• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.2
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• pp.227-238
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• 2006

Line density index(LDI) was developed to quantify a densely isothermal line rate as standard index in the ocean environment. Theoretical background on the LDI development process restricting index range 0 to 100 was described. And validation test was done for the LDI application condition that total line length is not greater than 1/10 of unit area. NOAA SST(Sea Surface Temperature) data were used for the experimental application of LDI in the South Sea of Korea. Using GIS, $0.1^{\circ}C$ isothermal lines were linearized as vector data form SST raster data, and unit area were built as polygon data. For the LDI calculation, spatial overlapping(line in polygon) was implemented. To analyze the effect of unit area size for the LDI distribution, two cases of unit area size were designed and descriptive statistics was calculated including performing normality test. The results showed no change of LDI's essential characteristics such as mean and normality except for the range of value, variance and standard deviation. Accordingly, it was found that complex structure of thermal front and even smaller scale of front width than unit area size could influence on the LDI distribution. Also, correlation analysis performed between LDI and difference of temperature(${\Delta}T^{\circ}C$), and horizontal thermal gradient(${\Delta}T^{\circ}C/km$) on the front was obtained from linear regression model. This obtained value was compared with the results from previous researches. Newly developed LDI can be used to compare the thermal front regions changing spatio-temporally in the ocean environment using absolute index value. It is considered to be significant to analyze the relationship between thermal front and marine environment or front and marine organisms in a quantitative approach described in this study.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.97-103
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• 2004

In this paper, we propose a high speed block turbo code decoding algorithm and an efficient hardware architecture. The multimedia wireless data communication systems need channel codes which have the high-performance error correcting capabilities. Block turbo codes support variable code rates and packet sizes, and show a high performance due to a soft decision iteration decoding of turbo codes. However, block turbo codes have a long decoding time because of the iteration decoding and a complicated extrinsic information operation. The proposed algorithm using the threshold that represents a channel information reduces the long decoding time. After the threshold is decided by a simulation result, the proposed algorithm eliminates the calculation for the bits which have a good channel information and assigns a high reliability value to the bits. The threshold is decided by the absolute mean and the standard deviation of a LLR(Log Likelihood Ratio) in consideration that the LLR distribution is a gaussian one. Also, the proposed algorithm assigns '1', the highest reliable value, to those bits. The hardware design result using verilog HDL reduces a decoding time about 30% in comparison with conventional algorithm, and includes about 20K logic gate and 32Kbit memory sizes.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.8
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• pp.117-125
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• 2015

In this paper, we propose a classification algorithm based on the obtained EEG(Electroencephalogram) signal for the control of 'left' and 'right' turnings of which a driving system composed of EEG sensor, Labview, DAQ, Matlab and driving robot. The proposed algorithm uses features extracted from frequency band information obtained by DWT (Discrete Wavelet Transform) and selects features of high discrimination by using Fisher score. We, also propose the number of feature vectors for the best classification performance by using SVM(Support Vector Machine) classifier and propose a decision pending algorithm based on MLD (Maximum Likelihood Decision) to prevent malfunction due to misclassification. The selected four feature vectors for the proposed algorithm are the mean of absolute value of voltage and the standard deviation of d5(2-4Hz) and d2(16-32Hz) frequency bands of P8 channel according to the international standard electrode placement method. By using the SVM classifier, we obtained 98.75% accuracy and 1.25% error rate. Also, when we specify error probability of 70% for decision pending, we obtained 95.63% accuracy and 0% error rate by using the proposed decision pending algorithm.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.1861-1864
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• 2016

Although early diagnosis of thyroid nodule type is very important, the diagnostic accuracy of standard tests is a challenging issue. We here aimed to find an optimal combination of factors to improve diagnostic accuracy for distinguishing malignant from benign thyroid nodules before surgery. In a prospective study from 2008 to 2012, 345 patients referred for thyroidectomy were enrolled. The sample size was split into a training set and testing set as a ratio of 7:3. The former was used for estimation and variable selection and obtaining a linear combination of factors. We utilized smoothly clipped absolute deviation (SCAD) logistic regression to achieve the sparse optimal combination of factors. To evaluate the performance of the estimated model in the testing set, a receiver operating characteristic (ROC) curve was utilized. The mean age of the examined patients (66 male and 279 female) was $40.9{\pm}13.4years$ (range 15- 90 years). Some 54.8% of the patients (24.3% male and 75.7% female) had benign and 45.2% (14% male and 86% female) malignant thyroid nodules. In addition to maximum diameters of nodules and lobes, their volumes were considered as related factors for malignancy prediction (a total of 16 factors). However, the SCAD method estimated the coefficients of 8 factors to be zero and eliminated them from the model. Hence a sparse model which combined the effects of 8 factors to distinguish malignant from benign thyroid nodules was generated. An optimal cut off point of the ROC curve for our estimated model was obtained (p=0.44) and the area under the curve (AUC) was equal to 77% (95% CI: 68%-85%). Sensitivity, specificity, positive predictive value and negative predictive values for this model were 70%, 72%, 71% and 76%, respectively. An increase of 10 percent and a greater accuracy rate in early diagnosis of thyroid nodule type by statistical methods (SCAD and ANN methods) compared with the results of FNA testing revealed that the statistical modeling methods are helpful in disease diagnosis. In addition, the factor ranking offered by these methods is valuable in the clinical context.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.2
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• pp.151-161
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• 2007

Statistical characteristic analysis was carried out using the non-tidal components computed by the harmonic analysis of the tidal elevation data in East coast. The tide gauging stations included in this study are the Sokcho, Mukho, Hupo, Pohang, Ulsan and Ulreungdo stations. In this study, the variance and skewness coefficient (SC) information changes, i.e., the max. value, min. value, mean and standard deviation of the variance and SC, are compared and analysed in detail by the various analysis periods increased from one year to the maximum available period. Based on the result of the statistical information (SI) range analysis, the minimum analysis period required in order to satisfy the confidence interval of the ${\pm}5%$ range of the variance and the ${\pm}0.1$ range of the SC is suggested as the 12 years, except the Ulreungdo stations. The auto-correlation and spectral density change patterns show the very similar shapes in every stations even though the absolute values are a little bit different each other.

• Journal of Korean Society of Forest Science
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• v.108 no.4
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• pp.592-599
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• 2019

This study aimed to develop an equation for estimating stem volume for Larix kaempferiin South Korea using independent variables, diameter at breast height (DBH), and height as being closely associated with stem volume. Analysis was conducted on the growth performance of 2,840 Larix kaempferi samples across South Korea after felling them and gleaning diameter data according to both stem height and stem analyses. In order to test the fitness of six different stem taper equations, empirical assessment was conducted for fitness index (FI), bias, mean, and absolute deviation (MAD), and coefficient variation (%CV). The two selectedmodels found to be optimal were the following: model one (V=a+bDBH²), established by employing DBH only; and model four (V=a+bDBH²H), established by utilizing DBH and height, respectively. The findings of non-linear regression indicated statistical significance (p < 0.05) in a and b, which were the coefficients for the intercepts and slopes of the models. The FI of the models ranged between 94% and 99%, and the bias was close to zero, while MAD ranged from 0.01 to 0.05, and %CV from 5.97 to 14.43, indicating a high level of fitness. Thus, using the suggested models, the basic information necessary for forest management was obtained, and an estimation of the stem volume was effected without delay soon after effecting DBH and height measurements.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.411-417
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• 2000

This paper describes the analysis of the oscillometric method based on the shape of arterial pressure and proposal of a new algorithm for estimating the blood pressure by computer simulation. In the first step, the arterial pressure model which is able to control the shape of arterial pressure was designed and then we simulated the oscillometric model using both the existing exponential model showing the static arterial pressure-volume relation and the designed arterial pressure model. By analyzing the correlation of characteristic ratio based on the shape of arterial pressure, we could find that the characteristic ratio was not the only standard parameter for estimating systolic and diastolic pressure. We were able to estimate the shape of arterial pressure by computing the correlation of arterial pressure shape with oscillation shape. Finally, we proposed an algorithm which is able to estimate systolic and diastolic pressure according to pressure(Pp) table constructed from the relation of maximum amplitude of oscillation and arterial pressure shape. We tested 60 arterial pressure waveforms having various arterial pressure shape and pulse. As a results, the absolute deviation average values of the estimation of systolic, diastolic and mean pressure were 1.62%, 2.40% and 2.20%, respectively. In conclusions, the proposed algorithm showed the possibility of usefullness in estimating the blood pressure.

• Journal of Korean Society for Quality Management
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• v.47 no.1
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• pp.47-57
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• 2019

Purpose: This paper aims to investigate the concentration of fine particulate matter (PM2.5) in the Seoul area by predicting unhealthy days due to PM2.5 and comparing the regional differences. Methods: The extreme value theory is adopted to model and compare the PM2.5 concentration in each region, and each best model is selected through the goodness of fitness test. The maximum likelihood estimation technique is applied to estimate the parameters of each distribution, and the fitness of each model is measured by the mean absolute deviation. The selected model is used to estimate the number of unhealthy days (above $75{\mu}g/m^3$ PM2.5 concentrations) in each region, with which the actual number of unhealthy days are compared. In addition, the level of PM2.5 concentration in each region is analyzed by calculating the return levels for periods of 6 months, 1 year, 3 years, and 5 years. Results: The Mapo (MP) area revealed the most unhealthy days, followed by Gwanak (GW) and Yangcheon (YC). On the contrary, the number of unhealthy days was low in Seodaemun (SDM), Songpa (SP) and Gangbuk (GB) areas. The return level of PM2.5 was high in Gangnam (GN), Dongjak (DJ) and YC. It will be necessary to prepare for PM2.5 than other regions. On the contrary, Gangbuk (GB), Nowon (NW) and Seodaemun (SDM) showed relatively low return levels for PM2.5. However, in most of the regions of Seoul, PM25 is generated at a very poor level ($75{\mu}g/m^3$) every 6months period, and more than $100{\mu}g/m^3$ PM2.5 occur every 3 years period. Most areas in Seoul require more systematic management of PM2.5. Conclusion: In this paper, accurate prediction and analysis of high concentration of PM2.5 were attempted. The results of this research could provide the basis for the Seoul Metropolitan Government to establish policies for reducing PM2.5 and measuring its effects.

• Journal of Korean Society of Forest Science
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• v.109 no.4
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• pp.461-467
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• 2020

The aim of this study was to utilize Kozak's stem taper model to develop both a stem taper equation and a stem volume table for Criptomeria japonica, a tree species distributed across Korea. A total of 1,000 sample trees were cut and collected across the country to measure their diameters by stem height. The equation was then used to estimate examine their stem shapes. Our results show that the Fitness Index for the equation was 98.7%, the Mean Absolute Deviation (MAD) was -0.0142, and the MAD was 1.1640, thus indicating a high level of fitness. A statistically significant difference (p < 0.05) was also found from the analysis of discrepancies between a current table and the new table used in this study. It is therefore suggested that the new table-with data from actual stands-will contribute to enhancing the accuracy of national and municipal forest statistics and reducing losses caused by imprecise data on available forest resources.

• Korean Journal of Radiology
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• v.22 no.12
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• pp.1996-2005
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• 2021

Objective: To investigate the multidetector computed tomography (MDCT) features of fumarate hydratase-deficient renal cell carcinoma (FH-deficient RCC) with germline or somatic mutations, and compare them with those of papillary type II RCC (pRCC type II). Materials and Methods: A total of 24 patients (mean ± standard deviation, 40.4 ± 14.7 years) with pathologically confirmed FH-deficient RCC (15 with germline and 9 with somatic mutations) and 54 patients (58.6 ± 12.6 years) with pRCC type II were enrolled. The MDCT features were retrospectively reviewed and compared between the two entities and mutation subgroups, and were correlated with the clinicopathological findings. Results: All the lesions were unilateral and single. Compared with pRCC type II, FH-deficient RCC was more prevalent among younger patients (40.4 ± 14.7 vs. 58.6 ± 12.6, p < 0.001) and tended to be larger (8.1 ± 4.1 vs. 5.4 ± 3.2, p = 0.002). Cystic solid patterns were more common in FH-deficient RCC (20/24 vs. 16/54, p < 0.001), with 16 of the 20 (80.0%) cystic solid tumors having showed typical polycystic and thin smooth walls and/or septa, with an eccentric solid component. Lymph node (16/24 vs. 16/54, p = 0.003) and distant (11/24 vs. 3/54, p < 0.001) metastases were more frequent in FH-deficient RCC. FH-deficient RCC and pRCC type II showed similar attenuation in the unenhanced phase. The attenuation in the corticomedullary phase (CMP) (76.3% ± 25.0% vs. 60.2 ± 23.6, p = 0.008) and nephrographic phase (NP) (87.7 ± 20.5, vs. 71.2 ± 23.9, p = 0.004), absolute enhancement in CMP (39.0 ± 24.8 vs. 27.1 ± 22.7, p = 0.001) and NP (50.5 ± 20.5 vs. 38.2 ± 21.9, p = 0.001), and relative enhancement ratio to the renal cortex in CMP (0.35 ± 0.26 vs. 0.24 ± 0.19, p = 0.001) and NP (0.43 ± 0.24 vs. 0.29 ± 0.19, p < 0.001) were significantly higher in FH-deficient RCC. No significant difference was found between the FH germline and somatic mutation subgroups in any of the parameters. Conclusion: The MDCT features of FH-deficient RCC were different from those of pRCC type II, whereas there was no statistical difference between the germline and somatic mutation subgroups. A kidney mass with a cystic solid pattern and metastatic tendency, especially in young patients, should be considered for FH-deficient RCC.