• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.5
• /
• pp.499-504
• /
• 2011

In this paper, we suggest a method for discretized frequency modulations of ultrasonic signals. A continuous sweep of frequency modulation signals can be modelled with fine levels of discretization. If the ultrasound signals are modulated with monotonically decreasing frequencies, then the cross-correlation between an emitted signal and received signal can be used to identify the distance of multiple target objects. For the discretized frequency synthesis, CF ultrasounds with different frequencies are serially ordered. The auto-correlation test with the signal shows effective results for distance estimation. The discretized frequency syntheses have better distance resolution than CF ultrasound signals and the resolution depends on the number of the combined ultrasound frequencies.

• Journal of Korean Society for Quality Management
• /
• v.21 no.1
• /
• pp.181-189
• /
• 1993

Over the past two decades, forecasting has gained widespread acceptance as an integral part of business planning and decision making. Accurate forecasting is a prerequisite to successful planning. Accordingly, recent advances in forecasting techniques are of exceptional value to corporate planners. But most of forecasting mothods are reveal its limit and problem for precision and reliability duing to each relationship for raw data and possibility of explanation for each variable. Therefore, to construct the Integrated Forecasting Model(IFM) for Information Factor Analysis, it shoud be considered that whether law data has time lag and variables are explained. For this. following several method can be used : Least Square Method, Markov Process, Fibonacci series, Auto-Correlation, Cross-Correlation, Serial Correlation and Random Walk Theory. Thus, the unified property of these several functions scales the safety and growth of the system which may be varied time-to-time.

• Journal of the Ergonomics Society of Korea
• /
• v.34 no.4
• /
• pp.293-302
• /
• 2015

Objective: This study was performed to investigate the prevalence of musculoskeletal disorders in auto workers of a mission assembly plants. Background: Most studies of musculoskeletal disorders have used car assembly line workers as their participants. However, little research has been done on musculoskeletal disorders afflictions of mission assembly line workers. Method: Through a focus group interview with an ergonomist and a manager at a mission assembly plant site, a questionnaire was developed for musculoskeletal disorders. The questionnaire consisted of five parts, demographic factors, musculoskeletal disorder symptoms, and musculoskeletal disorder experiences; 137 workers participated in this survey. The surveys were analyzed by correlation and Chi-squared analysis. Results: Musculoskeletal disorder symptoms and serious pain were reported in the neck, shoulder, back, and fingers. These problems were statistically related to various demographic factors, such as age, stature, stretching, and work satisfaction. Conclusion: Treatment of musculoskeletal disorders should consider the workers' traits. If there is no specific cause of the pain, developing stretches and exercises before and after work should be applied to prevent musculoskeletal disorders. Application: The results of this study can be used to develop guidelines to prevent injury in auto workers at mission assembly plants.

• Journal of Convergence for Information Technology
• /
• v.9 no.12
• /
• pp.54-61
• /
• 2019

Recently, IITS (intelligent integrated transportation system) has been important topic in Smart City related industry. As a main objective of IITS, prevention of traffic jam (due to car accidents) has been attempted with help of advanced sensor and communication technologies. Studies show that car accident has certain correlation with some factors including characteristics of location, weather, driver's behavior, and time of day. We concentrate our study on observing auto correlativity of car accidents in terms of time of day. In this paper, we performed the ARIMA tests including ADF (augmented Dickey-Fuller) to check the three factors determining auto-regressive, stationarity, and lag order. Summary on forecasting of hourly car crash counts is presented, we show that the traffic accident data obtained in Korea can be applied to ARIMA model and present a result that traffic accidents in Korea have property of being recurrent daily basis.

• Journal of Cardiovascular Imaging
• /
• v.31 no.3
• /
• pp.135-141
• /
• 2023

BACKGROUND: Global longitudinal strain (GLS) is an accurate and reproducible parameter of left ventricular (LV) systolic function which has shown meaningful prognostic value. Fast, user-friendly, and accurate tools are required for its widespread implementation. We aim to compare a novel web-based tool with two established algorithms for strain analysis and test its reproducibility. METHODS: Thirty echocardiographic datasets with focused LV acquisitions were analyzed using three different semi-automated endocardial GLS algorithms by two readers. Analyses were repeated by one reader for the purpose of intra-observer variability. CAAS Qardia (Pie Medical Imaging) was compared with 2DCPA and AutoLV (TomTec). RESULTS: Mean GLS values were -15.0 ± 3.5% from Qardia, -15.3 ± 4.0% from 2DCPA, and -15.2 ± 3.8% from AutoLV. Mean GLS between Qardia and 2DCPA were not statistically different (p = 0.359), with a bias of -0.3%, limits of agreement (LOA) of 3.7%, and an intraclass correlation coefficient (ICC) of 0.88. Mean GLS between Qardia and AutoLV were not statistically different (p = 0.637), with a bias of -0.2%, LOA of 3.4%, and an ICC of 0.89. The coefficient of variation (CV) for intra-observer variability was 4.4% for Qardia, 8.4% 2DCPA, and 7.7% AutoLV. The CV for inter-observer variability was 4.5%, 8.1%, and 8.0%, respectively. CONCLUSIONS: In echocardiographic datasets of good image quality analyzed at an independent core laboratory using a standardized annotation method, a novel web-based tool for GLS analysis showed consistent results when compared with two algorithms of an established platform. Moreover, inter- and intra-observer reproducibility results were excellent.

• Economic and Environmental Geology
• /
• v.39 no.3 s.178
• /
• pp.269-284
• /
• 2006

Aquifer responses to the river stage fluctuations were analyzed between the groundwater level and the river stage in an alluvial aquifer. The auto-correlation and cross-correlation as a time series analysis were applied. Study site is a floodplain in the Mangyeong river. Groundwater levels in each depth representing the silt and sand(SS), gravel and sand(GS), and weathered zone(WZ) layer were monitored. The groundwater levels were more sensitive to the river stage fluctuations than rainfall. Since the river stages are influenced by the gate operations downstream and tide, show periodic patterns, and the correlation coefficients with rainfall is low. Cross-correlation function between groundwater level in each depth do not show any delay time, then response time is very short to each depth. Cross-correlation analysis were performed to estimate the response time of groundwater levels to river stage fluctuations. Groundwater levels respond to the river stage within 30 minutes to 1 hour in wells near the stream. Short time lag between groundwater level and river stage indicates the quick response. A different response time imply the hydraulic inhomogeneity of the site, and a probable high permeability zone between river and aquifer can be inferred. Mangyeong-river in study site is a gaining stream normally, and river stage rising by gate operation or floods makes river water flow into groundwater. The auto-correlation and cross-correlation functions as a time series analysis can be a good tool to interpret the aquifer responses to stream stage fluctuation

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.9
• /
• pp.947-954
• /
• 2011

Drive-train friction loss in a vehicle may account for 4% of its total fuel consumption loss. An ATF W/C (auto-transmission fluid warmer/cooler) plate-fin heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between the auto-transmission fluid and coolant. The use of an ATF W/C heat exchanger can result in a fuel economy improvement of about 1% in vehicles. An experimental setup for testing the thermal performance of an ATF W/C plate-fin heat exchanger is developed. In this study, the influence of the ATF and coolant, flow rates, and temperature on the efficiency of an ATF W/C heat exchanger are investigated experimentally. From the experimental data, a simple correlation for predicting the efficiency of an ATF W/C heat exchanger is proposed. On the basis of this correlation, the fuel economy of a vehicle with and without an ATF W/C heat exchanger is compared by using Simulink. Finally, it is shown that the fuel economy is improved by 0.992% when an ATF W/C heat exchanger is installed in the vehicle.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.6 no.4
• /
• pp.539-544
• /
• 2011

Balanced binary sequences of period $2^n-1(n{\geq}1)$ having the two-valued autocorrelation function have many applications in spread-spectrum communications system. In this paper we propose new nonlinear binary sequences which are constructed from Legendre sequences with the same cross-correlation as the sequences proposed by Cho. These sequences include the m-sequences, GMW sequences, Kasami sequences and No sequences which are described in terms of the trace function over a finite field. Also the proposed sequences have more low cross-correlation distribution than the quadratic form sequences proposed by Klapper.

• Journal of the Korean housing association
• /
• v.19 no.2
• /
• pp.73-82
• /
• 2008

The purpose of this paper is to analyze the correlation analysis between the experienced crime victimization rate and the evaluation indicator of residents' safety of outdoor spaces from crime in multi-family housing. Additionally this paper intend to analyze the correlation analysis between the residents' satisfaction about safety and the evaluation indicator of residents' safety of outdoor spaces. For that purpose, 9 Multi-Family Housing located in the metropolitan area were selected to perform a survey against 349 residents during May 26-29, 2006. The SPSS program was used and the level of satisfaction ranged from 1 to 5. Scale of 5 being most satisfied while 1 being most dissatisfied. The results of this study are the followings; 1) Most occurred crime were auto theft and damages, poster matter theft, housebreaking. 2) The crime rate is higher in outdoor than in indoor. 3) This study proved the correlation between the residents' satisfaction about housing safety and most indicators except the number of households etc. 4) By the results of the correlation coefficient it makes clear that the number of apartment building, the visibility of Green Space, the location of pedestrian etc. have relation with the residents' satisfaction about housing safety.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.4C
• /
• pp.321-328
• /
• 2010

A Rayleigh fading channel simulator that realizes given correlation properties between two channels such as downlink/uplink is described. We propose an improved channel simulator that provides more accurate match between reference correlation and simulated one. The proposed channel simulator is based on a sum-of-sinusoids (SOS) method that handles finite sums of weighted sinusoid functions. SOS method is widely accepted in generating fading signals and obtain the exact match with the reference model if infinite number of weighted sinusoids are used. The proposed channel simulator minimizes mean-square-error (MSE) to obtain a close matched correlation properties.