• Journal of Digital Contents Society
• /
• v.8 no.4
• /
• pp.459-465
• /
• 2007

In this paper, we implemented a ray-tracing simulator with a ray-launching technique and generated the propagation path of each ray in a multiple-wall indoor environment. In this simulator, we adopted two dimension ray-tracing techniques considering the reflection and penetration were dominant propagation factor in the indoor channel. From the result, we verified that this ray-tracing simulator shows the similar path pattern and delay distribution with the experiment results of the previous research. Especially, impulse responses of the ray were corresponding to reference result in non-line of sight of multiple-wall indoor environment. Furthermore, we confirmed that channel profiles having respectively different departure angle 1 degree to 7 degree were similar between them.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.6
• /
• pp.1511-1519
• /
• 2010

In this paper, we proposed and analyzed a RSSI based cooperative localization algorithm considering wireless propagation characteristics in indoor and outdoor environments for wireless sensor networks, which can estimate the BN position. The conventional RSSI based estimation scheme has low precision ranging due to instability propagation characteristics by time variable. Hence, we implemented ray-launching simulator for analysis of propagation characteristics in 4 case, and experimented proposed localization scheme with 4 RN and 1 to 5 BN. Simulation results show that NLCA has estimation error as 2m-3.5m, however, proposed CLA/ECLA has 1.3m-2.5m/0.5m-1.2m by same environments. Therefore, if we can consider channel characteristics, the proposed algorithm provides higher localization accuracy than RSSI based conventional one.

• Journal of the Korea Computer Graphics Society
• /
• v.2 no.1
• /
• pp.1-6
• /
• 1996

In ray tracing of 3D volume data, the color of each pixel in the image is typically obtained by accumulating the contributions of sample points on the ray cast from the pixel point. This accumulation is most naturally represented by integration. In most methods, however, it is done by numerical summation because analytical solution to the integration are hard to find. This paper shows that a semi-analytical solution can be obtained for a typical ray tracing of volume data. Tentative conclusions about the significance and usefulness of our approach are presented based on our experiments.

• Journal of Korea Multimedia Society
• /
• v.9 no.9
• /
• pp.1160-1172
• /
• 2006

Unfolding is an efficient technique to detect colorectal disease since it represents entire shape of colon at a glance. However, the previous unfolding methods may miss the surface located behind the folds or high curvature areas. To solve the problem, we propose an adaptive unfolding method that controls the number of rays in accordance with the surface complexity. In the first step, we find sample points of longer and shorter distance between the sample points and the colon surface, and then determine them as based control points. Next, for reaching rays of sample points in the wrinkled colon surface, sample points are shifted toward the control points that have the long distance. Lastly, we perform a 2D scaling which solves local distortions of the unfolding surface and avoids missing surface. Consequently, our method could be visualized the hidden surface of colon organ in detail.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.875-878
• /
• 2010

In this paper, we proposed a RSSI based cooperative localization algorithm considering wireless propagation characteristics in indoor environment for wireless sensor networks, which can estimate the BN position. The conventional RSSI based estimation scheme has low precision ranging according to time variable propagation characteristics. Hence, we implemented ray-launching simulator for analysis of propagation characteristics in $13.65m{\times}8.7m$, and performed proposed localization scheme with 4 RN and 1 to 5 BN. From the results, if we can consider channal characteristic in proposed ranging scheme, the cooperative localization algorithm with propagation characteristics provides higher localization accuracy than RSSI based conventional one.