고변이 음성훈련과 저변이 음성훈련이 중국인 초급 학습자의 억양 지각에 미치는 영향 -억양의 문법적 기능과 감정 및 태도의 전달 기능을 중심으로-

가맹맹 ( Jia¸ Mengmeng ) 국제한국어교육학회 2020 한국어 교육 Vol.31 No.3

This study analyzes the effects of high- and low-variability phonetic training on learners’ perception of Korean intonation. The participants were twenty Chinese primary learners studying Korean as a foreign language; they were and divided into two groups. The experiment consisted of a pretest, five exercises, a post-test, and a generalization test. The results are as follows. First, high- and low-variability phonetic training have the same effect on increasing the accuracy of learners’ perceptions of the grammatical function of intonation. Second, both high- and low-variability phonetic training are needed to improve the accuracy of primary learners’ perceptions of the emotional/attitudinal function of intonation. Because high-variability phonetic training can compensate for the key disadvantage of low-variability phonetic training, namely that learners find it difficult to master various intonation patterns.; and On the other hand, low-variability phonetic training can compensate for the key disadvantage of high-variability phonetic training, namely that the effect is not stable. (Seoul National University)

Graphene oxide nanosheets to improve permeability and selectivity of PIM-1 membrane for carbon dioxide separation

Mengmeng Chen,Faizal Soyekwo,Qiugen Zhang,Chuan Hu,Aimei Zhu,Qinglin Liu 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-

Polymers of intrinsic microporosity (PIMs) have attracted increasing interest in gas separation membranes due to their high permeability. However, the moderate selectivity limits their wide applications in CO2 separation. Herein we report a facile strategy to improve simultaneously the permeability and CO2 selectivity of PIMs membrane using the prepared PIM-1/graphene oxide (GO) nanosheets mixed matrix membrane. The GO nanosheets improves the hydrophilicity and surface roughness of PIM-1 membrane whereas the uniform assembly of GO nanosheets in the PIM-1 matrix creates the hydrophilic/hydrophobic microphase segregation in the membrane. The as-prepared mixed matrix membrane is also very porous and has a pore size of about 0.78 nm. The combination of these properties significantly contributes to the enhancement of the gas separation performance of PIM-1 membrane, with the resultant membrane exhibiting an exceptionally high CO2 permeability of up to 6169 barrer as well as a high CO2/N2 selectivity of 123.5, which is more than 7 times that of the pure PIM-1 membrane. The developed PIM-1/GO mixed matrix membrane should have a wide application in the CO2 separation.

Alterations in antioxidant function and cell apoptosis in duck spleen exposed to molybdenum and/or cadmium

Mengmeng Zhang,Junrong Luo,Caiying Zhang,Huabin Cao,Bing Xia,Guoliang Hu 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.2

To investigate the effects of molybdenum (Mo) and/or cadmium (Cd) on antioxidant function and the apoptosis-related genes in duck spleens. Sixty healthy 11-day-old ducks were randomly divided into six groups of 10 ducks (control, low Mo group, high Mo, Cd, low Mo + Cd, and high Mo + Cd groups). All were fed a basal diet containing low or high dietary doses of Mo and/or Cd. Relative spleen weight, antioxidant indices, apoptosis-related gene mRNA expression levels, and ultrastructural changes were evaluated after 120 days. The results showed that the relative spleen weight decreased significantly in the high Mo + Cd treatment group which compared with control group. Malondialdehyde levels increased and xanthine oxidase and catalase activities decreased in the Mo and/or Cd groups compared with levels in the control group. Bak-1 and Caspase-3 expressions were upregulated in the high Mo + Cd group, while Bcl-2 was downregulated. In addition, mitochondrial crest fracture, swelling, vacuolation, deformed nuclei, and karyopyknosis in both Mo + Cd treated groups were more severe than in the other groups. The results suggest that Mo and/or Cd can induce oxidative stress and apoptosis of spleen via effects on the mitochondrial intrinsic pathway. Moreover, the results indicate the two elements have a possible synergistic relationship.

An Approach on Automatic Tracking and Predicting of Satellite Cloud Clusters Based on Active Contour

Mengmeng Cui,Yong Huang,Shengjun Xue,Jin Wang 보안공학연구지원센터 2012 International Journal of Hybrid Information Techno Vol.5 No.2

Wideband Tri-band Filter Design using Stepped-impedance Stub Resonators

Mengmeng Cui,Yun Liu,Shengjun Xue,Jin Wang 보안공학연구지원센터 2013 International Journal of Hybrid Information Techno Vol.6 No.5

Assessment of Myocardial Bridge by Cardiac CT: Intracoronary Transluminal Attenuation Gradient Derived from Diastolic Phase Predicts Systolic Compression

Mengmeng Yu,Yang Zhang,Yuehua Li,Minghua Li,Wenbin Li,Jiayin Zhang 대한영상의학회 2017 Korean Journal of Radiology Vol.18 No.4

Objective: To study the predictive value of transluminal attenuation gradient (TAG) derived from diastolic phase of coronary computed tomography angiography (CCTA) for identifying systolic compression of myocardial bridge (MB). Materials and Methods: Consecutive patients diagnosed with MB based on CCTA findings and without obstructive coronary artery disease were retrospectively enrolled. In total, 143 patients with 144 MBs were included in the study. Patients were classified into three groups: without systolic compression, with systolic compression < 50%, and with systolic compression ≥ 50%. TAG was defined as the linear regression coefficient between intraluminal attenuation in Hounsfield units (HU) and length from the vessel ostium. Other indices such as the length and depth of the MB were also recorded. Results: TAG was the lowest in MB patients with systolic compression ≥ 50% (-19.9 ± 8.7 HU/10 mm). Receiver operating characteristic curve analysis was performed to determine the optimal cutoff values for identifying systolic compression ≥ 50%. The result indicated an optimal cutoff value of TAG as -18.8 HU/10 mm (area under curve = 0.778, p < 0.001), which yielded higher sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy (54.1, 80.5, 72.8, and 75.0%, respectively). In addition, the TAG of MB with diastolic compression was significantly lower than the TAG of MB without diastolic compression (-21.4 ± 4.8 HU/10 mm vs. -12.7 ± 8 HU/10 mm, p < 0.001). Conclusion: TAG was a better predictor of MB with systolic compression ≥ 50%, compared to the length or depth of the MB. The TAG of MB with persistent diastolic compression was significantly lower than the TAG without diastolic compression.

Improved SVR Method for Predicting the Cutting Force of a TBM Cutter Using Linear Cutting Machine Test Data

Mengmeng Hu,Biao Li,Bo Zhang,Ruirui Wang,Lei Chen 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11

This research introduces a support vector regression (SVR) method to predict the cutting forces acting on the constant cross section (CCS) disc cutter, including the normal force (FN) and rolling force (FR), based on linear cutting machine (LCM) test data. To improve the prediction effect, an improved SVR-Outlier Detection (SVR-OD) method and an Additional Input Variable (AIV) method are proposed. After removing the outliers, 148 typical LCM test samples form the training set. Here, 70 samples from the Hangzhou No.2 Water Supply Channel constitute the test set. The prediction results show that the Root-mean-squared Relative Error (RMRE) values of the normal force and rolling force are 19.5% and 24.8%, respectively, and the corresponding determination coefficients are 0.845 and 0.807, respectively. For the prediction of the peak cutting force with an important reference to tunnel boring machine (TBM) design, the proportions of samples with an Absolute Relative Error (ARE) value of less than 20% for FN and FR are 9/10 and 7/7, respectively. The above prediction results are better than those of the common SVR method; thus, the developed method can effectively simulate the cutting force required by a rock mass with good integrity. The cutting force prediction using LCM test data is feasible and practical. In addition, the comparison of the prediction results between the improved SVR and common SVR methods shows that the improved SVR-OD and AIV methods play an active role in improving the prediction accuracy of the SVR method.

Output Feedback Stabilization of Stochastic Nonlinear Time-varying Delay Systems with Unknown Output Function

Mengmeng Gao,Junsheng Zhao,Jianwei Xia,Zong-Yao Sun 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.9

This paper addresses the problem of output feedback stabilization for stochastic nonlinear time-varying delay systems with an unknown output function. A remarkable feature of the system to be considered is the simultaneous presence of a continuous unknown sensitivity function and the stochastic disturbances, which have not been treated together before. A new observer is designed by using a dynamic gain without using the information on unknown time-varying delay and nonlinearities. With the aid of the observer, an output feedback controller is constructed by the stochastic double-domination method, where two gains are used to handle the unknown output function and nonlinearities. The performance of the system is analyzed in detail via two integral Lyapunov functions. Finally, the efficiency of the control strategy is illustrated by a simulation example.

Merge

Mengmeng Xiu 한국콘텐츠학회 2013 ICCC International Digital Design Invitation Exhib Vol.2013 No.-

A murine periodontitis model using coaggregation between human pathogens and a predominant mouse oral commensal bacterium

Mengmeng Liu,최영님 대한치주과학회 2022 Journal of Periodontal & Implant Science Vol.52 No.2

Purpose: C57BL/6 mice, which are among the most common backgrounds for genetically engineered mice, are resistant to the induction of periodontitis by oral infection with periodontal pathogens. This study aimed to develop a periodontitis model in C57BL/6 mice using coaggregation between human pathogens and the mouse oral commensal Streptococcus danieliae (Sd). Methods: The abilities of Porphyromonas gingivalis ATCC 33277 (Pg33277), P. gingivalis ATCC 49417 (Pg49417), P. gingivalis KUMC-P4 (PgP4), Fusobacterium nucleatum subsp. nucleatum ATCC 25586 (Fnn), and F. nucleatum subsp. animalis KCOM 1280 (Fna) to coaggregate with Sd were tested by a sedimentation assay. The Sd-noncoaggregating Pg33277 and 2 Sd-coaggregating strains, PgP4 and Fna, were chosen for animal experiments. Eighty C57BL/6 mice received oral gavage with Sd once and subsequently received vehicle alone (sham), Fna, Pg33277, PgP4, or Fna+PgP4 6 times at 2-day intervals. Mice were evaluated at 5 or 8 weeks after the first gavage of human strains. Results: Fnn, Fna, and PgP4 efficiently coaggregated with Sd, but Pg33277 and Pg49417 did not. Alveolar bone loss was significantly higher in the PgP4 group at both time points (weeks 5 and 8) and in all experimental groups at week 8 compared with the sham group. The PgP4 group presented greater alveolar bone loss than the other experimental groups at both time points. A higher degree of alveolar bone loss accompanied higher bacterial loads in the oral cavity, the invasion of not only PgP4 but also Sd and Fna, and the serum antibody responses to these bacteria. Conclusions: Periodontitis was successfully induced in C57BL/6 mice by oral infection with a P. gingivalis strain that persists in the oral cavity through coaggregation with a mouse oral commensal bacterium. This new model will be useful for studying the role of human oral bacteria-host interactions in periodontitis using genetically engineered mice.