• 한국주조공학회지
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• 제37권5호
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• pp.148-156
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• 2017

The effects of minor additives on the casting properties of AC4A aluminum alloys were investigated. Measurements of the cooling curve and microstructure observations were conducted to analyze the effects of Ti-B and Sr minor elements during the solidification process. A fine grain size and an increase in the crystallization temperature for the ${\alpha}-Al$ solution were evident after the addition of 0.1wt% Al-5%Ti-1%B additive. The modification effect of the eutectic $Mg_2Si$ phase with the addition of 0.05% Al-10%Sr additive was prominent. A fine eutectic $Mg_2Si$ phase and a decrease in the growth temperature of the eutectic $Mg_2Si$ phase were evident. Fluidity, shrinkage and solidification-cracking tests were conducted to evaluate the castability of the alloy. The combined addition of Al-5%Ti-1%B and Al-10%Sr additives showed the maximum filling length owing to the effect of the fine ${\alpha}-Al$ grains. The macro-shrinkage ratio increased, while the micro-shrinkage ratio decreased with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives. The macro-shrinkage ratio was nearly identical, while the micro-shrinkage ratio increased with the addition of the Al-10%Sr additive. The tendency of the occurrence of solidification cracking decreased owing to the effect of the fine ${\alpha}-Al$ grains and the modification of the $Mg_2Si$ phase with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives.

• 농업과학연구
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• 제15권1호
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• pp.82-94
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• 1988

이 논문(論文)은 기포(起泡)모르터의 제특성(諸特性)에 관(關)한 기초자료(基礎資料)를 제공(提供)하고져 수행(遂行)되었는 바, 이 연구(硏究)를 통(通)하여 얻어진 결과(結果)를 요약(要約)하면 다음과 같다. 1. 각(各) 기포(氣泡)모르터에서 물-시멘트비는 당배합비(富配合比)일수록, 기포제(起泡劑) 및 기포(氣泡)의 첨가량(添加量)이 증가(增加)할수록 감소(減少)하였으며, 보통(普通)시멘트 모르터에 비(比)하여 혼합기포주입형(混合氣泡注入型)은 1.6~53.1%, 사전기포주입형(事前氣泡注入型)은 4.4~24.1%의 물-시멘트비(比)가 감소(減少)되었다. 2. 각(各) 기포(氣泡)모르터의 밀도(密度)는 빈배합(貧配合)일수록, 기포제(起泡劑) 및 기포(氣泡)의 첨가량(添加量)이 증가(增加)할수록 작게 나타났으며, 밀도(密度)의 감소율(減少率)은 당배합(富配合)일수록, 기포제(起泡劑) 및 기포(氣泡)의 첨가량(添加量)이 증가(增加)할수록 크게 나타났다. 3. 기포(起泡)모르터는 보통(普通)시멘트 모르터에 비(比)하여 혼합기포주입형(混合氣泡注入型)은 38.8~55.9%, 사전기포주입형(事前氣泡注入型)은 9.7~23.6%의 자중감소(自重減少)를 보였다. 4. 각(各) 기포(起泡)모르터의 급수율(吸水率)은 빈배합(貧配合)일수록, 기포제(起泡劑) 및 기포(氣泡)의 첨가량(添加量)이 증가(增加)할수록 높게 나타났으며, 흡수율(吸水率)의 증가율(增加率)은 당배합(富配合)일수록, 기포제(起泡劑) 및 기포(氣泡)의 첨가량(添加量)이 증가(增加)할수록 크게 나타났다. 5. 72시간(時間) 수침(水浸)에서 각(各) 기포(氣泡)모르터의 흡수율(吸水率)은 보통(普遇)시멘트 모르터에 비(比)하여 혼합기포주입형(混合氣泡注入型)은 3.41~5.85배(倍)로 나타났으며, 사전기포주입형(事前氣泡注入型)은 1.05~1.55배(倍)로 나타났으며, 흡수율(吸水率)의 변화율(變化率)은 모두 수침초기(水浸初期)에 높게 나타나는 경향(傾向)을 보였다. 6. 각(各) 기포(氣泡)모르터의 각(各) 강도(强度)는 빈배합(貧配合)일수록, 기포제(起泡劑) 및 기포(氣泡)의 첨가량(添加量)이 증가(增加)할수록 작게 나타났으며, 각(各) 강도(强度)의 감소율(減少率)은 빈배합(貧配合)일수록, 기포제(起泡劑)나 기포(氣泡)의 첨가량(添加量)이 증가(增加)할수록 크게 나타났다. 7. 기포(氣泡)모르터는 보통(普通)시멘트 모르터에 비(比)하여 재령(材齡) 28일(日)에서 혼합기포주입형(混合氣泡注入型)은 77.0~92.8%, 사전기포주입형(事前氣泡注入型)은 36.7~74.4%의 강도감소(强度減少)를 보였고, 각(各) 기포(氣泡)모르터의 각(各) 강도간(强度間)의 상관관계(相關關係)는 직선형(直線形)으로 나타났으며 고도(高度)의 유의성(有意性)이 인정(認定)되었다. 8. 각(各) 기포(氣泡)모르터의 공기량(空氣量)은 빈배합(貧配合)일수록, 기포제(起泡劑)나 기포(氣泡)의 첨가량(添加量)이 증가(增加)할수록 크게 나타났으며, 공기량(空氣量)이 증가율(增加率)은 당배합(富配合)일수록, 기포제(起泡劑)나 기포(氣泡)의 첨가량(添加量)이 증가(增加)할수록 높게 나타났다. 9. 기포(氣泡)모르터의 공기량(空氣量)은 보통(普通)시멘트 모르터에 비(比)하여 혼합기포주입형(混合氣泡注入型)은 26.0~63.8배(倍), 사전기포주입형(事前氣泡注入型)은 5.8~17.7배(倍)를 보였다. 10. 각(各) 기포(氣泡)모르터에서 밀도(密度)와 흡수율(吸水率), 압축강도(壓縮强度) 및 공기량(空氣量)과의 상관관계(相關關係)는 매우 높은 유의성(有意性)을 보였고, 배합비(配合比)와 기포제(起泡劑) 및 기포(氣泡)의 첨가량(添加量)에 따라 밀도(密度), 흡수율(吸水率), 제강도(諸强度) 및 공기량(空氣量)을 추정(推定)할 수 있는 다중회귀방정식(多重回歸方程式)을 유도(誘導)하였으며 각(各) 방정식(方程式)은 고도(高度)의 유의성(有意性)이 인정(認定)되었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.157-160
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• 2006

Recently, trouble of sand supply is occurred according to exhaustion of natural sand resources. To solve this problem, sea sand and crushed sand are used. But, necessity of water reducing agent because quality of concrete that use sea sand and crushed sand is deteriorated. Therefore in this study was examined on the engineering properties of concrete with kind of fine aggregate and addition ratio of water reducing agents. As a result, compressive strength appeared similar standard regardless of kind of fine aggregate. Compressive strength, durability was similar in decrease of the unit water content by increase of addition ratio of the water reducing agent. Also, drying shrinkage resistivity was improved because the unit water content decreased.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.34-35
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• 2016

Most of the construction adhesive may contain harmful component to the human body with an organic adhesive. In addition, when the adhesive caused hydroquinone, alkyl benzophenone, etc, also it raises the skin diseases to workers. Therefore, the inorganic adhesive development is necessary. This study was a study to know adhesive strength properties that adhesive using a magnesium oxide according to the addition ratio of the retarder. It has experiments to two types of magnesium oxide and type and ratio of retarder differently.

• 미생물학회지
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• 제7권2호
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• pp.86-90
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• 1969

1. Amylase producing bacteria have been isolated from natural sources and was identified out. The above strain is identical to Bacillus subtillis in every details of physiological and morphorogical characteristics by this investigations. 2. Sikworm chrysalis nad chlorella extracts are prove to be further effective for the stimulation of amylase production than any other sources. The former silkworm extract is more stronger in its activity. 3. It is found that effective results had been accepted by a less soybean meal addition per that of wheat bran in the mixture ratio of them, also less addition of corn is needed in the mixture ratio of between corn and whear bran. In the mixing ratio of wheat bran per silkworm or chlorella extracts, the addition of wheat bran is necessary for stimulation of amylase production. 4. Fro the stimulation of amylase production, the effective substances from natural sources and its order of activity in cultral media cultral media is proved as follows, silkworms ext.>chlorella ext.>alcohol>skim-milk and peptone>fermented milk>radish leaf ext.

• 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%.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.114-120
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• 2006

The basic effects of hydrogen addition for engine performance and emission were investigated in single cylinder research engine. Seven commercial injectors were tested to choose a suitable injector for hydrogen injection prior to its engine implementation. The hydrogen fuel leakage and flow rate were evaluated for each injector and KN3-1(Keihin, CO.) showed the best performance for hydrogen fuel. At the higher excess air ratio(${\lambda}=1.7$, 2.0), the better combustion stability was found with hydrogen addition even though its effect was small at lower excess air ratio (${\lambda}=1.0$, 1.3). Stable operation of the engine was even guaranteed at ${\lambda}=2.0$, if the amount of hydrogen gas was near 15% of total energy. In the lean region, ${\lambda}>1.3$, thermal efficiency was improved slightly while it was not clearly observed at ${\lambda}=1.0$, 1.3. It is considered that, in some cases, high temperature environment due to hydrogen combustion caused further heat loss to surroundings. Except for ${\lambda}=1.0$, with larger amount of hydrogen addition, CO was reduced drastically but it was emitted more at the leaner region. Nitric oxides(NOx) was increased a little more with hydrogen addition at ${\lambda}=1.0$, 1.3. However, at ${\lambda}>1.3$ its relative amount of emission was low. In addition, the amount of NOx was continuously decreased with hydrogen addition, but, at ${\lambda}=2.0$ the amount of NOx was lowered to 1/100 of that of ${\lambda}=1.0$. THC emission was significantly increased as air/fuel ratio was raised to leaner region due to misfire and partial burn.

• Journal of Advanced Marine Engineering and Technology
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• 제7권2호
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• pp.15-21
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• 1983

Preparing for treatment and management of the emulsified fuel oil which will be generalized henceforth, this paper is an attempt to examine the viscosity-temperature characteristics of emulsified heavy fuel oil which is mixed with water and emulsifier in various mixture ratio by mechanical mixer. The experimental results are summarized as follows: 1. The viscosity-temperature characteristics of the emulsified C & B grade heavy fuel oil mixed with water of same or less weight, is changed according to log.log(v+0.6)=b-3.8log T. 2. The emulsifier has to be added to the emulsified A grade heavy fuel oil mixed with water of same or less weight, because it is instable. Especially if the emulsifier is sodium stearate, it is added more than 0.3% of the weight of oil and water. 3. In the emulsified A grade heavy fuel oil mixed with water and emulsifier, the higher the ratio of water addition becomes, the higher the viscosity is and the more the viscosity-temperature slope decreases. But the higher the ratio of emulsifier addition is, the more the viscosity-temperature slope increases. In this case, the linearity of viscosity-temperature characteristic curve is poorer than that of B and C grade heavy fuel oil. 4. In the emulsified A grade heavy fuel oil mixed with emulsifier of 0.3% or less, the emulsion type is O/W type when water addition ratio is 40%, but it is W/O type when it is 10%, 20%, 30% and 50%.

• 한국식품영양학회지
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• 제21권4호
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• pp.436-442
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• 2008

Buckwheat leaves and young parts of the plant are consumed as a vegetable in certain countries. The quality characteristics of Sulgidduk withadded buckwheat vegetable powder(BVP)(0, 0.2, 0.5, 1.0, 1.5% w/w) were assessed in this study. Weobtained the following results: The water contents of Sulgidduk on the first day evidenced no differences according to the ratio of BVP addition, whereas the water contents of Sulgidduk decreased with increasing storage time and increasing amounts of added BVP. As the amount of BVP increased, both the L value(Lightness) and the a value(Redness) decreased, whereas the b value(Yellowness) increased. In terms of the mechanical texture characteristics, the hardness of the Sulgidduk increased with addition of both 0% and 0.5% BVP, with increases in storage time. The springiness of Sulgidduk was reduced as the quantities of BVP increased. We detected no significant differences in the chewiness of Sulgidduk according to the ratio of BVP addition. Also, the chewiness of Sulgidduk increased with BVP additions of 0% and 0.2% with increases in storage time, whereas no differences were detected in the group to which 0.5% BVP was added. The cohesiveness of the Sulgidduk decreased with increases in BVP and storage time. In our sensory evaluation of the color and flavor characteristics, the optimal quality was reported in conjunction with the Sulgidduk to which 1.0% and 1.5% BVP was added(p<0.05), whereas we noted no significant differences in texture and taste(sweetness) according to the ratio of BVP addition. Sulgidduk with 1% of BVP evidenced the best characteristics in our overall sensory evaluation.

• 한국건설순환자원학회논문집
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• 제5권3호
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• pp.55-62
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• 2010

오늘날 각종폐기물 발생량이 증가되는데, 본 실험 연구에서는 미장 및 벽돌 제조용의 배합비를 적용하여 시멘트 모르타르의 하수슬러지 소각재의 폐기물을 이용하여 활용가능성에 대한 기초적 자료를 제시함이 본 연구의 목적이다. 실험에 따른 결과를 종합해 볼 때, 배합비 1:2의 하수슬러지 10%와 황토의 소량 첨가율과 배합비 1:7의 경우 압축강도가 다소 작지만 석분과 하수슬러지 10% ~ 20%를 첨가하면 하수슬러지를 재순환 할 수 있으며, 환경 친화적인 재료의 기초적 자료로 활용 가능할 것으로 판단된다.