• Steel and Composite Structures
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• 제49권1호
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• pp.109-123
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• 2023

Headed studs welded to steel beams and embedded within the concrete of deck slabs are vital components of modern composite floor systems, where safety and economy depend on the accurate predictions of the stud shear resistance. The multitude of existing deck profiles and the complex behavior of studs in deck slab ribs makes developing accurate and reliable mechanical or empirical design models challenging. The paper addresses this issue by presenting a machine learning (ML) model developed from the natural gradient boosting (NGBoost) algorithm capable of producing probabilistic predictions and a database of 464 push-out tests, which is considerably larger than the databases used for developing existing design models. The proposed model outperforms models based on other ML algorithms and existing descriptive equations, including those in EC4 and AISC 360, while offering probabilistic predictions unavailable from other models and producing higher shear resistances for many cases. The present study also showed that the stud shear resistance is insensitive to the concrete elastic modulus, stud welding type, location of slab reinforcement, and other parameters considered important by existing models. The NGBoost model was interpreted by evaluating the feature importance and dependence determined with the SHapley Additive exPlanations (SHAP) method. The model was calibrated via reliability analyses in accordance with the Eurocodes to ensure that its predictions meet the required reliability level and facilitate its use in design. An interactive open-source web application was created and deployed to the cloud to allow for convenient and rapid stud shear resistance predictions with the developed model.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.227-228
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• 2023

A floating floor generally consists of mortar bed separated from the structural RC slab by a continuous resilient layer. It is known that the floating floors are a type of vibration-isolation system to improve the impact sound insulation performance. However, some researchers have demonstrated that the amplification of vibration response at a specific range of frequencies results in an increase in the impact sound level. This study carried out the forced vibration tests to obtain the frequency response function (FRF) of a floating floor compared with a bare RC slab. Test results shows that the additional peak occur in vibrational spectrum of the floating floor except natural vibration modes of the bare RC slab. This is because the relatively flexible resilient material and mass of the mortar bed offer an additional degree of freedom in the structural system. Therefore, it could be efficient for reduction of floor impact vibration and noise to control the additional mode frequency and response of floating floors.

• 천문학회보
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• 제41권2호
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• pp.57.3-58
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• 2016

A symbiotic star is a wide binary system consisting of a hot white dwarf and a mass losing giant, where the giant loses its material in the form of a slow stellar wind resulting in accretion onto the white dwarf through gravitational capture. Symbiotic stars are known to exhibit unique spectral features at 6825 and 7082, which are formed from O VI 1032 and 1038 through Raman scattering with atomic hydrogen. In this Monte Carlo study we investigate the flux ratio of 6825 and 7082 in a neutral region with a geometric shape of a slab, cylinder and sphere. By varying the amount of neutral hydrogen parametrized by the column density along a specified direction, we compute and compare the flux ratio of Raman scattered O VI 6825 and 7082. In the column density around 1020 cm-2, flux ratio changes in a complicated way, rapidly decreasing from the optically thin limit to unity the optically thick limit as the column density increases. It is also notable that when the neutral region is of a slab shape with the O VI source outside the slab, the optically thick limit is less than unity, implying a significant fraction of O VI photons escape through Rayleigh scattering near the boundary. We compare our high resolution CFHT data of HM Sge and AG Dra with the data simulated with finite cylinder models confirming that 'S' type symbiotic tend to be characterized by thicker HI region that 'D' type counterparts. It is expected that this study will be useful in interpretation of the clear disparity of Raman O VI 6825 and 7082 profiles, which will shed much light on the kinematics and the asymmetric distribution of O VI material around the hot white dwarf.

• 한국구조물진단유지관리공학회 논문집
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• 제12권5호
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• pp.74-80
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• 2008

본 논문은 기둥형상비를 실험 변수로 가지는 무량판 슬래브-기둥 접합부의 내진성능을 평가하는데 있다. 본 연구에서는 무량판 슬래브의 뚫림 전단파괴를 방지하기 위하여 본 연구와 병행하여 진행된 연구에서 개발된 연속 절곡된 전단보강근을 적용하였다. 기둥형상비에 따른 실험체는 각각 FIS1-05(0.5), FIS1- 10(1.0), FIS1-20(2.0) 이다. 실험체의 수평방향으로 정적 수평하중을 가력 하였으며, 중력하중비에 의한 일정 수직 하중을 적용하였다. 실험결과는 슬래브-기둥 접합부의 수평 변위 및 강도를 기준으로 평가하였다. 분석결과, FIS1-05, FIS1-20와 같은 장방형 기둥을 갖는 접합부의 성능이 FIS1-10와 같은 정방형 기둥을 갖는 접합부보다 우수한 것으로 평가되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제12권2호
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• pp.139-148
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• 2008

기 시행된 관련 보고서에 의하면 외관 상태에 대한 육안 점검은 구조적 안전성 평가를 위해 대단히 중요한 부분이다. 본 연구는 개별 손상유형의 분리 평가에 의한 콘크리트 바닥판에 대하여 개선된 상태평가 방법을 제안한다. 먼저, 한데 묶여서 다루어졌던 여러 유형의 손상들을 분리하고, 다음으로 현행 지침을 토대로 가중점수를 부여하였다. 그 밖의 전반적인 과정은 혼란을 피하기 위하여 가능한 한 그대로 유지하였다. 제안된 방법을 4개의 교량에 대해 기 수행된 진단프로젝트에 적용, 시험 결과는 본 방법이 실무에서 드러난 현행 지침의 논점을 보완할 수 있다는 점에서 합리성과 적용성을 보여준다. 상세 분할 및 가중평가에 근거한 합리적인 시스템 평가와 함께 과도 손상 부재의 특별 관리로 이원화함으로써 보수 보강에 대한 적정성과 경제성을 부여하고 안전성을 확보할 수 있다. 본 연구의 이원화된 평가방법은 가치공학의 적용 영역을 유지관리 단계로 확장한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.1089-1090
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• 2009

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.761-768
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• 1997

Recently, on account of the lack of skilled labor and the increase of labor costs, it has been more difficult the construction environment. Now new methods were developed and used many places. This study is concerning the structural performance of Composite Form Panel Method-one of the new methods-of the wall type. It is available to make monolithic system of bearing wall and half slab. This paper presented design and product data by experiments.

• 한국구조물진단유지관리공학회지
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• 제20권4호
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• pp.49-51
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• 2016

• 한국디지털건축인테리어학회논문집
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• 제4권2호
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• pp.44-51
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• 2004

It is generally known in seismic design that the beam yield type frames have more advantages than column yield type of which damage is likely to concentrate to any story. However we may design a building as a beam yield type, it becomes actually a column yield type collapse mode for slab floor diaphragm effect. Considering these points, the column yield type frames are selected and designed as the specimens. The object of this study is to grasp quantitatively the restoring force characteristic values and to estimate the seismic performances of column yield type steel rahmen.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.747-752
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• 1994

Ussing's flux ratio theorem (1978) reflects a reciprocal relationship behavior between the unidirectional fluxes in asymmetric steady diffusion-convection in a membrane slab. This surprising result has led to many subsequent studies in a wide range of applications, in particular involving linear models of time dependent problems in biology and physiology. Ussing's theorem and its extensions are inherently linear in character. It is of considerable interest to ask to what extent these results apply, if at all, in situations involving, for example, nonlinear reaction. A physiologically interesting situation has been considered by Weisiger et at. (1989, 1991, 1992) and by McNabb et al. (1990, 1991) who studied the role of albumin in the transport of ligands across aqueous diffusion barriers in a liver membrane slab. The results are that there exist reciprocal relationships between unidirectional fluxes in the steady state, although albumin is chemically interacting in a nonlinear way of the diffusion processes. However, the results do not hold in general at early times. Since this type of study first started, it has been speculated about when and how the Ussing's flux ratio theorem fails in a general diffusion-convection-reaction system. In this paper we discuss the validity of Ussing-type theorems in time-dependent situations, and consider the limiting time behavior of a general nonlinear diffusion system with interaction.