• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.986-990
• /
• 2002

Dual Mass Flywheel(DMF) is used in order to improve the vibration characteristics of drivetrain of manual transmission vehicles. Regardless of its complexity and high cost, application of DMF is keep increasing due to a trend of using Diesel engines in passenger cars and light weight design of drivetrains. Modeling and analysis of DMF is rather simple, but finding out optimum parameters of damper may not be easy. Furthermore, its realization in DMF has some limitations due to DMF's structure and its structure dependent damping characteristics. Requirements on spring-damper characteristics of DMF has been reviewed and investigations on structures and damping characteristics of currently Produced DMFs have been made in this paper. Also, ideal spring and damper characteristics has been proposed based on such investigations.

• Journal of the Optical Society of Korea
• /
• v.4 no.1
• /
• pp.48-53
• /
• 2000

In Optical Scanning Holography(OSH), 3-D holographic information of an object is generated by 2-D active optical scanning. The optical scanning beam can be a time-dependent Gaussian apodized Fresnel zone plate. In this technique, the holographic information manifests itself as an electric signal which can be sent to an electron-beam-addressed spatial light modulator for coherent image reconstruction. In this paper, we briefly review optical scanning holography and analyze the resolution achievable with the system. We also present mathmatical expressions of real and virtual images which are responsible for holographic image reconstruction. We then show the twin-image noise effect on the reconstruction in conjunction with the size of the Fresnel zone pattern through computer simulation.

• Korean Journal of Optics and Photonics
• /
• v.4 no.3
• /
• pp.330-337
• /
• 1993

Figure '8' type, passively-mode-locked erbium-doped-fiber ring laser was developed, incorporating a nonlinear loop mirror. Transmittance of the loop mirror was found to be dependent on the incident light intensity due to the non-reciprocal nonlinear phase shift, which enables the passive mode locking of the laser. Self-starting of stable mode locking was possible with only controlling the polarization controllers inside the cavity without any help of external perturbation or modulation. The mode-locked output pulse shape was discussed in relation with the transmission characteristics of nonlinear loop mirror.

• Molecules and Cells
• /
• v.26 no.3
• /
• pp.217-227
• /
• 2008

Heterochromatin protein 1 (HP1) was first described in Drosophila melanogaster as a heterochromatin associated protein with dose-dependent effect on gene silencing. The HP1 family is evolutionarily highly conserved and there are multiple members within the same species. The multi-functionality of HP1 reflects its ability to interact with diverse nuclear proteins, ranging from histones and transcriptional co-repressors to cohesion and DNA replication factors. As its name suggests, HP1 is well-known as a silencing protein found at pericentromeres and telomeres. In contrast to previous views that heterochromatin is transcriptionally inactive; noncoding RNAs transcribed from heterochromatic DNA repeats regulates the assembly and function of heterochromatin ranging from fission yeast to animals. Moreover, more recent progress has shed light on the paradoxical properties of HP1 in the nucleus and has revealed, unexpectedly, its existence in the euchromatin. Therefore, HP1 proteins might participate in both transcription repression in heterochromatin and euchromatin.

• Textile Coloration and Finishing
• /
• v.25 no.4
• /
• pp.262-270
• /
• 2013

Temporarily solubilized reactive disperse dyes containing ${\beta}$-sulfatoethylsulfonyl group were applied to 100% meta-aramid knitted fabric and their dyeing properties were investigated. Reactive disperse dyes showed relatively high K/S values on meta-aramid fabric when compared with conventional disperse dye or reactive dye, which showed very low K/S values. Color yields of reactive disperse dyes were highly dependent on dyeing pH and optimum results were obtained at pH 6. Percent exhaustion of reactive disperse dye on meta-aramid fabric was over 80% at 2% o.w.f of dye concentration. Wash fastness of pyridone-based reactive disperse dyes was very good to excellent while that of aminoazobenzene reactive disperse dyes was medium to good. Light fastness of all the reactive disperse dyes was very poor which seems to be due to the low photostability of meta-aramid fiber itself.

• Journal of Magnetics
• /
• v.18 no.2
• /
• pp.86-89
• /
• 2013

This paper shows a new effective approach to measure crystallization temperature of soft magnetic underlayer (SUL) for next generation of heat assisted perpendicular recording media. This approach uses temperature dependent reflectivity, which shows a clear jump when samples are crystallized. To achieve this measurement, an optical system is set up using hot plate and infrared laser. Reflectivity of SUL $(Co_{70}Fe_{30})_{92}Ta_3Zr_5$ shows a clear jump at its amorphous-crystalline transition temperature. Experiment results show this effect is clear in infrared region, and is weak for visible light.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2000.01a
• /
• pp.43-44
• /
• 2000

The fringe-field switching (FFS) display is known to exhibit wide-viewing-angle and high transmittance. We have simulated pretilt effects on electro-optic characteristic of the device when a liquid crystal with positive and negative dielectric anisotropy is used. The results show that asymmetry in contour of luminance and light leakage in the dark state are increased but voltage-dependent transmittance curves remain about the same, as the pretilt angle increases to $10^{\circ}$.

• Electrical & Electronic Materials
• /
• v.10 no.10
• /
• pp.989-994
• /
• 1997

In a Guest-Host cell the orientational ordering of dyes doped into liquid crystals has been investigated. To evaluate the influence of the host liquid crystals on the ordering of the dyes we have measured precisely the ordering parameters of the liquid crystals by using the dichroic ratio of the absorbances for infrared light polarized parallel and perpendicular to the diector. Our experimental results show that the ordering of the dyes can be expressed as a function of not only the molecular structure of the dyes but also the order parameter of the liquid crystals. These functions are dependent on the kinds of the liquid crystals and the dyes. Particularly the combination such as anthraquinone dyes doped into cyanobiphenyl liquid crystals show a very high ordering parameter. This is considered due to a strong intermolecular interaction between the dipoles of both liquid crystals and dyes.

• Macromolecular Research
• /
• v.10 no.3
• /
• pp.168-173
• /
• 2002

Unstabilized low-density polyethylene (LDPE) films and films formulated with hindered amine light stabilizer (HALS) were exposed to UV-radiation; and the physicochemical changes during photooxidation processes have been investigated using tensile, FTIR spectre-photometric and thermal analytical (DSC) techniques. The dependence of tensile properties (elongation- and stress-at-break), carboxyl index and heat of fusion on UV-irradiation time have been discussed. The use of HALS is found to be effective in maintaining the UV-mechanical properties of the LDPE films. The experimental results showed that there exists no correlation between mechanical properties and carbonyl index, whereas crystallinity correlates well with carbonyl index in unstabilized and stabilized films for irradiation times greater than 100 h. The rate of formation of carbonyl groups is found to be dependent on UV exposure time. Crystallinity of the film samples is strongly influenced by both exposure time and presence of HALS.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.1
• /
• pp.41-46
• /
• 2010

In this work, we report on the characterization of six low-$T_g$ poly[methyl-3-(9-carbazolyl) propylsiloxane] based photorefractive (PR) composites sensitized with poly(3-hexylthiophene) (P3HT) in different concentrations, ranging from 0.2 to 1 wt %. At 632.8 nm, photoconductivity, space charge field, refractive index modulation, and grating buildup time were measured versus external electric field. The photoconductivity was strongly dependent on the visible light absorption and mobility. The magnitude of space charge field was affected by the conductivity contrast $\sigma_{ph}/(\sigma_{ph}+\sigma_d)$. The refractive index modulation increased with the magnitude of space charge field and the PR grating buildup speed increased with the photoconductivity.