A Multi-device Task Offloading Framework For Energy Optimization In Mobile Edge Computing

Dang Quang Nhat Minh(당꽝녓밍),Myungsik Yoo(유명식) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6

The fast development of mobile-based technologies has utilized resource-hungry mobile applications, such as Augmented Reality (AR), Virtual Reality (VR), vehicular networks, etc. However, the fast development of these applications leads to more complexity and requires more computation resources over time. Mobile Edge Computing (MEC) is introduced that brings computation environment near the end-users to achieve essential requirements such as low energy consumption, low latency, low cost. This paper proposes a task offloading framework to optimize the energy consumption of multi-device in consideration of the edge server computation capacity in MEC environment.

Mixotrophic Cultivation of Marine Alga Tetraselmis sp. Using Glycerol and Its Effects on the Characteristics of Produced Biodiesel

Dang, Nhat Minh,Kim, Garam,Lee, Kisay The Korean Society of Industrial and Engineering C 2022 공업화학 Vol.33 No.2

As a possible feedstock for biodiesel, the marine green alga Tetraselmis sp. was cultivated under different conditions of phototrophic, mixotrophic and heterotrophic cultures. Glycerol, a byproduct from biodiesel production process, was used as the carbon source of mixotrophic and heterotrophic culture. The effects of glycerol supply and nitrate-repletion were compared for different trophic conditions. Mixotrophic cultivation exhibited higher biomass productivity than that of phototrophic and heterotrophic cultivation. Maximum lipid productivity of 55.5 mg L^-1 d^-1 was obtained in the mixotrophic culture with 5 g L^-1 of glycerol and 8.8 mM of nitrate due to the enhancement of both biomass and lipid accumulation. The major fatty acid methyl esters (FAME) in the produced biodiesel were palmitic acid (C16:0), oleic acid (C18:1), linoleic acid (C18:2), and linolenic acid (C18:3). The degree of unsaturation was affected by different culture conditions. The biodiesel properties predicted by correlation equations based on the FAME profiles mostly complied with the specifications from the US, Europe and Korea, with the exception of the cold-filter plugging point (CFPP) criterion of Korea.

Decolorization of organic fertilizer using advanced oxidation process and its application for microalgae cultivation

Nhat Minh Dang,Kisay Lee 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.59 No.-

Advanced oxidation using UV radiation in the presence of H2O2 was applied for decolorization of liquid fertilizer and the resulting liquid fertilizer was utilized to the cultivation of microalga Chlorella vulgaris and biodiesel production. The growth of C. vulgaris was enhanced in decolorized medium. The biomass productivity of C. vulgaris in AOP-treated PAL1 reached 124 mg/L, which was 2.1 times higher than that in original PAL1, 58 mg/L/day. Cellular lipid accumulation was increased in decolorized medium (from 6 to 30%), because fast growing cells consumed nitrogren faster in decolorized medium and thus lipid synthesis was triggered in nitrogen-deficient environment.

A study of life cycle assessment for ocean-based microalgae cultivation and biodiesel production

Dang Nhat MINH,Garam KIM,Kisay LEE 한국생물공학회 2018 한국생물공학회 학술대회 Vol.2018 No.4

Utilization of Organic Liquid Fertilizer in Microalgae Cultivation for Biodiesel Production

Nhat Minh Dang,이기세 한국생물공학회 2018 Biotechnology and Bioprocess Engineering Vol.23 No.4

The utilization of organic liquid fertilizer PAL-1 as the culture medium of the microalga Chlorella vulgaris was investigated for the purpose of biodiesel production. Cell growth and lipid accumulation in PAL-1 were evaluated and compared with those in the artificial medium BG-11. Cells showed mixotrophic growth when utilizing the organic liquid fertilizer PAL-1. The rates of cell growth (0.143 d-1) and N consumption (14.9 mg/L/d) in PAL-1 were almost the same as those in BG-11, under the presence of 2% CO2-enriched aeration and light irradiation. Lipid synthesis was triggered in PAL-1 on day 4, when nitrogen was completely consumed, and the lipid content reached up to 48% thereafter. Lipid productivity could be enhanced using repeated-batch cultivation in which cells were exposed to N limitation repeatedly, and thus lipid synthesis was induced while maintaining a sufficiently high cell density.

A Study On Deep Learning-based Multivariate Resource Estimation With Feature Selection In Cloud Computing

Nhat-Minh Dang-Quang(당꽝녓민),Myungsik Yoo(유명식) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.11

Resource provisioning in cloud computing environment depends on different future resource utilization. Because the resource utilization trend may vary dynamically, we need to estimate the future resource utilization for effective resource provisioning decisions. The problem becomes more challenging since performance indicators for one resource may depend on other resources. This paper proposes a deep learning-based multivariate workload estimation with feature selection for cloud computing environment. First, we use the Pearson correlation method to select the best features as inputs for the multivariate model. Then, we propose to use the bidirectional long short-term memory (Bi-LSTM) to estimate future resource utilization. The results are conducted using a real workload dataset and show that the proposed multivariate Bi-LSTM model outperforms the multivariate LSTM model in prediction accuracy.

Decolorization of organic fertilizer using advanced oxidation process and its application for microalgae cultivation

Dang, Nhat Minh,Lee, Kisay Elsevier 2018 Journal of industrial and engineering chemistry Vol.59 No.-

<P><B>Abstract</B></P> <P>Advanced oxidation using UV radiation in the presence of H<SUB>2</SUB>O<SUB>2</SUB> was applied for decolorization of liquid fertilizer and the resulting liquid fertilizer was utilized to the cultivation of microalga <I>Chlorella vulgaris</I> and biodiesel production. The growth of <I>C. vulgaris</I> was enhanced in decolorized medium. The biomass productivity of <I>C. vulgaris</I> in AOP-treated PAL1 reached 124mg/L, which was 2.1 times higher than that in original PAL1, 58mg/L/day. Cellular lipid accumulation was increased in decolorized medium (from 6 to 30%), because fast growing cells consumed nitrogren faster in decolorized medium and thus lipid synthesis was triggered in nitrogen-deficient environment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Advanced oxidation process (AOP) using UV and H<SUB>2</SUB>O<SUB>2</SUB> was successfully applied to reduce the dark color of liquid fertilizer. </LI> <LI> Comparison of microalgae cultivation was made in the original and AOP-treated liquid fertilizer as a culture medium of microalgae. </LI> <LI> AOP-treated medium resulted in increased biomass concentration and lipid content of <I>Chlorella vulgaris</I> during cultivation time. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Advanced oxidation by UV/H<SUB>2</SUB>O<SUB>2</SUB> was applied for decolorization of liquid fertilizer, and the resulting liquid fertilizer was utilized to the cultivation of microalga <I>Chlorella vulgaris</I> and biodiesel production.</P> <P>[DISPLAY OMISSION]</P>

바이오디젤 생산원료로써 미세조류의 배양을 위한 대체 영양원 사용 기술

당낫민 ( Nhat Minh Dang ),이기세 ( Kisay Lee ) 한국공업화학회 2018 공업화학 Vol.29 No.1

미세조류는 바이오연료 생산을 위한 가장 지속가능하고 장래성이 좋은 생산 원료로 여겨지고 있다. 하지만 최근의 몇몇 전과정평가 연구에 의하면 미세조류 바이오디젤 생산, 특히 배양 단계에 많은 에너지가 소요된다는 단점이 있다. 유기탄소, 질소 및 인과 같은 영양분, 그리고 배양에 필요한 용수 비용이 전체 배양 단계의 80%까지 이를 수 있다. 본 총설에서는 최근 미세조류 배양에 필요한 인공배지의 대체용으로 사용 가능성이 높은 하폐수, 유기비료 연소배가스, 유기성 폐기물 등에 대한 최근의 활용 경향과 사용 전략에 대하여 문한 조사를 통해 요약 및 고찰하였다. Microalgae is considered as one of environmentally sustainable and potential feedstocks to produce biodiesels. However, recent studies on life cycle assessments (LCA) of microalgal buidiesels have shown that energy requirement is not small to produce biodiesel from microalgae, especially during cultivation stage. The costs for carbon sources, nutrients like nitrogen or phosphorous, and water for cultivation can contribute up to 80% of the total medium costs. In the present article, recent trends on the utilization of several promising nutrient sources such as municipal wastewaters, organic fertilizers, combustion exhaust emissions and organic solid wastes were reviewed, and the potential strategies to be used as substitutes of artificial culture media, especially for the biodiesel production, were discussed.

미세조류 탈지세포잔류물의 미생물 배양 및 바이오에너지 생산으로의 재활용

당낫민 ( Nhat Minh Dang ),이기세 ( Kisay Lee ) 한국공업화학회 2021 공업화학 Vol.32 No.5

Microalgae is one of the promising biodiesel feedstock with high growth rates compared to those of terrestrial oil crops. Despite its numerous advantages, biodiesel production from microalgae needs to reduce energy demand and material costs further to go to commercialization. During solvent extraction of microalgal lipids, lipid-extracted algae (LEA) cell residue is generated as an organic solid waste, about 80-85% of original algal biomass, and requires an appropriate recycling or economic disposal. The resulting LEA still contains significant amount of carbohydrates, proteins, N, P, and other micronutrients. This review will focus on recent advancement in the utilization of LEA as: (i) utilization as nutrients or carbon sources for microalgae and other organisms, (ii) anaerobic digestion to produce biogas or co-fermentation to produce CH₄ and H₂, and (iii) conversion to other forms of biofuel through thermochemical degradation processes. Possible mutual benefits in the integration of microalgae cultivation-biodiesel production-resulting LEA with anaerobic digestion and thermochemical conversion are also discussed.

Antimicrobial Activity of Phenolic-Rich Extracts from Mango Seed Kernel on Microorganisms

Tam Dang Thi Thu,Binh Ly Nguyen,Nhan Tran Chi,Loc Nguyen Bao,Phuong Nguyen Nhat Minh 한국미생물·생명공학회 2023 한국미생물·생명공학회지 Vol.51 No.4

Replacing synthetic additives to preserve food products with natural antimicrobial compounds needs to be considered due to public health. In the present study, the phenolic extract from mango seed kernel (MSK) with the total phenolic content (TPC) value of 5300 ± 380 mg gallic acid equivalent (GAE)/L was used for evaluating the antimicrobial properties against five types of bacterial strains, including Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhimurium in vitro. This extract was also used for in situ method on the storage of Pangasianodon hypophthalmus fish fillets. The minimum inhibitory concentration (MIC) values for all tested strains were determined at an average concentration of 1325 mg GAE/L. Furthermore, the minimum bactericidal concentration (MBC) values of E. coli, S. aureus, and S. typhimurium were seen at 5300 mg GAE/L, while the extract did not show eliminations in the growth of the remaining strains. The bacterial inhibition speed of the extract illustrated that the concentration equal MIC value eliminated S. typhimurium growth after 24 h, the 4 times MIC value had remarkable effects on S. aureus growth after the 9 h of incubation, and 24 h of incubation for E. coli, L. monocytogenes, P. aeruginosa. Additionally, the MSK extract could inhibit the growth of P. aeruginosa on fish fillets in 4 days of storage. These results provide important evidence for the utilization of MSK as a natural source of antimicrobial agents in food products.