기후변화 교육을 위한 북극과 남극 가상현실 탐험

류한칭 ( Hanqing Liu ),박경신 ( Kyoung Shin Park ) 한국정보처리학회 2020 한국정보처리학회 학술대회논문집 Vol.27 No.2

환경 문제는 사람들이 직접적으로 보지 못하면 쉽게 이해하기 어렵다. 그리고 오랜 시간 동안 아주 조금씩 환경 파괴가 발생하는 경우가 많기 때문에, 실질적으로 환경 문제를 체감하는 것이 쉽지 않다. 본 연구에서는 몰입형 가상현실 시스템을 이용해서 기후변화의 원인인 지구온난화로 인해 북극과 남극의 바다 빙하가 녹고 있는 문제를 체험할 수 있도록 Melting Sea Ice 를 개발하였다. 사용자들은 몰입형 가상현실 장치를 착용하고 시간의 흐름에 따라 남극 북극 빙하가 녹은 모습과 해빙에 따른 생태 환경의 변화를 직접 돌아다니면서 관찰할 수 있다. 본 연구에서는 Melting Sea Ice 가상 현실 콘텐츠를 통하여 기후 변화로 인한 환경 파괴 문제를 직관적으로 인식시키고 환경 문제를 해결하고자 하는 동기부여를 목적으로 두고 있다.

The Research of Power Frequency Interference in the Acquisition System of SEMG

Hanqing Zhao,Bo You,Yi Liu,Shoutong Tao 보안공학연구지원센터(IJSIP) 2013 International Journal of Signal Processing, Image Vol.6 No.5

Joint Space-time Coding and Power Domain Non-orthogonal Multiple Access for Future Wireless System

( Jin Xu ),( Hanqing Ding ),( Zeqi Yu ),( Zhe Zhang ),( Weihua Liu ),( Xueyan Chen ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.1

According to information theory, non-orthogonal transmission can achieve the multiple-user channel capacity with an onion-peeling like successive interference cancellation (SIC) based detection followed by a capacity approaching channel code. However, in multiple antenna system, due to the unideal characteristic of the SIC detector, the residual interference propagated to the next detection stage will significantly degrade the detection performance of spatial data layers. To overcome this problem, we proposed a modified power-domain non-orthogonal multiple access (P-NOMA) scheme joint designed with space-time coding for multiple input multiple output (MIMO) NOMA system. First, with proper power allocation for each user, inter-user signals can be separated from each other for NOMA detection. Second, a well-designed quasi-orthogonal space-time block code (QO-STBC) was employed to facilitate the SIC-based MIMO detection of spatial data layers within each user. Last, we proposed an optimization algorithm to assign channel coding rates to balance the bit error rate (BER) performance of those spatial data layers for each user. Link-level performance simulation results demonstrate that the proposed time-space-power domain joint transmission scheme performs better than the traditional P-NOMA scheme. Furthermore, the proposed algorithm is of low complexity and easy to implement.

Mechanical Properties and Strengthening Mechanism of Aluminum Matrix Composites Reinforced by High-entropy Alloy Particles

Kaiguang Luo,Shilei Liu,Hanqing Xiong,Yun Zhang,Charlie Kong,Hailiang Yu 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11

1 − 6 wt% Al0.5CoCrFeNihigh-entropy alloy particles (HEAp)/AA1050 aluminum matrix composites (AMCs) were preparedby stir casting process. The effect of HEAp mass fractions on microstructure and mechanical properties of the AMCswas studied. The results showed that with the increase in HEAp, the grains were obviously refined, and the ultimate tensilestrength (UTS) was gradually increased. The AA1050 − 3 wt% HEAp AMCs had the optimum mechanical properties. ItsUTS was 115 MPa and its elongation was 32.1%. The fracture mechanism of composites changed from ductile fracture toquasi-cleavage fracture with more HEAp. A theoretical model for predicting the yield strength of composites was established. The theoretical values were in good agreement with experimental results, and the average error between theoreticaland experimental values was 4.2%.

Cavitation cloud dynamic characteristics of dual-chamber self-excited oscillatory waterjet

Dezheng Li,Yong Kang,Hanqing Shi,Yi Hu,Qi Liu,Hongchao Li,Jincheng Hu,Jiamin Li 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

Aiming to enhance self-excited oscillating cavitation jet performance, the effect of the dual-chamber nozzlestructure on the jet dynamical characteristics was designed and investigated. With high-speed camera technology,the cavitation phenomenon was investigated to analyze the area pattern and shedding period of the cavitation cloudunder different nozzle structures. The results showed that the dual-chamber nozzle significantly improved the jet cavitationstrength, and the cavitation cloud area increased by 76% and decreased the shedding period by 90% comparedwith the single-chamber nozzle. In the upstream chamber, the upper shrinkage ratio had a more drastic effect on thecavitation cloud area and shedding frequency than the lower shrinkage ratio with a more sensitive effect on the sheddingfrequency. In the downstream chamber, the outlet diameter ratio and chamber diameter were more sensitive tothe regulation of cavitation cloud shedding frequency and area, respectively, with the optimal regulation at the outletdiameter ratio of 1 and chamber length of 6 mm. The chamber diameter modulated the cavitation cloud most drasticallywith a comprehensive performance optimum at 12mm, which the area fluctuation reached 76.8%. The resultsprovide a basis for further research and application of dual-chamber nozzles.

The Verification of Physiological Model of SEMG Based on Wavelet Decomposition

Bo You,Shoutong Tao,Yi Liu,Hanqing Zhao 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.5

The decomposition methods of surface electromyogram (SEMG) signals are mainly based on independent component analysis, blind source separation and the neural network. Because actual signals are the decomposition faced to single-guide signals, so the neural network decomposition method has more advantage. In this paper, we improve the composition of neural network based on the generation principle and decomposition significance of SEMG, and use this network to decompose the signal and to obtain a higher accuracy through the experimental data above. Beside, under medium-low shrinkage level the decomposition algorithm can successfully extract the dissemination information of motor unit action potentials in SEMG.

Experimental Study on Crack Propagation of Concrete Under Various Loading Rates with Digital Image Correlation Method

Jingwu Bu,Xudong Chen,Liangpeng Hu,Hanqing Yang,Saisai Liu 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.3

The quantificational exploration of the propagation law of fracture process zone (FPZ) is of great importance to the research on concrete fracture. This paper performed fracture experiments on pre-cracked concrete beams under various loading rates. Digital image correlation (DIC) method was applied to obtain the whole field displacement of concrete in the fracture test. The crack opening displacement (COD) and the evolution of FPZ were determined based on the whole field displacement. The results show that the length of FPZ first increases and then decreases with the development of the effective crack length and the maximum length of FPZ is about 60 mm. It can be found that the length of FPZ corresponding to the peak load decreases with the increase of loading rates. Based on the fictitious crack model, a bilinear softening model was established. According to the proposed model, the mechanical behavior and the propagation law of FPZ were analyzed. The bilinear softening model can reflect the microcrack development and the aggregate interlocking in the FPZ.

Investigating the Influences of Wet Fiber Laser Cutting Upon the Surface Integrity of Nitinol Cardiovascular Stents

Xiaoyu Sun,Xiuting Wei,Zhiyong Li,Deda Lou,Yongqi Wang,Hanqing Liu 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.7

High precision laser cutting with minimal post-treatment is needed in the manufacturing of nitinol cardiovascular stents. This paper carries out a series of cutting experiments of nitinol cardiovascular stents by wet fiber laser cutting to understand the basic process characteristics and to investigate the influences of process parameters (laser power, cutting speed, pulse width, frequency) upon the surface integrity (surface topography, dross, surface roughness, HAZ, recast layer, subsurface nanohardness, surface chemical composition). The univariate analysis was used to analyze and explain the influence that rules of process parameters had upon the surface integrity. The experiment results showed that the effects of process parameters on surface integrity were regular, with the optimal single-factor parameters obtained. Moreover, the removal mechanism of the nitinol material was also revealed. This study is of great significance for the medical industry in improve the cutting quality of cardiovascular stents.

Separating paint mist from paint spraying waste gas: mechanism, model and application

Yihui Zhou,Xi He,Wang Li,Tao Xu,Dong Xie,Xin Dai,Zhang Liu,Hanqing Wang,Gang Yu 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.5

The paint spraying waste gas contains a large amount of paint mist, volatile organic compounds (VOCs) and other hazardous materials, which seriously affects human health and atmospheric environment. Paint mist cannot be separated from paint spraying waste gas effectively by the existing dry filtration methods because of the filter blocking. A new separation process and a novel coupling device with high separation efficiency have been developed. A numerical model was established to optimize the structure and operation parameters of the baffle interceptor by hydrodynamics method which verified by the coupling device experiment. From the simulating results, when plate spacing was 20 ㎜, folding angle was 90° and airflow velocity was up to 8 ㎧, the separation efficiency of paint mist with the diameter of 15 ㎛ was 84.7% and the pressure drop of the baffle interceptor was 220.2 ㎩. Experiment was conducted under the above-optimized conditions, and the results showed that the pressure drop of the baffle interceptor was 303.33 ㎩, and the paint mist separation efficiencies of the baffle interceptor and the interception-filtration coupling device were 78.34% and 96.38%, respectively.

Differential Profile of Plasma Circular RNAs in Type 1 Diabetes Mellitus

Yangyang Li,Ying Zhou,Minghui Zhao,Jing Zou,Yuxiao Zhu,Xuewen Yuan,Qianqi Liu,Hanqing Cai,Cong-Qiu Chu,Yu Liu 대한당뇨병학회 2020 Diabetes and Metabolism Journal Vol.44 No.6

Background No currently available biomarkers or treatment regimens fully meet therapeutic needs of type 1 diabetes mellitus (T1DM). Circular RNA (circRNA) is a recently identified class of stable noncoding RNA that have been documented as potential biomarkers for various diseases. Our objective was to identify and analyze plasma circRNAs altered in T1DM. Methods We used microarray to screen differentially expressed plasma circRNAs in patients with new onset T1DM (n=3) and age-/gender-matched healthy controls (n=3). Then, we selected six candidates with highest fold-change and validated them by quantitative real-time polymerase chain reaction in independent human cohort samples (n=12). Bioinformatic tools were adopted to predict putative microRNAs (miRNAs) sponged by these validated circRNAs and their downstream messenger RNAs (mRNAs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to gain further insights into T1DM pathogenesis. Results We identified 68 differentially expressed circRNAs, with 61 and seven being up- and downregulated respectively. Four of the six selected candidates were successfully validated. Curations of their predicted interacting miRNAs revealed critical roles in inflammation and pathogenesis of autoimmune disorders. Functional relations were visualized by a circRNA-miRNA-mRNA network. GO and KEGG analyses identified multiple inflammation-related processes that could be potentially associated with T1DM pathogenesis, including cytokine-cytokine receptor interaction, inflammatory mediator regulation of transient receptor potential channels and leukocyte activation involved in immune response. Conclusion Our study report, for the first time, a profile of differentially expressed plasma circRNAs in new onset T1DM. Further in silico annotations and bioinformatics analyses supported future application of circRNAs as novel biomarkers of T1DM.