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RISS 인기검색어
- 검색키워드
- 저자 : Peng Lei (검색결과 212 건)
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Lei Gao,Feng Li,Ye Wang,Xing Mao Xiao,Peng Da Huo 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8
Solid-state bonding of heterogeneous materials is one of the effective ways to achieve light weight. An extrusion formingprocess for Mg/Al thickness-oriented bonding sheet was carried out. Due to triaxial compressive stress in the extrusion container,the AZ31 and AA6061 billets were deformed and the bonding and forming of Mg/Al thickness-oriented sheet can berealized by this method. The observation results of the bonding position by using XRD, SEM and EDS showed that: at theforming temperature with 360–420 °C, it had a good bonding interface, and the width of the transition layer increased withthe increase of the forming temperature. The presence of brittle intermetallic compounds in the transition layer indicated thatmetallurgical bonding had occurred at the interface. Considering all factors comprehensively, when the forming temperaturewas 390 °C, the bonding quality was appropriate. Its tensile-shear strength was 42 MPa, the width of the interface transitionlayer was about 10 μm, and the microhardness was about 164.3 HV. This method provided scientific guidance and technicalreserves for green forming of Mg/Al sheets.
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Chemical Budgets in Intensive Carp Ponds
Peng, Lei,Oh, Sung-Yong,Jo, Jae-Yoon 한국수산학회 2003 Fisheries and Aquatic Sciences Vol.6 No.4
Budgets for water, nitrogen, and chemical oxygen demand (COD) were determined in two 0.012 ha earthy-bottom ponds stocked with Israeli strain common carp at an initial stocking density of 20 fish/m3. Total ammonia nitrogen (TAN) concentrations increased continuously but later decreased in pond A as a consequence of high nitrification. COD concentrations increased during the experimental period due to the accumulation of feed input. Nutrient budgets showed that feed represented 94-95% of nitrogen input and about 99% of organic matter input. Fish harvest accounted for 40% of nitrogen and organic matter input. Seepage and water exchange removed 15-17% of nitrogen input but only 1-2% of organic matter. Draining of the ponds removed 20-26% of input nitrogen, mostly in inorganic forms, but removed only minus organic matter. Fish and water column respiration accounted for 39% of organic matter input, and benthic respiration accounted for 7-1 2% of organic matter input. No significant change of nitrogen and organic matter in both pond bottoms were found during the three-month growth period. The unrecovered input nitrogen, about 6.3- 13%, was lost through denitrification and ammonia volatilization. On a dry matter basis, fish growth removed 31% of total feed input and left 69% as metabolic wastes.
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Lei Peng,조재윤,Sung-Yong Oh 한국해양과학기술원 2003 Ocean and Polar Research Vol.25 No.3s
Performance of a laboratory scale closed seawater recirculating aquaculture system was evaluated. Twenty-kg of Korean rockfish (130 fish) with an average body weight of 153.8 g was stocked. Over a 107-day culture period, fish reached final density of 51.7 kg/m3 (initial density, 33.3 kg/m3) on the basis of the culture tank volume. On a daily basis, added water amounted to 3.4% of the total water volume in the system. Total ammonia nitrogen (TAN) concentrations were below 1 mg/l and nitrite nitrogen (NO2-N) concentrations were within the range of 1-3 mg/l on most sampling days. TAN was removed from bead and sand filters and it was removed or produced in the sedimentation basin. Basically, NO2-N was removed in the bead and sand filters, while it was either removed or produced in the sedimentation basin. Nitrate nitrogen (NO3-N) was produced in the bead filters and removed from the sand filter and sedimentation basin. The foam fractionator performed well in the recirculating system. The maximal daily removal values for total suspended solids (TSS) and protein were 10.9 g and 1.4 g, respectively. Whole water quality parameters were within the levels commonly recommended for fish culture on most of the sampling days. However, further studies are needed to evaluate the commercial feasibility of this system because of the small-scale system used in present experiment. At least, the present study still provides some basic information for further studies of this kind of system.
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Performance of a Recirculating Aquarium System for the Culture and Holding of Marine Fish
Lei Peng,조재윤 한국수산과학회 2004 Fisheries and Aquatic Sciences Vol.7 No.2
To supply fresh and quality quarantined seafood in live seafood specialty restaurants, facilities for short-term culture or holding of live marine fish and shellfish are a necessity. In this study, the performance of a simple recirculating aquarium system for the culture and holding of marine fish was evaluated. The aquarium system consisted of a culture tank, a foam fractionator for solids removal, and a Styrofoam bead filter for nitrification and solids trapping. In the first trial, the aquarium was stocked with a total of 12kg Korean rockfish, which were fed approximately 0.5% of the total fish body weight daily. During the 2-month culture period, total ammonia nitrogen (TAN) and nitrite nitrogen (NO2-N) concentrations remained below 1mg/L and 2mg/L, respectively. The chemical oxygen demand (COD) fluctuated between 13.6 and 31.2mg/L on selected sampling days. The total suspended solids (TSS) removed by the foam fractionator was between 2.7 and 4.6g daily. The Styrofoam bead filter not only reduced TAN and NO2-N in the culture tank water, but also trapped solids equivalent to 8.3-26.7% of the weight of feed supplied. In Trial 2, 30kg of live fish were held in the aquarium without feeding for a 24-hour period and the water quality parameters were monitored. TAN and NO2-N concentrations first increased and then decreased to around 0.3 mg/L. These results demonstrate that the recirculating aquarium system is a functional option for the short-term culture or holding of marine fish.
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Removal of Total Suspended Solids by a Foam Fractionator in a Simulated Seawater Aquaculture System
Peng, Lei,Jo, Jae-Yoon The Korean Society of Fisheries and Aquatic Scienc 2003 韓國養殖學會誌 Vol.16 No.4
In a simulated seawater aquaculture system, effects of different operating factors like the superficial air velocity (SAY), hydraulic residence time (HRT), protein concentration and foam overflow height on the removal of total suspended solids (TSS) by a foam fractionator, with 20 cm diameter and 120 cm height, were investigated. This experiment was performed on batch and consecutive modes for different combinations of the tested factors, using synthetic wastewater. In 5 consecutive trials, TSS concentration in culture tank water decreased faster, when the foam fractionator was operated at higher SAV and lower HRT. In batch trials, with increasing SAV, TSS removal rate increased, but decreased with increasing HRT. Higher protein concentration in the bulk solution resulted in higher TSS removal rate. TSS concentration in the collected foam condensates increased but the foam overflow rate decreased with increasing foam overflow height. Foam fractionation was effective for removing TSS in seawater aquaculture systems and its performance largely depended on the operating parameters, especially superficial air velocity.
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Peng, Lei,Jo, Jae-Yoon The Korean Society of Fisheries and Aquatic Scienc 2003 韓國養殖學會誌 Vol.16 No.4
Nitrification efficiency of fixed film biofilters with sand, loess bead, and styrofoam bead in biofilter columns of 1-m height and 30 cm width was studied. Synthetic wastewater was continuously supplied to the culture tank to maintain total ammonia nitrogen (TAN) concentration in the inflow water at around 8 mg/L. The hydraulic loading rate was set at 200 ㎥/$m^2$/day. TAN conversion was stabilized after about 90 day conditioning for all the selected filter media but with net accumulations of nitrite. On the volumetric basis, conversion rates of TAN and nitrite were the highest in styrofoam bead filter. Mean volumetric TAN conversion rates in the final samples were 682, 269, and 79 g TAN/㎥/day in the styrofoam bead, sand and loess bead filters, respectively. Low gravity and cost of styrofoam bead render the handling easier and more cost-effective.
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Peng, Lei,Oh, Sung-Yong,Jo, Jae-Yoon Korea Institute of Ocean ScienceTechnology 2003 Ocean and Polar Research Vol.25 No.3
Nitrification performance of fixed film biofilters using coarse sand, loess bead, or styrofoam beads in biofilter columns 1 meter high and 30cm in diameter were studied at different hydraulic and organic matter loading rates. Synthetic wastewater was supplied to the culture tank in order to maintain desired TAN concentrations in inlet water to biofilters. All the biofilters were conditioned 5 months before start of sampling. TAN and $NO_2-N$ conversion rates increased with an increase in the hydraulic loading rate (HLR). However, the improvement in biofilter performance was not linearly correlated to HLR in styrofoam bead filters. This is mainly due to the characteristics of the styrofoam beads used. TAN conversion rates of sand filters increased with the increase of HLR up to $200m^3/m^2$. per day. No increase in the TAN conversion rate was observed at the highest HLR since flooding on the media surface took place. HLR had a significant impact on the TAN conversion rates in loess bead filter up to the highest HLR tested (P<0.05). TAN conversion rates were much less at organic matter loading rates of 9 and 18kg $O_2/m^3$ per day than those without the addition of organic matter in styrofoam bead filters. The addition of glucose resulted in a reduction of the TAN conversion rate from 540 to 284g $TAN/m^3$ per day. No significant difference of TAN conversion rates between the two organic matter loading rates was found (p<0.05). This indicates that the impact of organic matter on nitrification becomes less and less sensitive with an increase in the COD/TAN ratio. At an organic matter loading rate of 9kg $O_2/m^3$. per day, a great reduction of TAN conversion rates was observed in sand filters and loess bead filters. Clearly, organic matter can be one of the most Important Impacting factors on nitrification. $NO_2-N$ conversion rates showed a similar trend for TAN. Based on the TAN and nitrite conversion rates, styrofoam beads showed the best performance among the three filter media tested. Also, the low gravity and price of styrofoam beads make the handling easier and more cost-effective for commercial application. The results obtained at the highest organic matter loading rates can be used in the biofilter design in recirculating aquaculture system.
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Peng, Lei,Oh, Sung-Yong,Jo, Jae-Yoon Korea Institute of Ocean ScienceTechnology 2003 Ocean and Polar Research Vol.25 No.4
Performance of a laboratory scale closed seawater recirculating aquaculture system was evaluated. Twenty-kg of korean rockfish (130 fish) with an average body weight of 153.8g was stocked. Over a 107-day culture period, fish reached final density of $51.7kg/m^3$ (initial density, $33.3kg/m^3$) on the basis of the culture tank volume. On a daily basis, added water amounted to 3.4% of the total water volume in the system. Total ammonia nitrogen (TAN) concentrations were below 1mg/l and nitrite nitrogen $(NO_2-N)$ concentrations were within the range of 1-3mg/l on most sampling days. TAN was removed from bead and sand filters and it was removed or produced in the sedimentation basin. Basically, $NO_2-N$ was removed in the bead and sand filters, while it was either removed or produced in the sedimentation basin. Nitrate nitrogen $(NO_3-N)$ was produced in the bead filters and removed from the sand filter and sedimentation basin. The foam fractionator performed well in the recirculating system. The maximal daily removal values for total suspended solids (755) and protein were 10.9g and 1.4g, respectively. Whole water quality parameters were within the levels commonly recommended for fish culture on most of the sampling days. However, further studies are needed to evaluate the commercial feasibility of this system because of the smallscale system used in present experiment. At least, the present study still provides some basic information for further studies of this kind of system.
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