• Steel and Composite Structures
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• 제37권6호
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• pp.741-759
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• 2020

Steel plate-concrete composite slabs provide attractive features, such as more effective loading transfer, and more cost-effective stay-in-place forms, thereby enabling engineers to design more high-performance light structures. Although significant studies in the literatures have been directed toward designing and implementing the steel plate-concrete composite beams, there are limited data available for understanding of the composite slabs. To fill this gap, nine the composite slabs with different variables in this study were tested to unveil the impacts of the critical factors on the ultimate strength behavior. The key information of the findings included sample failure modes, crack pattern, and ultimate strength behavior of the composite slabs under either four-point or three-point loading. Test results showed that the failure modes varied from delamination to shear failures under different design factors. Particularly, the shear stud spacing and thicknesses of the concrete slabs significantly affected their ultimate load-carrying capacities. Moreover, an analytical model of the composite slabs was derived for determining their ultimate load-carrying capacity and was well verified by the experimental data. Further extensive parametric study using the proposed analytical methods was conducted for a more comprehensive investigation of those critical factors in their performance. These findings are expected to help engineers to better understand the structural behavior of the steel plate-concrete composite slabs and to ensure reliability of design and performance throughout their service life.

• Structural Engineering and Mechanics
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• 제64권4호
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• pp.437-447
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• 2017

Explicit expressions for rapid prediction of inelastic design quantities (considering cracking of concrete) from corresponding elastic quantities, are presented for multi-storey composite frames (with steel columns and steel-concrete composite beams) subjected to service load. These expressions have been developed from weights and biases of the trained neural networks considering concrete stress, relative stiffness of beams and columns including effects of cracking in the floors below and above. Large amount of data sets required for training of neural networks have been generated using an analytical-numerical procedure developed by the authors. The neural networks have been developed for moments and deflections, for first floor, intermediate floors (second floor to ante-penultimate floor), penultimate floor and topmost floor. In the case of moments, expressions have been proposed for exterior end of exterior beam, interior end of exterior beam and both interior ends of interior beams, for each type of floor with a total of twelve expressions. Similarly, in the case of deflections, expressions have been proposed for exterior beam and interior beam of each type of floor with a total of eight expressions. The proposed expressions have been verified by comparison of the results with those obtained from the analytical-numerical procedure. This methodology helps to obtain the inelastic design quantities from the elastic quantities with simple calculations and thus would be very useful in preliminary design.

• Steel and Composite Structures
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• 제5권4호
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• pp.259-269
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• 2005

Many slab-on-girder bridges around the world are being assessed because they are approaching the end of their anticipated design lives or codes are permitting higher allowable loads. Current analytical techniques assume that the concrete and steel components act independently, typically requiring full-scale load testing to more accurately predict the remaining strength or endurance of the structure. However, many of the load tests carried out on these types of bridges would be unnecessary if the degree of interaction resulting from friction at the steel-concrete interface could be adequately modeled. Experimental testing confirmed that interface friction has a negligible effect on the flexural capacity of a slab-on-girder beam however, it also showed that interface friction is significant under serviceability loading. This has led to the development of an improved analytical technique which is presented in this paper and referred to as the slab-on-girder mixed analysis service load assessment approach.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2012년도 제45차 동계학술발표논문집 20권1호
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• pp.183-186
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• 2012

최근 스마트폰의 활용이 급격하게 증가하면서 스마트폰을 위한 다양한 서비스, 즉 어플리케이션(앱)이 개발되고 있다. 이러한 컴퓨팅 패러다임의 변화에 따라 통계 분야에서도 스마트폰을 위한 통계지리정보서비스 개발이 요구된다. 현재까지 대부분의 서비스는 웹을 기반으로 제공되고 있으며, 최근에 국내 통계청에서 S-통계내비게이터 모바일 서비스를 제공하고 있다. 그러나 이러한 서비스들은 사용자 인터페이스 및 기능적인 측면에서 여러 가지 문제점을 지닌다. 특히 단순 통계지리정보서비스만을 제공함으로써 사용자에게 다양한 분석 결과를 제공하지 못한다. 이 논문에서는 사용자에게 보다 유용한 복합 통계지리정보서비스를 제공할 수 있는 새로운 통계지리정보 앱을 제안한다. 제안한 통계지리정보 앱은 다양한 복합 통계 분석 결과를 지리정보와 함께 제공함으로써, 사용자들에게 양질의 통계지리정보서비스 결과를 제공할 수 있다.

• 한국산업보건학회지
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• 제34권1호
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• pp.57-66
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• 2024

Objective: Chronic obstructive pulmonary disease (COPD) is characterized by progressive airflow obstruction that is only partly reversible, inflammation in the airways, and systemic effects. This study aimed to investigate the association between low peripheral oxygen saturation levels (SpO₂), and composite indices predicting death in male patients with (COPD). Method: A total of 140 participants with post-bronchodilator FEV₁/FVC ratio less than 0.7 were included. Three composite indices (ADO, DOSE, BODEx) were calculated using six variables such as age (A), airflow obstruction (O), body mass index (B), dyspnea (D), exacerbation history (E or Ex), and smoking status (S). Severity of airflow limitation was classified according to Global Initiative for Obstructive Lung Disease (GOLD) guidelines. SpO₂ was measured by pulse oximetry, and anemia and iron deficiency were assessed based on blood hemoglobin levels and serum markers such as ferritin, transferrin saturation, or soluble transferrin receptor. Results: Participants with low SpO₂ (<95%) showed significantly lower levels of %FEV₁ predicted (p=0.020) and %FEV₁/FVC ratio (p=0.002) compared to those with normal SpO₂ levels. The mMRC dyspnea scale (p<0.001) and GOLD grade (p=0.002) showed a significant increase in the low SpO₂ group. Receiver Operating Characteristic analysis revealed higher area under the curve for %FEV₁ (p=0.020), %FEV₁/FVC(p=0.002), mMRC dyspnea scale (p=0.001), GOLD grade (p=0.010), ADO (p=0.004), DOSE (p=0.002), and BODEx (p=0.011) in the low SpO₂ group. Conclusion: These results suggest that low SpO₂ levels are related to increased airflow limitation and the composite indices of COPD.

• Steel and Composite Structures
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• 제17권6호
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• pp.907-927
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• 2014

Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of $1450kg/m^3$ has been developed and used in the steel-concrete-steel (SCS) sandwich structures. ULCC was adopted as the core material in the SCS sandwich composite beams to reduce the overall structural weight. Headed shear studs working in pairs with overlapped lengths were used to achieve composite action between the core material and steel face plates. Nine quasi-static tests on this type of SCS sandwich composite beams were carried out to evaluate their ultimate strength performances. Different parameters influencing the ultimate strength of the SCS sandwich composite beams were studied and discussed. Design equations were developed to predict the ultimate resistance of the cross section due to pure bending, pure shear and combined action between shear and moment. Effective stiffness of the sandwich composite beam section is also derived to predict the elastic deflection under service load. Finally, the design equations were validated by the test results.

• 한국병원경영학회지
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• 제25권3호
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• pp.78-86
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• 2020

Purposes: This study purposed to identify factors influencing the composite quality score from the quality assessment program for long-term care hospitals Methodology: The study variables was obtained from HIRA(Health Insurance Review and Assessment Service): the composite quality scores and hospital variables such as number of doctors, nurses, beds, medical technicians, medical equipments, administrative region, ownerships from 3rd (2010) to 7th (2018) quality assessment program. National Statistical Portal(www.kosis.go.kr) provided the number of senior citizens aged over 65 in city·county·district area. SAS 9.4 was used for the data processing and used to analyze the data. Findings: The results showed that composite quality score increased past 9 years. Hospital variables such as number of doctor, nurse, medical technicians, bed and public hospitals had significant positive relationship with the composite quality score. Administrative region(district) showed higher scores compare to that of city. Compare to the score of quality assessment year(2010), as the assessment year move to 2012, 2013, 2015, 2018, results showed higher significant positive coefficients. Practical Implication: Continuously improve the performance of long-term care hospitals, current quality assessment program are needed to update their system such as adopting indicators measuring the service process, or compensating the cost for quality assessment program. It will enable to provide more reasonable and accurate performance assessment scores.

• 정보처리학회논문지A
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• 제17A권2호
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• pp.93-102
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• 2010

유비쿼터스 환경에서는 사용자의 주변 환경에서 발생할 수 있는 상황이 매우 다양하므로, 이에 대응하기 위한 자동화 서비스의 개발이 요구된다. 그러나 기존의 상황인지 기반 워크플로우 시스템들은 단일 워크플로우 서비스만을 제공할 수 있으므로, 다수의 워크플로우 조합을 통해 복합적이고 다양한 서비스를 제공하는데 제약이 있다. 이를 위해 본 논문에서는 다수의 워크플로우에 존재하는 개별적인 서비스 흐름을 하나의 워크플로우로 통합 표현할 수 있는 상황인지 기반의 워크플로우 언어인 CAWL(Context-Aware Workflow Language)를 기반으로 하는 워크플로우 시스템을 제안한다. 제안하는 시스템은 CAWL를 이용하여 작성한 시나리오를 바탕으로 사용자에게 다양한 복합 워크플로우 서비스를 제공할 수 있다. 또한 각각 존재하는 다수의 워크플로우를 복합 워크플로우 서비스를 구성하기 위한 일부로써 재사용할 수 있으므로, 자동화 서비스 개발의 효율성을 증대시킬 수 있다.

• 한국경영정보학회:학술대회논문집
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• 한국경영정보학회 2007년도 추계학술대회
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• pp.377-382
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• 2007

To transform the enterprise system into the 'Real Time Enterprise' with respect to IT, I suggest the conceptual application model which is composed of pieces(components) extracted from different packaged applications working in a heterogeneous environment based on the 'business activity' in other words, business services provided by internal (inter-enterprise) and external (extended enterprise) application to support a business activity within in an enterprise and the design mechanism focusing service tier which acts as intermediate tier within application architecture.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.183-186
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• 2003

Long shafts for power transmission should transmit torsional load with vibrational stability. Hybrid shafts made of unidirectional fiber-reinforced composite and metal have high fundamental bending natural frequency as well as high torque transmission capability. However, thermal residual stresses due to the coefficient difference of thermal expansion of the composite and metal are developed so that the high residual stresses decrease fatigue resistance of the hybrid shafts, especially at low operating temperatures. In this work, axial compressive preload was given to the shaft in order to change the residual stresses. Static and fatigue torsional tests were performed and correlated with stress analyses with respect to the preload and service temperature.