• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.7
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• pp.389-398
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• 2000

The popular methods to check the identity of individuals include passwords and ID cards. These conventional method for user identification and authentication are not altogether reliable because they can be stolen and forgotten. As an alternative of the existing methods, biometric technology has been paid much attention for the last few decades. In this paper, we propose an efficient system for recognizing the identity of a living person by analyzing iris patterns which have a high level of stability and distinctiveness than other biometric measurements. The proposed system is based on wavelet transform and a competitive neural network with the improved mechanisms. After preprocessing the iris data acquired through a CCD camera, feature vectors are extracted by using Haar wavelet transform. LVQ(Learning Vector Quantization) is exploited to classify these feature vectors. We improve the overall performance of the proposed system by optimizing the size of feature vectors and by introducing an efficient initialization of the weight vectors and a new method for determining the winner in order to increase the recognition accuracy of LVQ. From the experiments, we confirmed that the proposed system has a great potential of being applied to real applications in an efficient and effective way.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.42-48
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• 2014

The auxiliary-feed-water pump (AFWP) used to supply water during a station black out situation at nuclear power plants should meet the seismic qualification regulations stipulated in IEEE Std 323 and 344, so as to withstand earthquakes or dangerous situations. Here, we establish a model for the estimation of the structural integrity of this type of pump. If the natural frequency that results from a modal analysis is less than 33 Hz, we adopt a dynamic analysis, instead of a static analysis. A dynamic analysis was carried out taking into consideration seismic conditions such as the floor response spectra (FRS), an operation-base earthquake (OBE), and a safe-shutdown earthquake (SSE). Finally, an analytical estimation of the structural integrity of an AFWP is made through a comparison of calculated values and allowable values. If the result is less than the allowable stress, the pump is deemed to have good structural integrity. In addition, future studies will involve a stability check for rotor accidents that may occur during the operation of the pump.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.185-190
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• 1995

In recent years, many researcher have been interested in the stability of a thin beam. Among them, Pai and Nayfeh[1] had investigated the nonplanar motion of the cantilever beam under lateral base excitation and chaotic motion, but this study is associated with internal resonance, i.e. one to one resonance. Also Cusumano[2] had made an experiment on a thin beam, called Elastica, under bending loads. In this experiment, he had shown that there exists out-of-plane motion, involving the bending and the torsional mode. Pak et al.[3] verified the validity of Cusumano's experimental works theoretically and defined the existence of Non-Local Mode(NLM), which is came out due to the instability of torsional mode and the corresponding aspect of motions by using the Normal Modes. Lee[4] studied on a thin beam under bending loads and investigated the routes to chaos by using forcing amplitude as a control parameter. In this paper, we are interested in the motion of a thin beam under torsional loads. Here the form of force based on the natural forcing function is used. Consequently, it is found that small torsional loads result in instability and in case that the forcing amplitude is increasing gradually, the motion appears in the form of dynamic double potential well, finally leads to complex motion. This phenomenon is investigated through the poincare map and time response. We also check that Harmonic Balance Method(H.B.M.) is a suitable tool to calculate the bifurcated modes.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.24 no.1
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• pp.39-46
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• 2018

Background: In most human lives, 80 percent have problems with the ankle and can be solved with a treatment that is objective in proper assessment. Discrepacts in the ankle are also associated with walking patterns and affect hip and knee joints. An evaluation of hip flexion and extensor muscles was performed to check the strength of hip joints after ankle sprain patients application of arthesis. Methods: In the hospital in Bucheon, 20 outpatients who visited the hospital for treatment with ankle sprain were tested with 10 male and 10 female patients. The criteria for selection of the study subjects were randomly divided into those with joint movement techniques applied to the ankle joints and those with conservative physical therapy. Results: In applying arthrography and preservation physical therapy to patients with ankle sprain, a difference in muscle strength between hip flexion and extensor was noted in post-evaluation comparisons. There were significant differences in the assessment of walking speed and walking time between the two counties in the gait analysis assessment (p<.05). Conclusion: Studies have shown that applying arthrography to people with ankle sprain has a greater therapeutic effect than using conservative physical therapy.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.6
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• pp.36-50
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• 2009

To suggest the native plants combination for restoration of the dissected sloping area, the plant communities of thirty seven quadrats from five localities of mid-southern part of Korean peninsula were surveyed from 2007 to 2008. Their flora, vegetation structure, and dominant species based on the importance value were investigated. And the soil characters (pH, moisture content, water holding capacity, and organic matter) of each dominant species were analyzed. Also, germination tests were performed to check the stability of restored native plants using seed chips. As a result, 79 native plants were suggested for the dissected sloping area : 20 trees and subtrees for the upper layer, 18 shrubs and vines for the middle layer, and 41 herbs for the lower layer, taken together their flora, dominant species, vegetation structure, soil condition, germination test, flowering period.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.443-444
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• 2011

This paper discusses a model order reduction for large order rotor dynamics systems results from the finite element discretization. Typical rotor systems consist of a rotor, built-on parts, and a support system, and require prudent consideration in their dynamic analysis models because they include unsymmetric stiffness, localized nonproportional damping and frequency dependent gyroscopic effects. When the finite element model has a very large number of degrees of freedom because of complex geometry, repeated dynamic analyses to investigate the critical speeds, stability, and unbalanced response are computationally very expensive to finish within a practical design cycle. In this paper, the Krylov-based model order reduction via moment matching significantly speeds up the dynamic analyses necessary to check eigenvalues and critical speeds of a Nelson-Vaugh rotor system. With this approach the dynamic simulation is efficiently repeated via a reduced system by changing a running rotational speed because it can be preserved as a parameter in the process of model reduction. The Campbell diagram by the reduced system shows very good agreement with that of the original system. A 3-D finite element model of the Nelson-Vaugh rotor system is taken as a numerical example to demonstrate the advantages of this model reduction for rotor dynamic simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.466-483
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• 2017

Zen Cart is an open-source online store management system. It is used all over the world because of its stability and safety. Today, Zen Cart's session security mechanism is mainly used to verify user agents and check IP addresses. However, the security in verifying the user agent is lower and checking the IP address can affect the user's experience. This paper, which is based on the idea of session protection as proposed by Ben Adida, takes advantage of the HTML5's sessionStorage property to store the shared keys that are used in HMAC-SHA256 encryption. Moreover, the request path, current timestamp, and parameter are encrypted by using HMAC-SHA256 in the client. The client then submits the result to the web server as per request. Finally, the web server recalculates the HMAC-SHA256 value to validate the request by comparing it with the submitted value. In this way, the Zen Cart's open-source system is reinforced. Owing to the security and integrity of the HMAC-SHA256 algorithm, it can effectively protect the session security. Analysis and experimental results show that this mechanism can effectively protect the session security of Zen Cart without affecting the original performance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.245-251
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• 2001

A fretting wear tester is developed for experimental study on the fuel fretting problem of light water reactor. The feature of the developed tester is it can simulate the existence of gap between spring and fuel rod as well as different contacting force including the just-contact condition (0 N on the contact). Used are a servo-motor, an eccentric cylinder and lever mechanism for driving system. A spacer grid cell is constituted with four strap segments (each segment has a spring). This fretting wear tester can also be used as a fatigue tester of a spacer grid spring with the frequency of more than 10 Hz. It is required to simulate the frequency of the vibrating fuel rod due to flow-induced vibration in a reactor. In fretting wear test, up to two span-length of a fuel cladding tube can be accommodated. A specimen of cladding tube of one span-length is specially designed, which can be extended for two-span test. For .fatigue test, a device for clamping the spring fixture is installed additionally, Presently, the tester is designed for the condition of air environment and room temperature. The variation of the reciprocal distance is measured to check the stability of input force, which will be exerted to the cladding (for fretting wear. test) and the spring (for fatigue test) specimen.

• Clinics in Shoulder and Elbow
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• v.2 no.2
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• pp.133-137
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• 1999

Purpose: There are so many different methods with the their own advantages and disadvantages for acute AC dislocation and distal unstable clavicle fracture. We evaluated the usefulness of temporary Bosworth's coracoclavicular fixations using the cannulated screw and reviewed our clinical results. Materials and Methods: We evaluated 34 cases of temporary coracoclavicular fixations with cannulated screw and washer for acute AC dislocation(25cases in the Type V, Ⅲ) and distal unstable clavicle fracture(9cases in the Type ⅡB, Ⅱ+Ⅲ). All cases were fixed by the same techniques, guided cannulated screw under C-arm after the repair of the CC ligament within 1 week. Bases on the regular check, screws were removed at the 6-12 weeks under local anesthesia. The final clinical and radiological results(average 14 months follow-up) were rated with the UCLA scale. Results : All shoulders were gained nearly full ROM passively at the 3-4 weeks. The overall satisfactory resuIts(excellent or good) were achieved 88%(22/25) in the acute AC dislocation and all in the distal unstable clavicle fracture. There were no definite complications except three initial fixations loosening. Conclusion: Temporary Bosworth's coracoclavicular fixation using the cannulated screw with guided pin was simple precedure and provided enough initial stability for acute AC dislocation and distal unstable clavicle fracture.

• Structural Engineering and Mechanics
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• v.50 no.1
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• pp.19-36
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• 2014

This paper focuses on a model order reduction (MOR) for large-scale rotordynamic systems by using finite element discretization. Typical rotor-bearing systems consist of a rotor, built-on parts, and a support system. These systems require careful consideration in their dynamic analysis modeling because they include unsymmetrical stiffness, localized nonproportional damping, and frequency-dependent gyroscopic effects. Because of this complex geometry, the finite element model under consideration may have a very large number of degrees of freedom. Thus, the repeated dynamic analyses used to investigate the critical speeds, stability, and unbalanced response are computationally very expensive to complete within a practical design cycle. In this study, we demonstrate that a Krylov subspace-based MOR via moment matching significantly speeds up the rotordynamic analyses needed to check the whirling frequencies and critical speeds of large rotor systems. This approach is very efficient, because it is possible to repeat the dynamic simulation with the help of a reduced system by changing the operating rotational speed, which can be preserved as a parameter in the process of model reduction. Two examples of rotordynamic systems show that the suggested MOR provides a significant reduction in computational cost for a Campbell diagram analysis, while maintaining accuracy comparable to that of the original systems.