• Wind and Structures
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• 제39권3호
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• pp.207-222
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• 2024

This paper presents a numerical simulation method for snow drift that takes into account the cohesion effect of snow particles. The critical state of free collapse accumulation of idealized snow particles is used to indirectly infer the effect of interparticle interactions on snow transport and re-accumulation. With the help of the Hertz-Mindlin with JKR cohesion contact model, the particle angle of repose is calibrated with a number of contact parameters through numerical experiment. The surface energy for a given property of snow particles is determined using the observed snow angle of repose, and a continuous-discrete snow drift two-way coupled numerical model incorporating these optimized contact parameters is developed. The snow redistribution pattern on a stepped flat roof structure is simulated, and the results are found to be consistent with those of the field measured in terms of phenomena and general laws, verifying the achievability and effectiveness of the presented method. To eliminate the influence of environmental conditions, wind tunnel tests are also conducted, and it is found that the reconstructed depth and reaccumulated angle of snowdrift resulting from the numerical simulation are in closer agreement with the experimental results, further confirming the enhancement achieved by introducing the contact effect.

• Steel and Composite Structures
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• 제18권4호
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• pp.873-887
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• 2015

The continuous composite I-girder should have a sufficient rotation capacity (or ductility) to redistribute the negative bending moment into an adjacent positive bending moment region. However, it is generally known that the ductility of the high strength steel is smaller than that of conventional steel, and application of high strength steel can cause ductility problems in a negative moment region of the I-girder. In this study, moment redistribution of the continuous composite I-girder with high strength steel was studied, where high strength steel with yield stress of 690 MPa was considered (the ultimate stress of the steel was 800 MPa). The available and required rotation capacity of the continuous composite I-girder with high strength steel was firstly derived based on the stress-strain curve of high strength steel and plastic analysis, respectively. A large scale test and a series of non-linear finite element analysis for the continuous composite I-girder with high strength steel were then conducted to examine the effectiveness of proposed models and to investigate the effect of high strength steel on the inelastic behavior of the negative bending moment region of the continuous composite I-girder with high strength steel. Finally, it can be found that the proposed equations provided good estimation of the requited and available rotation capacity of the continuous composite I-girder with high strength steel.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권10호
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• pp.3321-3341
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• 2014

This paper investigates the outage performance and optimization for the four-phase two-way transmission network with an energy harvesting (EH) relay. To enable the simultaneous information processing and energy harvesting at the relay, we firstly propose a power splitting-based two-way relaying protocol (PSTWR). Then, we discuss its outage performance theoretically and derive an explicit expression for the system outage probability. In order to find the optimal system configuration parameters such as the optimal power splitting ratio and the optimal transmit power redistribution factor, we formulate an outage-minimized optimization problem. As the problem is difficult to solve, we design a genetic algorithm (GA) based algorithm for it. Besides, we also investigate the effects of the power splitting ratio, the power redistribution factor at the relay, and the source to relay distance on the system outage performance. Finally, extensive simulation results are provided to demonstrate the accuracy of the analytical results and the effectiveness of the GA-based algorithm. Moreover, it is also shown that, the relay position greatly affects the system performance, where relatively worse outage performance is achieved when the EH relay is placed in the middle of the two sources.

• Journal of Sport and Applied Science
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• 제6권4호
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• pp.11-23
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• 2022

New insights into the aetiology of anaemia in athletes have been discovered in recent years. From hemodilution and redistribution, which are thought to commit to so-called "sports anaemia," to iron deficiency triggered by higher requirements, dietary requirements, decreased uptake, enhanced losses, hemolysis, and sequester, to genetic factors of different types of anaemia (some related to sport), anaemia in athletes necessitates a careful and multisystem methodology. Dietary factors that hinder iron absorption and enhance iron bioavailability (e.g., phytate, polyphenols) should be considered. Celiac disease, which is more common in female athletes, may be the consequence of an iron deficiency anaemia that is unidentified. Sweating, hematuria, gastrointestinal bleeding, inflammation, and intravascular and extravascular hemolysis are all ways iron is lost during strength training. In training, evaluating the iron status, particularly in athletes at risk of iron deficiency, may work on improving iron balance and possibly effectiveness. Iron status is influenced by a healthy gut microbiome. To eliminate hemolysis, athletes at risk of iron deficiency should engage in non-weight-bearing, low-intensity sporting activities.

• Structural Engineering and Mechanics
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• 제42권6호
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• pp.799-813
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• 2012

Five two-span reinforced concrete (RC) slabs and seven two-span RC beams were tested under the ISO 834 standard fire with different durations. CFRP strengthening was then applied to some of the specimens after the damaged concrete was removed from the specimens and replaced with polymer mortar. All the specimens were loaded to failure to investigate the influence of fire-damage and the effectiveness of strengthening methods. Test results indicated that the flexural capacities of specimens decrease with the fire duration increases. Moreover, fire exposure had more significant effect on the flexural rigidity than on the bearing capacity of the specimens. After rehabilitation, the bearing capacities of specimens reached or even exceeded that of the reference RC specimen, and the strengthening methods seemed to have limited effect on flexural rigidity recovery. From the analysis of moment redistribution of tested beams, elevated temperature is found having different impacts on sagging moment region and hogging moment region. The damage of RC continuous member is definitely a comprehensive response of different regions.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.176-179
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• 2002

In recent years, an increasing amount of computer network research has focused on the problem of cluster system in order to achieve higher performance and lower cost. The load unbalance is the major defect that reduces performance of a cluster system that uses parallel program in a form of SPMD (Single Program Multiple Data). Also, the load unbalance is a problem of MPP (Massive Parallel Processors), and distributed system. The cluster system is a loosely-coupled distributed system, therefore, it has higher communication overhead than MPP. Dynamic load balancing can solve the load unbalance problem of cluster system and reduce its communication cost. The cluster systems considered in this paper consist of P heterogeneous nodes connected by a switch-based network. The master node can predict the average execution time of tasks for each slave node based on the information from the corresponding slave node. Then, the master node redistributes remaining tasks to each node considering the predicted execution time and the communication overhead for task migration. The proposed dynamic load balancing uses execution time prediction to optimize the task redistribution. The various performance factors such as node number, task number, and communication cost are considered to improve the performance of cluster system. From the simulation results, we verified the effectiveness of the proposed dynamic load balancing algorithm.

• Structural Engineering and Mechanics
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• 제48권5호
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• pp.615-642
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• 2013

In this paper a study on prestressed concrete slab bridges is presented. A design philosophy based on the concept of load balancing through prestressing is proposed in order to minimize the effects of delayed deformations due to creep. Aspects related to the stress redistribution inside these bridges for time-dependent phenomena are analyzed and discussed, by applying the principles of aging linear visco-elasticity. Prestressing is seen as an equivalent external load which counterbalances the permanent loads applied to the bridge, nullifying the elastic deflections due to sustained loads, and thus avoiding the related delayed deformations. An optimization of the structural behavior through the use of one-way prestressing is achieved. The determination of a convenient variable depth of slab bridges and the correspondent layout of tendons is considered as a useful means for applying the load balancing concept in actual cases of structures like long cantilevers or bridge decks. A case-study related to the slab bridges built 30 years ago at Jeddah in Saudi Arabia is presented and discussed, in order to show the effectiveness of the proposed approach to the conceptual design of prestressed concrete bridges.

• 대한기계학회논문집A
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• 제22권2호
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• pp.258-267
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• 1998

This study reviews the influence function method(IFM) for calculating stress intensity factors (SIFs, K) and modifies it to apply for the estimating the residual fatigue life for the cracked components under complex stress fields. An IFM has been developed to analyze SIFs for surface cracks which are subjectedto nonuniformly distributed stresses. Through elastic superposition, the influence function method properly accounts for redistribution of stress as the crack grows through the component. This influence function is unique to the given geometry and independent of the loading. Some examples have been provided to show the effectiveness of the IFM including the distributions of K in a residual stress field. The significant effect of residual stress upon fatigue crack growth in a welded component has been demonstrated with the IFM.

• 한국사회정책
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• 제25권3호
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• pp.3-35
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• 2018

이 글은 기본소득의 재정적 실현가능성과 기존 사회보장제도의 대안으로서의 효용을 부정하는 양재진(2018) 등의 주장을 비판적으로 검토하고, 효과적이고 효율적인 기본소득안 설계를 위한 몇 가지 제안을 하고자 한다. 재정적 실현가능성에 대해서는 역진적인 조세지출의 기본소득으로의 전환을 통해 세율 인상 없이도 상당한 규모의 기본소득 도입이 가능하며, 이는 상위층을 제외한 대다수에게 실질적인 감세 내지 현금지원 효과를 냄을 강조한다. 또한 기본소득의 과세소득화와 기존 현금급여 수급자와 수급액의 축소로 재정절감이 가능함을 주장한다. 소득재분배의 효과 면에서 기존 사회보장제도의 선별 능력이 좋지 않으며, 보편적인 복지가 선별적인 복지보다 재분배 효과에서 우월하다는 "재분배의 역설"이 기본소득에도 적용될 수 있음을 주장한다. 또, 재정중립적인 기본소득안의 재분배효과를 가상의 시나리오를 통해 보여준 후 국내외의 관련 연구들을 검토하여 기본소득이 사회보험이나 공적서비스 확대 이상으로 재분배효과를 나타내며 추가적인 여러 장점이 있음을 주장한다. 끝으로 이러한 연구들을 위한 인프라로서 가구조사 자료와 행정자료를 통합하고 각종 조세와 복지지출 관련 규정들을 수식화하여 결합한 제대로 된 조세-급여 모델 구축의 필요성을 강조한다.

• 사회복지연구
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• 제49권2호
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• pp.211-232
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• 2018

이 연구의 목적은 복지체제에 따라 복지태도의 유형이 구분되는지를 검증하는 데 있다. 구체적으로 불평등 완화의 국가역할 만족도와 요구도가 복지체제별로 구분되는지를 확인하고자 했다. 이를 위해 유럽사회조사(European Social Survey) 6차 자료(2012년)와 유럽연합통계국(Eurostat) 자료를 활용하여 24개 유럽국가의 비교분석을 수행했다. 주요 분석결과는 다음과 같이 정리된다. 첫째, 복지체제별로 불평등 완화에 대한 국가역할 만족도와 요구도에 차이가 존재했다. 대체로 북유럽 국가에서 만족도가 높았고, 남유럽과 동유럽 국가에서 요구도가 높았다. 둘째, 불평등 완화에 대한 국가역할 만족도가 높고, 1인당 복지지출 수준이 높으며, 재분배 효과성이 강한 국가일수록 국가역할 요구도가 낮은 상관관계가 존재했다. 셋째, 복지체제에 따라 복지태도의 유형이 구분되고 있었다. 특히 북유럽 국가들은 불평등 완화에 대한 국가역할 만족도가 높은 반면 요구도가 낮은 군집으로 수렴되고 있었다. 이들 국가들은 높은 복지지출 수준과 강한 재분배 효과성이라는 특징을 가지고 있었다. 이 연구는 이상의 결과를 바탕으로 정책적 제언을 제시하였다.