• Journal of Information Technology Applications and Management
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• v.11 no.2
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• pp.29-43
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• 2004

As the development of an information technique, gradually, mobile device is going to be miniaturized and operates at high speed. By such the requirements, the devices using a flash memory as a storage media are increasing. The flash memory consumes low power, is a small size, and has a fast access time like the main memory. But the flash memory must erase for recording and the erase cycle is limited. JFFS is a representative filesystem which reflects the characteristics of the flash memory. JFFS to be consisted of LSF structure, writes new data to the flash memory in sequential, which is not related to a file size. Mounting a filesystem or an error recovery is achieved through the sequential approach. Therefore, the mounting delay time is happened according to the file system size. This paper proposes a MJFFS to use a multi-checkpoint information to manage a mass flash file system efficiently. A MJFFS, which improves JFFS, divides a flash memory into the block for suitable to the block device, and stores file information of a checkpoint structure at fixed interval. Therefore mounting and error recovery processing reduce efficiently a number of filesystem access by collecting a smaller checkpoint information than capacity of actual files. A MJFFS will be suitable to a mobile device owing to accomplish fast mounting and error recovery using advantage of log foundation filesystem and overcoming defect of JFFS.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.764-771
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• 2006

Knowledge of ground thermal properties is most important for the proper design of large BHE(borehole heat exchanger) systems. Thermal response tests with mobile measurement devices were first introduced in Sweden and USA in 1995. Thermal response tests have so far been used primarily for in insitu determination of design data for BHE systems, but also for evaluation of grout material, heat exchanger types and ground water effects. The main purpose has been to determine insitu values of effective ground thermal conductivity, including the effect of ground-water flow and natural convection in the boreholes. Test rig is set up on a small trailer, and contains a circulation pump, a heater, temperature sensors and a data logger for recording the temperature data. A constant heat power is injected into the borehole through the pipe system of test rig and the resulting temperature change in the borehole is recorded. The recorded temperature data are analysed with a line-source model, which gives the effective insitu values of rock thermal conductivity and borehole thermal resistance.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.710-714
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• 2009

Optical discs' capacity has increased. In case of Blu-Disc, it can store data up to 25 GB. Due to the large capacity, it can substitute tape devices for the use of backup. However, optical discs' surfaces are exposed so that it can lose data easily by exterior damages like scratches. Therefore additional reliability must be provided to maintain data for a long time. In this paper, we suggest a writing technique that gives optical discs additional reliability. Redundant data, generated by LDPC codes, are stored in disc along with the original data. These original data and redundant data are scattered over the disc to avoid losing a large part of data with one scratch. By deploying data with the distance that provides the reliability a user wants, we can enhance optical discs' reliability.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.518-520
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• 2006

Due to the rapid popularization of mobile multimedia devices and the Internet as well as the realization of high-speed data transmission and large-volume data recording media, high quality content distribution and ubiquitous information services are making progress and a new type of information distribution and network sharing service has gradually emerged into the market. It is capable of utilizing terabyte sized home servers also in private homes. Under these circumstances, in distribution of content over shared networks, it is crucial to establish DRM (Digital Rights Management) technologies to protect the content from illegal copying and usage. A truly successful DRM system must be built on open worldwide specifications and provide maximum interoperability and user acceptance. An open interoperability of DRM is able to construct highly expandable PKI based DRM, targeting usage between systems, considering the expansion of recent content distribution services and clients This document gives protocol specifications for the exchange of rights information between the DRM module, description of specifications for rights information and encrypted content formats.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.628-633
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• 1996

Large saturation magnetization $4pM_s$ is essentially required for soft magnetic thin layers used in magnetic recording devices. Amorphous Co-based alloys and Fe-Co alloys may be regarded as one of the candidates for soft magnetic materials which possess large $4\piM_s$. Some preparation process to improve soft magnetism of these films were performed in this study. Addition of Ta seemed to be effective to change the magnetostriction constant $\lambda$ from positive value to negative one. The magnetoelastic energy $K_e$ is strongly dependent on $\lambda$. $(Co_{95.7}Zr_{4.3})_{100-x}Ta_x$ films with $K_e$ of negative value have sufficiently soft magnetic characteristics. $Fe_{90}Co_{10}$ alloy exhibits extremely large $4\piM_s$, of about 24 kG. Addition of N and Ta to $Fe_{90}Co_{10}$ films improved the soft magnetism of them. The $Fe_{82.0}Co_{7.6}Ta_{10.4}$:N/Ti multilayered films exhibit better soft magnetic properties and better thermal stability than Fe-Co-Ta:N singlelayer films.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.141-147
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• 1999

Optical disk technology with a laser beam for data recording and retrieval is one of the most promising route for high density information storage in multimedia era. As the storage density and data transfer rates are increased, mechanical issues, mainly noise and vibration, become critical. Rubber materials are extensively used in various machine design application, mainly for vibration/shock/noise control devices. Over the years an enormous effort has been put into developing procedures to provide properties of rubber components with complex shape and under pre-deformed state. In this paper, non-linear large deformations of a rubber mount for optical disk drive were investigated using the finite element method. A tension test of rubber material was performed, to calculate a strain energy function. According to the pre-deformed state, the variation of rubber mount stiffness were calculated and the reliability of numerical results were checked by compared with the measuring the deflection values. Also, the effects of the pre-deformed rubber mount on the system dynamic characteristics were investigated and the relation between the static stiffness variation of rubber mount and the natural frequence variation of system was discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.581-586
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• 2009

Knowledge of ground thermal properties is most important for the proper design of large scale BHE(borehole heat exchanger) systems. The type, pipe size and thermal performance of the BHE is highly dependent on the ground source heatpump system-efficiency and instruction cost. Thermal response tests with mobile measurement devices were developed primarily for insitu determination of design data for large diameter BHE for triple-U spacer apply. The main purpose has been to determine insitu values of effective ground thermal conductivity and thermal resistance, including the effect of ground-water flow and natural convection in the boreholes. The test rig is set up on a some trailer, and contains a circulation pump, a inline heater, temperature sensors, flow meter, power analysis meter and a data logger for recording the temperature, fluid flow data. A constant heat power is injected into the borehole through the tripl-U pipes system of test rig and the resulting temperature change in the borehole is recorded. The recorded temperature data are analysed with a line-source model, which gives the effective insitu values of rock thermal conductivity and borehole thermal resistance of large diameter BHE for spacer apply.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.48-53
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• 2014

Rocket, held using the CCA for the mission, a plurality of recording devices, and navigation equipment. In case of a projectile which is entered the water after fired into the air, after performing stages and fairing separated in flight to enter the underwater. It is caused by the explosion of gunpowder mainly, vibration phenomenon of a large transition is induced structurally very, also on entering the water, have a significant shock structurally separated. If shock is transmitted directly to the CCA through the body, it can be caused malfunction of payloads, resulting in failure of the mission of the projectile. In order to ensure the stability against shock, in this paper, Calculating a target resonacne frequency of the CCA, and verified through modal test and analysis. Maximum acceleration position of CCA is checked by SRS analysis. In addition, effectiveness of shock isolation system through shock analysis.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.124-127
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• 2005

Rewritable optical memory devices such as an CD-RW and DVD+RW are data storage media, which take advantage of the different optical properties in the amorphous and crystalline states of phase change materials. The switching property, structural transformation, transformation kinetics and chemical bindings of $Ge_xSb_{100-x}$($6{\le}x{\le}$34) were studied to investigate the feasibility of applying $Ge_xSb_{100-x}$ alloys in optical memory. The $Ge_xSb_{100-x}$ thin film was deposited by RF magnetron co-sputtering system and phase change characteristics were investigated by X-ray diffraction (XRD), static tester, inductively coupled plasma atomic emission spectrometer (ICP-AES) and atomic force microscopy (AEM). Optimum fiim composition of $Ge_xSb_{100-x}$ was studied and its minimum time fur laser induced crystallization and optical contrast fur phase transition was performed. These results might be correlated with the binding energies between Ge and Sb, and indicate that $Ge_xSb_{100-x}$ have an potential far optical memory applications.

• Journal of the Korea Society of Computer and Information
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• v.23 no.4
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• pp.71-80
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• 2018

In this paper, we developed an interactive animation authoring tool and developed the Android based interactive edutainment contents. The authoring tool for creating interactive animations developed in this paper is based on a graphical user interface, so users can easily create interactive animations. Interactive animation contents created by this authoring tool can be created as images and xml files so that they can be used directly on mobile devices. In order to increase learning efficiency for children, Android-based interactive edutainment electronic storybooks, which is implemented using this authoring tool, provided a recording function to listen to the parents' voice as well as an interactive action in which the characters move in accordance with the story line. We also provided a STEAM game that combines creativity and imagination with creative science and technology. Therefore, by creating the edutainment contents through the proposed authoring tool for interactive animation, various interactive animation contents could be produced more easily than the code implementation method. Through this study, I hope that it will be helpful for the development of various interactive edutainment contents to provide educational contents considering the quantity and quality to infants.