• Journal of Multimedia Information System
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• v.5 no.3
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• pp.215-220
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• 2018

This work presents a smart water quality sensor for hydroponic plant growing applications. The proposed sensor can effectively measure pH level and electrical conductivity of the water solution. The micro-controller incorporated in the sensor processes the raw sensor data, and converts it into a readable format. In addition, through the mobile interface realized using a WiFi module, the sensor can send data to the web server database that collects and stores the data. The data stored in the web server can be accessed by a personal computer or smart phone. The prototype sensor has been implemented, and the operations have been verified under an actual hydroponic plant growing application.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1279-1282
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• 2006

An ultra low-power down-conversion level shifter using low temperature poly-crystalline silicon thin film transistors is proposed for mobile applications. The simulation result shows that the power consumption of the proposed circuits is only 17% and the propagation delay is 48% of those of the conventional cross-coupled level shifter without additional area. And the measured power consumption is only 21% of that of the crosscoupled level shifter.

• Journal of the Korea Society of Computer and Information
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• v.23 no.3
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• pp.41-48
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• 2018

The recent sudden increase of big data has characteristics such as continuous generation of data, large amount, and unstructured format. The existing relational database technologies are inadequate to handle such big data due to the limited processing speed and the significant storage expansion cost. Current implemented solutions are mainly based on relational database that are no longer adapted to these data volume. NoSQL solutions allow us to consider new approaches for data warehousing, especially from the multidimensional data management point of view. In this paper, we develop and propose the integrated design methodology based on MongoDB for big data applications. The proposed methodology is more scalable than the existing methodology, so it is easy to handle big data.

• Journal of Computing Science and Engineering
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• v.10 no.2
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• pp.68-73
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• 2016

An efficient texture compression method is proposed based on a block matching process between the current block and the previously encoded blocks. Texture mapping is widely used to improve the quality of rendering results in real-time applications. For fast texture mapping, it is important to find an optimal trade-off between compression efficiency and computational complexity. Low-complexity methods (e.g., ETC1 and DXT1) have often been adopted in real-time rendering applications because conventional compression methods (e.g., JPEG) achieve a high compression ratio at the cost of high complexity. We propose a block matching-based compression method that can achieve a higher compression ratio than ETC1 and DXT1 while maintaining computational complexity lower than that of JPEG. Through a comparison between the proposed method and existing compression methods, we confirm our expectations on the performance of the proposed method.

• Journal of Computing Science and Engineering
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• v.3 no.3
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• pp.181-194
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• 2009

Flash memory is increasingly being used in a wide range of storage applications because of its low power consumption, low access latency, small form factor, and high shock resistance. However, the current platforms for flash memory software development do not meet the ever-increasing requirements of flash memory applications. This paper presents three different hardware platforms for flash memory/NVRAM (non-volatile RAM) software development that overcome the limitations of the current platforms. The three platforms target different types of host system and provide various features that facilitate the development and verification of flash memory/NVRAM software. In this paper, we also demonstrate the usefulness of the three platforms by implementing three different types of storage system (one for each platform) based on them.

• Journal of Korean Society for Quality Management
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• v.11 no.2
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• pp.10-17
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• 1983

The former paper (Part I) studies two methods for searching and determining the simple paths in an acyclic or a cyclic network. The two methods are computer programmed as subroutines (SPLP1 and SPLP2) for various use. And a few examples of its applications are discussed Another paper (Par II) studies the reliability computation for a network by using the Event Space Methods. A computer program is developed for the computation by applying the SPLP2 subroutine subprogram. In this paper the former results are summarized with another computer program for reliability computation by using the Path Tracing Methods. The two subroutines appear in the Appendix as reference for others. The programs can be used in the reliability computation of reducible and irreducible structure networks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.11
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• pp.5654-5673
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• 2016

Participatory sensing applications rely on recruiting appropriate participants to share their surrounding conditions with others, and have been widely used in many areas like environmental monitoring, health care, and traffic congestion monitoring, etc. In such applications, how to ensure the privacy of a participant is important, since incentive mechanisms are used to maintain their enthusiasm for sustainable participation by offering certain amount of reward. In this paper, we propose a pseudonym-based privacy protection scheme, that takes both privacy protection and user incentives into consideration. The proposed scheme uses the pseudonym mechanism and one-way hash function to achieve user incentives, while protecting their identity. We also show extensive analysis of the proposed scheme to demonstrate that it can meet the security and performance the requirement of a participatory sensing application.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3896-3915
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• 2014

The Reverse k Nearest Neighbor (RkNN) query is valuable for finding objects influenced by a specific object and is widely used in both scientific and commercial systems. However, the influence level of each object is unknown, information that is critical for some applications (e.g. target marketing). In this paper, we propose a new query type, Ordered Reverse k Nearest Neighbor (ORkNN), and make efforts to adapt it in an on-demand scenario. An Order-k Voronoi diagram based approach is used to answer ORkNN queries. In particular, for different values of k, we pre-construct only one Voronoi diagram. Algorithms on both the server and the clients are presented. We also present experimental results that suggest our proposed algorithms may have practical applications.

• Journal of the Korea Society of Computer and Information
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• v.21 no.2
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• pp.9-16
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• 2016

Recently, many research groups have focused on GPGPUs in order to improve the performance of computing systems. GPGPUs can execute general-purpose applications as well as graphics applications by using parallel GPU hardware resources. GPGPUs can process thousands of threads based on warp scheduling and CTA scheduling. In this paper, we utilize the traditional CTA scheduler to assign a various number of CTAs to SMs. According to our simulation results, increasing the number of CTAs assigned to the SM statically does not improve the performance. To solve the problem in traditional CTA scheduling schemes, we propose a new IPC-based dynamic CTA scheduling scheme. Compared to traditional CTA scheduling schemes, the proposed dynamic CTA scheduling scheme can increase the GPU performance by up to 13.1%.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1687-1689
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• 2000

In this study, a measuring system of the initial permeability of soft-ferrite powder was developed by using a differential transformer coil. and was investigated demagnetizing factors. Magnetic powder is extensively used for a magnetic fluid and microwave absorber materials etc. In these applications, it is very important for us to measure the initial permeability of magnetic ceramic powder. Unfortunately there are not any measuring equipment and method directly up to the present.