• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.527-535
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• 2003

In this paper, the performance of W-CDMA system with smart antenna is analyzed for angular spread in realistic wideband multipath channel. The realistic wideband channel is assumed, one of which is JTC channel model. And each multipath is assumed as a reflective wave from only one direction (only one cluster) in space. Several multipaths within one chip are distinguished into each one and the strongest signal is selected. As a result, the performance of the W-CDMA system with smart antenna in realistic wideband multipath channel has been considerably improved in proportion to the increase of angular spread.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.6
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• pp.480-494
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• 2009

Long term extreme wave data are essential for planning and designing coastal structures. Since the availability of the field data for the waters around Korean peninsula is limited to provide a reliable wave statistics, the wave climate information has been generated by means of long-term wave hindcasting using available meteorological data. KORDI(2005) has proposed extreme wave data at 106 stations off the Korean coast from 1979 to 2003. In this paper, extreme data sets of wave(KORDI, 2005) have been analyzed for best-fitting distribution functions, for which the spread parameter proposed by Goda(2004) is evaluated. The calculated values of the spread parameter are in good agreement with the values based on method of moment for parameter estimation. However, the spread parameter of extreme wave data has a representative value ranging from about 1.0 to 2.8 which is larger than some foreign coastal waters, it is necessary to review deep water design wave.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.3
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• pp.209-219
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• 2013

Epidemiological models on disease spread attempt to simulate disease transmission and associated control processes and such models contribute to greater understanding of disease spatial diffusion through of individual's contacts. The objective of this study is to develop an agent-based modeling(ABM) approach that integrates geographic information systems(GIS) to simulate the spread of FMD in spatial environment. This model considered three elements: population, time and space, and assumed that the disease would be transmitted between farms via vehicle along the roads. The model is implemented using FMD outbreak data in Andong city of South Korea in 2010 as a case study. In the model, FMD is described with the mathematical model of transmission probability, the distance of the two individuals, latent period, and other parameters. The results show that the GIS-agent based model designed for this study can be easily customized to study the spread dynamics of FMD by adjusting the disease parameters. In addition, the proposed model is used to measure the effectiveness of different control strategies to intervene the FMD spread.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.517-526
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• 2000

In this paper, we propose the trellis coded spread spectrum communication system with one channel signal selection of the subset by the PN code. This paper proposes the Viterbi decoder that have the squared Euclidean distance of the order phase difference as well as 1st order phase difference as the branch metrics by using the multiple symbol detection method. TCM method was developed to overcome limited power and bandwidth efficiently in digital communication. we multiply one of convolution code's output data to PN code for applying TCM to the spread spectrum. We investigated the performance of the direct sequence/spread spectrum communication system with trellis coded modulation. In this system, we could improved the coding gain in the spread spectrum.

• The Korean Journal of Pain
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• v.29 no.4
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• pp.255-261
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• 2016

Background: Thoracic epidural anesthesia is frequently used to maintain intraoperative and postoperative analgesia. Frequently, 3 ml of local anesthetic is used as a test dose, or for intermittent epidural injection. We assessed the extent of the spread of 3 ml of contrast medium in the thoracic epidural space and attempted to identify any correlating factors affecting the epidurography. Methods: A total of 70 patients were enrolled in the study, and thoracic epidural catheterizations were performed under fluoroscopic guidance. Using 3 ml of contrast medium, epidurography was evaluated to confirm the number of spinal segments covered by the contrast medium. Correlation analysis was performed between patient characteristics (sex, age, body mass index, weight, height, and location of catheter tip) and the extent of the contrast spread. Results: The mean number of vertebral segments evaluated by contrast medium was $7.9{\pm}2.2$ using 3 ml of contrast medium. The contrast spread in the cranial direction showed more extensive distribution than that in the caudal direction, with statistical significance (P < 0.01). Patient height demonstrated a negative correlation with the extent of distribution of contrast medium (r = -0.311, P < 0.05). Conclusions: Thoracic epidurography using 3 ml of contrast medium results in coverage of a mean of $7.9{\pm}2.2$ spinal segments, with more extensive cranial spread, and patient height showed a weak negative correlation with the distribution of contrast medium.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.1
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• pp.1-8
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• 2011

In this paper, a water tank experiment using Binary Frequency Shift Keying (BFSK) method for text transmission performance by water surface fluctuation is conducted. Water surface fluctuation and delay spread which affect the channel coherence bandwidth is a limiting factor in underwater acoustic communication. The amplitude fluctuation and delay spread the smooth surface and fluctuation surface, were identified. The effective delay spread of both cases are 5ms, 4ms corresponding to the coherence bandwidth of 200Hz, 250Hz, respectively. The bit error rate of BFSK modulated text transmission is about $10^{-4}$ in less than 200bps in smooth surface but less than 250bps in fluctuation surface. Therefore, this experiment shows that the water surface fluctuation is important factor determining the performance of the underwater acoustic transmission.

• 한국벤처창업학회:학술대회논문집
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• 2007.11a
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• pp.81-109
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• 2007

The loan rate of the government loan program offered by the Small Business Corporation(SBC) can be determined as a sum of three factors such as a reference interest rate, a policy aim spread, and a credit risk spread. However the loan rate has been lower than the loan rate in the banking sector. The profit has continually run in the red figures and hence the stability the fund managed by the SBC has been damaged. Even though a policy aim spread could be emphasized, the stability and profitability of the fund should be prioritized. This means that the loan rate of the SBC should be determined such that the loss might not be occurred. This requires the policy aim spread to change from relatively large negative to near zero.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.2
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• pp.132-136
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• 1990

This experiment was conducted to study the multiplication and spread of bacterial population in water exuded through the hydathode of infected leaf of Xanthomonas campestris pv. oryzae in resistant and susceptible rice cultivars to bacterial leaf blight. The results obtained are summarized as follows. The bacterial multiplication in resistant cultivars was almost constant from three days to twelve days after inoculation with population of 10$^3$-10$^4$cfu/$\textrm{cm}^2$, but the multiplication was increased as days after inoculation extended in susceptible cultivars. The speed of bacterial multiplication and the number of bacteria spread above and below the inoculated position were closely related with the resistance of rice cultivars to bacterial leaf blight. The bacterial multiplication and spread were observed throughout the all growing stages including seedling, maximum tillering and flag leaf stages. The bacterial populations in water exuded through the hydathode were dependent on the multiplication and spread, and the populations were also closely related with the resistance of rice cultivars.

• Journal of Korean Society of Forest Science
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• v.95 no.3
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• pp.240-249
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• 2006

Recently, dispersion of damaged forest by pine wilt disease has been regarded as a serious social issue. Damages by pine wilt disease have been spreaded by natural area expansion of the vectors in the damaged area, while the national wide damage spread has induced by human-involved carrying infected trees out of damaged area. In this study, damaged trees were detected and located on the digital map by aerial photograph and terrestrial surveys. The spatial distribution pattern of damaged trees, and the relationship of spatial distribution of damaged trees and some geomorphological factors were geostatistically analysed. Finally, we maked natural spread pattern map of pine wilt disease using geostatistical CART(Classification and Regression Trees) model. This study verified that geostatistical analysis and CART model are useful tools for understanding spatial distribution and natural spread pattern of pine wilt diseases.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.10
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• pp.1-7
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• 2010

A new frequency offset estimation algorithm for chirp spread spectrum based on matched filter is proposed. Generally, the differential phase between successive symbols is used for the conventional frequency offset estimation algorithm. However, if the conventional frequency offset estimation algorithm is used for CSS, phase ambiguity arises because of long symbol duration and guard time. The phase ambiguity causes performance degradation of matched filter since the received signal is corrupted by the integer frequency offset. In this paper, we propose a new frequency offset estimation algorithm which separates integer and fractional frequency offset estimation for removing the phase ambiguity. The proposed algorithm estimates the integer frequency offset by using differential phase between matched filtering results of sub-chirps and successive symbols. Then, the fractional frequency offset is estimated by using the differential phase between successive symbols Simulation results show that the proposed algorithm well removes the phase ambiguity, and have almost same estimation performance compared with conventional one when there is not the phase ambiguity.