• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.218-223
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• 1999

A piezoelectric flextentional deep-water sonar transducer has been simulated using a coupled FE-BEM. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with extern리 electrical excitation conditions as well as external acoustic pressure loading conditions. Different results are available such as steady-state frequency response for RX and TX, displacement modes, directivity patterns, back-scattering patterns, resonant frequencies, bandwidths, quality factors, transmitting voltage (TV) responses, input receiving sensitivity (RS) responses. White the present barrel-stave typed sonar transducer of the piezoelectric material is being simulated, the external surface of the transducer is modified in order to allow the same water pressure to be applied to the inner and the outer surfaces of the transducer. With this modification for deep-water application, the resonance frequency of the modified flextentional sonar transducer becomes much lower than that of the unmodified flextentional sonar transducer. The results of the present sonar transducer modelling are also compared with those of a commercial package such as ATILA.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.4
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• pp.5-12
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• 2001

This paper presents the simulation methodology of the interior noise of vehicle using the frequency response function based hybrid modeling of the system which consists of multi-subsystem models obtained by the test or analysis. The complex systems such as a trimmed body of high modal density and a powertrain were modeled by using experimental data, and a sub-frame of a vehicle of low modal density was modeled by finite element data. Modeling of the whole system was executed and validated in the two stages. The first stave is combining the trimmed body and the sub-frame, and the second stage is attaching the powertrain, which is a exciting source, to the combined model of the first stage. The input force to the system was modeled as an equivalent force in the virtual space, which was obtained from impedance method using the FRFs of the powertrain and the responses. The interior noise predicted by the proposed method was very close to the direct measurement, which showed feasibility of the proposed modeling procedure. Since the methodology is easily applied to both the transfer path analysis of structure-borne noise and the analysis of noise contribution of a sub-system, it is expected to be a strong tool for design change of a vehicle in the earlier stare.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.9
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• pp.922-927
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• 2009

The transducers used in active sonar on surface ships are packed in a specific geometry in the array drum in order to meet the requirements such as the source level, directional beam pattern, etc. This paper describes the acoustic characteristics of the cylindrical array which is based on a 64 vertical staves arrangement, each stave composed 5 independent transducers. Firstly, the single transducer on the rigid baffle in the water is analyzed with the Finite Element Method. From the result of the FE analysis nodal velocities on the radiation surface is calculated and used with the boundary conditions of the transducers mounted on the array drum. Then the acoustic pressure is calculated in the field points using the Boundary Element Method and the other acoustic informations, the source level, beam pattern, near field and far-field distance, were acquired.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.125-128
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• 2002

The automotive industry have made an effort to reduce the weight of vehicle structures with increased safety, while initial model of the final product does not contain any prehistoric effects in a design stave. It takes lots of time to calculate forming effects that have great influences on the energy absorption of structures. In this paper, finite element inverse analysis is adopted to calculate forming effects, such as thickness variation and effective plastic strain as well as an initial blank shape with small amount of computation time. Crash analysis can be directly performed after inverse analysis of the forming process without remeshing scheme. The direct mesh mapping method is used to calculate an initial guess from the sliding constraint surface that is extracted from the die and punch set. Analysis results show that energy absorption of structures is increased with consideration of forming effects and finite element inverse analysis is usefully applicable to calculate forming erects of vehicle structures for the crash analysis.

• Food Science and Preservation
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• v.8 no.4
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• pp.374-378
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• 2001

We investigated the change of microfloral states during drying processing and storage of dried persimmon. Initial stave of drying, a total bacteria counts of dried persimmon which was made the rural region of Sangju province were higher than that of downtown but after 7 weeks, there was no differents. A total cell count of bacteria decreased during drying processing but mold and yeast increased. In a storage test of dried persimmon at a different temprature, 3$0^{\circ}C$, room temp. 4$^{\circ}C$, respectively, low temprature storage was effectvie not only to retard the growth of microorganism but also maintain the suitable appearence.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.559-567
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• 1999

A piezoelectric flextentional sonar transducer has been simulated using a coupled FE-BEM. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Different results are available such as steady-state displacement modes, underwater directivity patterns, resonant frequencies, bandwidths, quality factors, output acoustic powers and transmitting voltage responses. It is shown that the present barrel-stave sonar transducer of the piezoelectric material produces flextentional displacements which could be related with higher output power, lower quality factor and more omnidirectional beam pattern than other types of sonar transducers. The results of the present sonar transducer modelling are also compared with those of a commercial package such as ATILA.

• The Korean Journal of Zoology
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• v.38 no.2
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• pp.196-203
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• 1995

The c-myc proto-oncogene, one of the immediately earlY genes, is expressed in various mammalian cell types and heavily involved in the regulation of cell proliferation and differentiation. To determine endogeneous expression pattern of c-myc gene in preimpBantation mouse embwos, we employed a reverse transcription coupled to polvrnerase chain reaction (RT-PCR). Transcript of c-myc was detected at fertilized embryos as a maternal transcript. At the early two-cell stave, transcript of c-myc gene was hardly detected, bu, appeared at late two-cell embryos as a zygotic transcript. The level of c-myc expresion was increased at later stases and peaked at blastocvst stage. To examine the functional role of promoter region for c-myc gene transcription, we fused the 5'upstream region (1.8 kb) including econ 1 of c-myc genomic DNA with E. coli lacE gene fnamed as pcMYC-laczl. pcMYC-lacZ was microiniected into the pronscleus of mouse one-cell embryovs, and p·salactosidase activity was determined tv histochemical staining with X-gal at different stases. f-galactosidase activity was detected only at blastocyst, but not at the earlier stage embryos. This result indicates that c-myc gene is transcriptionallv active during mouse preimplantation development.

• The Journal of Korean Association of Computer Education
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• v.7 no.4
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• pp.61-66
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• 2004

Electronic commerce that use Mobile Phone according as the radio Internet develops rapidly and performance of Mobile Phone develops is activated. It is said that electronic commerce that use these Mobile Phone is M-Commerce. Also, the most important controversial point is data security or an user certification technology at these electronic commerce, there are research reactor WPKI and WTLS about this technology. However, when transmit message again after sign electronic documents in Mobile Phone, if do not encrypt, danger exists to be exposed to outside. Therefore, in this paper, designed system to encipher document that handle and handles user certification applying XML electronic sign technique in Mobile environment. Prevent of XML electronic sign in Mobile environment through this paper, and can stave off danger from outside by enciphering electronic sign document.

• Journal of Sensor Science and Technology
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• v.8 no.5
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• pp.377-387
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• 1999

A piezoelectric flextentional deep-water sonar transducer has been designed using a coupled FE-HEM. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Different results are available such as steady-state frequency response for TX displacement modes, directivity patterns, resonance frequencies, TVRs. While the conventional barrel-stave typed sonar transducer of the piezoelectric material is designed, the external surface of the transducer is modified in order to allow the same hydrostatic pressure to be applied onto the inner and the outer surfaces of the transducer. With this modification for deep-water application, a new resonance mode is generated at lower frequency. This lower resonance mode can be adjusted according to the degree of the outer surface modification.

• Archives of Plastic Surgery
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• v.38 no.5
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• pp.683-686
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• 2011

Purpose: Craniosynostosis of three or more cranial sutures was not common. "Mercedes Benz pattern," named by Moore1 was a rare form of craniosynostosis and had an atypical pattern of premature closure of cranial suture. It was not reported in Republic of Korea. We report this case with literature review. Methods: A 13-months-old male patient visited our clinic due to exophthalmos. He showed normal developmental course. Other neurological tests were normal but he was Crouzon syndrome patient. CT scans showed bilateral lambdoid and posterior sagittal sutures were fused and the length of the skull was extended. Cranioplasty with pi craniotomy & Barrel-Stave osteotomy and recombination of the bone flap was performed. Results: The patient was discharged after post operative 10 days without any complications. In follow up visit after 2.7 years, he was in good state without recurrence and functional abnormality of skull. Conclusion: This was the first case of Mercedes Benz pattern craniosynostosis with Crouzon syndrome in Korea. This type of craniosynostosis has to be considered differently from single type of craniosynostosis or typical syndromic craniosynostosis clinically and surgically.