• 멤브레인
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• 제27권3호
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• pp.263-272
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• 2017

분리막의 기공 크기 및 분포도를 분석하기 위한 다양한 측정법이 있지만 10-50 nm 범위의 한외여과막 기공크기를 정확하게 측정하기가 까다롭다. 따라서 gas-liquid displacement porometer (GLDP)와 liquid-liquid displacement porometer(LLDP) 기공 특성 측정법 두 가지를 이용하여, 10-100 nm의 기공크기를 갖는 세 종류의 세라믹 분리막(K-100, A-100, A-20)의 기공 크기 및 분포도를 비교 분석하였다. GLDP는 한외여과막의 최대 기공크기를 측정하는데 적합한 분석법으로 확인되었고, LLDP로 측정된 평균 기공크기가 분리막의 분리 성능 결과와 더 연계되어 있었다. 또한 LLDP는 10-50 nm 범위의 기공크기를 측정하는데 적합한 기공 분석법으로 확인되었으나, GLDP 보다 낮은 정밀도와 높은 민감도를 나타내었다. 다양한 기공 특성 분석법 가운데, 최근 상용화된 LLDP 기술은 종래의 측정법으로 알지 못했던 유용한 결과들을 제공할 수 있을 것으로 기대된다.

• 유기물자원화
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• 제27권4호
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• pp.61-70
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• 2019

본 연구는 농가에서 손쉽게 구할 수 있는 농축수산 부산물인 어분, 골분, 참깨박을 대상으로 액비 발효과정 중 이화학성 특성과 제조된 액비 처리에 따른 무 종자 발아 및 토마토 처리에 따른 작물 생육과 토양 환경에 미치는 영향을 검토하고자 수행하였다. 어분, 골분, 참깨박 액비 제조 시 발효기간 동안 액비의 pH는 발효가 진행될수록 골분 > 어분 > 참깨박 액비 순으로 높아졌으며 EC농도는 액비 3종 모두 30일까지 급격히 증가하다가 이후 변화가 적은 것으로 나타났다. 액비의 질소 함량은 발효가 진행될수록 모두 증가하였으며 어분 > 골분 > 참깨박 액비 순으로 높았다. 인산 함량도 발효가 진행될수록 증가하였으며 참깨박 액비가 1.0 % 로 가장 높게 나타났다. 액비 종류별 희석배수에 따른 무 종자의 발아율과 발아지수 결과는 어분과 참깨박 액비 10배 희석 처리구를 제외하고는 모든 처리구에서 95 % 이상의 발아율을 나타냈으며 발아지수는 액비가 희석될수록 증가하는 경향을 나타냈다. 액비 처리에 따른 토마토 생육 및 수량은 액비 처리간에 유의한 차이는 없었으며 화학비료 처리구에 비해 토양 중 유기물 함량, 미생물 밀도 그리고 미생물체량이 높게 나타났다. 이러한 결과로부터 유기자원을 활용한 액비 특성은 재료에 따라 차이가 있으며 유기농작물 재배 시 액비 시용으로 양분관리가 가능할 것으로 판단되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권3호
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• pp.396-401
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• 2006

A total of 72 castrated, crossbred ($Landrace{\times}Yorkshire$) piglets ($5.7{\pm}0.7kg$ BW) were allotted to one of three treatments including: a dry crumbled feed fed for 40 days; liquid feed provided for 10 days followed by dry crumbled feed for 30 days; and liquid feed provided for 20 days followed by dry crumbled feed for 20 days. Liquid feed was produced fresh each day by mixing water with dry crumbled feed at a ratio of 3:1. Pigs fed liquid feed for 10 days had a higher weight gain during the first 10 days (+16.8%; p = 0.01) and over the entire experimental period (+4.9%; p = 0.07) than pigs offered dry feed. Pigs fed liquid feed for 20 days also had a higher weight gain during the period from d 0 to 10 (+12.8%; p = 0.01), from d 10 to 20 (+8.5%; p = 0.06) and from d 0 to 20 (+9.7%; p = 0.01) than pigs offered dry feed. Pigs fed liquid feed for the first 10 days had higher feed intakes from d 0 to 10 (+22.6%; p = 0.01) and from d 0 to 40 (+5.3%; p = 0.02) than pigs offered dry feed. Pigs fed liquid feed for the first 20 days had a higher feed intake from d 0 to 10 (+21.8%; p = 0.01), from d 10 to 20 (+10.6%; p = 0.06), from d 0 to 20 (+14.6%; p = 0.01) and from d 0 to 40 (+6.6%; p = 0.02) than pigs offered dry feed. Feed conversion from d 0 to 40 tended to be poorer for pigs fed liquid feed during the first 20 days (p = 0.08) indicating an increase in feed wastage with liquid feeding. Nutrient digestibility at day 10 was unaffected by dietary treatment. However, at day 30, pigs fed liquid feed for 10 days had higher digestibility of dry matter (p = 0.08), energy (p = 0.10), crude protein (p = 0.03) and neutral detergent fibre (p = 0.05) than pigs fed liquid feed for 20 days. In conclusion, liquid feeding for 10 or 20 days increased the performance of weaned pigs during the specific time period that liquid feeding occurred but there were no carry over effects into subsequent production periods.

• 한국환경과학회지
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• 제18권5호
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• pp.589-594
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• 2009

The goals of this study were conducted to investigate the effects of applying liquid aluminum chloride ($AlCl_3$) to rice hulls on pH and soluble reactive P (SRP). A total of 800 broiler chicks (4 treatments $\times$ 4 replicates $\times$ 50 birds) were housed into 16 floor pens in a single house for 5 weeks. The treatments were divided into 4 groups: control, 100 g of liquid $AlCl_3/kg$ of rice hulls, 200 g of liquid $AlCl_3/kg$ of rice hulls, and 300 g of liquid $AlCl_3/kg$ of rice hulls. Liquid $AlCl_3$ was sprayed on the rice hulls surface at a rate of 100 g, 200 g, and 300 g liquid $AlCl_3$ per kg rice hull. pH values and SRP contents were significantly decreased (P<0.05) with the increased liquid $AlCl_3$ levels in comparison with control. However, no significant differences in SRP contents were observed among all treatments at 3 and 4 weeks. Applying 100 g, 200 g, and 300 g liquid $AlCl_3$ to rice hulls reduced SRP contents by 18, 25, and 52% for 5 weeks, respectively, compared with the controls. In conclusion, these results suggest that using liquid $AlCl_3$ on rice hulls should be promising for reducing water contamination and resulted in a reduction in SRP contents, which reduced pH.

• 한국산학기술학회논문지
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• 제13권9호
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• pp.4334-4340
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• 2012

본 연구에서는 미세 액적을 발생시키는 액적 발생 장치를 개발 제작하고 이에 대한 성능 평가를 실시하였다. 액적 발생 장치는 spray-evaporation method를 기초로 제작하였으며, 0.3mm, 0.5mm의 오리피스를 사용하였다. 압축 공기 공급 압력을 1bar에서 4bar로 증가시키면서 공급 압력에 따른 발생되는 액적 크기의 미세 정도를 비교하였다. 또한 SMPS(Scanning Mobility Particle Sizer)와 OPC(Optical Particle Counter)를 이용하여 서로 다른 오리피스를 장착한 액적 발생 장치에서 발생되는 액적의 크기 분포를 측정하였다. 연구 결과, 0.3mm 오리피스를 장착한 장치에서 발생되는 액적은 $0.3{\mu}m$ 인근의 크기가 가장 많았으며, 미립화되는 입자는 매우 안정적이었다. 또한 0.5mm 오리피스를 장착한 장치가 0.3mm 오리피스를 장착한 장치에 비해 발생되는 액적의 크기가 큰 것으로 나타났다. 이러한 액적 발생 장치는 입자의 미세한 응집 현상이 나타나는데, 이것은 내부 액체가 미세한 액적으로 미립화되어 분사되기 때문인 것으로 사료된다. 본 연구에서 제작한 액적 발생 장치는 미세 입자를 미립화하기 위한 에어로졸 발생 장치로 사용 가능한 것으로 판단된다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.645-649
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• 2009

Liquid desiccant cooling technology can supply cooling by using waste heat and solar heat which are hard to use effectively. For compact and efficient design of a dehumidifier, it is important to sustain sufficient heat and mass transfer surface area for water vapor diffusion from air to liquid desiccant on heat exchanger. In this study, the plate type heat exchanger is adopted which has extended surface, and hydrophilic coating and porous layer coating are adopted to enhance surface wettedness. PP(polypropylene) plate is coated by porous layer and PET(polyethylene terephthalate) non-woven fabric is coated by hydrophilic polymer. These coated surfaces have porous structure, so that falling liquid film spreads widely on the coated surface foaming thin liquid film by capillary force. The temperature of liquid desiccant increases during dehumidification process by latent heat absorption, which leads to loss of dehumidification capacity. Liquid desiccant is cooled by cooling water flowing in plate heat exchanger. On the plate side, the liquid desiccant can be cooled by internal cooling. However the liquid desiccant on extended surface should be moved and cooled at heat exchanger surface. Optimal mixing and distribution of liquid desiccant between extended surface and plate heat exchanger surface is essential design parameter. The experiment has been conducted to verify effective surface treatment and distribution characteristics by measuring wall side flow rate and visualization test. It is observed that hydrophilic and porous layer coating have excellent wettedness, and the distribution can be regulated by adopting holes on extended surface.

• 대한기계학회논문집
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• 제18권12호
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• pp.3276-3286
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• 1994

In most direct contact liquid-liquid heat exchangers, oil or hydrocarbon with a density less than water is normally used as dispersed working fluid. The main difficulty that arises with this arrangement lies in the control of the interface at the top of the column. When it is connected with a solar collector which uses water as its working fluid, the main difficulties arise from the fact that the water can be frozen during winter time. In order to solve these problems and to demonstrate the technical feasibility of a direct contact liquid-liquid heat exchanger, liquids heavier than water with low freezing temperature has been utilized as dispersed phase liquids in a small laboratory scale model made of pyrex glass. In the present investigation, dimethyl phthalate(C/sub 6/H/sub 4/)COOCH/sub 3/)/sub 2/) and diethyl phthalate (C/sub 6/H/sub 4/(CO/sub 2/C/sub 2/H/sub 5/)/sub 2/) are utilized as heavy dispersed phase working fluids. The results of the present investigation the technical in the utilization of heavier dispersed working liquid in the spray-column liquid-liquid heat exchanger for a solar system. The overall average temperature difference along the column is found to be almost half of the initial temperature difference between the dispersed and the continuous phase. Despite the fact that the two phthalates tested in the experiment differ significantly in some of their physical properties, the volumetric heat transfer coefficients in terms of dispersed fluid superficial velocities were found to be similar for both phthalates tested.

• 한국토양비료학회지
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• 제42권5호
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• pp.323-329
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• 2009

This study was conducted to analyze growth responses of fast growing tree species(8 clones of hybrid poplars, Salix alba, Metasequoia glyptostroboides, Liriodendron tulipifera, Acer okamotoanum, and Quercus palustris), the chemical characteristics of soil and $NO_3-N$ concentration of groundwater in a plantation applied with liquid pig manure. Concentrations of nitrogen and phosphorous in the soil treated with liquid pig manure were higher than that of the soil treated without liquid pig manure. With the exception of S. alba, DBH(Diameter at Breast Height) growth of all the fast growing tree species treated with liquid pig manure was higher than that of the species treated without liquid pig manure. In liquid pig manure treatment group, P. euramericana 'Eco28' clone showed the best performance in height and DBH growth. Concentration of nitrogen in the leaf with liquid pig manure was higher than that of the leaf treated without liquid pig manure. Based on the $NO_3-N$ concentration of groundwater analyzed during the experimental period, there was no evidence that groundwater was polluted by the liquid pig manure applied at the plantation.

• 한국추진공학회지
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• 제26권2호
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• pp.47-59
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• 2022

비추력이 가장 높은 액체수소/액체산소 엔진은 발사체의 성능을 극대화하기 위하여 1950년대 부터 개발되어 현재까지 이용되고 있다. 최근 국내에도 수소 경제의 대두에 따라 세계 수준의 액체수소 생산, 운송 등 인프라 구축이 진행되고 있고, 이는 발사체 성능을 향상시킬 수 있는 절호의 기회다. 본 논문에서는 액체수소 엔진 개발을 위한 전반적인 측면을 살펴보았다. 추진제로서의 액체수소 적용의 타당성을 고찰하고, 국내의 액체수소 인프라 현황, 액체수소 엔진 개발을 위한 소요기술, 수소를 안전하게 다루기 위한 운용적 측면을 검토하고, 액체수소 엔진 개발을 위한 시험설비를 검토하였다.

• Structural Engineering and Mechanics
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• 제81권6호
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• pp.691-703
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• 2022

To obtain the seismic response of lead-cored rubber, shape memory alloy (SMA)-rubber isolation Plate-shell Integrated Concrete Liquid-Storage Structure (PSICLSS), based on a PSICLSS in a water treatment plant, built a scale experimental model, and a shaking table test was conducted. Discussed the seismic responses of rubber isolation, SMA-rubber isolation PSICLSS. Combined with numerical model analysis, the vibration characteristics of rubber isolation PSICLSS are studied. The results showed that the acceleration, liquid sloshing height, hydrodynamic pressure of rubber and SMA-rubber isolation PSICLSS are amplified when the frequency of seismic excitation is close to the main frequency of the isolation PSICLSS. The earthquake causes a significant leakage of liquid, at the same time, the external liquid sloshing height is significantly higher than internal liquid sloshing height. Numerical analysis showed that the low-frequency acceleration excitation causes a more significant dynamic response of PSICLSS. The sinusoidal excitation with first-order sloshing frequency of internal liquid causes a more significant sloshing height of the internal liquid, but has little effect on the structural principal stresses. The sinusoidal excitation with first-order sloshing frequency of external liquid causes the most enormous structural principal stress, and a more significant external liquid sloshing height. In particular, the principal stress of PSICLSSS with long isolation period will be significantly enlarged. Therefore, the stiffness of the isolation layer should be properly adjusted in the design of rubber and SMA-rubber isolation PSICLSS.