• 한국자동차공학회논문집
• /
• 제13권2호
• /
• pp.83-92
• /
• 2005

An electromagnetic acoustic transducer (EMAT) is a unique probe that does not require a couplant or gel and also can usually generate or detect an ultrasonic wave into specimens across a small gap. It, therefore can be applied in a noncontact mode with a high degree of reproducibility. Especially stiffness of composites depends on layup sequence of CFRP(carbon fiber reinforced plastics) laminates. It is very important to evaluate the layup errors in prepreg laminates. A nondestructive technique can therefore serve as a useful measurement for detecting layup errors. This shear wave for detecting the presence of the errors is very sensitive. A decomposition model has been used in the interpretation and prediction of test results. Test results have been com pared with model data. It is found that the high probability shows between tests and the model utilized in characterizing cured layups of the laminates. Also a C-scan method was used for detecting layup of the laminates because of extracting fiber orientation information from the ultrasonic reflection caused by structural imperfections in the laminates. Therefore, it was found that interface C-scan images show the fiber orientation information by using two-dimensional fast Fourier transform (2-D FFT).

• 정보처리학회논문지B
• /
• 제15B권4호
• /
• pp.307-314
• /
• 2008

본 논문에서는 이미지의 선에 대하여 워터마크 정보를 삽입 및 추출하는 기술을 제안한다. 기존의 워터마킹 기술이 이미지의 픽셀 밝기값을 이용하는 것과 달리 제안된 알고리즘은 이미지의 곡선들을 B-스프라인 곡선으로 모델화하여 B-스프라인 제어점을 추출하고 이를 주파수 영역으로 변환하여 워터마크를 삽입한다. 제어점에 Delaunay 삼각화를 적용하여 메시를 생성하고, 메시-스펙트럼 분석을 통하여 주파수 영역의 메시-스펙트럼 계수를 계산한다. 워터마크는 이 계수의 중간 주파수 성분에 스프레드 스펙트럼 방식으로 삽입한다. 워터마크가 삽입된 계수를 메시-스펙트럼 역변환을 통하여 제어점을 계산하고 이를 통하여 워터마크가 삽입된 B-스프라인 곡선을 재구성할 수 있다. 삽입된 워터마크는 원본 선 이미지를 사용하여 검출이 이루어진다. 먼저 대상 선 이미지를 B-스프라인 모델화하고 곡선의 굴곡점을 이용하여 원본 선 이미지와 동기화를 수행한다. 동기화된 이미지에서 워터마크 삽입과정과 같이 메시-스펙트럼 계수를 추출하고 원본 메시-스펙트럼 계수와의 차이값을 계산하여 워터마크를 추출한다. 마지막으로 랜덤 워터마크와 추정된 워터마크의 상관 계수를 계산하여 삽입된 워터마크를 확인할 수 있다. 실험을 통하여 제안된 워터마킹 알고리즘이 기존 알고리즘보다 기하학적 공격과 프린트-스캔 공격에 강인함을 보였다.

• 한국의류학회지
• /
• 제30권8호
• /
• pp.1242-1252
• /
• 2006

Many applications in computer graphics require complex, highly detailed models. However, to control processing time, it is often desirable to use approximations in place of excessively detailed models. Therefore, we have developed the notion of an optimal matrix to simplify the model surface which can then rapidly obtain high quality 2D patterns by flattening the 3D surface. Firstly, the woman's 3D body was modeled based on Size Korea data. Secondly, the 3D model was divided by shell and block for the pattern draft. Thirdly, each block was flattened by the grid and bridge method. Finally, we select the optimal matrix and demonstrate it's efficiency and quality. The proposed approach accommodates surfaces with darts, which are commonly utilized in the clothing industry to reduce the deformation of surface forming and flattening. The resulting optimal matrix could be an initiation of standardization for pattern flattening. This can facilitate much better approximations, in both efficiency and exactness.

• Smart Structures and Systems
• /
• 제23권2호
• /
• pp.195-205
• /
• 2019

An accurate non-model-based method for delamination identification of laminated composite plates is proposed in this work. A weighted mode shape damage index is formulated using squared weighted difference between a measured mode shape of a composite plate with delamination and one from a polynomial that fits the measured mode shape of the composite plate with a proper order. Weighted mode shape damage indices associated with at least two measured mode shapes of the same mode are synthesized to formulate a synthetic mode shape damage index to exclude some false positive identification results due to measurement noise and error. An auxiliary mode shape damage index is proposed to further assist delamination identification, by which some false negative identification results can be excluded and edges of a delamination area can be accurately and completely identified. Both numerical and experimental examples are presented to investigate effectiveness of the proposed method, and it is shown that edges of a delamination area in composite plates can be accurately and completely identified when measured mode shapes are contaminated by measurement noise and error. In the experimental example, identification results of a composite plate with delamination from the proposed method are validated by its C-scan image.

• 반도체디스플레이기술학회지
• /
• 제22권4호
• /
• pp.154-160
• /
• 2023

Recently, with the activation of eBook services, books are being published simultaneously as physical books and digitized eBooks. Paper books are more expensive than e-books due to printing and distribution costs, so demand for relatively inexpensive e-books is increasing. There are cases where previously published physical books cannot be digitized due to the circumstances of the publisher or author, so there is a movement among individual users to digitize books that have been published for a long time. However, existing research has only studied the advancement of the pre-processing process that can improve text recognition before applying OCR technology, and there are limitations to digitization depending on the condition of the book. Therefore, support for book digitization services depending on the condition of the physical book is needed. need. In this paper, we propose a method to support digitalization services according to the status of physical books held by book owners. Create images by scanning books and extract text information from the images through OCR. We propose a method to recover text that cannot be extracted depending on the state of the book using BERT, a natural language processing deep learning model. As a result, it was confirmed that the recovery method using BERT is superior when compared to RNN, which is widely used in recommendation technology.

• 한국콘텐츠학회논문지
• /
• 제12권9호
• /
• pp.136-145
• /
• 2012

다양한 체형을 지니고 있는 소비자들에게 만족스러운 착용감을 주는 기성복 생산을 위해서는 체형 특성이 반영된 원형 제작이 필요하다. 인체는 체형에 따라 곡면의 형태가 달라지므로, 인체의 곡면 형태를 세분화하여 그 특성을 원형 설계에 반영할 필요가 있다. 그러나 기성복에서는 개인의 체형별 특징을 일일이 반영하기 힘드므로, 기성복 원형 제작에 활용 가능한 체형별 인대 모형이 요구되고 있다. 따라서 본 연구에서는 삼차원 인체스캔 데이터를 활용하여 체형을 분석하고 각 체형에 따른 인대모형 개발 방법을 제시하였다. 30대 성인 여성의 상반신 삼차원 인체 형상 자료를 분석한 결과, 체형 특성은 보통체형, 비만체형, 마른체형으로 분류되었다. 상반신을 기준선을 두어 나누어 계측한 결과, 체형에 따라 유의적인 차이가 나타났다. 계측된 각 부위별 삼차원 인체 치수를 기본 원형 설계 시 허리다트 위치 및 분량 설정에 반영하여 체형별 상반신 기본 원형을 제작하였으며, 이를 바탕으로 입체모형을 제작하여 스캔, 모델링 작업을 거쳐 체형에 맞는 원형 인대 모형을 제시하였다. 인대 모형은 인체의 입체 형상을 만들기 위한 다트선을 포함하고 있어 기본 원형 제작 및 원형 활용에 도움이 될 것으로 사료된다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.710-713
• /
• 2005

Many impact or drop test researches of home appliances are published, but those of toys cannot be found easily. External impacts are the primary causes of fracture of toys. For impact proof design, the finished product should pass an impact test after molding design. There are several international toy safety standards or requirements such as US CPSC(Consumer Product Safety Commission), ASTM F963-96a, EN71 and so on. The puppy robot which patrols around the house, namely, the watchdog was selected to investigate toy safety because it has considerable weight and outer panels are made of plastics. First the model of watchdog robot was obtained by 3 dimensional scan. Surface data can be generated from 3D polygon data of the watchdog. A reliable drop simulation method for the watchdog was established using Pam-crash program according to Korean toy safety standards. When there is a low impact allowance value, the molding design should be reinforced or changed. It was found that the maximum impact stress reaches the ultimate stress of panel material.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2004년도 추계학술발표대회 논문집
• /
• pp.254-257
• /
• 2004

An electromagnetic acoustic transducers (EMAT) can usually generate or detect an ultrasonic wave into specimens across a small gap. Especially stiffness of composites depends on layup sequence of CFRP(carbon fiber reinforced plastics) laminates because the layup of composite laminates influences there properties. It is very important to evaluate the layup errors in prepreg laminates. A nondestructive technique can therefore serve as a useful measurement for detecting layup errors. It was shown experimentally that this shear waves for detecting the presence of the errors is very sensitive. It is found that high probability shows between tests and the model developed in characterizing cured layups of the laminates. Also a C-scan method was used for detecting layup of the laminates because of extracting fiber orientation information from the ultrasonic reflection caused by structural imperfections in the laminates. Therefore, it was found that interface C-scan images show the fiber orientation information by using two-dimensional fast Fourier transform(2-D FFT).

• Nuclear Engineering and Technology
• /
• 제55권1호
• /
• pp.248-253
• /
• 2023

Directly, it is not possible to measure the absorbed dose of radiopharmaceuticals in the organs of the human body. Therefore, simulation methods are utilized to estimate the dose in distinct organs. In this study, individual organs were separately considered as the source organ or target organ to calculate the mean absorption dose, which SAF and S factors were then calculated according to the target uptake via MIRD method. Here, ^99mTc activity distribution within the target was analyzed using the definition and simulation of ideal organs by summing the fraction of cumulative activities of the heart as source organ. Thus, GATE code was utilized to simulate the Zubal humanoid phantom. To validate the outcomes in comparison to the similar results reported, the accumulation of activity in the main organs of the body was calculated at the moment of injection and cardiac rest condition after 60 min of injection. The results showed the highest dose absorbed into pancreas was about 21%, then gallbladder 18%, kidney 16%, spleen 15%, heart 8%, liver 8%, thyroid 7%, lungs 5% and brain 2%, respectively, after 1 h of injection. This distinct simulation model may also be used for different periods after injection and modifying the prescribed dose.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집C
• /
• pp.482-484
• /
• 2001

In orthopedics, hip arthroplasty is the operation that replaces damaged hip joint to artificial joint. In hip arthroplasty, quite better result can be achieved if robot is applied to machine cavity in bone, especially when cementless stem is used. So several kinds of robots were introduced for hip arthroplasty, but they used MRI, CT Scan, vision analysis and real time tracking of bone position for registration of robot. To overcome shortage of conventional robot surgery, gauge based registration method was proposed and small robot was designed. In this method, small robot is mounted on femur, and its position is determined by gauge registration method. Operation procedure was performed on model femur and result was analyzed. This robotic hip surgery system is expected to more adaptable in operation room.