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Reliability Improvement of Offshore Structural Steel F690 Using Surface Crack Nondamaging Technology

  • Lee, Weon-Gu;Gu, Kyoung-Hee;Kim, Cheol-Su;Nam, Ki-Woo
    • Journal of Ocean Engineering and Technology
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    • v.35 no.5
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    • pp.327-335
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    • 2021
  • Microcracks can rapidly grow and develop in high-strength steels used in offshore structures. It is important to render these microcracks harmless to ensure the safety and reliability of offshore structures. Here, the dependence of the aspect ratio (As) of the maximum depth of harmless crack (ahlm) was evaluated under three different conditions considering the threshold stress intensity factor (Δkth) and residual stress of offshore structural steel F690. The threshold stress intensity factor and fatigue limit of fatigue crack propagation, dependent on crack dimensions, were evaluated using Ando's equation, which considers the plastic behavior of fatigue and the stress ratio. ahlm by peening was analyzed using the relationship between Δkth obtained by Ando's equation and Δkth obtained by the sum of applied stress and residual stress. The plate specimen had a width 2W = 12 mm and thickness t = 20 mm, and four value of As were considered: 1.0, 0.6, 0.3, and 0.1. The ahlm was larger as the compressive residual stress distribution increased. Additionally, an increase in the values of As and Δkth(l) led to a larger ahlm. With a safety factor (N) of 2.0, the long-term safety and reliability of structures constructed using F690 can be secured with needle peening. It is necessary to apply a more sensitive non-destructive inspection technique as a non-destructive inspection method for crack detection could not be used to observe fatigue cracks that reduced the fatigue limit of smooth specimens by 50% in the three types of residual stresses considered. The usefulness of non-destructive inspection and non-damaging techniques was reviewed based on the relationship between ahlm, aNDI (minimum crack depth detectable in non-destructive inspection), acr N (crack depth that reduces the fatigue limit to 1/N), and As.

The Analysis of Mathematical Tasks for developing the core competencies in High School "Mathematics" textbook (고등학교 <수학>교과서에 제시된 교과 역량 과제 분석)

  • Choi, Heesun
    • Journal of the Korean School Mathematics Society
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    • v.22 no.2
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    • pp.95-113
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    • 2019
  • In this paper, we analyzed the levels of cognitive demand of the tasks for developing t he mathematical core competencies presented in the "Mathematics" textbook of the first y ear of high school developed according to the 2015 revised mathematics curriculum. "Mathematics" textbook included 4999 mathematics tasks, of which 703 were tasks for developing the mathematical competency. Analysis of 703 mathematical tasks according to the analysis framework of Stein, Smith, Henningsen, and Silver (2000) showed that 61.5% of students required high cognitive levels, 38.5% required low cognitive levels, and the types of tasks were as follows: Low-M 1.0%, Low-P 37.5%, High-P 57.8%, High-D 3.7%. It w as found that most of the tasks for the purpose were tasks that led to understanding mathematical concepts, principles, and processes along procedural processes.

A Postnationalist Critique of Irish Nation-State Ideology in Patrick Kavanagh's The Great Hunger (패트릭 캐바나의 『대기근』에 나타난 포스트민족주의 -아일랜드 민족국가 이데올로기 비판)

  • Kim, Yeonmin
    • Journal of English Language & Literature
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    • v.60 no.2
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    • pp.315-338
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    • 2014
  • In The Great Hunger (1942) Patrick Kavanagh opens an Irish postnationalist discourse. Taking advantage of historical revisionism and postcolonialism, he not only demystifies a romantic nationalist ideology rooted in rural Ireland but also searches for an autonomous literary tradition free of the Irish Literary Revival, supposedly an outcome of a colonial influence. As a farmer-poet, Kavanagh deconstructs in two ways myths of rural areas, to which the Revivalists aspire. Contrary to Revivalism, he reveals that rural Ireland is not an idealized place where national identity arises and individual spirits are restored. It is instead a cruel place where farmer Maguire, deprived of health, wealth, and love, is tortured by hard labor in the field, moral regulations imposed by the Church, and his mother's domestic authority, all of which leave him unmarried until age sixty-five. Kavanagh also challenges the Revivalist tradition, led by W. B. Yeats commonly referred to as the poet of the nation, by indicting its reliance on former colonial authority and its lack of a sense of communal autonomy, both of which are diagnosed as "provincialism" by Kavanagh. Given that modern Irish literature has been strongly colored as nationalistic during the course of anticolonial resistance, Kavanagh's critique of the Revival in The Great Hunger, whose proponents blindly beautify the lives of farmers, runs directly against the grain of the founding ideology of the Irish nation-state. His voice, like that of a whistle-blower, disclosing the harsh realities of rural Ireland, ushers in a "post"-nationalist perspective on nation and national myths in Irish poetics.

Characteristics of Fashion Memes in Vetements based on the Playfulness of Mikhail Bakhtin's Carnival Theory (미하일 바흐친(Mikhail Bakhtin) 카니발이론의 유희성을 중심으로 본 베트멍(Vetements)의 패션 밈 특성)

  • Yun, Jiae;Park, Hyewon
    • Journal of Fashion Business
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    • v.25 no.2
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    • pp.1-17
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    • 2021
  • The development of the Internet has led to the emergence of an internet meme culture using duplication. This phenomenon has appeared in the fashion field as 'fashion memes' and its playful expression has helped it to spread. Vetements is one of the well-known brands that actively incorporates fashion memes into their fashion. The purpose of this study was to examine the playfulness of Mikhail Bakhtin's Carnival Theory and identify the playful identity, design characteristics, and implications of Vetements' fashion memes in light of Bakhtin's playfulness. The research methods were literature research and collection case analysis, and empirical content research was conducted in parallel. The scope of this study was fashion memes shown in the products from 2017 S/S to 2019 F/W. The study results showed that Bakhtin's playfulness could be divided into "playfulness in the destruction of hierarchy", "playfulness in grotesque imagery" and "playfulness in the emphasis on the lower bodily stratum". Based on these findings, the playful identity of Vetements' fashion meme images can be described as follows. First, it breaks down the existing order of fashion brands like the destruction of hierarchy in Bakhtin's theory. Second, it is grotesque; it is strange, eerie, yet ridiculous at the same time. Third, it is a playful metaphor of contamination, filth, and lower stratum. The modes of embodiment of such identity include Vetements' collaboration with famous brands, the use of cheap items, and the expression of genderless ideas.

Removal Potential of Particulate Matter of 12 Woody Plant Species for Landscape Planting

  • Kwon, Kei-Jung;Urrintuya, Odsuren;Kim, Sang-Yong;Yang, Jong-Cheol;Sung, Jung-Won;Park, Bong-Ju
    • Journal of People, Plants, and Environment
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    • v.23 no.6
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    • pp.647-654
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    • 2020
  • Background and objective: Particulate matter (PM) is one of the serious environmental problems and threatens human health. Plants can clean the air by removing PM from the atmosphere. This study was carried out to investigate the PM removal efficiency of 12 species of woody plants. Methods: Actinidia arguta, Dendropanax morbiferus, Fraxinus rhynchophylla, Parthenocissus tricuspidata, Pittosporum tobira, Rhaphiolepis indica, Rhapis, Salix integra, Salix koreensis, Schisandra chinensis, Viburnum odoratissimum var. awabuki, and Vitis coignetiae were used as plant material. Six 15 cm (D) pots were placed in an acrylic chamber of 800 (D) × 800 (W) × 1000 (H) mm. The LED panel was used as a light source. The reduction of PM10, PM2.5, and PM1 for 300 minutes after the injection of PM was automatically measured. Results: The leaf area and the amount of PM in the chamber showed a negative correlation. 12 species of plants were compared by dividing the plants into 3 groups according to their characteristics: vines, trees, and shrubs and small trees. In the vine plant group, the averages of PM10, PM2.5, and PM1 were 7.917%, 8.796%, and 30.275%, respectively. In the shrubs and small trees group, the average of PM10, PM2.5, and PM1 were 10.142%, 11.133%, and 36.448%, respectively. In the trees group, the average of PM10, PM2.5, and PM1 were 11.475%, 12.892%, and 40.421%, respectively. When the initial concentration was 100%, PM10, PM2.5, and PM1 of Viburnum odoratissimum var. awabuki with the largest leaf area were 5.6%, 6.3%, and 21.0% after 5 hours, respectively, the best results among 12 species of plants. Conclusion: The vine plant group was more effective in removing PM than the other two groups. In the tree groups, the fact that the leaf development was relatively inactive at a plant height of 30 cm was considered to have an effect on the removal of particulate matter.

Effect of Novel High-Intensity Ultrasound Technique on Physio-Chemical, Sensory Attributes, and Microstructure of Bovine Semitendinosus Muscle

  • Eun Yeong Lee;Dhanushka Rathnayake;Yu Min Son;Allah Bakhsh;Young Hwa Hwang;Jeong Keun Seo;Chul Beom Kim;Seon Tea Joo
    • Food Science of Animal Resources
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    • v.43 no.1
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    • pp.85-100
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    • 2023
  • The present study aimed to evaluate the effects of high-intensity ultrasound (HIU) application on meat quality traits, sensory parameters, and the microstructure of semitendinosus muscle from Hanwoo cattle. The samples were treated in an ultrasonic bath (35 kHz) at an intensity of 800 W/cm2 for 60 min, followed by aging at 1℃ for 0, 3, and 7 days. The application of ultrasound resulted in lower Warner-Bratzler shear force and higher myofibrillar fragmentation index values during the storage period. HIU also enhanced the tenderness, flavor, umami, and overall acceptability of cooked beef muscle. However, the electronic tongue evaluation results showed higher umami values in the control treatment on the seventh day of storage. The microstructure of sonicated meat showed disorganized myofibrillar architecture and swelling in the A-band region of sarcomeres during the storage period, which led to greater meat tenderness. The heatmap illustrated the high abundance of α-linolenic acid (C20:5n3) and eicosapentaenoic acid (C18:3n3) in sonicated meat samples on the third day of the storage. These results showed that HIU is a potential method for tenderizing and improving the sensory attributes of beef without compromising other quality aspects.

Evaluation of Reverse Electrodialysis based on the Number of Cell Pairs and Stack Size Using Patterned Ion Exchange Membrane (패턴형 이온교환막을 이용한 스택의 셀 수 및 크기에 따른 역전기투석 성능 평가)

  • Dong-Gun Lee;Hanki Kim;Namjo Jeong;Young Sun Mok;Jiyeon Choi
    • New & Renewable Energy
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    • v.19 no.2
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    • pp.31-39
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    • 2023
  • Salinity gradient energy can be generated from a mixture of water streams with different salt concentrations by using reverse electrodialysis (RED). In this study, we evaluated the effect of stack size and number of cell pairs on the energy efficiency and specific energy of the RED process. Additionally, we studied the prementioned parameters to maximize the power density of RED. The performance of the RED stack which used a patterned ion exchange membrane, was evaluated as a function of stack size and feed flow rate. Moreover, it was noted that an increase in stack size increased the ion movement through the ion exchange membrane. Furthermore, an increase in feed flow rate led to a reduction in the concentration variation, resulting in an increase in OCV and power density. The energy efficiency and specific energy for 100 cells in the 10 × 10 cm2 stack were the highest at 12% and 0.05 kWh/m3, respectively, while the power density from 0.33 cm/s to 5 × 5 cm2 stack was the highest at 0.53 W/m2. The study showed that the RED performance can be improved by altering the size of the stack and the number of cell pairs, thereby positively affecting energy efficiency and specific energy.

Thermal analysis and optimization of the new ICRH antenna Faraday Screen in EAST

  • Q.C. Liang ;L.N. Liu ;W. Zhang ;X.J. Zhang ;S. Yuan ;Y.Z. Mao ;C.M. Qin;Y.S. Wang ;H. Yang
    • Nuclear Engineering and Technology
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    • v.55 no.7
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    • pp.2621-2627
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    • 2023
  • In Experimental Advanced Superconducting Tokamak (EAST) experiments, to achieve long pulse and high-power ICRH system operation, a new kind of ICRH antenna has been designed. One of the most critical factors in limiting the operation of long pulse and high power is the intense heat load in the front face of the ICRH antenna, especially the Faraday Screen (FS). Therefore, the cooling channels of FS need to be designed. According to thermal-hydraulic analysis, the FS tubes are divided into several groups to achieve more excellent water cooling capability. The number of series and parallel tubes in one group is chosen as six. This antenna went into service in the spring of 2021, and it is delightful that the temperature distribution of the FS tube is below 400 ℃ in 14.5 s and 1.8 MW ICRH system operation. However, the active water-cooling design was not carried out on the upper and lower plates of FS, which led to severe ablations on that region under long pulse and high power operation, and the temperature is up to 800. Therefore, the upper and lower side plates of the FS were designed with water cooling based on thermal-hydraulic analysis. During the 2022 winter experiments, the temperature of ICRH antenna FS was lower than 400 in the pulse of 200s and the power of 1 MW operation.

Study on the Operational Status of the Comprehensive Rural Village Development Project Completion Area - Focused on Sumun, Obong and Mopyeong Areas - (농촌마을종합개발사업 준공 권역의 운영 실태에 관한 고찰 - 수문·오봉·모평권역을 중심으로 -)

  • Yang, Won Sik;Choi, Young-Wan;Kim, Young-Joo
    • Journal of Korean Society of Rural Planning
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    • v.30 no.1
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    • pp.67-79
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    • 2024
  • The Comprehensive Rural Village Development Project, a resident-led bottom-up regional development project, began in 2004. This study investigated difficulties and problems in the operation process after the completion of the project, and future improvement plans, through in-depth interviews with the former and current chairman of the steering committee, steering committee members, and office managers, targeting three regions in Jeollanam-do, 15 years after the completion of the project. As a result of the survey and analysis, it was effective in improving the living environment and characteristics of each village and revitalizing the area. And while there were well-run facilities depending on the type of project, there were also many idle facilities. In the case of communal facilities, there was a high possibility of problems in operation and management when the scale of the new building was large. Conflicts occurred between villages in the process of independently operating the area after the completion of the project. Therefore, it is necessary to provide an S/W project program to prepare for after completion. Local governments need to utilize City and County Capacity Enhancement Projects to support regional leaders to participate in educational programs after completion and provide guidance and supervision for village operations.

Surgical Management of Pachyonychia Congenita in a 3-Year-Old

  • Jack D. Sudduth;Christopher Clinker;Matthew Holdaway;Jessica L. Marquez;Jacob Veith;Thomas Wright;W. Bradford Rockwell
    • Archives of Plastic Surgery
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    • v.50 no.6
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    • pp.573-577
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    • 2023
  • Pachyonychia congenita is a rare genetic disorder characterized by hypertrophic nail plates, hyperkeratotic nail beds, and thickened hyponychium of the fingers and toes, impairing manual dexterity and resulting in poor aesthetics. The current body of literature describes various treatment modalities, but no singular approach has been defined as the gold standard. In this case, the authors employed different surgical techniques for treating pachyonychia congenita to evaluate the most effective approach. A 3-year-old boy presented with hypertrophic nail growth involving all digits of both hands and feet. Three surgical procedures were performed on the patient's fingers and toes using germinal matrix excision (GME) alone, GME plus partial sterile matrix excision (pSME), or GME plus complete sterile matrix excision (cSME). The digits treated with GME + cSME exhibited no recurrence of nail growth. Those treated with GME alone exhibited recurrence of hypertrophic nail growth, although their growth slowed. Excision of GME + cSME prevented recurrence of hypertrophic nails, while GME alone or with pSME led to slower-growing hypertrophic nails. Complete excision of the germinal and sterile matrices with skin graft closure may be a definitive treatment for pachyonychia congenita, but further studies are needed to validate these findings.