• 한국구조물진단유지관리공학회 논문집
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• 제5권3호
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• pp.123-130
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• 2001

The purpose of this study is to suggest the non-destructive equation for the estimation of concrete strength by ultrasonic pulse velocity at the Age of 28day compressive strength of $600{\sim}1000kg/cm^2$. For this purpose, selected test variables were water-hinder ratio, replacement ratio of silica fume, binder content, maximum size of coarse aggregate and sand-aggregate ratio. From the results, the average increase or decrease of ultrasonic pulse velocity is 61m/sec for each 1% of moisture content. And the correlation equation between the ultrasonic pulse velocity and the compressive strength of concrete is as follows. $F_c=896.3V_p-3514$ ($R^2$ = 0.81) where, $F_c$ : compressive strength($kgf/cm^2$), $V_p$ : ultrasonic velocity(km/sec).

• 환경위생공학
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• 제15권3호
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• pp.24-30
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• 2000

In this study, to determine the optimum fermentation process for the feed production of food wastes and estimate the practical value of fermented feed using kudzu creeper and sawdust as bulking agent. This study considered initial C/N ratio control as the fermentation process variables. The result are summarized as follows. Minimum water contents of byproducts in the fermentation feed production showed 39%(kudzu), 37%(sawdust) at the C/N ratio 25 and 45%(kudzu, sawdust) at the C/N ratio 35. Temperature variations in the fermentation feed production at the C/N ratio 25 indicated $68^{\circ}C$(kudzu), $70^{\circ}C$(sawdust). Optimum condition of fermentation process of water content, C/N ratio and permeability (porous structure of the mixture). For optimum fermentation gravitationally dewatered garbage, the proper mixing ratios of kudzu(moisture contents : 17.3%) and sawdust(moisture contents : 13.2%) were 41% and 39%, respectively. Major biological reaction in the aerobic fermentation feed production occurred during 12~24hrs.

• 한국환경복원기술학회지
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• 제5권6호
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• pp.9-13
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• 2002

This study has been performed to investigate the physical and mechanical characteristics of compaction, volume change and compressive strength for reinforced soil mixed with cement. And confirm the reinforcing effects with admixture such as cement. To this end, a series of compaction test and compression test was conducted for clayey soil(CL) and cement reinforced soil. In order to determine proper moisture content and mixing ratio, pilot test was carried out for soil and cement reinforced soil. And the mixing ratio of cement admixture was fixed 3%, 6%, 9% and 12% by the weight of dry soil. As the experimental results, the maximum dry unit weight(${\gamma}_{dmax}$) was increased with the mixing ratio and then shown the peak at 10% reinforced soil, but the optimum moisture content(OMC) and the volume change was decreased with the ratio increase. And the compressive strength volume change was decreased with mixing ratio increased.

• 한국농공학회지
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• 제26권3호
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• pp.81-89
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• 1984

To examine the moisture adsorption and permeability characteristics, weathered granite soils of different degrees of weathering, cultivated upland soils and sands of Han-river were sampled. The results are as follows: 1. In case that the mother rock was same, the pF values under same moisture content decreased according as the grain size of soil became finer by the weathering process. 2. In case that the mother rock was different, the pF value varied by the behavior of clay minerals, and the cultivated upland soils showed more sensitive reaction than sands and fresh granite soils. 3. The pF value changed by the difference of primary moisture content and also influenced by soil structure, testing method and etc. 4. The pF value and compaction curve had close relation, however under same moisture content, the pF value decreased by the increment of density. 5. The permeability depend on the available void ratio between the soil particles according to the degree of weathering, and the pF value of available void water between the soil particles which related directly to permeability was about 3.3 except the void water holded in the soil particles. 6. As the above, the pF value and permeability were differentiated by degree of weathering, primary moisture content, density and etc. Therefore it is considered unreasonable to define uniformly by soil texture.

• 한국식품영양과학회지
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• 제41권4호
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• pp.561-565
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• 2012

떡볶이용 가래떡을 제조할 시 떡의 수분, 조직감 및 관능적 특성에 영향을 미칠 것으로 판단되는 조건인 수분함량을 달리하여 제조한 떡의 품질특성을 확인해보았다. 떡의 수분 함량은 쌀가루 대비 수분함량이 증가할수록 유의적으로 증가하였다. 기계적인 조직감에서 경도, 씹힘성 및 응집성은 가래떡 제조에 수분첨가량이 증가할수록 감소하였고 탄력성과 부착성은 유의적인 차이가 발견되지 않았다. 수분흡수율과 고형물 용출량을 측정한 결과 쌀가루대비 수분첨가비율이 증가할수록 수분흡수율은 증가하고 고형분 용출량은 유의적인 차이를 보이지 않았다. 관능검사를 실시한 결과 촉촉함은 수분함량이 가장 많이 첨가된 가래떡이 가장 높았고 경도와 탄력성은 쌀가루 대비 수분첨가 비율이 1:0.5에서 가장 낮게 나타났다. 전반적인 기호도는 쌀가루대비 수분첨가 비율이 1:0.3, 1:0.4 및 1:0.5인 가래떡 군에서 각각 5.75, 6.92 및 3.67로 1:0.4 처리군에서 가장 높았다. 쌀가루 대비 수분첨가 비율이 1:0.4일 때 가래떡의 촉촉함, 경도, 부착성, 탄력성 및 전반적인 기호도의 조화가 가장 적절한 것으로 나타나 식감이 우수한 떡볶이용 가래떡 제조에 적합한 것으로 확인되었다.

• Journal of Biosystems Engineering
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• 제16권3호
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• pp.248-262
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• 1991

Simulation model was developed to analyze drying process for tray type red pepper dryer and validated by experiments. This model could predict satisfactorily temperatures and moisture contents of red pepper and temperatures of drying air during drying. Optimize algorithm was developed to search control valiables (drying air temperature, air recycle ratio and air flow rate) of red pepper dryer based on a criterion of minimizing energy consumption under the constraint conditions that statisfied carotenoid retension of at least 210mg per 100g dry matter, the moisture content of bottom layer of 15% (d.b) and drying time of less than 35 hours. Step changes in drying air temperature and air recycle ratio were considered in the optimization. In single step in control variables, the difference of the moisture content between top layer and bottom layer was great and more fan power was required. As the drying trays were exchanged when the moisture content of bottom layer reached to 100% (d.b), fifty percent of energy was saved and the difference of moisture content was little. In double step changes in control variables, optimal conditions were found by changing the step when the moisture content of bottom layer reached to 100% (d.b) (about 19.8 hours from starting drying). Optimum air flow rate was $18.1cmm/m^2$. Optimum drying air temperature and air recycle ratio in the first step was $55.8^{\circ}C$ and 0.80, and in the second step $65.6^{\circ}C$ and 0.88, respectively. In triple step changes in control variables, the optimal conditions were found by changing the steps when the moisture content of bottom layer reached to 250% (d.b) and 150% (d.b). Optimal air temperatures were $66.2^{\circ}C$, $58.4^{\circ}C$ and $66.9^{\circ}C$, and optimal air recycle ratios were 0.778, 0.785, 0.862 at each step, respectively. Optimal air flow rate was $18.9cmm/m^2$. The best operating mode was triple step mode considering energy consumption, drying time, fan power, and quality of dried red pepper. When the triple step mode was used to dry the red pepper, the energy consumption was about 16.5%~57.2% less than that of the single step mode and the drying time was 6.6 hours shorter than that of the double step mode.

• 한국약용작물학회지
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• 제16권4호
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• pp.207-210
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• 2008

비닐하우스 내에서 일평균 투광율을 21.2%, 24.8%, 30.3%와 같이 3수준으로, 토양수분을 11.0%, 12.5%, 15.3%, 18.9%와 같이 4수준으로 조절하여 묘삼의 생육 및 수량을 조사한 결과는 다음과 같다. 엽록소 함량은 투광율이 낮은 조건에서 토양수분함량의 감소에 따라 완만히 감소되었으나 투광량이 높은 조건에서 토양수분함량이 낮아지면 엽록소 함량은 현저히 감소되었다.고온장해율은 투광율이 낮은 조건에서 토양수분함량이 11.0%처럼 매우 낮을 때에만 현저히 증가되었지만 투광량이 높은 조건에서는 토양수분함량의 감소에 따라 고온장해율은 급격히 증가되었다. 3.3$m^2$(칸)당 생근중, 주당 생근중 및 사용가능묘삼수는 투광율이 증가되고 토양수분함량이 감소될수록 뚜렷이 감소되었는데, 토양수분함량이 적절한 조건(18.9%)에서는 투광율이 증가되어도 묘삼수량의 감소는 적었으나 토양수분함량이 부족한 조건에서는 투광율이 증가될수록 묘삼수량은 현저히 감소되었다. 적변율은 투광율이 높고 토양수분함량이 많을 때 현저히 증가되었는데, 투광율이 높은 조건에서 토양수분함량이 감소되면 적변율도 차차 감소되었으며, 투광율이 낮은 조건에서 적변율은 토양수분함량에 따라 큰 변화를 보이지 않았다.

• 농업생명과학연구
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• 제44권1호
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• pp.25-32
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• 2010

본 연구는 수분함량에 따른 보리와 호밀 silage의 발효특성을 평가하기 위하여 수행하였다. 보리와 호밀의 수분함량은 수분첨가 또는 예건을 통해 50%, 65% 및 80%로 조절하였다. 보리 silage의 pH와 Lactate:Acetate 비율은 저수분 처리구 (4.54와 6.23), 호밀 silage에서는 중수분 처리구 (4.33과 9.24)가 가장 높았다. 보리 silage의 propionate 함량은 저수분 처리구가 고수분 처리구에 비해 높았으나, 보리와 호밀 silage의 lactate, 총휘발성지방산 및 acetate 함량은 고수분 처리구가 저수분 처리구에 비해 높았다. 보리 silage의 total-N 함량은 중수분 처리구가 저수분 처리구에 비해 높게 나타났으며, 호밀 silage는 저수분 처리구가 타 처리구에 비해 높았다. 보리 silage의 $NH_3-N$ 함량과 total-N:$NH_3-N$ 비율은 고수분 처리구가 높게 나타났다. 보리와 호밀 silage의 buffering capacity는 수분함량이 높을수록 증가하였으나, pH가 높을수록 감소하였다. 보리와 호밀 silage의 수분 함량은 pH와는 부(-)의 상관관계를 나타내었으나, 휘발성지방산과 $NH_3-N$ 함량 및 total-N중 $NH_3-N$ 비율과는 정 (+)의 상관관계를 나타내었다. 이상의 결과에서 보리와 호밀 silage 제조를 위한 적정 수분함량은 70~80%로 확인되었으며, 사료작물의 수분을 60%까지로 예건하는 것은 silage 품질 저하를 초래할 수 있는 것으로 사료된다.

• 한국환경농학회지
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• 제15권3호
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• pp.355-361
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• 1996

The Purpose of this study was to investigate the effect of the Change in the operating conditions on rotary turning compost plants. The major parameters investigated were moisture content and mixing of the sawdust and pig farm wastewater. Pig farm scale composting plants with mixing rotary were used in this study. Wastes used for the study were sawdust, pig manure, urine and wastewater. When the moisture content was 75%, the compost product obtained from the plants had better physical characteristics than that obtained from the plants with moisture contents of 70%, 80% and 85%.(two a day mixing). When the turning was twice a day, the compost product obtained from the plants had better characteristics than that obtained from non-mixing.(moisture content 75%). C/N ratio, pH value and coliform bacterial population were stable in the compost.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.403-408
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• 2000

Hardened concrete contains pores of varying types and sizes, and therefore the transport of air through concrete can be considered. The rate of permeability will not only depend on the continuity of pores, but also on the moisture contents in concrete. In this paper, the effects of curing conditions and moisture content ratios on the carbonation and air permeability are investigated according to the accelerated carbonation test. The results are follows. 1) Compressive strength, carbonation velocity and air permeability are influenced by the moisture content and curing method. 2) The relationship between carbonation velocity coefficient and air permeability coefficient has been quite well established.