• Journal of Welding and Joining
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• v.4 no.2
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• pp.47-52
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• 1986

Friction Welds are formed by the mechanisms of diffusion as well as mechanical inter-locking. The severe plastic flow at the interface by the forge action of the process brings the subsurface so close together that detection of any unbounded area becomes very difficult. No reliable method is available so fat to determine the weld quality nondestructively. The paper presents an attempt to determine weld strength quantitatively using the ultrasonic pulseecho method. The new approach calculates the coefficient of reflection based on measured amplitudes of the echoes. This coefficient provides a single quantitative measurement which involves both acoustic energy reflected at the welded interface as well as transmitted across the interface. As a result, it was known that the quantitative relationship between the coefficient and the weld strength (torsional strength) could be drawn.

• Journal of Korean Library and Information Science Society
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• v.10
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• pp.1-26
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• 1983

In the study of the Sutras in our country. We can seak important not only the study of real-Sutras, but the study of counterfeit-Sutras. This study examines into the completion circumstance of Monglyun Kyung. Therefore, Following items were discussed. (1) Monglyun Kyung was conceived by the idea of Monglyun's biography. (2) Monglyun Kyung was derived and developed by Ulanboon Kyung (3) Monglyun Kyung was effected by Donhwang Byunmoon's Monglyun Byunmoon, and Completed about the eleventh century in Korea. But it was not the simple imitation of Byunmoon. Thereby it was completed, undergo various influence, by other the Sutras and the theses. As a result, Monglyun Kyung was disclosed as excellent Korea's forge the Sutras. For it had excellent aspect like the Sutras.

• Transactions of Materials Processing
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• v.16 no.6
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• pp.443-446
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• 2007

The semi-solid process has been developed near net-shape components for kinds of methods. Thixo-forming with reheating prepared billet and rheo-forming with cooled melt until semi-solid state. Material is applied electromagnetic stirring system to slurry with aluminum 6061 alloy. An experiment has variation factors which are pressure, solid-fraction, stirring current and stirring time. The mechanical properties are compared to forge sample with to apply heat treatment T6. This study is researched function a virtual pressure and fine shape zone. Optimum pressure is found to prevent defect of porosity.

• Convergence Security Journal
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• v.6 no.2
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• pp.21-29
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• 2006

Recently, illegal manipulation and forgery threats on computer softwares are increasing. Specially, forge the code of program and disrupt normal operation using a malicious loader program against the Internet application client. In this paper, we first analyze and generate signatures of malicious loader detection. And, we propose a method to secure the application client based on profiling which can detect and filter out abnormal malicious loader requests.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.973-976
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• 2005

In IEEE 802.15.4 (Low-Rate Wireless Personal Area Network) specification, a successful reception and validation of a data or MAC command frame can be confirmed with an acknowledgment. However, the specification does not support security for acknowledgment frame; the lack of a MAC covering acknowledgments allows an adversary to forge an acknowledgment for any frame. This paper proposes an identity authentication mechanism at the link layer for acknowledgment frame in IEEE 802.15.4 network. With the proposed mechanism there is only three bits for authentication, which can greatly reduce overhead. The encrypted bit stream for identity authentication will be transmitted to device by coordinator within association process. Statistical method indicates that our mechanism is successful in handling MAC layer attack.

• Speech Sciences
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• v.10 no.3
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• pp.29-36
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• 2003

The purposes of this study was to conduct a correlational analysis among $F_^{0}$, Jitter, Shimmer, and NHR (HNR), and NNE estimated by three speech analysis softwares, MDVP, Praat and Dr. Speech. Thirty females and 15 males with normal voice participated in the study. We used Sound Forge 6.0 to record their voice. MDVP, Praat and Dr. Speech were used to measure the acoustic parameters. The Pearson correlation coefficient was determined through a statistical analysis. The results came out as follows: Firstly, there was a strong correlation between $F_^{0}$ and Shimmer of both instruments. However, there was no correlation between Jitter of both instruments. Secondly, Shimmer showed a stronger correlation with HNR, NHR, and NNE than Jitter. Therefore, Shimmer was considered to be more useful and sensitive parameter to identify dysphonic voice compared to jitter.

• Speech Sciences
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• v.13 no.2
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• pp.19-33
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• 2006

The purpose of this paper was to examine acoustical characteristics of phonatory offset-onset mechanism in the connected speech of female adults with stuttering and normal nonfluency. The phonatory offset-onset mechanism refers to the laryngeal articulatory gestures. Those gestures are required to mark word boundaries in phonetic contexts of the connected speech. This mechanism included 7 patterns based on the speech spectrogram. This study showed the acoustic features in the connected speech in the production of female adults with stuttering (n=1) and normal nonfluency (n=3). Speech tokens in V_V, V_H, and V_S contexts were selected for the analysis. Speech samples were recorded by Sound Forge, and the spectrographic analysis was conducted using Praat. Results revealed a stuttering (with a type of block) female exhibited more laryngealization gestures in the V_V context. Laryngealization gesture was more characterized by a complete glottal stop or glottal fry both in V_H and in V_S contexts. The results were discussed from theoretical and clinical perspectives.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.5
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• pp.48-55
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• 2010

The Door hinge is a very important part for door sagging performance of a vehicle. It is divided into two classes as a forge- and press-type according to a manufacturing technique. The press-type door hinge is cheap, but shows low strength. To apply the press-type door hinge to a fullsized car with satisfactory door sagging performance, we optimized the design parameters of the door hinge using the DFSS method. As a result, the effective design parameters of the press-type door hinge with good door sagging performance were obtained.

• Journal of Welding and Joining
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• v.19 no.3
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• pp.267-273
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• 2001

In this study, welding phenomena involved in formation of penetrators during high frequency electric resistance welding were investigated. High speed cinematography of the process revealer that a molten bridge between neighboring skelp edges forms at apex point and travels along narrow gap toward to welding point at a speed ranging from 100 to 400 m/min. The bridge while moving along the narrow gap swept away oxide containing molten metal from the gap, providing oxide-free surface for a forge-welding at upsetting stand frequency of the budge formation, travel distance and speed of the bridge were affected by the heat input rate into strip. The travel distance and its standard deviation were found to have a strong relationship with the weld defect density. Based on the observation, a new mechanism of the penetrator formation during HF ERW process is proposed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.156-159
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• 2005

The outer race of CV(constant velocity) joint is an important load-supporting automotive put that transmits torque between the transmission gear box and driving wheel. The outer race is difficult to forge because its shape is very complicated and the required dimensional tolerances are very small. To guarantee the dimensional accuracy of the forged CV Joint, the quick and precise measurement is required to increase the inspection speed of forged products. Therefore in this study, PP(Pre-Position) Device to decrease the inspection time of measuring system has been developed to cope with forging cycle time. The measured inspection time confirms that the PPD is very effective in decreasing inspection time.