• 한국전기전자재료학회논문지
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• 제16권6호
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• pp.515-521
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• 2003

There are now many theoretical investigations and real manufactures for numerous applications of photonic crystals (PCs) associated with photonic band gap and photonic integrated circuits. However, there are some difficulties to design and fabricate the desired pattern quality. It is not easy to satisfy accurate critical dimension (CD) for patterns with arbitrary shapes and pitch sizes aligned in various directions. In this work, we report the optimum conditions to better fabricate and design, and greatly improve pattern quality in delineating two-dimensional (2D) PCs in the nanometer range using single- step e-beam lithography system with conventional exposure mode.

• Imaging Science in Dentistry
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• 제46권4호
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• pp.245-249
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• 2016

Purpose: This study was designed to evaluate differences in the required visibility of anatomic structures according to the diagnostic tasks of implant planning and periapical diagnosis. Materials and Methods: Images of a real skull phantom were acquired under 24 combinations of different exposure conditions in a cone-beam computed tomography scanner (60, 70, 80, 90, 100, and 110 kV and 4, 6, 8, and 10 mA). Five radiologists evaluated the visibility of anatomic structures and the image quality for diagnostic tasks using a 6-point scale. results: The visibility of the periodontal ligament space showed the closest association with the ability to use an image for periapical diagnosis in both jaws. The visibility of the sinus floor and canal wall showed the closest association with the ability to use an image for implant planning. Variations in tube voltage were associated with significant differences in image quality for all diagnostic tasks. However, tube current did not show significant associations with the ability to use an image for implant planning. conclusion: The required visibility of anatomic structures varied depending on the diagnostic task. Tube voltage was a more important exposure parameter for image quality than tube current. Different settings should be used for optimization and image quality evaluation depending on the diagnostic task.

• 대한기계학회논문집A
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• 제21권2호
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• pp.288-296
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• 1997

Curved beam elements with two nodes based on shallow beam geometry and strain interpolations are employed in eigenvalue analysis. In these elements, the displacement interpolation functions and mass matrices are consistent with strain fields. To assess the quality of the element mass matrix in free vibration problems, several numerical experiments are performed. In these analysis, both the inconsistent mass matrices using linear displacement interpolation function and the consistent mass matrices are used to show the difference. The numerical results demonstrate that the accuracy is closely related to the property of the mass matrix as well as that of the stiffness matrix and that the mass matrix consistent with strain fields is very beneficial to eigenvalue analysis. Also, it is proved that the strain based elements are very efficient in a wide range of element aspect ratios and curvature properties.

• 한국광학회지
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• 제16권5호
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• pp.456-461
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• 2005

제2조화파 발생용으로 사용되는 볼록평면거울로 구성된 비대칭 불안정 공진기형 Nd:YAG 레이저의 빔질 특성을 수치적으로 분석하였다. 분석은 $M^2$, 공진기 내에서의 빔허리 직경, 모드 부피의 계산을 통해서 이루어 졌다. 수치적 계산 결과는 레이저 헤드가 볼록레이저 거울 근방에 위치한 비대칭 공진기 구조가 될 때 고효율의 제2조화파를 발생할 수 있는 조건이잘 충족됨을 보였다.

• 동아시아식생활학회지
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• 제18권6호
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• pp.1056-1062
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• 2008

To evaluate the effect of irradiation on restructured pork jerky containing paprika and Japanese apricot extracts, the quality of protein was determined in vitro based on the formation of trypsin indigestible substrate inhibitor (TIS) and the computed protein efficiency ratio (C-PER) as determined based on the protein digestibility and amino acid analysis. In addition, we compared the effects of electron beam irradiation to those of gamma irradiation. Approximately 3% of the moisture content of pork jerky was reduced in response to irradiation with 3kGy administered using an electron beam however, no additional reduction was observed in samples that were subjected to higher doses of irradiation. In addition, there were no notable differences in the crude protein and fat content of pork jerky samples that were subjected to irradiation, regardless of dose. Furthermore, the total amino acids profiles did not change in response to electron beam irradiation. However, the in vitro protein digestibility increased by 7% in response to 3kGy of electron beam irradiation and 5kGy of gamma irradiation, but no significant changes in digestibility were not observed in response to treatment with higher doses. TIS quantified as trypsin inhibitors were formed in response to irradiation using the electron beam (3kGy) and gamma rays (5kGy), although there was a slight reduction in the production of TIS inhibitors in samples irradiated with higher doses. Moreover, only samples irradiated with 10kGy (electron beam and gamma ray) showed higher TBA values than those of the control samples. Finally, the C-PERs $(2.50{\sim}2.60)$ were greater in all of the irradiated pork jerky samples than in the control samples (2.22). Taken together, these results suggest that electron beam irradiation and the incorporation of extracts (paprika and Japanese apricot) may be useful methods of improving the nutritional quality of pork jerky.

• Journal of Welding and Joining
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• 제21권5호
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• pp.568-574
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• 2003

In the welding for the steel structure of H-beam with mild steel and 490N/$\textrm{mm}^2$ high tensile steel, we applied the fillet weld mostly and 6-8mm weld length(AISC-spec.). And a new developed metal-cored-wire is used in automatic welding as well as semi-automatic welding. In this study we have attempted to raise the welding productivity and to stabilize the quality on horizontal positions of fillet welding with the following items: - We improved the weld productivity using metal based cored wire with a high deposition rate in the steel structure of H-beam. - We tested the weldability and evaluated the quality of the weldmetal by horizontal fillet $CO_2$ welding. The process is carried out in combination with a special purpose metal-based FCW with excellent resistance to porosity and high welding speed. - We studied the micro structure of the weldmetal by the various welding conditions. - We studied the effect of welding residual stress by the welding conditions in T-joint. Therefore, it can be assured that more productive and superior quality of the weldmetal can be taken from this study results.

• International Journal of Automotive Technology
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• 제7권2호
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• pp.209-216
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• 2006

A study has been conducted for an optimal processing and an apparatus for manufacturing a laser welded tube for one-body formed bumper beam. The tube dimensions used in calculation were the thickness of 1.4 mm, the diameter of 105.4 mm and the length of 2000 mm. The tube was formed of a cold rolled high strength steel plate(tensile strength of 600 MPa). The two-roll bending method was the optimal tube forming process in comparison with the UO-bending method, the bending method on the press brake, the multi-step continuous roll-forming method and the 3-roll bending method. Monitoring of the welding quality was conducted and the seam tracking along the butt-joint lengthwise to the tube axis was also examined. The longitudinal butt-joint was welded by using a $CO_2$ laser welding machine equipped with a seam tracker and a plasma sensor. The $CO_2$ laser tube welding machine could be used for precise seam tracking and real-time monitoring of the welding quality. As a result, the developed laser welded tube could be used for a one-body formed automobile bumper beam.

• 한국정밀공학회지
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• 제21권7호
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• pp.136-144
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• 2004

Optimal process and system to produce the laser welded tube for one body formed bumper beam are studied. The calculated size of tube is a thickness of 1.4mm, diameter of 105.4mm and length of 2000mm. The tube is shaped from a cold rolled high strength steel sheet(tensile strength: 60kgf/$\textrm{mm}^2$ grade). Two roll bending method is the optimal tube shaping process compared to UO-bending, bending on press brake, multi-step continuous roll forming and 3 roll bending methods. Weld quality monitoring and seam tracking along the butt-joint lengthwise to the tube axis are also studied. The longitudinal butt-joint is welded by the $CO_2$ laser welding system equipped with a seam tracker and plasma sensor. The constructed $CO_2$laser tube welding system can be used for the precision seam tracking and the real-time monitoring of weld quality. Finally, the obtained laser welded tube can be used for one-body formed automobile bumper beam.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2023년도 춘계학술대회
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• pp.280-281
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• 2023

해양 환경에서의 무선 통신은 거리가 먼 통신에 많은 전력이 필요하며, 이로 인해 에너지 소비가 매우 크다. 또한, 해양 환경에서는 많은 제약 조건이 존재하기 때문에 기존의 무선 통신 기술을 적용하기 어렵기 때문에 이러한 문제를 해결하기 위한 새로운 기술이 필요하다. 본 논문에서는 해양 환경에서의 빔 선택 기술에 대해 연구하고 이를 통해 특정 지역에서 통신을 위해 필요한 빔을 선택하여 전송함으로써 전체 전력 소비를 줄이고, 신호 간 간섭을 최소화하여 더 나은 품질의 통신을 가능하게 한다. 이를 시뮬레이션을 통해 기존의 무선 통신 기술과 비교하여 에너지 효율성을 검증하고, 이러한 빔 선택 기술은 기존의 무선 통신 기술에 비해 전력 소비가 적으며, 더 나은 통신 품질을 제공함을 확인할 수 있었다. 따라서, 빔 선택 기술은 해양 환경에서의 효율적인 통신 시스템을 구축하는데 중요한 역할을 하며 이를 통해 보다 넓은 영역에서의 통신 품질 향상을 기대할 수 있다.

• 한국음향학회지
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• 제28권2호
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• pp.141-147
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• 2009

본 논문에서는 인체에 유해한 방사능 피폭량이 부챗살 형태의 Fan Beam 보다 상대적으로 적은 원추형 Cone Beam CT 시스템을 사용하여 3차원 영상을 빠르게 구성하기 위한 회전 기반법 알고리즘을 제안하였다. 그리고 계산 속도를 빠르게 하기 위하여 초월함수가 더 적은 3단계 회전 행렬을 이용하여 3차원 영상을 구현하였다. 또한 본 연구에서 구성한 영상을 일반적으로 사용되는 라돈 변환 알고리즘으로 구현된 3차원 영상과 비교하여 영상의 질은 평균적으로 단면 영상 당 10% 정도의 오차를 보이며 미약하게 저하되었으나 영상 구성 속도 면에서는 35배 개선됨을 보였다. 이는 대략 초당 $4{\sim}5$ 프레임을 얻을 수 있는 수치이며 간단한 구조를 가진 피사체라면 보다 많은 프레임을 얻을 수 있어 3차원 동영상을 실시간으로 구현할 수 있는 가능성을 보였다.