• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 1호
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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.

• 한국소음진동공학회논문집
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• 제11권4호
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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.

• 한국소음진동공학회논문집
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• 제19권9호
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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.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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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.

• 한국식품저장유통학회지
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• 제8권4호
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• pp.374-378
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• 2001

곶감의 건조 및 저장에 따른 미생물상의 변화를 조사하였다. 곳감의 제조 지역에 따라 건조 초기의 미생물수는 상주시 외곽지역의 곶감이 다소 높았으나 반건시상태가 되는 건조 7 주 후에는 두 지역의 미생물 수의 차이는 없었다. 건조가 진행됨에 일반세균과 초산균은 꾸준히 감소하여 7주 후에는 거의 관찰되지 않았으나 곰팡이와 효모 수는 점차 늘어나는 양상을 보였다. 곶감을 3$0^{\circ}C$$\pm$2, 실온(10~15$^{\circ}C$), 저온(4$^{\circ}C$$\pm$2)에서 7주간 저장한 결과 저온 저장구에서 미생물의 증가가 가장 낮았으며, 저온 저장과 상온 저장의 경우에는 저장 기간이 길어질수록 모든 미생물의 수가 증가하는 경향이었으나, 3$0^{\circ}C$ 저장구의 경우 저장 초기에 비하여 저장 기간이 길어질수록 효모와 초산균은 오히려 감소하였다. 외관의 경우에도 저장온도가 낮을수록 백분의 양은 많아지고 조직이 연화되는 기간도 길어지는 것으로 나타났다.

• 한국정보통신학회논문지
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• 제3권3호
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• pp.559-567
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• 1999

결합형 유한요소-경계요소 기법을 사용하여 압전체 유연형 쏘나 변환기를 시뮬레이션하였다. 쏘나 변환기의 역학적 구동을 3차원적으로 모델링하였고 전기적 외부 부하 조건을 가지고 분석하였다. 정상 상태 변위 모드, 방향 패턴, 공진 주파수, 대역,0-factor, 출력 압력, TV 응답과 같은 결과들을 보여준다. 본 논문의 술통 형태의 압전 재질 쏘나 변환기는 유연한 변위를 발생시키며, 다른 형태의 쏘나 변환기와 달리 고출력, 낮은 Q-factor, 향상된 전방위성을 가지도록 해준다. 본 연구에서 개발된 쏘나 변환기 모델링의 결과를 ATILA와 같은 상업적 소프트웨어와 비교하였다.

• 한국동물학회지
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• 제38권2호
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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.

• 컴퓨터교육학회논문지
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• 제7권4호
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• pp.61-66
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• 2004

무선 인터넷이 급속히 발전하고 모바일 폰의 성능이 발달함에 따라서 모바일 폰을 이용한 전자상거래가 활성화되고 있다. 이러한 모바일 폰을 이용한 전자상거래를 M-Commerce라고 한다. 또한 이러한 전자상거래시 가장 중요한 문제점으로는 데이터 보안이나 사용자 인증 기술이며, 이러한 기술에 관한 연구로 WPKI와 WTLS가 있다. 하지만 전자 문서를 모바일 폰에서 서명한 후 다시 메시지를 전송할 때 암호화 되지 않으면, 외부에 노출될 위험이 존재하고 있다. 따라서 본 논문에서는 모바일 환경에 XML 전자서명 기법을 적용하여 사용자 인증을 처리하고 처리한 문서를 암호화 하기 위한 시스템을 설계하였다. 본 논문을 통해 모바일 환경에서도 XML 전자서명을 제공할 수 있으며, 전자서명 문서를 암호화 함으로써 외부로부터의 위험을 예방할 수 있다.

• 센서학회지
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• 제8권5호
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• pp.377-387
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• 1999

결합형 유한요소-경계요소 기법을 사용하여 심해저용 유연형 압전체 쏘나 트랜스듀서를 설계하였다. 쏘나 트랜스듀서의 역학적 구동을 3차원적으로 모델링하였고 전기적 외부 부하 조건을 가지고 분석하였다. 쏘나 트랜스듀서의 정상 상태 변위 모드, 지향성, 공진 주파수, TVR과 같은 결과들을 보였다. 본 논문의 술통 형태의 압전체 쏘나 트랜스듀서를 설계하면서, 심해저용으로 사용하기 위해 쏘나 트랜스듀서의 내외부에 동일한 수압이 가해지도록 쏘나 트랜스듀서의 외부 표면 구조를 새롭게 변형시킨 결과 낮은 주파수의 새로운 공진 모드가 발생하였으나 그 크기는 외부 표면 구조 변형의 정도에 따라 조절될 수 있다.

• Archives of Plastic Surgery
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• 제38권5호
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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.