• Journal of Ocean Engineering and Technology
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• v.29 no.3
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• pp.255-262
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• 2015

The present study developed a numerical simulation tool for the coupled dynamic analysis of multiple turbines on a single floater (or Multiple Unit Floating Offshore Wind Turbine (MUFOWT)) in the time domain, considering the multiple-turbine aero-blade-tower dynamics and control, mooring dynamics, and platform motions. The numerical tool developed in this study was designed based on and extended from the single-turbine analysis tool FAST to make it suitable for multiple turbines. For the hydrodynamic loadings of floating platform and mooring-line dynamics, the CHARM3D program developed by the authors was incorporated. Thus, the coupled dynamic behavior of a floating base with multiple turbines and mooring lines can be simulated in the time domain. To investigate the effect of asymmetric aerodynamic loading on the global performance and mooring line tensions of the MUFOWT, one turbine failure case with a fully feathered blade pitch angle was simulated and checked. The aerodynamic interference between adjacent turbines, including the wake effect, was not considered in this study to more clearly demonstrate the influence of the asymmetric aerodynamic loading on the MUFOWT. The analysis shows that the unbalanced aerodynamic loading from one turbine in MUFOWT may induce appreciable changes in the performance of the floating platform and mooring system.

• International Journal of Control, Automation, and Systems
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• v.3 no.2
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• pp.166-172
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• 2005

With the development of RAIM techniques for single failure, increasing interest has been shown in the multiple failure problem. As a result, numerous approaches have been used in attempts to tackle this problem. This paper considers the two failure problem with total least squares (TLS) technique, a solution that has rarely been addressed because TLS requires an immense number of computations. In this paper, the special form of the observation matrix H, (that is, one column is exactly known) is exploited so as to develop an algorithm in a sequential form, thereby reducing computational load. The algorithm permits the advantages of TLS without the excessive computational burden. The proposed algorithm is verified through a numerical simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2627-2631
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• 2003

With the development of RAIM techniques for single failure, there has been increasing interest in the multiple failure problem. There have been many approaches to tackle the problem from various points of view. This paper approaches to two failure problem with total least squares (TLS) technique, which has rarely been addressed because TLS requires a great number of computations. In this paper, the special form of the observation matrix H, that is, one column is exactly known, is exploited so as to develop an algorithm in a sequential form, which reduces computational burden. The algorithm makes us enjoy the advantages of TLS without much computational burden. The proposed algorithm is verified through a numerical simulation.

• Journal of Chest Surgery
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• v.26 no.1
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• pp.59-63
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• 1993

A clinical evaluation was performed with a population of 49 patients of chest trauma, who were diagnosed to undergo ventilator therapy, and had gone through ventilator therapy at the Department of Thoracic and Cardiovascular Surgery, Kyungpook University Hospital. One of most common causes of chest trauma was vehicle accidents [77.5%] with the prevalent age group being their forties. The common findings were multiple rib fractures [89.8%], hemopneumothrax [81.6%], lung contusion [61.2%] and flail chest [44.9%]. Their common combined injuries were the orthopedics and neurosugical injuries [86.7%]. Complications caused by chest trauma were pneumonia, respiratory failure, atelectasis, barotrauma and empyema. Pulmonary infections were commonly associated with mechanical ventilation in the long term group and were best prevented by using bronchial hygiene therapy.The mortality rate was 5.8% of the total patients and that was 38.8% of the patients, who needed ventilator therapy. The causes of death were pneumonia, respiratory failure, acute renal failure and hypovolemic shock. Mechanical ventilation has an important place in the treatment of patients with severe chest trauma.

• The Korean Journal of Pain
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• v.6 no.2
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• pp.258-260
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• 1993

We experienced a rare case of erection failure which developed after unilateral lumbar sympathetic block. A 43 year old male patient suffering from reflex sympathetic dystrophy, which had developed after multiple communitted fracture of the right ankle, underwent right lumbar sympathetic block with 99.9% alcohol. The effectiveness of the lumbar sympathetic block was evaluated by monitoring the clinical symptoms, signs and temperature changes by digital infrared thermographic imaging. Postoperatively, the temperature of the affected side limb rose about $2^{\circ}C$, but the patient's conditions gradually returned to normal. Ten days after the operation the patient complainted of difficulty in achieving an erection. The patient was examined by a urologst without much results. The patient gradually recovered his ability to achieve an erection approximately 5 weeks after the lumbar sympathetic block.

• Steel and Composite Structures
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• v.20 no.6
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• pp.1221-1236
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• 2016

Modular structures consist of standardized modules and their connections. A modular bridge pier is proposed to accelerate bridge construction. Multiple concrete-filled steel tubes (CFTs) using commercial steel tubes were chosen as the main members. Buckling restrained bracings and enhanced connection details were designed to prevent premature low-cycle fatigue failure upon cyclic loading. The pier had a height of 7.95 m, widths of 2.5 m and 2.0 m along the strong and weak axis, respectively. Cyclic tests were performed on the modular pier to investigate structural performance. Test results showed that four CFT columns reached yielding without a premature failure of the bracing connections. The ultimate capacity of the modular pier was reasonably estimated based on the plastic-hinge-analysis concept. The modular CFT pier with enhanced bracing showed improved displacement ductility without premature failure at the welding joints.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.3
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• pp.301-311
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• 1990

A multiple controller structure consisting of a typical feedback controller and an additive redundant controller is proposed for enhancing the reliability of the control system. For the case where the main controller is chosen as a pole assignment controller with input/output measurements and the redundant controller as the Model Reference Adaptive Controller (MRAC) whose reference model is the closed-loop combination of the plant and the main controller, it is proven that the tracking error between the command input and plant output converges to zero under failure in one of the controllers or parameter perturbations of the plant, and further that the reliability measured by Mean Time To Failure (MTTF) is greater than that of the system with only a single main controller. A simulation Example is provided to illustrate reliable operation of the proposed control system against the controller failure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.301-305
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• 2005

This paper introduces a novel technique to detect and isolate the failures of multiple actuators connected to a system. Failure of actuator considered in this study could be any type of erroneous input that is different from commanded one. The interaction matrix technique allows the development of input-output equations that are only influenced by one target input. These input-output equations serve as an effective toot to monitor the integrity of each actuator regardless of the status of the other actuators. The method is capable of real-time actuator failure detection and isolation under any type of input excitation. The laboratory experiment using 8-bay NASA truss structure verifies the feasibility of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4287-4306
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• 2016

Network resilience provides an effective way to overcome the problem of network failure and is crucial to Internet protocol (IP) network management. As one of the main challenges in network resilience, recovering from link failure is important to maintain the constancy of packets being transmitted. However, existing failure recovery approaches do not handle the traffic engineering problem (e.g., tuning the routing-protocol parameters to optimize the rerouting traffic flow), which may cause serious congestions. Moreover, as the lack of QoS (quality of service) restrictions may lead to invalid rerouting traffic, the QoS requirements (e.g., bandwidth and delay) should also be taken into account when recovering the failed links. In this paper, we first develop a probabilistically correlated failure model that can accurately reflect the correlation between link failures, with which we can choose reliable backup paths (BPs). Then we construct a mathematical model for the failure recovery problem, which takes maximum rerouting traffic as the optimizing objective and the QoS requirements as the constraints. Moreover, we propose a heuristic algorithm for link failure recovery, which adopts the improved k shortest path algorithm to splice the single BP and supplies more protection resources for the links with higher priority. We also prove the correctness of the proposed algorithm. Moreover, the time and space complexity are also analyzed. Simulation results under NS2 show that the proposed algorithm improves the link failure recovery rate and increases the QoS satisfaction rate significantly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.5 s.236
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• pp.754-761
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• 2005

The 40\% of wall thickness criterion which has been used as a plugging rule of steam generator tubes is applicable only to a single cracked tube. In the previous studies performed by authors, several global failure prediction models were introduced to estimate the failure loads of steam generator tubes containing two adjacent parallel axial through-wall cracks. These models were applied for thin plates with two parallel cracks and the COD base model was selected as the optimum one. The objective of this study is to verify the applicability of the proposed optimum global failure prediction model for real steam generator tubes with two parallel axial through-wall cracks. For the sake of this, a series of plastic collapse tests and finite element analyses have been carried out fur the steam generator tubes with two machined parallel axial through-wall cracks. Thereby, it was proven that the proposed optimum failure prediction model can be used as the best one to estimate the failure load quite well. Also, interaction effects between two adjacent cracks were assessed through additional finite element analyses to investigate the effect on the global failure behavior.