• 소성∙가공
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• 제25권4호
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• pp.235-241
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• 2016

Dimensional accuracy of hot coil is improved by precise control of thickness profiles, flatness, width and winding profile. Especially, precise width control is important because yield could be increased significantly. Precise width control can be improved by predicting the amount of width spread. The purpose of this study is to develop the advanced prediction model for width spread in hot finish rolling for controlling width precisely. FE-simulations were performed to investigate the effect of process variables on width spread such as reduction ratio, forward and backward tension and initial width at each stand. From the statistical analysis of simulated data, advanced model was developed based on the existing models for strip width spread. The experimental hot rolling trials showed that newly developed model provided fairly accurate predictions on the strip width spread during the whole hot finishing rolling process.

• 한국강구조학회 논문집
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• 제16권6호통권73호
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• pp.769-780
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• 2004

본 논문의 목적은 인장용 연결 플레이트를 갖는 냉간성형 각형강관 갭 N형 접합부의 실험연구를 통하여 접합부 거동을 평가하는데 있다. 실험을 위한 주요 변수로는 주관의 폭두께비, 주관에 대한 지관의 폭의 비, 편심비, 압축지관 형상, 지관의 각도, 주관 상부 플랜지면 보강 등이 있다. 이와 같은 변수들로 구성된 갭 N형 접합부에 대한 내력 및 파괴모드 등에 대하여 실험을 통해 고찰하고자 한다. 실험결과, 갭 N형 접합부는 폭비에 관계없이 접합부의 인장측 변위가 선행하여 접합부의 내력이 결정되었으며, 접합부 파괴는 접합된 주관면의 찢어짐 파괴모드로 결정되었다. 인장 및 압축측 폭비(${\beta}$)가 클수록 주관 폭두께비가 작을수록 접합부의 항복하중 및 최대하중은 선형으로 상승하는 것으로 나타났다. 주관의 폭두께비($2{\gamma}$)가 작을수록 접합부의 내력비교 곡선은 급격히 상승함을 알 수 있다. 인장용 연결 플레이트를 갖는 갭 N형 접합부에 대하여 변수에 따른 접합부의 하중, 초기강성, 연성능력 및 파괴모드 변화 등에 대한 결과에 대해서도 정리하여 나타내었다.

• 한국강구조학회 논문집
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• 제19권6호
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• pp.725-735
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• 2007

이 연구에서는 두께가 얇은 강판을 가진 철골-콘크리트 합성기둥에서 강판의 국부 좌굴 강도 및 국부 좌굴 후 강도에 대한 해석적인 연구를 수행하였다. 콘크리트 충전에 의하여 합성기둥에서 판의 국부 좌굴 성능이 향상되는 것을 경계 조건을 조정하여 해석에 반영하였고, 탄성 좌굴 해석을 통해 한계 폭-두께비를 제안하였다. 또한 초기 처짐 및 잔류 응력을 해석에 반영하여, 다양한 폭-두께비에 해당하는 평판의 비선형 유한 요소 해석을 통해 초기 국부 좌굴 강도 및 좌굴 후 강도를 산정하였다. 이러한 비선형 해석 결과를 이용하여 판의 유효 폭을 산정하였고, 유효 폭을 이용한 철골-콘크리트 합성기둥의 최대 압축 내력식을 제안하였다. 제안식에 의한 계산된 값과 기존의 실험결과를 비교함으로서 제안식의 타당성을 검증하였다.

• 한국강구조학회 논문집
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• 제23권2호
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• pp.229-236
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• 2011

본 연구는 폭두께비(W/T)에 따른 중심압축하중을 받는 SC(Steel Plate-Concrete)구조의 압축거동 특성을 파악하는 것이 주목적이다. SC구조는 전단 연결재를 갖는 샌드위치 강판 사이에 콘크리트를 타설하여 시공하는 구조이다. SC구조의 실험체는 폭두께비(W/T)가 1.60와 3.56인 실험체로 구분하였다. 실험을 통하여 다음과 같은 결과를 얻었다. SC구조 실험체의 파괴양상은 최대압축강도에 도달하기 전에 스터드와 스터드 사이 강판이 국부좌굴하고 콘크리트는 일부 균열 및 박리현상이 나타났다. 또한 SC구조 실험체의 최대압축강도는 기존 설계기준식(AISC 2005, ACI318-05 및 KBC 2005)에 의한 압축강도보다 거의 크게 나타났다. SC구조 실험체의 폭두께비(W/T)가 증가할수록 강판에 의한 SC구조 실험체의 콘크리트 구속효과는 감소하는 것으로 나타났다.

• Geomechanics and Engineering
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• 제2권1호
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• pp.29-44
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• 2010

Vertical vibration tests were conducted using model footings of different size and mass resting on the surface of finite sand layer with different height to width ratios which was underlain by either rigid concrete base, under both dry and saturated condition. The effect of saturation on the damping ratio of finite sand stratum underlain by a rigid base has been verified and compared with the results obtained for the case of finite dry sand stratum underlain by the rigid base. Comparison of results of the experimental study showed that the damping in both the cases is less than 10%. The damping ratio obtained for finite saturated sand stratum is marginally lower than that obtained on finite dry sand stratum at H/B ratio of 0.5. The difference between the two cases becomes significant when the H/B ratio increases to 3.0, indicating the significant influence of soil moisture on damping ratio of foundation- soil system with increase in the thickness of the finite sand stratum. Comparison of the predicted damping ratio for a homogeneous sand stratum with the experimental damping ratio obtained corresponding to the height to width ratio of 3.0 of the finite sand stratum underlain by the rigid concrete base indicates a significant reduction in damping ratio of the foundation-soil system for both the cases.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1998년도 유체기계 연구개발 발표회 논문집
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• pp.135-141
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• 1998

Some sized centrifugal compressor were designed and their performance measured to investigate the effects of exit blade thickness, width and back swept angle. The impeller of larger blade thickness shows low pressure ratio compared with that of smaller one. Backswept angle have also large effect on the efficiency. Measured values of slip factor are quite different from the estimated values of Wiesner-Busemann model and increase with the flow rate.

• 한국유체기계학회 논문집
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• 제2권1호
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• pp.15-21
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• 1999

Some sized centrifugal compressors were designed and their performance measured to investigate the effects of exit blade thickness, width and back swept angle. The impeller of larger blade thickness shows low pressure ratio compared with that of smaller ones. Backswept angle also have a large effect on the efficiency. Measured values of slip factor are quite different from the estimated values of the Wiesner-Busemann model and an increase in the flow late.

• 한국정밀공학회지
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• 제14권5호
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• pp.150-156
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• 1997

Three dimensional finite element analysis was conducted to estimate the effect of shape parameters (plate width and thickness) on the stress intensity factor for crack in the integrally stiffened plate. Analysis was done for width ratios of 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, and thickness ratios of 2, 3, 4, 6. Based on these results, an empirical equation of geometry factor is formulated as a function of crack length and thickness ratio.

• Journal of Periodontal and Implant Science
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• 제51권2호
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• pp.88-99
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• 2021

Purpose: Direct intraoral scanning and superimposing methods have recently been applied to measure the dimensions of periodontal tissues. The aim of this study was to analyze various correlations between labial gingival thickness and underlying alveolar bone thickness, as well as clinical parameters among 3 tooth types (central incisors, lateral incisors, and canines) using a digital method. Methods: In 20 periodontally healthy subjects, cone-beam computed tomography images and intraoral scanned files were obtained. Measurements of labial alveolar bone and gingival thickness at the central incisors, lateral incisors, and canines were performed at points 0-5 mm from the alveolar crest on the superimposed images. Clinical parameters including the crown width/crown length ratio, keratinized gingival width, gingival scallop, and transparency of the periodontal probe through the gingival sulcus were examined. Results: Gingival thickness at the alveolar crest level was positively correlated with the thickness of the alveolar bone plate (P<0.05). The central incisors revealed a strong correlation between labial alveolar bone thickness at 1 and 2 mm, respectively, inferior to the alveolar crest and the thickness of the gingiva at the alveolar crest line (G0), whereas G0 and labial bone thickness at every level were positively correlated in the lateral incisors and canines. No significant correlations were found between clinical parameters and hard or soft tissue thickness. Conclusions: Gingival thickness at the alveolar crest level revealed a positive correlation with labial alveolar bone thickness, although this correlation at identical depth levels was not significant. Gingival thickness, at or under the alveolar crest level, was not associated with the clinical parameters of the gingival features, such as the crown form, gingival scallop, or keratinized gingival width.

• 한국안전학회지
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• 제13권3호
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• pp.24-31
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• 1998

Variable thickness plates are commonly encountered in the majority of mechanical/structural components of industrial applications. And, as a result of the unsymmetry of the structure or the load and the anisoptropy of the materials, the cracks in engineering structures are generally subjected to combined stresses. In spite of considerable practical interest, however, a few fracture mechanics study on combined mode crack in a variable thickness plate have carried out. In this respect, combined mode I/III stress intensity factors $K_I$ and $K_III$ at the crack tip for a variable thickness plate were obtained by 3-dimensional finite element analysis. Variable thickness plates containing a central slant crack were chosen. The parameters used in this study were dimensionless crack length $\lamda$, crack slant angle $\alpha$, thickness ratio $\beta$ and width ratio $\omega$. Stress intensity factors were calculated by crack opening displacement(COD) and crack tearing displacement(CTD) method.