Young Pil 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 70u2009nm and a patterning speed of 100u2009mm/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 19.5u2009nm, 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.

Vibration Analysis of HDD Actuator with Equivalent Finite Element Model of VCM Coil

As the rate of increase in areal density of the HDD has accelerated, dynamic characteristics of the HDD actuator need to be improved with respect to the performance of the tracking servo and shock transmission. Therefore, it is important to analyze the vibration characteristic of the HDD actuator that consists of the VCM part, E-block and pivot bearing. In this paper, vibration modes of the HDD actuator are investigated the using finite element and experimental modal analyses methods. To develop a detailed finite element model, finite element models of each components of the actuator assembly are constructed and tuned to the results of the EMA. The VCM coil is modeled as an equivalent finite element model that has an orthotropic material property using auto-model updating program. Auto-model updating program with improved sensitivity based iterative method is applied to build a detailed finite element model using the result of the EMA. A detailed finite element model of the HDD actuator is then constructed and analyzed.

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.

Acoustic noise and vibration analysis of solid state drive induced by multi-layer ceramic capacitors

Abstract Solid-state drives (SSDs), popular information storage devices, are typical printed circuit board assemblies (PCBA). As is true of other PCBAs, SSDs feature many multilayer ceramic capacitors (MLCCs). SSD vibration accompanied by high-pitched noise reflects the piezoelectric properties of MLCCs, and may cause great inconvenience to users. Here, we developed a finite element (FE) model predicting the vibration of the substrate associated with SSD acoustic noise. Because the SSD structure is complex and the model must be valid in the audible frequency range, we systematically constructed the model that is performed modal analysis. The excitation sources of the MLCCs were also modeled from a piezoelectric viewpoint, in which vibration analysis was performed in conjunction with the SSD model. Finally, the FE model was verified by comparing predicted and actual vibrations of an operational SSD.