• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.9 no.3
• /
• pp.217-224
• /
• 2009

The traditional small educational multi-joint robots were developed on firmware. In these system's case, we cann't give a chance to educate good practices due on executing just robot's simple movements. But it may be possible for RTOS to control the elaborate movement of the robot with assembling each part on firmware. With this RTOS, we can enhance the efficiency of robot's movements, but too difficult to use the education as increasing the complexity of robot system. To solve the problem, we apply with Design pattern and Refactoring for the Education. Applying robot's design with Design pattern and Refactoring. There may be easily understand what and how to design RTOS for any level ones. We may easily change/upgrade RTOS for new system with this approach. This paper mentions to design RTOS with Design patterns and to apply RTOS's source code with Refactoring.

• Journal of Navigation and Port Research
• /
• v.36 no.5
• /
• pp.363-370
• /
• 2012

Recently, International Maritime Organization has been developing e-navigation implementation strategy plan, which is focused on various services for vessel safety navigation. Then, different kinds of software will be developed in maritime area and with this, the quality issues are to be expected becoming more important. In this paper, we adopt software refactoring techniques to reduce the complexity of structure on source code level. It makes software program more effective to understand and modify, without any change of outward behavior. The existing AIS broadcast server program is used as an example for our trial, and calculating coupling and cohesion metric are introduced to analyze the refactoring effect, taking account of the maintainability of IEC/ISO9126 software quality standards.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.3C
• /
• pp.209-214
• /
• 2003

Multi-mode coding method is a reliable DC-suppression method. There are two ways to improve the DC-suppression performance. One is improving scrambler's performance, and the other is improving selection criteria. The latter uses the MRDS(minimum running digital sum) criterion. It is easy to calculate, but its performance goes down when the length of codeword is getting longer. The MSW(mean squared weight) criterion that is known as the best so far regardless of the length of codeword has the high complexity. In this paper, we present the new selection criteria, MPRDS(minimum peak RDS) and A BSRDS(absolute RDS). Their performance are close to the MSW, implementation is simple. And also we present the SC(sign change) that has a subsidiary role with the original selection criteria and improve the capacity.

• The KIPS Transactions:PartD
• /
• v.15D no.4
• /
• pp.549-556
• /
• 2008

Web-based Enterprise Intranet System is developed Object-oriented programming language and data management is constructed using RDBMS. Between Object-oriented programming language and RDBMS bring about "Object-Relational Impedance Mismatch" due to heterogeneous paradigm. To solve this kinds of problems commonly use the ORM Framework that it is converting data between incompatible type systems in databases and object-oriented programming languages, uses complex mapping metadata. It causes difficult to develop and maintain because of inflexible in changes. This paper proposed persistence framework that solve the existing complexity of ORM framework and has more flexible in evolution of database table. This persistence framework is unnecessary meta information that connecting with entity of database table and the objects, it offers users convenience of maintenance and it allows far more flexible and affordable systems to be built because of automatically code generation. The result of testing based on the proposed persistence framework with Hibernate, iBATIS, It is similar response time with iBATIS and it has more about three times faster than Hibernate. But iBATIS has problems of mass data processing.

• Journal of IKEEE
• /
• v.16 no.2
• /
• pp.138-144
• /
• 2012

In this paper, a semi-analytical approach is proposed for DSF(Decode and Selective Forward)-Relay MC-CDMA(MultiCarrier-Code Division Multiple Access) systems over multipath Rayleigh fading channels. Considering BER(bit error rate) performance and complexity, the MMSE-C(Minimum Mean squared Error-per subCarrier) is used as the combining method for MC-CDMA systems. At first, the analytical method based on error-events at relay nodes for DSF-Relay schemes is utilized in order to derive the averaged BER. Then, the averaged BER is expressed as the form considering possible all error-events. Also, proposed semi-analytical expressions have been verified by comparing with simulation results. Finally, it is verified that the derived analytical expressions can be a frame work to cover different multipath Rayleigh fading channel conditions and to measure the upper performance for DSF-Relay MC-CDMA systems.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.37 no.7
• /
• pp.1-8
• /
• 2000

In this paper, we introduce a modified interference cancellation scheme for multiuser detection in CDMA(Code Division Multiple Access). This detector uses SIC(Successive Interference Canceller) scheme and divides the received signals to reduce the delay time. In this proposed structure, the active users are divided into a number of groups. Within each group, parallel detection is performed to estimate the output signal of that group. The estimated output signal due to that group is then subtracted from the received signal and the resulting residual signal is used for the parallel detection of the next group. This parallel and serial cancellation process is repeated until the last group in the stage is completed. The estimated output signals due to all groups except -th group are MAI for the user signals in -th group. Therefore, the estimated output signals due to all groups except th group are subtracted from the received signal, and then the obtained signal becomes the input signal of -th SIC. The proposed RDSIC (Reduced Delay time of Successive Interference Canceller) has performance and complexity close to the SIC, but with much less detection delay.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.4 s.95
• /
• pp.351-358
• /
• 2005

In this paper, STBC(Space Time Block Code) is applied to the UWB system and frequency repeated diversity is used to get the 4-th order space time diversity gain. The performance of UWB STBC-OFDM system is analyzed by computer simulation. As a result of analysis, proposed UWB system can reduce the complexity that is introduced by increaing number of radiator and show the same performance of 4 antennas with that only using 2 radiator. This system at the $10^{-4}$ also shows the enhancement of $7.1\;\cal{dB}$ to the general UWB OFDM and $1.9\;\cal{dB}$ to UWB STBC-OFDM.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.7
• /
• pp.1321-1327
• /
• 2009

In this paper, as the mobile communication service is widely used and the demand for wireless repeaters is rapidly increasing because of the easiness of extending service areas. But a wireless repeater has a problem the oscillation due to feedback signal. We proposed a new hybrid interference canceller using the adaptive filter with CMA(Constant Modulus Algorithm)-Grouped LMS(Least Mean Square) algorithm in the adaptive interference canceller. The proposed interference canceller has better channel adaptive performance and a lower MSE(Mean Square Error) than conventional structure because it uses the cancellation method of Grouped LMS algorithm. The proposed detector uses the LMS algorithms with two different step size to reduce mean square error and to obtain fast convergence. This structure reduces the number of iterations for the same MSE performance and hardware complexity compared to conventional nonlinear interference canceller.

• The KIPS Transactions:PartA
• /
• v.14A no.3 s.107
• /
• pp.151-158
• /
• 2007

Quadtree, which is a hierarchical data structure, is a very important data structure to represent images. The linear quadtree representation as a way to store a quadtree is efficient to save space compared with other representations. Therefore, it has been widely studied to develop efficient algorithms to execute operations related with quadtrees. The computation of block location is one of important geometry operations in image processing, which extracts a component completely including a given block. In this paper, we present a constant time algorithm to compute the block location of images represented by quadtrees, using three-dimensional $n\times n\times n$ processors on RMESH(Reconfigurable MESH). This algorithm has constant-time complexity by using efficient basic operations to deal with the locational codes of quardtree on the hierarchical structure of $n\times n\times n$ RMESH.

• The KIPS Transactions:PartA
• /
• v.10A no.3
• /
• pp.207-214
• /
• 2003

Quadtree, which is a hierarchical data structure, is a very important data structure to represent binary images. The linear quadtree representation as a way to store a quadtree is efficient to save space compared with other representations. Therefore, it has been widely studied to develop efficient algorithms to execute operations related with quadtrees. The linear translation is one of important operations in image processing, which moves the image by a given distance. In this paper, we present an algorithm to perform the linear translation of binary images represented by quadtrees, using three-dimensional $n{\times}n{\times}n$ processors on RMESH (Reconfigurable MESH). This algorithm has constant-time complexity by using efficient basic operations to route the locational codes of quardtree on the hierarchical structure of n${\times}$n${\times}$n RMESH.