• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.12
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• pp.65-72
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• 2008

This paper proposes a new dual-loop digital PLL(DPLL) using seamless frequency tracking methods. The dual-loop construction, which is composed of the coarse and fine loop for fast locking time and a switching noise suppression, is used successive approximation register technique and TDC. The proposed DPLL in order to compensate the quality of jitter which follows long-term of input frequency is newly added cord conversion frequency tracking method. Also, this DPLL has VCO circuitry consisting of digitally controlled V-I converter and current-control oscillator (CCO) for robust jitter characteristics and wide lock range. The chip is fabricated with Dongbu HiTek $0.18-{\mu}m$ CMOS technology. Its operation range has the wide operation range of 0.4-2GHz and the area of $0.18mm^2$. It shows the peak-to-peak period jitter of 2 psec under no power noise and the power dissipation of 18mW at 2GHz through HSPICE simulation.

• Journal of the Korean Arthroscopy Society
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• v.6 no.1
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• pp.43-48
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• 2002

Purpose : We evaluated the results of the arthroscopic treatment of nine cases of synovial chondromatosis in the knee joints. Materials and Methods : From June 1989 to September 1999, eight patients nine cases with synovial chondromatosis involving knee joints underwent arthroscopic total synovectomy and removal of loose bodies. There were 6 females and 2 males. The average age at surgery was 44.1 years(range, 20-57 years). The average follow-up period was 5.9 years (range, 2.5-7.3 years). All cases had pain and swelling and two cases had locking preoperatively. Flexion contracture was found in three cases. Results : Pathologic finding revealed Milgram I in one case, Milgram II in six cases and Milgram III in two cases. There were six cases of generalized synovial hypertrophy and one case of localized type. All patients had symptomatic relief by arthroscopic total synovectomy and loose body removal. Second arthoroscopic surgery was performed in one patient due to recurred lesions 11 months after the primary surgery. Conclusion : Clinical results of the synovial chondromatosis with arthroscopic total synovectomy and loose body removal were satisfactory. Arthroscopic total synovectomy was also effective for the recurred case.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.210-218
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• 2018

In order to generate meshes automatically for finite element analysis of complex structures such as aircraft, a large number of triangular elements are typically created. However, triangular elements are less accurate than rectangular elements, so it is difficult to obtain a reliable solution. This problem can be improved through the meshfree method using the back cell integration. However, this method also causes some problems such as over-use of the integration points and inefficiency of the integral domain. In order to improve these problems, a method of performing integration by setting the integral area based on a node basis has been proposed, but in the case of incompressible material problems, the numerical accuracy deteriorates due to the vibration phenomenon of the solution. Therefore, in this paper, the modified meshfree method is proposed which sets the integral domain as an element domain instead of the nodal domain, and the proposed method improves the numerical instability caused by the conventional meshfree method without decreasing the accuracy regardles of the shape of integral domain. The effectiveness of the modified meshfree method is verified by using 2-D examples.

• Journal of KIISE:Databases
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• v.29 no.3
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• pp.230-245
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• 2002

Database systems for real-time applications must satisfy timing constraints associated with transactions. Typically, a timing constraint is expressed in the form of a deadline and is represented as a priority to be used by schedulers. Recently, security has become another important issue in many real-time applications. In many systems, sensitive information is shared by multiple users with different levees of security clearance. As more advanced database systems are being used in applications that need to support timeliness while managing sensitive information, there is an urgent need to develop concurrency control protocols in transaction management that satisfy both timing and security requirements. In this paper, we propose two concurrence control protocols that ensure both security and real-time requirements. The proposed protocols are primarily based on multiversion locking. However, in order to satisfy timing constraint and security requirements, a new method, called the FREEZE, is proposed. In addition, we show that our protocols work correctly and they provide a higher degree of concurrency than existing multiversion protocols. We Present several examples to illustrate the behavior of our protocols, along with performance comparisons with other protocols. The simulation results show that the proposed protocols can achieve significant performance improvement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.614-621
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• 2019

A generalized laminated composite beam element is presented for the flexural and buckling analysis of laminated composite beams with double and single symmetric cross-sections. Based on shear-deformable beam theory, the present beam model accounts for transverse shear and warping deformations, as well as all coupling terms caused by material anisotropy. The plane stress and plane strain assumptions were used along with the cross-sectional stiffness coefficients obtained from the analytical technique for different cross-sections. Two types of one-dimensional beam elements with seven degrees-of-freedom per node, including warping deformation, i.e., three-node and four-node elements, are proposed to predict the flexural behavior of symmetric or anti-symmetric laminated beams. To alleviate the shear-locking problem, a reduced integration scheme was employed in this study. The buckling load of laminated composite beams under axial compression was then calculated using the derived geometric block stiffness. To demonstrate the accuracy and efficiency of the proposed beam elements, the results based on three-node beam element were compared with those of other researchers and ABAQUS finite elements. The effects of coupling and shear deformation, support conditions, load forms, span-to-height ratio, lamination architecture on the flexural response, and buckling load of composite beams were investigated. The convergence of two different beam elements was also performed.

• Journal of Korean Orthopaedic Sports Medicine
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• v.6 no.2
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• pp.92-98
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• 2007

Purpose: We evaluated the clinical results of arthroscopic ACL reconstruction using quadrupled hamstring tendon with tibial remnant-preserving technique. Materials and Methods: Thirty-five cases were evaluated from Feb, 2003 to May, 2006. The average interval from injury to surgery was $2.6{\pm}1.6$ months. The cause of injury was mostly sports-related trauma. The average follow-up period was 17 months. Tibial remnant was preserved as much as possible and caution was taken not to damage the remnant during ACL reconstruction. Postoperative rehabilitation was the same as the usual rehabilitation method after ACL reconstruction, except for delaying motion for 2 weeks with an extension locking brace. Clinical evaluation was performed using ROM; Lachman test; pivot-shift test; anterior displacement measurement using KT-2000 arthrometer; Lysholm score and proprioception measured by single limb standing test. Results: There was no limitation of knee motion without contracture. The Lachman test and pivot-shift test were both negative. The side-to-side difference of anterior displacement measured using KT-2000 arthrometer was improved from 6.7 mm to 2.2 mm. The average Lysholm score improved from 81 to 96. The single limb standing test for proprioceptive evaluation showed no significant difference from a normal leg. Conclusion: ACL reconstruction with tibial remnant-preserving technique can preserve mechanoreceptors with prorioception and expect good functional recovery.

• Clinics in Shoulder and Elbow
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• v.16 no.2
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• pp.130-134
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• 2013

A painful pseudoarthrosis will develop due to a delay in diagnosis and treatment, and surgical care is required. Treatment of pseudoarthrosis is really difficult because the acromion is a thin flat bone that is difficult to be fixed firmly. A 52-year-old woman with multiple trauma had an acromial fracture that was not detected until it had caused pain after ambulation. Open reduction and internal fixation with a variable angle locking compression plate for distal radius and autogenous iliac bone graft were performed. At nine months after the operation, there was partial tear in the supraspinatus tendon, and arthroscopic repair of the supraspinatus tendon was performed. At nine months after the operation, radiographs showed a complete union. At three months after tendon repair, the patient had excellent function of the shoulder. We have reported a case of a successful treatment of nonunion and pseudoarthrosis of acromial fracture that is difficult to be fixed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5534-5540
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• 2015

This In the railway signaling system, applications of axle counter in addition to track circuit goes on increasing for detecting train position. Consequently, this paper compares sensor methods of axle counter with between geo-magnetism method and proximity sensor method. And it presents differences and results, to improve reliabilities of train detection and axle counting. Also, this article presents an applied result which is based on field experience, with regard to installation, considering attachment condition of sensor part for accurate axle counting. This study acquires expandability that is able to perform not only axle counting function but also various other functions (direction detection of train, speed detection of train, and so on). It was a result of a change of design in order to judge phase difference of sensors, to improve reliability of axle counting. Furthermore, it does not subordinate to characteristics (type, weight of train). And it is confirmed that the omission of axle counting was not occurred in 350km/h. This was the result of Lab test after the construction of transfer equipment of trial axle and Test Bed for axle counting. Both of them are self-productions. Through this, it prepares foundation which is able to apply not only to train detection but also to speed of passing trains, formation number of trains, detector locking condition - when the train passes the section of switch point, and level crossing devices. Furthermore, it would be judged to contribute safety train operation if proximity sensor method applies to the whole railway signaling system from now on.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.6
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• pp.623-634
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• 2003

In this paper, we propose a collaborative multimedia authoring system. Our authoring system represents a multimedia presentation in a 3D coordinate system. One axis represents the traditional timeline information (T-zone), and the other two axes represent spatial coordinates (XY-zone). Our system represents a visual media objects as a 3D parallelepipeds and audio media objects as cylinders. This interface allows for simultaneous authoring and manipulation of both the temporal and the spatial aspects of a presentation. Using our system, users can design multimedia presentations collaboratively in the unified spatio-temporal space while freely traversing the spatial domain and the temporal domain without changing the context of authoring. In addition, we suggest an efficient mechanism of concurrency control for shared objects generated by our collaborative writing system. The mechanism is mainly based on the user awareness, the multiple versions, and the access permission of shared objects. Our concurrency control mechanism is designed to keep data consistency by minimizing the collision due to the delay or the failure of network communication and to allow maximum responsiveness for users using optimistic concurrency control. Also, the mechanism maximize the responsiveness by refining the locking granularity and applying different concurrency control mechanisms to each.

• Journal of Oral Medicine and Pain
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• v.38 no.2
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• pp.175-185
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• 2013

Objective : Condyle hypoplasia in temporomandibular joint(TMJ) is often observed in several radiographic views. Mandibular Condyle hypoplasia is frequently confused with osteoarthritis with bony changes in TMJ. This paper investigated clinical characteristics of mandibular condyle hypoplasia as compared with TMJ osteoarthritis. Material and method : 276 patients with TMD were taken clinical and radiological examination and were divided into study group, 189 patients diagnosed with mandibular condyle hypoplasia, and control group, 87 patients diagnosed with TMJ osteoarthritis. And clinical features(Onset, Overjet, Overbite, Noise, Locking, NAS of noise, LOM, pain, MCO, and site of diagnosis and pain)of the two groups were compared. Results : 1. Mandibular condyle hypoplasia and TMJ osteoarthritis were similar in many of the clinical features. 2. Mandibular condyle hypoplasia concordance rates of the radiographic diagnosis site and the pain site was significantly lower than TMJ osteoarthritis. 3. Bilateral mandibular condyle hypoplasia group had more occlusal discomfort, and clenching habits than unilateral mandibular condyle hypoplasia group. 4. Unilateral mandibular condyle hypoplasia group had more unilateral chewing habits and LOM than unilateral TMJ osteoarthritis group. Unilateral TMJ osteoarthritis group had more morning stiffness and higher concordance rates of the radiographic diagnosis site and the click sound site than unilateral mandibular condyle hypoplasia group. 5. Bilateral mandibular condyle hypoplasia group had more usual headaches and overjet than bilateral TMJ osteoarthritis group. Conclusion : Mandibular condyle hypoplasia has somewhat distinguishing clinical characteristics as compared with TMJ osteoarthritis.