Fabrication and Interface Structural Behavior of Mg/Al Thickness-Oriented Bonding Sheet via Direct Extrusion

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.

Archean basement components and their multiple metamorphic overprintings of the Rangnim Massif in the northern part of the Korean Peninsula

Lei Zhao,Mingguo Zhai,Chang-Whan Oh,Yanbin Zhang,Peng Peng 대한지질학회 2019 대한지질학회 학술대회 Vol.2019 No.10

Nitrification Efficiency in Fixed Film Biofilters using Different Filter Media in Simulated Seawater Aquarium 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

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.

The evolution of the Pyongnam basin: Its relationship with the adjacent basins and tectonic implications

Peng Peng,Mingguo Zhai,Jong-Hyok Yang,Chang-Whan Oh,Hyon-Uk Pak,Yanbin Zhang,Lei Zhao,Zhiyue Zhang,Fengbo Sun 대한지질학회 2019 대한지질학회 학술대회 Vol.2019 No.10

Protein Removal by a Foam Fractionator in Simulated Seawater Aquaculture System

Peng, Lei,Oh, Sung-Yong,Jo, Jae-Yoon Korea Institute of Ocean ScienceTechnology 2003 Ocean and Polar Research Vol.25 No.3

Effects of different operating factors including superficial air velocity (SAV), hydraulic residence time (HRT), protein concentration, and foam overflow height on protein removal by a foam fractionator in simulated seawater aquaculture system were investigated. This experiment was conducted on batch and consecutive modes at different combinations of the affecting factors. The foam fractionator had a diameter of 20cm and a height of 120cm and the experiment was conducted with synthetic wastewater. In 5 consecutive trials, protein concentrations in culture tank water decreased faster when the foam fractionator was operated at higher SAVs and lower HRTs. In batch trials, protein removal rates increased with an increase in SAV but decreased with an increase in URT. Higher protein concentrations in the bulk solution resulted in higher protein removal rates. Protein concentrations in the collected foam condensates increased but the foam overflow rates decreased with the increase of foam overflow heights. The results of this experiment indicate that foam fractionation would be an effective way for protein removal in seawater aquaculture systems and the performance of the foam fractionator depends largely on the operating parameters, especially SAV.

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.

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.

Performance of a Foam Fractionator in a Lab-scale Seawater Recirculating Aquaculture System

Peng, Lei,Jo, Jae-Yoon 한국수산학회 2003 Fisheries and Aquatic Sciences Vol.6 No.4

The performance of a foam fractionator to remove TAN, NO2, NO,, TSS, protein, and Pod-P at different superficial air velocities and foam overflow heights was evaluated in a lab-scale seawater recirculating system for culture of Korean rockfish (Sebastes schlegeli). The foam overflow rates increased with the increase of superficial air velocities, but decreased with the increase of foam overflow heights. Concentrations of all the water quality variables in the foam condensates increased with the increase of foam overflow height, but decreased with the increase of superficial air velocities. TSS, protein, and phosphate enrichment factors were within the range of 6.4-39.4, 1.6-7.3 and I .2-3.9, respectively. Low values of TAN, NO2, and NO3 enrichment factors were obtained and they indicate that foam fractionation is not an effective way to remove dissolved inorganic nitrogen. The calculated maximum daily removal values for TSS and protein were 10.9 and 1.4 g, respectively.

Analysis of Topic Evolution in Educational Data

Lei Peng,Kwankamol Nongpong,Paitoon Porntrakoon 대한전자공학회 2023 IEIE Transactions on Smart Processing & Computing Vol.12 No.2

Analyzing the developing trends of educational data has always been an important issue. However, it is challenging to do it manually because of the data expansion in recent years. A topic evolution-analyzing framework, comprised of a data crawling module and a topic-processing module, is proposed to solve this problem. The Chongqing Three Gorges Medical College of China was used as a case for the experiment, and the framework was implemented using Python language. First, the data were obtained from the website, and its format was reorganized, which is appropriate to be fed into the topic-processing module. Subsequently, all topics were obtained and interpreted as several related phrases. Finally, the topic evolution was obtained over years and months. This work can help education organizations with their historical information summarization, contributing to their development planning and providing academic support to the decision-makers.

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.