[en] The hyper-elastic material has been used gradually and its range was extended all over the industry. The performance prediction of hyper-elastic material was required not only experimental methods but also numerical methods. In this study, we presented the process how to use numerical method for hyper-elastic material and applied it to seat-ring of butterfly valve. The finite element analysis was executed to evaluate the mechanical characteristics of hyper-elastic material. And the optimum model considered conditions and features. According to that model, the load conditions were obtained by using CFD analysis

[en] Myelography and CT scan appear to be the essential radiologic procedures for the investigation of spinal cord tumors. CT scans can be performed either with no additional procedure (plain CT) or associated with IV or intrathecal injection of contrast medium. As myelography gives a global view we prefer to start with this procedure; it is extremely helpful in proving a guide to adequate subsequent CT myelography. Authors reviewed retrospectively CT myelography findings of 41 pathologically proven spinal cord tumors during a recent 5 year period. The results were follows: 1. CT scan well demonstrated bone destruction, extent of tumors into epidural space or paravertebral soft tissues and also tissue composition of tumors such as fat and calcification. 2. There were some different CT findings between neurilemmoma and meningioma. In 9 cases of meningioma, calcification (39) and irregular margin (4/9) were shown but bone change was not sen. In 16 cases of neurilemmoma, relatively smooth margin tumor (11/12*) and bone change (4/16) were shown but calcification was not seen. Authors excluded neurilemmomas in lumbosacral area (4/16) because tumors in this area shown poor delineation of surface margin due to crowing of cuada equina

[en] Von Recklinghausen's nuerofilbromatosis is a kind of neurocutaneous syndrome characterized by skin, nervous system, neuromusculoskeletal manifestations. Most central and peripheral nervous neoplastic lesions in neurofibromatosis are benign but have a significant potential for malignant transformation such as neurofibrosarcoma, neurogenic sarcoma, malignant schwannoma. And it is relatively common disorder but malignant change with radiologic findings has been reported rarely in Korea. Recently we experienced three cases of malignant degeneration in neurofibromatosis and confirmed by pathology. So we report the cases with review including radiologic findings

[en] The first role of radiologist concerning with tumors or tumor like lesions of bone is to differentiate natures of their benignancy or malignancy. It is true that there were much of difficulties to distinguish osteomyelitis from malignant lesions radiographically. Although there is no single periosteal reaction that is unique for any disease process, we had confirmed a certain periosteal reaction, that is, a lamellar nodular pattern, might aid to differentiate osteomyelitis from malignant bone tumor. The thirty patients of acute osteomyelitis in whom the follow-up studies were possible, eighteen patients with osteosarcoma and five patients with Ewing's sarcoma were retrospectively evaluated : periosteal reactions in acute osteomyelitis (30 cases) undergo changes in their appearance that can be categorized : thin solid (18 cases), Codman's triangle (2 cases), no periosteal reaction (10 cases) in early phase ; lamellated (7 cases) and lamellar nodular patterns (7 cases) in the course of the disease with pronounced reactive osteoblastic change in the medullary cavity ; in chronic forms (14 cases), cortical thickening (11 cases), cortical thickening with involucrum (2 cases) and cortical thickening with sequestrum (1 case) were noted. In 18 cases of osteosarcoma were included : thin solid (1 case), lamellated (2 cases), sunburst (5 cases), and Codman's triangle (2 cases) ; combined forms (5 cases) i.e., thin solid and lamellated (1 case), lamellated and sunburst (2 cases), sunburst and Codman's triangle (1 case), lamellated, sunburst and Codman's triangle (1 case) ; and no periosteal reaction (3 cases). 5 cases of Ewing's sarcoma showed sunburst (1 case), interrupted periosteal reaction (1 case), and no periosteal reaction (3 cases). It is advised when a lamellar nodular periosteal reaction appeared with reactive osteoblastic reaction in the host bone, even though their looking might be suggested to aggressiveness of the lesion, it should be considered osteomyelitis rather than malignant bone tumors such as osteosarcoma or Ewing's sarcoma

[en] Fifteen scalp masses consisting of five benign and ten malignant tumors were studied with ultrasound to evaluate its diagnostic role in scalp masses. Benign mass showed homogeneous echo pattern with smooth margin, Hand-Schuller-Christian disease(n=1) demonstrated solid mass in the diploic space eroding the outer table. The most of malignant tumors(9 of 10 cases) showed irregular margin, inhomogeneous echotexture, bone destruction, and intracranial extension. Dermatofibrosarcoma protuberans(n=1) revaled well defined hypoechoic solid mass with internal linear echoes. Ultrasonography considered as an initial noninvasive imaging modality for the evaluation of scalp masses

[en] The purpose of this study is to examine the change of full width half maximum(FWHM) and residual stress during fatigue process in S45C Steel, by X-ray diffraction. For S45C Steel, the relationship between the change in fatigue damage of the specimen and the FWHM, and residual stress of X-ray diffraction profiles during the fatigue processes has been investigated. The FWHM decreases in the early period of fatigue cycle. The change of FWHM is associated with cyclic work hardening. The change of the FWHM is not significant in 10∼20% of ratio of fatigue life. The residual stress is changed with fatigue cycle increasing during the fatigue pro process