• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.528-530
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• 2003

We present a novel photo-addressable electronic paper using an electrophoretic device, which can show and sustain the 2D images transferred by the UV illumination. The device consists of the organic photoconducting layer reacting with the UV illumination and the electronic ink (white particles and blue dye) dispersing in a suspending medium. The voltage impression under illuminating of UV make an image be transferred to the electrophoretic cell. The transferred image can be maintained by the bistability of the electrophoretic device.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.555-558
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• 2003

The bistability in a chiral-splay nematic liquid crystal cell, which is obtained by adding a chiral additive to a splay cell, is proposed. In this paper, we describe a new horizontal way of switching between the two states of the bistable chiral-splay cell, one state being characterized by a non-twisted director field with splay, the second state showing a director-field with $180^{\circ}C$ twist.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04b
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• pp.109-111
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• 2002

We have demonstrated all-opticalflip-flop based on optical bistability in a SOA/DFB-SOA with broadband gain. Input signal with the wavelength of 1340.23 nm or 1680.93 nm and the current of about 98% of the lasing threshold is injected into theDFB-SOA. Current injected into SOA is 80 mA All-optical flip-flop has various applications such as all-optical memory, demultiplexing, packet-header buffering, and retiming.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.379-382
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• 2006

We are investigating the effect of particle on electrowetting, and this paper reports the experimental results obtained until now. The experiment was performed for different particle sizes, electrolyte concentration, and AC frequencies. The problem is quite complicated by various factors, such as the existence of surfactant in suspension and sedimentation of particles. We could not draw a concrete conclusion on the effect of particles, and it needs further investigations. We also report interesting phenomena observed during the experiment. It includes the droplet generation at the edge of a droplet, pseudo-bistability of electrowetting, flow generation inside a droplet, and the chain formation of particles inside a droplet.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.5
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• pp.617-624
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• 2007

This paper presents a novel quadstable monolithic mechanism (QsMM) which provides four stable equilibrium positions within its operation range. The quadstable mechanism has been realized from the use of both X- and Y-directional bistable structures which use curved snapping beams. A millimeter-scale brass mechanism was fabricated by ultra-precision milling to test the quadstability and the displacement-load behavior, and the prototype clearly demonstrated four distinct stable positions in its millimeter-scale planar operation. We discuss the design concept, finite element simulation for static and transient responses, fabrication by ultra-precision milling, and experimental measurement of the proposed quadstable mechanism.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.187-190
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• 2005

Alignment pattern of checkerboard was constructed by the stylus of atomic force microscope. Orientational bistability of the nematic liquid crystal was realized on that frustrated surface alignment. Macroscopic orientational switching between two perpendicular directions took place by an appropriate in-plane electric field. The threshold electric fields decreased in both switching directions as temperature increased. The focused laser heated up only the limited domains in the cell including a light-absorbing medium. Irradiating the laser concurrently with an appropriate electric field, we switched the selected unit domains in the alignment pattern. The switched domains maintained stably the switched direction without the disturbance from the exterior. Extending and repeating this process, we realized extremely fine devices of bistable switching.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.387-391
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• 1987

We have observed the optical bistabilities at $5145{\AA}$ in nonlinear etalons filled with NOA8l optical adhesive which is cured with UV light under the temperature gradient of $7^{\circ}C/mm$ on the NOA81 layer surface. The critical switch-on irradiance and switch-on time are $17\;KW/cm^2$ and $350{\mu}sec$. respectively. The switching contrast of up to 8 observed in NOA81 etalons is higher than that of ZnS or ZnSe interference filter, and the thermo-optic coefficient (dn/ndT) of NOA81 is measured to be at least $-3.8{\times}10^{-4}/^{\circ}C$ which is larger in magnitude than that of ZnS or ZnSe.

• Journal of Information Display
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• v.4 no.1
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• pp.1-8
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• 2003

Recent progress in both low pretilt and high pretilt defect free C1 surface stabilized ferroelectric liquid crystal (SSFLC) devices is reviewed. First, by numerical calculation to investigate the balance between surface azimuthal anchoring energy and bulk elastic energy within the confined chevron layer geometry of C1 and C2, it is possible to achieve a zigzag free C1 state by low azimuthal anchoring alignment with a low pretilt angle. The critical azimuthal anchoring coefficient for defect free C1 state is calculated. Its relationship with elastic constant, chevron angle as well as surface topography effect are also discussed. Second, using $5^{\circ}$ oblique SiO deposition alignment method a defect free, large memory angle, high contrast ratio and bistable C1 SSFLC display, which has potential for electronic paper applications has also been developed. The electrooptical properties and bistability of this device have been investigated. Various aspects of defect control are also discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.474-480
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• 2008

In order to make full color cholesteric displays, color filter-less R, G, B sub-pixel structured cholesteric LC cells have been studied. To make R, G, B colors, UV induced pitch variant chiral dopant was added to cholesteric LC mixtures. The concentration of the photo-sensitive chiral dopant was adjusted so that the initial state showed blue color and the color was changed from blue to green and red with increase of UV irradiation to the cholesteric cells. To prevent the mixing of R, G, B reflective sub-pixel liquid crystals, separation walls were formed using negative photo resister in boundary area between sub-pixels, Through the optimization of the material concentrations and UV irradiation condition, vivid R, G, B colors were achieved.

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.212-216
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• 2016

A reflective electronic display that uses negatively and positively charged particles has excellent bistability, a welldefined threshold voltage, and an extremely fast response time in comparison with other reflective displays. This type of display shows images through the movement of charged particles whose motion depends on the value of q/m (charge per mass for a particle). However, the ratio q/m can easily be changed by the forces acting on the charged particles in a cell of the panel and by friction that occurs after mixing oppositely charged particles and in the particle-insertion process. In this study, we propose a method to determine the appropriate range of q/m by using the reflectivity and response time of charged particles to modify q/m. In this manner, the electrical and optical properties of reflective displays are improved.