• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.51-59
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• 2021

In this study, the purpose of this study was to quantitatively grasp the specific correlation between the raw material and the occurrence of leakage by analyzing the characteristics of leakage by adjusting the type and content of the raw material constituting the asphalt mastic coating waterproofing material. To this end, two raw materials, CA (calcium carbonate) and ASE (anti-sedimentation), which are organic and mineral extender for asphalt mastic waterproofing membrane coating, were selected. viscosity and oil leakage stability (20 ℃, 40 ℃) was evaluated. As a result of the evaluation, the oil leakage stability and viscosity were inversely proportional to the CA average particle size, and it was quantitatively proven that a correlation in proportion to the ASE content was established. The results of this study are expected to be used as core data for basic mixing design in the future mixing studies to improve leakage of asphalt mastic waterproofing membrane coating.

• Journal of Digital Convergence
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• v.18 no.7
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• pp.85-92
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• 2020

The purpose of this study is to compare and analyze the differences in employment trends between enterprises and job seekers related to the 4th Industrial Revolution, focusing on the 11 elements of recruitment process. As a method of analysis, a methodology suitable for the convergence research methodology was used by mixing social network analysis and variance analysis, and significant results were derived. First, while large enterprises emphasized organizational culture and job analysis, small enterprises emphasized an interview from the perspective of practitioners. Second, in both manufacturing and service industries, enterprises emphasized interviews and documents, but job seekers emphasized job analysis. Third, the proportion of the recruitment process was found to be greater in the manufacturing industry than in the service industry. Fourth, it was found that enterprises accounted for a larger proportion of the recruitment process than job seekers. This showed an interaction effect between the subject and the industry sector. Therefore, the evaluation of the recruitment process between enterprises and job seekers was found to be very different.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.36 no.5
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• pp.105-116
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• 2020

In this study, the royal protocols of the Joseon Dynasty, known as uigwes, were reviewed to clarify the materials and structure of Korean traditional walls. For this, the Yeonggeon-and Sanreng-uigwes were thoroughly reviewed, and then the names, materials, and construction methods of the traditional walls were systematically organized. In addition, mix proportions of plastering materials used in the walls were estimated based on the records in the uigwes; these were compared with the ratios specified in the current specifications. As a result of the comprehensive review, it was found that the mix proportions of the plastering materials varied depending on importance of buildings, type of walls, and the raw materials. Based on this, it was concluded that the characteristics of each uigwe should be considered when studying the mix proportion of materials for the traditional walls. It was also found that there were differences between the traditional and modern specifications for the wall constructions. That is, historical records and the specifications currently used were different in terms of constituent materials, construction methods and mix proportions. As a cause of the difference, the disconnection of the traditional methods and the introduction of foreign plastering techniques during the rapid social change in the 20th century were suggested.

• Advances in concrete construction
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• v.13 no.1
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• pp.71-81
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• 2022

Aluminosilicate materials as precursors are heterogenous in nature, consisting of inert and partially reactive portion, and have varying proportions depending upon source materials. It is essential to assess the reactivity of precursor prior to synthesize geopolymers. Moreover, reactivity may act as decisive factor for setting molar concentration of NaOH, curing temperature and setting proportion of different precursors. In this experimental work, the reactivities of two precursors, low calcium (fly ash (FA)) and high calcium (ground granulated blast furnace slag (GGBS)), were assessed through the dissolution of aluminosilicate at (i) three molar concentrations (8, 12, and 16 M) of NaOH solution, (ii) 6 to 24 h dissolution time, and (iii) 20-100℃. Based on paratermeters influencing the reactivity, different proportions of ternary binders (two precursors and ordinary cement) were activated by the combined NaOH and Na2SiO3 solutions with two alkaline activators to precursor ratios, to synthesize the geopolymer. Reactivity results revealed that GGBS was 20-30% more reactive than FA at 20℃, at all three molar concentrations, but its reactivity decreased by 32-46% with increasing temperature due to the high calcium content. Setting time of geopolymer paste was reduced by adding GGBS due to its fast reactivity. Both GGBS and cement promoted the formation of all types of gels (i.e., C-S-H, C-A-S-H, and N-A-S-H). As a result, it was found that a specified mixing proportion could be used to improve the compressive strength over 30 MPa at both the ambient and hot curing conditions.

• The Korean Journal of Food & Health Convergence
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• v.9 no.4
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• pp.1-10
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• 2023

This study examined the quality characteristics to evaluate the optimal mixing ratio of a chlorella powder in Cheongpomuk. The total polyphenol and total flavonoids contents of Cheongpomuk and chlorella powder was 279.90 ㎍/mL, 489.50 ㎍/mL and 48.79 ㎍/mL, 687.85 ㎍/mL respectively. The DPPH free radical scavenging activities and ABTS radical scavenging activities of chlorella powder was 65.39%, 91.28% respectively. The L values (58.85~26.23), a values (-0.44~-5.84) of the Hunter's color values decreased and b value (-10.98 ~4.12) increased significantly in proportion to the amount of chlorella powder. The total polyphenol contents (55.00~734.20 ㎍/mL), total flavonoids contents (41.00~88.29 ㎍/mL), DPPH free radical scavenging activities (35.10~65.50%) and ABTS radical scavenging activities (50.29~92.86%) of Cheongpomuk increased significantly in groups of chlorella powder. In the physical properties, the hardness (135.93~103.93 g/㎠), chewiness (6.76~3.76 g), springiness (4.92~4.36 %), and gumminess (147.70~94.23) of Cheongpomuk decreased significantly in proportion to the amount of chlorella powder. The Cheongpomuk containing 15% chlorella powder showed a high score with regard to color, flavor, moistness, chewiness and overall acceptance. The appropriate addition amount of chlorella powder for making Cheongpomuk is 15%. This study indicate that Cheongpomuk treated with chlorella powder had the highest functional component and antioxidant activity.

• Journal of the Korean GEO-environmental Society
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• v.16 no.2
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• pp.15-25
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• 2015

As the physical and mechanical properties of lightweight air-mixed soil change in the procedure of transportation of mix truck, it is necessary to assure whether the properties during construction satisfy those in design. In this study, variations of properties of mixed soil after transportation by mix truck are proved by field test. Lightweight air-mixed soil used field test the unit weight of $9.0{\pm}1.0kN/m^3$, the flow value of $190{\pm}20mm$ was produced. To analyze variations of properties of mixed soil the unit weight and flow value of the sample before and after transport was measured unconfined compressive strength tests were performed. Mixing time was 19~175 minutes diversified. As the test results, it is known that the density, the flow value and the unconfined compressive strength of lightweight air-mixed soil change by transportation, but these values satisfy the specifications of material of air-mixed soil. After transportation the average value of the unit weight and flow value change in the flow of the $(+)0.10kN/m^3$, 4.8 mm respectively, the average change in the unit weight and the flow value due to the mixing time was constant. And unconfined compressive strength of 28-day specimen increases from 20 to $150kN/m^2$. But, these values do not have some clear relationship with the transportation time within 175 minutes which is longest test time. Consequently, Within 175 minutes the changes of properties by transportation are too small to show some problems in the construction field.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.689-697
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• 2005

Hydrogen peroxide is a reservoir of OH radical which is the powerful oxidant in the atmosphere. Therefore, the status of the oxidizing atmosphere could be reflected on the concentration of $H_{2}O_{2}$. In this study, the distribution of $H_{2}O_{2}$ was determined during the intensive aircraft measurements over the Yellow sea in March, December 2002, April, November 2003 and March, October 2004. Flights covered from $124^{circ}E\;to\;129^{circ}E\;and\;35^{circ}N\;to\;37^{circ}N$, and extending to 3,000 m. The flight patterns were set properly to assess the altitudinal and longitudinal distribution for $H_{2}O_{2}$. $H_{2}O_{2}$ was extracted onto aqueous solution using a continuously flowing glass coil and analyzed by a high performance liquid chromatography (HPLC) accompanied with a fluorescence detector using postcolumn enzyme derivatization. Mixing ratios of $O_{3},\;NO_{x}\;and\;SO_{2}$ were measured in real time by commercial analysis instruments. Along the heights, the maximum concentration of $H_{2}O_{2}$ appeared around 1,500 m then gradually decreased with increasing altitude. The vertical behavior of ozone showed the similar trend to $H_{2}O_{2}$. The mean mixing ratio of $NO_{x}$ was about 2 ppbv and not showed clear vertical distribution patterns. The mean value of was the same as $NO_{x}$ however $SO_{2}$ appeared extreme concentration in low altitude. $H_{2}O_{2}\;and\;O_{3}$ showed even longitudinal distribution however $NO_{x}$ mixing ratio in land ($127^{circ}E$) was much higher than over the sea. $SO_{2}$ rather decreased with increasing longitude. $H_{2}O_{2}$ was in inverse proportion to $NO_{x}$ in spring and summer and $SO_{2}$ in spring, which indicated its significant role to NO and $SO_{2}$ oxidation pathways.

• Asian-Australasian Journal of Animal Sciences
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• v.2 no.2
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• pp.115-121
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• 1989

A comparative slaughter feeding experiment with steer calves weighing 280 kg and a concurrent digestion trial with wether lambs was conducted to study the energy value of rice straw as influenced by ammonia treatment and mixing with alfalfa hay. Steers were ad libitum fed one of nine completely mixed experimental diets: basal (high concentrate); 25 or 50% of untreated rice straw (URS) or ammoniated (plastic covered bales, 4.6% $NH_3$ by weight) rice straw (ARS) proportionately replacing part of the basal; a 50:50 % mixture of URS or ARS and alfalfa replacing a proportion of the basal at 25 and 50%. Digestibility of the nine complete diets (pelleted to prevent sorting) was determined with four ad libitum fed lambs. Ammoniation increased crude protein level (from 3.6 to 10.8%) and in vitro dry matter digestibility of the rice straw by 15%. The improvement in DE, NEm and NEg by ammoniation of rice straw was 20, 52 and 117%, respectively. Ammoniation of rice straw fed as 50% of the diet improved gains over the diet containing 50% URS, but no significant influence on animal performance was observed when rice straw was fed at the 25% level. Each 10% addition of URS to basal diet decreased empty body gain of steers by 116 gram per day compared with a decrease of 70 gram per day when rice straw had been ammoniated. There was no beneficial effect of ammoniation when the roughage component of the diet was a 50:50 mixture of rice straw and alfalfa. Ammoniation of straw and inclusion of alfalfa generally increased the concentration of total volatile fatty acids in rumen fluid. Ammoniation resulted in reduced concentrations of acetic and propionic acid, but increased concentration of butyric acid. Digestibility of URS was improved by mixing with alfalfa. However, alfalfa hay did not influence digestibility of ARS. Diets in which ARS replaced the basal mixture at 25 and 50% had higher NEm and NEg values than comparable URS diets. The same pattern was observed in the straw: alfalfa mixtures, but differences between URS and ARS were significant only for the 50% roughage diets.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.70-77
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• 2010

This study is to investigate experimentally the influence of mixing factors, such as a mortar mix proportion of non-cement mortar, flow, and W/B, on quality characteristics of blast furnace slag powder mortar incorporating dry type recycled fine aggregates. In the characteristics of fresh mortar, the W/B increased according to the increase in the flow due to the increase in water contents, but air contents decreased due to loss of air contrary to the increase in the W/B. In the case of hardened mortar, the compressive strength showed a decrease due to the highly determined W/B inversely according to the increase in the flow through the entire age in which the compressive strength increased proportionally according to the increase in the B/W. Also, the increasing rate of such compressive strength increased more largely due to the latent hydraulic property of the BS according to the passage of the age. The flexural strength at the age of 28 days according to the increase in the B/W represented a similar level in strength values without any increases. The flexural strength for the compressive strength was distributed as a range of 1/2 ~ 1/3 and that showed a higher range than that of conventional concretes.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.113-119
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• 2009

This study is to investigate the fundamental and fireproof qualities of high strength concrete corresponding to changes in the curing factors and the PP fiber ratio. The results were as follows. For the fundamental characteristics of concrete, the fluidity was reduced in proportion to the increase in the PP fiber ratio. The compressive strength was somewhat reduced according to an increase in the PP fiber ratio. However, it had the high strength scope of more than 60 MPa at 7 days and of more than 90 MPa at 28 days. On the spalling mechanism followed by changes of the water content ratio, spalling was prevented in all combinations, except the specimen without PP fiber and subjected to 3.0% of moisture contents. When spalling was prevented at that time, the residual compressive strength ratio was 22%~41% and the mass reduction ratio was 5%~7%, which was relatively favorable. As the spalling mechanism corresponds to changes in the curing method, spalling was prevented in concrete with a PP fiber mixing ratio of more than 0.05% in the event of standard curing, and in concrete with a PP fiber mixing ratio of more than 0.10% in the case of steam curing and autoclave curing. In these cases, when spalling was prevented, the residual compressive strength ratio was 23~42% and the mass reduction ratio was 7~11%. In these results, the ease of spalling prevention in high strength concrete was inversely proportional to the water content ratio. Depending on the curing method, spalling was prevented in concrete with over 0.05% PP fiber with standard curing and in concrete with over 0.1% PP fiber with steam curing and autoclave curing.