• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3602-3609
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• 2015

HPFRCC is characterized by a very low water-to-binder ratio which induce extremely large autogenous shrinkage at early age. The restriction of such autogenous shrinkage through the use of forms and reinforcing bars will increase substantially the risk of excessive residual stresses and shrinkage cracking. The exact understanding of the shrinkage behavior and studies on solutions to reduce shrinkage should be imperatively undertaken for further application of HPFRCC to real structures. Therefore, this paper investigated the mechanical properties of HPFRCC with respect to the eventual introduction of expansive admixture(EA) and shrinkage reducing agent (SRA) in the mixture. Autogenous shrinkage test was conducted considering the coefficient of thermal expansion (CTE) measured at early age so as to examine the effects of EA and SRA on the autogenous shrinkage behavior of HPFRCC.

• Food Engineering Progress
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• v.13 no.2
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• pp.105-109
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• 2009

The effects of drying methods on the physicochemical properties of Salicornia herbacea powder were investigated. Samples prepared by freeze drying showed a significantly higher L$^{*}$-value but lower a$^{*}$-value as compared with those prepared by hot-air drying and vacuum drying (p<0.05). Scanning electron micrograph revealed that freeze drying produced more orderly and denser samples than did vacuum and hot-air drying. Water solubility of the freeze-dried sample was significantly higher than those of the other methods while swelling ratio of the same sample was significantly lower than those of others (p<0.05). Freeze-dried Salicornia herbacea powder contained significantly higher amounts of total sugar and reducing sugar as compared to the other samples (p<0.05).

• Smart Structures and Systems
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• v.24 no.4
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• pp.541-552
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• 2019

Construction development and greenhouse gas emissions have globally required a strategic management to take some steps to stain and maintain the environment. Nowadays, recycled aggregates, in particular ceramic waste, have been widely used in concrete structures due to the economic and environmentally friendly solution, requiring the knowledge of recycled concrete. Also, one of the materials used as a substitute for concrete cement is wollastonite mineral to decrease carbon dioxide (CO2) from the cement production process by reducing the concrete consumption in concrete. The purpose of this study is to investigate the effect of wollastonite on the mechanical properties and durability of conventional composite concrete, containing recycled aggregates such as compressive strength, tensile strength (Brazilian test), and durability to acidic environment. On the other hand, in order to determine the strength and durability of the concrete, 5 mixing designs including different wollastonite values and recovered aggregates including constant values have been compared to the water - cement ratio (w/c) constant in all designs. The experimental results have shown that design 5 (containing 40% wollastonite) shows only 6.1% decrease in compressive strength and 4.9% decrease in tensile strength compared to the control plane. Consequently, the use of wollastonite powder to the manufacturing of conventional structural concrete containing recycled ceramic aggregates, in addition to improving some of the properties of concrete are environmentally friendly solutions, providing natural recycling of materials.

• Journal of the Korea Institute of Building Construction
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• v.19 no.2
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• pp.139-147
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• 2019

In this study, an experiment was conducted to evaluate the properties of cement matrix using diatomite and silica gel as adsorbents of radon. The adsorption properties of diatomite of a natural adsorbent and silica gel of an artificial sorbent were examined to confirm the reduction of radon gas concentration of the removal of radon gas in the indoor environment of the human body. We conducted a performance evaluation for the study. The fluidity, air content, density, absorption, flexural failure load, thermal conductivity and radon gas concentration of the specimen using diatomite and silica gel were measured. the fluidity and the air content of the adsorbed matrix with diatomite were decreased as the diatomite replacement ratio increased. Which seems to affect the subsequent matrix by the absorption of the compounding water of diatomite. As the replacement rate of silica gel increased, the fluidity decreased and the air content increased up to constant replacement rate. It is judged that the surface of the silica gel has a critical point at which it can react with moisture.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.8
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• pp.51-58
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• 2018

G-SEED has been introduced with the aim of reducing energy use and resources since 2002, as the system of certificating environmental friendliness of buildings to create comfortable environment. This study analyzed the changes of certification standard of G-SEED since the revision in 2016, comparing certification results of office buildings by grade, category and certification items between G-SEED 2013-2 version and revised version of 2016. Also, this study analyzed the average points and their standard deviation of certification items including both deleted items and newly added items and extracted items needed to be reviewed in the future revision. In the revision, G-SEED has been extended its certification system to involve existing buildings and Innovative Design categories newly introduced with revising the certification items and difficulties. In revised version of G-SEED, the certification grade appeared to change its acquisition ratio decreasing Green2 and increasing Green4, during Green1 and Green3 were similar in proportion. The average scores by categories appeared decrease in Energy and Environmental Pollution category and Materials and Resources category, on the other hand, Maintenance category appeared the highest increase in the average score. Otherwise, Land Use and Transportation, Water Circulation, Ecology, Indoor Environment categories appeared similar average scores both version of G-SEED. In addition, the Innovative Design which was newly introduced category, seems to expect gradual gaining high scores according to technology development in future, although its possession has shown lower scores in revised version.

• Journal of Soil and Groundwater Environment
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• v.26 no.1
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• pp.54-64
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• 2021

The chemical warfare agents (CWAs) have been developed for offensive or defensive purposes and used as chemical weapons in war and terrorism. The CWAs are exposed to the natural environment, transported through the water system and then eventually contaminate soil and groundwater. Therefore, effective decontamination technology to remediate CWAs are needed. The CWAs are extremely dangerous and prodution is strictly prohibited, therefore, it is difficult to use CWAs even in experimental purpose. In this study, 2,4-dichlorophenoxyacetic acid (2,4-D) was chosen as a model representative CWA because it is a simulant of anti-plant CWAs and one of the major component of agent orange. The optimum degradation conditions such as oxidant:activator ratio were determined. The effects of hydroxylamine and chelating agents such as citric acid (CA), oxalic acid (OA), malic acid (MA), and EDTA addition to increase Fe2+ activation were also investigated. Scavenger experiments using tert-butyl alcohol (TBA) and ethanol confirmed that although both sulfate (SO4•-) and hydroxyl radical (•OH) existed in Fe2+-persulfate system, sulfate radical was the predominant radical. To promote the Fe2+ activator effect, the effect of hydroxylamine as a reducing agent was investigated. In chelating agents assisted Fe2+-persulfate oxidation, the addition of 2 mM of CA and MA enhanced 2,4-D degradation. In contrast, EDTA and OA inhibited the 2,4-D removal due to steric hindrance effect.

• Journal of Medicine and Life Science
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• v.20 no.2
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• pp.83-88
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• 2023

Metal artifacts cause inaccuracies in target delineation, radiation treatment planning, and delivery when computed tomography images of a radiotherapy patient implanted with a high-density material in the body are acquired. In this study, we investigated the possibility of obtaining improved images in clinical trials through metal artifact reduction using silicon impression materials without the need for a specific metal artifact reduction algorithm. A silicon impression material exhibiting a constant Hounsfield unit (HU) value according to the mixing ratio of the catalysts and bases was selected. The material did not exhibit any change in weight or shape over time. For both the instances of inserting the metal material and applying the silicon impression material, the HU value and dose were compared with homogeneous cases filled with water-equivalent materials. When the silicon impression material was applied to the region where the high-density material was located, the HU value was within 5% and the dose was within 3% compared with those of the homogeneous cases. In this study, the silicon impression materials reduced metal artifacts. However, because the composition, shape, size, and location of high-density materials differ, further studies are required to consider these factors in clinical applications.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.267-273
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• 1977

Rainbow trout were reared in a small indoor aquarium which was equipped with a simple recirculating biofilter combined with a small amount of inflowing water for 199 days from April 25 to November 10, 1977 in Busan where very hot summer air temperature is encountered, and results obtained were promissing as following; 1. The aquarium has dimensions of $1m\;\times\;1m\;\times\;67cm(depth)$, and a bottom center sedimentation chamber of conical type through which out-flowing water is pushing fecal matter and other detritus outward. The conical sedimentation chamber measures 20 cm depth and 20 cm diameter at its upper mouth and tapers to the bottom end which is connected to 4 cm diameter draining pipe. The draining pipe goes through under the tank and then is elevated on the side. The water depth was maintained at about 40 cm depth by adjusting the heigh of draining pipe. The filter bed contained 16 l of $3\~5\;mm$ zeolite gravels, and water circulation rate was about 1030 l/hr. 2. Continuous inflowing water resulted in a good elimination of waste materials through its outflowing water thus reducing waste loading in the filter. 3. Mean temperature of water in the rearing aquarium containing about 400 l water volume was maintained at around 20 to $22^{\circ}C$ by 0.59 l/min of the inflowing well water which usually maintained the temperature of $17^{\circ}C$ during the hot summer season from the first of July to the first of October when the 10-days-mean air temperature ranged from $20^{\circ}\;to\;27.3^{\circ}C$ $(total\;mean\;24.6^{\circ}C) $ and under this condition the fish continued normal growth. 4. The production per 1 l/min of inflowing water with this simple biofilteration reached 30 hg. 5. The total cost including all feed and power during this experimental rearing period fell well within the economic establishment and if the feed and filteration system are improved the benefit-cost ratio will be much increased.

• Journal of the Korea Concrete Institute
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• v.23 no.5
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• pp.581-590
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• 2011

Since ultra-high performance cementitious composites (UHPCC) not only represents high early age shrinkage strain due to its low water-to-binder ratio (W/B) and high fineness admixture usage but also reduces the cross section of structure from the higher mechanical properties, it generally has more shrinkage cracks from the restraints of formwork and reinforcing bars. In this study, free and restrained shrinkage experiments were conducted to evaluate the suitability of incorporating both expansive admixture (EA) and shrinkage reducing agent (SRA). The test results indi-cated that approximately 40~44% of free shrinkage strain was decreased. Also, the results showed that 35% and 47% of residual tensile stresses were relieved by synergetic effect of SRA and EA, respectively. Residual tensile stresses from ringtest were relaxed by approximately 61% and 64% of elastic shrinkage stresses due to SRA and EA, respectively, because of the tensile creep effect. Therefore, the creep effect should be considered to precisely estimate the restrained shrinkage behavior of concrete structures. The degree of restraint of UHPCC was approximately in the range of 0.78~0.85. The addition of combined EA and SRA showed minute influence on the degree of restraint. However, the effect decreased when thicker concrete ring was used. Tensile creep strains were measured and compared to the predicted values from 4-parametric prediction model considering time dependent restrained forces.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.11
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• pp.1805-1812
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• 2013

The quality and sensory characteristics of Misutkarus, made from immature-whole green rice (IWGR) and barley (IWGB), and their cookies were assessed. Misutkarus of IWGR and IWGB showed a significantly higher water absorption index and viscosity, as well as higher hydrolysis rate by ${\alpha}$-amylase, resulting in higher amount of reducing sugar than those of mature brown rice and barley. The cookies made with 30% Misutkarus of IWGR and IWGB showed harder texture, lower spread ratio, darker and more reddish color than cookies with 100% wheat flour (control). For sensory evaluation, the beverage was prepared by mixing Misutkarus, milk and honey, and the beverages of IWGR and IWGB could not provide acceptable sensory quality due to reduced nutty taste and stronger greenish aroma. However, when added to prepare cookies, 30% Misutkarus of IWGB imparted the favorable taste, aroma, texture and overall preference by presenting no significantly different sensory characteristics with wheat flour.