• Title/Summary/Keyword: slits

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The Structure of Three-dimensional Turbulent Flow Fields of a Cone Type Gas Swirl Burner (콘형 가스 스월버너의 3차원 난류 유동장 구조)

  • Kim, J.K.;Jeong, K.J.
    • Journal of Power System Engineering
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    • v.5 no.2
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    • pp.22-29
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    • 2001
  • This paper represents axial mean velocity, turbulent kinetic energy and swirl number based on momentum flux measured in the X-Y plane and Y-Z plane respectively of a cone type gas swirl burner by using X-probe from the hot-wire anemometer system. This experiment is carried out at flow rates 350 and $450{\ell}/min$ respectively, which are equivalent to the combustion air flow rate necessary for heat release 15,000 kcal/hr in gas furnace, in the test section of a subsonic wind tunnel. Axial mean velocities and turbulent kinetic energies show that their maximum values exist centering around narrow slits situated radially on the edge of and in the forefront of a burner until $X/R{\fallingdotseq}1.5$, but they have a peculiar shape like a starfish diffusing and developing into inward and outward of a burner by means of the mixing between flows ejected from narrow slits, an inclination baffle plate and swirl vanes respectively according to downstream regions. Moreover, they show a relatively large value in the inner region of 0.5$S_m$ obtained by integration of velocity profiles shows a characteristic that has an inflection point composing of the maximum and minimum value until X/R<3, but shows close agreement with the geometric swirl number after a distance of X/R=3.

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Assessment of Plastic Deformation in Al6061 Alloy using Acoustic Nonlinearity of Laser-Generated Surface Wave (레이저 여기 표면파의 음향비선형성을 이용한 Al6061 합금의 소성변형 평가)

  • Kim, Chung-Seok;Nam, Tae-Hyung;Choi, Sung-Ho;Jhang, Kyung-Young
    • Journal of the Korean Society for Nondestructive Testing
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    • v.32 no.1
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    • pp.20-26
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    • 2012
  • The objective of this study is to assess plastic deformation in aluminium alloy by acoustic nonlinearity of laser-generated surface waves. A line-arrayed laser beam made by high-power pulsed laser and mask slits is utilized to generate the narrowband surface wave and the frequency characteristics of laser-generated surface waves are controlled by varying the slit opening width and slit interval of mask slits. Various degrees of tensile deformation were induced by interrupting the tensile tests so as to obtain aluminum specimens with different degrees of plastic deformation. The experimental results show that the acoustic nonlinear parameter of a laser-generated surface wave increased with the level of tensile deformation and it has a good correlation with the results of micro-Vickers hardness test and electron backscatter diffraction (EBSD) test. Consequently, acoustic nonlinearity of laser-generated surface wave could be potential to characterize plastic deformation of aluminum alloy.

A study on the case of wearing Jungchimak and its form in the Joseon Dynasty (조선시대 중치막(中致莫)의 착용례와 형태 연구)

  • Keum, Jong-Suk
    • The Research Journal of the Costume Culture
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    • v.22 no.5
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    • pp.670-687
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    • 2014
  • This study focused on Jungchimak (coats with side slits) which was typically worn by men in the mid and late Joseon Dynasty. It was done research by examining the case of wearing Jungchimak centering on literature and paintings and analyzing its changes in terms of its form based on the relics that have been found in order to suggest the standard for the evaluation of the period of Jungchimak. Results are as follows. First, men who wore Jungchimak were the king, crown prince and Aristocratic under the official uniform or other robes or as ordinary clothes and shroud. Second, Jungchimak for king was mostly made of Dan (satin damask) and mostly jade green & navy in color, and it commonly used dragon pattern, cloud and treasure pattern, or grape pattern. The fabric used to make Jungchimak for crown prince was Dan & Ju (coarse-finished silk) and puple, green, jade green & navy in color. The fabric used to make Jungchimak for Aristocratic was Ju and indigo or white in color. Third, 251 relics have been announced until now. Most of them were made of silk fabric and had cloud and flower patterns. Fourth, Jungchimak showed changes through time in terms of collar and sleeve shapes, the ratio of armhole to sleeve opening, Geotseop (panel sewn on front opening for overlapping), Dang and Mu (side panel), the ratio of the total length of outer collar to the length of side slits, and the ratio of chest size to the width of lower end.

A Study on Court's Dancing Costume - A Comparison between the Court's Dancing Costume and the People's Clothes - (궁중 무용의상에 관한 연구 - 유럽 일반 복식과의 비교를 중심으로 -)

  • 정옥임;김경희
    • Journal of the Korean Society of Costume
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    • v.52 no.7
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    • pp.123-138
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    • 2002
  • This study as one of a series of systematic studies about dancing costumes will compare the costumes of the 16th. 17th century with their normal style of dress. In brief. this study wants people to know about 16th, 17th century court dancing costumes and to understand the culture in the 16th.17th century. From the comparison between the court's dancing costume and the people's clothes, we could get the conclusion as follows. First, pourpoint. chemis, gown, chausses, etc. that people wore were used for the court's dancing costume. While people Pursued the beauty with the ample silhouette. there were used wrinkles. slits. and tailored oblique line-clothes that gave vitality. Second, silk. linen. brocade. etc. that were used for people's chemises were used for the dancing costume. The good quality and beautiful colors of the dancing costume. however. excelled than of the brilliant court's clothes and the people's clothes. Third. the hair style of dancers were very colorful. For example, there were many kinds of hats and furs, corals, etc. that were attached to them on the most of the long curly hair. In summary, for the court's dancing costume, the same type of clothes was used like the people's clothes. There, however, were differences. The slits, tailored oblique line-clothes and shortened skirt gave the activity. There were many decorations symbolizing the nobles' wealth and Power. Especially the use of the decoration of hair and other stake properties was an effective means for expression. The use of personified masks also contributed to the development of the court dance.

Screening of Endogenous Maize (Zea mays) Substances Enhancing Auxin-induced Inward Curvature in Coleoptilar Slits (안쪽으로 굽어지는 자엽초 박편의 옥신 반응을 촉진하는 옥수수(Zea mays) 내생물질의 탐색)

  • Park, Woong-June
    • Journal of Life Science
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    • v.16 no.5
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    • pp.859-865
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    • 2006
  • When thin slits (e.g., $1mm{\times}10mm$) of maize (Zea mays) coleoptiles were floated on a buffer, they spontaneously curved outward because of unbalanced tissue tension between inner and outer faces. Exogenously applied auxin induced inward curvature of the thin strip of the maize coleoptile in a dose-dependent manner. This bioassay system was used to screen endogenous substances that work together with auxin. In methanol extract of maize coleoptiles including the leaves inside, Active fractions that promote the auxin-induced inward curvature of maize coleoptile slices were found. The curvature-enhancing activity of the extract was not related to energy supply. The active substances were adsorbed to $C_{18}$ cartridges even at pH 10 and eluted in two fractions by 50% and 80% methanol. These substances were named as Curvature-Enhancing Factor-1 (CEF-1) and Curvature-Enhancing Factor-2 (CEF-2), respectively. The CEF-2 was resolved on a reversed phase $C_{18}$ column by HPLC.

A Study on the Adaptive Reuse Techniques through the History of Buildings in the Historic Urban Area - Focused on the Deep and Narrow Lots of Nammun-ro 2Ga, Cheongju - (역사적 도심 내 건축물의 이력을 통해 본 재생기법에 관한 연구 -청주시 남문로 2가동의 세장형 필지를 대상으로-)

  • Kim, Tai-Young
    • Journal of the Korean Institute of Rural Architecture
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    • v.22 no.2
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    • pp.1-8
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    • 2020
  • This study is intended to derive the adaptive reuse techniques through the history and aspects of new construction, extension, repair, and other works, limited to the deep and narrow lots facing Seongan-gil and Nammun-gil in Nammun-ro 2 ga of Cheongju, the historic urban area. The results are as follows. 1) In the case of newly built reinforced concrete buildings, the central part of the top floor of the residence or all floors are opened to the open space(void) to facilitate lighting and ventilation. This is developed as a convection phenomenon due to the temperature difference from the slits between buildings, which affects the entire air flow of the block. 2) The buildings of extension and repair are composed of two-story masonry or steel frame, both the front store facing the road and the house on the back, but it looks like one because it is in contact with each other. If only a small gap between the front and rear buildings is restored to an external space or a space equipped with sun light, a small breath can be provided in lighting and ventilation. 3) The existing two-story wooden stores and houses have lost their external space due to repairs. With minimal intervention to restore the small courtyard, slits, and space under the eaves, it will not only improve lighting and ventilation, but also create a unique appearance as a segment of the elongated store.

Optical Path Analysis for the Optical Encoder using Slit Internal Reflection (슬릿 내부 반사를 이용한 광학식 인코더의 광경로 해석)

  • Kweon, Yong-Min;Kweon, Hyun-Kyu;Park, Chang-Yong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.5
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    • pp.69-77
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    • 2017
  • This paper introduces an optical encoder using the reflection in the slit. The digital optical encoder is a sensor to generate a pulse according to the displacement. An optical encoder is composed of 3 parts: light source, slit plate and light-receiving element. In a conventional encoder, one slit produces one signal. The resolution of the digital optical encoder is determined by the number of slits in the encoder plate. The small slit size is most important among the factors that determine the resolution in a generic-type optical encoder. However, a small slit has low productivity and technical difficulties, so analog optical encoders have emerged as an alternative. Nonetheless, this alternative requires additional circuitry and equipment because of the noise and drafts in the analog signals. A new sensor is presented in this paper with a high resolution and a slit of the same size using the reflection in the slit. Then, the path of the light that passes through the slit ccording to the shape was analyzed, and some paths were expressed in the mathematical expressions. In addition, the optical paths were analyzed in the rectangular, octagonal, and circular encoders, and shown the obtained number of signals per slit by using them. Thus, we confirm that this method has the best performance in circle-shaped slits.

Planar Monopole Antenna with Modified Ground Plane for UWB Communications (UWB 통신을 위한 변형된 접지 면을 갖는 평판형 모노폴 안테나)

  • Kim, Hyun-Chul;Jung, Jin-Woo;Lee, Hyeon-Jin;Lim, Yeong-Seog
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.3
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    • pp.275-281
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    • 2011
  • In this paper, we proposed the small planar monopole antenna with modified ground plane for UWB communications. The proposed antenna not only shows Ultra-Wideband characteristic(3.1~10.6 GHz) suitable for UWB communications but has partially notched-band characteristic to reject 5 GHz WLAN band(5.15~5.35 GHz, 5.470~5.825 GHz). The proposed antenna improved impedance matching through two slits on ground plane, and the rejection band was induced by two ${\lambda}$/4 open stubs on center of two slits. Fabricated antenna satisfied VSWR${\leq}$2 in 2.88~10.83 GHz except for the band rejection of 5.08~5.83 GHz.

An Experimental Study on the Three Dimensional Turbulent Flow Characteristics of Swirl Burner for Gas Furnace (가스난방기용 스월버너의 3차원 난류유동 특성에 관한 실험적 연구)

  • Kim, Jang-Gwon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.2
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    • pp.225-234
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    • 2001
  • This paper represents the vector fields, three dimensional mean velocities, the turbulent intensities, the turbulent kinetic energy, and the Reynolds shear stresses in the X-Y plane of gas swirl burner with a cone type baffle plate measured by using X-probe from hot-wire anemometer system. This experiment is carried out at flow rates 350 and 450ℓ/min respectively, which are equivalent to the combustion air flow rate necessary for heat release 15,000 kcal/hr in gas furnace, in the test section of subsonic wind tunnel. The vector plot shows that the maximum axial mean velocity component exists in the narrow slits situated radially on the edge of gas swirl burner, for that reason, there is some entrainment phenomena of ambient air in the outer region of burner. Moreover, mean velocities in the initial region are largely distributed near the outer region of burner at Y/R≒0.97, but they diffuse and develop into the center flow region of burner according to the increase of axial distance. The turbulent intensities and the turbulent kinetic energy due to large inclination of mean velocity and swirl effect show that the maximum value in the initial region of burner is formed in the narrow slits situated radially on the edge of gas swirl burner and large values are mainly formed in the entire region of burner after X/R=2.4358, hence, the combustion reaction is anticipated to occur actively near this region. And the Reynolds shear stresses are also largely distributed from slite to vanes of gas swirl burner in the intial region, but their values largely disappear after X/R=3.2052.

Types and formative characteristics of the costumes worn by Northeastern Chinese minorities - Focusing on Daur, Ewenki, Oroqen and Hezhen - (중국 동북부 지역 소수민족 복식의 유형과 조형적 특성- 다우르족, 어원커족, 어르첸족, 허저족을 중심으로 -)

  • Seiyoung Park;Dong-Eun Kim;Jiyeon Kim
    • The Research Journal of the Costume Culture
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    • v.31 no.6
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    • pp.776-792
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    • 2023
  • This study aims to analyze the traditional attire of four ethnic minority groups in Northeastern China: Daur, Ewenki, Oroqen, and Hezhen, considering their natural environment, lifestyles, and cultural influences. A literature review of academic papers, books, and online resources was conducted, along with indirect investigations through artifacts. The Daur people, being equestrian, have garments with deep slits, vibrant colors, and elaborate decorations. The Ewenki people wear clothes made of fabric in the summer and primarily deer skin in the winter, and their clothing is simple and not flashy. The Oroqen people's clothing typically has slits at the front, back, or on both sides, and they wear a waist belt. The Hezhen people, an ethnic group that primarily hunts and fishes, wear two-piece clothing with a hip-length top and pants or other fur-trimmed garments. All groups incorporate symbolic patterns influenced by Shamanism, along with animal headgear and leather shoes. We observed that the traditional costumes of ethnic minority groups in Northeastern China share many commonalities in form, but there are detailed differences in material, shape, color, and decoration due to unique geographical and climatic characteristics as well as differences in livelihood. Additionally, the structure of clothing varies depending on each tribe's shamanistic practices and lifestyle.