Soon-gi Park

Effects of Recombinant Dentin Sialoprotein in Dental Pulp Cells

Dentin sialophosphoprotein (DSPP) is critical for dentin mineralization. However, the function of dentin sialoprotein (DSP), the cleaved product of DSPP, remains unclear. This study aimed to investigate the signal transduction pathways and effects of recombinant human DSP (rh-DSP) on proliferation, migration, and odontoblastic differentiation in human dental pulp cells (HDPCs). The exogenous addition of rh-DSP enhanced the proliferation and migration of HDPCs in dose- and time-dependent manners. rh-DSP markedly increased ALP activity, calcium nodule formation, and levels of odontoblastic marker mRNA. rh-DSP increased BMP-2 expression and Smad1/5/8 phosphorylation, which was blocked by the BMP antagonist, noggin. Furthermore, rh-DSP phosphorylated extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), Akt, and IκB-α, and induced the nuclear translocation of the NF-κB p65 subunit. Analysis of these data demonstrates a novel signaling function of rh-DSP for the promotion of growth, migration, and differentiation in HDPCS via the BMP/Smad, JNK, ERK, MAPK, and NF-κB signaling pathways, suggesting that rh-DSP may have therapeutic utility in dentin regeneration or dental pulp tissue engineering.

3D/2D convertible projection-type integral imaging using concave half mirror array

We propose a new method for implementing 3D/2D convertible feature in the projection-type integral imaging by using concave half mirror array. The concave half mirror array has the partially reflective characteristic to the incident light. And the reflected term is modulated by the concave mirror array structure, while the transmitted term is unaffected. With such unique characteristic, 3D/2D conversion or even the simultaneous display of 3D and 2D images is also possible. The prototype was fabricated by the aluminum coating and the polydimethylsiloxane molding process. We could experimentally verify the 3D/2D conversion and the display of 3D image on 2D background with the fabricated prototype.

Analysis of Image Visibility in Projection-type Integral Imaging System without Diffuser

We analyze image visibility of a projection-type integral imaging system without diffuser, in terms of the fill factor, which is determined by the relationship between the exit pupil of the projection system and the size and the focal length of the elemental lens. High fill factor is a requirement for good visibility. Moreover, for psychological reasons, for the same fill factor, better visibility is accomplished using a relatively small elemental lens. In this paper, we study image visibility through basic experiments and results.

Recent issues on integral imaging and its applications

In this review paper, the recent progress of 3D applications using integral imaging is introduced. Thanks to the progress of the flat panel displays, the quality of the 3D displays has also improved, resulting in the opening of more applications of the 3D display. The previous studies on integral imaging emphasized the improvement of the viewing quality of the integral imaging system, but the emergence of new technologies requires more than the replacement of the current 2D displays. New applications of the integral imaging method, such as displays with augmented reality, 3D information capturing, real-time processing, the projection-type method, and the integral floating method, and their recent research trends, are introduced.

Projection-type integral imaging system using multiple elemental image layers

A projection-type integral imaging system is proposed using multiple elemental image layers obtained from a single projector. In a conventional projection-type integral imaging system, only one display mode among real, virtual, and focused modes can be displayed selectively with a single projector. Plural projectors must be used for the generation of multiple elemental image layers. However, in the proposed method, the real and the virtual modes can be displayed simultaneously by generating multiple elemental image layers within the depth of field of a single projector. To embody the proposed method, the system specifications, such as the focal lengths of lenses and the distance between components, must be designed carefully. In this paper, we define and calculate the system factors and present the design role of the system. The feasibility of the proposed method is demonstrated with experimental results.

Coriandrum sativum L. Protects Human Keratinocytes from Oxidative Stress by Regulating Oxidative Defense Systems

Background: Oxidative radicals are major environmental causes of human skin damage. Oxidative defense factors, including nuclear factor erythroid-derived 2-related factor 2 (Nrf2), are centrally involved in repairing skin cells or protecting them from oxidative damage. Coriandrum sativum L. (coriander; CS) is a commonly consumed food and a traditional phytomedicine in Asia and Europe. In this study, we examined the protective effects of a standardized CS leaf extract against oxidative stress in human HaCaT keratinocytes. Methods and Results: CS significantly and dose-dependently protected cells against reduced cell viability caused by H2O2-induced damage, as assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Other assays demonstrated that CS protected HaCaT cells by increasing the levels of glutathione and activities of oxidative defense enzymes, such as superoxide dismutase and catalase. Moreover, it increased the expression of activated Nrf2, which plays a crucial role in protecting skin cells against oxidative stress. Conclusion: These results suggest that CS protects human keratinocytes from H2O2-induced oxidative stress through antioxidant effects.

Integral imaging system using a dual-mode technique

A new integral imaging system is proposed that uses a dual-mode technique, in which the elemental lens of the lens array is used not only as a convex lens but also as a convex mirror. The integral imaging system using dual modes can represent the real and the virtual integrated images simultaneously with improved viewing parameters. The lens array coated with thin aluminum is used to balance the ratio between the reflectance and the transmittance of lens array. The feasibility of the proposal is proved by the experiments.

Resolution enhancement of holographic printer using a hogel overlapping method

We propose a hogel overlapping method for the holographic printer to enhance the lateral resolution of holographic stereograms. The hogel size is directly related to the lateral resolution of the holographic stereogram. Our analysis by computer simulation shows that there is a limit to decreasing the hogel size while printing holographic stereograms. Instead of reducing the size of hogel, the lateral resolution of holographic stereograms can be enhanced by printing overlapped hogels, which makes it possible to take advantage of multiplexing property of the volume hologram. We built a holographic printer, and recorded two holographic stereograms using the conventional and proposed overlapping methods. The images and movies of the holographic stereograms experimentally captured were compared between the conventional and proposed methods. The experimental results confirm that the proposed hogel overlapping method improves the lateral resolution of holographic stereograms compared to the conventional holographic printing method.

Integral imaging using a color filter pinhole array on a display panel

We propose methods of enhancing pinhole-type integral imaging ray density, resolution, and expressible depth range using a color filter pinhole array on a liquid crystal display panel with a projection scheme. A color filter structure on a liquid crystal display panel acts as pinhole array in integral imaging with separation of color channels. In conventional pinhole-type integral imaging, the resolution, viewing angle, and ray density are limited by the pinhole interval, the width and thickness of the pinhole structure, and the gap between the display panel and the pinhole array. To overcome the limitation of the pinhole interval, we use a color filter pinhole array on a display panel and a projection-type integral imaging scheme. The use of a color filter pinhole array and the projection scheme can enlarge the region of one elemental image and improve the resolution and ray density remarkably. This paper presents the experimental results of the proposed method and a comparison with conventional methods.

Depth-expression characteristics of multi-projection 3D display systems [invited].

A multi-projection display consists of multiple projection units. Because of the large amount of data, a multi-projection system shows large, high-quality images. According to the projection geometry and the optical configuration, multi-projection systems show different viewing characteristics for generated three-dimensional images. In this paper, we analyzed the various projection geometries of multi-projection systems, and explained the different depth-expression characteristics for each individual projection geometry. We also demonstrated the depth-expression characteristic of an experimental multi-projection system.