• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.1
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• pp.48-57
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• 2015

In a sodium-cooled fast reactor, which is a Generation-IV reactor, refueling is conducted by rotating, but not opening, the reactor head to prevent a reaction between the sodium, water and air. Therefore, an inspection technique that checks for the presence of any obstacles between the reactor core and the upper internal structure, which could disturb the rotation of the reactor head, is essential prior to the refueling of a sodium-cooled fast reactor. To this end, an ultrasound-based inspection technique should be employed because the opacity of the sodium prevents conventional optical inspection techniques from being applied to the monitoring of obstacles. In this study, a ranging inspection technique using a plate-type ultrasonic waveguide sensor was developed to monitor the presence of any obstacles between the reactor core and the upper internal structure in the opaque sodium. Because the waveguide sensor installs an ultrasonic transducer in a relatively cold region and transmits the ultrasonic waves into the hot radioactive liquid sodium through a long waveguide, it offers better reliability and is less susceptible to thermal or radiation damage. A 10 m horizontal beam waveguide sensor capable of radiating an ultrasonic wave horizontally was developed, and beam profile measurements and basic experiments were carried out to investigate the characteristics of the developed sensor. The beam width and propagation distance of the ultrasonic wave radiated from the sensor were assessed based on the experimental results. Finally, a feasibility test using cylindrical targets (corresponding to the shape of possible obstacles) was also conducted to evaluate the applicability of the developed ranging inspection technique to actual applications.

• Geotechnical Engineering
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• v.12 no.4
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• pp.157-178
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• 1996

Current design methods for reinforced earth structures take no account of the magnitude of the strains induced in the tensile members as these are invariably manufactured from high modulus materials, such as steel, where straits are unlikely to be significant. With fabrics, however, large strains may frequently be induced and it is important to determine these to enable the stability of the structure to be assessed. In the present paper internal design method of analysis relating to the use of fabric reinforcements in reinforced earth structures for both stress and strain considerations is presented. For the internal stability analysis against rupture and pullout of the fabric reinforcements, a strain compatibility analysis procedure that considers the effects of reinforcement stiffness, relative movement between the soil and reinforcements, and compaction-induced stresses as studied by Ehrlich 8l Mitchell is used. I Bowever, the soil-reinforcement interaction is modeled by relating nonlinear elastic soil behavior to nonlinear response of the reinforcement. The soil constitutive model used is a modified vertsion of the hyperbolic soil model and compaction stress model proposed by Duncan et at., and iterative step-loading approach is used to take nonlinear soil behavior into consideration. The effects of seepage pressures are also dealt with in the proposed method of analy For purposes of assessing the strain behavior oi the fabric reinforcements, nonlinear model of hyperbolic form describing the load-extension relation of fabrics is employed. A procedure for specifying the strength characteristics of paraweb polyester fibre multicord, needle punched non-woven geotHxtile and knitted polyester geogrid is also described which may provide a more convenient procedure for incorporating the fablic properties into the prediction of fabric deformations. An attempt to define improvement in bond-linkage at the interconnecting nodes of the fabric reinforced earth stracture due to the confining stress is further made. The proposed method of analysis has been applied to estimate the maximum tensions, deformations and strains of the fabric reinforcements. The results are then compared with those of finite element analysis and experimental tests, and show in general good agreements indicating the effectiveness of the proposed method of analysis. Analytical parametric studies are also carried out to investigate the effects of relative soil-fabric reinforcement stiffness, locked-in stresses, compaction load and seepage pressures on the magnitude and variation of the fabric deformations.

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.63-74
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• 2006

During the construction of circular underground pipe, the non-proper compaction along the pipe and the decrease of compaction efficiency have been the main problems to induce the failure of underground pipe or facility. The use of CLSM (controlled low strength materials) should be one of the possible applications to overcome those problems. In this research, the full-scaled field test and the numeric analysis using PENTAGON-3D FEM program were carried out for three different cases on the change of backfill materials, including the common sand, the soil from construction site, and the CLSM. From the full-scaled test in field, the use of in-situ CLSM as backfill materials reduced the vertical and lateral deformation of the pipe, as well as the deformation of the ground surface. The main reason for reducing the deformation would be the characteristics of the CLSM, especially self-leveling and self-hardening properties. The measured earth pressure at the surround of the corrugated pipe using the CLSM backfills was the smaller than the other cases, and the absolute value was almost zero. Judging from the full-scaled field test and FEM analysis, the use of CLSM as backfill materials should be one of the best choices reducing the failure of the underground pipes.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.6
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• pp.834-839
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• 2007

This study was designed to determine the optimal ratio of dropwort powder in castella by adding the powder at levels of 0, 3, 6, 9, and 12% respectively. The properties of the castella were analyzed by specific gravity, specific volume, color determinations, texture properties and sensory evaluation. The Specific gravity increased with increasing amount of dropwort powder. However, the specific volume decreased with increasing dropwort powder. For the color values, as more dropwort powder was added, the L-value decreased. The castella with 9% dropwort powder had a higher hardness, gumminess, and chewiness. A sensory panel perceived that the external and internal color of the castella become darker with the dropwort powder substitution and the grain size decreased with increasing amount dropwort powder, while sweet taste showed no significant difference. The order of overall preference was DP 9>DP 6>DP 12>CON>DP 3. Therefore, the substitution of 9% of wheat flour with dropwort powder was recommended in the production of castella.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.83-91
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• 2019

The purpose of this study is to assess a fire-damaged concrete structure using a digital camera and image processing software. To simulate it, mortar and paste samples of W/C=0.5(general strength) and 0.3(high strength) were put into an electric furnace and simulated from $100^{\circ}C$ to $1000^{\circ}C$. Here, the paste was processed into a powder to measure CIELAB chromaticity, and the samples were taken with a digital camera. The RGB chromaticity was measured by color intensity analyzer software. As a result, the residual compressive strength of W/C=0.5 and 0.3 was 87.2 % and 86.7 % at the heating temperature of $400^{\circ}C$. However there was a sudden decrease in strength at the temperature above $500^{\circ}C$, while the residual compressive strength of W/C=0.5 and 0.3 was 55.2 % and 51.9 % of residual strength. At the temperature $700^{\circ}C$ or higher, W/C=0.5 and W/C=0.3 show 26.3% and 27.8% of residual strength, so that the durability of the structure could not be secured. The results of $L^*a^*b$ color analysis show that $b^*$ increases rapidly after $700^{\circ}C$. It is analyzed that the intensity of yellow becomes strong after $700^{\circ}C$. Further, the RGB analysis found that the histogram kurtosis and frequency of Red and Green increases after $700^{\circ}C$. It is analyzed that number of Red and Green pixels are increased. Therefore, it is deemed possible to estimate the degree of damage by checking the change in yellow($b^*$ or R+G) when analyzing the chromaticity of the fire-damaged concrete structures.

• Journal of Life Science
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• v.23 no.9
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• pp.1079-1087
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• 2013

Speed germination success and robust vegetative growth of citrus rootstock through improved sowing methods and fertilizer inputs offer the usage of root system for the citrus. The current study evaluated the influence of seed coat removal and different fertilizer concentrations on plant germination and plant growth of spontaneous rootstock siblings. Decoated and coated seeds of diploid and tetraploid plants were sown in tubes. Commercial fertilizer concentrations of 0, 2, 4, 6, 8 and $10g{\cdot}l^{-1}$ were added. The experimental layout followed a randomized block $2{\times}6$ factorial design (seed coat removal ${\times}$ fertilizer concentration) for each rootstock. Fertilizer concentrations were 0, 10, 20 and $30g{\cdot}l^{-1}$ of the fertilizer for the resistance of the strength on the salt level. The germination rate of seeds without testa sown in vitro was improved (67-80%) compared to that of nontreated seeds. The eventual tree height of the seeds without testa in the diploid group was increased due to higher fertilization compared to that in the nontreated group. The removal of seed testa promoted the seed germination of both diploid and tetraploid trifoliate orange and resulted in greater height. Their vegetative development was also increased due to the increased fertilization of the rootstock. The Fv/Fm value for the diploid plants was 0.4 and 0.8 for the tetraploid ones under salt stress after 11 days of treatment. The removal of seed testa may improve the seed germination of trifoliate orange. Tetraploid trifoliate orange appears to possess resistance to salt stress compared to the diploid variety.

• Economic and Environmental Geology
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• v.36 no.2
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• pp.89-101
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• 2003

River deposits and farmland soils were analyzed to investigate the pollution level of heavy metals in the vicinity of the Goro abandoned Zn-mine. Surface (0-40 cm) and subsurface (40-100 cm) soils were collected around a main river located at the lower part of the Goro mine, and analyzed by ICP-MS for Cd, Cu, Pb, Zn and Cr after 0. 1N HCI extraction and by AAS for As after IN HCI extraction. Concentrations of cadmium and lead at the surface river deposits close to the mine were over the Soil Pollution Warning Limit (SPWL), and 43% of sample sites (6 of 14 samples) were over SPWL for As suggesting that river deposits were broadly contaminated by arsenic. Results from farmland soil analysis showed that surface soils were contaminated by heavy metals, while only arsenic was over SPWL at 50% of sampling sites. Main pollution mechanism around the Goro mine was the discharge of mine tailing and waste rocks from the storage site to the river and to adjacent farmland during flood season. Pollution Grades for sample locations were prescribed by the Law of Soil Environmental Preservation, suggesting that the pollution level of heavy metals around the Goro mine was serious, and the remediation operation fur arsenic and the isolation of mine tailing and waste rocks from river and farmland should be activated to protect further contamination. The area needed to clean up was estimated from pollution distribution data and the remediation methods such as a soil washing method and a soil improvement method were considered as the further remediation operation for arsenic contaminated soils and river deposits around the Goro abandoned mine.

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.1-7
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• 2004

Roads, like bikeways, parkways and walks, are to be just capable of supporting light traffic and traveling public, but they are required to be human friendly and environmental-oriented. Lately soil-solidifier mixture, a kind of soil-cement, has developed and has been applied to the recycling and environment-oriented pavement as the surfacing material. Soil-solidifier pavement structure has been designed by only experience. To design this pavement mechanically, it is necessary to find out basic engineering properties of soil-solidifier mixture. This study focuses on finding out mechanical characteristics of the mixture according to mixture proportions and aging. Test molds with various mixture proportions are made, and then unconfined strength tests are performed for test molds with aging of the mixture. As the result of this study, it is found that the strength of the mixture increases with amount of cement and that maximum strength is achieved at 6%$\sim$8% of the ratio of solidifier and water. The strength increase rapidly until 14 days, after then slowly. After 28 days the strength of the mixture approaches to the constant value. The heat of hydration during curing of the mixture is measured no significantly. It also shows that temperature characteristics of the mixture is similar to that of soil. Since this mixture is mixed with soil and is able to improve engineering problems in pavement due to temperature, this mixture is expected to use effectively in the environment-oriented pavement for light traffic.

• Korean Journal of Agricultural Science
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• v.34 no.1
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• pp.53-60
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• 2007

A layer feeding trial was conducted for 10 weeks to investigate the effects of the addition of corn distillers dried grains with solubles (DDGS) to layer diets on the laying performance, egg qualities, and yolk fatty acid composition. Nine hundred Hyline Brown layers, 24 weeks of age,were randomly allotted to 20 replicate laying cages, 45 birds per replicate. There were four diet treatments (0, 10, 15, and 20% DDGS), and five replicates per treatment. All experimental diets were prepared to contain iso-protein (17%) and iso-calorie (TMEn 2,780 kcal/kg). The use of DDGS up to 20% level in layer diets did not exert any influence on feed intake, laying rate, total egg mass, mean egg weight, and feed conversion ratio. DDGS did not exert any influence in weight of egg, breaking strength, and color of eggshell. The albumen height and Haugh unit was not influenced by DDGS addition. The yolk color was significantly increased by DDGS supplementation. As the DDGS level increased, the oleic acid content decreased, and the linoleic acid increased (P<0.05). The degree of saturation of yolk fatty acids was not affected by dietary DDGS. The inclusion of DDGS up to 20% in layer diets resulted in the decrease of feed cost per kg without any effect in the laying performance. In conclusion, the use of DDGS up to 20% level in layer diets could replace corn and soybean meal without any harmful effect on the laying performances.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.33-38
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• 2021

Recently, rollable and foldable displays are attracting great attention in the flexible display market due to their excellent form factor. To predict and prevent the mechanical failure of the display panels, it is essential to accurately understand the mechanical properties of brittle SiN_x thin films, which have been used as an insulating film in flexible displays. In this study, tensile properties of the ~130 nm- and ~320 nm-thick SiN_x thin films were successfully measured by coating a ~190 nm-thick organic nano-support-layer (PMMA, PS, P3HT) on the fragile SiN_x thin films and stretching the films as a bilayer state. Young's modulus values of the ~130 nm and ~320 nm SiN_x thin films fabricated through the controlled chamber pressure and deposition power (A: 1250 mTorr, 450 W/B: 1000 mTorr, 600 W/C: 750 mTorr, 700 W) were calculated as A: 76.6±3.5, B: 85.8±4.6, C: 117.4±6.5 GPa and A: 100.1±12.9, B: 117.9±9.7, C: 159.6 GPa, respectively. As a result, Young's modulus of ~320 nm SiN_x thin films fabricated through the same deposition condition increased compared to the ~130 nm SiN_x thin films. The tensile testing method using the organic nano-support-layer was effective in the precise measurement of the mechanical properties of the brittle thin films. The method developed in this study can contribute to the robust design of the rollable and foldable displays by enabling quantitative measurement of mechanical properties of fragile thin films for flexible displays.