• The Journal of the Korean bone and joint tumor society
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• v.10 no.2
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• pp.134-137
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• 2004

The osteochondroma is the most common benign bone tumor which arise in the metaphyseal or metaphysiodiaphyseal portion of long bone. Osteochondroma is rare in hand and extremely rare in the intraarticular location of the hand. We report a case of intraarticular osteochondroma which occurred at the third metacarpal head of the hand in a 53 year old female patient. The size of the excised mass was $10{\times}8{\times}5$ mm with definite cartilage cap.

• The Journal of the Korean bone and joint tumor society
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• v.5 no.1
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• pp.17-22
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• 1999

Over 60 cases were enlisted, but only 31 cases among 24 patients were eligible with a minimum follow-up of 1 year and complete medical documents with imaging data. There were 18 boys and 6 girls, and 7 patients had bilateral lesions. The age of the patients ranged from 2 to 20 years(mean:10.5 years). At their first visit, most lesions had a highly characteristic location and radiographic appearance of radiolucent lesion(s) ranging from 1 to 3cm, except for one case of 5.5 cm in the posteromedial comer of distal femoral metaphysis. The margins were generally well-defined, although some were ill-defined. After reviewing our cases from the viewpoint of clinical course and radiographic patterns, we divided these lesions into two types. Type I is the osteolytic lesion excavated into the posteromedial aspect of the distal femur without cortical defect; and type II is the buldged out lesion of the femur with cortical irregularity into the surrounding soft tissues. Both types have distinctive clinical courses. Type I lesions were easy to make a definite diagnosis with plain radiographs alone, but in type II, it was sometimes very difficult to differentiate it from malignant tumors or chronic localized osteomyelitis. For this lesion, Gd-enhanced MRI was the most effective method for differential diagnosis. In this study, biopsy was not necessary to confirm the diagnosis. Clinical symptoms of type I were very minor or even absent. Many of them were accidentally found after minor trauma around the knee joint. Clinical symptoms disappeared far earlier than radiographical lesions. No treatment such as restriction of activity or drugs was necessary. For type II, the clinical symptoms were more accentuated and lasted longer, and it was necessary to restrict the activity for a certain period in many cases. However, all were self-limited.

• The Korean Journal of Pain
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• v.13 no.2
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• pp.242-246
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• 2000

Radiofrequency medial branch neurotomy is an effective way of controlling pain in the posterior compartment of the spine such as the facet joint, and the interspinous ligament. However, it is difficult to determine the exact location of the medial branch. Up until now we have relied on sensory response provoked by 50 Hz stimulation. The responses elicited using this method are quite subjective and can originate from sources other than the medial branch such as the periosteum, the intermediate or lateral branch. We need a confirmed indicator to locate the medial branch reliably. We applied 2 Hz stimulation under 0.4 volts to locate the medial branch and elicited a motor response. Twitching of multifidus and muscles around the SI joint was observed. The observation of these muscles provides a much more reliable method for confirmation of the medial branch. We have treated 45 chronic nonspecific low back pain patients using radiofrequency medial branch neurotomy with this method of confirming the medial branch.

• Journal of Ocean Engineering and Technology
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• v.6 no.2
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• pp.21-34
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• 1992

The behavior of fatigue crack growth in the single spot welded joint of zinc galvanized steel sheets was studied experimentally and analytically based on fracture mechanics. Axial tension fatigue tests were carried out with the BSxGAB specimen that the bare plane(GAB) of monogalvanized steel sheet was spot welded to the double thickness bare steel sheet(BS), and with the GAxGAB specimen that the galvanized plane (GA) was spot welded to the equal thickness bare plane (GAB) 1. The relation between maximum stress intensity factor, K sub(max) and the number of cycles to failure, N sub(f) has shown a linear relation on log-log plot in the spot weld of the zinc galvanized steel sheet. 2. The fatigue strength of BSxGAB specimens is about 23% higher than that of GAxGAB specimens at the fatigue strength of $1\times10^6$ cycles. And the fatigue life of BSxGAB specimens at the same load range increases 6~9 times higher than that of GAxGAB specimens. 3. The general tendency at the angle of bending($\theta$) in an applied load has changed rapidly at the initial 20% of its life. After then, it has changed slowly. The change at the angle of bending has increased linearly as the load range increases. 4. It has shown a linear relation between the location ratio of initiation ${\gamma}$ and fatigue life $N_f$ on the semi-log graph paper. Here $\gamma$ means that the crack distance between main crack and sub-crack, 2L is divided by the nugget diameter, 2r. $\gamma=a{\cdot}log N_f+n$ (where a and n are material constant.)

• Journal of Korea Multimedia Society
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• v.11 no.11
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• pp.1575-1591
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• 2008

In this paper, we propose a new method detecting foot motion capture in order to overlap in realtime foot's 3D virtual model from stereo cameras. In order to overlap foot's virtual model at the same position of the foot, a process of the foot's joint detection to regularly track the foot's joint motion is necessary, and accurate register both foot's virtual model and user's foot in complicated motion is most important problem in this technology. In this paper, we propose a dynamic registration using two types of marker groups. A plane information of the ground handles the relationship between foot's virtual model and user's foot and obtains foot's pose and location. Foot's rotation is predicted by two attached marker groups according to instep of center framework. Consequently, we had implemented our proposed system and estimated the accuracy of the proposed method using various experiments.

• Imaging Science in Dentistry
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• v.36 no.4
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• pp.199-206
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• 2006

Purpose: The purpose of this study was to evaluate comparison of static MRI and pseudo-dynamic (cine) MRI in temporomandibular joint (TMJ) disorder patients. Materials and Methods: In this investigation, 33 patients with TMJ disorders were examined using both conventional static MRI and pseudo-dynamic MRI. Multiple spoiled gradient recalled acquisition in the steady state (SPGR) images were obtained when mouth opened and closed. Proton density weighted images were obtained at the closed and open mouth position in static MRI. Two oral and maxillofacial radiologists evaluated location of the articular disk, movement of condyle and bony change respectively and the posterior boundary of articular disk was obtained. Results: No statistically significant difference was found in the observation of articular disk position, mandibular condylar movement and posterior boundary of articular disk using static MRI and pseudo-dynamic MRI (P<0.05). Statistically significant difference was noted in bony changes of condyle using static MRI and pseudo-dynamic MRI (P<0.05). Conclusion: This study showed that pseudo-dynamic MRI didn't make a difference in diagnosing internal derangement of TMJ in comparison with static MRI. But it was considered as an additional method to be supplemented in observing bony change.

• The Journal of the Korean bone and joint tumor society
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• v.9 no.2
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• pp.212-216
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• 2003

A Common peroneal nerve palsy caused by ganglionic cyst is very rare condition but well recognised entities. There have been three previous reports describing the magnetic resonance image (MRI) findings of peroneal nerve entrapment due to a ganglionic cyst. Ultrasonography, MRI, and electromyography (EMG), nerve conduction velocity (NCV), and microscopic examination were taken for diagnosis. A tubular structure near the fibular neck extending longitudinally over several slices with an inferior extension towards the superior tibiofibular joint with high T2 signal intensity was characteristic. The peroneal nerve was exposed and the ganglionic cyst was excised. The nerve was paralysed immediately after operation, but at 4 month after operation, started recovery of the function gradually and has recovered completely at 7 month. MRI is helpful to detect the extent, location, and origin of the cyst. Meticulous surgical excision can provide favorable result.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.2
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• pp.76-83
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• 1996

We have developed the unconventional robot arm which is composed of the two main parts, one is a ball screw and the other is a robot arm. The dynamic systems of the robot arm and ball screw are unstable systems coupled with each other. The ball screw mechanism is unstable system but controllable system. The robot arm's dynamics is quasi stable system when ball screw's angular position is zero, else, unstable system. Our system has the duality between stability and controllability at the view point of control. This duality causes difficulty to control of the robot arm using normal control law. We have investigated the location of the characteristic roots of the dynamic equation. And we have found out that the best condition for the control of the arm is quasi stable state. In this paper, we have proposed multiple control laws which are consist of three components to guarantee the stability and controllability simultaneously. The computer simulations were carried out based on VSC about the angular position control of the robot arm, and it is confirmed that the good performances could be obtained by using new controller.

• Journal of the Korean Arthroscopy Society
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• v.15 no.2
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• pp.121-124
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• 2011

Hill-Sachs lesion is the most common lesion in shoulder dislocation patient and it represented by postero-lateral bony defect of humerus. The lesion could be found in patients who dislocate shoulder joint first time, and it is reported that Hill-Sachs lesion proportionally increases as dislocation does. The location and presence of Hill-Sachs lesion play significant roles in shoulder instability. Authors experienced a double Hill-Sachs lesion in a recurrent anterior shoulder dislocation patient, and thereby report the case with a review of the literature.

• Journal of Korean Society of Steel Construction
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• v.14 no.2
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• pp.385-394
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• 2002

Currently, high strength steel is not used for steel bridges in Korea, except for the SM570 high strength steel in very isolated cases. The study aimed to promote the active adaptation of high strength steel for long-span steel bridges. Thus, the fatigue behavior of SM570 and POSTEN80 high strength steel was investigated. For the experimental study, the butt welded joints samples were manufactured. Likewise, regular amplitude tensile fatigue tests were conducted. Test results, e.g., location of fatigue cracks and their propagation were compared with the findings of other researchers. After analyzing the effects of fatigue strength, e.g., static tensile strength and plate thickness of base metal, basic data for fatigue design criteria of SM570 and POSTEN80 high strength steel were presented.