• Title/Summary/Keyword: Vietnam National University

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Antimicrobial and Hemolytic Activity of Oriental Medicinal Herbs (한약재의 항균 활성 및 인간 적혈구 용혈 활성)

  • Ryu, Hee-Young;Ahn, Seon-Mi;Shin, Yong-Kyu;Sohn, Ho-Yong
    • Microbiology and Biotechnology Letters
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    • v.38 no.2
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    • pp.190-197
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    • 2010
  • To develop the safe and natural antimicrobial agents, the 68 ethanol extracts from the 61 different kinds of oriental herbal medicine were prepared and their antimicrobial activities were evaluated. The herbal medicine used were from China (46 kinds), South Korea (14 kinds), North Korea (5 kinds) and Vietnam (3 kinds), respectively, and the root (27 species) was popular part in this study. The average water content and extraction ratio for ethanol were 7.10% and 6.75%, respectively. Determination of antimicrobial activity by disc-diffusion assay at 0.5 mg/disc concentration showed that the extract of Angelica tenuissima Nakai (china), Illicium verum, Junci medulla, Rhus javanica L., Salvia miltiorrhiza Bunge and Syzygium aromaticum has strong antimicrobial activities against different food spoilage and pathogenic bacteria and fungi. Determination of MIC and MBC/MFC further showed that the extract of Syzygium aromaticum has MIC of 1.25 mg/mL and MBC/MFC of 1.25~5.00 mg/mL against Listeria monocytogenes, Bacillus subtilis, Staphylococcus epidermidis, Staphylococcus aureus, Salmonella typhimurium, Proteus vulgaris, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Saccharomyces cerevisiae. And, the extract of Junci medulla, Rhus javanica L. and Salvia miltiorrhiza Bunge showed strong antibacterial activities with MIC of 0.08~0.63 mg/mL and MBC/MFC of 0.08~2.50 mg/mL against the tested bacteria except E. coli and P. aeruginosa. In a while, the results of hemolytic activity of 68 different herbal extracts against human red blood cells showed that the extract of Angelica tenuissima Nakai has hemolytic activity at 0.5 mg/mL concentration. Therefore, Illicium verum, Junci medulla, Rhus javanica L., Salvia miltiorrhiza Bunge and Syzygium aromaticum were finally selected for natural antimicrobial resources. Further research on active substances and the mode of action of the selected herbal medicine is necessary.

Export Prediction Using Separated Learning Method and Recommendation of Potential Export Countries (분리학습 모델을 이용한 수출액 예측 및 수출 유망국가 추천)

  • Jang, Yeongjin;Won, Jongkwan;Lee, Chaerok
    • Journal of Intelligence and Information Systems
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    • v.28 no.1
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    • pp.69-88
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    • 2022
  • One of the characteristics of South Korea's economic structure is that it is highly dependent on exports. Thus, many businesses are closely related to the global economy and diplomatic situation. In addition, small and medium-sized enterprises(SMEs) specialized in exporting are struggling due to the spread of COVID-19. Therefore, this study aimed to develop a model to forecast exports for next year to support SMEs' export strategy and decision making. Also, this study proposed a strategy to recommend promising export countries of each item based on the forecasting model. We analyzed important variables used in previous studies such as country-specific, item-specific, and macro-economic variables and collected those variables to train our prediction model. Next, through the exploratory data analysis(EDA) it was found that exports, which is a target variable, have a highly skewed distribution. To deal with this issue and improve predictive performance, we suggest a separated learning method. In a separated learning method, the whole dataset is divided into homogeneous subgroups and a prediction algorithm is applied to each group. Thus, characteristics of each group can be more precisely trained using different input variables and algorithms. In this study, we divided the dataset into five subgroups based on the exports to decrease skewness of the target variable. After the separation, we found that each group has different characteristics in countries and goods. For example, In Group 1, most of the exporting countries are developing countries and the majority of exporting goods are low value products such as glass and prints. On the other hand, major exporting countries of South Korea such as China, USA, and Vietnam are included in Group 4 and Group 5 and most exporting goods in these groups are high value products. Then we used LightGBM(LGBM) and Exponential Moving Average(EMA) for prediction. Considering the characteristics of each group, models were built using LGBM for Group 1 to 4 and EMA for Group 5. To evaluate the performance of the model, we compare different model structures and algorithms. As a result, it was found that the separated learning model had best performance compared to other models. After the model was built, we also provided variable importance of each group using SHAP-value to add explainability of our model. Based on the prediction model, we proposed a second-stage recommendation strategy for potential export countries. In the first phase, BCG matrix was used to find Star and Question Mark markets that are expected to grow rapidly. In the second phase, we calculated scores for each country and recommendations were made according to ranking. Using this recommendation framework, potential export countries were selected and information about those countries for each item was presented. There are several implications of this study. First of all, most of the preceding studies have conducted research on the specific situation or country. However, this study use various variables and develops a machine learning model for a wide range of countries and items. Second, as to our knowledge, it is the first attempt to adopt a separated learning method for exports prediction. By separating the dataset into 5 homogeneous subgroups, we could enhance the predictive performance of the model. Also, more detailed explanation of models by group is provided using SHAP values. Lastly, this study has several practical implications. There are some platforms which serve trade information including KOTRA, but most of them are based on past data. Therefore, it is not easy for companies to predict future trends. By utilizing the model and recommendation strategy in this research, trade related services in each platform can be improved so that companies including SMEs can fully utilize the service when making strategies and decisions for exports.

Effects of Gamma Irradiation on Color Changes and Antioxidative Activities of Caesalpinia sappan L. (감마선 조사에 의한 소목추출물의 색상변화 및 항산화 활성 평가)

  • Kwon, Hyung-Jun;Jung, U-Hee;Park, Hae-Ran;Shin, Dong-Hwa;Jo, Sung-Kee
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.36 no.8
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    • pp.1055-1061
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    • 2007
  • Caesalpinia sappan L. is an indeciduous tree distributed in China, India, Miyanmar and Vietnam. Its heartwood has long been used in oriental folk medicines to treat diseases. In this study, antioxidative activities of Caesalpinia sappan L. and the effect of gamma irradiation on its chemical and biological properties were investigated. The ethyl acetate fraction (EtOAc fr.) of Caesalpinia sappan L. was irradiated with 100 kGy of gamma ray. The dark red color of EtOAc fr. was significantly (p<0.05) removed by irradiation (Hunter L and b values increased and a value decreased). The total phenolic content of EtOAc fr. was 865 mg/g and it was increased to 1195 mg/g by gamma irradiation. DPPH radical and superoxide anion radical scavenging activities and lipid peroxidation inhibitory activity of EtOAc fr. were very high and its activities were also increased by gamma irradiation. EtOAc fr. also inhibited the irradiation-induced DNA damage of lymphocyte as determined by comet assay. In conclusion, EtOAc fr. of Caesalpinia sappan L. extract showed high antioxidative activities in vitro. Furthermore, gamma irradiation on EtOAc fr. ameliorated the color and antioxidative properties. Therefore, it can be suggested that Caesalpinia sappan L. may be a good material for antioxidant function and gamma irradiation may be applied for the improvement of chemical and biological properties of Caesalpinia sappan L.

Southeast Asia and ASEAN in 2016: Disappointing Records and Increasing Uncertainty (동남아와 아세안 2016: 기대와 혼돈 속에 커져가는 불확실성)

  • SHIN, Yoon Hwan
    • The Southeast Asian review
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    • v.27 no.1
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    • pp.95-129
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    • 2017
  • This study surveys and reviews political change, economic performance, and regional cooperation that were carried out in 2016 by Southeast Asian countries and ASEAN. This paper reports that what has followed the inauguration of new governments in Myanmar, the Philippines, Vietnam, and Laos fails to live up to the expectation and optimism that arose in the aftermath of elections and party congresses that took place in the first half of the year. In other countries such as Malaysia, Thailand, and Cambodia, where authoritarian regimes are faced with strong oppositions, the prospects for democratic change worsened to a substantial degree, as schisms and internal strives complicated the opposition camp as a result of instigation and intervention by the authoritarian leaders and their followers. In stable political systems, both democratic and authoritarian, no significant changes that may entail serious political implications were noticed. In 2016, the national economy of almost each and every country continued its slow but steady recovery that had started in 2014 and grew by 5% on the average. For 2017 onward, however, the earlier optimism that it would grow at least as fast dimmed down as uncertainty about the world economy looms larger due to the unexpected win by Donald Trump as U.S. president and the expected 'hard landing' of the Chinese economy around 2018. ASEAN declared the launch of the ASEAN Economic Community (AEC) only one day before the New Year, but its track record looked already bad and unpromising by the end of 2016. ASEAN leaders were tied up by their domestic politics and affairs too tightly to take time off to work seriously to observe the schedule as laid out in the AEC Blueprint 2025. Korea's relationship with Southeast Asian countries and ASEAN was "as good as it gets" in 2016 as ever but could become subject to tough review in the near future, if the Ministry of Foreign Affairs is found out to have been implicated in the ongoing Choi Sun Sil scandal and if the opposition wins the next presidential election to be held by this year.