No Cheol Park

Design of Tracked Vehicle with Passive Mechanism for Uneven Terrain

This paper describes design of tracked vehicle which can adapt rough terrain using passive link mechanism. The vehicle has two track modules at both sides which have four-bar link mechanism with passive spring elements. The passive spring elements of the link mechanism provide the restoring force which helps the vehicle to be changed to stable configuration when overcoming uneven terrains. The two track modules are connected with rotary joint so that it provides adaptability to laterally located terrain roughness. Simulating under various conditions, we verify our design concept and determine critical design parameter. We manufactured prototype vehicle with determined design parameters from simulation results. The vehicle has size of 295 mmtimes210 mmtimes105 mm, and weight of the vehicle is 1.31 kg. The prototype equips two 2.17 W DC motors as driving motors. We conducted experiments with manufactured prototype under various terrain conditions. The terrain conditions include steps, stairs, trench, and unstructured terrain. In experiments, this vehicle shows good overcoming ability for the tested terrain conditions

High-speed plasmonic nanolithography with a solid immersion lens-based plasmonic optical head

This letter describes the use of a plasmonic optical head to achieve high-speed nanopatterning. A plasmonic optical head employs both a sharp-ridged nanoaperture and a nanogap control to maintain the nanogap required for near-field nanolithography. The nanogap control uses a gap error signal produced by evanescent coupling through the air-gap. We demonstrate that a plasmonic optical head achieves a patterning resolution of 70 nm and a patterning speed of 100 mm/s. The proposed combination of a surface plasmon nanoaperture and a nanogap servo system is one of the strategies used to achieve high-speed, high-resolution nanolithography.

Applications of Next Generation Optical Data Storage Technologies

In recent years, there have been many research studies focusing on next generation optical data storage technologies, such as near-field recording and holographic data storage systems. Many studies from several disciplines have been perfoed and merged to realize of the next generation optical data storage. The technologies that have been developed for optical data storage are also essential for the other research areas. These technologies can be widely applied to various fields, such as near-field optics-based microscopy, small-sized imaging systems, plasmonic nanolithography using a solid immersion lens (SIL) and a nanoscale aperture, and bio-applications. In this paper, the applications and concepts of the next generation of optical storage technologies are discussed.

Mechanical Filter on Actuator for System Stability of 9.5 mm Drive

We propose a redesign method for modal parameters to depress the second resonance peak of an ultraslim optical pickup actuator. With the addition of the countermode near the second resonance frequency, we can achieve the gain margin, which is sufficient to meet the system requirement. It would alleviate the burden of the additional filter for a high-speed drive.

Application of Solid Immersion Lens-Based Near-Field Recording Technology to High-Speed Plasmonic Nanolithography

In this paper, we proposed a high-speed and high-throughput plasmonic nanolithography technique that uses a fabricated sharp-ridged nanoaperture on a solid immersion lens (SIL) and a precise active nanogap control algorithm. This plasmonic lithography with high throughput can make an optical spot with a diameter of the order of 10 nm and can perform nanopatterning at sub-m/s speed. An optical high-throughput head was designed on a metallic aluminum aperture by optimizing the geometric parameters of a sharp-ridged antenna on the basis of the optical intensity and spot size. Using the evanescent field generated from the SIL, the plasmonic SIL could be maintained below 20 nm above a photoresist-coated Si-wafer and could move at a speed of greater than 200 mm/s without friction; the patterning of lines could be performed under this condition. We achieved patterning with a line width (full-width at half-magnitude, FWHM) of 130 nm.

Experimental demonstration of line-width modulation in plasmonic lithography using a solid immersion lens-based active nano-gap control

Plasmonic lithography has been used in nanofabrication because of its utility beyond the diffraction limit. The resolution of plasmonic lithography depends on the nano-gap between the nanoaperture and the photoresist surface—changing the gap distance can modulate the line-width of the pattern. In this letter, we demonstrate solid-immersion lens based active non-contact plasmonic lithography, applying a range of gap conditions to modulate the line-width of the pattern. Using a solid-immersion lens-based near-field control system, the nano-gap between the exit surface of the nanoaperture and the media can be actively modulated and maintained to within a few nanometers. The line-widths of the recorded patterns using 15- and 5-nm gaps were 47 and 19.5 nm, respectively, which matched closely the calculated full-width at half-maximum. From these results, we conclude that changing the nano-gap within a solid-immersion lens-based plasmonic head results in varying line-width patterns.

Preisach modeling of dielectric elastomer EAP actuator

DE EAP(Dielectric Elastomer ElectroActive Polymer) has advantages in its weight, ease of fabrication and low power consumption. There are many efforts applied to various field in recent ten years. But the present modeling is not enough to appear its characteristics because of its hysteresis. In this paper, we propose modeling of DE EAP with Preisach Model that is used in order to model the hysteretic response arising in PZT and SMA. The modeling of DE EAP with Presach model is verified by experiment with various DE EAP actuators.

Analysis on the Characteristics of Stamped Base for 2.5 in HDD

In this study, we investigate the dynamic characteristics of a cold-rolled steel-plate (SPCC) stamped base for use with a 2.5-in hard disk drive (HDD). A stamped base offers the advantages of a thinner form and lower manufacturing cost compared to die-cast bases. The feasibility of applying a stamped base to a 2.5-in HDD is investigated by considering the various required characteristics. The manufacturing processes for stamped and die-cast bases are compared, revealing several advantages of stamped bases, including room-temperature processing, minimal contamination, fewer processing steps, and faster processing times. Finite element analysis is used to examine the dynamic and magnetic characteristics of the stamped base. The thin stamped base exhibits limited vertical stiffness, shock performance and magnetic force sensitivity. We observe only a slight difference in the temperature characteristics of stamped and die-cast bases. Additionally, internal air-flow analysis indicates an overall similar air velocity distribution in the stamped base compared to the die-cast base.

Analysis of slider dynamics induced by various ramp-disk contact situation in hard disk drive

This research investigates to analyze the effect of ramp-disk gap to slider dynamics in operational shock situation. To investigate the effect, simulations is conducted with verified finite element model include various ramp-disk gap. The slider dynamics is more unstable in bigger difference of ramp-disk gap model.

Quality-enhanced holographic system utilizing quantum-dot-based light source

We presented the digital holography (DH) system with enhanced image quality. While conventional DH uses highcoherence laser for illuminations, the speckle noise included in the image degrades the quality of the reconstructed data. To reduce the noise regards to the light source, lower-coherence light source could be applied in DH system. In this paper, the quantum dot (QD) based wavelength converter is utilized as the light source. Compared with light-emitting diode (LED), QD-based light source could be applied to versatile system, including dual-wavelength DH. Due to the low coherence both temporally and spatially, spatial filtering and collimation is presented. Also, numerical processes including noise reduction and aberration compensation is described to enhance the quality of the image. By experimental verifications, the proposed DH system shows better quality compared with conventional system, which is enough to utilize the quantitative measurement.