Biomedical subjects

Yunhee Kim

Publications and source records attributed to Yunhee Kim.

7 recordsLinked to original sources

PubMed2006

Convertible two-dimensional-three-dimensional display using an LED array based on modified integral imaging.

We propose a two-dimensional (2D) to three-dimensional (3D) convertible display technique using a light-emitting diode (LED) array based on the principle of modified integral imaging. This system can be electrically converted between 3D and 2D modes by using different combinations of LEDs in the LED array without any mechanical movement. The LED array, which is controlled electrically, is used for backlight, and a lens array is used for making a point light source array with higher density. We explain the principle of operation and present experimental results.

Journal Article↗

PubMed2006

Depth-enhanced three-dimensional integral imaging by use of multilayered display devices.

Integral imaging is one of the promising three-dimensional display techniques and has many advantages. However, one disadvantage of integral imaging is the limited image depth. The image can be displayed only around the central depth plane. We propose a depth-enhanced integral imaging using multilayered display devices. We locate transparent display devices that use liquid crystal in parallel to each other and incorporate them into an integral imaging system. As a result, the proposed method has multiple central depth planes and permits the limitation of expressible depth to be overcome. The principle of the proposed method is explained, and some experimental results are presented.

Journal Article↗

PubMed2005

Improved analysis on the viewing angle of integral imaging.

There have already been several analyses about the viewing angle of integral imaging (InIm). However, they can be applied only under the assumption that the original image is merely a single point source and are not suitable for application to an actual condition. We propose an improved analysis based on the actual InIm image, not on a single point source. It is possible to analyze and predict the viewing angle of an InIm system with good accuracy with the new analytic method because almost all the parameters of the InIm system such as the size and focal length of the lens array, image distance, the size and resolution of the image, and the location of the observers are included in this analysis.

Algorithms↗

PubMed2005

Wide-viewing-angle integral three-dimensional imaging system by curving a screen and a lens array.

A wide-viewing-angle integral three-dimensional imaging system made by curving a screen and a lens array is described. A flexible screen and a curved lens array are incorporated into an integral imaging system in place of a conventional flat display panel and a flat lens array. One can effectively eliminate flipped images by adopting barriers. As a result, the implemented system permits the limitation of viewing angle to be overcome and the viewing angle to be expanded remarkably. Using the proposed method, we were able to achieve a viewing angle of 33 degrees (one side) for real integral imaging and 40 degrees (one side) for virtual integral imaging, which is four times wider than that of the currently used conventional techniques. The principle of the implemented system is explained, and some experimental results are presented.

Journal Article↗

PubMed2004

Depth-enhanced three-dimensional-two-dimensional convertible display based on modified integral imaging.

A depth-enhanced three-dimensional-two-dimensional convertible display that uses a polymer-dispersed liquid crystal based on the principle of integral imaging is proposed. In the proposed method, a lens array is located behind a transmission-type display panel to form an array of point-light sources, and a polymer-dispersed liquid crystal is electrically controlled to pass or to scatter light coming from these point-light sources. Therefore, three-dimensional-two-dimensional conversion is accomplished electrically without any mechanical movement. Moreover, the nonimaging structure of the proposed method increases the expressible depth range considerably. We explain the method of operation and present experimental results.

Equipment Design↗

PubMed2004

Depth extraction by use of a rectangular lens array and one-dimensional elemental image modification.

Stereo matching, a technique for acquiring depth information from many planar images obtained by several cameras, was developed several decades ago. Recently a novel depth-extraction technique that uses a lens array instead of several cameras has attracted much attention because of the advantages offered by its compact system configuration. We present a novel depth-extraction method that uses a lens array consisting of vertically long rectangular lens elements. The proposed method rearranges the horizontal positions of the pixels from the collection of perspective images while it leaves the vertical positions of the pixels unchanged. To these rearranged images we apply a correlation-based multibaseline stereo algorithm in properly modified form. The main feature of the proposed method is the inverse dependency of the disparity in depth between horizontal and vertical directions. This inverse dependency permits the extraction of exact depth from extremely periodically patterned object scenes and reduces quantization error in the depth extraction.

Journal Article↗

PubMed2004

Alterations in intracellular and extracellular activities of antioxidant enzymes during suspension culture of sweetpotato.

Cultured plant cells are a good system for the study of antioxidant mechanisms and for the mass production of antioxidants, because they can be grown under conditions of high oxidative stress. Alterations in the intracellular and extracellular activities of three antioxidant enzymes, superoxide dismutase (SOD), guaiacol-type peroxidase (POD), and glutathione peroxidase (GPX), were investigated in suspension cultures of sweetpotato (Ipomoea batatas) during cell growth. Intracellular SOD activities (units/mg protein) at 15 days after subculture (DAS) and 30 DAS were 10 and 20 times higher, respectively, compared with the SOD activity at 1 DAS, whereas intracellular specific POD and GPX activities did not significantly increase until after 15 DAS, when they rapidly increased. The extracellular activities of the three enzymes in culture medium were much higher than were the intracellular activities. The change in extracellular SOD activity was similar to that of extracellular GPX during cell growth. Those activities showed high levels until 5 DAS and then significantly decreased. Extracellular POD activity had an almost constant level regardless of the cell growth stage. In addition, intracellular SOD and POD isozymes were quite different from those isozymes in the culture medium. The changes in SOD and POD isozymes observed here suggest that different isozymes might modulate the levels of reactive oxygen intermediates during cell growth. Characterization of extracellular antioxidant enzymes discovered here would provide a new understanding for defense mechanism in plants.

Antioxidants↗