• Transactions of the Society of Information Storage Systems
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• v.6 no.1
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• pp.12-17
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• 2010

Thermally-assisted magnetic recording (TAMR) is a potentially promising approach to increase the storage density of hard disk drive (HDD). However, TAMR has some issues such as temperature effects, media problems, thermal deformation and light delivery. In this research, we focused on light delivery. One of the powerful methods to deliver the light from laser diode to recording medium is the use of an optical fiber and a specially designed prism. However, the TAMR with optical fiber may have some flyability problems induced by the mounted optical fiber and prism. Also, the TAMR suspension using an optical fiber has high vertical and pitch stiffness. Therefore, p-torque is greatly increased by the optical fiber. Also, flying height (FH) of the slider with TAMR suspension can be largely changed by p-torque. Therefore, in this paper, we focus on the pitch static attitude (PSA) tolerance and the FH by PSA of the TAMR suspension. The FH is investigated using various errors and the PSA tolerance for TAMR suspension is proposed.

• Korean Journal of Optics and Photonics
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• v.20 no.4
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• pp.236-240
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• 2009

LED modules, based on MCPCB with a hard barrier oxide layer and an improved thermal dissipation property, are presented. Reflecting cups were also formed on the surface of the MCPCB such that optical coupling between neighboring chips was minimized for improving the photon absorption loss. LED chips were directly attached on the MCPCB by using the COB (Chip On Board) scheme. The LED modules showed significantly enhanced light outputs, compared to the LED modules based on conventional MCPCBs.

• Korean Journal of Optics and Photonics
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• v.26 no.6
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• pp.312-317
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• 2015

We investigate the effect of laser-resonator mode size on the output of a Yb:YAG laser that is mode-locked by a semiconductor saturable absorber mirror (SESAM). We demonstrate that the smaller the product of the mode sizes at a SESAM and at a Yb:YAG crystal, the more stable the mode-locked output is. Also, we found numerically that there is a resonator length at which the mode-locked output occurs, regardless of the thermal lens effect of a Yb:YAG.

• Journal of the Korean Applied Science and Technology
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• v.18 no.4
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• pp.292-297
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• 2001

Zinc complexes with Bis[2-(o-hydroxyphenyl) benzothiazolato ligands (ZnPBS-0) and Bis[2- (o-hydroxynaphthyl) benzothiazolato ligands (ZnPBS-05) were synthesized, and luminescent properties of these materials were investigated. The emission band found that it strongly depends on the molecular structure of introduced ligand and was tuned from 525 nm to 535 nm by changing the ligand structures. Spreading of the ${\pi}-conjugation$ in 2-(o-hydroxyphenyl) group gives rise to a blue shift. On the other hand, spreading of the ${\pi}-conjugation$ in benzothiazole groups leads to a red shift. The EL properties also showed good consistency with their differences of ligand structure. Bright-blue EL emission with a maximum luminance of 8300 $cd/m^{2}$ at 11V was obtained from the organic light - emitting diodes (OLEDs) using ZnPBS-0 as emitting layer. It was also found that the newly synthesized materials were suitable to be used as emitting materials in organic EL device.

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.162-167
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• 2015

To investigate the effect of fluoro groups substitution on poly(p-phenylenevinylene) derivatives, poly(2,3,5,6- tetrafluoro-p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCTF-PPV, and poly[2,3,5,6-tetrafluoro-p-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], PMTF-PPV, were synthesized by the well-known Wittig condensation polymerization process. To compare the influences of fluoro groups, no fluoro groups containing model polymers, poly(p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCPPPV and poly[p-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], p-PMEH-PPV, were also synthesized. The resulting polymers were completely soluble in common organic solvents and exhibited good thermal stability up to 300℃. The polymers showed UV-visible absorbance and photoluminescence (PL) in the ranges of 259~452 nm and 500~580 nm, respectively. The tetrafluorophenyl containing PCTF-PPV and PMTF-PPV showed relatively red-shifted PL peaks at 521 nm and 580 nm, respectively, compared to that of non-fluoro groups containing polymers (PCP-PPV: 500 nm and p-PMEH-PPV: 539 nm). The single-layer light-emitting diode was fabricated in a configuration of ITO/polymer/Al. Electroluminescene (EL) emissions of PCP-PPV, PCTF-PPV, p-PMEH-PPV and PMTF-PPV were shown at 507, 524, 556, and 616 nm, respectively.

• Transactions of the Society of Information Storage Systems
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• v.10 no.2
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• pp.32-38
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• 2014

Heat emission from the laser diode used in the optical disc drive and the defects from the increased temperature at the system have attracted attentions from the field of the information storage device. Thermoelectric refrigerator is one of the fine solutions to solve these thermal problems. The refrigeration performance of thermoelectric device is dependent on the thermoelectric material's figure-of-merit. Meanwhile, high electrical contact resistivity between metal electrode and p- and n-type thermoelectric materials in the device would lead increased total electrical resistance resulting in the degeneracy in performance. This paper represents the manufacturing process of the PbTe-based material which has one of the highest figure-of-merit at medium-high-temperature, ~ 600K to 900 K, and the nickel contact layer for reduced electrical contact resistance at once, and the results showing the decent contact structure and figure-of-merit even after the long-term operation environment.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1735-1736
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• 2006

As developing the information society, Lighting Emitted diode(LED) which is light source for illumination of next generation is attracted public attention. LED have many problem as narrow light view angle, high price, drift phenomenon of color coordinate, high heating problem for lower power, lower weight and small size. So, many researches have continued in a illumination as LED module type. in this problem, heating problem is very important and difficult and that is caused in decreasing phenomenon of brightness and drift phenomenon of color coordinate. so the problem of heating is urgent question for illumination of LED. In this paper, structural design of PCB changed as two type for solving the heating problem. also the properties of heating is analysed and optical properties is measured with heating image camera and spectrometer according to change in this design.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.31-34
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• 2006

The characteristic of carbon nano fiber (CNF) as electron emitters was described. Carbon nano fiber (CNF) of herringbone was prepared by thermal chemical vapor deposition(CVD), mixed with binders and conductive materials, and then were formed by screen-printing process. In order to increase effectively field emissions, the surface treatment of rubbing & peel-off was applied to the printed CNF emitters on cathode electrode. The measurements of field emission properties were carried out by using a diode structure inline vacuum chamber. CNF of herringbone type showed good emission properties that a turn on field was as low as $2.5V/{\mu}m$ and current density was as large as $0.15mA/cm^2$ of $4.5V/{\mu}m$ with electric field. After the vacuum packaged panel of 5-inch in diagonal, the measured white brightness was as high as $7000cd/m^2$ at 1900V of anode and 700V of gate voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.448-448
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• 2007

OLED has many advantages of low voltage operation, self radiation, light weight, thin thickness, wide view angle and fast response time to overcome existing liquid crystal display (LCD)'s weakness. Therefore, It draws attention as promising display and has already developed for manufactured goods. Also, OLED is regarded as a only substitute of flexible display with a thin display. However, Indium tin oxide(ITO) thin film for electrode of OLED shows a low electrical properties and is impossible to deposit at high thermal condition because electrical characteristics of ITO is getting worse. One of the ways to realize an improved flexible OLED is to use high internal efficiency electrodes, which have higher work function than those single layer of ITO films of the same thickness. The high internal efficiency electrodes film is developed with structure of nickel oxide for bottom Emission Type of OLED.

• Transactions on Electrical and Electronic Materials
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• v.14 no.2
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• pp.59-62
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• 2013

At an infra-red (IR) wavelength of 1,064 nm, a diode-pumped Q-switched $Nd:YVO_4$ laser was used for the direct patterning of various transparent conductive oxide (TCO) thin films on glass substrate. With various laser beam conditions, the laser ablation results showed that the indium tin oxide (ITO) film was removed completely. In contrast, zinc oxide (ZnO) film was not etched for any laser beam conditions and indium gallium zinc oxide (IGZO) was only ablated with a low scanning speed. The difference in laser ablation is thought to be due to the crystal structures and the coefficient of thermal expansion (CTE) of ITO, IGZO, and ZnO. The width of the laser-patterned grooves was dependent on the film materials, the repetition rate, and the scanning speed of the laser beam.