라이트페인팅기법을 활용한 창작 헤어아트 제작 연구

조영민(Young-Min Cho),박은준(Eun-Jun Park) 한국인체미용예술학회 2021 한국인체미용예술학회지 Vol.22 No.2

In the early stages of hair art, up-styles were created using a mannequin or a model, and waste hair was mainly used. Recently, however, diverse hairstyles have been developed using a hybrid approach through the reanalysis of paintings and formative art styles. In addition, various materials have been adopted. Even though some previous hairstyles have used light painting, it has recently been more recognized as a tool. This study attempted to create light-painting styles, using light painting as an object, not as a tool. For this, long-exposure photography was employed. The goal was to use a light-painting technique, which itself becomes a work, not to suggest a style through photography. Among many light-painting tools, 3 tools with which diverse styles were expressed with light: Pixelsticks, optical fibers, and light panels. Then, hairstyling methods were attempted by creating abstract hair works through light-based light painting. In this study, a total of 8 different hairstyles were created to suggest new styling methods, using light painting under 8 different circumstances. Light painting can be expressed with dots, lines, and planes. This study adopted 3 tools: Pixelsticks, optical fibers, and light panels. These tools offer diverse colors and options, such as brightness control, thereby enabling various expressions. This study created hairstyles through light painting. It is anticipated that hairstyling techniques would become more diverse and further evolve, using a wide variety of materials.

광대역 가시광 차단을 위한 윈도우 셔터

최규진,정혜민,곽진석 한국물리학회 2017 새물리 Vol.67 No.3

본 논문에서는 특정한 피치를 갖는 콜레스테릭 액정의 플라나 상태 (Planar state)가 브래그 (Bragg) 반사에 의해 입사한 빛의 특정 영역의 파장을 반사시키며, 온도가 전이온도 이상이 되면 등방상태 (isotropic state)가 되어 모든 영역의 빛을 투과시키는 특성을 이용하여, 가시광선을 반사하고 투과하는 전기적 윈도우 셔터를 제안한다. 가시광선 전 영역의 넓은 파장 폭에서 반사가 이루어 지도록 하기 위한 시도로써, 온도에 따라 콜레스테릭 액정의 피치가 변하는 성질과 고분자 광경화제가 섞인 액정이 자외선 조사에 의해 고분자 네트워크에 의해 피치가 고정되는 성질을 이용하기 위하여 콜레스테릭 액정에 경화성액정 (reactive mesogen, RM)을 적절히 섞어 셀에 주입하였고 셀 내부에 온도를 스텝 별로 변화 시키면서 자외선을 콜레스테릭 액정 셀에 조사하였다. 이는 셀 내부에 가시광선 영역을 덮는 다양한 피치를 생성시켜 광대역 반사를 이끌어낸다. 이러한 방법으로 제작된 콜레스테릭 액정 셀은 전 가시광영역(450$\sim$650 nm)에서 빛을 차단하고 투과할 수 있음을 확인하였다. We present an electrical window shutter with cholesteric liquid-crystal cells. That shutter is by using the properties that a cholesteric liquid crystal (CLC) having a specific pitch reflects specific wavelengths of incident light in the planar state and turns into the isotropic state when its temperature becomes higher than the transition temperature. In an attempt to attain the reflection in a wide-band range of the visible region, we use the properties that the pitch of the CLC changes with the temperature and the pitch of a liquid crystal with a photo-curable polymer is fixed by exposure to UV light. In detail, a cholesteric liquid crystal with reactive mesogen as a UV light curable polymer is injected into a cell, and the cholesteric cell is exposed continuously to UV light while changing the temperature of the cell in steps. This leads to the production of various pitches in the cell, thus generating wide-band reflections in the visible region. We confirmed that the cholesteric cell fabricated by using such a process shows wide-band reflections in the visible region and blocks visible light by working as a window shutter.

Ion-doped liquid-crystal cell with low opaque-state specular transmittance based on electro-hydrodynamic effect

Huh, Jae-Won,Kim, Jin-Hun,Oh, Seung-Won,Ji, Seong-Min,Yoon, Tae-Hoon Elsevier 2018 Dyes and pigments Vol.150 No.-

<P><B>Abstract</B></P> <P>We demonstrate an ion-doped liquid-crystal (LC) cell that can provide a very low specular transmittance in the opaque state using the electro-hydrodynamic effect. In the opaque state, the LC and dye molecules are oriented randomly in planes parallel to the substrates because of the electrohydrodynamic effect. We found that the total transmittance of an ion-doped LC cell is almost the same as that of a light shutter based on light absorption and its haze value is the same as that of a light shutter based on light scattering. Moreover, an ion-doped LC cell can be fabricated without an ultraviolet curable process. Owing to its excellent opaque state properties, an ion-doped LC cell can be used in see-through display and smart-window applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We demonstrate an LC cell that can provide a very low total transmittance. </LI> <LI> For opaque state, we use negative LC with dye and electro-hydrodynamic effect. </LI> <LI> Most of the dye molecules are oriented parallel to the substrates. </LI> <LI> Randomly distributed negative LCs with small domains scatter the incident light. </LI> <LI> It can be fabricated without an ultra-violet curing process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Microcavity characteristics analysis of micro-shuttered organic light-emitting diodes

Lee, Dong Jun,Park, Soo Jong,Park, Cheol Hwee,Park, Young Wook,Ju, Byeong-Kwon Elsevier S.A. 2019 Thin Solid Films Vol.692 No.-

<P><B>Abstract</B></P> <P>We demonstrated the control of the microcavity (MC) effect in micro-shuttered organic light-emitting diodes (OLEDs) with the introduction of an Ag striped pattern (ASP) layer between the organic layer and the indium zinc oxide layer. The ASP electrodes demonstrated high flexibility, conductivity, and transmittance. The optical and electrical properties of the OLED devices with micro-scale patterned metal electrodes with varying thicknesses and uncovered (open) area:entire glass surface area ratios (open ratios, ORs) were analyzed. The ASP OLEDs demonstrated high color purity and narrowed emission spectra because of the MC effect, increased light extraction by modulating the OR of the micro-shutter structure, and adjustability of the viewing angle distortion by controlling the OR. The ASP OLEDs exhibited maximum efficiency at the OR of 0.3 (Ag thickness; t<SUB>Ag</SUB> = 15 nm) because of their optimum transmittance and conductivity. The viewing angle distortion decreased by approximately 60.3% with an increase in the OR from 0 to 0.7, as revealed by the changes in the color coordinates. The results showed that when deposited on flexible substrates, ASP electrodes can be used in flexible devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The microcavity effect via Ag striped pattern electrodes was profoundly analyzed. </LI> <LI> The electroluminescence characteristics were improved by Ag striped pattern electrodes. </LI> <LI> The device with Ag striped pattern electrodes can be used in flexible devices. </LI> </UL> </P>

Ambient Light Backscatter Communication for IoT Applications

Jisu Yun,Byung-Jun Jang 한국전자파학회JEES 2016 Journal of Electromagnetic Engineering and Science Vol.16 No.4

In this paper, we present an ambient light backscatter communication design that enables Internet of Things (IoT) devices to communicate through the backscattering ambient light emitted from lighting infrastructure or sunlight. The device can selectively modulate ambient light by switching a liquid crystal display (LCD) shutter located on its surface, so that a nearby smart device, which includes a photodiode or a camera, can demodulate this backscattered light information. To verify the practicality of the proposed concept, we design an IoT device equipped with a commercial LCD shutter and a microcontroller. Our device produces ambient light backscattered data at a speed of 100 bps, and these data are successfully decoded by a commercial photodiode module 10 cm away from the IoT device. We believe that our ambient light backscatter communication design is appropriate for implementation in various IoT applications.

Visible light communication based vehicle positioning using LED street light and rolling shutter CMOS sensors

Do, T.,Yoo, M. North-Holland Pub. Co 2018 OPTICS COMMUNICATIONS - Vol.407 No.-

This paper proposes a vehicle positioning system using LED street lights and two rolling shutter CMOS sensor cameras. In this system, identification codes for the LED street lights are transmitted to camera-equipped vehicles through a visible light communication (VLC) channel. Given that the camera parameters are known, the positions of the vehicles are determined based on the geometric relationship between the coordinates of the LEDs in the images and their real world coordinates, which are obtained through the LED identification codes. The main contributions of the paper are twofold. First, the collinear arrangement of the LED street lights makes traditional camera-based positioning algorithms fail to determine the position of the vehicles. In this paper, an algorithm is proposed to fuse data received from the two cameras attached to the vehicles in order to solve the collinearity problem of the LEDs. Second, the rolling shutter mechanism of the CMOS sensors combined with the movement of the vehicles creates image artifacts that may severely degrade the positioning accuracy. This paper also proposes a method to compensate for the rolling shutter artifact, and a high positioning accuracy can be achieved even when the vehicle is moving at high speeds. The performance of the proposed positioning system corresponding to different system parameters is examined by conducting Matlab simulations. Small-scale experiments are also conducted to study the performance of the proposed algorithm in real applications.

Light shutter using dye-doped cholesteric liquid crystals with polymer network structure

유병훈,지성민,김진훈,허재원,윤태훈 한국정보디스플레이학회 2017 Journal of information display Vol.18 No.1

Proposed herein is a light shutter using dye-doped cholesteric liquid crystals with a polymer network structure for a high-visibility see-through display. The proposed light shutter shows an initially focal-conic state by forming the polymer network structure at the focal-conic state. The proposed light shutter can be easily switched between the focal-conic and homeotropic states without a complicated drive scheme.

가시광의 후방산란을 이용한 VLID 시스템 설계 및 구현

윤지수(Jisu Yun),장병준(Byung-Jun Jang) 한국전자파학회 2017 한국전자파학회논문지 Vol.28 No.1

본 논문에서는 LCD(Liquid Crystal Display) 셔터로 입사된 가시광의 후방산란 특성을 변화시켜 태그의 ID 정보를 리더로 전달하는 VLID(Visible Light Identification) 시스템을 설계 및 구현하였다. 구현된 VLID 시스템은 RFID(Radio Frequency Identification)의 원리를 가시광 통신에 적용한 것으로, 태그 표면에 부착된 LCD 셔터를 이용하여 태그의 정보에 따라 VLID 리더에서 송신한 빛을 선택적으로 후방산란시키고, 이 변화를 리더가 인식하도록 한다. VLID 태그는 마이컴과 태그 표면에 부착된 LCD 셔터로 구성되며, VLID 리더는 6개의 LED, 그 중심에 놓여있는 하나의 photodiode, 관련 아날로그 회로 및 블루투스(bluetooth)를 통한 PC 인터페이스로 구성된다. 실험 결과, 낮 기준으로 35 ㎝ 이상의 거리에서 100 bps 속도로 단극성 NRZ-OOK(Non Return to Zero ON/OFF Keying) 변조한 태그의 정보를 성공적으로 인식할 수 있었다. 또한, 이론적인 최대 전송속도, 인식거리 개선 방법 등을 제안하였다. In this paper, we designed and implemented a visible light identification(VLID) system consisting of a VLID reader and a tag which backscatters incident lights from the reader. A VLID tag sends its ID to the reader by switching an LCD shutter which is located on its surface. The VLID reader consists of six LEDs and a photodiode(PD). The LEDs emit visible light and a PD located in a center position of LEDs receives backscattered light from the VLID tag. A microcontroller and a commercial liquid crystal display(LCD) shutter for 3D-TV glasses are used to implement a VLID tag. Experiments were conducted to confirm VLID system performance. We successfully demonstrated experiments to send NRZ-OOK signal of 100 bps over a distance of 35 ㎝ at daytime. Also, we suggested the theoretical maximum transmission rate and the various methods to enhance the separation distance between a VLID reader and a tag.

2P-311 Benzene-1,3,5-Tricarboxamide Macrogelator for Stimuli-Responsive Light Shutter

최유진,정광운 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

To fabricate the rewritable electro-optic devices, we newly synthesized the macrogelator of a benzene-1,3,5-tricarboxamide (BTA)-based macrogelator (abbreviated B9AZ). By means of liquid crystalline physical gelation (LCPG) process, the programmed B9AZ macrogelator in the NLC medium built up three-dimensional networks not only by hydrogen-bonding between BTA cores but also by nanophase separations between B9AZs and NLCs. On the basis of the anisotropic optical properties of LCPGs, it was realized that a light scattering state of B9AZ LCPGs can be switched to a transmittance state under a fairly low driving voltage (22 V) compared with those of polymer-based systems. Additionally, the B9AZ LCPGs can be remote-controlled by utilizing the trans-cis photoisomerization of the azobenzene moieties in the LCPGs. ^**This work was supported by the Mid-Career Researcher Program (2016R1A2B2011041) and Global Ph. D. Fellowship Program (NRF-2016H1A2A1907561) of Korea.

Fabrication of an initially-focal-conic cholesteric liquid crystal cell without polymer stabilization

Baek, Jong-Min,Oh, Seung-Won,Kim, Sang-Hyeok,Yoon, Tae-Hoon Elsevier 2018 Displays Vol.52 No.-

<P><B>Abstract</B></P> <P>A dye-doped cholesteric liquid crystal (LC) cell with the focal-conic initial state is demonstrated. Although dye-doped LC/polymer composites have been widely used for LC light shutters, dye-doped LC cells with polymer structures suffer from the degradation of dichroic dyes during the UV curing process. To avoid this problem, we propose a dye-doped cholesteric LC cell using vertical alignment layers instead of polymer structures. We have shown that the focal-conic initial state can be obtained by homeotropic anchoring without the polymer structure. The proposed device not only provides the black color but can also hide objects behind a display panel in the focal-conic initial state without the degradation of dichroic dyes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We propose a dye-doped cholesteric LC cell using vertical alignment layers. </LI> <LI> The proposed device provides black color and hides objects behind a display panel. </LI> <LI> The focal-conic initial state can be obtained without the degradation of dyes. </LI> </UL> </P>