• Structural Engineering and Mechanics
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• 제91권5호
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• pp.503-516
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• 2024

The present research examines the primary resonance (PR) behaviors of oblique stiffened multilayer functionally graded (OSMFG) shallow shells featuring an FG porous (FGP) core under an external excitation. The research considers two distinct types of FGP cores: one characterized by uniform porosity distribution (UPD) and the other by non-uniform porosity distribution (NPD) along the thickness direction. Furthermore, the study explores two types of shallow shells: one with external oblique stiffeners and one with internal oblique stiffeners, which might have angles that are similar or different from each other. Using the stress function alongside the first-order shear deformation theory (FSDT), the research establishes a nonlinear model for OSMFG shallow shells. The strain-displacement relationships are obtained utilizing FSDT and von-Kármán's geometric assumptions. The Galerkin approach is utilized to discretize the nonlinear governing equations, allowing for the analysis of stiffeners at varied angles. To validate the obtained results, a comparison is made not only with the findings of previous research but also with the response of PR obtained theoretically with the method of multiple scales, using the P-T method. Renowned for its superior accuracy and reliability, the P-T method is deemed an apt selection within this framework. Additionally, the study investigates how differences in material characteristics and stiffener angles affect the system's PR behaviors. The results of this study can be used as standards by engineers and researchers working in this area, and they can offer important information for the design and evaluation of the shell systems under consideration.

• 대한소아치과학회지
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• 제38권4호
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• pp.391-398
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• 2011

저위교합(infraocclusion)은 혼합치열기에 유구치에서 호발하며, 이것은 대부분 이환된 치아의 유착에 의해서 발생하는 것으로 여겨지고 있다. 유착된 저위교합 유구치의 치료 방법은 크게 치아의 보존 및 관찰, 수복, 발거로 나눌 수 있다. 계승치가 존재하고 경도의 저위교합을 가진 유구치의 경우 자연탈락을 기대할 수 있으나, 계승치가 결손되어 있고 저위교합도 점차 진행될 경우 이환된 치아의 발거가 필요할 수 있다. 특히 유착으로 인한 수직적인 치조골 소실이 염려될 경우, 추후 보철치료를 위해 환아의 최대성장기 이전에 유착치의 발거를 시행하여야 한다. 본 증례에서는 만 6세의 다발성 유착 유구치 및 저위교합과 계승치 결손을 보이는 환자에서 인접부의 성장에 따른 치조골의 수직적 결손이 심화되는 것을 막고 정상적인 치조골 성장을 도모하기 위해 최대성장기 이전에 유착치를 발거 후, 장기간에 걸쳐 추적 관찰하였기에 보고하는 바이다.

• Journal of Chest Surgery
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• 제46권6호
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• pp.482-485
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• 2013

Plasmacytoma is a plasma cell neoplasm that locally infiltrates a bone or spreads to extramedullary areas. A new World Health Organization criterion defines solitary plasmacytoma of bone as a localized bone tumor consisting of plasma cells identical to those seen in plasma cell myeloma, which is manifested as a solitary osteolytic lesion in a radiological evaluation. Primary tumors of the sternum are generally malignant, and solitary plasmacytomas of the sternum are very rare tumors. We present herein the case of a patient who had a primary sternal tumor with solitary plasmacytoma and no evidence of multiple myeloma.

• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.99-103
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• 2010

Motivated by recent works on spectrum-sharing systems, this paper investigates the effects of transmit diversity on the peak interference power limited cognitive radio(CR) networks. In particular, we derive the ergodic and outage capacities of a spectrum-sharing system with multiple transmit-antennas. To derive the capacities, peak interference power constraint is imposed to protect the primary receiver. In a CR transmitter and receiver pair with multiple antennas at the transmitter side, the allowable transmit power is distributed over the transmit-antennas to achieve transmit diversity at the receiver. We investigate the effect of this power distribution when a peak interference power constraint is imposed to protect the primary receiver. We show that the transmit diversity does not improve the ergodic capacity compared to the single-antenna system. On the other hand, the transmit diversity significantly improves the outage capacity. For example, two transmit-antennas improve the outage capacity 10 times compared to the single-antenna with a 0 dB interference constraint.

• Journal of Chest Surgery
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• 제51권3호
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• pp.220-222
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• 2018

Myopericytoma is a benign tumor that occurs in soft tissues. Myopericytoma in the lungs is very rare. We report the case of a 63-year-old woman presenting with cavitary masses in the left lung and multiple tiny nodules in both lungs. She underwent surgery, and a histological examination revealed primary pulmonary myopericytoma.

• 디지털산업정보학회논문지
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• 제14권3호
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• pp.77-85
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• 2018

Multi-User Multiple-Input Multiple-Output (MU-MIMO) is the core technology for improving the channel capacity compared to Single-User MIMO (SU-MIMO) by using multiuser gain and spatial diversity. Key problem for the MU-MIMO is the user selection which is the grouping the users optimally. To solve this problem, we adopt Extreme Value Theory (EVT) at the beginning of the proposed algorithm, which defines a primary user set instead of a single user that has maximum channel power according to a predetermined threshold. Each user in the primary set is then paired with all of the users in the system to define user groups. By comparing these user groups, the group that produces a maximum sum rate can be determined. Through computer simulations, we have found that the proposed method outperforms the conventional technique yielding a sum rate that is 0.81 bps/Hz higher when the transmit signal to noise ratio (SNR) is 30 dB and the total number of users is 100.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권3호
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• pp.182-188
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• 2006

Contactless power system is base on power transmission by magnetic force. The transformer loss is large because it separated with the gap. Also the system has unstable factor, since the parameters in the secondary can vary with the system movement. This paper proposes light train power transmission system using contactless transformer with multiple primary winding. To increase the system efficiency and to obtain the stable power transmission to the dynamic load, a resonant inverter is adopted. The proposed system was verified by the simulation using Spice and Maxwell. The designed contactless power transmission system is implemented for 5[kW] class and experimental results are discussed.

• Journal of Chest Surgery
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• 제54권5호
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• pp.422-424
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• 2021

Malignant peripheral nerve sheath tumors are rare sarcomas of the heart. Herein, we report the case of a 24-year-old man who complained of dyspnea, cough, and upper left back pain. He was found to have multiple primary heart tumors obstructing the right superior pulmonary vein in the left atrium, which were diagnosed as malignant peripheral nerve sheath tumors. The patient underwent successful resection of the tumors and immunohistochemistry was utilized for diagnosis.

• Journal of Internet Technology
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• 제20권1호
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• pp.301-313
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• 2019

In this paper, we propose a new MAC protocol for Cognitive Radio (CR)-based IoT networks, called MSMA/CA. We extend the standard CSMA/CA, adopted in IEEE 802.11 WLANs, to the CR networks with the minimal modification since it works well in the real world. We resolve the classical hidden/exposed terminal problems by a variant of RTS/CTS mechanism and further, the hidden primary terminal problem by the mutual spectrum sensing at the transmitter and the receiver. We also modify the backoff process of CSMA/CA to incorporate the blocking of secondary transmitters, with the aim of protecting ongoing primary transmissions from aggressive secondary users. We analyze the throughput and delay of our proposed scheme using the Markov chain model on the backoff procedure, and verify its accuracy by simulations. Simulation results demonstrate that our protocol is suitable for IoT networks since the performance is insensitive to the number of users or devices.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.439-441
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• 2005

A new LLC resonant converter with multiple outputs is proposed for high efficiency and low cost plasma display panel (PDP) power module. In the proposed converter, ZVS turn-on of the primary MOSFETs and ZCS nun-off of the secondary diodes are guaranteed in the overall input voltage and output load range. Moreover, the primary MOSFETs and the secondary diodes have low voltage stresses clamped to input and the output voltage, respectively. Therefore, the proposed converter shows the high efficiency due to the minimized switching and conduction losses. In addition, by employing the transformer, which has the two and more secondary side, the proposed converter can have multiple outputs and they show the great cross-regulation characteristics. As a result, the proposed converter can be implemented with low cost and compact size. The 500W prototype is implemented, which integrates the sustaining and addressing power supplies of PDP power module. The maximum efficiency is 96.8% and the respective output voltages are well regulated. Therefore, the proposed converter is suitable for high efficiency and low cost PDP power module.