the pattern deformation and clothing pressure were analyzed using the virtual clothing system CLO. Virtual system have disadvantage of not to suggest the objective value. In the future research the wearing comfort and impact absorption of the hip protector needs to be tested and then a hip protector design will be finalized by considering the hip protector's size, material, comfort testing results, aesthetic appeal, protection effectiveness, and practical utility of everyday use.

A study on the transition of the Hungarian men's costume (헝가리 남성복식 변천에 대한 연구)

  • Cho, Hyunjin
    • The Research Journal of the Costume Culture
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    • v.24 no.1
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    • pp.54-66
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    • 2016
  • This paper examines the transition of the Hungarian men's costume. Transition of the Hungarian men's costume can be divided into pre-eighteenth century, eighteenth century, and since the nineteenth century. Hungarian costume was derived from the Magyar who settled in Hungary in the ninth century. Hungry had begun to accept Western culture in the tenth century, so when the prototype of Hungarian costume was completed, it consisted of Dolman, Mente, pants, and boots combining traditional Magyar style with Western European style. In particular, Dolman shows the uniqueness of the Hungarian men's costume; it has a high, stand-up collar in the back center, closes on the left, has a right front plate with a diagonal cut at the waist, and a wide front closure. In the eighteenth century, Hungarian men's costumes played an important role in displaying national pride while living under the oppression of the Habsburg Empire. In particular, Dolman was worn as a uniform at the battle of independence (1703~1710). This dress of male courtiers became the distinctive style of the eighteenth century and then became the basic style of men's costumes. Since the nineteenth century, Hungarian men's costumes have acted as an means to promote the national consciousness of Hungary through the Citizen Revolution (1848), the War of Independence (1849), and the formation of the Dual Empire (1867). Looking at evolution of the Hungarian men's dress style, it reveals that resistance and struggles against other nations, a history of aggression, and living under oppressed are factors that impact on important clothing transitions.

Multilateral Nuclear Approaches (MNAs), Factors and Issues Lessons from IAEA Study to Regional Cooperation (다자간 원자력 협력: 요소와 현안)

  • Hwang Yong-Soo
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2005.06a
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    • pp.56-66
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    • 2005
  • In response to the increasing emphasis being placed on the importance of international cooperation as part of global efforts to cope with growing non proliferation, and security, concerns in the nuclear field, the Director General of the International Atomic Energy Agency (IAEA), Mohamed ElBaradei, appointed an international group of experts to consider possible multilateral approaches to the nuclear fuel cycle. The mandate of the Expert Group was three fold: ${\bullet}$ To identify and provide an analysis of issues and options relevant to multilateral approaches to the front and back ends of the nuclear fuel cycle; ${\bullet}$ To provide an overview of the policy, legal, security, economic, institutional and technological incentives and disincentives for cooperation in multilateral arrangements for the front and back ends of the nuclear fuel cycle; and ${\bullet}$ To provide a brief review of the historical and current experiences and analyses relating to multilateral fuel cycle arrangements relevant to the work of the Expert Group. The overall purpose was to assess MNAs in the framework of a double objective: strengthening the international nuclear non proliferation regime and making the peaceful uses of nuclear energy more economical and attractive. The Group identifies options for MNAs - options in terms of policy, institutional and legal factors - for those parts of the nuclear fuel cycle of greatest sensitivity from the point of view of proliferation risk. It also reflects the Groups deliberations on the corresponding benefits and disadvantages (pros and cons) of the various options and approaches. Although the Expert Group was able to agree to forward the resulting report to the Director General, it is important to note that the report does not reflect agreement by all of the experts on any of the options, nor a consensus assessment of their respective value. It is intended only to present options for MNAs, and to reflect on the range of considerations which could impact on the desirability and feasibility of those options.

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A Study of Sleeve Cap in the Knitwears with Plain Stitch (Plain 조직 니트 의류의 소매산 형태 연구)

  • Hong Soo-Sook;Suh Mi-A
    • The Research Journal of the Costume Culture
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    • v.14 no.3 s.62
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    • pp.404-417
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    • 2006
  • The purpose of this thesis, therefore, is to examine the shaping methods and the knitting drafts of sleeve cap in the knitwears which are currently used by the manufacturers; to study the curve forms of sleeves in knitwears by analyzing synthetically the results of investigating the problems of knit wear sleeves; to present the most suitable sleeve cap for the knitwears. As the studying methods, I collected the basic data from the working-level persons of knit wear manufacturers, examined the knitting draft in the knitwears, and from that, made three kinds of comparative experimental garments and one kind of research experimental one as 10G and 16G. In doing so, I showed the sleeve cap suitable for the knitwears with plain stitch after operating sensual evaluation with Liker's 5-point rating measure. The analysis of data was handled with statistics by using SPSS Ver. 12.0; the method of statistics was executed by Frequency Analysis, Trust Analysis, one-way ANOVA, and Duncan test according to each topic of the research. As the result of the sensual evaluation of the experimental garments produced from the study, the research experimental garment looks better than the comparative experimental one in both 10G and l6G; has less extra folds around the front part of sleeve cap; looks more natural in sleeve caps of the body part and of a sleeve. From this, I am able to figure out that the research experimental garment looks better than the comparative experimental one produced by knit wear manufacturers. In addition, I can come to know that the different knitting of the front line and the back one of armhole in the knitwears has a favorable impact on improving the appearance of a sleeve.

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A Validated Solution for the Threat of Ionosphere Spatial Anomalies to Ground Based Augmentation System Users

  • Pullen, Sam;Lee, Ji-Yun;Datta-Barua, Seebany;Park, Young-Shin;Zhang, Godwin;Enge, Per
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.1
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    • pp.9-14
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    • 2006
  • This paper develops a complete methodology for the mitigation of ionosphere spatial anomalies by GBAS systems fielded in the Conterminous U.S. (CONUS). It defines an ionosphere anomaly threat model based on validated observations of unusual ionosphere events in CONUS impacting GBAS sites in the form of a linear ‘wave front’ of constant slope and velocity. It then develops a simulation-based methodology for selecting the worst-case ionosphere wave front impact impacting two satellites simultaneously for a given GBAS site and satellite geometry, taking into account the mitigating effects of code-carrier divergence monitoring within the GBAS ground station. The resulting maximum ionosphere error in vertical position (MIEV) is calculated and compared to a unique vertical alert limit, or $VAL_{H2,I}$, that applies to the special situation of worst-case ionosphere gradients. If MIEV exceeds $VAL_{H2,I}$ for one or more otherwise-usable subset geometries (i.e., geometries for which the 'normal' vertical protection level, or $VPL_{H0}$, is less than the 'normal' VAL), the broadcast ${\sigma}_{pr_{-}gnd}$ and/or ${\sigma}_{vig}$ must be increased such that all such potentially-threatening geometries have VPL$_{H0}$ > VAL and thus become unavailable. In addition to surveying all aspects of the methods used to generate the required ${\sigma}_{pr_{-}gnd}$ and ${\sigma}_{vig}$ inflation factors for CONUS GBAS sites, related methods for deriving similar results for GBAS sites outside CONUS are suggested.

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Application of Finite Element Analysis for Structural Stability Evaluation of Modern and Contemporary Sculptures: 'Eve 58-1' by Man Lin Choi

  • Kwon, Hee Hong;Shin, Jeong Ah;Cho, Nam Chul
    • Journal of Conservation Science
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    • v.38 no.4
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    • pp.277-288
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    • 2022
  • 'Eve 58-1', the subject of this study is a statue made of plaster and its structural stability was evaluated by utilizing the CAE program in order to prevent the risk of damage arising from impact and vibration that are generated during the packaging and transportation process given its material characteristics. CAE is an abbreviation for Computer Applied Engineering for realization by predicting changes at the time of application of virtual physical energy. It is applied by reflecting the physical property conditions and each boundary condition of plaster, and the digital images of the internal and external structure of the work were acquired through 3D scanning and CT analysis for interpretation by executing finite element modeling. When acceleration is applied to the work in the direction of its own weight, the left-right side and the front-rear side, it was possible to confirm a maximum displacement value of 15.24 mm in the head section of the front-rear side direction that has been tilted by approximately 27° from the Y-axis and the largest stress value of 12.46 MPa was at the left ankle section. The corresponding results confirmed that the left ankle section is the most vulnerable area and the section for which precautions need to be exercised and supplemented at the time of transporting the work by means of objective values.

A study on the location of Donghwa temple from feng-shui perspective (팔공산(八公山) 동화사(桐華寺)의 풍수(風水) 및 가람배치( 伽藍配置)의 특징(特徵))

  • Sung, Dong-Hwan
    • Journal of the Korean association of regional geographers
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    • v.7 no.4
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    • pp.65-80
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    • 2001
  • The purpose of this study is to examine the characteristics of the location and the layout of Donghwa temple(桐華寺) in Kyungbuk Province from feng-shui perspective. Feng-shui is a traditional geographic thought in China and Korea. It is necessary to understand feng-shui in order to understand Korean landscape and cultural geography. Feng-shui had had a tremendous impact on Korean landscape through selective buildings of cities, settlements, houses, monuments, temples, pagodas, and so on. In this study, I interpret the geomantic characteristics of Dinghwa temple in Kyungbuk Province. The results of this study are as follow. 1) Donghwa temple is carrying the mountain on the back and belting the water in front. The mountains which encircle the auspicious place are accordance with the feng-shui theory. The watercourse which flows the temple is suitable. The feng-shui spot is located at the foot of the mountain with surrounding mountains and a watercourse in front. 2) Many feng-shui texts discuss the types of surrounding mountain in detail and morphologically describe them with certain auspicious objects. In case of Donghwa temple, it can be compared to a phoenix carrying eggs in the bosom. This is a morphological marker for the description of configulation features of Donghwa temple. In the case of Donghwa temple, we can observe geomantic landscape for the purpose of fulfilling the geomantic harmony of the temple. Also the impact of feng-shui on vegetation is identified in Donghwa temple. 3) For the management of good feng-shui condition, and for the maintaining the harmony between the building layout and surrounding landform, some proposals are suggested.

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