• 한국농공학회논문집
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• 제46권1호
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• pp.35-40
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• 2004

This study is performed to examine the physical and mechanical properties of eco-concrete using soil, natural coarse aggregate, excellent soil compound and polypropylene fiber. The test result shows that mass loss ratio is decreased with increasing the content of coarse aggregate and excellent soil compound. The compressive and flexural strengths are increased with increasing the content of coarse aggregate, excellent soil compound and polypropylene fiber. The coefficient of permeability is decreased with increasing the content of coarse aggregate and excellent soil compound, but it is increased in 0.2% polypropylene fiber content. The lowest coefficient of permeability is showed in $5.066\times 10^{-9}$cm/s. These eco-concrete can be used for farm road.

• 한국주조공학회지
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• 제31권3호
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• pp.130-136
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• 2011

Effects of GBF (gas bubbling filtration) treatment conditions and scrap ratio on the electric conductivity of a commercial pure aluminum for diecasting were investigated using by specific gravity and electrical conductivity measurement system, hydrogen gas analyzer, XRD, and EDS. Electrical conductivities of specimen mixed Al scrap ratio until 60% from 0% were decreased with increasing the precipitates amount and size of AlFeSi ternary intermetallic compound on the grain boundary as well as amount of porosity in the grain. On the other hand, electrical conductivities was reincreased gradually in spite of scrap ratio increase from 80% to 100%. Size of AlFeSi compound formed on the grain boundary were coarsened with the increament of scrap ratios untill 80% and GBF treatment time simultaneously.

• 한국식품영양학회지
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• 제36권5호
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• pp.354-359
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• 2023

A mono-type glycerine fatty acid ester compound was chemically synthesized using medium-chain fatty acids with antibacterial activity, and the physicochemical quality and antibacterial activity of the synthesized glycerine medium-chain fatty acid ester compound were measured. At a reaction molar ratio of MCT(medium chain triglyceride) to glycerine of 1:2.5, 48.15% mono ester was produced. The physicochemical analysis of the synthesized glycerine fatty acid ester compound showed an acid content of 0.38~0.60%, which tended to increase slightly as the glycerine molar ratio increased. The saponification value decreased as the synthesized molar ratio of glycerine increased from 218 to 284. The number of bacteria was measured to confirm the degree of antibacterial activity of glycerine medium-chain fatty acid esters against food poisoning bacteria, Bacillus cereus and Salmonella typhi. The number of bacteria significantly decreased as the MCT:glycerine molar ratio increased. In particular, the antibacterial effect between the treatment groups was the highest when at an MCT:glycerine molar ratio of 1:2.5.

• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.100-105
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• 2012

In previous study, to investigate the impression of the compound lighting based on the AC-Model at the full-size room, the impressions of various compound lighting were completed as compared with that of the uniform lightings through the comparison method (a paired comparison) by Semantic Differential scaling. Also, we examined the effect of the supplementary lighting type increasing the lights at the side of the window and the blind-control lighting type, and they were compared with the existing compound lighting type. In results, pared comparison of the compound lighting and the uniform lighting, indicates that the impression of the compound lighting is generally similar to that of the uniform lighting when there are same ratios of the light from the window. Based on these results, we suggest that the AC-Model might be applied to various conditions. And we also introduce the method for daylighting that it is possible to reduce discomfort glare and to improve visual impressions as the supplementary type and blind-control type on the compound lighting. And it was found that electric power consumption of the compound lighting room was lower than that of the uniform lighting room when as same lighting ratio of the compound lighting and the uniform lighting from the window was provided or there was the lighting distribution simulated to same light ratio from the window. Since the method of the ACModel was described in the experimental condition, additional studies should be performed to determine if this model could be applied to different window configurations, lighting layout and types of a room.

• Journal of Mechanical Science and Technology
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• 제16권9호
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• pp.1137-1146
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• 2002

An experiment has been conducted on the flow and heat transfer characteristics of film coolant injected from a row of five holes with compound angle orientations of 35$^{\circ}$ inclination angle and 45$^{\circ}$ orientation angle. The Reynolds number based on the mainstream velocity and injection hole diameter 3.58${\times}$10$^4$. Three-dimensional velocity, film cooling effectiveness and heat transfer coefficient data are presented at three different mass flux ratios of 0.5, 1.0 and 2.0. Flow entrainment has been found between the vortices generated by adjacent injectants. The injectant with compound angle orientation entrains not only the mainstream boundary layer flow but also the adjacent injectant. Because of the flow entrainment, the injectant. With compound angle orientation is characterized by a single vortex while two bound vortices are usually observed in the case of simple angle injection. The strength of the secondary flow depends strongly on the mass flux ratio, which shows significant influence on the film cooling effectiveness and heat transfer coefficient.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2004년도 학술대회지
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• pp.33-38
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• 2004

This study was performed to know watertightness and reduction effect and crack occurred by hydration heat, restraint of multiplication of hydration heat, through mechanical test, strength test and crack control test using fluosilicate salt based inorganic compound made from by-product during phosphoric acid manufacturing process. Mix proportions for experiment were modulated at 0.45 of water to cement ratio and $0.5-2.0\%$ of adding ratio of fluosilicate salt based inorganic compound. Evaluation for watertightness of concrete was carried out permeability, absorption test and porosity analysis. Effect of crack reduction was evaluated by length, drying shrinkage as well as stress change of hardened concrete at unrestraint/restraint state and also elucidated crack pattern on the concrete surface. It is ascertained that characteristics of crack resistance and watertightness for concrete was improved by an adequate addition of fluosilicate salt based inorganic compound.

• 한국염색가공학회지
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• 제32권4호
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• pp.245-254
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• 2020

The sheet molding compound composite has been applied divers section. This paper reports processing of carbon fiber reinforced thermosetting composite with diverse resins and which was composed of chopped carbon fiber (30 ~ 60 wt%). Normally the paste that the viscosity is over 15,000 cps has been used in traditional Sheet molding compound (SMC) machine. In this research, SMC machine was designed to make Carbon-sheet molding compound (C-SMC) prepreg which was composed with low viscosity resin (1,800 ~ 2,500 cps increase up to 10,000 cps after aging). In order to confirm the optimal processing condition. Mechanical strength tests including tensile test, shear test, impact test, flexural strength test were conducted on C-SMC composites. Plus we identified the correlation between the mechanical properties and prepreg processing condition (carbon ratio and applied resin).

• 한국산림과학회지
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• 제18권1호
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• pp.1-7
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• 1973

본시험(本試驗)은 리기다소나무 인공단순림(인공단순림)에 있어서 임분재적추정(林分材積推定)을 단급법(單級法) 단순임의추출법(單純任意抽出法) 복합비추정법(複合比推定法) 분리비추정법(分離比推定法) 표준목비추정법(標準木比推定法)등의 방법(方法)으로 조사비교(調査比較)한 것이다. 비추정(比推定)에 의하여 얻은 결과(結果)는 표(表) 8과 같아 실제임분재적(實際林分材積)이 추정임분재적내(推定林分材積內)에 포함(包含)되어 있는 것은 단순임의추출법(單純任意抽出法)과 복합비추정법(複合比推定法)뿐이다. 단순임의추출법(單純任意抽出法)이 좋은 결과(結果)를 갖어온 것은 임분(林分)의 구성상태(構成狀態)가 단순동령림(單純同齡林)이기 때문이라 추측(推測)된다. 추정시(推定時) 측정(測定)이나 계산(計算)이 간편한것은 (1) 단급법(單級法) (2) 단순임의추출법(單純任意抽出法) (3) 표준목비추정법(標準木比推定法) (4) 분리비추정법(分離比推定法) (5) 복합비추정법(複合比推定法)의 순(順)으로 되어 정도면(精度面)이나 실제임분(實際林分) 재적(材積) 측정시(測定時) 시간경비(時間經費) 노력(勞力)을 비교적(比較的) 적게 들이고 측정(測定)할수 있는 방법(方法)은 적어도 인공일제림(人工一齊林)에서는 단순임의추출법(單純任意抽出法)이 가장 좋은 결과(結果)를 가져왔다고 본다.

• 한국안전학회지
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• 제13권3호
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• pp.96-101
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• 1998

In order to study the change in mechanical properties and anti-flammablilty of ethylene-ethylacrylate copolymer(EEA) very low density polyethylene(VLDPE) compound that could be used as communication cable sheath using $Mg(OH)_2$ as a non-toxic flame retardant, 100, 125, and 150phr $Mg(OH)_2$ were added to 100 parts of EEA-VLDPE compound, 100 EEA : 0 VLDPE, 50 EEA : 50 VLDPE, and 0 EEA : 100 VLDPE, respectively. $Mg(OH)_2$ was a good non-toxic flame retardant for communication cable sheath and anti-flammability increased with the amount of $Mg(OH)_2$ in compound. The mechanical properties-MI, Ts, and Eb-decreased with increasing in the mixing ratio of EEA but oxygen index(OI) increased with increasing in the amount of EEA. The best composition of $Mg(OH)_2$ in this study was 150phr to 50 EEA : 50 VLDPE compound for the anti-flammability.

• 콘크리트학회논문집
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• 제18권1호
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• pp.57-64
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• 2006

콘크리트에 균열이 발생하면 구조물의 구조적인 결함, 내구성 저하, 외관손상 등을 유발하여 치명적인 손실을 초래하기 때문에 균열제어를 통한 내구성능의 증대가 필수적이다. 국내 콘크리트 구조물의 동향을 살펴보면 LCC개념에 비추어 구조물의 신축비용이 25%에 불과하고, 다양한 형태의 균열보수, 개수, 유지관리 및 폐기처분에 대한 비용이 75%를 차지함에 따라 구조물의 시공시 콘크리트의 균열발생과 시공 후 콘크리트 내 철근부식을 억제하는 기술이 요구된다고 할 수 있다. 본 연구에서는 1990년대 후반부터 인산(H3PO4) 및 불산(HF)을 제조하는 공정 중에 액상형태의 부산물로 회수되는 불화규산(H2SiF6)을 활용하여 안정한 액상형태로 제조되는 규불화염계 화합물에 의한 균열저감 특성과 내구성에 대한 검토를 수행한 결과, 규불화염계 무기 조성물의 첨가로 수밀성이 증진되어 치밀한 경화조직을 형성함으로써 경화 후 급격한 수분의 손실에 따른 경화수축이 억제되어 건조수축을 저감시키는 특성을 발휘하였다. 또한 수화온도 및 수축 저감에 의해 조기에 균열발생을 억제하고, 수밀성을 증진시킴으로써 중성화, 동결융해저항성 및 염소이온침투깊이에 있어서 무첨가 콘크리트에 비해 상당히 개선되는 효과를 확인하였다. 마지막으로, 콘크리트 변형이 크게 발생되는 복합열화 환경 하에서도 SWP-2에 의한 내구성 향상 효과가 확인되었다.