• Journal of Communications and Networks
• /
• v.15 no.3
• /
• pp.276-282
• /
• 2013

Self-encoded spread spectrum (SESS) is a novel modulation technique that acquires its spreading code from a random information source, rather than using the traditional pseudo-random noise (PN) codes. In this paper, we present our study of the SESS system performance under pulsed-noise jamming and show that iterative detection can significantly improve the bit error rate (BER) performance. The jamming performance of the SESS with correlation detection is verified to be similar to that of the conventional direct sequence spread spectrum (DSSS) system. On the other hand, the time diversity detection of the SESS can completely mitigate the effect of jamming by exploiting the inherent temporal diversity of the SESS system. Furthermore, iterative detection with multiple iterations can not only eliminate the jamming completely but also achieve a gain of approximately 1 dB at $10^{-3}$ BER as compared with the binary phase shift keying (BPSK) system under additive white gaussian noise (AWGN) by effectively combining the correlation and time diversity detections.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.8 no.3
• /
• pp.361-374
• /
• 1996

In general, a cooling tower has two major noise sources, one is the fan and the other is the falling water. The fan noise is produced by passage of its blades through the air and radiates from the fan stack. Noises from the falling water are caused by splashing and dropping of water cascading over the internal filler of the cooling tower and into the basin and radiate from the louvered face. In this paper, the noise measurements and its frequency analysis are carried out for the locations facing the louvered side and near the fan stack referring the related code and standards in order to study the noise characteristics of the induced-draft cooling tower, especially for the buildings. As a result, it is found that for every doubling of distance from the noise source the noise level decreases by 2~4dBA in the near field with reflect surfaces and decreases by about 6dBA also in the far field without reflect surfaces. As a supplement to the noise measurements, a computer program with simple algorithm is developed in order to estimate the noise level at a distance from the cooling tower, so that the user could apply and modify it for the particular boundary conditions easily.

• ETRI Journal
• /
• v.27 no.6
• /
• pp.691-696
• /
• 2005

In asynchronous transfer mode (ATM) networks, fixed length cells of 53 bytes are transmitted. A cell may be discarded during transmission due to buffer overflow or a detection of errors. Cell discarding seriously degrades transmission quality. The quality degradation can be reduced by employing efficient forward error control (FEC) to recover discarded cells. In this paper, we present the design and implementation of decoding equipment for FEC in ATM networks based on a single parity check (SPC) product code using very-large-scale integration (VLSI) technology. FEC allows the destination to reconstruct missing data cells by using redundant parity cells that the source adds to each block of data cells. The functionality of the design has been tested using the Model Sim 5.7cXE Simulation Package. The design has been implemented for a $5{\times}5$ matrix of data cells in a Virtex-E XCV 3200E FG1156 device. The simulation and synthesis results show that the decoding function can be completed in 81 clock cycles with an optimum clock of 56.8 MHz. A test bench was written to study the performance of the decoder, and the results are presented.

• Electronics and Telecommunications Trends
• /
• v.32 no.6
• /
• pp.83-95
• /
• 2017

The trend of manycore hardware has recently evolved more quickly than expected. However, an operating system, which is software used for managing computer resources, is still optimized for a multicore system. To handle this issue, we started a research project called 'Research on High Performance and Scalable Manycore Operating Systems' in 2014. This article briefly examines the technology trends of manycore hardware and operating systems, and introduces the research areas and outcomes during the first stage of the project(2014-2017). The core technologies improving the performance scalability of manycore systems are publicly available, and anyone can use the source code or apply the ideas of the core technique to other research activities. In addition, the research plans of the second stage of the project(2018-2021) are also included.

• The KIPS Transactions:PartC
• /
• v.13C no.1 s.104
• /
• pp.75-82
• /
• 2006

In this paper, a space-frequency coded orthogonal frequency division multiplexing (SFC-OFDM) scheme with dual Viterbi decoder is proposed and analyzed. Here, two independent half-rate OFDM symbols are generated after convolutional coding of the binary source code. A dual Viterbi decoder is exploited to decode the demodulated sequences independently in the receiver, and their path metrics are compared. Accordingly, the recovered binary data in the proposed scheme are composed of the combination of the sequences having larger path metrics while those in a conventional system are simply the output of single Viterbi decoder. As a result, the proposed SFC-OFDM scheme has a better performance than the conventional one for all signal-to-noise power ratio.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.5
• /
• pp.815-825
• /
• 2015

DNP3(Distributed Network Protocol) is one of the most representative protocols which is used in SCADA(Supervisory Control and Data Acquisition) system. IEC 62351 is listing the integrity, confidentiality, availability and non-repudiation or accountability as the security requirement. However, IEEE Std. 1815 that is DNP3 standards does not define a mechanism for non-repudiation or accountability. In this paper, we propose a non-repudiation of origin technique about the sender of critical ASDU and implement the proposed scheme using software such as OpenSSL and SCADA source code library.

• The KIPS Transactions:PartD
• /
• v.16D no.6
• /
• pp.871-880
• /
• 2009

Along with the complexity and size growth of embedded software, it is critical to meet the nonfunctional requirements such as power consumption as well as functional requirements such as correctness. This paper, apart from the existing studies of source code-based power analysis, proposes an approach of model-based power analysis using UML 2.0. Specially, we focus on the development of energy library to analyze the power consumption of embedded software. Our energy library supports model-based power analysis, and also supports the easy adaption for the change of embedded application.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2016.04a
• /
• pp.529-532
• /
• 2016

IT 융 복합 산업에서 소프트웨어가 차지하는 비중이 높아짐에 따라 프로젝트 관리는 점차 중요해지고 IT기업의 경쟁력을 결정하는 중요 요소가 되고 있다. 프로젝트 관리 중 일정 관리는 가장 기초적이고 관리적 요소가 가장 많이 들어있으며 일정 관리의 실패는 Time-To-Market을 맞추지 못한다. 일정 관리를 위해 고려해야할 문제점들은 겉으로 확인되는 진척율과 실제로 개발된 진척율의 차이, 팀원의 낭비되는 시간을 지속적 관리 등이 있음에도 현장에서는 도구 또는 파일을 통해 진행 사항을 관리하지만 세부 작업별 활동까지 연계가 되지 않아 일정 관리의 진행 상황이 명확히 드러나지 않는다. 따라서 본 논문에서는 소스코드 기반의 실시간 프로젝트 일정 관리 도구를 제안한다. 프로젝트 계획 단계에서 작업을 컴포넌트 별로 세분화되어 있을 때 이 도구를 사용하여 컴포넌트 내부 메서드의 소스코드 작성을 통해 소프트웨어 개발 진척도를 명확하게 파악하고 해당 소스 코드의 테스트를 통해 의도대로 개발이 이루어졌는지를 확인 가능하다. 그리고 피드백을 통해 개발자에게 개발 일정 및 계획 수정에 대한 알림으로 지연되는 시간 없이 수정 가능하다.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.08a
• /
• pp.144-151
• /
• 2003

Computations of the mean and turbulence flows over three-dimensional hill of conical shape have implemented. Beside the standard $\kappa-\epsilon$, two other modifications proposed by Detering & Etling and Duynkerke for atmospheric applications were also considered. These predictions were compared with the data of a wind tunnel experiment. From the comparison, it was concluded that all three models predict the mean flow velocities equally well while only the Duynkerke's model accurately predicts the turbulence data statistics. It also concluded that there are large discrepancies between model predictions and the measurements near the ground surface. The flow field, which was obtained by using the Duynkerke's modification, was used to simulate gas dispersion from an upwind source. The calculation results are verified based on the measurement data. Modifications of the turbulent Schmidt number were carried out in order to match the measured results. The code was used to investigate the influence of the recirculation zone behind a building of cubical shape on the transport and dispersion of pollutant. For a stack behind and near the obstacle, some conclusions about the effect of the stack height and stack location were derive

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.2017-2022
• /
• 2004

There are multistage preheaters in the power generation plan to improve the thermal efficiency of the plant and to prevent the components from the thermal shock. The energy source of these heaters comes from the extracted two phase fluid of working system. These two-phase fluid can cause the so-called Flow Accelerated Corrosion(FAC) in the extracting piping and the bubble plate of the heater for example, in case of point Beach Nuclear Power Plant and in the Wolsung Nuclear Power Plant. The FAC is due to the mass transport of the thin oxide layer by the convection. FAC is dependent on many parameters such as the operation temperature, void fraction, the fluid velocity and pH of fluid and so on. Therefore, in this paper velocity was calculated by FLUENT code in order to find out the root cause of the wall thinning of the feedwater heaters. It also includeed in the fluid mixing analysis model are around the number 5A feedwater heater shell including the extraction pipeline. To identify the relation between the local velocities and wall thinning, the local velocities according to the analysis results were compared with distribution of the shell wall thicknes by ultrasonic test.