• Smart Structures and Systems
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• 제25권6호
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• pp.657-668
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• 2020

A novel multistage approach is developed for structural model updating based on sensitivity ranking of the selected updating parameters. Modal energy-based sensitivities are formulated, and maximum-normalized indices are designed for sensitivity ranking. Based on the ranking strategy, a multistage approach is proposed, where these parameters to be corrected with similar sensitivity levels are updated simultaneously at the same stage, and the complete procedure continues sequentially at several stages, from large to small, according to the predefined levels of the updating parameters. At every single stage, a previously developed cross model cross mode (CMCM) method is used for structural model updating. The effectiveness and robustness of the multistage approach are investigated by implementing it on an offshore structure, and the performances are compared with non-multistage approach using numerical and experimental vibration information. These results demonstrate that the multistage approach is more effective for structural model updating of offshore platform structures even with limited information and measured noise. These findings serve as a preliminary strategy for structural model updating of an offshore platform in service.

• 한국항공운항학회지
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• 제27권3호
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• pp.70-81
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• 2019

The effects of weather on aircraft operations are predominant. In particular, severe weather, such as fog, strong winds, rainfall and snow, can cause delays, diversion or cancellation of operations. Of these, fog is considered the main reason for restricting aircraft operations. Meanwhile, Precision instrument approach using instrument landing system(ILS) has allowed aircraft to land safely even in situations where visibility is limited. However, the precision instrument approach require not only the performance of the aircraft but also the enhancement of the runway. In November 2018, Gimpo international Airport raised the category of the runway 14R from CAT-IIIa to CAT-IIIb to improve aviation safety and operational efficiency. Based on this, the research presented a methodology for estimating benefits according to the category upgrade of the precision approach runway, and estimated the benefits to Gimpo International Airport based on the methodology presented.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.85-89
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• 2001

Hamiltonian modeling approach has been extensively adopted for rigid body dynamics whereas its usage for deforming flexible continuum dynamics has been limited. A set of Hamilton＇s equations for flexible body motion with finite deformation has been derived and applied for a nonlinear impact problem.

• Clinics in Shoulder and Elbow
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• 제13권2호
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• pp.293-298
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• 2010

목적: 주관절은 굴곡 구축 40도 이상 굴곡 제한 105도 이하일 경우 일상 생활에 상당한 장애를 일으킬 수 있는 관절로 그 치료의 정도 및 시기를 결정하기가 상당히 어려운 것으로 알려져 있다. 이에 이 종설에서는 현재까지 인정된 주관절 구축의 수술적 접근법에 대하여 고찰하여 보도록 하겠다. 대상 및 방법: 환자의 병력을 포함하여 충분한 임상적 조사를 하는 것이 중요하다. 그리고 방사선학적 방법을 이용하여 환자의 주관절 구축에 대한 원인 및 상태를 정확히 파악하고 그에 적합한 수술법을 선택한다. 수술법으로는 관절경적 유리술 (arthroscopic release) 및 관혈적 유리술 (Open release), 견인 관절 성형술 (Distraction Arthroplasty), 인공관절 치환술 (Total elbow replacement)이 있으며 관혈적 유리술은 4가지 기본 도달법 -전방 도달법 (anterior approach), 내측 도달법 (medial "over the top" approach), 제한된 외측 도달법 (limited lateral approach: column procedure) 광범위 후방 도달법 (posterior extensile approach)-으로 분류될 수 있다. 결과 및 결론: 현재 주관절 구축의 수술은 관절경의 발달로 인한 최소 침습적인 방법이 대두되고 있으나 그 경과의 판정은 아직 미미하며 그에 대한 문헌 보고가 많지 않은 상태로 고식적인 개방성 접근법을 이용하는 것을 원칙으로 하고 있으며 접근법에 따른 분류를 사용하고 있다.

• Journal of Korean Neurosurgical Society
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• 제43권5호
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• pp.232-236
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• 2008

Total laminectomy for the removal of intradural-extramedullary spinal cord tumors has been used widely, but postoperative complications often develop, such as kyphosis, spinal instability, and persistent back pain. In this study, we evaluated seven patients with intradural-extramedullary spinal cord tumors with respect to the value of unilateral limited laminectomy. Our cases included six schwannomas, and one meningioma. The cervical region was involved in four cases, the thoracolumbar region in two cases, and the lumbar region in one case. The rationale for choosing a unilateral approach is to preserve musculoligamentous attachments and posterior bony elements as much as possible. The patients were mobilized on the third postoperative day and preoperative neurological symptoms were recovered within a few weeks. We did not observe any complication relating to unilateral limited laminectomy and at follow-up evaluation (at 3 and 12 months postoperatively), none of the patients showed spinal deformity or spinal instability. We think that the unilateral limited laminectomy is a safe and efficient technique for the treatment of intradural-extramedullary spinal cord tumors. We suggest that this technique is one of the best treatments for these tumors.

• 한국시뮬레이션학회논문지
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• 제14권2호
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• pp.93-103
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• 2005

This paper presents characteristics of a virtual human's navigation using a limited perception-based mapping. Previous approaches to virtual human navigation have used an omniscient perception requiring full layout of a virtual environment in advance. However, these approaches have a limitation on being a fundamental solution for a human-likeness of a virtual human, because behaviors of humans are basically based on their limited perception instead of omniscient perception. In this paper, we integrated Hill's mapping algorithm with a virtual human to experiment virtual human's navigation with the limited perception. This approach does not require full layout of the virtual environment, 360-degree's field of view, and vision through walls. In addition to static objects such as buildings, we consider enemy emergence that can affect an virtual human's navigation. The enemy emergence is used as the variable on the experiment of this present research. As the number of enemies varies, the changes in arrival rate and time taken to reach the goal position were observed. The virtual human navigates by two conditions. One is to take the shortest path to the goal position, and the other is to avoid enemies when the virtual human encounters them. The acquired result indicates that the virtual human's navigation corresponds to a human cognitive process, and thus this research can be a framework for human-likeness of virtual humans.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2006년도 한국컴퓨터종합학술대회 논문집 Vol.33 No.1 (D)
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• pp.124-126
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• 2006

Mobile Ad hoc networking is an emerging technology and in these days many applications are being developed to run on these networks. In these networks lookup services are very important because all nodes do not have same resources in term of memory and computing power. Nodes need to use different services offered by different servers. Reliable and efficient scheme should be available for lookup services due to limited bandwidth and low computing power of devices in mobile ad hoc networks. Due to mobility and rapid change in network topology, lookup mechanism used in wired network is not appropriate. Service discovery mechanism can be divided into two main categories Centralized and Distributed. Centralized mechanism is not reliable as there is no central node in these networks. Secondly centralized mechanism leads toward single point failure. We can handle the service discovery mechanism by distributing server's information to each node. But this approach is also not appropriate due to limited bandwidth and rapid change in network. In this paper, we present reliable lookup service scheme which is based on distributed mechanism. We are not using replication approach as well due to low bandwidth of wireless networks. In this scheme service discovery mechanism will be handled through different lookup servers. Reliability is the key feature of our proposed scheme.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2011년도 하계학술대회
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• pp.137-140
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• 2011

A precoding strategy is one of the representative interference management techniques in cognitive radio (CR) network which is a typical interference-limited environment. The interference minimization approach to precoding is an appropriate scheme to mitigate the interference efficiently while it may cause the capacity loss of the desired channel. The precoding scheme for the maximal capacity of the desired channel improves the capacity of the desired channel while it increases the interference power and finally causes the capacity loss of the interfered users. Therefore, we propose a precoding scheme which satisfies these two conflicting goals and manages the interference signal in such an interference-limited environment. The proposed scheme consists of two steps. First, the precoder nulls out the largest singular value of the interference channel to mitigate the dominant interference signal based on the interference minimization approach. Second, the transmitter calculates the sum capacities per mode and selects a mode to maximize the sum capacity. In the second step, each mode consists of the right singular vectors corresponding to the singular values except the largest singular value eliminated in the first step. Simulation results show that the proposed precoding scheme not only efficiently mitigate the interference signal, but also has the best performance in terms of the sum capacity in a MIMO-based CR network.

• The Journal of Asian Finance, Economics and Business
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• 제7권9호
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• pp.169-178
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• 2020

In this paper, we provide an overview of financial development in Vietnam. Particularly, a new approach of this study is to measure financial development through improvements in depth, efficiency and access of the banking system and stock market. Further, the study examines the factors significantly affecting financial development in Vietnam. The data are collected in Vietnam, an emerging country with a limited financial development. We employ the Autoregressive Distributed Lag (ARDL) approach, which generates a high reliability and suits data characteristics of emerging countries like Vietnam. We observe that Vietnam's banking system plays a key role in supplying credits to the economy while the nascent stock market at a limited size shows its potential for a considerable growth in the future. We also find the influential determinants of financial development in Vietnam including real estate market (RE), economic growth (EG), consumer price index (CPI), and global financial crisis (GFC). These findings are essential for Vietnamese authorities in providing practical solutions in order to build a sustainable and synchronous financial development. They are also first empirical evidence relating to an overview of financial development in an emerging country, so they are not only valuable to Vietnam but also crucial to other emerging economies.

• Journal of Computing Science and Engineering
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• 제4권2호
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• pp.128-152
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• 2010

With the advance of computer and communication technologies, wireless sensor networks (WSNs) are increasingly used in many aspects of our daily life. However, since the battery lifetime of WSN nodes is restricted, the WSN lifetime is also limited. Therefore, it is crucial to determine this limited lifetime in advance for preventing service interruptions in critical applications. This paper proposes a feasible static analysis approach to estimating the worstcase lifetime of a WSN. Assuming known routes with a given sensor network topology and SMAC as the underlying MAC protocol, we statically estimate the lifetime of each sensor node with a fixed initial energy budget. These estimations are then compared with the results obtained through simulation which run with the same energy budget on each node. Experimental results of our research on TinyOS applications indicate that our approach can safely and accurately estimate worst-case lifetime of the WSN. To the best of our knowledge, our work is the first one to estimate the worst-case lifetime of WSNs through a static analysis method.