• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.6A
• /
• pp.524-532
• /
• 2002

This paper reports that the Lambert W function applies to a non-iterative design of minimum mean square-error scalar quantizers for a Laplacian source. Specifically, it considers a non-iterative design algorithm for optimum quantizers for a Laplacian source; it finds that the solution of the recursive nonlinear equation in the non-iterative design is elegantly expressed in term of the principal branch of the Lambert W function in a closed form; and it proves that the non-iterative algorithm applies only to exponential or Laplacian sources. The contribution of the paper is in the reduction of the time needed for the design and the increased accuracy in resulting quantization points and thresholds, because the algorithm is non-iterative and the Lambert W function can be evaluated as accurately as desired. Also, numerical results show how optimal quantization distortion converges monotonically to the Panter-Dite constant and help derive an approximation formula for the key parameters of optimum quantizers.

• Journal of the Korea Society of Computer and Information
• /
• v.26 no.9
• /
• pp.65-72
• /
• 2021

We consider the joint optimization problem of transmit power level, MMSE receiver filter and access point(AP) selection for multi access points environment. In the previous work, transmit power and MMSE receiver filter were jointly optimized[1] and transmit power and best access point were optimized jointly[2]. For each case, the algorithm was proposed and its convergence which guarantees the minimum total transmit power was proved. In this paper, we further improve the algorithm by jointly optimizing three parameters. More specifically, 1) we propose the algorithm by considering transmit power, MMSE receiver filter and access point selection jointly. 2) we prove that the proposed algorithm guarantees convergence with minimum transmit power consumption. In the simulation results, it is shown that proposed algorithm outperforms two other algorithms, i.e., 1) algorithm with transmit power and MMSE receiver filter, and 2) algorithm with transmit power and best access point selection.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.3
• /
• pp.51-61
• /
• 2023

Travel demand estimation of E-Scooter is the start point of solving the regional demand-supply imbalance problem and plays pivotal role in a linked transportation system such as Mobility-as-a-Service (a.k.a. MaaS). Most focuses on developing trip generation model of shared E-Scooter but it is no study on selection of an appropriate zone scale when it comes to estimating travel demand of E-Scooter. This paper aimed for selecting an optimal TAZ scale for developing trip distribution model for shared E-Scooter. The TAZ scale candidates were selected in 250m, 500m, 750m, 1,000m square grid. The shared E-Scooter usage historical data were utilized for calculating trip distance and time, and then applying to developing gravity model. Mean Squared Error (MSE) is applied for the verification step to select the best suitable gravity model by TAZ scale. As a result, 250m of TAZ scale is the best for describing practical trip distribution of shared E-Scooter among the candidates.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.1
• /
• pp.153-160
• /
• 2020

The kinetic energy of the rain drops was predicted in a relation between the rain rate and rain quantity, derived directly from the rain drop size distribution (DSD), which had been measured by a disdrometer located in the eastern state of Alagoas-Brazil. The equation in the form of exponential form suppressed the effects of large drops at low rainfall intensity observed at the beginning and end of the rainfall. The kinetic energy of the raindrop was underestimated in almost rain intensity ranges and was considered acceptable by the performance indicators such as coefficient of determination, average absolute error, percent relative error, mean absolute error, root mean square error, Willmott's concordance index and confidence index.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.7
• /
• pp.907-912
• /
• 1993

In this Paper we have proposed a new method to implement the interpolation of the functions, using a neural network. The architecture of neural network is a three-layer perceptron and the training algorithm is a modified error back propagation algorithm adding neurons to hidden layer. The interpolated functions are sin(7 X), 3rd order polynomial 0.5$\times$3_2$\times$2+X+2.5 and rectangular pulse 0.99 U (X-0.2) -0.99 U(X-0.8) +0.01, where U(X) is the unit step. The root mean squred errors of the interpolated functions are 0.00258, 0.00164 and 0.00116 respectively.

• Journal of Industrial Technology
• /
• v.20 no.A
• /
• pp.159-167
• /
• 2000

In the study rainfall frequency analysis attemped the many specific property data record duration it is differance from occur to error-term and probability ditribution of concern manifest. error-term analysis of method are fact sample data using method in other hand it is not appear to be fault that sample data of number to be small random variates. Therefore, day-rainfall data: to randomicity consider of this study sample data to the Monte Carlo method by randomize after data recode duration of form was choice method which compared an assumed maternal distribution from splitting frequency analysis consequence. In the conclusion, frequency analysis of chuncheon region rainfall appeared samll RMSE to the Gamma II distribution. In the rainfall frequency analysis estimate RMSE using random variates great transform, RMSE is appear that return period increasing little by little RMSE incresed and data number incresing to RMSE decreseing.

• Proceedings of the KIEE Conference
• /
• 2007.10a
• /
• pp.505-506
• /
• 2007

일반적으로 저가 장비를 이용한 수신 신호 강도(RSSI)의 측정은 전파의 특성상 다소 부정확한 정보를 제공하고, 이는 최소평균제곱오차(MMSE)를 이용한 위치 추정 방법에 있어 큰 오차 요인으로 작용한다. 따라서 이 논문에서는 수신 신호 강도를 이용한 기존의 위치 추정 방법을 개선하기 위해 센서 네트워크상의 유효 노드선정 알고리즘을 제시한다. 그리고 개선된 방법을 이용하여 센서 네트워크 기반의 실내 위치 추정 시스템을 구현 한다. 끝으로, 개선된 방법의 성능 검증을 위한 실험 결과를 제시 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.8
• /
• pp.91-97
• /
• 2008

The conventional WF(water-filling)-MIMO systems assumes that the channel state information is perfectly known at receiver. However, since, generally, the perfect channel state information is not available at receiver, channel estimation error should be considered at the system. Therefore, in this paper 4he performance of the conventional WF-MIMO systems is numerically analyzed when channel estimation error is considered. The analysis results show that mean square error of channel estimation up to $10^{-4}$ is tolerable to get the same performance obtained when perfect channel information is available.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.6 no.2
• /
• pp.1-9
• /
• 1988

The main objective of the study is to execute the simultaneous adjustment of the secondary level net on the basis of the 1st order level net adjustment carried in 1987. Moreover, the basic raw field data obtained during last 21-years(’67~’87) is to be analyzed, corrected and edited in order to carry out a reasonable adjustment of the End order level net. As the result of the study, we obtained mean random error η＝1.99$^{mm}$ /√km, mean systematic error ξ＝2.09$^{mm}$ /√km, square root of the posterior reference variance $\sigma$$_{0}$ ＝9.12$^{mm}$ /√km and concluded that the accuracy obtained is good enough for the category of precision levelling.

• The Journal of the Acoustical Society of Korea
• /
• v.16 no.3
• /
• pp.38-44
• /
• 1997

In this study, wer derived LMF-Sato, LMSF-Sato complex blind equalization algorithms for complex data. And then, the convergence rates, the convergence characteristics at the steady state and the stability of the proposed LMF and LMSF blind equalization algorithms are compared with those of LMS-Sato blind equalization algorithm. In simulations with 16-QAM data, LMF-Sato and LMSF-Sato algorithms showed better performance comparing with LMS-Sato algorithm generally. When the initial estimation errors of the weights of the equalizer are large, LMF-Sato algorithm showed ill characteristic in stability. However, LMSF-Sato algorithm has good covergence characteristics and preserves robustness.