• Title/Summary/Keyword: Protuberance

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Aerodynamic Heating Characteristics Over a Protuberance in Hypersonic Flows Using Fast Response Thermo Gauges

  • Lee, Hyoung-Jin;Lee, Bok-Jin;Jeung, In-Seuck;Kim, Seoung-Lyoung;Kim, In-Sun
    • International Journal of Aeronautical and Space Sciences
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    • v.11 no.3
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    • pp.193-200
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    • 2010
  • Through experimental investigations utilizing hypersonic shock tunnel-coaxial thermocouples as well as blow down hypersonic wind tunnel-temperature sensitive paints, the heat flux and the temperature over a protuberance were measured and analyzed. The experimental data were subsequently compared to heat flux data that was obtained by using blow down hypersonic wind tunnel and heat flux gauges. According to the comparison, both sets of data illustrated correlation with one another. The measured heat flux was large when the height of the protuberance was large. Experimental results show that heat flux measurements taken at higher locations were greater than those taken at lower locations. For high protuberances, a severe jump in the heat flux was observed, ranging in values within 0.6-0.7 of the height of the protuberances. However, when the protuberance was sufficiently short, a rise in the heat flux was rarely observed as the protuberance was totally submerged under the separation region.

Measurement of Aerodynamic Heating over a Protuberance in Hypersonic Flow of Mach 7 (Mach 7 극초음속 유동 내의 돌출물 공력가열 계측)

  • Lee, Hyoung-Jin;Lee, Bok-Jik;Jeung, In-Seuck;Kim, Seong-Lyong;Kim, In-Sun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.6
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    • pp.562-570
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    • 2009
  • An Experimental study was conducted on the flow characteristics and interference heating caused by a two-dimensional object protruding from a flat plate using a blow-down type of hypersonic wind tunnel. Inflow condition was a free-stream Mach number of 7.0 and a unit Reynolds number of $2.0{\times}10^6/m$. Experimental conditions were varied with three heights of protuberance for two flat plate models which have different lengths. Experimental data were obtained from Schlieren visualization images and heat flux measurements. Also, this paper suggests hypersonic experimental techniques such as boundary-layer detection method in detail. A Large separation region was observed in front of the protuberance and that region was very sensitive to the height of protuberance and the length of the flat plate. For only the highest protuberance, a severe jump of heat flux was observed at the top station among the measuring points. Measured heat flux is large when the height of protuberance is large and the length of flat plate is long.

Aerodynamic Measurement over a Protuberance in Hypersonic Flows Using Coaxial Thermocouple and TSP (동축열전대 및 TSP를 이용한 극초음속 유동 내 돌출물 주위 공력가열 계측)

  • Lee, Hyoung-Jin;Lee, Bok-Jik;Jeung, In-Seuck;Kim, Seong-Lyong;Kim, In-Sun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.10
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    • pp.967-974
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    • 2009
  • Experiments were conducted to measure the heat flux and temperature over a protuberance, using an impulse hypersonic shock tunnel-coaxial thermocouples and a blowdown hypersonic wind tunnel-temperature sensitive paints(TSP). Experimental data were compared with the heat flux data using a blowdown hypersonic wind tunnel-heat flux gauges and it was confirmed data sets agreed well. The measured heat flux is large when the height of the protuberance is large. Also, the heat flux measurements at the upper positions are larger than at the lower positions. For high protuberances, a severe jump in the heat flux is observed, from about 0.6~0.7 of the height of the protuberances. However, when the protuberance is sufficiently short, a rise in the heat flux is rarely observed as the protuberance is submerged totally under the separation region.

Nanoscale Processing on Silicon by Tribochemical Reaction

  • Kim, J.;Miyake, S.;Suzuki, K.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.67-68
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    • 2002
  • The properties and mechanism of silicon protuberance and groove processing by diamond tip sliding using atomic force microscope (AFM) in atmosphere were studied. To control the height of protuberance and the depth of groove, the processed height and depth depended on load and diamond tip radius were evaluated. Nanoprotuberances and grooves were fabricated on a silicon surface by approximately 100-nm-radius diamond tip sliding using an atomic force microscope in atmosphere. To clarify the mechanical and chemical properties of these parts processed, changes in the protuberance and groove profiles due to additional diamond tip sliding and potassium hydroxide (KOH) solution etching were evaluated. Processed protuberances were negligibly removed, and processed grooves were easily removed by additional diamond tip sliding. The KOH solution selectively etched the unprocessed silicon area. while the protuberances, grooves and flat surfaces processed by diamond tip sliding were negligibly etched. Three-dimensional nanofabrication is performed in this study by utilizing these mechanic-chemically processed parts as protective etching mask for KOH solution etching.

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Nanodeformation Behaviors of the Single Crystal Silicon and the Pyrex glass 7740 during Nanoscratch (나노스크래치 공정에서 단결정 실리론 및 파이렉스 7740 의 나노변형거동)

  • 신용래;윤성원;강충길
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.10a
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    • pp.363-366
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    • 2003
  • In nanomachining processes, chemical effects are more dominant factor compared with physical deformation. For example, during the nanoscratch on a silicon surface in the atmosphere, micro protuberances are formed due to the mechanochemical reaction between the diamond tip and the surface. On the contrary, in case of chemically stable materials, such as ceramics or glasse, the surface protuberance are not formed. The purpose of this study is to understand effects of the mechanochemical reaction between tip and surfaces on deformation behaviors of hard-brittle materials. Nanometerscale elasoplastic deformation behavior of single crystal silicon (100) was characterized with the surface protuberance phenomena, and compared with that of borosilicate (Pyrex glass 7740).

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Experimental Study of Waterproofing Sheet using coat Material filling into the Protuberance to Improve the Durability for Concrete Structure (콘크리트 구조물의 내구성 증진을 위한 돌기입체형 방수시트를 이용한 충전형 옥상복합 방수재료의 실험적 연구)

  • Kim, Jin-Seong;Park, Jin-Sang;Jung, Chun-Su;Oh, Sang-Keun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.649-652
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    • 2006
  • The exist waterproofing membrane cause not to assure proper thickness in constructing. It become a serious problem which as decreasing of durability, waterproofing membrane to be tom and break down. Therefore, it is necessary that the expert have to construct waterproof works,, if not, it can be frost and thawing or chemical corrosion called one of the reason in maintaining the safety of concrete structure. In summarize, for this paper, it would be understand that exposed and compound experimental study of waterproofing sheet using coat material filling into the protuberance to improve the durability for concrete structure can widely apply to field to solve the these significant problem.

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A Study on the Nano-Deformation Behaviors of Single Crystal Silicon and Amorphous Borosilicate Considering the Mechanochemical Reaction (기계화학적 반응을 고려한 단결정 실리콘과 비정질 보로실리케이트의 나노 변형 거동에 관한 연구)

  • 윤성원;신용래;강충길
    • Transactions of Materials Processing
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    • v.12 no.7
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    • pp.623-630
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    • 2003
  • Nanomachining process, static nanoplowing, is one of the most promising lithographic technologies in terms of the low cost of operation and variety of workable materials. In nanomachining process, chemical effects are more dominant factor compared with those by physical deformation or fracture. For example, during the nanoscratch on a silicon surface in the atmosphere, micro protuberances are formed due to the mechanochemical reaction between diamond tip and the surfaces. On the contrary, in case of chemically stable materials, such as ceramic or glass, surface protuberances are not formed. The purpose of this study is to understand effects of the mechanochemical reaction between tip and surfaces on deformation behaviors of hard-brittle materials. Nanometerscale elasoplastic deformation behavior of single crystal silicon (100) was characterized with micro protuberance phenomena, and compared with that of borosilicate (Pyrex glass 7740). In addition, effects of the silicon protuberances on nanoscratch test results were discussed.

Miniscalpel acupuncture points of the cervical region: A review

  • Kim, Ju-ran;Lee, Jung Hee;Gong, Han Mi;Jun, Seungah;Chung, Yeon-Joong;Park, Chung A;Choi, Seong Hun;Lee, Geon-Mok;Lee, Hyun-Jong;Kim, Jae Soo
    • Journal of Acupuncture Research
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    • v.34 no.3
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    • pp.91-100
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    • 2017
  • Objectives : We conducted a literature search to identify trends with respect to miniscalpel acupuncture points (MAPs) of the cervical region with the aim of providing guidance regarding miniscalpel acupuncture (MA) in the cervical region. Methods : We searched 2 overseas sites (PubMed and Google Scholar) and 5 domestic sites (NDSL, RISS, KISS, OASIS and Korean Traditional Knowledge Portal) for clinical trials of MA of the cervical region. The search terms used were "acupotomy or miniscalpel acupuncture or miniscalpel" and "cervical." Of 73 studies found, 11 were included in this review, 6 of which presented exact MAPs. Owing to the lack of data, we refer to 1 Korean and 4 Chinese articles to analyze the exact location and meaning of the MAPs used in the published studies and to propose other clinically applicable MAPs. Results : We identified 10 of the most commonly used MAPs in the published studies, including those located below the external occipital protuberance, 2-2.5 cm both side down of the external occipital protuberance, 4.5-5 cm both side down of the external occipital protuberance and C3-7 spinous process. Furthermore, we proposed 13 additional MAPs that can be used clinically. Conclusion : We hope that this study will form a basis for the development of MA and hope to improve the safety and reproducibility in future MA studies of the cervical region.

DIFFERENTIAL DIAGNOSIS OF CLASS III PROFILE (III급 부정교합자의 연조직 측모 감별에 관한 연구)

  • Hwang, Byung-Nam;Rhee, Seung-Hoon;Lee, Jeong-Keun;Lee, Jai-Bong
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.22 no.2
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    • pp.174-183
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    • 2000
  • This study was performed to investigate the characteristics of soft tissue profile of the class III malocclusion and to test the yardstick far differential diagnosis between surgical and orthodontic patients. Initial lateral cephalograms of orthodontic group(30 patients) that have acceptable occlusion and profile by orthodontic treatment alone and surgical group(30 patients) that have favorable occlusion and profile by combined surgical-orthodontic treatment were selected in Ajou university hospital. Powell and Burstone II analysis were made on the tracing. Descriptive, comparative, factor, cluster, and discriminant analysis were carried out with computer program. The results were as followings : 1. Patients who received surgery had a more concave profile and a longer lower facial height than patients who received orthodontic treatment alone. 2. Nasolabial angle, ratio of vertical height, and mentolabial sulcus were significantly different at the 5% level. And facial protuberance, upper lip protuberance, mentocervical angle, nasofrontal angle, nasomental angle, mandibular vertical height, angle between cervix and lower face, ratio of mandibular vertical height divided by cervical depth, ratio of vertical height between upper and lower lip, and maxillary protuberance were significantly different at the 1% level. 3. 8 factors were extracted and factor 2, 3, and 8 showed significant differences by factor analysis. 4. Orthodontic group (25) and surgical group (35) were classified by cluster analysis. 5. Discriminant function was D = 0.079Nasomental angle + 0.081Sn-Gn + 3.343Sn-Gn/C-Gn + 1.734Sn-St/St-Me' -26.460, and cutting score was 0, so we can discriminate that orthodontic group has the score above 0, and surgery group below 0. And 91.7% of original grouped cases were correctly classified.

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Aerodynamic acoustics of automotive weather strip protuberance (풍절소음 저감을 위한 웨더스트립 돌출부 형상연구)

  • Kim, Tae-Hoo;Lee, Gye-Ho;Jeon, Seung-Gyeong;Hwang, Jung-Ho;Kim, Joon-Hyung
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2546-2551
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    • 2007
  • Weather Strip(W/S) is a rubber part to proof water, sound and dust for opening and shutting devices including vehicle doors. And it requires high dimension precision and durability to proof water, noise, vibration and etc. But ironically it itself makes some wind noise because of some protuberance with glasses. The air flow analysis of door part of vehicle makes it possible to calculate and find out the cause of wind noise. In previous analysis, we focus on the numerical air flow analysis of the automobile side part. We do 2D-C.F.D first and 3D second. Through simulations, we can calculate the amount of sound pressure level at the glass run and find out the effects of glass run to make wind noise. Finally we can improve shape of glass run to reduce wind noise although it is small amounts of sound pressure reduction compared with total vehicle noise level.

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