Recently, the ubiquitous environment in which anybody can reach a lot of information data without any limitations on the place and time has become an important social issue. There are two basic requirements in the field of information storage devices which have to be satisfied; the first is the demand for the improvement of memory capacity to manage the increased data capacity in personal and official purposes. The second is the demand for new development of information storage devices small enough to be applied to mobile multimedia digital electronics, including digital camera, PDA and mobile phones. To summarize, for the sake of mobile applications, it is necessary to develop information storage devices which have simultaneously a large capacity and a small size. Korea possesses the necessary infrastructure for developing such small sized information storage devices. It has a good digital market, major digital companies, and various research institutes. Nowadays, many companies and research institutes including university cooperate together in the research on small sized information storage devices. Thus, it is expected that small form factor optical disk drives will be commercialized in the very near future in Korea.

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Magnetic hard disk drive (HDD) technology is believed to be one of the most successful examples of modern mechatronics systems. The mechanical beauty of magnetic HDD includes simple but super high accuracy positioning head, positioning technology, high speed and stability spindle motor technology, and head-disk interface technology which keeps the millimeter sized slider flying over a disk surface at nanometer level slider-disk spacing. This paper addresses the challenges and possible approaches on how to further reduce the slider disk spacing whilst retaining the stability and robustness level of head-disk systems for future advanced magnetic disk drives.

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Thin, flexible, continuous structures known as webs are used in a wide range of industrial applications. These structures interact with the surrounding air in beneficial or detrimental ways, depending on the application and the process parameters. A review of the literature related to modeling and experimental work on (mostly) the steady state fluid-structure interactions is given. Equilibrium equations of web mechanics, and the inertia dominated and viscosity dominated air flows are presented. Simulation examples from four different industrial applications; web/air-bar interactions; roller/web interactions for permeable and impermeable webs; and the flat-top recording-head/magnetic-tape interactions, are presented.

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This paper presents the recent status of industry-university cooperative research activities in Japan on the mechatronics of information storage and input/output equipment. There are three research committees for promoting information exchange on technical problems and research topics of head-disk interface in hard disk drives (HDD), flexible media transport and image printing processes which are supported by the Japan Society of Mechanical Engineering (JSME), the Japanese Society of Tribologists (JAST) and the Japan Society of Precision Engineering (JSPE). For hard disk drive technology, the Storage Research Consortium (SRC) is supporting more than 40 research groups in various different universities to perform basic research for future HDD technology. The past and present statuses of these activities are introduced, particularly focusing on HDD and flexible media transport mechanisms.

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A stabilizing control technique for an inverted-double pendulum system consisting of two elastic links connected in series is developed, using a reduced-order model considering only the first vibration mode of the upper elastic beam, and applying an H^∞ controller design method for a mixed sensitivity problem that can consider multiplicative perturbations at the input port and is characterized by a settling function. It is found that although the coupling effect of different natural frequencies between the two flexible beams makes the stabilization problem more difficult, it is possible to stabilize the system by a feedback control using only the system’s output signals that include the vibration signal of the upper elastic beam. Furthermore, it is concluded that the more different the lowest natural frequencies of the two elastic beams are, the more easily the system can be stabilized.

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In this study, analysis and design of the hydraulic servo cylinder by using dual conical-cylindrical bearing with practical dimension is considered, which can be expressed by dimensionless forms for bearing performance parameters. The film viscosity is formulated as an exponential function of temperature and pressure. The thermohydrodynamic boundary condition is the basic assumptions of this analysis. Also, effect of the eccentricity ratio, misalignment factor and film thickness are considered in herein.

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Under recent low flying height conditions of magnetic head sliders, both the heat generated by the high-frequency current in the write coils and the rise in the ambient temperature cause local protrusion on head elements. Such protrusion reduces the flying height below the design value, thus reducing the safety margin for head/disk interference. To analyze this problem, we numerically simulated the heat transfer in the head slider, the thermal deformation of the head, and the flying height changes of the slider due to the deformation. The typical temperature distribution obtained from the simulation agrees well with reported experimental results. The simulation results show that decreasing the alumina base coat thickness can reduce the magnitude of a protrusion. For write-current-induced protrusions, the reduced flying height is partly compensated by increased air pressure on the air-bearing surface. However, almost the entire magnitude of an ambient-temperature-induced protrusion translates into flying height reduction.

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This paper proposes an optimal design scheme to reduce the noise of the engine cooling fan by adapting Kriging with two meta-heuristic techniques. An engineering model has been developed for the prediction of the noise spectrum of the engine cooling fan. The noise of the fan is expressed as the discrete frequency noise peaks at the BPF and its harmonics and line spectrum at the broad band by noise generation mechanisms. The object of this paper is to find the optimal design for noise reduction of the engine cooling fan. We firstly show a comparison of the measured and calculated noise spectra of the fan for the validation of the noise prediction program. Then, L₁₈ orthogonal array is applied as design of experiments because it is suitable for Kriging. With these simulated data, we can estimate a correlation parameter of Kriging by solving the nonlinear problem with genetic algorithm and find an optimal level for the noise reduction of the cooling fan by optimizing Kriging estimates with simulated annealing. We notice that this optimal design scheme gives noticeable results. Therefore, an optimal design for the cooling fan is proposed by reducing the noise of its system.

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This paper deals with the comparison of water-soluble cutting fluids for hobbing with dry cutting in performance, in terms of flank wear, crater wear and finished surface roughness, using TiN and (Al, Ti)N coated high-speed steel cutting tools. The experiments were performed using a fly tool of the same geometry as that of one tooth of a hob on the milling machine. The results helped clarify the following points: (1) The flank wear and the crater wear obtained with the water-soluble cutting fluids are larger than those obtained with the dry cutting, when using both TiN and (Al, Ti)N coated tools at the cutting speed of 117m/min, but in the case of the (Al, Ti)N coated tool at the high cutting speed of 159m/min, they are small when using the fluids. (2) The finished surface roughness when using the fluids is almost larger than that obtained in dry cutting, irrespective of the change in the kinds of coating films and the cutting speeds. (3) At the high cutting speed of 159m/min, the fluid containing the synthetic lubricating additive and the sulfuric EP additive is effective in the cutting performance compared with the dry cutting.

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Grinding fluids have been commonly used during the grinding of tools for their cooling and lubricating effect since the hard, robust materials used for cutting tools are difficult to grind. Grinding fluids help prevent a drop in hardness due to burning of the cutting edge and keep chipping to an absolute minimum. However, there is a heightened awareness of the need to improve the work environment and protect the global environment. Thus, the present study is aimed at applying dry grinding, cooling-air grinding, cooling-air grinding with minimum quantity lubrication (MQL), and oil-based fluid grinding to manufacturing actual endmills (HSS-Co). Cutting tests were performed by a vertical machining center. The results indicated that the lowest surface inclination values and longest tool life were obtained by cooling-air grinding with MQL. Thus, cooling-air grinding with MQL has been demonstrated to be at least as effective as oil-based fluid grinding.

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