• 제목/요약/키워드: T/B ratio

검색결과 991건 처리시간 0.027초

각형강관 T형 접합부의 면내 휨모멘트 평가 (Evaluation on the In-plane Bending Moment for T-joints with Square Hollow Structural Sections)

  • 박금성;이상섭;최영환;배규웅
    • 한국강구조학회 논문집
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    • 제21권5호
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    • pp.451-459
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    • 2009
  • 본 논문은 냉간성형 각형강관 T형 접합부의 면내 휨모멘트를 평가하는데 목적이 있다. 이전 연구로부터, 주관 폭에 대한 지관 폭의 비가 0.71이하인 T형 접합부는 뚜렷한 최대 휨강도를 나타내지 못하는 접합부의 파괴모드는 주관 플랜지의 휨파괴이다. Zhao에 의해 수행된 실험을 포함한 결과로부터 주관 폭두께비는 ${16.7{\leq}2{\gamma}(=B/T){\leq}33}$이고, 주관 폭에 대한 지관 폭의 비인 폭비는 ${0.34{\leq}{\beta}(=b_{1}/B){\leq}0.71}$의 범위인 냉간성형 각형강관 T형 접합부에 대한 최대 휨강도 정의를 위한 변형제한치는 주관폭(B)의 1% 변형이며, 최대 휨강도는 1.5M1%B로 정의할 수 있다. 기본형에 대한 항복선 모델과 기존 연구자들에 의해 수정 제안된 항복선 모델식을 검토하여 실험결과와 비교한 결과, Zhao의 제안식이 가장 좋은 대응도와 분포도를 보였다. 따라서, 각형강관 T형 접합부에 대한 면내 설계 휨강도식으로 Zhao가 수정 제안한 항복선 모델식을 적용하는 것이 가장 합리적인 것으로 생각된다.

제주도 자망이망율에 관하여 -고등어 자망의 이망율 비교- (ON THE CATCH OF GILL NET IN THE JEJU ISLAND -Comparison of mackerel catch in monofilament and multifilament gill nets-)

  • 손태준
    • 한국수산과학회지
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    • 제8권1호
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    • pp.7-10
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    • 1975
  • 제주도 고등어 자망어업의 주어기인 1974년 5월 28일부터 8월 31일까지 서귀포와 비양도근해어장에서 고등어 자망어구의 이망율에 관한 시험조업결과는 다음과 같다. 1. $X^2$ t 검정에 의하면 고등어 nylon-monofilament 자망 B형이 nylon-multifilament 자망 A형보다 이망성능이 우위하고 나망율비는 $m_A:m_B=1:1.8$이다. 2. 망목 75mm인 nylon-monofilament 자망 C형, D형이 망목 85mm인 nylon-monofilament 자망 E형 F형 보다 이망성능이 우위하고 이망율비는 $m_E{\cdot}F:m_C{\cdot}D=1:2.8$이다. 3. 망계 굵기가 120tex와 75tex이고 망목이 75m 및 85mm인 C, D, E, F, 형에서는 상호간의 우위는 모두 확인할 수 없었다.

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X선 반가폭을 이용한 Al 2024-T3 합금의 피로수명예측에 관한 연구 (A Study on the Prediction of Fatigue Life in 2024-T3 Aluminium using X-ray Half-Value Breadth)

  • 조석수;김순호;주원식
    • 한국정밀공학회지
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    • 제17권1호
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    • pp.145-152
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    • 2000
  • X-ray diffraction method detects change of crystal lattice distance under material surface using diffraction angle 2$\theta$. This technique can be applied to the behavior on slip band and micro crack due to material degradation. The relation between half-value breadth and number of cycle has three stages which constitute rapid decrease in initial number of cycles, slight decrease in middle number of cycles and rapid decrease in final number of cycles. The ratio of half-value breadth takes a constant value on B/B$_{0}$-N diagram with loading condition except early part of fatigue life. The ratio of half-value breadth B/B$_{0}$ with respect to number of cycle to failure N$_{f}$ has linear behavior on B/B$_{0}$-log N$_{f}$ diagram. Therefore, in this paper the estimation of fatigue life by average gradient method has much less estimated mean error than the estimation of fatigue life by log B/B$_{0}$-log N/N$_{f}$ relation.elation.ation.

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점토 광물 조성이 점토기반 분리막의 곡강도에 미치는 영향 (Effect of Clay-Mineral Composition on Flexural Strength of Clay-based Membranes)

  • 이영일;엄정혜;김영욱;송인혁
    • 한국세라믹학회지
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    • 제51권5호
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    • pp.380-385
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    • 2014
  • Clay-based membranes with submicron pore size were successfully prepared by a simple pressing process using low-cost starting materials(e.g., kaolin (K), bentonite (B), talc (T), and sodium borate). The green bodies were sintered at $1000^{\circ}C$ for 2 h in air. The effect of clay-mineral composition on the flexural strength of clay-based membranes was investigated. The porosity of the clay-based membranes could be controlled within the range of 34 - 42% by adjusting the starting composition. The flexural strength of the low-cost membranes depended on both the porosity and the ${\alpha}$-quartz content. In turn, the porosity and ${\alpha}$-quartz content were affected by the (B+T) /(K+B+T) ratio. The plot of strength relative to this ratio, showed a maximum when the ratio was 0.4. The typical flexural strength of these clay-based membranes (with ratio 0.4) was 28 MPa at 34% porosity.

원심주조된 내열강의 미세조직 및 기계적성질에 미치는 단조 조건의 영향 (Effect of Forging Condition on the Microstructure and Mechanical Properties in Centrifugal Casted Heat Resistant Steel)

  • 강창룡;이상명;조덕호;박영태;이도훈;김영철
    • 동력기계공학회지
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    • 제13권3호
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    • pp.47-52
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    • 2009
  • The effect of forging start temperature, forging ratio on the microstructure and mechanical properties of B7B4 steel ware investigated. Microstructure of centrifugal casted B7B4 steel consisted of martensite and ferrite phase. The volume fraction of ferrite increased with increase of forging start temperature and decreased with increase of forging ratio. Tensile strength and hardness decreased with higher of forging start temperature, while impact value and elongation increased with higher of forging start temperature. With increase of forging ratio, tensile strength rapidly increased up to the forging ratio of 30%, and then slowly increased, but elongation was decreased. Hardness and impact value rapidly increased with increase of forging ratio.

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보비탕(補脾湯)이 methotrexate로 유발(誘發)된 흰쥐의 면역기능저하(免疫機能低下)에 미치는 영향(影響) (Effect of Bobitang water extracts on immunosuppression induced by Methotrexate in SD rats)

  • 조현희;윤혜진;서정민;백정한
    • 대한한방소아과학회지
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    • 제21권1호
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    • pp.227-252
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    • 2007
  • Objectives : In order to investigate the effect of Bobitang on SD rats with deteriorated immunity caused by methotrexate. Methods : The test sample were dosed once a day for 14 days by gastric gavage at a dosage 1,000, 500 and $250mg/kg/10m{\ell}$ from 2 days after last MTX-dosing, and the changes on body weight and gains, spleen weight and total blood leukocyte numbers, total lymphocyte numbers, the percentage of B-cell, T-cell, CD3+CD4+ T-cell, CD3+CD8+ T-cell and CD4+/CD8+ T-cell ratios in the blood and spleen were observed. Results : The changes on body weight gains, the spleen weight, the total blood leukocyte numbers, the total lymphocyte numbers in the blood and spleen, the ratio of T-cell in the blood and spleen, the ratio of CD3+CD4+ T-cell in the blood and spleen were increased significantly in BBT Extracts groups as compared with control group. The ratio of B-cell in the blood and spleen was not increased significantly in BBT Extracts groups as compared with control group. The percentage of CD3+CD8+ T-cell in the blood and spleen was decreased significantly in BBT Extracts groups as compared with control group. The ratio of CD4+/CD8+ T-cell in blood and spleen was increased significantly in BBT Extracts group as compared with control group. Conclusions : According to the above results, Bobi-Tang has an effect of increasing immune responses on SD rats with deteriorated immunity caused by methotrexate.

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Identifying torsional eccentricity in buildings without performing detailed structural analysis

  • Tamizharasi, G.;Murty, C.V.R.
    • Earthquakes and Structures
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    • 제23권3호
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    • pp.283-295
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    • 2022
  • Seismic design codes permit the use of Equivalent Static Analysis of buildings considering torsional eccentricity e with dynamic amplification factors on structural eccentricity and some accidental eccentricity. Estimation of e in buildings is not addressed in codes. This paper presents a simple approximate method to estimate e in RC Moment Frame and RC Structural Wall buildings, which required no detailed structural analysis. The method is validated by 3D analysis (using commercial structural analysis software) of a spectrum of building. Results show that dynamic amplification factor should be applied on torsional eccentricity when performing Response Spectrum Analysis also. Also, irregular or mixed modes of oscillation arise in torsionally unsymmetrical buildings owing to poor geometric distribution of mass and stiffness in plan, which is captured by the mass participation ratio. These irregular modes can be avoided in buildings of any plan geometry by limiting the two critical parameters (normalised torsional eccentricity e/B and Natural Period Ratio 𝜏 =T𝜃/T, where B is building lateral dimension, T𝜃 uncoupled torsional natural period and T uncoupled translational natural period). Suggestions are made for new building code provisions.

Association between dietary flavanones intake and lipid profiles according to the presence of metabolic syndrome in Korean women with type 2 diabetes mellitus

  • Oh, Ji Soo;Kim, Hyesook;Vijayakumar, Aswathy;Kwon, Oran;Choi, Young Ju;Huh, Kap Bum;Chang, Namsoo
    • Nutrition Research and Practice
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    • 제10권1호
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    • pp.67-73
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    • 2016
  • BACKGROUND/OBJECTIVES: This study was aimed at examining the association between dietary flavanones intake and lipid profiles according to the presence of metabolic syndrome (MetS) in Korean women with type 2 diabetes mellitus (T2DM). SUBJECTS/METHODS: A cross-sectional analysis was performed among 502 female T2DM patients (non-MetS group; n = 129, MetS group; n = 373) who were recruited from the Huh's Diabetes Clinic in Seoul, Korea between 2005 and 2011. The dietary intake was assessed by a validated semi-quantitative food frequency questionnaire (FFQ) and the data was analyzed using the Computer Aided Nutritional Analysis program (CAN-Pro) version 4.0 software. The intake of flavanones was estimated on the basis of the flavonoid database. RESULTS: In the multiple linear regression analysis after adjustment for confounding factors, daily flavanones intake was negatively associated with CVD risk factors such as total cholesterol, LDL-cholesterol, and apoB and apoB/apoA1 ratio only in the MetS group but not in the non-MetS group. Multiple logistic regression analysis revealed that the odds ratio for a higher apoB/apoA1 ratio above the median (${\geq}0.74$) was significantly low in the $4^{th}$ quartile compared to that in the $1^{st}$ quartile of dietary flavanones intake [OR: 0.477, 95% CI: 0.255-0.894, P for trend = 0.0377] in the MetS group. CONCLUSIONS: Dietary flavanones intake was inversely associated with the apoB/apoA1 ratio, suggesting a potential protective effect of flavanones against CVD in T2DM women with MetS.

단열 및 등온수평 경계조건을 갖는 직각 밀폐용기내 공기의 자연대류 열전달 (Natural Convection Heat Transfer in Rectangular Air Enclosures With Adiabatic and Isothermal Horizontal Boundary Conditions)

  • 이진호;김무현;모정하
    • 대한기계학회논문집
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    • 제14권1호
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    • pp.207-213
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    • 1990
  • 본 연구에서는 종횡비(aspect ratio` A=H/L)가 1 이하인 직각밀폐용기내 수평 경계면이 자연대류열전달에 미치는 영향을 조사하기 위해 단열조건인 경우와 등온조건 인 경우 { $T_{H}$.simeq. $T_{T}$$T_{C}$.simeq. $T_{B}$, 따라서 온도차의 비, .DELTA. $T_{V/}$ .DELTA. $T_{H}$=( $T_{T}$- $T_{B}$)/( $T_{H}$- $T_{C}$).simeq.1} Mach-Zehnder간섭계 및 수치해석 을 통해 온도장 및 각 면에서의 열전달특성의 차이를 자세히 구명하였다. 특히 등온 수평면조건인 경우 상부수평면온도가 하부수평면온도보다 높을 때 ( $T_{T}$$T_{B}$) 직각용기내는 수직방향으로 안정된 온도구배가 형성되어, 양단온도차(.DELTA. $T_{H}$= $T_{H}$- $T_{C}$)에 의해 기본적으로 존재하는 자연대류흐름을 억제하게 된다. 이때 자연대류흐름의 억제정도를 나타내는 주요 물리적 변수로서 온도차의 비, .DELTA. $T_{V/}$ .DELTA. $T_{H}$가 있다. 이러한 물리적 현상은, 기본적으로 존재하는 유체내 자연대류효 과를 억제함으로써 중력장하에서 양질의 결정을 얻고자 하는 결정성장(growth of cry- stal)등에 관계된다. 본 연구는 실험유체가 공기이고 .DELTA. $T_{V/}$.DELTA. $T_{H}$=1인 경우 를 택하여 일반적인 단열조건의 경우와 열전달특성의 차이를 비교한 것이다.전달특성의 차이를 비교한 것이다.다.전달특성의 차이를 비교한 것이다.

PHOTOMETRIC PROPERTIES OF THE BRIGHT LENTICULAR GALAXY NGC 5102

  • Sohn, Young-Jong;Chun, Mun-Suk;Byun, Yong-Ik
    • 천문학회지
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    • 제24권2호
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    • pp.151-159
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    • 1991
  • Using the photographic imagery of the SO galaxy NGC 5102, the equivalent luminosity profile and the fractional integrated luminosity curve have been derived. Several photometric parameters of the galaxy, such as a total magnitude ($B_T$), equivalent radius ($r^*_e$), effective surface brightness (${\mu}^*_e$), and concentration indices ($C_{21}$, $C_{32}$) were derived from the luminosity profiles. According to the decomposition method from the nonlinear least squares fitting, photometric parameters of the bulge (${\mu}_e$, $r_e$) and the exponential disk (${\mu}(0)$, ${\alpha}^{-1}$), and the bulge to total luminosity ratio (B/T) were obtained. The derived central disk surface brightness (${\mu} (0)\;=\;22.06\;{\pm}\;0.18\;mag/\Box"$) and the evaluated B/T ratio (= 0.52) of the NGC 5102 are close to the mean values (${\mu} (0)\;=\;21.65\;{\pm}\;0.3\;mag/\Box"$, B/T=0.63) of the SO galaxies. Analysis showed that a lens-like hump is embedded in the equivalent luminosity profile of the NGC 5102.

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