• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.169-170
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• 2015

This study is the experiment for manufacturing the Lightweight non-cement matrix based on the blast furnace slag, paper ash. Materials like cement and blowing agent in foamed concrete is replaced by by-products fro blast furnace slag and paper ash. Further, the experiment was performed by replacing alkali with nature gypsum and α type gypsum by (0, 5, 10, 15, 20) of weight of alkali (wt.%) in order to reduce the amount of expensive alkali-activator. Consequently, in the case of the density, plain showed the lowest density and it seems that specimen adding nature gypsum 5% has the best compressive strength and flexural strength. It is detemined that the strength is lowered in accordance with the α type gypsum replacement ratio is higher. The research that it can supplement the further intensity seems to be needed.

• Architectural research
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• 제26권1호
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• pp.13-20
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• 2024

This study is a research investigation into the properties of bubbles that affect the characteristics of foamed concrete during its production. The study examined the properties of bubbles based on the manufacturing conditions. To investigate these properties, the selected experimental factors included bead size, the length/diameter ratio of the bubble-generating tube, and compressed air. The experimental design used a design of experiments, and the test results were analyzed using analysis of variance. The foaming agent used to generate bubbles was AES (Alcohol Ethoxy Sulfate), and the method employed for bubble manufacture was the pre-foaming method. In the test results, a significant factor affecting the foaming rate of bubbles was the bead size; the highest foaming rate was observed when using 2mm beads. Bead size also primarily influenced the volume change of the aqueous solution, while other factors did not affect the foaming rate and volume change. None of the factors affected the change in bubble size, but compressed air was considered the main factor affecting bubble size and its change. The foaming rate and volume change of the aqueous solution showed a high correlation with each other. Spherical bubbles in the early stage eventually transformed into angular bubbles. Moreover, over time, it was observed that the bubble size increased.

• KIEAE Journal
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• 제10권3호
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• pp.89-96
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• 2010

In comparison with ordinary or heavy-weight concrete, light-weight air void concrete has the good aspects in optimizing super tall structure systems for the process of design considering wind load and seismic load by lightening total dead load of buildings and reducing natural resources used. Light-weight air void concrete has excellent properties of heat and sound insulating due to its high amount porosity of air voids. So, it has been used as partition walls and the floor of Ondol which is the traditional Korean floor heating system. Under the condition of which the supply of light-weight aggregates are limited, the development of light-weight concrete using air voids is highly required in the aspects of reduced manufacturing prices and mass production. In this study, we investigated the physical properties and thermal behaviors of specimens that applied different mixing ratios of foaming agent to evaluate the possibility of use in the structural elements. We proposed the estimating equation for compressive strength of each mix having different ratio of foaming agent. We also confirmed that the density of cement matrix is decreased as the mixing amount of foaming agent increase up to 0.6% of foaming agent mixing ratio which was observed by SEM. Based on porosity and compressive strength of control mortar without foaming agent, we built the estimating equations of compressive strength for mortars with foaming agent. The upper limit of use in foaming agent is about 0.6% of the binder amount. Each air void is independent, and size of voids range from 50 to $100{\mu}m$.

• 한국농공학회지
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• 제27권1호
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• pp.46-61
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• 1985

This study was performed to obtain the basic data which can be applied to the use of foaming mortars. The data was based on the properties of foaming mortars depending upon various mixing ratios and addings to compare those of cement mortar. The foaming agents which was used at this experiment were pre-foamed type and mix-foaming type which is being used as mortar structures. The foaming mortar, mixing ratios of cement to fine aggregate were 1:1, 1: 2, 1 : 3 and 1 : 4. The addings of foaming agents were 0.0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5% and 3.0% of cement weight. The results obtained were summarized as follows; 1. At the mixing ratio of 1 : 1, the lowest water-cement ratios were showed by foaming mortars, respectively. But it gradually was increased in poorer mixing ratio and decreased in more addition of foaming agent. The water-cement ratios were decreased up to 1. 8~22. 0% by G, 2. 2~24. 1 % by U and 0. 7~53. 1% by J foaming mortar than cement mortar. 2, At the mixing ratio of 1 : 1, the highest bulk densities were showed by foaming mortars, respectively. But, it gradually was decreased in poorer mixing ratio and more addition of foaming agent. The bulk densities were decreased up to 1. 4~20. 7% by G, 2. 3~23. 7% by U and 26. 5~56. 5% by J foaming mortar than cement mortar. Therefore, foaming mortar could be utilized to the constructions which need low strengths. 3. At the mixing ratio of 1:1, the lowest absorption rates were showed by foaming mortars, respectively. But, it gradually was increased in poorer mixing ratio and more addition of foaming agent. Specially, according to the absorption rate when immersed in 72 hours, the absorption rates were showed up to 1. 01~1. 24 times by G, 1. 03~1. 58 times by U and 1. 10~5. 91 times by J foaming mortar than cement mortar. It was significantly higher at the early stage of immersed time than cement mortar. 4. At the mixing ratio of 1:1, the lowest air contents were showed by foaming mortars, respectively. But, it gradually was increased in poorer mixing ratio and more addition of foaming agent. Air contents were contented up to 4. 0~17. 2 times by G, 5. 2~23. 2 times by U and 23. 8~74. 5 times by J foaming mortar than cement mortar. 5. At the mixing ratio of 1 : 1, the lowest decreasing rates of strengths were showed by foaming mortars, respectively. But, it gradually was increased in poorer mixing ratio and more addition of foaming agent. Specially, the strengths of 28 days were decreased 0. 4~2. 2% than those of 7 days by foaming mortar, respectively. Also, the correlations between compressive and tensile strength, compressive and ending strength, tensile and bending strength were highly significant as a straight line shaped, respectively. 6. The correlations between absorption rate, air content, compressive strength and bulk density, absorption rate, compressive strength and air content were highly significant, respectively. The multiple regression equations of water-cement ratio, bulk density, absorption ate, air content, compressive strength, tensile strength and bending strength were computed depending on a function of mixing ratio and addition of foaming agent. It was highly significant, respectively. 7. At the mixing ratio of 1 : 1, the highest strengths were showed by cement mortar and foaming mortars, by chemical reagents. But, it gradually was decreased in poorer mixing ratio. The decreasing rates of strengths were in order of H $_2$S0 $_4$, HNO$_3$ and HCI, J,U,G foaming mortar and cement mortar. Specially, at the each mixing ratio, each chemical reagent and 3.0% of foaming agent, J foaming mortar was collapsed obviously. Therefore, for the structures requiring acid resistence, adding of foaming agent should be lower than 3.0%.

• 한국재료학회지
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• 제29권10호
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• pp.617-622
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• 2019

In order to develop a process for manufacturing a composite structure of an intermetallic compound foam and a hollow material, the firing and pore form of the Al-Ni precursor in a steel pipe are investigated. When the Al-Ni precursor is foamed in a hollow pipe, if the temperature distribution inside the precursor is uneven, the pore shape distribution becomes uneven. In free foaming, no anisotropy is observed in the foaming direction and the pore shape is isotropic. However, in the hollow pipe, the pipe expands in the pipe axis direction and fills the pipe. The interfacial adhesion between $Al_3Ni$ foam and steel pipe is excellent, and interfacial pore and reaction layer are not observed by SEM. In free foaming, the porosity is 90 %, but it decreases to about 80 % in the foam in the pipe. In the pipe foaming, most of the pore shape appears elongated in the pipe direction in the vicinity of the pipe, and this tendency is more remarkable when the inside pipe diameter is small. It can be seen that the pore size of the foam sample in the pipe is larger than that of free foam, because coarse pores remain after solidification of the foam because the shape of the foam is supported by the pipe. The vertical/horizontal length ratio expands along the pipe axis direction by foaming in the pipe, and therefore circularity is reduced.

• 한국지반신소재학회논문집
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• 제17권2호
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• pp.41-49
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• 2018

본 연구에서는 준설토 활용을 촉진하고 지반개량을 최소화 하기위한 목적으로 연약지반에서 경량기포혼합토를 토공재료로 이용하여 실규모의 도로 성토체를 제작하고 그 재료특성과 거동을 분석하였다. 현장에서 배합된 시료의 실내시험 결과 공시체의 습윤단위중량은 양생 28일까지 거의 선형적으로 감소하였고, 특히 28일 양생 후 습윤단위중량은 양생 전 슬러리 상태의 약 81%로 감소되었으므로 향후 유사한 원료토의 배합설계시 활용이 가능하다. 일축압축강도는 기존의 연구와 같이 양생 14일을 기준으로 강도증가율이 감소하기 시작하였고, 시멘트 함유량이 많아질 경우 최대 압축강도 발생 후 적은 변형률 변화에서 강도가 급격히 감소하며, 통상보다 작은 축변형률 범위에서 최대강도가 발현되는 현상이 나타났다. 경량성토로 인한 원지반 천층부에서의 침하량은 토사성토의 약 1/2.75로서 성토재료의 단위중량 비율(1/2.7)과 일치함으로써 자중의 차이로 인한 침하량의 인과관계가 잘 나타났다. 또한 원지반 하부로 내려갈수록 토사 및 경량성토 사이의 침하량 차이가 크게 나타남으로써 침하종료 심도에 차이가 명확하게 나타났다. 경량성토 구간의 지중수평변위량은 토사성토 대비 약 15~20% 정도 작게 나타났고, 그 발생심도 또한 경량성토의 경우가 4.5~5.0m 가량 얕게 나타나 경량기포혼합토가 전단변형의 영향심도를 현저히 감소시키는 효과가 있음을 확인하였다.

• 폴리머
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• 제29권6호
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• pp.605-612
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• 2005

폴리올레핀계 공중합체 수지인 polypropylene-polyethylene-(1-butene) 미발포 수지에 부탄 가스를 물리적 발포제로 이용하여 단열 팽창시킨 발포체의 등온 결정화 거동을 DSC(differential scanning calorimeter)와 편광 현미경을 이용하여 고찰하였으며, 얻어진 결과는 Avrami 식을 이용하여 해석하였다. 발포체의 결정화 반감 시간이 미발포체의 결정화 반감 시간보다 짧고 핵 생성 속도 증가에 따른 nucleation density증가 및 구정 성장 속도가 더 빠름이 발견되었는데, 이는 가공 공정 중의 분자량 감소보다는 단열 팽창 과정에서 진행되는 연신 배향 결정화에 의해 결정화 속도가 증가하였기 때문인 것으로 사료된다. 또한, 단열 구조 발포체는 직경 30 $\mu$m 이하의 균일한 closed cell 형태를 나타내고 있음을 SEM 을 이용하여 관찰하였고, 발포체의 물성은 미발포체에 비해 단열성이 크기 때문에 열전도도가 감소하였고 압축강도는 발포비가 증가할수록 감소하는 것을 알 수 있었다.

• 한국산학기술학회논문지
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• 제19권8호
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• pp.562-570
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• 2018

고분자 단독으로는 얻을 수 없는 다양한 물성을 얻기 위하여 두 가지 이상의 고분자를 블렌드하는 기법을 많이 사용하고 있다. 폴리올레핀계 TPE(Thermoplastic Elastomer)는 디스플레이, 자동차, 가전제품 등에 널리 사용되고 있다. 소비자는 고감성이고 고급화된 자동차 내장부품을 요구한다. 높은 폼형성도와 흐름성이 있는 고분자소재 개발이 필요하다. 내부에 폼층이 있는 TPE은 좋은 고분자소재이다. 두 종류의 TPE 소재를 개발하였다. 첫번째 소재는 Homo-PP(PolyPropylelne)에 SEBS/Oil을 혼합하였고, 두 번째 소재는 Co-PP와 SEBS/Oil을 혼합하였다. 혼합온도는 $180^{\circ}C$, $190^{\circ}C$. $260^{\circ}C$(두번째 소재), 혼합속도는 50rpm, 혼합시간은 5분이다. TPE의 MI(Melt Index)는 PP의 MI에 영향이 있고, 혼합온도의 영향은 미미하였다. 경도와 인장탄성률은 PP의 MI와 혼합온도의 영향은 적었으나, SEBS/Oil의 비율이 높아지면 낮아졌다. 소프트터치감은 SEBS/Oil의 비율이 증가하면 증대하였다. TPE릉 자일렌으로 SEBS/Oil 층을 녹여내어 IPN(Interpenentration polymer network) 구조를 확인할 수 있었으며, Strain-harding 현상도 확인하였다. 제조한 TPE가 고무현상을 보이고, 생성된 closed cell이 안정한 상태임을 알 수 있다.

• 한국산업융합학회 논문집
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• 제23권6_2호
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• pp.1067-1074
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• 2020

Green houses provide a more conditioned and warmer environment than the outside environment due to insulation. Currently used insulation materials include soft film (PVC, PE, EVA), foamed PE sheet, non-woven fabric, reflective film, and multi-layer insulation curtain, but there are many disadvantages and to compensate for this, silica aerogel insulation material with excellent warmth, light weight, and small volume Research using is in progress. In this study, the temperature change of the quadruple-structure green house and the temperature change in the dual-structure green house of soft film and silica airgel were investigated. The daytime temperature change was highest in A and A2 (soft film) at 10 to 16:00 after sunrise, but showed the lowest temperature at 17 to 18:00, which is the sunset time, showing the greatest change. The airgels of D and D2 showed the smallest change in temperature after sunrise and right after sunset. That is, it can be said that the airgel is hardly affected by external temperature. The temperature change at night was highest in D and D2 (aerogel) for both quadruple and dual structures. The temperature at night was measured higher in the quadruple structure than in the double structure. As for the ratio of the internal temperature to the external temperature for the quadruple structure and the double structure, D (aerogel) was not affected by the external temperature during the day in the quadruple structure and the double structure. D (Aerogel) seems to be able to reduce the damage caused by high temperatures in summer due to the high thermal insulation effect of the airgel, as the temperature rises above 4℃ at night. And in winter, it helps to save heating costs due to less heat emitted to the outside.

• 농업과학연구
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• 제42권1호
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• pp.37-46
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• 2015

This study was carried out to determine the effect of storage condition, such as temperature and relative humidity (RH), on the change of sensory properties and free fatty acid composition of pre-packed Hanwoo loin (Musculus longissimus) until $21^{st}$ day of storage. The Hanwoo loin was sliced in $1.0{\pm}0.2cm$ thickness and each of the sliced pieces was packed in a foamed polystyrene tray with linear low-density polyethylene (LLD-PE) film to simulate the pre-packed Hanwoo loin sold in retail market, then stored in home-style refrigerator (Con; $5^{\circ}C$, 17%RH), and temperature and RH controled chambers (T1; $5^{\circ}C$, 55%RH, T2; $5^{\circ}C$, 85%RH, and T3; $-1^{\circ}C$, 99%RH), respectively. The sensory characteristics of pre-packed Hanwoo loin during storage in different conditions were measured on raw or after cooking. After 21 days of storage, the loin stored in T3 showed significantly high color and acceptability scores ($7.46{\pm}1.07$, $7.06{\pm}1.36$, respectively) on raw loin, and flavor and acceptability scores ($7.16{\pm}0.90$, $6.90{\pm}0.92$, respectively) on cooked loin than those of others (p<0.05). The concentration of 12 fatty acids of pre-packed Hanwoo loin during storage in different conditions were analysed. The concentration of oleic acid (C18:1, $39.92{\pm}3.22%$), palmitic acid (C16:0, $28.20{\pm}2.42%$), and stearic acid (C18:0, $12.59{\pm}2.79%$) was high in Hanwoo loin on $1^{st}$ day of storage. The concentration of palmitic acid of Hanwoo loin stored in T2 was increased significantly after $4^{th}$ day of storage (p<0.05), and the concentration of myristic acid(C14:0) of Hanwoo loin stored in treated chamber (T1 to T3) was significantly higher than Con after $14^{th}$ day of storage (p<0.05). The concentration of linolenic acid (C18:3) of Hanwoo loin was decreased significantly after $4^{th}$ day of storage in all tested storage conditions (p<0.05). However, there was no significant or consistent change in the concentration of oleic acid (C18:1) during storage period in every Hanwoo loin stored in tested conditions. Although, the concentration of total monounsaturated fatty acids (MUFA) was decreased in Con and T2 (p<0.05), there was no consistent change in the monounsaturated fatty acids to saturated fatty acids ratio (MUFA/SFA) during storage period (p>0.05). From those results, it was considered that storage condition affects on the sensory acceptability and fatty acid composition of pre-packed Hanwoo loin as storage period was increased.