• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.746-753
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• 2017

Radar Cross Section (RCS) is a factor directly related to survivability, and a design to reduce the presence of this factor is needed. The upper structure, guns, radar and so on are related to warship RCS, but radar RCS reduction is difficult because of complex shapes involved. In this paper, an enclosed mast, which is one modern method for reducing radar RCS, and the characteristics of an applied Frequency Selected Surface (FSS) are analyzed. The RCS reduction ability of an enclosed mast has been confirmed by comparing RCS analysis results for a general radar with that of an enclosed mast for available frequency according to FSS shape. The characteristics of the enclosed mast have also been studied by analyzing the elevation angle and slope of the mast. General radar RCS was high because of its complex shape, but low RCS was shown for the enclosed mast model, which had a simpler shape.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.911-917
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• 2023

The method of observing nodular changes on the liver surface using clinical ultrasonography is useful for diagnosing cirrhosis. However, the speckle noise that inevitably occurs in ultrasound images makes it difficult to identify changes in the liver surface and echo patterns, which has a negative impact on the diagnosis of cirrhosis. The purpose of this study is to model the median modified Wiener filter (MMWF), which can efficiently reduce noise in cirrhotic ultrasound images, and confirm its applicability. Ultrasound images were acquired using an ACR phantom and an actual cirrhotic patient, and the proposed MMWF algorithm and conventional noise reduction algorithm were applied to each image. Coefficient of variation (COV) and edge rise distance (ERD) were used as quantitative image quality evaluation factors for the acquired ultrasound images. We confirmed that the MMWF algorithm improved both COV and ERD values compared to the conventional noise reduction algorithm in both ACR phantom and real ultrasound images of cirrhotic patients. In conclusion, the proposed MMWF algorithm is expected to contribute to improving the diagnosis rate of cirrhosis patients by reducing the noise level and improving spatial resolution at the same time.

• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.770-778
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• 2023

Purpose: In order to reduce forklift industrial accidents, it is necessary to classify them into institutional, technical, and educational factors and conduct research on whether each factor affects disaster reduction. Method: Descriptive statistical analysis, validity analysis, reliability analysis, and multiple regression analysis were conducted using SPSS 18 program based on an offline questionnaire based on a 5-point Likert scale. Result: As a result of multiple regression analysis, it was found that institutional, technical, and educational factors, which are independent variables for disaster reduction, explain about 62.5% of the variance in disaster prevention, which is the dependent variable. The regression model verification was found to be statistically significant with F=118.775 and significance probability p<0.01. Conclusion: First, there is a need to prevent disasters by including electric forklifts weighing less than 3 tons in the inspection system. Second, there is a need to make it mandatory to install front and rear cameras and forklift line beams to prevent forklift collision disasters. Third, there is a need to conduct special training related to forklifts every year, and drivers and nearby workers need to be included in the special training for forklifts.

• The Korea Journal of Herbology
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• v.30 no.6
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• pp.39-46
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• 2015

Objectives : The aim of this study was to evaluate the effect of Schizonepeta Spica water extract (SS) on the OVA-induced BLAB/c mice allergic rhinitis model.Methods : Thirty two BALB/c mice were equally assigned to 4 groups; the sham group, the control group, the cetirizine hydrochloride (Cet) treatment group, and the SS treatment group. Sham group was sensitized and challenged with saline, and the other groups were sensitized and challenged with OVA. The dosage of SS was 7.6 mg /kg·day, and Cet was 10 mg/kg·day. Nasal rubbing and sneezing were measured by the behavior observation. The concentrations of IL-1β, IL-10, TNF-α and MIP-2 in the sera of allergic rhinitis model were measured by mouse cytokine/chemokine magnetic bead panel kits. Total IgE and OVA-specific IgE were measured by ELISA method. Epithelial thickness and eosinophil infiltration of nasal septum was investigated by histological examination.Results : The clinical symptoms that increased in control group were significantly reduced in SS-treated group. Serum total IgE and OVA-specific IgE in the SS-treated group were significantly reduced compared to the control group. The concentration of IL-1β, IL-10, TNF-α and MIP-2 in SS-treated group showed a significant reduction compared to the control group. The infiltration of eosinophil into nasal tissues of SS-treated group decreased markedly compared to control group, and thickness of nasal septum in nasal mucosa showed a significant reduction compared to control group.Conclusions : According to the above result, it is suggested that SS may inhibit the early and late phase of allergic rhinitis reaction.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.698-709
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• 2023

Purpose: In this paper, we would like to analyze the growth rate of existing urban immersion in the downstream during large-scale urban development and the degree of reduction in existing urban immersion in the downstream when small excellent storage facilities are planned in apartment complexes. Method: A large-scale sewage model was built using the SWMM model of the U.S. Environmental Protection Agency, and the impact of flooding in existing downtown areas downstream was analyzed through simulation. The built model included the development zone, the existing downtown area downstream, and the entire river basin that discharges rainwater. Result: As a result of calculating and simulating the minimum excellent reservoir capacity for each apartment block in the study target area, it was found that the immersion of 4,893㎥ based on one hour, 25,815㎥ based on two hours, and 55,528㎥ based on three hours in the downstream urban area. Conclusion: As in this study, large-scale flooding simulation considering the existing downtown area in the downstream shows a significant increase in flooding in the downstream, and if excellent reservoir capacity is planned for each apartment block before development and the construction of excellent reservoirs is recommended.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.5
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• pp.105-112
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• 2011

Delay reduction of vehicles at the intersection is highly dependent on the signal operation method. Improper traffic operation causes the violation of the traffic regulations and increasing traffic congestion. Delay because of congestion has contributed to the increase in carbon dioxide in the atmosphere. The focus of this paper is to measure the amount of carbon dioxide when the intersection is changed to roundabout. Even though, Intergovernmental Panel on Climate Change(IPCC) recommends Tier 1 method to measure the amount of greenhouse gas from vehicles, this paper used Tier 3 method because we could use the data of average running distance per each vehicle model. Two signalized intersections were selected as the study area and the delay reductions of roundabout operation were estimated by VISSIM microscopic simulation tool. The control delay for boksu intersection reduced from 28.6 seconds to 4.4 seconds and the KRIBB intersection sharply reduced from 156.4 seconds to 23.6 seconds. In addition, carbon dioxide for two intersections reduced to 646.5 ton/year if the intersection is changed to roundabout. Future research tasks include testing the experiment for networks, as well as for various intersection types.

• Geomechanics and Engineering
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• v.7 no.5
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• pp.495-524
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• 2014

To investigate the soil-pile interactive performance under lateral loads, a set of laboratory model tests was conducted on remoulded test bed of soft clay and medium dense sand. Then, a simplified boundary element analysis had been carried out assuming floating pile. In case of soft clay, it has been observed that lateral loads on piles can initiate the formation of a gap, soil heave and the tension crack in the vicinity of the soil surface and the interface, whereas in medium dense sand, a semi-elliptical depression zone can develop. Comparison of test and boundary element results indicates the accuracy of the solution developed. However, in the boundary element analysis, the possible shear stresses likely to be developed at the interface are ignored in order to simplify the existing complex equations. Moreover, it is unable to capture the influence of base restraint in case of a socketed pile. To bridge up this gap and to study the influence of the initial stress state and interface parameters, a field based case-study of laterally-loaded pile in layered soil with socketed tip is explored and modelled using the finite element method. The results of the model have been verified against known field measurements from a case-study. Parametric studies have been conducted to investigate the influence of the coefficient of lateral earth pressure and the interface strength reduction factor on the results of the model.

• Ocean Science Journal
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• v.42 no.4
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• pp.211-222
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• 2007

We compare insolation results calculated from two well-known empirical formulas (Socket and Beaudry's SB73 formula and the original Smithsonian (SMS) formula) and a radiative transfer model using input data predicted from meteorological weather-forecast models, and review the accuracy of each method. Comparison of annual mean daily irradiance values for clear-sky conditions between the two formulas shows that, relative to the SMS, the SB73 underestimates spring values by 9 W $m^{-2}$ in the northern Adriatic Sea, although overall there is a good agreement between the annual results calculated with the two formulas. We also elucidate the effect on SMS of changing the 'Sun-Earth distance factor (f)', a parameter which is commonly assumed to be constant in the oceanographic context. Results show that the mean daily solar radiation for clear-sky conditions in the northern Adriatic Sea can be reduced as much as 12 W $m^{-2}$ during summer due to a decrease in the f value. Lastly, surface irradiance values calculated from a simple radiative transfer model (GM02) for clear-sky conditions are compared to those from SB73 and SMS. Comparison with iu situ data in the northern Adriatic Sea shows that the GM02 estimate gives more realistic surface irradiance values than SMS, particularly during summer. Additionally, irradiance values calculated by GM02 using the buoy meteorological fields and ECMWF (The European Centre for Medium Range Weather Forecasts) meteorological data show the suitability of the ECMWF data usage. Through tests of GM02 sensitivity to key regional meteorological factors, we explore the main factors contributing significantly to a reduction in summertime solar irradiance in the Adriatic Sea.

• The KIPS Transactions:PartB
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• v.11B no.4
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• pp.485-490
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• 2004

In data representation, the clustering performs a grouping process which combines given data into some similar clusters. The various similarity measures have been used in many researches. But, the validity of clustering results is subjective and ambiguous, because of difficulty and shortage about objective criterion of clustering. The fuzzy clustering provides a good method for subjective clustering problems. It performs clustering through the similarity matrix which has fuzzy membership value for assigning each object. In this paper, for objective fuzzy clustering, the clustering algorithm which joins principal components analysis as a dimension reduction model with bayesian learning as a statistical learning theory. For performance evaluation of proposed algorithm, Iris and Glass identification data from UCI Machine Learning repository are used. The experimental results shows a happy outcome of proposed model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10B
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• pp.1971-1978
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• 1999

In this paper, we study the effects of long-range dependence (LRD) in VBR video traffic on queueing system. This paper consists of Part I and II. In Part I, we present a (LRD) video traffic model based on the shifting-level (SL) process. We observe that the ACF of an empirical video trace is accurately captured by the shifting-level process with compound correlation (SLCC): an exponential function in short range and a hyperbolic function in long range. We present an accurate parameter matching algorithm for video traffic. In the Part II, we offer the queueing analysis of SL/D/1/K called ‘quantization reduction method’. Comparing the queueing performances of the DAR(1) model and the SLCC with that of a real video trace, we identify the effects of SRD and LRD in VBR video traffic on queueing performance. Simulation results show that Markoivian models can estimate network performances fairly accurately under a moderate traffic load and buffer condition, whereas LRD may have a significant effect on queueing behavior under a heavy traffic load and large buffer condition.