• International Journal of Internet, Broadcasting and Communication
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• 제15권1호
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• pp.140-144
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• 2023

In recent years, there are so many serious crashes involving coaches, especially the frontal collision occupies 40% of the front of the vehicle, Frontal collisions account for 100% of the front of the vehicle affecting the driver and side-impact collisions that injure the person in the vehicle. Therefore, the research into improving and optimizing the structure is necessary for risk of injury for passengers in frontal accidents. In this paper, we have designed a Shock absorber that can absorb collision energy. Research using HYPERMESH software. to build the finite element model and calculate the meshing to suit the mesh size of 5mm. apply LS-DYNA software to calculate structural strength. In the study, for a vehicle to collide with a hard obstacle occupying 100% of the head of the vehicle. Then, the experimental design method, Minitab is used for find the structural parameters in the design. Improvement results showed that the acceleration of the impact on passengers and the driver is decreased by 55,17%. The mass of texture improvements is reduced by 11%, according to the requirements of European Standards ECE R94.

• The Journal of Asian Finance, Economics and Business
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• 제9권5호
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• pp.285-294
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• 2022

Using the ARDL approach, this study examined the impact of macro factors on Vietnam's stock market in the short and long run from 2010 to 2021. The State Bank of Vietnam and the International Monetary Fund provided time series data for this study. Research results show that in the long run, money supply and exchange rate respectively affect the stock market. The money supply had a positive effect on the VN-Index, while the exchange rate showed the opposite effect. However, the study did not find a relationship between world oil price and interest rates on VN-Index in the long run. On the other hand, in the short term, there are relationships between variables; specifically, interest rates and exchange rates have a negative impact on the VN-Index, while the world oil price and the fluctuation of money supply M2 of the previous one and two months showed an impact in the same direction on this index. The differences in the regression results on the impact of exchange rate and oil price on the VN-Index compared to previous studies come from the characteristics of Vietnam's stock market, with the large capitalization of companies in the oil and gas sector, and the structure of Vietnam's economy with export heavily depends on FDI sector.

• Journal of Ecology and Environment
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• 제42권1호
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• pp.30-42
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• 2018

Background: The southern and eastern parts of the Gobi Desert area are a unique dry ecosystem with a diverse regional desert, semi-desert, and mountain dry steppe flora. This area habitat is located at the overlap of different floristic regions; on its northeast side, Central Asian desert flora is dominating, and on the eastern side, East Asian flora is observed. The comprehensive survey was carried out to find the floral diversity of the medicinal plants on the region. Methods: All recorded species in this study were based on the collected voucher specimens between June and August in the year 2017. Results: We recorded 23 families, 57 genera, and 78 species of vascular plants. The families Asteraceae (15 species), Fabaceae (10 species), and Amaranthaceae (10 species) were represented most in the study area, while Caragana (5 species), Salsola (4 species), and Arnebia (3 species) were the most common genera found. Conclusion: Conservation status for remarkable species was also reviewed based on the literature. Around the study area, 24 species as "sub-endemic," 10 species as "very rare," 4 species as "rare," 1 species as "alien," 13 species as "relict," 10 species as "Red Book," 2 species as "endangered (EN)," 3 species as "vulnerable (VU)," 3 species as "near threatened (NT)," and 2 species as "least concern (LC)" plants are growing.

• 스마트미디어저널
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• 제5권2호
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• pp.42-50
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• 2016

In case of a emergency situation or a natural disaster, a warning notification system is an essential tool to notify at-risk people in advance and provide them useful information to survive the event. Although some systems have been proposed such as emergency alert system using android, SMS, or P2P overlay network, these works mainly focus on a reliable message distribution methods. In this paper, we proposed a novel design and implementation of a personalized warning notification system to help inform not only the at-risk people but also their family and friends about the coming disaster as well as escape plan and survival information. The system consists of three main modules: the user selection module, the knowledge based message generator, and message distribution modules. The user selection module collects the list of people involved in the event and sorts them based on their level of involvement (their location, working position and social relationships). The knowledge based message generator provides each person with a personalized message that is concise and contains only the necessary information for the particular person based on their working position and their involvement in the event. The message distribution module will then find a best path for sending the personalized messages based on trustiness of locations since network failures may exist in a disaster event. Additionally, the system also have a comprehensive database and an interactive web interface for both user and system administrator. For evaluation, the system was implemented and demonstrated successfully with a building on fire scenario.

• 한국분말재료학회지
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• 제31권2호
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• pp.119-125
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• 2024

The n-type Bi_2-xSb_xTe₃ compounds have been of great interest due to its potential to achieve a high thermoelectric performance, comparable to that of p-type Bi_2-xSb_xTe₃. However, a comprehensive understanding on the thermoelectric properties remains lacking. Here, we investigate the thermoelectric transport properties and band characteristics of n-type Bi_2-xSb_xTe₃ (x = 0.1 - 1.1) based on experimental and theoretical considerations. We find that the higher power factor at lower Sb content results from the optimized balance between the density of state effective mass and nondegenerate mobility. Additionally, a higher carrier concentration at lower x suppresses bipolar conduction, thereby reducing thermal conductivity at elevated temperatures. Consequently, the highest zT of ~ 0.5 is observed at 450 K for x = 0.1 and, according to the single parabolic band model, it could be further improved by ~70 % through carrier concentration tuning.

• Steel and Composite Structures
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• 제51권6호
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• pp.679-695
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• 2024

This paper presents a novel technique that combines machine learning (ML) with moth-flame optimization (MFO) methods to predict the axial compressive strength (ACS) of concrete filled double skin steel tubes (CFDST) columns. The proposed model is trained and tested with a dataset containing 125 tests of the CFDST column subjected to compressive loading. Five ML models, including extreme gradient boosting (XGBoost), gradient tree boosting (GBT), categorical gradient boosting (CAT), support vector machines (SVM), and decision tree (DT) algorithms, are utilized in this work. The MFO algorithm is applied to find optimal hyperparameters of these ML models and to determine the most effective model in predicting the ACS of CFDST columns. Predictive results given by some performance metrics reveal that the MFO-CAT model provides superior accuracy compared to other considered models. The accuracy of the MFO-CAT model is validated by comparing its predictive results with existing design codes and formulae. Moreover, the significance and contribution of each feature in the dataset are examined by employing the SHapley Additive exPlanations (SHAP) method. A comprehensive uncertainty quantification on probabilistic characteristics of the ACS of CFDST columns is conducted for the first time to examine the models' responses to variations of input variables in the stochastic environments. Finally, a web-based application is developed to predict ACS of the CFDST column, enabling rapid practical utilization without requesting any programing or machine learning expertise.

• 한국자원식물학회지
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• 제34권1호
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• pp.103-113
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• 2021

본 연구는 무등산국립공원 담양권역의 전체 식물상 및 특기 할만한 식물의 분포를 파악하고 생태계교란 야생식물의 유입요인 및 관리방안을 모색해보기 위해 수행되었다. 조사는 2019년 5월부터 2020년 10월까지 총 8차례에 걸쳐 실시되었다. 무등산국립공원 담양권역의 식물상은 107과 349속 531종 57변종 5아종 10품종 총 603 분류군이 분포하는 것으로 확인하였다. 이는 우리나라 관속식물 총 4,881 분류군의 약 12.33%로 나타났다. 무등산국립공원 담양권역에서 출현한 희귀식물은 총 15 분류군이 관찰되었다. 멸종위기종(CR)은 목련, 위기종(EN)은 댕강나무 등이 출현하였다. 취약종(VU)은 개박하, 나도옥잠화, 땅나리 그리고 주목이 관찰되었다. 무등산국립공원 담양권역의 식물구계학적 특정식물은 50과 73속 81종 3변종 1아종으로 총 85 분류군이 출현하였다. V등급은 승마 등 3분류군, IV등급은 선주름잎, 고로쇠나무, 털조장나무 등 5분류군, III등급은 청시닥나무, 산황나무 등이 관찰되었고, 특산식물은 노각나무, 닥나무, 각시서덜취, 백운산원추리, 병꽃나무, 검팽나무, 진범 등 총 13 분류군으로 파악되었다. 무등산국립공원 담양권역에서 출현한 귀화식물은 미국자리공, 방가지똥 등 16과 36속 45종 총 45 분류군으로 관찰되었고, 귀화율은 7.46%로 나타났으며, 도시화지수는 14.01%로 계산되었다. 생태계교란 야생식물은 돼지풀, 애기수영, 도깨비가지, 및 양미역취 총 4 분류군이 관찰되었다. 신선대억새평전에 생육하는 생태계교란 야생식물인 애기수영에 대한 장기적인 모니터링이 요구되고, 특히 물리적이고 생물학적인 방제가 지속되어야 할 것이다.

• Korean Chemical Engineering Research
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• 제60권4호
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• pp.473-477
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• 2022

본 연구에서는 폐배터리 재활용 공정에서 발생하는 공정폐액 중 리튬 회수를 위한 후보 기술들을 검토하고 상용화 관점에서 해당 공정에 적용 가능한 기술들을 정성적 측면에서 검토하였다. 현재 기술 수준에서 상용화 규모로 적용 가능한 증발법, 침전 및 용매추출 기술이 있다. 증발법의 경우 대규모의 땅을 필요로 하고 농축과정에서의 Li 손실로 낮은 회수율 보여 적용하기 어렵다. 침전의 경우, 상용화되어 있는 기술로 인산의 높은 Li/Na 선택도로 높은 회수율을 보이지만 비싼 인산 사용으로 회수 단계 필요로 공정이 복잡하고 Li 농축과정에서 고체를 다루고 있어 연속운전이 불가능하다는 단점이 있다. 용매추출의 경우, Li/Na 선택도가 높은 저렴한 추출제를 찾는다면 전 단계의 다른 금속 추출 시 사용되고 있는 방법으로 연속운전이 가능하고 Li 농축 시 액체 상태이기 때문에 연속운전이 가능하다는 장점이 있다. 침전기술과 비교하여 유사한 회수율을 보인다면 상용화가 가능성이 가장 높을 것이다.

• 마케팅과학연구
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• 제19권2호
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• pp.27-39
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• 2009

Compulsive consumption is regarded as a global phenomenon that can adversely affect consumer well-being. Although the topic has been studied in different cultural settings, we have seen relatively little theory development and explanations of compulsive behavior Nearly all previous empirical studies attempt to explain this behavior by correlating measures of compulsive behavior with independent variables taken within the same time frame. However, recent developments in social sciences suggest that such a phenomenon may best understood in the context of the person's earlier-in-life experiences. Using the life course paradigm as an overarching framework, the present research extends previous work on this topic. Following hypotheses were drawn from literature review: H1: The earlier in childhood and adolescence a person experiences family dislocation, the greater his or her likelihood of exhibiting compulsive behaviors in adulthood. H2: The earlier in life the young person experienced family dislocation, the greater the number of family disruption events the young person experienced prior entering adulthood years. H3: Family dislocation leads to (a) increased frequency of socio.oriented family communications and (b) decreased frequency of concept-oriented family communication. H4: Young adults who were raised in families characterized by a strong socio-oriented communication structure are more likely to exhibit compulsive consumption tendencies than those who were raised in families characterized by a weak socio-oriented family communication structure. H5: Young adults who were raised in families characterized by a strong concept-oriented communication structure are less likely to exhibit compulsive consumption tendencies than those who were raised in families characterized by a week concept-oriented family communication structure. H6: The relationship between family disruption events experienced during adolescence and perceived stressfulness of these events is moderated by (a) global family support, (b) emotional family support, and (c) material family support. Those reporting higher levels of family support as teenagers are less likely to report experiencing stress due to family disruption events. H7: Perceived stressfulness of family disruption events experienced during adolescent years are associated with compulsive consumption tendencies in early adulthood. H8: The greater the number of family disruption events young adults experienced during their adolescent years the more frequent was their communication about consumption with their peers. H9: The more frequent was the young persons' communication with their peers about consumption during their adolescent years, the more likely they are to report compulsive buying tendencies as young adults. We use a sample of 120 Thai undergraduate students attending classes taught in English as part of a four-year international program. Product-moment correlations, hierarchical regression analysis and partial correlation were used to analyze data. Results of testing hypotheses showed that hypothesis 2, 4, 7 and 9 were supported and hypothesis 1, 3, 5, 6 and 8 were not supported. Our study did not find a significant relationship between the age when a person experienced family dislocation and their compulsive behavior tendencies expressed as young adults. We did not find a significant relationship between family dislocation and family communication structures. But we found a significant positive relationship between socio-oriented communication structure and compulsive buying and a significant relationship between our peer communication and compulsive buying measures. Also we found perceived stressfulness due to the disruptive events to have a significant positive relationship between the perceived stressfulness and compulsive buying. Implications from these findings, limitations of this research and future research suggestions were discussed.