• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.120-130
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• 2012

As long span and complex bridges are constructed often recently, safety estimation became a big issue. Various types of measuring instruments are installed in case of long span bridge. New wireless technologies for long span bridges such as sending information through a gateway at the field or sending it through cables by signal processing the sensing data are applied these days. However, The case of occurred accidents related to bridge in the world have been reported that serious accidents occur due to lack of real-time proactive, intelligent action based on recognition accidents. To solve this problem in this study, the idea of "communication among things", which is the basic method of RFID/USN technology, is applied to the bridge monitoring system. A sensor node module for USN based intelligent bridge system in which sensor are utilized on the bridge and communicates interactively to prevent accidents when it captures the alert signals and urgent events, sends RF wireless signal to the nearest traffic signal to block the traffic and prevent massive accidents, is designed and tested by performing TinyOS based middleware design and sensor test free Space trans-receiving distance.

• The KIPS Transactions:PartA
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• v.16A no.2
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• pp.101-112
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• 2009

Existing techniques for defragmentation of the file system need intensive disk operation for some periods at specific time such as disk defragmentation program. In this paper, for solving this problem, we design and implement the automatic and continuous defragmentation free system by distributing the disk operation. We propose the Automatic Layout Scoring(ALS) mechanism for measuring defragmentation degree and suggest the Lazy Copy mechanism that copies the defragmented data at idle time for scattering the disk operation. We search the defragmented file by Automatic Layout Scoring mechanism and then find for empty spaces for that searched file. After lazy copy of searched fils to empty space for preventing that file from being lost, the algorithm solves the defragmentation problem by updating the I-node of that file. We implement these algorithms in Linux and evaluate them for small and defragmented file to get the layout scoring. We outperform the Linux EXT2 file system by $2.4%{\sim}10.4%$ in layout scoring evaluation. And the performance of read and write for various file size is better than the EXT2 by $1%{\sim}8.5%$ for write performance and by $1.2%{\sim}7.5%$ for read performance. We suggest this system for solving the problem of defragmentation automatically without disturbing the I/O task and manual management.

• Journal of the Korean Wood Science and Technology
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• v.40 no.1
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• pp.10-18
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• 2012

A high airtightness is required for the residential spaces constructed recently to save cooling and heating energy through improving insulation performance. Because the chances to release steam formed by human activity in building and inflow of water vapor in outdoor air to residential space are reduced, the natural humidity control performance of interior materials has become more important. In this study, hygroscopic performance of thermo-physically treated wood (Pinus koraiensis) was estimated. At various relative humidity condition, the water vapor adsorption and desorption rates of wooden materials were measured as well as equilibrium moisture content. Effects of roughness and surface microstructure as physical factors and functional groups as chemical factors on the hygroscopicity were analyzed. It is expected that the results from this study and further study of measuring moisture generation in residential spaces could contribute to install a system for evaluating the hygrothermal performance of wooden building.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.1 s.119
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• pp.38-47
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• 2007

This study was carried out to develop a new application field and obtain the basic data of citrus peel as waste in Jeju island and traditional Hanji for producing functional Hanji. The results measuring physical and optical properties, water vapor permeance and antibacterial activity are as follows. It was revealed that apparent density go as down but bulk raise up in the structural view of Hanji with increasing of the addition various Korean citrus peel (citrus unshiu, cheonggyun and hanrabong peel, and citrus unshiu peel powder) percentages, and that the density of Hanji added citrus unshiu peel was higher, but bulk was lower in compared with Hanji added other kinds of peel. Those Hanji added citrus unshiu peel, cheonggyun peel, hanrabong peel and citrus unshiu powder were very great not only in the strength (breaking length, burst index, tear index and folding endurance) but also in water vapor permeant rate in comparison with Hanji. The pHs of Hanji were neutrality (7 to 8). The brightness of the Hanji added various citrus peel percentages was low in compared to Hanji, and the 40% addition of hanrabong peel was the lowest. When 40% hanrabong peel was added to Hanji, it was very yellow in the color degree. When cheonggyun peel was added to Hanji manufacture, water vapor permeant rate was highly effective. It is known that vacant space of intrafiber was reduced by image analysis of Hanji and the additions of peel of citrus unshiu, cheonggyun and hanrabong were distributed equally in the interior of Hanji. The antibacterial activity of Hanji added citrus unshiu peel is more than 98%. After all, it would be able to increase utilization of Hanji, extensively. Namely, production of high quality Hanji added functional materials is expected for new valuable industry of citrus peel and Hanji.

• Tunnel and Underground Space
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• v.22 no.4
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• pp.276-283
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• 2012

Changes in rock properties due to freezing and thawing cycles ranging from $-20^{\circ}C$ to $10^{\circ}C$ were checked for the typical Korean rocks: granite (weathered), limestone, sandstone, tuff, shale and basalt. The porosity, seismic velocity, shore hardness and specific gravity were measured every 10 cycles for each type of rock up to 40 cycles. The specific gravity was rarely changed. Granite (w), shale and basalt decreased gradually in their shore hardness and seismic velocity values, these values for limestone, sandstone and tuff changed only a very little. The porosity increased in the granite (w), shale and basalt, whereas in the others it did not change. Due to the low tensile strength with high porosity, granite (w), shale and basalt were susceptible to the F-T cycles. A linear regression equation was calculated based on the experiment results according to properties and types of rock. The relationship between the freeze-thaw sensitivity (=initial porosity/initial tensile strength) and the coefficients of the regression equation was examined. With additional experimental data, the coefficients of the regression equation can be estimated using the F-T sensitivity. This makes it possible to predict the properties of rock as affected by freeze-thaw weathering by only measuring the initial properties without knowledge of the regression equation coefficients for each type of rock.

• Tunnel and Underground Space
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• v.20 no.2
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• pp.105-111
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• 2010

This study is to consider applicability of spiral bolt strain gauge as an instrument measuring behavior of soft ground foundation and rock slope. When the instrument was installed on the ground, it can be useful to identify the state of ground behavior because it has the characteristics of flexibility, as well as to apply the ground reinforcement because it has higher pull-out resistance to the ground. From the measurement of behavior to soft ground foundation, the strain shows a stable state in the beginning, then was observed significant change in the upper and the middle of spiral bolt strain gauge after 400 days. This is analyzed that ground loosening, which is due to occurred frequent earthquake of magnitude 1~2 with increased rainfall, lead to the instability of the ground. From the measurement of behavior to rock slope, the strain shows a stable state with very little change in a period of 0~50 days and the biggest strain at 4.2 m (P6) in a period of 50~100 days, then other places except P6 was maintained at a stable state in a period of 100~160 days. The reason is analyzed because that blasting for excavated limestone surrounding was affected to the largest at P6. However, based on the size of strain change by behavior of the soft ground foundation and rock slope, it is considered that the present condition are not effected on stability of retaining structure and rock slope. In conclusion, the proposed spiral bolt strain gauge can be useful to measure behavior of soft ground foundation and rock slope, and also to be measured behavior as well as reinforcement of the target ground.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.709-718
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• 2016

The study considers viewpoints for qualitative improvement of landscape planning based on research literature, books and reports. By classifying items used in this study, evaluation criteria was derived for viewpoint selection using SPSS Statistics. In addition, we establish weights and prioritize viewpoints by measuring the relative importance within the hierarchical index. The analysis results are as follows: First, 16 viewpoints were determined using surveys from experts to establish specific and systematic plans for landscape simulation. Second, with respect to the medium classification level of viewpoint evaluation, the most important factor found was 'view' followed by 'publicness' and 'place.' Third, priority by viewpoint was found to exhibit the following order of relative importance: visual openness of viewpoint, favorability as view target, cultural property space, historicity, public place, gateway place, area where the target can be observed, thickly-populated or most-used place, place where various shapes of targets and surrounding landscape can be identified, ecological protection area, river and waterside area, viewing angle (relief-etching), viewing direction, major roads, distance between the viewpoint and the target, and plains and farmland. These results can contribute to developing systematic and reliable analysis frame for qualitative improvement of landscape planning and evaluating landscape simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.50-57
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• 2017

In the injection molding process, a core that builds a space for a product is installed at the internal place in the mold and fabricated as the frame of the mold. In this make up, the fabricating partial form of the mold at a pin is a core pin. The core pin is finer because an injection mold produces miniaturization and integration. On the other hand, when the core is manufactured using the existing centerless grinder, it generates vibrations because of the lack of a fixed zig for a micro size workpiece. For this reason, an existing centerless grinder without a micron size fixed zig, makes a defective product due to vibration and deformation. In this study, a compact grinding system that can be installed using an existing centerless grinder was fabricated to make a micro size core pin. Using the compact grinding system, grinding experiment for core pin was carried out. The performance of the system was confirmed by measuring the surface roughness, roundness, and cylindricity.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.943-948
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• 2021

The purpose of this study was to investigate changes in surface dose due to increased scattering of gamma rays from patients injected with ^99mTc and ¹⁸F, which are radioactive isotopes, in close contact with materials with high atomic number such as the walls of the stable room. Prepare ^99mTc and ¹⁸F by injecting 20 and 10 mCi respectively into the NEMA phantom, and then measuring the surface dose for 60 minutes by positioning the phantom at a height of 1 m above the surface, at a distance of 0, 5 and 10 cm from the wall, and at the same location as the phantom facing the wall. Each experiment was repeated five times for reproducibility of the experiment and one way analysis of variability (ANOVA) was performed for significance testing and Tukey was used as a post-test. The study found that surface doses of 220.268, 287.121, 243.957, and 226.272 mGy were measured at ^99mTc, respectively, in the case of empty space and in the case of 0, 5 and 10 cm, while those of ¹⁸F were measured at 637.111, 724.469, 657.107, and 640.365 mGy, respectively. In order to reduce changes in surface dose depending on the patient's location while waiting, it is necessary to keep the distance from the ground or the wall where the patient is closely adhered to, or install an air mattress, etc., to prevent the scattered lines as much as possible, considering the scattered lines due to the wall etc. in future setup of the patient waiting room and safety room, and in addition to the examination, the external skin width may be reduced.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.4
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• pp.217-233
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• 2020

This study evaluated the urban vitality of Daegu metropolitan city in 2018 using emerging geographic data such as spatial big data, Wi-Fi AP(access points) and nighttime light satellite image. The emerging geographic data were used in this research to quantify human activities in the city more directly at various spatial and temporal scales. Three spatial big data such as mobile phone data, credit card data and public transport smart card data were employed to reflect social, economic and mobility aspects of urban vitality while public Wi-Fi AP and nighttime light satellite image were included to consider virtual and physical aspects of the urban vitality. With PCA (Principal Component Analysis), five indicators were integrated and transformed to the urban vitality index at census output area by temporal slots. Results show that five clusters with high urban vitality were identified around downtown Daegu, Daegu bank intersection and Beomeo intersection, Seongseo, Dongdaegu station and Chilgok 3 district. Further, the results unveil that the urban vitality index was varied over the same urban space by temporal slots. This study provides the possibility for the integrated use of spatial big data, Wi-Fi AP and nighttime light satellite image as proxy for measuring urban vitality.