• The Journal of the Korea Contents Association
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• v.18 no.9
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• pp.433-440
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• 2018

I investigated whether network structure of legislators affects legislative performance in a cosponsorship network. I presented the theoretical basis with network closure and structural holes, and analyzed the network in the 19th National Assembly of Republic of Korea. In the directed and weighted network, each tie means that cosponsors support the bill sponsors proposed. The performance was measured by the number of initiatives and the ratio of reflected legislation, and the network structure was measured by size, density, hierarchy, and constraint. I found that the legislators with brokerage structure have a lot of initiatives in making connection with many legislators in various groups and the legislators with hierarchical structure have the higher ratio of reflected legislation with the continuous and strong support from the members of their group. I also found that the network of ruling party lawmaker is more hierarchical than the network of opposition lawmaker.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.9
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• pp.361-366
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• 2018

Previous studies on fear of crime used survey and interview to measure fear of crime. However, though these methods can measure fear of crime in past events, they cannot measure real time fear of crime. In this paper, we use EEG to measure fear of crime in real time. We measure and analyze the EEG of subjects watching the video and confirm the difference between three groups classified according to the degree of fear of crime. As a result, about two times more beta waves are shown when a group of subjects with a high degree of fear of crime watches the images of fear of crime and 1.5 times more beta waves are shown among the other groups. Although watching videos related to the crime increased the beta waves, the police video showed little increase in beta waves because the subjects can sense safety in the video even if it is related to crime.

• Journal of Digital Contents Society
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• v.18 no.1
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• pp.175-182
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• 2017

Noises are usually generated by various external causes and low quality devices in image data acquisition and recording as well as by channel interference in image transmission. Since these noise signals result in the loss of information, subsequent image processing is subject to the corruption of the original image. In general, image processing is performed in the mixed noise environment where common types of noise, known to be Gaussian and impulse, are present. This study proposes an iterative weighted mean filter for reducing mixed type of noise. Impulse noise pixels are first turned off in the input image, then $3{\times}3$ sliding window regions are processed by replacing center pixel with the result of weighted mean mask operation. This filtering processes are iterated until all the impulse noise pixels are replaced. Applied to images corrupted by Gaussian noise with ${\sigma}=10$ and different levels of impulse noise, the proposed filtering method improved the PSNR by up to 12.98 dB, 1.97 dB, 1.97 dB respectively, compared to SAWF, AWMF, MMF when impulse noise desities are less than 60%.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.103-112
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• 2005

Water content of sub-layer in pavement systems has a large effect on pavement performance. Many researchers lately make use of time-domain reflectometry(TDR) probes to measure the soil water content of sub-layer from field monitoring. The laboratory calibration test of TDR probe should be performed with soil field, because TDR probe can cause an error by type, gradation, density, and temperature of soil. This study performed the laboratory calibration test of TDR probe(CS616) with subgrade and subbase material in long term pavement performance(LTPP) sections. And the calibration equations of TDR probe(CS616) were then proposed. It was confirmed from the study that the data of TDR probe monitored in field could be used to estimate the freezing, unfrozen water content, and matric suction of soil.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.151-156
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• 2017

In case of massive water leakage, it's crucial for field manager to quickly positioning the problematic valve and related ones. However, it's not easy for the system to find the corresponding valve and even if it's found, it can not respond quickly because it can't know the relevant information immediately. In this paper, we implement the system for identifying sluice valve positions using GPS and AR techniques. The proposed system is composed of hand held android device, remote database server and data acquisition device for DB creation. We utilize the android device's sensors including GPS, gyro, accelerometer, magnetic sensor. The system identifies the valve with matching between the position data from the remote database server, and current GPS locations of device. We use AR techniques to overlay the graphics pattern of valve positions and some additional informations on captured real scene. With this system, it will be fast and accurate for maintenance of sluice valve of municipal water system.

• Journal of the Korean Data and Information Science Society
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• v.28 no.1
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• pp.67-74
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• 2017

This paper analyzes the causal relationship from climate to international grain prices. Although climate is an important factor affecting the grain markets, it has been restrictively considered in previous studies analyzing the causal relationship of international grain prices. In this paper, monthly data from May 1987 to 2013 is used for the causal analysis in which the sea surface temperature (SST), a representative global climate variable, and the international prices of wheat, corn, and soybean, the world's three major crops, are considered. The test method is the parametric version of the nonparametric test for causality in high-order moments suggested by Nishiyama et al. (2011). The results show that the climate causes in the first moment the prices of all the three grains and causes in the second moment the prices of corn and soybean, but does not cause in the third moment any of the three grain prices.

• Clean Technology
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• v.12 no.3
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• pp.182-189
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• 2006

In this study, high speed machining is evaluated with regard to economical and environmental effects. Considering environmental loads, machining costs are analyzed with the mathematical models of machining economics and cutting fluid loss. Data from the tool life experiments of high speed milling and turning are used for the analysis. The analysis of high speed milling shows that the machining cost decreases as increasing the cutting speed. In turning process, the cooling method using cutting fluid shows the minimum machining cost. Considering both machining and environmental costs, cooling method using cold air is superior to other methods.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.95-105
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• 2004

The fundamental diagram is a important element in a variety of transportation studies. While various shapes of the fundamental diagram have been proposed and numerous debates on the best-fit fundamental diagram have been made, the reason why the fundamental diagram has many different shapes has not been well explained. This study introduces time sap as a key parameter to understand drivers' behavioral differences at different locations and traffic conditions, then relate to the shape of the fundamental diagram. From the freeway event detector data, it is shown that time gap follows a certain probabilistic distribution and its mean value varies along locations. It also turns out that drivers take different time gaps for different travel speeds. Three different types of time gap-speed diagrams are identified and matched to Greenberg, reversed-lambda, and inverted-V types of fundamental diagrams, respectively. This study explains the characteristics of fundamental diagrams using time gap as a microscopic variable and describes drivers' behavioral characteristics according to traffic and geometric conditions.

• Journal of Korean Society of Transportation
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• v.33 no.5
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• pp.431-440
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• 2015

This study aims to quantify the railway freight performance using various indicators, to compare it over many countries, and to evaluate efficiency of railway freight in Korea. The indicators developed in this study was classified into two categories; country-specific and company-specific indicator. The former includes freight train density, average gross train load and average haul while the latter contains revenue/ton-km, ratio of operating costs to revenue, revenue per employee, ton-km per employee, costs per ton-km and ratio of labor costs to total operating costs. The results of this study shows that Korail performance is in low efficiency due to multi-frequency small amounts transport. The productivity of railway freight in Korea represented as ton-km per employee appears to be lower than that of other oversea companies considered in this study.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.10
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• pp.13-19
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• 2011

This study is to explore the causes for weak signal areas and suggest solutions for the problem of weak signal areas through the experiments for location error of satellite navigation system depending on the characteristics of locations. For kinematic point positioning, a moving object can have different number of satellite navigation systems available depending on its location. It has to receive location data from at least four satellite navigation systems for precise point positioning. However, drastic urbanization and poor surroundings have caused greater location error and weak signal areas. To reduce location error and remove the occurrence of weak signal areas, it is necessary to verify the characteristics of metropolitan surroundings. Therefore, experiments were conducted to measure location error and discover the causes for the occurrence of weak signal areas in metropolitan area, residential area, woods, ocean area, and open ground. In addition, this study suggests a point positioning algorithm with high precision suitable for local surroundings and an algorithm to remove weak signal areas.