• Applied Chemistry for Engineering
• /
• v.25 no.4
• /
• pp.409-413
• /
• 2014

This study was carried out to design the optimum mixing ratio of aggregate, cyclic aggregate, and binder (moisture, emulsified asphalt, and emulsion type additives) and produce recycling cold asphalt paving mixture satisfying site work standard. The cyclic aggregate satisfying KS F 2572 was collected from waste asphalt by adequate processing. As the moisture content increased, the shearing strength was decreased. The maximum marshall stability was shown at the 3.0 wt% moisture content. So the optimum moisture content was 3.0 wt%. The marshall stability and flow value with the amount of emulsified asphalt was satisfied in the range of 0.5~2.5 wt%, and the porosity was satisfied in the range of 0.7~2.5 wt%. So the optimum amount of emulsified asphalt was 1.6 wt%. The optimum amount of emulsion type additive was 0.1 wt% in the light of marshall stability and degree of saturation of recycling cold asphalt mixture.

• Membrane Journal
• /
• v.17 no.3
• /
• pp.197-209
• /
• 2007

In this study, a multi-staged pilot-scale membrane plant was constructed and operated for the separation of $CO_2$ from LNG-fired boiler flue gas of 1,000 $Nm^3/day$. The target purity and recovery ratio of $CO_2$ required for the pilot plant were 99% and 90%, respectively. For this purpose, we previously developed the asymmetric polyethersulfone hollow fibers and evaluated the effects of operating pressure and feed concentration of $CO_2$ on separation performance[1,2]. The permeation data obtained were also analyzed in relation with the numerical simulation data using counter-current flow model[3,4]. Based on these results, we designed and prepared the demonstration plant consisting of dehumidification process and four-staged membrane process. The operation results using this plant were compared with the numerical simulation results on multi-staged membrane process. The experimental results matched well with the numerical simulation data. The concentration and the recovery ratio of $CO_2$ in the final stage permeate stream were ranged from $95{\sim}99%$ and $70{\sim}95%$, respectively, depending on the operating conditions. This study demonstrated the applicability of the membrane-based pilot plant for $CO_2$ recovery from flue gas.

• Applied Biological Chemistry
• /
• v.51 no.3
• /
• pp.177-182
• /
• 2008

This study was carried out to investigate the reaction of lipase-catalyst transesterification using animal fat recovered from fleshing scrap generated during leather making process. Transesterification reaction between fat and primary or secondary alcohol was carried out under the condition of immobilized enzyme catalyst. The conversion rate was the highest when 1.5 mole of methanol was injected by 4 times. As for lipase, Candida antarctica showed the highest conversion rate of 82.2% among the 4 different lipases. It was found that water contained in the fat causes lower conversion rate. The condition of 1.2wt. % of water in the fat decreased the conversion rate by 40%. It was considered that the resulted reactant, fatty acid ester could be used as raw material for biodiesel with the characteristics of not generating SOx and diminishing smoke.

• Clean Technology
• /
• v.13 no.4
• /
• pp.257-265
• /
• 2007

As a basic study for the development of pilot-scale distillation process of waste photoresist strippers from semiconductor industry, lab-scale experiments for the recovery of NMP (N-methy1-pyrrolidione) and BDG (Butyldiglycol) from waste photoresist strippers have been made using a spinning band vacuum distillation column. Purities of NMP and BDG obtained from the present experiments were higher than 99.5%. Furthermore, water content was less than 1000 ppm, color grade(APHA) less than 50, most metal contents except sodium less than 1 ppb. Those results indicate that NMP and BDG reclamed by distillation satisfy the their specifications required for the formulation of new photoresist strippers. Recovery rate of NMP and BDG was 96 and 53%, respectively, for type A, and 93 and 57%, respectively, for type B waste PR stripper solution.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.7 no.3
• /
• pp.153-156
• /
• 1987

With a purpose of evaluation rye crop as winter green feed, a cultivar was sown in autumn and harvested at booting, heading, milk, dough and yellow-ripe stages, and processed into silage. The quality of the silage was assessed in terms of ammonia-N, recovery rate in dry matter, pH, and the composition of organic acids. The results obtained are: 1. The recovery rate in dry matter from the silage was the highest when harvested at yellow stage (P<0.01). The ratio of ammonia-N to total-N was low when the rye crop was harvested during milk (9.4%) and dough ( 12.7%) stages (P$NH_3-N$. 3. Silage quality based on the composition of organic acids was highly evaluated when the crop was harvested during milk, and dough stages. 4. Considering both the DM yield and quality of the silage, it was found that rye crop should be harvested at dough stage and ensiled.

• Korean Chemical Engineering Research
• /
• v.40 no.6
• /
• pp.694-702
• /
• 2002

Activated carbons have been used as adsorbents in various industrial application, such as solvent recovery, gas separation, deodorization, and catalysts. In this study, the effects of residual water on the activated carbon adsorbent surface on the adsorption capacity of $CCl_4$ were investigated. Adsorption behavior in a fixed bed was studied in terms of feed concentration, flow rate, breakthrough curve and adsorption capacity for $CCl_4$. Desorption characteristics of residual water on activated carbon were also studied. The water contents of the activated carbon were varied in the range of 0-20%(w/w) and all experiments were performed at 298.15 K. The adsorption equilibrium data $CCl_4$ on the activated carbon were well expressed by Langmuir isotherm. The adsorption capacity of $CCl_4$ decreased with increasing residual water content. Desorption of residual water in activated carbon decreased expotentially with $CCl_4$ adsorption. The obtained breakthrough curves using LDF(linear driving force) model represented our experimental data.

• Korean Journal of Soil Science and Fertilizer
• /
• v.34 no.4
• /
• pp.292-301
• /
• 2001

The objectives of this study were to measure the changes in soil moisture regimes and the distribution patterns of inorganic N derived from the fertigated $^{15}N$-labeled urea, and compare them with the results obtained from broadcast-applied soil under the same drip irrigation domain. In fertigated soil, a $^{15}N$-labeled urea solution of $117mg\;N\;L^{-1}$ was applied by surface drip irrigation for 4 weeks. In broadcast-applied soil, no the other hand, 4 g of $^{15}N$-labeled urea(1.87 g N) mixed thoroughly with 5 kg of soil was placed on the surface of packed soil. Soil water status was controlled by drip irrigation scheduled at soil matric potential of -50 kPa. A calibrated time-domain reflectometry probe was installed in the soil vertically 15 cm apart from a drip emitter to control drip irrigation. About 60% of urea-derived inorganic nitrogen was remained in the top zone between 0 and 10 cm depth of fertigated soil, while, most of the inorganic nitrogen (91%) was accumulated in the top zone of broadcast-applied soil. Of inorganic nitrogen derived from urea, the percentage of $NO_3{^-}$ was much higher for fertigation (99%) than for surface application (62%). The relatively lower recovery of urea-derived inorganic nitrogen of broadcast-applied urea-N (51%) than that of fertigated urea-N (89%) was attributable to enhanced $NH_3$ volatilization.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.32 no.8
• /
• pp.1193-1199
• /
• 2003

As a result of resistant starch yield depending on heating temperature, moisture content, storage temperature and heating-cooling cycle with RSM (response surface methodology), high amylose corn starch (46%) was appeared higher than normal corn starch in the yield (22%). At the high amylose corn starch, optimum conditions for resistant starch formation were 6 times of heating-cooling cycle, 108$^{\circ}C$ heating temperature and 67% moisture content at the 2$0^{\circ}C$ storage temperature, which resulted in 25% yield with these experiment conditions. Affecting factor for the resistant starch formation was arranged according to heating -cooling cycle, moisture content, heating temperature and storage temperature. Raw corn starch granule was destructive and appeared a porous reticular structure by the resistant starch formation. Color became dark and increased yellowness by caramelization during heating processing. Heating-cooling processing was the result of decreased hardness, cohesiveness, springiness and gumminess.

• Korean Journal of Soil Science and Fertilizer
• /
• v.41 no.3
• /
• pp.177-183
• /
• 2008

Sodium is known to reduce a plant growth and yields. However, the relationships between physiological response of seedling and salinity stress caused by growing media are not well understood yet. We conducted experiments to investigate change of some parameters including Na, EC, moisture content in media under different air temperature ($15^{\circ}C$, $25^{\circ}C$), and the response of fruit-vegetables such as cucumber, oriental melon on saline conditions originated from horticultural substrate. Volumetric moisture content of media at $15^{\circ}C$ was 70%, but at $25^{\circ}C$ was decreased by 45% within 22 hrs, showing below optimal matric potential, approximately. During reaction time, the increase of Na concentration was significantly greater in saline substrate than in control. The decrease rate of Na concentration according to supplying irrigation water was higher in saline substrate than in control. $CO_2$ assimilation rate and transpiration rate of Korea melon grown in low temperature were decreased with a Na/cation ratio in hydroponic solution. Water saturation deficit was also increased significantly at $15^{\circ}C$ as compare to $25^{\circ}C$. Saline stress during nursery stage induced a reduction of seedling quality, growth and cucumber yield. The results suggest that the relationship between uncontrolled Na uptake of seedling from saline substrate and meteological condition is responsible for saline stress.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2003.07a
• /
• pp.187-192
• /
• 2003

우리나라의 밭작물 재배 시 잡초발생의 억제, 토양온도 및 수분 유지, 수량증수 등의 목적으로 약 274천㏊가 비닐피복재배를 하고 있으나, 한국자원재생공사에 의하면 2000년도 폐비닐 발생량중 약 48%만이 회수되고 있어 폐비닐에 의해 농토와 주변환경의 오염이 심각한 지경에 이르고 있다. 또한 폐비닐의 수거작업은 인력에 의존하고 있어 많은 노력이 들기 때문에 환경오염을 줄이고 수거노력 절감을 위해 기계화가 절실히 요구되고 있다. (중략)