• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.201-202
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• 2004

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.182-183
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• 2004

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.187-189
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• 2007

In this paper, we present a model-driven approach for RTOS-based embedded software development and an automated tool that produces RTOS-specific code or RTOS-independent code. We define generic RTOS APIs (Application Programming Interface) that are not bound to any specific RTOS but provide most of typical RTOS services. Generic RTOS APIs can be used to describe application's RTOS-related behavior, The proposed API translator translates task code between C-code for specific RTOS and intermediate code using generic API. Also, the result can be extended to other RTOS's modifying XML transformation rule.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.40-43
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• 2015

A hybrid mesh based finite volume compressible flow code (PolySim) has been developed recently. Instead of the simple average method for the gradients of variables at each face, the volume average is applied for the calculation of the viscous flux. What is more, an improved Green Gauss method for the calculation of the gradient is also presented. These two techniques will improve both the accuracy and robustness of the code. The aerodynamic performance of this in-house cell centered code is examined by several widely-used bench-mark test cases. These cases include flows over flat plate and RAE 2822 etc. The comparisons on results between calculation and experiment are conducted. They show that the code can produce good numerical results which agree well with the corresponding experiment data.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.524-531
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• 1992

S/W의 구성은 기능을 실제로 수행하는 계산처리부와 사용자와 정보를 주고받는 User Interface부로 크게 나누어 볼 수 있다. 대부분의 S/W는 그 기능의 충실도와 아울러 편리한 사용법이 잘 어울려야 제역할을 할 수 있다. 따라서 편리한 User Interface를 만드는 일은 훌륭한 기능을 제공하는 것과 마찬가지로 S/W 개발자들이 지향해야 할 목표중 하나라 하겠다. 그러나 편리한 User Interface를 만드는 일은 전체 시스템개발 기간중 상당한 부분을 차지한다. 특히 CAD/CAM관련 S/W와 같이 사용자와 정보를 Graphic으로 주고받는 경우에는 User Interface의 구성이 더욱 더 어려워지며, 개발기간중 User Interace가 차지하는 비중은 더욱 커지게 된다. GUI는 최근들어 상당히 각광을 받고 있는 분야이며, 상당수의 GUI가 개발되어 있고, 이중 Unix용의 X-Window MS-DOS용의 MS-WINDOWS 3.0이 널리 사용되고 있다. 그러나 이러한 Window System들은 매우 다양한 기능을 제공하고 있음에도 불구하고, GUI자체의 덩치가 매우크고, S/W개발자가 익혀야하는 내용이 너무 복잡하여, 중/소형의 S/W개발에 사용하기에는 적합하지 않다. 본 연구에서는 GUI(Graphic User Interface)부분을 계산처리부와 완전분리하여, 범용성있는 개발용 Tool Kit을 구성함으로써 S/W개발자는 계산처리부만을 만들면되는 방안을 제시하고 있다. GS-GUI는 Menu처리부, Mouse/Keyboard입력처리부, Text/Graphic출력처리부로 나뉘어진다. Menu처리부는 Menu File로 주어지는 Menu Tree를 Pop-Up형태로 보여주며 User가 Menu를 선택할 수 있도록하며 선택된 Menu Item에 대한 Action Code를 계산처리부로 넘겨준다. 입력처리부에서는 Mouse와 Keyboard 어느것으로나 입력이 가능하도록 해준다. 출력처리부에서는 Action Code에 따라 계산처리부에서 계산된 결과를 화면에 보여주기 위한 각종 2D/3D Graphic Routine들이 포함되어있어 계산처리부에서 불러쓰도록 되어있다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.372.2-372
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• 2002

This paper presents an efficient modeling method fur open cracked beam structures. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of open cracks. The proposed method adopts the exact dynamic element method (EDEM) to avoid the difficulty and numerical errors in association with re-meshing the structure. The proposed method is rigorously compared with a commercial finite element code. (omitted)

• Journal of Communications and Networks
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• v.2 no.1
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• pp.58-68
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• 2000

In this paper we introduce the correlation-aided distributed sample acquisition (CDSA) scheme for fast cell search in IMT-2000 W-CDMA cellular system. The proposed scheme incorporates the state symbol correlation process into the comparison-correction based synchronization process of the original DSA scheme to enable fast acquisition even under very poor channel environment. for its realization, each mobile station (MS) has to store in its memory a set of state sample sequences. which are determined by the long-period scrambling sequences used in the system and the sampling interval of the state samples. CDSA based cell search is carried out in two stages : First, the MS first acquires the slot timing by using the primary synch code (PSC) and then identifies the igniter code which conveys the state samples of the current cell . Secondly. the MS identifies the scrambling code and frame timing by taking the comparison-correction based synchronization approach and, if the identification is not done satisfactorily within preset time. it initiates the state symbol correlation process which correlates the received symbol sequence with the pre-stored state sample sequences for a successful identification. As the state symbol SNR is relatively high. the state symbol correlation process enables reliable synchronization even in very low chip-SNR environment. Simulation results show that the proposed CDSA scheme outperforms the 3GPP 3-step approach, requiring the signal power of about 7 dB less for achieving the same acquisition time performance in low-SNR environments. Furthermore, it turns out very robust in the typical synchronization environment where large frequency offset exists.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.4 s.310
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• pp.73-79
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• 2006

Due to the powerful correcting performance, turbo codes have been adopted in many communication standards such as W-CDMA(Wideband Code Division Multiple Access), CDMA2000, etc., and implemented by hardware in many kind of fields. Although several hardware structures and improved algorithm have been proposed, these problems such as hardware area, operating speed and power consumption are still a major issue to be solved in practical implementations. In this paper, we designed the turbo-code decoder using MAX -SCALE operation derived from the posterior probability optimization. The proposed circuit has been measured their performance on Matlab and MaxPlusII and implemented on the FPGA As a result, when implementing the proposed algorithm on the FPGA, this circuit only occupies 616 logic elements. And comparing the performance with the MAP(Maxirnum a Posteriori) decoding algorithm, the operating speed was increased by about 40%(56.48MHz) and BER(Bit Error Rate) was increased by 6.12.

• Journal of the Korea Society of Computer and Information
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• v.6 no.3
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• pp.78-83
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• 2001

In this paper, we are considered Nakagami-m fading, which can model variable multipath mobile radio communication channel, in DS-CDMA system. System modeling using nakagami -m fading is suited for urban mobile communication channel with multipath. We used adaptive serial search PN code acquisition scheme and derived the detection probability($P_D$) and false alarm probability($P_FA$) which have influence on code acquisition time, over Nakagami-m fading. Detection probability($P_D$) and false alarm probability($P_FA$) are detection variable to decide PN code acquisition time and should use to calculate mean and variance. of acquisition time. From computer simulation, we analyzed mean and variance about PN code acquisition of fading channel. Then we can apply it to the H/W design of mobile communication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1A
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• pp.18-30
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• 2004

In this paper, the calibration problem of an asynchronous CDMA-based antenna array is studied. A new iterative calibration algorithm for antenna array in the presence of frequency offset error is presented. The algorithm is applicable to a non-linear array and does not require a prior knowledge of the (direction of arrivals) DOAs of the signals of any user, and it only requires the code sequence of a reference user. The algorithm is based on the two step procedures, one for estimating both channel and frequency offset and the other for estimating the unknown array gain and phase. Consequently, estimates of the DOAs, the multi-path impulse response of the reference signal sources, and the carrier frequency offset as well as the calibration of antenna array are provided. The performance of the proposed algorithm is investigated by means of computer simulations and is verified by using field data measured through a custom-built W-CDMA test-bed.