• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.1
• /
• pp.139-149
• /
• 2007

Asynchronous OFCDM(Orthogonal Frequency and Code Division Multiplexing) systems must have a cell search process necessarily unlike synch개nous systems. this process is hewn initial synchronization and a three-step cell search algorithm is performed for the initial synchronization in the following three steps: OFCDM symbol timing, i.e., Fast Fourier Transform(FFT) window timing is estimated employing guard interval (GI) correlation in the first step, then the frame timing and CSSC(Cell Specific Scrambling Code) group is detected by taking the correlation of the CPICH(Common Pilot Channel) based on the property yielded by shifting the CSSC phase in the frequency domain. Finally, the CSSC phase within the group is identified in the third step. This paper proposes a modification group code with two or three block of the conventional CPICH based cell search algorithm in the second step which offers MS(Mobile Station) complexity reductions. however, the effect of the reduction complexity leads to degradation of the performance therefore, look for combination to have the most minimum degradation. the proposed block type group code with suitable combinations is the nearly sane performance as conventional group code and has a complexity reduction that is to be compared and verified through the computer simulation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.12 no.1
• /
• pp.37-42
• /
• 2019

In this paper, we propose a syndrome decoding scheme that can correct two errors for single error correcting Hamming codes within a code length. The decoding scheme proposed in this paper has the advantage of significantly improving the error rate performance compared to the decoder complexity by correcting multiple errors without substantially increasing the decoding complexity. It is suitable for applications in which the energy use of encoder/decoder is extremely limited and the low error rate performance is required, such as IoT communications and molecular communications. In order to verify the improvement of the error rate performance of the Hamming code with the proposed decoding scheme, we performed simulation on Hamming codes with short code length in the AWGN and BPSK modulation environments. As a result, compared with the conventional decoding method, the proposed decoding scheme showed performance improvement of about 1.1 ~ 1.2[dB] regardless of the code length of the Hamming code.

• Journal of Digital Contents Society
• /
• v.10 no.4
• /
• pp.493-499
• /
• 2009

Three methods frequently used for Hangul display in computer systems are Standard Johab Code in which each of Hangul consonants and vowels is given a 5-bit code and each syllable created by combining them forms a 2-byte code, Standard Wansung Code in which each of all the syllables generally used for Hangul presentation forms a 2-byte code, and Unicode in which each syllable in most of the world's language systems is given a unique code so that it allows computers to consistently represent and manipulate them in a unified manner. An embedded system in general has a lower processing power and a limited amount of storage space, compared to a personal compute(PC) system. According to its usage, however, the former may have a processing power equal to that of the latter. Hence, when Hangul display needs to be adopted, an embedded system must choose a display method suitable for its own resource environment. This paper introduces a TFT LCD initialization method and pixel display functions of an LN2440SBC embedded board on which an LP35, a 3.5" TFT LCD kit, is attached. Using the initialization and pixel display functions, in addition, we compare three aforementioned Hangul display methods, in terms of their processing speeds and amounts of memory space required. According to experiments, Standard Johab Code requires less amount of memory space but more processing time than Standard Wansung Code, and Unicode requires the largest amount of memory space but the least processing time.

• Structural Engineering and Mechanics
• /
• v.58 no.3
• /
• pp.597-612
• /
• 2016

This paper presents an optimization process using Harmony Search Algorithm for minimum weight of steel space frames under earthquake effects according to Turkish Earthquake Code (2007) specifications. The optimum designs are carried out by selecting suitable sections from a specified list including W profiles taken from American Institute of Steel Construction (AISC). The stress constraints obeying AISC-Load and Resistance Factor Design (LRFD) specifications, lateral displacement constraints and geometric constraints are considered in the optimum designs. A computer program is coded in MATLAB for the purpose to incorporate with SAP2000 OAPI (Open Application Programming Interface) to perform structural analysis of the frames under earthquake loads. Three different steel space frames are carried out for four different seismic earthquake zones defined in Turkish Earthquake Code (2007). Results obtained from the examples show the applicability and robustness of the method.

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.707-710
• /
• 2005

In this paper, we propose a new communication network for on-chip communication. The network is based on a direct sequence code division multiple access (DS-CDMA) technique. The new communication network is suitable for a parallel processing system and also drastically reduces the I/O pin count. Our network architecture is mainly divided into a CDMA-based network interface (CNI), a communication channel, a synchronizer. The network includes a reverse communication channel for reducing latency. The network decouples computation task from communication task by the CNI. An extreme truncation is considered to simplify the communication link. For the scalability of the network, we use a PN-code reuse method and a hierarchical structure. The network elements have a modular architecture. The communication network is done using fully synthesizable Verilog HDL to enhance the portability between process technologies.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.04a
• /
• pp.202-207
• /
• 2009

In this study, Numerical simulations were performed to analyze the characteristics of fire driven smoke flow for different location of fire source in the deeply underground subway station with using FDS code. The fire driven smoke-flow which was simulated by using Parallel Computational Method for fast calculation and LES for turbulence model. In this research, the fire location to obstruct a suitable egress from the fire disaster were discussed.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.1109-1112
• /
• 1998

In this paper, we propose a new architecture of the PN code acquistion system which has some shared blocks in order to reduce the hardware complexity. The proposed system has an energy calculation block which is shared by two active correlators. Our system is designed suitable for IS-95 based CDMA PCS. The new architecture was designed and simulated using VHDL. Also, We implemented it with Altera FPGA, and verified our system. The gate count is about 7,500. Our proposed architecture is also useful for multi-carrier system which uses the multiple searcher.

• Journal of computational fluids engineering
• /
• v.13 no.1
• /
• pp.7-13
• /
• 2008

Several high resolution schemes such as OSHER, MUSCL, SMART, GAMMA, WACEB and CUBISTA are comparatively studied with respect to the accurate capturing of fluid interfaces throughout the application to two typical test cases of a translation test and a collapsing water column problem with a return wave. It is accomplished by implementing the high resolution schemes in the in-house CFD code(PowerCFD) for computing 3-D flow with an unstructured cell-centered method and an interface capturing method, which is based on the finite-volume technique and fully conservative. The calculated results show that SMART scheme gives the best performance with respect to accuracy and robustness.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05a
• /
• pp.542-547
• /
• 1997

In the SSC(Super System Code), the reactivity feedback models of the Doppler effect and fuel axial expansion were modified to evaluate the safety performance of the metal-fueled core. The core radial expansion model was developed and implemented into the code as well. The transient analyses have been performed by the modified SSC for UTOP, ULOHS, ULOF/LOHS, and UTOP/LOF/LOHS events for one of the core design options being considered. Analysis results shows that the reactivity feedbacks can provide an inherent shutdown capability in response to key anticipated events without scram. Development of other reactivity feedback models and validation of these models against experimental data would make the SSC suitable for the assessment of the metal-fueled core safety performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2003.10a
• /
• pp.57-60
• /
• 2003

An axisymmetric compressible flow solver accounting for chemical equilibrium has been developed as an analysis tool exclusively suitable for performance prediction and optimum contour design of LRE thrust chamber. By virtue of several features focusing on user-friendliness and effectiveness including automatical grid generation and iterative calculations with changes in design parameters prescribed through only one keyword-type input file, a design engineer can evaluate very fast and easily the influences of various design inputs such as geometrical parameters and operating conditions on propulsive performance. Validations have been carried out for various aspects by detailed comparisons with the result of CEA code, experimental data of JPL nozzle, actual data for two historical engines, and ReTF data for KSR-III.