• Journal of the Korea Institute of Building Construction
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• v.21 no.3
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• pp.181-188
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• 2021

In this study, the various performance of dry cement mortar for Korean floor heating system depending on water-to-dry mortar ratios (W/DM) applied in project site was evaluated. According to the experiment conducted, the importance of mixing water for dry cement mortar was revealed by resultant performance or quality of the dry cement mortar for floor finishing by changing W/DM controlled in project site by workers. As the general trend, the flow was increased, and the unit volume weight was decreased with increasing W/DM. Additionally, compressive strength and drying shrinkage were significantly influenced by W/DM. Hence, it can be stated that the adding water for dry cement mortar should be managed precisely since excessively increased W/DM for workability improvement can cause performance degradation of floor mortar with the failures such as excessive bleeding, and severe segregation during the fresh state. As a summary of the study, to achieve a desirable performance of dry cement mortar, approximately 20 % of W/DM can be suggested to be managed in project site.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.1
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• pp.24-33
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• 1987

Competitive ability and response of grain yield in a mixed cropping of two cultivars having different agronomic traits were evaluated at the Yeongnam Crop Experiment Station in 1984 and 1985. Competitive ability was higher in Indica x Japonica cultivar, Milyang 23, and tall statured cultivar, Samgang-byeo, than in Japonica type cultivar, Nacdongbyeo, short statured type cultivar, Taebaegbyeo, respectively. Compared to pure stand, more grain yield was recorded when mixture rates were over 50% in a seed volume for the mixing rate of high yielding cultivar in two cultivars, but low compared to pure cultivation of the cul-tivar having the higher yielding ability in two cultivars.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.47-59
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• 2024

Purpose: This study aims to propose measures for the prevention of fire and explosion accidents within manufacturing facilities by improving the existing classification criteria for hazardous locations based on the leakage patterns of flammable liquids. The objective is to suggest ways to safely manage ignition sources and combustible materials. Method: The hazardous locations were calculated using "KS C IEC 60079-10-1," and the calculated explosion hazard distances were visualized in 3D. Additionally, the formula for the atmospheric dispersion of flammable vapors, as outlined in "P-91-2023," was utilized to calculate the dispersion rates within the hazardous locations represented in 3D. Result: Visualization of hazardous locations in 3D enabled the identification of blind spots in the floor plan, facilitating immediate recognition of ignition sources within these areas. Furthermore, when calculating the time taken for the Lower Explosive Limit (LEL) to reach within the volumetric space of the hazardous locations represented in 3D, it was found that the risk level did not correspond identically with the explosion hazard distances. Conclusion: Considering the atmospheric dispersion of flammable liquids, it was concluded that safety management should be conducted. Therefore, a method for calculating the concentration values requiring detection and alert based on realistically achievable ventilation rates within the facility is proposed.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.2
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• pp.57-65
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• 2008

Wastewater containing strong organic matter is very difficult to treat by utilizing general sewage treatment plant. but the wastewater is adequate to generate biomass energy (bio-gas; methane gas) by utilizing anaerobic digestion. EcoDays Plug Flow Reactor (E-PFR), which was already proved as an excellent aerobic wastewater treatment reactor, was adapted for anaerobic food wastewater digestion. This research was performed to improve the efficiency of bio-gas production and to optimize anaerobic wastewater treatment system. Food wastewater from N food waste treatment plant was applied for the pilot scale experiments. The results indicated that the efficiency of anaerobic wastewater treatment and the volume of bio-gas were increased by applying E-PFR to anaerobic digestion. The structural characteristics of E-PFR can cause the high efficiency of anaerobic treatment processes. The unique structure of E-PFR is a diaphragm dividing vertical hydraulic multi-stages and the inversely protruded fluid transfer tubes on each diaphragm. The unique structure of E-PFR can make gas hold-up space at the top part of each stage in the reactor. Also, E-PFR can contain relatively high MLSS concentration in lower stage by vertical up-flow of wastewater. This hydraulic flow can cause high buffering capacity against shock load from the wastewater in the reactor, resulting in stable pH (7.0~8.0), relatively higher wastewater treatment efficiency, and larger volume of bio-gas generation. In addition, relatively longer solid retention time (SRT) in the reactor can increase organic matter degradation and bio-gas production efficiency. These characteristics in the reactor can be regarded as "ideal" anaerobic wastewater treatment conditions. Anaerobic wastewater treatment plant design factor can be assessed for having 70 % of methane gas content, and better bio-gas yielding and stable treatment efficiency based on the results of this research. For example, inner circulation with generated bio-gas in the reactor and better mixing conditions by improving fluid transfer tube structure can be used for achieving better bio-gas yielding efficiency. This research results can be used for acquiring better improved regenerated energy system.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.785-792
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• 2005

This study is to examine the influence of defective grain shape of coarse aggregate and lowered fineness modulus of fine aggregate on the characteristics of high flowing concrete. The flow ability and compact ability of high flowing concrete was examined using fine aggregate, varying its fineness modulus to 2.0, 2.5, 3.0, and 3.5, and coarse aggregate with before and after grain shape improvement. Also the influence of fineness modulus of fine aggregate and grain shape of coarse aggregate on dispersion distance of particles of aggregate was examined by relatively comparing the dispersion distance between particles of aggregate. According to the experimental result, minimum porosity when mixing fine aggregate and coarse aggregate was shown in order of fineness modulus of fine aggregate, 3.0, 2.5, 2.0, 3.5, regardless of the improvement of grain shape. So when the fineness modulus is bigger or smaller than KS Standard $2.3\~3.1$, the porosity increased. When the spherical rate of the grain shape of coarse aggregate unproved from 0.69, a disk shape to 0.78 sphere shape, the rate of fine aggregate, which represents minimum porosity, decreased $6\%$ from $47\%\;to\;41\%$. The 28 days compressive strength according to fineness modulus of fine aggregate increased about 3 ma as the fineness modulus increased from 2.0 to 2,5, and 3.0. However, the 28 days compressive strength decreased about 9 ma at 3.5 fineness modulus as compared with 3.0 fineness modulus. The improvement of grain shape in coarse aggregate and increase of fineness modulus in fine aggregate made the flow ability, compact ability, and V-rod flowing time improve. Also the fineness modulus of fine aggregate increased the paste volume ratio when a higher value was used within the scope of KS Standard $2.3\~3.1$.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.1
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• pp.53-66
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• 1980

The research work is concerned with the analytical and experimental studies on the heat transfer phenomenon around the underground concrete digester used for biogas production Systems. A mathematical and computational method was developed to estimate heat losses from underground cylindrical concrete digester used for biogas production systems. To test its feasibility and to evaluate thermal parameters of materials related, the method was applied to six physical model digesters. The cylindrical concrete digester was taken as a physical model, to which the model,atical model of heat balance can be applied. The mathematical model was transformed by means of finite element method and used to analyze temperature distribution with respect to several boundary conditions and design parameters. The design parameters of experimental digesters were selected as; three different sizes 40cm by 80cm, 80cm by 160cm and l00cm by 200cm in diameter and height; two different levels of insulation materials-plain concrete and vermiculite mixing in concrete; and two different types of installation-underground and half-exposed. In order to carry out a particular aim of this study, the liquid within the digester was substituted by water, and its temperature was controlled in five levels-35。 C, 30。 C, 25。 C, 20。C and 15。C; and the ambient air temperature and ground temperature were checked out of the system under natural winter climate conditions. The following results were drawn from the study. 1.The analytical method, by which the estimated values of temperature distribution around a cylindrical digester were obtained, was able to be generally accepted from the comparison of the estimated values with the measured. However, the difference between the estimated and measured temperature had a trend to be considerably increased when the ambient temperature was relatively low. This was mainly related variations of input parameters including the thermal conductivity of soil, applied to the numerical analysis. Consequently, the improvement of these input data for the simulated operation of the numerical analysis is expected as an approach to obtain better refined estimation. 2.The difference between estimated and measured heat losses was shown to have the similar trend to that of temperature distribution discussed above. 3.It was found that a map of isothermal lines drawn from the estimated temperature distribution was very useful for a general observation of the direction and rate of heat transfer within the boundary. From this analysis, it was interpreted that most of heat losses is passed through the triangular section bounded within 45 degrees toward the wall at the bottom edge of the digesten Therefore, any effective insulation should be considered within this region. 4.It was verified by experiment that heat loss per unit volume of liquid was reduced as the size of the digester became larger For instance, at the liquid temperature of 35˚ C, the heat loss per unit volume from the 0. 1m$^3$ digester was 1, 050 Kcal/hr m$^3$, while at for 1. 57m$^3$ digester was 150 Kcal/hr m$^3$. 5.In the light of insulation, the vermiculite concrete was consistently shown to be superior to the plain concrete. At the liquid temperature ranging from 15。 C to 350 C, the reduction of heat loss was ranged from 5% to 25% for the half-exposed digester, while from 10% to 28% for the fully underground digester. 6.In the comparison of heat loss between the half-exposed and underground digesters, the heat loss from the former was fr6m 1,6 to 2, 6 times as much as that from the latter. This leads to the evidence that the underground digester takes advantage of heat conservation during winter.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.9
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• pp.1245-1250
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• 2006

This study was carried out to develop the method of preparing lecithin-fortified ginseng extract. Firstly, soybean lecithin was mixed with soybean oil (LCS) in varying ratio (2.5%, 5%, 10% and 20%). Then, one part volume of LCS was mixed with three parts volume of ginseng extract with 10% solid matter content and the mixture was vortexed vigorously. Finally, the mixture was spinned at the speed of 3,000 rpm for 30 minutes to separate oil and aqueous ginseng extract layer (AG). AG was then subjected to qualitative and quantitative analysis of phospholipids and ginsenosides. Fatty acid composition and crude fat content before and after LCS was determined. Stability of lecithin in ginseng extract was determined by analyzing phospholipid content in the one third upper and lower layer of the concentrated AG in Falcon tubes while storing the LCS treated concentrated AG in 4, 25 and 40oC for 6 months. Ratio of lecithin transferred to AG increased with the increase in lecithin content of soybean oil. There was no significant change in fatty acid composition and crude fat content, and ginsenoside content in the ginseng extract before and after LCS treatment. TLC and HPLC pattern of saponin fraction before and after treating the ginseng extract with LCS demonstrated no observable difference. There was no change in lecithin content in the upper and lower one third layer of ginseng extract in the tubes after storing the concentrated AG in 4, 25 and $40^{\circ}C$ for 6 months. Ginsenosides HPLC pattern was not changed when stored the LCS-treated ginseng extract in those conditions for six months, indicating satisfiable stability of the LCS-treated concentrated ginseng extract. From these results, it can be concluded that treatment of the ginseng extract with lecithin containing soybean oil is a labor effective method with satisfiable stability to fortify lecithins to ginseng extract.

• Korean Journal of Breeding Science
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• v.41 no.2
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• pp.130-136
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• 2009

"Hanbaek", a white winter wheat (Triticum aestivum L.) cultivar was developed by the National Institute of Crop Science, RDA. It was derived from the cross "Shan7859/Keumkang"//"Guamuehill" during 1996. "Hanbaek" was evaluated as "Iksan314" in Advanced Yield Trial Test in 2005. It was tested in the regional yield trial between 2006 and 2008. "Hanbaek" is an awned, semi-dwarf and hard winter wheat, similar to "Keumkang" (check cultivar). The heading and maturing date of "Hanbaek" were similar to that of "Keumkang". Culm and spike length of "Hanbaek" were 89 cm and 9.0 cm, which longer culm length and spike length than "Keumkang" (80 cm and 7.9 cm, respectively). "Hanbaek" had lower test weight (797 g) and higher 1,000-grain weight (47.7 g) than "Keumkang" (813 g and 44.9 g, respectively). "Hanbaek" showed resistance to winter hardiness and susceptible to pre-harvest sprouting, which lower withering rate on the high ridge (4.4%) and higher rate of pre-harvest sprouting (47.9%) than "Keumkang" (21.9% and 30.4%, respectively). "Hanbaek" had similar flour yield (74.4%) to "Keumkang" (74.1%) and higher ash content (0.45%) than "Keumkang" (0.42%). "Hanbaek" showed lower lightness (89.13) and similar redness and yellowness (-0.87 and 10.93) in flour color than "Keumkang" (90.02, -1.23 and 9.28, respectively). It showed similar protein content (12.8%) SDS-sedimentation volume (63.0 ml) and gluten content (10.8%) to those of "Keumkang" (11.9%, 62.3 ml and 10.2%, respectively). It showed lower water absorption (59.6%) and mixing time (3.8 min) in mixograph and higher fermentation volume (1,350 ml) than those of "Keumkang" (60.6%, 4.7 min and 1,290 ml, respectively). Amylose content and pasting properties of "Hanbaek " were similar to those of "Keumkang". "Hanbaek" showed same compositions in high molecular weight glutenin subunits (HMW-GS, 2*, 13+16, 2+12), granule bound starch synthase (Wx-A1a, Wx-B1a, and Wx-D1a) and puroindolines (Pina-D1a/Pinb-D1b) compared to "Keumkang". "Hanbaek" showed lower hardness (4.22N) and similar springiness and cohesiveness of cooked noodles (0.94 and 0.63) to those of "Keumkang" (4.65N, 0.93 and 0.64, respectively). Average yield of "Hanbaek" in the regional adaptation yield trial was 5.98 MT/ha in upland and 5.05 MT/ha in paddy field, which was 8% and 6% higher than those of "Keumkang" (5.55 MT/ha and 4.77 MT/ha, respectively). "Hanbaek" would be suitable for the area above the daily minimum temperature of $-10^{\circ}C$ in January in Korean peninsula.

• Economic and Environmental Geology
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• v.54 no.2
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• pp.285-297
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• 2021

Globally, nuclear-decommissioning facilities have been increased in number, and thereby hundreds of thousands of wastes, such as concrete, soil, and metal, have been generated. For this reason, there have been numerous efforts and researches on the development of technology for volume reduction and recycling of solid radioactive wastes, and this study reviewed and examined thoroughly such previous studies. The waste concrete powder is rehydrated by other processes such as grinding and sintering, and the processes rendered aluminate (C3A), C4AF, C3S, and ��-C2S, which are the significant compounds controlling the hydration reaction of concrete and the compressive strength of the solidified matrix. The review of the previous studies confirmed that waste concretes could be used as recycling cement, but there remain problems with the decreasing strength of solidified matrix due to mingling with aggregates. There have been further efforts to improve the performance of recycling concrete via mixing with reactive agents using industrial by-products, such as blast furnace slag and fly ash. As a result, the compressive strength of the solidified matrix was proved to be enhanced. On the contrary, there have been few kinds of researches on manufacturing recycled concretes using soil wastes. Illite and zeolite in soil waste show the high adsorption capacity on radioactive nuclides, and they can be recycled as solidification agents. If the soil wastes are recycled as much as possible, the volume of wastes generated from the decommissioning of nuclear power plants (NPPs) is not only significantly reduced, but collateral benefits also are received because radioactive wastes are safely disposed of by solidification agents made from such soil wastes. Thus, it is required to study the production of non-sintered cement using clay minerals in soil wastes. This paper reviewed related domestic and foreign researches to consider the sustainable recycling of concrete waste from NPPs as recycling cement and utilizing clay minerals in soil waste to produce unsintered cement.

• Korean Journal of Food Science and Technology
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• v.33 no.4
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• pp.437-443
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• 2001

Gastrodia elata blume (GEB) is considered to be a useful herbal medicine in oriental countries for the treatment of headache, migraine, dizziness, childhood convulsion, epilepsy, rheumatism, hypertension, neuralgia and neurological disorders. This study was carried out to investigate the quality of bread added with the powder of GEB. The possibility of GEB wheat flour mixture as bread was studied by adding 0%, 0.5%, 1.0%, 1.5%, 2.0% of GEB powder to wheat flour. In Farinograph data, the dough stability decreased with the increase of GEB powder. Granular size of starches ranged from $36\;{\mu}m\;to\;60{\mu}m$, and the shape of them showed a long oval figure. Amylograph showed that the increase in the ratio of GEB on the doughs slightly elevated in the maximum viscosity. The loaf volume of 0.5% powder increased by 10.2% but that of 2.0% decreased by 16.8%. The moisture content was 43.57% in the control but it increased as the powder addition. The colors of crust and crumb were not significantly different among L, b and ${\Delta}E$, but 'a' value in crumb was increased as the powder addition. The addition of the powder had no significant effect on bread texture. In sensory evaluation, the moistness increased as the increase of the powder addition. The control bread was most excellent, and the bread made by mixing additives were better than just 0.5% GEB-wheat flour in terms of quality.