• Journal of information and communication convergence engineering
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• 제16권3호
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• pp.153-159
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• 2018

In this paper, we present a three-dimensional (3D) optical encryption technique for quick response (QR) code using computational synthesized integral imaging, computational volumetric reconstruction, and double random phase encryption. Two-dimensional (2D) QR code has many advantages, such as enormous storage capacity and high reading speed. However, it does not protect primary information. Therefore, we present 3D optical encryption of QR code using double random phase encryption (DRPE) and an integral imaging technique for security enhancement. We divide 2D QR code into four parts with different depths. Then, 2D elemental images for each part of 2D QR code are generated by computer synthesized integral imaging. Generated 2D elemental images are encrypted using DRPE, and our method increases the level of security. To validate our method, we report simulations of 3D optical encryption of QR code. In addition, we calculated the peak side-lobe ratio (PSR) for performance evaluation.

• East Asian mathematical journal
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• 제34권3호
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• pp.317-330
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• 2018

We develop a mathematical model for the obesity dynamics to investigate the long term obesity trend with the consideration of psychological and social factors due to the increasing prevalence of obesity around the world. Many mathematical models for obesity dynamics adopted the modeling idea of infectious disease and treated overweight and obese people infectious and spreading obesity to normal weight. However, this modeling idea is not proper in obesity modeling because obesity is not an infectious disease. In fact, weight gain and loss are related to social interactions among different weight groups not only in the direction from overweight/obese to normal weight but also the other way around. Thus, we consider these aspects in our model and implement personal weight gain feature, a psychological factor such as body image dissatisfaction, and social interactions such as positive support on weight loss and negative criticism on weight status from various weight groups. We show that the equilibrium point with no normal weight population will be unstable and that an equilibrium point with positive normal weight population should have all other components positive. We conduct computer simulations on Korean demography data with our model and demonstrate the long term obesity trend of Korean male as an example of the use of our model.

• 전자공학회논문지B
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• 제30B권4호
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• pp.104-115
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• 1993

The motion compensated coding (MCC) technique, which exploits the temporal redundancies in the moving images with the motion estimation technique,is one of the most popular techniques currently used. Recently, a variable block size(VBS) motion estimation scheme has been utilized to improve the performance of the motion compensted coding. This scheme allows large blocks to the used when smaller blocks provide little gain, saving rates for areas containing more complex motion. Hence, a new VBS motion estimation scheme with a hierarchical structure is proposed in this paper, in order to combine the motion vector coding technique efficiently. Topmost level motion vector, which is obtained by the gain/cost motion estimation technique with selective motion prediction method, is always transmitted. Thus, the hierarchical VBS motion estimation scheme can efficiently exploit the redundancies among neighboring motion vectors, providing an efficient motion vector encoding scheme. Also, a restricted search with respect to the topmost level motion vector enables more flexible and efficient motion estimation for the remaining lower level blocks. Computer simulations on the high resolution image sequence show that, the VBS motion estimation scheme provides a performance improvement of 0.6~0.7 dB, in terms of PSNR, compared to the fixed block size motion estimation scheme.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2007년도 학술대회 3부
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• pp.326-333
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• 2007

To simulate solid dynamics,a we must com-pute the mass, the center of mass, and the products of inertia about the axes of the body of interest. These mass property computations must be continuously re-peated for certain simulations with rigid bodies or as the shape of the body changes. We introduce a GPU-friendly algorithm to approximate the mass properties for an arbitrarily shaped body. Our algorithm converts the necessary volume integrals into surface integrals on a projected plane. It then maps the plane into a frame-buffer in order to perform the surface integrals rapidly on the GPU. To deal with non-convex shapes, we use a depth-peeling algorithm. Our approach is image-based; hence, it is not restricted by the mathematical or geometric representation of the body, which means that it can efficiently compute the mass properties of any object that can be rendered on the graphics hardware. We compare the speed and accuracy of our algorithm with an analytic algorithm, and demonstrate it in a hydrostatic buoyancy simulation for real-time applications, such as interactive games.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제6권6호
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• pp.628-634
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• 2000

본 논문에서는 LCD(Liquid Crystal Display) 컨트롤러와 LCD 구동 칩 사이의 신호 전송에서 전력 소비 및 전자기 장애(EMI)를 줄이기 위한 데이타 코딩 방법을 제안하였다. 제안한 방식은 컴퓨터의 일반적인 텍스트 화면에 대한 데이타 천이(transition)를 감소시키는 방식으로 하드웨어 구조가 간단하여 실시간 처리가 요구되는 LCD 구동 시스템에 적용하기 용이하다. 제안한 방식의 성능 분석을 위해 컴퓨터를 이용한 시뮬레이션을 수행하였으며 기존의 코딩 방식과의 성능 비교 및 평가를 하였다. 시뮬레이션을 통해 제안한 방식이 기존 방식에 비하여 텍스트 화면과 그림 화면에 대해서 switching activity를 현저히 줄일 수 있음을 확인하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.235-240
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• 2002

This paper shows the desist concept of an ATS(Antenna Tracking Software) to control the movement of the MSC(Multi-Spectral Camera) antenna. The MSC has a two-axes directional X-band antenna for image transmission to KGS(KOMSAT2 Ground Station). The main objective of the ATS is to drive the APM(Antenna Pointing Mechanism) to the required elevation and the azimuth position according to an appropriate TPF(Tracking Parameter File). The ATS is implemented as one task of the SBC(Single Board Computer) software, which uses VxWorks as a real time OS. The ATS has several operational modes such as STANDBY mode, First EL mode, First AZ mode, Normal Operation mode, and so on. The ATS uses two PI controllers fur the velocity and the position loop respectively, to satisfy the requirements specification. In order to show the feasibility of the described design concept, the various simulations and the experiments are performed under specific test configuration.

• International Journal of Vascular Biomedical Engineering
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• 제2권2호
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• pp.27-32
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• 2004

The objective of the present study is to visualize the steady and pulsatile flow fields in a branching model by using a high-resolution PIV system. A bifurcated flow system was built for the experiments in the steady and pulsatile flows. Harvard pulsatile pump was used to generate the pulsatile velocity waveforms. Conifer powder as the tracing particles was added to water to visualize the flow fields. CCD cameras($1K{\times}1K$(high resolution camera) and $640{\times}480$(low resolution camera)) captured two consecutive particle images at once for the image processing of several cross sections on the flow system. The range validation method and the area interpolation method were used to obtain the final velocity vectors with high accuracy. The results of the image processing clearly showed the recirculation zones and the formation of the paired secondary flows from the distal to the apex of the branch flow in the bifurcated model. The results also indicated that the particle velocities at the inner wall moved faster than the velocities at the outer wall due to the inertial force effects and the helical motions generated in the branch flows as the flow proceeded toward the outer wall. Even though the PIV images from the high resolution camera were closer to the simulation results than the images from the low resolution camera at some locations, both results of the PIV experiments from the two cameras generally agreed quite well with the results from the computer simulations. Therefore, instead of using the expensive stereoscopic PIV or 3D PIV system, the three-dimensional flow fields in a bifurcated model could be easily and exactly investigated by this study.

• 한국융합학회논문지
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• 제11권9호
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• pp.15-20
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• 2020

소프트웨어가 국가의 혁신 및 성장, 가치 창출에 핵심 요소가 되고 있고, 이에 소프트웨어 관련 교육은 필수적인 상황이다. 공학 교육에 대한 수행방법 가운데 하나로, 실행이 어려운 상황에 대하여 유사한 환경에서 교육할 수 있는 가상 시뮬레이션을 통한 교육이 다양하게 이루어지고 있다. 최근 생산 현장에 스마트팩토리의 구축이 확산되고 있고, 비전 시스템을 활용한 제품 검사가 수행되고 있다. 그러나 비전 시스템에 대한 운영 기술의 부족으로 많은 어려움을 겪고 있으나, 비전 시스템 교육을 위한 시스템 구축에 많은 비용이 필요하다. 본 논문에서는 컴퓨터와 물리엔진의 카메라 기능을 융합하여 영상을 추출하고 전송할 수 있는 교육용 가상 시뮬레이션 모델을 제안한다. 제안 모델의 실험 결과 평균 35.4FPS로 30Hz 이상의 이미지 생성이 가능하며, 22.7ms의 시간으로 이미지를 송수신할 수 있어, 교육용 가상 시뮬레이션 교육 환경에서 활용할 수 있을 것이다.

• 한국정보기술학회논문지
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• 제16권11호
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• pp.35-41
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• 2018

전기 임피던스 단층촬영법 (EIT, electrical impedance tomography)은 비파괴검사의 일종으로 관심영역 외부에 설치된 전극에서 측정된 전압으로부터 내부의 저항률분포를 얻는 기술이다. 그러나 EIT에서 영상복원은 타고난 비선형성 (non-linearity)과 부정치성 (ill-posedness) 때문에 만족할만한 복원결과를 얻기 어렵다. 일반적으로 신경회로망은 비선형 시스템의 입력 및 출력 관계를 효율적으로 모델링 할 수 있다. 이 논문은 다층 신경회로망을 이용하여 원형인 표적의 위치(중심좌표)와 크기(반지름)를 추정하는 방법을 제안한다. 제안한 방법의 성능을 알아보기 위해, 신경회로망을 학습시키고 다양한 컴퓨터 모의실험을 수행하였고 결과로부터 제안한 방법의 만족할만한 추정성능을 확인할 수 있었다.

• 한국전자파학회논문지
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• 제30권5호
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• pp.407-417
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• 2019

탄도 미사일은 상공에서 자유 낙하하며 표적을 요격하기 때문에 탄도 미사일에 부착되는 탐색기는 높은 지표각에서 해상 클러터 영향을 받게 되며, 그 결과 탐색기의 탐지 성능이 급격히 낮아지게 된다. 이를 해결하기 위해서는 다양한 시나리오 기반의 시뮬레이션들을 통한 해상 표적 탐지 성능 분석이 반드시 필요하다. 따라서 본 논문에서는 실제와 유사한 높은 지표각의 해상 클러터 수신 신호를 모델링한 후, 이를 신호 대 클러터 비에 따라 해상 표적 수신 신호와 합성하여 2차원 레이다 영상을 생성한다. 이후, 레이다 영상에 2차원 CA-CFAR 탐지기를 적용하여 다양한 시나리오에서 해상표적 탐지 성능을 분석하였다. CAD 모델과 전자기 수치해석 도구를 사용한 시뮬레이션 결과, 지표각과 방위각에 따라 해상 표적의 탐지 여부가 다르게 나타남을 확인할 수 있었다.