• 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.

• Journal of Forest and Environmental Science
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• 제37권1호
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• pp.79-89
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• 2021

Cement bonded boards of 10 mm in thickness were produced from the mixture of Gmelina arborea sawdust and corn cob particles. The strength and dimensional stability of cement bonded composites produced from these two mixtures were examined. A total of thirty experimental boards were produced at density level of 1,000 kg/㎥ with cement to fibre ratio of 2.5:1 and 3:1 and five (5) blending proportions of G. arborea sawdust to corn cob particles of 100:0; 75:25; 50:50; 25:75 and 100:0. The effect of the cement to fibre ratio and blending proportion on the Water Absorption (WA), Thickness Swelling (TS), Modulus of Rupture (MOR), and Modulus of Elasticity (MOE) were determined. The result indicates that as the mixing ratio of cement to fibre and blending proportion of maize cob (75%) to G. arborea (25%) increased, the thickness swelling, water absorption decreased, whereas the MOR and MOE increased. It also shows that most dimensionally stable and flexural strength boards were produced at the highest level of mixing ratios (3:1) and blending proportion of G. arborea to corn cob 25:75. However, the analysis of variance shows that TS and WA were significantly different, whereas, MOE and MOR were not significantly affected by mixing ratios and blending proportions. Finding of this study has shown that maize cob particles are suitable for cement bonded board production.

• 한국세라믹학회지
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• 제16권3호
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• pp.178-183
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• 1979

The carborundum abrasive specimens bonded with a soda-borosilicate glass were prepared. Samples fired at specified temperatures with various mixing ratio and forming pressure were examined in terms of the structure, bonding strength, and microscopic observations. Increasing the forming pressure up to 400kg/$\cm^2$, the structure became denser in proportion to the forming pressure. The bonding strength was generally increased with increasing the mixing ratio (Vb/Vg), but the bloating phenomena were observed when samples were fired above 95$0^{\circ}C$ with mixing ratio above 20%, consequently, the bonding strength was decreased. Samples fired at the temperature range 900~95$0^{\circ}C$ with mixing ratio 15~30% had the dense structure with various grades.

• 대한기계학회논문집B
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• 제29권8호
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• pp.934-939
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• 2005

Starting pressure of a supersonic ejector with a second-throat was investigated. In case of mixing chamber length longer than a critical length, starting pressure is in proportion to length of the mixing chamber. In this study, we assumed that the ejector starts when the primary supersonic flow reaches inlet of the second-throat and the distance of the supersonic flow traveling can be expressed by multiplying an empirical factor to the first diamond shock length of overexpanded flow. To calculate the overexpanded supersonic flow, a mixing model was employed to compute secondary flow pressure and the result was applied to back pressure condition of overexpanded flow calculation. In the result, for three cases of primary nozzle area ratio, we could get accurate model of predicting the starting pressure by selecting a suitable empirical factors around 3.

• 보존과학회지
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• 제32권3호
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• pp.299-312
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• 2016

사적 제248호 대한의원은 서울대학교병원의 전신으로 대한제국시기에 만들어진 초대형 의료기관이다. 대한의원 동1병동의 건축은 1908년 초축 이후 두 차례(1935년, 1954년)의 증축과정을 거쳐 크게 세 시기로 구분된다. 콘크리트 기초에 대한 재료학적 분석 결과, 모든 시기의 기초부는 모르타르와 암석 골재로 이루어져 있으나, 시기별로 골재의 특징과 비율이 다른 것으로 나타났다. 건축시기별 콘크리트의 배합비를 산출하고 초음파 속도와 반발경도를 이용하여 물성을 산정하였다. 이 결과, 모르타르와 골재의 비율은 1954년의 기초부에서 1:35로 가장 높은 골재 비율을 보였으며, 초음파 속도와 일축압축강도는 1954년 기초부에서 각각 평균 450 m/s와 18.92 MPa로 가장 낮게 나타났다. 이와 같은 시기별 물성 차이는 골재의 배합특성과 공극률에 따라 발생한 것으로 해석된다.

• 한국축산시설환경학회지
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• 제6권3호
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• pp.133-140
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• 2000

This study was carried out to determine a suitable mixing rate to utilize the PDF as a bedding materials at the pigpens and investigate the effect of substitute processed dustproof fly-ash(PDF) on the odor. In proportion to the increase of substitute rate of the PDF, the utilizable period was extended, and there was a little change of the moisture in the bedding materials. At all the treatment of PDF, there was the significant effect on the maggots and parasites but it didn\`t hinder in the biodegradation. According to highly mixing rate, PDF decreased in the noxious gas ($NH_3$ and $H_2$S) emission. In conclusion, the mixing rate of 30% or above this substituted level will increase replacement terms, and reduce the sawdust cost and the pollutions of breed pigs.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.73-77
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• 2008

Structural lightweight concrete will reduced total loads of supporting sections and foundations in archtectural and civil structures. So, the lightweight concrete can be used widely for various purpose in the archtectural and civil structures. This paper were examined the influence of the mixing factor on the fresh and hardened properties of lightweight concrete that are used 2types of the differences properties of lightweight aggregates. According to types of lightweight aggregates, the case of synthetic lightweight aggregate are have need higher s/a; 2~4% on mixing proportion. Lightweight concrete was somewhat exhibit lower compressive strength than ordinary concrete. However it was not showed a marked difference. According to types of lightweight aggregates, the case of synthetic the lightweight aggregate are highest performance in fresh and hardened concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.30-31
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• 2021

This study aims to build a deep learning model that can predict the value of concrete mixing properties according to a given concrete strength value. A model was created for a total of 1,291 concrete data, including 8 characteristics related to concrete mixing elements and environment, and the compressive strength of concrete. As the deep learning model, DNN-3L-256N, which showed the best performance on the prior study, was used. The average value for each characteristic of the data set was used as the initial input value. In results, in the case of 'curing temperature', which had a narrow range of values in the existing data set, showed the lowest error rate with less than 1% error based on MAE. The highest error rate with an error of 12 to 14% for fly and bfs.

• 오토저널
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• 제15권2호
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• pp.44-52
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• 1993

In this study, the characteristics of decreasing exhaust gas of diesel engine was examined in dual fuel method by using commertial LPG for automotive. LPG was supplied to engine intake port by fumigation method and flow rate was controlled by using the needle valve. LPG supply ratios were 0, 20, 30% of total fuel amount to be supplied to engine by mass base. We investigated the effect of LPG supply ratio on exhaust gas concentrations related to excess air ratio and engine load at 1600, 1800, 2000 rpm. Soot concentration decreased about 30% in proportion to the increase of the LPG supply ratio. NOx concentration decreased in proportion to the increase of the LPG than diesel only and the increase rate was higher at low engine load. BSFC(Brake specific fuel consumption) was lower in proportion to the increase of the LPG supply ratio at high engine load and to the decrease of LPG supply ratio at low engine load.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2002년도 학술.기술논문발표회
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• pp.67-76
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• 2002

Self-leveling material(SLM) is one of the floor finishing materials which make flat surface like as water level by itself in a short time. So it is possible to increase construction speed and enhance economical efficiency. In this study, author intended to develop SLM for the industrial warehouse and factory loading heavy weight machinery and vehicles. The demanded properties for this type of SLM are above 20mm of flow value and above 300kgf/cm2 of 28-days compressive strength. To possess demended strength and fluidity, SLM have to be composed of many types of binders and chemical additives. So it is difficult to decide suitable mixing proportion of composition materials. In this study, author investigated the weight percentage effect of main composition materials for high-strength self-leveling material, by experimental design such as tables of orthogonal arrays and simplex design, and by statistical analysis such as analysis of variance and analysis of response surface. Variables of experiments were ordinary portland cement(OPC), alumina cement(AC), anhydrous gypsum(AG), lime stone(LS) and sand, and properties of tests were fluidity of fresh state and strength of hardened state. Results of this study are showed that suitable mix proportions of binders for the high strength self-leveling materials are two groups. One is 78~85.5% OPC, 7.5~9.5% AC, 9~12.5% AG and the other is 72.5~78% OPC, 9~12.5% AC, 13~l5% AG.