• Food Science of Animal Resources
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• v.38 no.5
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• pp.959-969
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• 2018

This study investigated the effects of deep freezing and storage temperature ($-50^{\circ}C$, $-60^{\circ}C$, and $-80^{\circ}C$) on the quality and freshness of lamb. To compare the qualities of deep frozen and stored lamb, fresh control and normal freezing conditions ($-18^{\circ}C$) were adopted. As quality and freshness parameters, drip loss (thawing loss and cooking loss), water-holding capacity (WHC), texture profile analysis (TPA), thiobarbituric acid reactive substances (TBARS), and total volatile basic nitrogen (TVBN) were evaluated during 5 months of storage. Temperature influenced the drip loss and WHC, and deep freezing minimized the moisture loss during frozen storage compared to the normal freezing condition. Lamb frozen and stored at deep freezing temperature showed better tenderness than that stored in normal freezing conditions. In particular, lamb frozen at lower than $-60^{\circ}C$ exhibited fresh lamb-like tenderness. Regardless of temperature, evidence of lipid oxidation was not found in any frozen lamb after 5 months, while TVBN was dependent on the applied temperature. Therefore, this study demonstrated that deep freezing could potentially be used to maintain freshness of lamb for 5 months. From the quality and economic aspects, the freezing and storage condition of $-60^{\circ}C$ is estimated as the optimum condition for frozen lamb.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.5-17
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• 2012

The amount of snow due to global warming and climate change has recently increased. The effective management of snow removal materials will be required. First, on the basis of domestic winter temperature, it is not necessary to get a baseline to less than the freezing point of $-52^{\circ}C$ for the calcium chloride($CaCl_2$) of 30%.. In terms of cost comparison between calcium chloride($CaCl_2$) and sodium chloride($NaCl$), the calcium chloride($CaCl_2$) is 2 to 3 times more expensive, and the supply of the calcium chloride($CaCl_2$) is not produced in domestic country and is in the conditions that have to imports all needed. Accordingly, the effective use scheme of snow removal materials should be considered to multifaceted ways. Thus, the objective of this study is to develop effective method and to replace from calcium choride($CaCl_2$) to sodium chloride($NaCl$) solution in the current snow removal operating system that uses a pre-wetted salt spreading method. The effective method that equals to the quality of the existing snow removal materials was developed in this study through performance tests for deicing chemicals, corrosion test of steel and freezing and thawing tests of concrete.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.197-208
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• 2003

This paper is to determine the possibility of re-using waste concrete from Incheon city area. The strength test was conducted with five aggregate compounds which was replaced a natural aggregate with recycled aggregate. After checking the physical characteristics of recycled aggregate compounds, the mix design of recycled concrete was conducted. For the relatively comparison between natural and recycled compounds, while the unit aggregate weight was changed, other conditions were fixed. The freezing and thawing test which included fly-ash and super-plastezer were performed to check the durability and workability when recycling waste concrete. In the physical characteristics of recycled aggregate, it was found that the specific gravity of recycled coarse aggregate and recycled fine aggregate satisfied the first grade of recycle specification(KS), and all compounds of recycled aggregate also satisfied the second grade of absorption specification, Especially up to the 50% substitution of recycled aggregate is equal to or a bit lower than that of convention aggregate. In comparison with conventional concrete, the recycled concrete is lower than maximum by 7% in compressive strength decreasing rate after freezing-thawing test. From now, although most of recycled concrete was used to the building lot, subgrade, asphalt admixture, through the result. It was proved that possibility of re-using recycled aggregate as the substructure of bridge, retaining wall, tunnel lining and concrete structure which is not attacked the drying shrinkage severely.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.641-649
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• 2015

The purpose of this study was to assess the durability of high-strength concrete with high volume mineral admixture (HVMAC) derived from previous studies within ternary blended concrete (TBC) and normal concrete (NC). Four durability evaluation types such as chloride penetration resistance, freezing and thawing resistance, carbonation resistance in two pre-treatment conditions, and sulfuric acid and sulfate resistance using 5% sulfuric acid ($H_2SO_4$), 10% sodium sulfate ($Na_2SO_4$), and 10% magnesium sulfate ($MgSO_4$) solution were selected and performed in this study. HVMAC showed the excellent chloride penetration resistance in any age and the freezing and thawing durability close to 100%. In addition, HVMAC affected more reduction in carbonation resistance than TBC. When the curing time was increased, to create a concrete internal organization densely improved resistance to carbonation. HVMAC also showed the most superior in sulfuric acid and sulfate resistance. As the reduction of calcium hydroxide and $C_3A$ to apply a large amount of admixture reduced the swelling and cracking of concrete, the strength reduction and mass change of concrete was found to be small indicated.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.17-25
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• 2014

In the present study, it were performed an unconfined compression test and a field applicability test according to a mixed ratio of SS, soil type and curing period to analyze strength and deformation characteristic in order to evaluate engineering characteristics of soil mixed pavements using the eco-friendly soil stabilizer (SS). The test results revealed that SS mixed soil shows fast strength development at the initial curing time while 28-day strength amounted for 97% of the final strength. Furthermore, coarse-grained dredged sand (DS) and weathered granitic soil (WGS) have a larger ratio of deformation coefficient with respect to unconfined compressive strength than fine-grained dredged clay (DC) and organic soil (OS). Moreover, a comparison test between natural and forced drying conditions was conducted and test result showed 54% to 67% of strength degradation while having 55% to 63% of strength degradation in the freezing and thawing test result. Finally, a repeated loading test result showed that DS experiences up to 35% of strength reduction compared to initial strength under 10,000 times loading in maximum. Thus, it was validated that an appropriate amount of fine-grained sand is necessary to secure resistance capability to repeated loading.

• Journal of the Korean GEO-environmental Society
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• v.14 no.7
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• pp.19-29
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• 2013

Analysis via classical soil mechanics theory is either ineffective or inappropriate for fully describing stress distribution or failure conditions in cold regions, since mechanical properties of soils in cold regions are different from those reported in the classical soil mechanics theory. Therefore, collecting and analyzing technical data, and systematic and specialized research for cold regions are required for design and construction of the structure in cold regions. Freezing and thawing repeat in active layer of permafrost region, and a loading condition affecting the structure changes. Therefore, the reliable analysis of mechanical properties of frozen soils according to various conditions is prerequisite for design and construction of the structure in cold regions, since mechanical properties of frozen soils are sensitive to temperature condition, water content, grain size, relative density, and loading rate. In this research, the direct shear apparatus which operates at 30 degrees below zero and large-scaled low temperature chamber are used for evaluating shear strength characteristics of frozen soils. Weathered granite soil is used to analyzed the shear strength characteristics with varying freezing temperature condition, vertical confining pressure, relative density, and water content. This research shows that the shear strength of weathered granite soil is sensitively affected by various conditions such as freezing temperature conditions, normal stresses, relative densities, and water contents.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.299-306
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• 2016

In this research, influence of low quality aggregate on engineering properties of concrete was evaluated experimentally. From the experiment, the fresh properties of slump and air content were controlled with unit water and AE dosage and all mixture were designed to have similar fresh properties of slump and air content with various quality of aggregate. Under this conditions, comparing with the mixture with high quality aggregate, the mixture with low quality aggregate showed the unit water and AE dosage were increased about 18 and 98%, respectively, because of poor grading and quantity of fines. For compressive strength, the low quality aggregate, specifically, exploded debris, clay sand, and sea sand contributed on decreasing compressive strength about 20~35%. Additionally, the concrete mixture including low quality fine and coarse aggregate showed adverse quality in not only compressive strength but also durability of freeze-thawing resistance, drying shrinkage, carbonation, and chloride ingression. Therefore, it is considered that for low quality aggregate, extra treatment processes such as washing or controlling gradation, and regulation to limit the use of low quality aggregate are needed.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.12
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• pp.1773-1782
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• 2014

The aim of the experiment was to study the effect of feeding system on meat quality characteristics of Small East African (SEA) goats and their crosses with Norwegian ($SEA{\times}N$) goats finished under small scale farming conditions. Twenty four castrated goats at the age of 18 months with live body weight of $16.7{\pm}0.54kg$ from each breed (SEA and $SEA{\times}N$) were distributed in a completely randomized design in a $2{\times}3$ factorial arrangement (two breed, and three dietary treatments). The dietary treatments were; no access to concentrate (T0), 66% access to ad libitum concentrate allowance (T66) and 100% access to ad libitum concentrate allowance with 20% refusal (T100) and the experimental period was for 84 days. In addition, all goats were allowed to graze for 2 hours daily and later fed grass hay on ad libitum basis. Daily feed intakes were recorded for all 84-days of experiment after which the animals were slaughtered. Feed intake of T100 animals was 536 g/d, which was 183 g/d higher than that of T66 group. Supplemented goats had significantly (p<0.05) better feed conversion efficiency. The SEA had higher (p<0.05) hot carcass weight (8.2 vs 7.9 kg), true dressing percentage (54.5 vs 53.3) and commercial dressing percentage (43.3 vs 41.6) compared to $SEA{\times}N$. There was no significant difference (p>0.05) for dressing percentage and carcass conformation among supplemented goats except fatness score, total fat depots and carcass fat which increased (p<0.05) with increasing concentrate levels in the diet. Increasing level of concentrate on offer increased meat dry matter with subsequent increase of fat in the meat. Muscle pH of goats fed concentrate declined rapidly and reached below 6 at 6 h post-mortem but temperature remained at $28^{\circ}C$. Cooking loss and meat tenderness improved (p<0.05) and thawing loss increased (p<0.05) with ageing period. Similarly, meat tenderness improved (p<0.05) with concentrate supplementation. Shear force of muscles varied from 36 to 66, the high values been associated with Semimembranosus and Gluteobiceps muscles. The present study demonstrates that there are differences in meat quality characteristics of meat from SEA goats and their crosses with Norwegian breeds finished under small scale farming conditions in rural areas. Therefore, concentrate supplementation of goats of both breeds improves meat quality attributes.

• Food Science and Preservation
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• v.22 no.1
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• pp.44-50
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• 2015

This study was performed to optimize the preparation of frozen lotus roots. Prior to freezing, an optimal blanching condition at $100^{\circ}C$ for 5 min was established, based on the microbial growth, texture, total phenolic content (TPC), and sensory evaluation results. The blanched samples were then frozen under various freezing conditions ($-20^{\circ}C$ in a freezer for 2 hr, $-70^{\circ}C$ in a gas nitrogen convection chamber for 7 min, and $-196^{\circ}C$ in liquid nitrogen for 20 sec), and their qualities after thawing were determined. The scanning electron microscopic analysis indicated that the microstructure of the sample frozen at $-70^{\circ}C$ was similar to that of the control sample, compared with the other freezing conditions (-20 and $-196^{\circ}C$). The antioxidant activities of the frozen samples decreased compared to those of the control, but there was no significant (p<0.05) difference among the treatments. In terms of TPC, the samples frozen at -70 and $-196^{\circ}C$ had significantly (p<0.05) higher values than the sample frozen at $-20^{\circ}C$. In addition, the drip loss of the sample frozen at $-20^{\circ}C$ was higher than those of the other frozen samples. These results suggest that freezing at $-70^{\circ}C$ in a gas nitrogen convection chamber can be an optimal freezing method of producing high-quality frozen lotus roots.

• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.93-100
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• 2024

Pore water freezes in low-temperature compaction, which leads to different compaction characteristics compared to room temperature conditions. In regions like Alberta, Canada, where organic soils are prevalent, compaction performance is influenced by the high water retention and compressibility of organic soils, as well as their sensitivity to freezing and thawing. Alberta's strict environmental regulations demand the reuse of excavated soil for backfill, and the long winter season creates challenging conditions for civil engineering projects. In this study, a laboratory compaction test was conducted to evaluate the low-temperature compaction characteristics of organic soils with varying organic content. The results indicate that the optimum moisture content increases as the organic content increases, and the maximum dry unit weight decreases by up to 21.9%. In addition, under temperature conditions below -4℃, no optimum moisture content was observed, and the dry unit weight decreased as the moisture content increased.