• Advances in Computational Design
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• 제4권4호
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• pp.343-365
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• 2019

Among the themes related to earthquake countermeasures at construction sites, those for tower cranes are particularly important. An accident involving the collapse of a crane during the construction of a skyscraper has serious consequences, such as human injury or death, enormous repair costs, and significant delays in construction. One of the causes of deadly tower crane collapses is the destruction of the site joints of the tower crane mast. This paper proposes a new design method by static elastoplastic finite element analysis using a supercomputer for the design of the end plate-type tensile bolted joints, which are generally applied to the site joints of a tower crane mast. This new design method not only enables highly accurate and reliable joint design but also allows for a design that considers construction conditions, such as the introduction of a pre-tension axial force on the bolts. By applying this new design method, the earthquake resistance of tower cranes will undoubtedly be improved.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.70-73
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• 2002

High frequency digital LSI circuits are usually composed of many sub-circuits coupled with interconnects. They sometimes causes serious problems of the fault switching by time-delays, crosstalks, reflections of signals and so on. Therefore, it is very important to develop a user-friendly simulator for solving these problems. Although a moment matching method is widely used as the reduction technique of interconnects, it may happen to arise erroneous results for evaluating the poles far from the origin. In this paper, we show an asymptotic method in the complex frequency-domain, where we calculate the exact poles and residues giving large effect to the transient responses. Then, the interconnects are replaced by the asymptotic equivalent circuits using the poles and residues. Thus, we can develop a users-friendly simulator using the equivalent circuits.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.38-45
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• 2011

Studies have shown that infrastructure projects have continued to experience significant delays and cost overrun over an extended period of time and no evidence of learning ever have happened [1] [2]. Various causes contribute to the bias towards overrun [3]. This study contributes to literature by developing and subsequently validating a set of hypothesized relationships between project complexity and project performance. The results show that project complexity is associated with both the magnitude and variance of overrun. Further, the extent and magnitude of the positive bias towards overrun are moderated by project complexity.

• Journal of information and communication convergence engineering
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• 제10권3호
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• pp.242-247
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• 2012

In the determination of suitable frame sizes associated with dynamic framed slotted Aloha used in radio frequency identification tag identification processes, the widely imposed constraint $L=2^Q$ often yields inappropriate values deviating far from the optimal values, while a straightforward use of the estimated optimal frame sizes causes frequent restarts of read procedures, both resulting in long identification delays. Taking a trade-off, in this paper, we propose a new method for determining effective frame sizes where the effective frame size changes in a multiple of a predetermined step size, namely ${\Delta}$. Through computer simulations, we show that the proposed scheme works fairly well in terms of identification delay.

• 대한전기학회논문지
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• 제40권1호
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• pp.58-66
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• 1991

In inverters, time delays are inserted in the switching signals to prevent the dc lind shortage. This causes detrimental effects on the performance of the inverters, that is, the fundamental voltage drop and the generation of low order harmonics. This paper derives simple formula to describe the time delay effects in PWM inverters, where the effects may become significant because of relatively high switching frequencies. To compensate the tice delay effects, this paper presents two methods which are suitable for sinusoidal PWM and memory-based PWM respectively. Both are simple, easy to implement, and are shown to be effective, through the experiments, in improving the output waveform of PWM inverters.

• Asian Pacific Journal of Cancer Prevention
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• 제15권4호
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• pp.1503-1510
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• 2014

Breast cancer bone metastasis causing severe morbidity is commonly encountered in daily clinical practice. It causes pain, pathologic fractures, spinal cord and other nerve compression syndromes and life threatening hypercalcemia. Breast cancer metastasizes to bone through complicated steps in which numerous molecules play roles. Metastatic cells disrupt normal bone turnover and create a vicious cycle to which treatment efforts should be directed. Bisphosphonates have been used safely for more than two decades. As a group they delay time to first skeletal related event and reduce pain, but do not prevent development of bone metastasis in patients with no bone metastasis, and also do not prolong survival. The receptor activator for nuclear factor ${\kappa}B$ ligand inhibitor denosumab delays time to first skeletal related event and reduces the skeletal morbidity rate. Radionuclides are another treatment option for bone pain. New targeted therapies and radionuclides are still under investigation. In this review we will focus on mechanisms of bone metastasis and its medical treatment in breast cancer patients.

• ETRI Journal
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• 제41권2호
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• pp.207-223
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• 2019

Network function virtualization can significantly improve the flexibility and effectiveness of network appliances via a mapping process called service function chaining. However, the failure of any single virtualized network function causes the breakdown of the entire chain, which results in resource wastage, delays, and significant data loss. Redundancy can be used to protect network appliances; however, when failures occur, it may significantly degrade network efficiency. In addition, it is difficult to efficiently map the primary and backups to optimize the management cost and service reliability without violating the capacity, delay, and reliability constraints, which is referred to as the reliability-aware service chaining mapping problem. In this paper, a mixed integer linear programming formulation is provided to address this problem along with a novel online algorithm that adopts the joint protection redundancy model and novel backup selection scheme. The results show that the proposed algorithm can significantly improve the request acceptance ratio and reduce the consumption of physical resources compared to existing backup algorithms.

• Journal of Preventive Medicine and Public Health
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• 제26권4호
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• pp.650-660
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• 1993

This study aims to describe the causes of medically unnecessary hospital stay at a teaching tertiary hospital, using modified version of Delay Tool in which the causes of delay are divided into slx major categories : delay related to test scheduling, test results, surgery, medical staff, patient/family, and administration. For the analysis of hospital stay, 6,479 inpatient-days were reviewed in two medical and four surgical departments for one month. Initially inappropriate hospital stays were identified using Appropriateness Evaluation Protocol (AEP), and causes of delay listed in Delay Tool were assigned to each of them. In both medical and surgical services, the most important cause of delay was related to medical staffs, ranging from 3.6% to 51.6% of total inpatient days. Next important category was delay related to test scheduling in medical services ($4.7{\sim}9.2%$), and delay related to surgery in surgical services ($7.3{\sim}15.0%$). Among subcategories of delay related to medical staffs, delay due to conservative care was the most important cause of inappropriate hospital stay ($2.9{\sim}6.4%$). Each clinical departments had different distribution among delay categories, which could not be fully justified by their clinical charateristics. The Delay Tool would be helpful in exploring factors related to the inefficient use of hospital beds. As a measurement tool of inappropriate hospital stay, however, the Delay Tool should be refined in the definitions of categories and its contents.

• Journal of Construction Engineering and Project Management
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• 제4권2호
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• pp.12-22
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• 2014

Over the last decade, Saudi Arabia has experienced significant economic increases as evidenced by the 30% growth in its gross domestic product; furthermore, the construction industry has increased 10% in the same time period. Due to this significant growth, the construction industry is encountering issues related to construction quality resulting in significant waste and associated environmental impacts. In this research, we applied our previously developed framework that integrates three different methods-Lean, Green, and Six-sigma - to a residential construction complex in Saudi Arabia. Our aim of this case study was to explore the application of the framework in practice to glean quantitative results and further validate the framework. In the case study, we used the developed framework to identify a significant issue related to quality and delays - final completion of 53 residential units was delayed because of failed exterior buildings surfaces. We then used the framework to define the causes behind the defects via a field investigation of the 53 units. Of the defect, construction execution was responsible for 43% of the defect, 31% untrained workers, 19% unfavorable construction weather condition, with 7% accounting for other issues. A procedure was developed in concert with the construction manager and overall developer reducing the amount of rework and waste causes revealed by the field examination and the framework. Although two steps were added to the original construction process to overcome waste causes, still save a lot of resources and reduces environmental impact. In summary, we found that the Lean, Green, Six-sigma framework increased productivity, quality, and reduced waste.

• 한국항공운항학회지
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• 제25권3호
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• pp.81-88
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• 2017

Aircraft maintenance failure doesn't only threaten flight safety but also causes significant economic losses such as flight delays, flight cancellations, air turn backs and diversion and so on. Therefore, the efforts should be made to detect the contributing factors that cause such maintenance failure and eliminate them. In this study, by analyzing factors contributing to system failure using the Maintenance Error Decision Aid (MEDA) model based on stochastic relations between the contribution factors, system failure and events, we will draw a improvement plan to aircraft maintenance defects.