• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.175-177
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• 2002

The use of underground transmission cables has increased continuously in densely inhabited urban and suburban for power transmission. Two or more transmission lines are outgoing from one substation in many cases, and one line comprises twin circuits. In order to meet the increasing do and for electric power, underground tables of two or fore circuits are installed in ducts in parallel for several kilometer in the same route. It, however, has not been known generally that the sheath circulating current is generated in a system where a large number of cables are laid on the same route. Therefore, this paper describes an improved analysis method for sheath circulating current on underground transmission cables using EMTP. Author propose several methods to reduce sheath circulating current. The analysing method and reduction methods for two or more underground cables will be really improved for cable system utility.

• 기술발표회
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• 통권2006호
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• pp.54-65
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• 2006

Since timbering of a cut in association with underground excavtion work is introduced to domestic, in spite of limitation of special quality in this method, time change, variety of construction, Strut Method is still considered with general methods. Experts have developed methods which is improved in limitation of special quality by continuous studies of normal strut method in basic, and it has been applied to construction site Consequently, this study introduced improved Strut Method to help experts when they select resonable methods with regard to construction site, conditions

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.465-468
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• 2006

This paper investigates the effect of curing conditions on the strength improvement of polymer-modified mortars using epoxy resin with various curing methods. The polymer-modified mortars using epoxy resin are prepared with various polymer-cement ratios, and subjected to standard, hot water, heat cure and autoclave cures. The epoxy-modified mortars are tested for flexural and compressive strengths at desired curing methods. From the test results, the flexural and compressive strengths of the epoxy-modified mortars are hardly improved by the autoclave and hot water cures compared to the ideal cure of $20^{\circ}C$. Among the four types of curing methods, the strengths of the heat cured epoxy-modified mortars is largely improved. Especially, it is obtained in the mortars sealed with PVDC film.

• Journal of information and communication convergence engineering
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• 제17권1호
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• pp.41-48
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• 2019

In recent years, sentiment analysis research has become popular. The research results of sentiment analysis have achieved remarkable results in practical applications, such as in Amazon's book recommendation system and the North American movie box office evaluation system. Analyzing big data based on user preferences and evaluations and recommending hot-selling books and hot-rated movies to users in a targeted manner greatly improve book sales and attendance rate in movies [1, 2]. However, traditional machine learning-based sentiment analysis methods such as the Classification and Regression Tree (CART), Support Vector Machine (SVM), and k-nearest neighbor classification (kNN) had performed poorly in accuracy. In this paper, an improved kNN classification method is proposed. Through the improved method and normalizing of data, the purpose of improving accuracy is achieved. Subsequently, the three classification algorithms and the improved algorithm were compared based on experimental data. Experiments show that the improved method performs best in the kNN classification method, with an accuracy rate of 11.5% and a precision rate of 20.3%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.3145-3162
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• 2023

As an important technology of the internetwork, wireless sensor network technique plays an important role in indoor localization. Non-line-of-sight (NLOS) problem has a large effect on indoor location accuracy. A location algorithm based on improved particle filter and directional probabilistic data association (IPF-DPDA) for WSN is proposed to solve NLOS issue in this paper. Firstly, the improved particle filter is proposed to reduce error of measuring distance. Then the hypothesis test is used to detect whether measurements are in LOS situations or NLOS situations for N different groups. When there are measurements in the validation gate, the corresponding association probabilities are applied to weight retained position estimate to gain final location estimation. We have improved the traditional data association and added directional information on the original basis. If the validation gate has no measured value, we make use of the Kalman prediction value to renew. Finally, simulation and experimental results show that compared with existing methods, the IPF-DPDA performance better.

• Asian Pacific Journal of Cancer Prevention
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• 제13권9호
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• pp.4521-4524
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• 2012

Object: In the present study, we compared the positive cytodiagnostic test rates with discrepancies using self-collection devices for cervical cancer screening. We made this survey to examine whether or not our self-smear preparation method using the Kato self-collection device contributed to an improved rate of detecting atypical cells compared with existing recommended preparation methods. Methods: Specimens were collected at 14 facilities handling self-collection methods, and samples were collected by a physician in 2 facilities. The chisquared test was performed using the SPSS ver. 20 statistical software to determine the relationships between the positive cytodiagnostic rate, specimen preparation methods, and self-collection devices. Results: Collecting cells using the Kato self-collection device and preparing liquid-based specimens, we obtained a significantly higher rate of positive cytodiagnosis and our results were equal to those obtained with the direct method. Conclusions: Taking into consideration increased needs for screening using the self-collection method in future, with even more improved test accuracy, a screening test that is acceptable to society needs to be established.

• 대한공간정보학회지
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• 제23권3호
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• pp.85-93
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• 2015

This paper mainly introduces the methods of extracting landslide information using ALOS(Advanced Land Observing Satellite) images and GIS(Geographical Information System) technology. In this study, we classified images using three different methods which are the unsupervised the supervised and the PCA(Principal Components Analysis) for extracting landslide information based on characteristics of ALOS image. From the image classification results, we found out that the quality of classified image extracted with PCA supervised method was superior than the other images extracted with the other methods. But the accuracy of landslide information extracted from this image classification was still very low as the pixels were very similar between the landslide and safety regions. It means that it is really difficult to distinguish those areas with an image classification method alone because the values of pixels between the landslide and other areas were similar, particularly in a region where the landslide and other areas coexist. To solve this problem, we used the LSM(Landslide Susceptibility Map) created with ArcView software through weighted overlay GIS method in the areas. Finally, the developed LSM was applied to the image classification process using the ALOS images. The accuracy of the extracted landslide information was improved after adopting the PCA and LSM methods. Finally, we found that the landslide region in the study area can be calculated and the accuracy can also be improved with the LSM and PCA image classification methods using GIS tools.

• Structural Engineering and Mechanics
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• 제54권3호
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• pp.561-577
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• 2015

The main objective of this paper is to study the dynamic load allowance (DLA) calculation methods for bridges according to the dynamic response curve. A simply-supported concrete bridge with a smooth road surface was taken as an example. A half-vehicle model was employed to calculate the dynamic response of deflection and bending moment in the mid-span section under different vehicle speeds using the vehicle-bridge coupling method. Firstly, DLAs from the conventional methods and code provisions were analyzed and critically evaluated. Then, two improved computing approaches for DLA were proposed. In the first approach, the maximum dynamic response and its corresponding static response or its corresponding minimum response were selected to calculate DLA. The second approach utilized weighted average method to take account of multi-local DLAs. Finally, the DLAs from two approaches were compared with those from other methods. The results show that DLAs obtained from the proposed approaches are greater than those from the conventional methods, which indicate that the current conventional methods underestimate the dynamic response of the structure. The authors recommend that the weighted average method based on experiments be used to compute DLAs because it can reflect the vehicle's whole impact on the bridge.

• Steel and Composite Structures
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• 제18권5호
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• pp.1197-1214
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• 2015

There is a great difference in mechanical behavior between design model one-time loading and step-by-step construction process. This paper presents practical computational methods for simulating the structural behavior of long-span rigid steel structures during construction processes. It introduces the positioning principle of node rectification for installation which is especially suitable for rigid long-span steel structures. Novel improved nonlinear analytical methods, known as element birth and death of node rectification, are introduced based on several calculating methods, as well as a forward iteration of node rectification method. These methods proposed in this paper can solve the problem of element's 'floating' and can be easily incorporated in commercial finite element software. These proposed methods were eventually implemented in the computer simulation and analysis of the main stadium for the Universiade Sports Center during the construction process. The optimum construction scheme of the structure is determined by the improved algorithm and the computational results matched well with the measured values in the project, thus indicating that the novel nonlinear time-varying analysis approach is effective construction simulation of complex rigid long-span steel structures and provides useful reference for future design and construction.

• 한국자동차공학회논문집
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• 제12권4호
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• pp.12-23
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• 2004

The effects of improved rice bran oil on the characteristics of exhaust emissions have been experimentally examined by a single cylinder, four cycle, direct injection, water-cooled agricul-tural diesel engine operating at several loads and speeds. The experiments are conducted with light oil, rice bran oil, and improved rice bran oil as a fuel. The fuel injection timing is fixed to 22$^{\circ}$ BTDC regardless of fuel types, engine loads and speeds. To reduce the viscosity of rice bran oil, it is used with the methods of heating, methyl ester and ultrasonic system in a highly viscous rice bran oil. In this study, it is found that the brake specific fuel consumption rate of light oil is the lowest and that of improved rice bran oils is lower than that of pure rice bran oil, and NO$_{x}$ emissions of light oil are the lowest and those of pure rice bran oil are the high- est, while soot emissions of light oil are the highest and those of pure and improved rice bran oils are lower than that of light oil. However these results are not amply satisfied with the emissions regulation limit using the pure and improved rice bran oil as fuels in diesel engines.s.