• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.417-417
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• 2016

Global environmental deterioration has become more serious year by year and thus scientific interests in the renewable energy as environmental technology and replacement of fossil fuels have grown exponentially. Photoelectrochemical (PEC) cell consisting of semiconductor photoelectrodes that can harvest light and use this energy directly to split water, also known as photoelectrolysis or solar water splitting, is a promising renewable energy technology to produce hydrogen for uses in the future hydrogen economy. A major advantage of PEC systems is that they involve relatively simple processes steps as compared to many other H2 production systems. Until now, a number of materials including TiO2, WO3, Fe2O3, and BiVO4 were exploited as the photoelectrode. However, the PEC performance of these single absorber materials is limited due to their large charge recombinations in bulk, interface and surface, leading low charge separation/transport efficiencies. Recently, coupling of two materials, e.g., BiVO4/WO3, Fe2O3/WO3 and CuWO4/WO3, to form a type II heterojunction has been demonstrated to be a viable means to improve the PEC performance by enhancing the charge separation and transport efficiencies. In this study, we have prepared a triple-layer heterojunction BiVO4/WO3/SnO2 photoelectrode that shows a comparable PEC performance with previously reported best-performing nanostructured BiVO4/WO3 heterojunction photoelectrode via a facile solution method. Interestingly, we found that the incorporation of SnO2 nanoparticles layer in between WO3 and FTO largely promotes electron transport and thus minimizes interfacial recombination. The impact of the SnO2 interfacial layer was investigated in detail by TEM, hall measurement and electrochemical impedance spectroscopy (EIS) techniques. In addition, our planar-structured triple-layer photoelectrode shows a relatively high transmittance due to its low thickness (~300 nm), which benefits to couple with a solar cell to form a tandem PEC device. The overall PEC performance, especially the photocurrent onset potential (Vonset), were further improved by a reactive-ion etching (RIE) surface etching and electrocatalyst (CoOx) deposition.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.267-276
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• 2005

The study is to determine the feasibility of activated red mud as an anti-red tide material. The red mud, a byproduct of Bayer process for the production of alumina from bauxite, contained hematite, boehmite, calcite, sodalite, quartz, zircon, anatase and an unknown phase. In the adsorption study of the red mud, its adsorption efficiencies for heavy elements were close to $100\%$ except $92\%$ In As. These results seem to be attributed by the high adsorption ability of iron oxides for heavy elements. As a result of leaching tests with the red mud at various pHs (pH $1\∼13$), the high leaching efficiencies for As, Cu and Zn at low pHs (at acidic condition) were obtained. It indicated that removal efficiency of heavy elements could be excellent in acidic treatment of red mud. The activated red mud, red mud reacted with acid, contained hematite, boehmite and so on, and desorption of heavy metals from the activated red mud increased with increasing temperature. The grain of the activated red mud was tens nm in size. The removal efficiency for 5 types of plankton was generally in inverse proportion to pH, especially to final pH. Of five plankton types, Prorocentrum minimum and Alexandrium tamarense promptly were removed more than $90\%$ as soon as the activated red mud was sprayed and $100\%$ after 30 minutes. These results indicated that the activated red mud seems to be a promising anti-red tide material.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1186-1192
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• 2005

The relationship between bacteria and anaerobic archaea, sludge yield coefficient and nitrogen removal rate were investigated in intermittent aeration systems(I/A) with added archaea, I/A and conventional activated sludge system. As the archaea solution was added to the I/A reactor, organic removal rate as well as nitrogen removal rate increased. Also, sludge production rate in I/A system added the archaea was maintained lower than other systems because sludge yield coefficient was decreased due to the role of anaerobic archaea such as anaerobic degradation of organics. The experimental data supported the possibility of symbiotic activated sludge system with anaerobic archaea under intermittent aeration, leading to the enhanced nitrogen removal. Crucial results to be presented are: 1) specific oxygen utilization rate(SOUR) of the I/A-arch system was $2.9\;mg-O_2/(g-VSS{\cdot}min)$. SOUR and nitrification rate of the sludge from the I/A-arch system was higher than those from the I/A and A/S reactors. 2) Removal efficiencies of $TCOD_{Cr}$ in the I/A-arch, I/A and A/S reactors were 93, 90 and 87%, respectively. 3) Nitrification occurred successfully in each reactor, while denitrification rate was much higher in the I/A-arch reactor. Efficiencies of TN removal in the I/A-arch, I/A and A/S reactors were 75, 63 and 33%, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.7
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• pp.1096-1103
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• 1999

A study was conducted to clarify the impact of recombinant porcine somatotropin (pST) on the efficiency of absorbed nitrogen use for protein deposition in growing pigs. Three levels of dietary crude protein (9.0, 11.5, 14.0% CP) were used. Each had either a sub-optimum or near optimum lysine: CP concentration (Low-lysine, 3.8 g/100 g CP and High-lysine, 5.5 g/100g CP) in order to achieve different metabolic efficiencies for nitrogen deposition (ca. 45 vs. 60%). Twelve crossbred female pigs $(59{\pm}4kg\;BW)$ were placed in metabolism cages and fitted with bladder catheters. Each pig received an excipient injection daily for the first 10-d, a pST (5 mg/d) injection for the second 10-d, and then excipient for the last 10-d. Pigs were randomly assigned to one of six dietary treatments (2 pigs/diet) and fed 4 times per d at $92g/kg\;BW^{0.75}$ $(3{\times}maintenance)$. Means for the excipient period were compared to means for the pST period. Urinary nitrogen (N) output declined in pST-treated pigs (p<0.01) irrespective of dietary protein content or lysine level. Nitrogen retention increased by an average of 11% (p<0.01) with pST treatment (726 vs. $803mg\;N/kg^{0.75}\;BW/d$). Forty-eight percent of the absorbed N was retained with Low-lysine diets, but this increased to 53% with pST injection (+11%, p<0.01). Pigs fed High-lysine diets retained 62% of absorbed N which increased to 69% with pST (+11% p<0.01). the addition of lysine improved N use by 27% (High vs. Low, p<0.01), but the effect of lysine and pST was additive (+40%). Therefore, pST improves N retention and the efficiency of apparently absorbed N use in growing pigs (>60kg). It does so with diets having the potential for either low or high efficiencies of N use (48% and 62%). More work is needed to determine if the partial efficiency of N use improves in direct proportion to pST dose since the improvement in protein deposition is a function of pST dose.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.3
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• pp.23-32
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• 1982

This study was conducted to evaluate the temperature effects on the nightsoil, anaerobic digestion, whether it could be operated with a higher organic loading rate at a higher temperature during summer months, or with a lower organic loading rate at a lower temperature during winter months. A laboratory completely mixed digester was continuously operated at 11 different temperatures from $18.5^{\circ}$ to $60^{\circ}C$ with 30 days of HRT. The study results indicated that the best efficiency occurred at a temperature range of $35^{\circ}$ to $40^{\circ}C$, at which BOD and VS removal efficiencies were respectively 71 and 53 percent, and gas production rate was $0.6m^3/kg$ VS fed or $16m^3/m^3$ fed. BOD removal efficiency would be increased to 78 percent if the digester effluent settled for 24 hours. Since the digester efficiency decreased beyond this temperature range, this suggested the digester need not to operate a higher temperature even during the summer months. The laboratory results were in good agreement with those of the existing digester operated at a temperature range of $32^{\circ}$ to $40^{\circ}C$. Application of septage or cow manure to the digester with nights oil at a rate of 1 to 1 did not greatly affect the digester performances. In addition, the digester effluent could be treated aerobically without any dillution water. BOD and SS removal efficiencies were greater than 90 percent in this case.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.295-303
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• 2000

The water clarification efficiency was examined in a shallow wetland where dense vegetation was formed naturally in an abandoned paddy field. And, also two enclosure experiments were carried out to measure the effects of materials exchange between sediment and the overlying water with the existence of vegetation and accumulated litter. The hydraulic retention time of wetland was regulated in 1.2 day. The removal rates of SS (56%) and $NO_3-N$ (61%) were high, considering its short retention time. However, removal efficiencies of VSS (28%), COD (14%), DOC (1%),and TP (0.2%) were relatively lower. This low removal efficiencies were thought to be due to the release of dissolved form of organic matter and phosphorus from the sediment. Most of constituents except nitrate were higher in the enclosure at the beginning of enclosure installation than that of the outflowing water from wetland. And then, it has fluctuated and decreased with time. The wetland was in equilibrium state of settling, accumulation of organic debris, and regeneration of dissolved material from sediment. So ultimately high primary production by dense vegetation in the wetland may be the reason of unfavorable or low treatment efficiency of wetland after many years of operation for wastewater treatment. However, the water quality of effluent from the wetland showed smaller variation and better condition than that of inflow, especially during storm events. It can be concluded that this wetland is suitable for the improvement of water quality from nonpoint sources.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.3
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• pp.297-303
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• 1985

Three field experiments were conducted to define the optimum levels, yield responses and fertilization efficiencies of NPK fertilizers on peanut and survey on fertility status of 150 farmers` peanut fields was carried out for 3 years. The range of optimum rates of N, $P_2O_5$ and $K_2O$ fertilizers on peanut were 5.2-9.0, 6.4-21.0, 8.5-15.0kg/10a, respectively. The effect of NPK application were 23, 8, 16% and production efficiencies of each kg of NPK fertilizers were 6.0, 1.8, 3.4 kg, respectively. The optimum nutrient contents in soil were 250 ppm for available $P_2O_5$ and 0.8 me/100g for exchangeable K including applied ones. Available soil nutrient contents of farmers' peanut fields were mostly below the optimum range for upland soil.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.60-67
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• 2021

This study presented techno-economic analysis of a 500 MWe oxy-coal power plant with CO2 capture. The power plant included a circulating fluidized-bed (CFB), ultra-supercritical steam turbine, flue gas conditioning (FGC), air separation unit (ASU), and CO2 processing unit (CPU). The dry flue gas recirculation (FGR) was used to control the combustion temperature of CFB. One FGR heat exchanger, one heat exchanger for N2 stream exiting ASU, and a heat recovery from CPU compressor were considered to enhance heat efficiency. The decrease in the temperature difference (ΔT) of the FGR heat exchanger that means the increase in heat recovery from flue gas enhanced the electricity and exergy efficiencies. The annual cost including the FGR heat exchanger and FGC cooling water was minimized at ΔT = 10 ℃, where the electricity efficiency, total capital cost, total production cost, and return on investment were 39%, 1371 M$, 90 M$, and 7%/y, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.10
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• pp.1407-1413
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• 2005

An experiment was conducted in order to assess the effect of level of RDP:UDP ratio and level of feeding concentrate on milk yield, milk composition and nutrient utilization in lactating crossbred cattle. Twenty four medium producing (-10 kg/d, 45 to 135 days postpartum) lactating crossbred cows were divided into four groups of six animals each in a 2${\times}$2 factorial completely randomized design. The cows in group 1 were fed concentrate mixture I containing 59:41 RDP:UDP ratio (low UDP) at normal plane (LUDP+NP), in group 2 were fed low UDP ration at 115% of NRC (1989) requirements (LUDP+HP), whereas cows in group 3 were fed concentrate mixture II containing 52:48 RDP:UDP ratio (high UDP) at normal plane (HUDP+NP) and in group 4 were fed high UDP ration at 115% of NRC (1989) requirements (HUDP+HP). Green jowar was fed ad libitum as the sole roughage to all the animals. The experimental feeding trial lasted for 105 days. The total dry matter intake (DMI), DMI/100 kg body weight, DMI/kg $W^{0.75}$, digestibilities of DM, OM, CP, CF, EE and NFE and intakes of TDN and DCP did not differ significantly among the different groups and also due to both UDP level and plane of nutrition and also due to their interaction. The total dry matter intake varied from 145 g in group 1 (LUDP +NP) to 152.57 g/kg $W^{0.75}$ in group 2 (LUDP+HP) diet. However, increase in milk yield with increased UDP level and also with increased plane of nutrition was observed consistently throughout the experimental period. The average milk yield was 7.66, 8.15, 8.64 and 9.35 kg in groups 1, 2, 3 and 4, respectively and there was no significant difference in milk yield among different groups of cows. The overall daily average milk yields in cows fed with low and high UDP diets were 7.91 and 8.99 kg, respectively and at normal and higher plane of feeding the milk yields were 8.15 and 8.75 kg/day, respectively. Thus, there was 13.65% increase in milk yield due to high UDP level and 7.36% due to higher plane of feeding. The daily 4% FCM yields were 9.20 kg for low UDP diet and 10.28 kg for high UDP diet, whereas it was 9.11 kg at normal plane of feeding and 10.37 kg at higher plane of feeding. Fat yields for the corresponding treatment groups were 0.37, 0.43, 0.41 and 0.48 kg, respectively. The 4% FCM yield and also fat yield did not differ significantly among different dietary treatments and also due to UDP level and plane of nutrition, however, 4% FCM yield was increased by 11.74% with high UDP level and 13.83% with higher plane of feeding. The values for total solids, fat, lactose, solids-not-fat and gross energy contents in milk differed significantly (p<0.05) among the different groups and were significantly (p<0.05) higher in milk of cows fed LUDP+HP diet followed by HUDP+HP diet. Total solids (14.65 and 13.83%), lactose (5.44 and 4.92%), solids-not-fat (9.44 and 8.83%) and gross energy (887 and 838 kcal/kg) of milk decreased significantly (p<0.05) with increased UDP level while total solids (13.84 and 14.64), fat (4.84 and 5.36%) and gross energy (832 and 894 kcal/kg) increased significantly (p<0.05) with increase in plane of feeding. Gross and net energetic efficiencies and also gross and net efficiencies of nitrogen utilization for milk production were not significantly different among different groups and also were not affected significantly due to either UDP levels or plane of feeding. Results of the present study suggest that, increasing UDP level from 41% to 48% of CP in concentrate mixture and also increasing plane of feeding from normal (100%) to 115% of NRC requirements maintain a consistently higher milk production.

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.4
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• pp.271-280
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• 1994

The aim of this experiment was to investigate the effects of fertilizing mineral nitrogen on dry matter yield of Reed canarygrass and also to estimate proper levels of fertilizing nitrogen when uncultivated rice paddy rapidly increased these days, was used for the production if Reed canarygrass. \ulcornerhe results are as follows. 1. Relative dry matter according to cutting frequency was appeared the highest at the 2nd cut for 3 and 4 cutting frequencies, and the 3rd cut for 5 cutting frequency. Those were 43.1, 34.0 and 34.1 % respectively. 2. When using only phosphrous and potassium, the average dry matter per year and ha was between 9.0 and 12.0 tons(3, 4 and 5 cutting frequency) and the highest dry matter was shown at 5 cutting frequency. 3. In accordance to the increase in the fertilization of nitorgen, the yield of dry matter was increased and, when 30 kg/ha/cut of mineral nitrogen was added, the biggest increase rate per added nitrogen for dry matter yield per year compared to that of no fe~tilization of nitrogen was recorded and it was 2.7, 3.3, and 3.4 tons/ ha for 3, 4 and 5 cutting frequencies respectively. 4. The efficiencies of mineral nitrogen on dry matter yield(DM kg/N kg) were the highest when 30kg nitrogen was applied particularly in 3, 4 and 5 cutting frequencies(29.7, 27.2, 22.8 DM kg/N kg). It recorded the highest of all the treatments. The efficiency was actually decreased in higher application of mineral nitrogen. The total nitrogen yield efficiency was the highest in 30kg(0.45kg and 0.48kg at 4 and 5 cutting frequency) and 60kg fertilization/ha/cut (0.46kg at 3 cuting frequency) and the decreased efficiencies appeared at fertilization of higher nitrogen. 5. Economical borden of mineral nitrogen fertilization were between 199.2 and 243.3kglha at 3 cutting frequency, between 253.4 and 295.9kg at 4 cutting frequency and between 302.2 and 361.3kg at 5 cutting frequency. 6. Under the condition of this experiment, the cutting frequency leading the potential production at maximum was 3 cutting frequency. At 3 cutting frequency, the efficiency of nitrogen utilization was higher and 15 or 16 tons of dry matter was obtained which is a level of economical border at fertilization between 200 and 240kglha. It wrs possible to obtain the maximal dry matter yield(l7 tonslha) at fertilization of lower level than 400kgl ha.