• Korean Journal of Cognitive Science
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• v.15 no.4
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• pp.1-14
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• 2004

When two objects are tying in the same visual direction there occurs abrupt depth change between two objects, which is against the assumption of the computational model for stereopsis on the surfaces in a natural scene. For this reason, this stimulus configuration is popularly used in the studies for the effectiveness of the constraints employed in the computational model. Contrary to the results from two nails (or objects) tying in the same visual direction, the two different surfaces from random-dot stereogram (RDS) in the same situation can be seen simultaneously in the different depth. The seemingly contradictory results between two situations my reflect the different strategies imposed by binocular mechanism for each situation during binocular matching process. Otherwise, the surfaces tying in the same visual direction is not equivalent situation to two objects tying in the same visual direction with regards to matching process. In order to examine above possibilities, the stereoscopic depth of the surface was measured after manipulating the visual direction of the surface elements. The visual direction of each dot pair from different surfaces in RDS (in Experiment 1) or the visual direction of line (hawing rectangle with regard to that of the vertical line (in Experiment 2) was manipulated. The stereoscopic depth of the surface was found to be varied depending on visual direction of the surface elements in both RDS and line hawing stimulus. Similar to the results from two nails situation depth of the surface was greatly reduced when each surface element was tying in the same visual direction as that of the other surface element or the other object. These results suggest that binocular mechanism imposes no different strategy in resolving correspondence problem in both two objects and two surfaces situation. And the results were discussed in the context of usefulness of the constraints employed in the computational model for stereopsis.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.381-386
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• 2008

Virtual 3D audio methods that create 3D sound effects are researched highly for multimedia devices using 2 speakers or headphone. The most typical method to create 3D effects is a technology through use of head related transfer function (HRTF) which contains the information that sound arrives from a sound source to the ears of the listener. But it can decline some 3D effects by cone of confusion between front and back directions due to the non-individual HRTF depending on each listener. In this paper, we propose a new method to use psychoacoustic theory that creates realistic 3D audio. In order to improve 3D sound, we calculate the excitation energy of each symmetric HRTF and extract the ratio of energy of each bark range. Informal listening tests show that the proposed method improves the front-bach sound localization characteristics much better than the conventional methods.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.279-282
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• 2009

본 논문에서는 행렬응축기법 및 부구조기법을 이용하여 가변형 입체 복합 공간 구조물을 효율적으로 해석할 수 있는 해석기법을 제안하였다. 최근 구조공학의 발전과 더불어 다양한 사회적 경제적 요구에 의해 가변형 입체 복합 공간 구조물에 대한 연구가 진행되고 있다. 가변형 입체 복합 공간 구조물은 많은 구조부재가 필요 하며, 부재 수가 많아짐에 따라 각 절점이 가지는 자유도수가 크게 증가하여 초기 해석 과정에서 많은 시간이 요구된다. 또한 구조물이 변경되는 경우에는 변경되는 부분의 강성의 변화에 따라 전체 구조물의 강성이 변경되므로 이에 따른 전체 구조물의 재해석 과정이 필요하다. 이러한 점에서 구조물의 자유도수를 줄여주는 행렬응축기법과 반복적인 해석과정을 줄여주는 부구조기법은 가변형 입체 복합 공간구조물을 효율적으로 해석 할 수 있는 방법이 될 수 있다. 본 논문에서는 행렬응축기법과 부구조기법을 이용하여 가변형 입체 복합 공간 구조물을 효율적으로 해석할 수 있는 해석기법을 제안하고, 이를 토대로 구체적인 알고리즘을 작성하였다. 또한 알고리즘을 구체화시켜 가변형 입체 복합 공간 구조시스템에 적합한 구조해석 프로그램을 개발하여 예제 구조물에 대하여 구조해석을 수행하였으며, 구조해석 결과를 상용프로 그램의 구조해석 결과와 비교하여 해석기법에 대한 정확성 및 효율성을 검토하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.236-237
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• 2003

3차원 영상표시를 위한 방법은 여러 가지 방향에서 연구되어 왔다. 이중 홀로그램을 이용한 방법은 완벽한 3차원 영상을 표현할 수 있지만 스페클 잡음이 나타나고 시야각이 제한되며 단색 간섭성 광원을 사용해야하는 등의 문제점이 있어 실제 응용에 제한을 받고 있다. 이에 따라 최근 들어 쌍안 방식을 포함한 3차원 입체영상의 구현을 위한 다양한 연구가 활발하게 수행되고 있다. 렌즈 어레이를 이용한 집적결상의 방법도 그 중의 하나로 완벽한 색상의 구현, 연속적 시야각 확보, 단순한 광학계에서 구현가능 등의 장점이 있어 응용 가능성이 매우 높은 방법 중 하나로 평가되고 있다. (중략)

• The Journal of the Acoustical Society of Korea
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• v.30 no.4
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• pp.181-189
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• 2011

According to developments of digital signal processing, 3D sound come into focus on multimedia systems. Many studies on 3d sound have proposed lots of clues to create realistic sounds. But these clues are only focused on binaural systems which two ears are normal. If we make the 3d sound using those clues at monaural systems, the performance goes down dramatically. In order to use the clues for monaural systems, we have studies algorithms such as duplex theory. In duplex theory, the sounds that we listen are affected by human's body, pinna and shoulder. So, we can enhance sound localization performances using its characteristics. In this paper, we propose a new method to use psychoacoustic theory that creates realistic 3D audio at monaural systems. To improve 3d sound, we calculate the excitation energy rates of each symmetric HRTF and extract the weights in each bark range. Finally, they are applied to emphasize the characteristics related to each direction. Informal listening tests show that the proposed method improves sound localization performances much better than the conventional methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.575-578
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• 2001

원격 조작이나 해저 수중 탐사에서 실제와 같이 거리감을 인식하며 제어하기 위하여, 3차원 입체 영상 카메라 장치를 사용하고 있다. 기본적인 구성 형태인 Stereoscopic Camera 시스템은 기구적으로 주시각 제어와 초점 제어가 이루어 지고 있으며, 획득영상에 대하여 영상 distortion 보정, 압축 처리 등의 영상 신호처리가 행하여진다. 양안 카메라의 수평 위치를 일치시켜 수평적으로 동일 위치의 pixel들이 정확한 epipolar line을 형성할 경우에, 주시각 제어가 용이하고 보정 및 영상처리 등의 연산량이 대폭 감소된다. 이와 같은 calibration 과정을, 기존의 시스템에서는, 주로 영상 획득 포기에 패턴을 사용하여 실시하거나, 물리적 수평 장치와 sensor 등의 보조 장치를 이용하여 calibration을 행한다. 그러나, 기계적으로 정밀하게 정렬을 한다고 하여도 두 카메라의 광축 및 CCD조립상 상이점과 특성의 불일치로 인하여 실제 획득된 영상에서는 변이와 회전이 포함된 영상을 얻게된다. 본 논문에서는 Stereoscopic Camera의 위와같은 정렬 오류의 문제점을 분석한 후, 제안 방식으로서 두 카메라의 획득되는 영상을 직접 영상 처리하여 수직 방향 및 회전 오류를 최소화 시켜 정렬하는 새로운 방법을 제시하며, 실험적으로 제안 방식의 효율성을 보인다.

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.33-41
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• 2010

It is stated in the highway geometric design guide that expressway interchange types should be selected considering a set of input variables including travel demand, topography, construction cost and interchange spacing. However, this selection method has a problem of providing different interchange types even for the same input variables depending upon different applications of engineers discretion. A procedure that produces consistent results is necessary and this paper presents the development of an efficient and reliable procedure based on the quantification of road user costs and construction costs on interchanges. To develop this procedure, a survey of existing expressway interchange types in South Korea was made and 10 basic interchange types and 52 supplementary interchange types were identified. To relate road user costs and construction costs to these interchange types, this research uses two method. First, interchange types were expressed by a set of ramp configurations. Second, road user benefits and construction costs associated with these different interchange types were formulated based on the current national guide of the expressway economical analysis. As a result, it was proved that an interchange type to provide minimum costs could be selected consistently and this research result should be useful for future expressway geometric designs.

• Radiation Oncology Journal
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• v.14 no.2
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• pp.149-158
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• 1996

Purpose : To get an accute steepness of dose gradients at outside the target volume in intracranial lesion and a less limitation of beam selection avoiding the high dose at normal brain tissue, this Photon Knife Radiosurgery System was developed in order to provide the three-dimensional dose distribution through the reconstruction of CT scan and the combined stereotactic trans-multiarc beam mode based on linear accelerator photon beam. Materials and methods : This stereotactic radiosurgery, Photon Knife based on linear accelerator photon beam was provided the non-coplanar multiarc and trans-multiarc irradiations. The stereotactic trans-multiarc beam mode can be obtained from the patient position in decubitus. This study has provided the 3-dimensional isodose curve and anatomical structures with the surface rendering technique. The dose distribution from the combined two trans-multiarcs (2M 2TM) was compared to that of four non-coplanar multiarcs (4M) with same collimator size of 25 mm in a diameter and total gantry movements. Results : In this study, it shows that the dose distributions of stereotactic beam mode are significantly depended on the selected couch and gantry angle in same collimator size. Practical dose distribution of combined stereotactic trans-multiarc beam has shown a more small rim thickness than that of the non-coplanar multiarc beam mode in axial, sagittal and coronal plane in our study. 3-Dimensional dose line displayed with surface rendering of irregular target shape is helpful to determine the target dose and to predict the prognosis in follow-up radiosurgery. Conclusions : 3-Dimensional dose line displayed with surface rendering of irregular target shape is essential in stereotactic radiosurgery. This combined stereotactic trans-multiarc beam has shown a less limitation of the selection couch and gantry beam angles for the target surrounding critical organs. It has shown that the dose distribution of combined trans-multiarc beam greatly depended on the couch and gantry angles. In our experiments, the absorbed dose has been decreased to $27%$ / mm in maximum at the interval of $50\%$ to $80\%$ of isodose line.

• Korean Journal of Remote Sensing
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• v.18 no.2
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• pp.81-90
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• 2002

We carried out accuracy assessment for DEM extraction from the KOMPSAT-1 EOC stereo images over Daejeon and Nonsan in Korea. DEM generation divided into two parts. One is camera modeling and the other stereo matching. We used Orun & Natarajan's(1994) model and Gupta & Hartley's(1997) model in the camera modeling step and checked the possibility using Orun & Natarajan and Gupta & Hartley's models in EOC stereo pairs. For stereo matching, we used an algorithms developed in-house for SPOT images and showed that this algorithm could work with EOC images. Using these algorithms, DEMs were successfully generated from EOC images. The comparison of DEM from EOC Images with a DEM from SPOT Images showed that EOC could be used for high-accuracy DEM generation.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.477-484
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• 2015

Purpose: This study was investigated to evaluate the effect of the variation of the face form angle(FFA) of spectacle frame on the visual acuity and the visual function. Methods: The visual acuity, the contrast sensitivity, the stereopsis, and the phoria were measured with the spectacle frame whose the FFA is at $5^{\circ}$ and $25^{\circ}$ and the surveys were conducted on subjective symptoms. Here, 30 adults (14 men and 16 women, average age:$25.46{\pm}3.9$), who did not have ocular diseases and were fully corrected in case of having had refractive error, were to act as experimental subjects for this measurement. Results: The visual acuity and the contrast sensitivity was decreased and the phoria was tended to increase to the esophoria direction at the FFA $25^{\circ}$ than at the FFA $5^{\circ}$. The stereopsis was significantly reduced at the FFA $25^{\circ}$ than at the FFA $5^{\circ}$. Also when the FFA was larger, the higher the degree of refractive error was, the more the increase of the subjective symptoms such as being blurred characters, being disturbed head, and having sore eyes was, which reveals a statistically significant correlation between them. Conclusions: If the FFA increases, the visual acuity, the contrast sensitivity and the stereopsis was found to decrease and the phoria to increase to the esophoria direction. Therefore it shows that the variation of the FFA of spectacle frame can influence the visual acuity and the visual function.