• Steel and Composite Structures
• /
• v.50 no.2
• /
• pp.149-158
• /
• 2024

Considering that different boundary conditions can have an important impact on structural vibration characteristics. In this paper, the nonlinear forced vibration behavior of functionally graded material (FGM) doubly curved shells with initial geometric imperfections under different boundary conditions is studied. Considering initial geometric imperfections and von Karman geometric nonlinearity, the nonlinear governing equations of FGM doubly curved shells are derived using Reissner's first order shear deformation (FOSD) theory. Three different boundary conditions of four edges simply supported (SSSS), four edges clamped (CCCC), clamped-clamped-simply-simply (CCSS) were studied, and a system of nonlinear ordinary differential equations was obtained with the help of Galerkin principle. The nonlinear forced vibration response of the FGM doubly curved shell is obtained by using the modified Lindstedt Poincare (MLP) method. The accuracy of this method was verified by comparing it with published literature. Finally, the effects of curvature ratio, power law index, void coefficient, prestress, and initial geometric imperfections on the resonance of FGM doubly curved shells under different boundary conditions are fully discussed. The relevant research results can provide certain guidance for the design and application of doubly curved shell.

• Imaging Science in Dentistry
• /
• v.34 no.1
• /
• pp.49-54
• /
• 2004

Primary intraosseous carcinoma (PIOC) is a rare odontogenic carcinoma defined as a squamous cell carcinoma arising within a jaw having no initial connection with the oral mucosa, and presumably developing from residues of the odontogenic epithelium. A 56-year-old patient who complained of delayed healing after extraction of upper left central incisor visited our department. The conventional radiographs showed a bony destructive lesion with ill-defined margin and moth-eaten appearance. On the computed tomographic images, the lesion perforated the labial cortex of alveloar bone, elevated the left nasal floor superiorly, and perforated partially both nasal floor. The magnetic resonance images showed low signal intensity at T2 and Tl weighted images at the area and adjacent soft tissue. Histologically, there were irregular epithelial islands with cell atypia, nuclear hyperchromatism, pleomorphism, atypical mitosis. The final diagnosis was PIOC.

• Proceedings of the KIEE Conference
• /
• 1996.07a
• /
• pp.486-488
• /
• 1996

A dc-dc converter which transfers l2-48W of power(regulated output voltage 24V) across a large, variable air gap(1-2cm) has been designed. This converter employs double resonance to compensate the large leakage inductance of the primary and secondary of the transcutaneous transformer. To maximize the effect of resonance, a constant frequency, duty cycle control method is used. The duty cycle control presents advantages over a frequency control in terms of increase in dc voltage gain and reduction of the primary current. The analysis and design procedure for the proposed scheme is presented and the performance result is simulated and verified experimentally.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.12
• /
• pp.129-135
• /
• 1996

This paper presents the effectiveness of the dynamic vibration absorber consisting of a single mass, coil springs and oil damper on the resonance freauency ratio and amplitude ratio for damped linear systems, that is, primary vibration system with damping. The effects of the dynamic vibration absorber are investigated numerically and experimentally for values of mass ratio, natural frequency ratio, and damping ratio. The experimental results show good agreement with calculated ones. As a result, the characteristics shown by the present work are useful in optimal tuning the dynamic vibration absorber in practice.

• Investigative Magnetic Resonance Imaging
• /
• v.24 no.2
• /
• pp.90-94
• /
• 2020

Synchronous primary cancers in the liver and gallbladder have been rarely reported. We report a case of synchronous cancers of hepatic angiosarcoma and gallbladder adenocarcinoma, mimicking gallbladder cancer with hepatic invasion. Additionally, the clinical implications, the radiologic features, and the diagnostic difficulties are further discussed.

• Structural Engineering and Mechanics
• /
• v.36 no.2
• /
• pp.149-163
• /
• 2010

Transverse vibrations of axially moving beams with multiple concentrated masses have been investigated. It is assumed that the beam is of Euler-Bernoulli type, and both ends of it have simply supports. Concentrated masses are equally distributed on the beam. This system is formulated mathematically and then sought to find out approximately solutions of the problem. Method of multiple scales has been used. It is assumed that axial velocity of the beam is harmonically varying around a mean-constant velocity. In case of primary resonance, an analytical solution is derived. Then, the effects of both magnitude and number of the concentrated masses on nonlinear vibrations are investigated numerically in detail.

• Journal of Korean Neurosurgical Society
• /
• v.40 no.3
• /
• pp.199-201
• /
• 2006

An organizing hematoma with tumor-like presentation in association with a chronic subdural hematoma[CSDH] has not been reported. Most reported cases of an intracranial mass in association with a CSDH have been associated with primary or metastatic neoplasm. A 72-year-old man presenting with an intracranial contrast-enhancing mass in association with a CSDH in magnetic resonance images is reported. Operative exploration revealed the mass to be an organized hematoma adjoining cortical draining veins between the outer and inner membranes of a chronic subdural hematoma. This report adds another important differential diagnosis to various primary and metastatic neoplasms that have been reported in the literature when encountering an intracranial mass in association with a CSDH. Neurosurgeons should be aware of the possibility and, It necessary, should apply more diagnostic modalities than magnetic resonance images before deciding management plans.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.11 no.4
• /
• pp.65-70
• /
• 2001

An investigation into asymmetric vibrations of a clamped circular place under a harmonic excitation is made. We examine a primary resonance. in which the frequency of excitation is near the natural frequency of an asymmetric mode of the plate. We found not only a response haying the form of standing wave but also one having the form of traveling wave, which was not observed by Sridhar, Mook and ${Nayfeh}^{(1)}$

• Investigative Magnetic Resonance Imaging
• /
• v.20 no.4
• /
• pp.264-268
• /
• 2016

Benign fibrous histiocytoma (BFH) is a rare benign primary skeletal tumor that occurs commonly in the long bones, spine and pelvis. BFH constitutes a diagnostic challenge because it shares clinical background, radiological characteristics, and histological features with other fibrous lesions such as non-ossifying fibroma, giant cell tumor. We present a case of BFH with cystic change that occurred in the distal femur. We did not identify any case of BFH with cystic change involving the majority of the lesion that occurred in the metaepiphysis of the long bone.

• Investigative Magnetic Resonance Imaging
• /
• v.21 no.2
• /
• pp.119-124
• /
• 2017

Chromophobe renal cell carcinoma (RCC) is an uncommon subtype of RCC having a better prognosis than clear cell RCC. Although there are several reports of seeding metastasis of RCC after biopsy, seeding metastasis of chromophobe RCC after surgical resection has seldom been reported. Here, we describe a case of multiple seeding metastases in the abdomen and pelvis 78 months after robot-assisted laparoscopic partial nephrectomy, without prior history of biopsy for chromophobe RCC in the right kidney. As magnetic resonance imaging (MRI) of the pelvic mass showed a similar appearance to the primary renal mass and displayed separate margins with the rectum and prostate gland, we were able to make a diagnosis before pathologic confirmation.