• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.4
• /
• pp.54-60
• /
• 2006

A method for generating the compressor map from some performance measuring data using the hybrid intelligent technique was newly proposed. In order to improve accuracy of the traditional scaling method, a method to generate the compressor map using the GAs(Genetic Algorithms) was previously proposed, but the method has a drawback that it can not find correctly surge and choke points of the compressor map. However, the proposed hybrid intelligent method can determine obviously those points as well as improve the accuracy of the compressor map through complementarily using the GAs and the scaling method.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.6
• /
• pp.863-869
• /
• 2006

The behavior of submerged membrane bioreactor (SMBR) filtration systems utilizing rapid air backpulsing as a cleaning technique to remove reversible foulants was investigated using a genetic algorithm (GA). A customized genetic algorithm with suitable genetic operators was used to generate optimal time profiles. From experiments utilizing short and long periods of forward and reverse filtration, various experimental process parameters were determined. The GA indicated that the optimal values for the net flux fell between 263-270 LMH when the forward filtration time ($t_f$) was 30-37 s and the backward filtration time ($t_b$) was 0.19-0.27 s. The experimental data confirmed the optimal backpulse duration and frequency that maximized the net flux, which represented a four-fold improvement in 24-h backpulsing experiments compared with the absence of backpulsing. Consequently, the identification of a region of feasible parameters and nonlinear flux optimization were both successfully performed by the genetic algorithm, meaning the genetic algorithm-based optimization proved to be useful for solving SMBR flux optimization problems.

• Journal of Biomedical Engineering Research
• /
• v.39 no.5
• /
• pp.208-212
• /
• 2018

Microbial fuel cell (MFC) technology has been attractive since it can not only treat organic waste in an eco-friendly way by digesting it but also generate electricity by the unique metabolic process of microbes. However, it hasn't been employed in practical use until now because it is hard to integrate a small electricity up to an adequate amount of electric power and difficult to keep its bio-electric activity consistent. In this study, we combined an energy harvester with MFC (MFC-EH) to make the power-integration convenient and developed an energy self-sustainable wireless sensor system driven by a stable electric power produced by MFC-EH. Additionally, we build the low power application measuring data to be cast by the web in real-time so that it can be quickly and easily accessed through the internet. The proposed system could contribute to improvement of waste treatment and up-cycling technologies in near future.

• Journal of Computing Science and Engineering
• /
• v.11 no.4
• /
• pp.152-159
• /
• 2017

Three-dimensional (3D) printing is applied to many areas of life, but 3D printing models are stolen by pirates and distributed without any permission from the original providers. Moreover, some special models and anti-weapon models in 3D printing must be secured from the unauthorized user. Therefore, 3D printing models must be encrypted before being stored and transmitted to ensure access and to prevent illegal copying. This paper presents a selective encryption algorithm for 3D printing models based on clustering and the frequency domain of discrete cosine transform. All facets are extracted from 3D printing model, divided into groups by the clustering algorithm, and all vertices of facets in each group are transformed to the frequency domain of a discrete cosine transform. The proposed algorithm is based on encrypting the selected coefficients in the frequency domain of discrete cosine transform to generate the encrypted 3D printing model. Experimental results verified that the proposed algorithm is very effective for 3D printing models. The entire 3D printing model is altered after the encryption process. The decrypting error is approximated to be zero. The proposed algorithm provides a better method and more security than previous methods.

• Journal of Korea Multimedia Society
• /
• v.21 no.8
• /
• pp.897-908
• /
• 2018

In this paper, we propose a security framework for a cluster drones network using the MAVLink (Micro Air Vehicle Link) application protocol based on FANET (Flying Ad-hoc Network), which is composed of ad-hoc networks with multiple drones for IoT services such as remote sensing or disaster monitoring. Here, the drones belonging to the cluster construct a FANET network acting as WTRP (Wireless Token Ring Protocol) MAC protocol. Under this network environment, we propose an efficient algorithm applying the Lightweight Encryption Algorithm (LEA) to the CTR (Counter) operation mode of WPA2 (WiFi Protected Access 2) to encrypt the transmitted data through the MAVLink application. And we study how to apply LEA based on CBC (Cipher Block Chaining) operation mode used in WPA2 for message security tag generation. In addition, a modified Diffie-Hellman key exchange method is approached to generate a new key used for encryption and security tag generation. The proposed method and similar methods are compared and analyzed in terms of efficiency.

• Journal of Korea Multimedia Society
• /
• v.7 no.12
• /
• pp.1719-1728
• /
• 2004

The fusion of Internet technology and applications with wireless communication provides a new business model and promises to extend the possibilities of commerce to what is popularly called mobile commerce, or m-commerce. In mobile Internet banking service through wireless local area network, security is a most important factor to consider. We describe the development of security service for mobile Internet banking on Personal Digital Assistants (PDAs). Banking Server and Authentication Server were developed to simulate banking business and to support certificate management of authorized clients, respectively. To increase security, we took hybrid approach in implementation: symmetric block encryption and public-key encryption. Hash function and random number generation were exploited to generate a secret key. The data regarding banking service were encrypted with symmetric block encryption, RC4, and the random number sequence was done with public-key encryption. PDAs communicate through IEEE 802.IIb wireless LAN (Local Area Network) to access banking service. Several banking services and graphic user interfaces, which emulatedthe services of real bank, were developed to verity the working of each security service in PDA, the Banking Server, and the Authentication Server.

• Journal of Advanced Navigation Technology
• /
• v.13 no.1
• /
• pp.142-150
• /
• 2009

It is very important to generate a simplified model from a complex 3D character in computer game. We propose a new method of extracting feature lines from a 3D game character. Given an unstructured 3D character model containing texture information, we use model feature map (MFM), which is a 2D map that abstracts the variation of texture and curvature in the 3D character model. The MFM is created from both a texture map and a curvature map, which are produced separately by edge-detection to locate line features. The MFM can be edited interactively using standard image-processing tools. We demonstrate the technique on several data sets, including, but not limited to facial character.

• KIPS Transactions on Software and Data Engineering
• /
• v.5 no.4
• /
• pp.165-170
• /
• 2016

Using the intent of the Android application, an application can execute other application's components. However, if interaction between these components are not processed normally, such problems as incorrect component execution and unhandled system broadcast may be occurred. In this paper, to generate test scenarios for inter application interaction, a testing approach is proposed using a merged intent list and a single merged diagram. The proposed method can effectively be carried out to check the abnormal interaction among the applications which was not considered in existing testing approaches.

• Journal of Korean Society of Rural Planning
• /
• v.21 no.2
• /
• pp.115-126
• /
• 2015

Although the frequency of use for community facilities in rural villages is growing as well as the importance of the facilities for urban-rural exchange is being highlighted, study on spatial location-analysis of the facilities for such multi-purpose is not so much. This study aims to find the spatial distribution forms of community facilities in rural villages such as community center and rural-pocket park through location-analysis, in order to provide available data for selecting location in the future. As the study area, Sojeong-myeon, Sejong Special City was selected. This study conducted GIS analysis for criteria of the location-evaluation model developed in this study. This study introduced the concept of time-distance for accessibility analysis. This paper also used linear-consecutive scoring method(LCSM) as a scoring method of criteria and Analytic Hierarchy Process(AHP) method for weighting values of criteria. The application results showed that the new model can generate the intensity of community facilities according to spatial distribution and accessibility from cities to the facilities.

• Proceedings of the KSRS Conference
• /
• 2004.10a
• /
• pp.522-525
• /
• 2004

Interferometry SAR (InSAR) is a technique to generate topographic map from complex data pairs observed by antennas at different locations. However, to obtain topographic information using InSAR is difficult task because it requires series of complicated process including phase unwrapping and precise recovery of the SAR geometry. Especially, accuracy of the DEM (Digital Elevation Model) produced by repeat pass single SAR pair could be influenced by atmospheric effect. Recently, a new InSAR technique to improve accuracy of DEM has been introduced that utilizes low resolution DEM with a number of SAR image pairs. The coarse DEM plays an important role in reducing phase unwrapping error caused by layover and satellite orbit error. In this study, we implemented DInSAR (Differential InSAR) method which combines low resolution DEMs and ERS tandem pair images. GTOPO30 DEM with 1km resolution, SRTM-3 DEM with 100m resolution, and DEM with 10m resolution derived from 1:25,000 digital vector map were used to investigate feasibility of DInSAR. The accuracy of the DEMs generated both by InSAR and DInSAR was evaluated.