• Composites Research
• /
• v.32 no.6
• /
• pp.395-402
• /
• 2019

The RFI process is an OoA process that fiber mats and resin films are laminated and cured in a vacuum bag. In case that resin film is insufficient to fill empty space in fibers, it makes void defect in composites and this void decrease mechanical properties of the composites. For this reason, non-destructive testing is usually used to evaluate void of manufactured composites. So, in this study, a manufacturing method of standard void specimens, which are able to be used as references in non-destructive testing, was proposed by controlling resin film thickness in the RFI process. Also, a fiber compaction test was proposed as a method to set the resin film thicknesses depending on target voids of manufacturing panels. The target void panels of 0%, 2%, and 4% were made by the proposed methods, and signal attenuation depending on void was measured by non-destructive testing and image analysis. In addition, voids of specimens for tensile, in-plane, short beam and compressive tests were estimated by signal attenuation, and mechanical properties were evaluated depending on the voids.

• Korean Journal of Poultry Science
• /
• v.34 no.3
• /
• pp.165-172
• /
• 2007

We investigated the effects of dietary supplements of probiotics, illite, active carbon and hardwood vinegar on growth performance, feed intake, and pH, shear force, sensory evaluation, meat color and fatty acid composition of meat in broilers. Two hundred broilers were fed diets for five weeks containing 0.2% of probiotics (T1), and 1% of Illite (T2), 1% active carbon (T3), or 1% hardwood vinegar (T4). Body weight gain was higher in T1 and T4 groups fed the starter diet but was the lowest in C and T4 for finishing period (P<0.05). Feed efficiency was not significantly different. In proximate composition, crude fat content of chicken meat were decreased lower in all treatment groups than control, but moisture, crude protein and crude ash were not significantly different. Cooking loss was decreased in T3 and T4 and WHC (water holing capacity) was increased in T3 and T4 groups compared to the other groups. In sensory evaluation, T4 tended to improve the hardness. Redness $(a^*)$ and yellowness $(b^*)$ were no difference between the all treatment groups, lightness $(L^*)$ were higher in T1, T2, T3 and T4 groups than control group (P<0.05). Stearic acid content was lower in T1, T2, T3 and T4 groups, but oleic acid contents were higher in T1, T2, T3 and T4 groups (P<0.05). These results showed that supplementing broiler diets with 1.0% hardwood vinegar may noticeably improve the meat quality of broiler.

• The Journal of Engineering Geology
• /
• v.17 no.2 s.52
• /
• pp.205-215
• /
• 2007

In this study, the soil characteristics are analyzed using the result of various soil tests as an object of the soil layer of natural slopes in landslides areas. Also, the relationship with landslides and interrelation with each soil properties are analyzed. The landslides in three areas with different geological condition are occurred due to heavy rainfall in same time. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. However soil characteristics have a little differentiation to geological condition, the soils sampled from landslide area have higher proportion of fine particle and porosity, and lower density than those from non landslide area. In case of same geological condition, landslides are occurred in the terrain slope with high permeability. The permeability is mainly influenced by the soil characteristics such as particle size distribution, porosity, particle structure, and the geological origins such as weathering, sedimentary environment. The soil layer with high internal friction angle is more stable than that with low internal friction angle in all geological condition. The permeability is mainly influenced by effective particle size, coefficient of uniformity, coefficient of gradation, porosity, density and so on. Also, those have interrelation with each factor. These interrelations are similar in all study area. Meanwhile, in proportion as the void ratio and the porosity rises the permeability increases.

• Korean Journal of Poultry Science
• /
• v.41 no.4
• /
• pp.271-277
• /
• 2014

The objective of this study was to determine the effect of the meat from spent laying hen on the shelf-life and physicochemical properties of emulsified sausage. Four types of sausage were made: 0% (Control), 10% (T1), 20% (T2) and 30% (T3) of spent hen meat added. Each sausage type was tested in triplicate. The addition of spent hen meat resulted in decreased crude fat and cooking loss, and increased WHC (water holding capacity), CIE $a^*$ and hardness. Values for crude fat and cooking loss were significantly decreased by the addition of spent laying hen meat relative to the control (P<0.05). Especially, T3 was significantly (P<0.05) decreased compare to other treatment groups. Spent laying hen meat addition had no significantly effects on moisture, crude protein, crude ash, pH, WHC, TBARS (thiobarbituric acid reactive substance) values, shear force, total plate counts (TPC), CIE $L^*$ and $b^*$ values. In conclusion, this study demonstrates that the addition of spent laying hen meat to emulsified sausages tended to improve sausage quality.

• Food Science of Animal Resources
• /
• v.30 no.5
• /
• pp.860-866
• /
• 2010

This study was conducted to investigate the effects of dietary supplementation of garlic by-products on TBARS, WHC (water holding capacity), shear force, pH, total phenol content, DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity, meat color, sensory evaluation, and fatty acid composition of chicken meat. Broiler chicks were fed for 5 wk with experimental diets of 0% garlic by-product (Control), 1% garlic by-product (T1), 2% garlic by-product (T2), and 5% garlic by-product (T3). TBARS and pH were significantly decreased by the supplementation of garlic by-products compared to the control (p<0.05). Compared to the control diet, the total phenol content and DPPH radical scavenging activity were significantly increased by the supplementation of garlic by-products (p<0.05). The total phenol content and DPPH radical scavenging activity of treatment groups were higher than the control; in particular, T3 was significantly (p<0.05) more effective in improving freshness compared to other treatment groups. CIE $a^*$ value of treatment groups (especially T3) showed significantly higher values compared to the control; however, no difference in the CIE $L^*$ and $b^*$ values were observed among treatments. In its fatty acid composition, amounts of linoleic acid and linolenic acid in chicken meat was increased by the supplementation of garlic by-products, but amounts palmitic acid were decreased. In conclusion, supplementation with garlic by-products was effective in decreasing TBARS, pH, and saturated fatty acids, and in increasing total phenol content, DPPH radical scavenging activity, and unsaturated fatty acids.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.8
• /
• pp.103-111
• /
• 2004

There are some problems in evaluating the bearing capacity of decomposed granite soils by general equations on account of their inherent compressibility and crushability. In order to investigate this kind of the engineering characteristics on decomposed granite soils in detail, it is necessary to how the micro property of the single particle composing the granite soils, and then the relevance to the macro characteristics of the soils has to be cleared. The reason why the single particle properties are not studied is first the difficulty to find out some regulating parameters, and secondly little understanding of its significance. Furthermore, the water in the decomposed granite soils accelerates the particle crushing. Consequently, increasing of compressibility and decreasing of shear strength would occur. Actually, when the ground settlement is a big issue in the embanked ground using the decomposed granite soils, the sensitive change of compressibility due to the change of water content in the ground becomes conspicuous. In this study, the single particle strength characteristics are studied and microscopic particle shape analyses are performed. In addition the compressibility of the decomposed granite soils and water content effect on the compressibility are analysed based on the test results.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.4
• /
• pp.35-46
• /
• 2017

Most of high carbon fly ashes (HCFA) are discarded in landfills with high costs due to low recycling rate. This study aims to explore the geotechnical behaviors of HCFA mixtures reinforced with fiber and sand. A series of compaction test, unconfined compressive strength test and modified 1D consolidation test with bender element were performed. Specimens were prepared at their optimal moisture contents based on the results of compaction tests. The results of this study demonstrate that the inclusion of fibers to the matrix of HCFA increases unconfined compressive strength (UCS), strain at UCS, and maximum shear modulus ($G_{max}$) at a given void ratio. Reinforcement with sand increases UCS of HCFA; while the strain at UCS is irrelevant with sand fractions. Sand particles may disrupt the direct contacts between HCFA particles at low sand content, resulting in a decrease in $G_{max}$. However, it can be expected that the mixtures with sand content larger than 20% are in dense state; thus, $G_{max}$ of HCFA reinforced with sand shows greater value than that of unreinforced HCFA compacted with the same energy. Regardless of types of reinforcement, the compression index ($C_c$) of both fiber and sand reinforced HCFA is mainly determined by initial void ratio.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.8
• /
• pp.5-14
• /
• 2010

Recent researches on the behavior of gravelly soils have been focused mainly on the relative density or on the gravel content. And some researchers presented the liquefaction behavior based on the relative density whereas others based on the gravel content of gravelly soil. However the relative densities vary with gravel content and relative density is not enough to fully express the behavior of gravelly soils. Therefore in this research state parameter which considers void ratio and effective confining pressure is introduced and Steady State Line(SSL) of gravelly soils for various gravel content are determined by undrained triaxial tests in order to express the behavior of gravelly soils. From the research the position of SSL moved downward with gravel content. And the same density of soil showed dense sand behavior or loose sand behavior depending upon the confining pressure. Especially relative density 80% of gravelly soil showed loose sand behavior under high confining pressure. However the gravelly soils with similar state parameters showed similar stress behaviors. It can bee seen that state parameter is useful tool to evaluate undrained behavior of gravelly soils. Also state parameter and undrained strength showed good correlations.

• Journal of the Korean Geosynthetics Society
• /
• v.10 no.4
• /
• pp.71-79
• /
• 2011

In this study, the variation of wetting front and ground water level at the embankment constructed in the Saemangeum area were predicted considering rainfall duration times and the slope stability analysis of the embankment was carried out according to prediction results of wetting front and ground water level. The embankment was formed by dredging soils. A suction stress, a cohesion and a frictional angle of dreding soils measured by soil tests were applied to estimate the unsaturated soil properties. According to the analysis results of the wetting front and the ground water level for various rainfall duration time, the wetting front began to descend from the upper part of embankment at the beginning time of rainfall and after 1 hour of rainfall duration time. After that, the ground water level continued to ascend as the rainfall duration time was getting longer. After rainfall, the ground water level was distributed at a certain depth, and the ground water level was gradually descending as time goes by. According to the slope stability analysis of the embankment considering the variation of the wetting front and the ground water level, the safety factor of slope was rapidly reduced as the rainfall began to infiltrate into the ground, and the minimum safety factor of slope was estimated after 24 hours of rainfall duration time. Meanwhile, the safety factor of slope was increased with regaining the matric suction in the ground after rainfall.

• Journal of the Korean Geosynthetics Society
• /
• v.8 no.2
• /
• pp.47-54
• /
• 2009

The ballast track, the most common type of conventional railroad track in Korea, is deteriorated by abrasion of ballast, it's penetration into roadbed, and rugged surface of roadbed caused by cyclic loading of train. Persistent occurrence of those phenomena lead to insufficient drain capacity, one of major factors in track design, and it increases pore water pressure and decreases of shear strength under rainfall condition leading to unstable roadbed. In this study, cylindrical model tests are executed for 3 types of geotextile applying cyclic loading in order to observe the characteristics of displacement and bearing capacity of geotextile, and undrained condition has been applied for 0 day, 3 days and 7 days to each geotextiles. The results showed that there was about 1% difference at the final displacement rates between reinforced soils and nature soils and the displacement of the ground surface increases along with the degrees of the saturation. And in case that water contents exceeds the threshold, it is also apparent that weight and tensile strength of geotextile influences displacement of the ground surface. And the larger weight of geotextile is, the smaller plastic displacement. It is evaluated that non-woven fabric comes into effect on reducing the bearing capacity but, the weight of geotextile has little influence on it.