• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.3
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• pp.71-78
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• 2011

This paper propose image steganalysis scheme based on independence between parent and child subband on the multi-layer wavelet domain. The proposed method decompose cover and stego images into 12 subbands by applying 3-level Haar UWT(Undecimated Wavelet Transform), analyze statistical independency between parent and child subband. Because this independency is appeared more difference in stego image than in cover image, we can use it as feature to differenciate between cover and stego image. Therefore we extract 72D features by calculation first 3 order statistical moments from joint characteristic function between parent and child subband. Multi-layer perceptron(MLP) is applied as classifier to discriminate between cover and stego image. We test the performance of proposed scheme over various embedding rates by the LSB, SS, BSS embedding method. The proposed scheme outperforms the previous schemes in detection rate to existence of hidden message as well as exactness of discrimination.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.1 no.1
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• pp.49-63
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• 1995

Examination at the spine is dependent on assessment of function. At all spine levels a number of general anatomical considerations hold sway which together dictate the format of the evaluation. Because disc lesions are common and generally responsive to treatment, the examination sets out to differentiate between disc lesions and the other sources of pain as well as establishing the particular treatment that will benefit any given displacement. As elsewhere in the body, displacements give rise to certain characteristic symtoms and signs. First, the history is indicative. Second, any loose fragment in the joint restricts spinal movement in some but not all directions, producing the non-capsular pattern characteristic of internal derangement. Third, a displacement protruding posteriorly interferes with the dura mater ; apart from pain, this adversely affects the dura's normal painless mobility. Fourth, a displacement protruding laterally connects with the appropriate nerve root emerging from the dura mater. Finally, compression of the spinal cord strongly contraindicates manipulation, the primary treatment for cartilaginous displacements.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.2
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• pp.134-140
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• 2010

Synovial condromatosis of the temporomandibular joint (TMJ) is characterized by the presence of loose bodies (joint mices). It can be confused with temporomandibular disorder clinically, and be with chondrosarcoma histologically. The purpose of this clinical report was to review the clinical, radiological, arthroscopic findings, histological feature and the results of surgical treatment of TMJ synovial chondromatosis. Four patients presented with pain of TMJ and limited mouth opening. The dynamic magnetic resonance imaging (MRI) disclosed a characteristic morphologic changes and displacement of the meniscus with limited translation of the condyle head. Bone scans showed progressive resorptive changes with hot-uptake of the radioisotope. The synovial loose bodies in the joint spaces were removed and sent to pathology for diagnosis as the synovial chondromatosis. The follow-up examination with computed tomography (CT) and MRI revealed no evidence of recurrence and good in function until postoperative 18 months. Diagnostically, the distension of the lateral capsule and fluid findings in the joint on the MRI are very suggestive tool for this synovial chondromatosis, but they are not always detected on the preoperative MRI. Arthroscopic approaches are very useful to inspect the joint spaces and to remove the loose bodies without interruption of the whole synovial membranes.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.2
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• pp.136-142
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• 2006

Temporomandibular joint(TMJ) disorders have characteristic clinical findings such as pain, joint sound, and abnormal jaw function. With the rapid progress in TMJ imaging techniques, magnetic resonance imaging(MRI) especially provides the clinician and researcher with the ability to evaluate TMJ disorders(effusion, anterior disk displacement) and the hard and soft tissue of the TMJ. In order to manage the internal derangement of TMJ such as anterior disk displacement, the so-called appliance therapy is commonly used. This technique became the treatment of choice before surgical intervention by many practitioners. The purpose of the present study was to evaluate and determine the efficacy of anterior repositioning splint by means of the change of the position of the disk through pre- and post-treatment MRI. MRI and clinical symptom were carefully recorded in TMJ disorder patients. The relationship between TMJ symptoms such as pain, clicking sound, and disk displacement and effusion in MRI were analyzed. Then, splint therapy was applied for 3 months according to our protocol; at day 1, patients should wear 24 hours, in order to accomodate the splint and then, wearing time is reduced to 12 hours per day for one month. During next 2 months, it is tapered to 8 hours per day according to the evaluation of the clinical symptoms. Post-treatment MRI was obtained after 3 month protocol. This treatment strategy improved the clinical symptoms of TMJ disorder, and effusion and articular disk position showed a significant change. In conclusion, a treatment modality using an anterior repositioning splint therapy is an appropriate method for temporomandibular disorder patients.

• Archives of Reconstructive Microsurgery
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• v.2 no.1
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• pp.53-61
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• 1993

High level, major limb amputation above the wrist and ankle joint has some characteristic problems because of the large muscle mass and poor potential for nerve regeneration. As an adjunct method to reduce warm ischemic time prior to bony stabilization, temporary vascular shunting by simple catheterization has been performed, which has not been associated with any significant complication and has improved on success rate in replantation surgery. The authors have experienced 198 cases replantation of amputated limbs and digits from September, 1983 at the Korea medical center, Guro hospital, of which, 13 cases of successful replantation of amputated limbs by avulsion injury above the wrist and ankle joint level, which is generally considered as contraindication, were followed up for average 4.5 years(minimum 1.5 to maximum 8.4 years) on terms of survival rate, function and appearance. The clinical analysis upon these cases is to be presented with review of references.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.23-30
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• 2012

This paper proposes an improved steganalysis method to detect the existence of secret message. Firstly, we magnify the small stego noise by multiplying the speckle noise to a given image and then we estimate the denoised image by using the soft thresholding method. Because the noises are not perfectly eliminated, some noises exist in the estimated cover image. If the given image is the cover image, then the remained noise will be very small, but if it is the stego image, the remained noise will be relatively large. The parent-child relationship in the wavelet domain will be slighty broken in the stego image. From this characteristic, we extract the joint statistical moments from the difference image between the given image and the denoised image. Additionally, four statistical moments are extracted from the denoised image for the proposed steganalysis method. All extracted features are used as the input of MLP(multilayer perceptron) classifier. Experimental results show that the proposed scheme outperforms previous methods in terms of detection rates and accuracy.

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.121-124
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• 2001

The main characteristic of the Electron Beam Welding technique is its high energy density which produces thin and deep welds with very little distortion. High accelerated electrons, focused in a beam of 0.5 ∼ 2mm diameter, produce narrow welds with deep penetration. The result is a small HAZ as well as a low and uniform distortion which is predictible within very narrow limits. But the small diameter of the EB increases the requirements for the equipment control system for centering the beam on the welding joint in order to avoid any lack of fusion. Therefore, in this paper, we introduce the system developed at our company and the quality of welding zone, the detail function of system.

• The Journal of Fisheries Business Administration
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• v.42 no.3
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• pp.31-39
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• 2011

This paper attempts to extend such analysis to the rather more difficult problem of optimal management of transnational fish stocks jointly owned by two countries. Transboundary fish such as Mackerel creates an incentive to harvest fish before a competitor does and leads to over-exploitation. This tendency is especially poignant for transnational stocks since, in the absence of an enforceable, international agreement, there is little or no reason for either government or the fishing industry to promote resource conservation and economic efficiency. In the current paper I examine a game theoretic setting in which cooperative management can provide more benefits than noncooperative management. A dynamic model of Mackerel fishery is combined with Nash's theory of two countries cooperative games. A characteristic function game approach is applied to describe the sharing of the surplus benefits from cooperation and noncooperation. A bioeconomic model was used to compare the economic yield of the optimal strategies for two countries, under joint maximization of net benefits in joint ocean. The results suggest as follows. First, the threat points represent the net benefits for two countries in absence of cooperation. The net benefits to Korea and China in threat points are 2,000 billion won(${\pi}^0_{KO}$) and 1,130 billion won(${\pi}^0_{CH}$). Total benefits are 3,130 billion won. Second, if two countries cooperate one with another, they reach the solution payoffs such as Pareto efficient. The net benefits to Korea and China in Pareto efficient are 2,785 billion won(${\pi}^0_{KO}$) and 1,605 billion won(${\pi}^0_{CH}$) or total benefits of 4,390 billion won : a gain of 1,260 billion won. Third, the different price effects under the two scenarios show that total benefit rise as price increases.

• Geomechanics and Engineering
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• v.36 no.6
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• pp.601-618
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• 2024

The joint probability distribution of uncertain geomechanical parameters of geotechnical strata is a crucial aspect in constructing the reliability functional function for roof structures. However, due to the limited number of on-site exploration and test data samples, it is challenging to conduct a scientifically reliable analysis of roof geotechnical strata. This study proposes a Copula method based on small sample exploration and test data to construct the intensity characteristics of roof geotechnical strata. Firstly, the theory of multidimensional copula is systematically introduced, especially the construction of four-dimensional Gaussian copula. Secondly, data from measurements of 176 groups of geomechanical parameters of roof geotechnical strata in 31 coal mines in China are collected. The goodness of fit and simulation error of the four-dimensional Gaussian Copula constructed using the Pearson method, Kendall method, and Spearman methods are analyzed. Finally, the fitting effects of positive and negative correlation coefficients under different copula functions are discussed respectively. The results demonstrate that the established multidimensional Gaussian Copula joint distribution model can scientifically represent the uncertainty of geomechanical parameters in roof geotechnical strata. It provides an important theoretical basis for the study of reliability functional functions for roof structures. Different construction methods for multidimensional Gaussian Copula yield varying simulation effects. The Kendall method exhibits the best fit in constructing correlations of geotechnical parameters. For the bivariate Copula fitting ability of uncertain parameters in roof geotechnical strata, when the correlation is strong, Gaussian Copula demonstrates the best fit, and other Copula functions also show remarkable fitting ability in the region of fixed correlation parameters. The research results can offer valuable reference for the stability analysis of roof geotechnical engineering.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.1-6
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• 2007

This paper presents a new experimental Servo-Parameter tuning technique for a 6-axes articulated robot manipulator, especially considering robot's dynamics. First of all, investigation for proportional gain of velocity control loop by using a Dynamic Signal Analyzer(DSA) is performed. Using the FUNCTION characteristic of DSA based on the Bode plot, the Bode plot of open loop transfer function can be obtained. In turn, the integral gain of a servo controller can be found out by using the integration time constant extracted from the Bode plot of open loop transfer function. In the meanwhile, the positional gain of the servo controller can be obtained by using the Bode plot of the closed loop transfer function. Using the experimental gain tuning technique proposed in this paper, the testing linear motion of DR6-II robot has been shown to be more accurate rather than the motion with a conventional(empirical) gain tuning technique in Doosan Mecatec Co., Ltd., by improving the dynamic response of the robot as well as synchronizing each joint velocity according to the positional command of an end-effector.