Evaluation of a New Workplace Protection Factor―Measuring Method for Filtering Facepiece Respirator

Sun, Chenchen,Thelen, Christoph,Sanz, Iris Sancho,Wittmann, Andreas Occupational Safety and Health Research Institute 2020 Safety and health at work Vol.11 No.1

Background: This study aims to assess whether the TSI PortaCount (Model 8020) is a measuring instrument comparable with the flame photometer. This would provide an indication for the suitability of the PortaCount for determining the workplace protection factor for particulate filtering facepiece respirators. Methods: The PortaCount (with and without the N95-Companion^TM) was compared with a stationary flame photometer from Moores (Wallisdown) Ltd (Type 1100), which is a measuring instrument used in the procedure for determining the total inward leakage of the particulate filtering facepiece respirator in the European Standard. Penetration levels of sodium chloride aerosol through sample respirators of two brands (A and B) were determined by the two measuring systems under laboratory conditions. For each brand, thirty-six measurements were conducted. The samples were split into groups according to their protection level, conditioning before testing, and aerosol concentration. The relationship between the gauged data from two measuring systems was determined. In addition, the particle size distribution inside the respirator and outside the respirator was documented. Linear regression analysis was used to calculate the association between the PortaCount (with and without the N95-Companion^TM) and the flame photometer. Results: A linear relationship was found between the raw data scaled with the PortaCount (without N95-Companion^TM) and the data detected by the flame photometer (R² = 0.9704) under all test conditions. The distribution of particle size was found to be the same inside and outside the respirator in almost all cases. Conclusion: Based on the obtained data, the PortaCount may be applicable for the determination of workplace protection factor.

No-reference Image Blur Assessment Based on Multi-scale Spatial Local Features

( Chenchen Sun ),( Ziguan Cui ),( Zongliang Gan ),( Feng Liu ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.10

Blur is an important type of image distortion. How to evaluate the quality of blurred image accurately and efficiently is a research hotspot in the field of image processing in recent years. Inspired by the multi-scale perceptual characteristics of the human visual system (HVS), this paper presents a no-reference image blur/sharpness assessment method based on multi-scale local features in the spatial domain. First, considering various content has different sensitivity to blur distortion, the image is divided into smooth, edge, and texture regions in blocks. Then, the Gaussian scale space of the image is constructed, and the categorized contrast features between the original image and the Gaussian scale space images are calculated to express the blur degree of different image contents. To simulate the impact of viewing distance on blur distortion, the distribution characteristics of local maximum gradient of multi-resolution images were also calculated in the spatial domain. Finally, the image blur assessment model is obtained by fusing all features and learning the mapping from features to quality scores by support vector regression (SVR). Performance of the proposed method is evaluated on four synthetically blurred databases and one real blurred database. The experimental results demonstrate that our method can produce quality scores more consistent with subjective evaluations than other methods, especially for real burred images.

Robust Finite Time Tracking Control for Robotic Manipulators Based on Nonsingular Fast Terminal Sliding Mode

Chenchen Sun 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.10

In this paper, a novel disturbance observer-based robust nonsingular fast terminal sliding mode control (RNFTSMC) technique is proposed for tracking control of robotic manipulators with time-varying disturbances. First, an improved form of nonsingular fast terminal sliding manifold is developed to achieve the strong robustness and finite time convergence of the system, and to avoid the singularity problem. Second, a continuous robust reaching law is designed not only to attenuate chattering phenomena without deteriorating the system tracking precision, but also to guarantee the finite time stability of the system. Furthermore, a nonlinear disturbance observer (NDOB) is employed to estimate the system uncertainties and decrease the switching gain, so that the prior information about the perturbations is not required, and the control signal can be reduced with fewer chattering effect. The system stability is analyzed according to the Lyapunov stability theory. Finally, the superiority of the proposed control scheme is validated by comparative simulation studies.

Sliding Mode Control with Adaptive Fuzzy Immune Feedback Reaching Law

Chenchen Sun,Guo-fang Gong,Hua-yong Yang 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.2

In this paper, a novel adaptive fuzzy immune feedback reaching law (AFIFRL) based sliding mode control (SMC) strategy is proposed for uncertain nonlinear systems with time-varying disturbances. First, a nonlinear immune feedback reaching law (IFRL) inspired by biological immune feedback regulation mechanism is designed to alleviate chattering effect without losing the robustness against disturbances. Second, an improved IFRL is developed in a thin boundary layer to enhance tracking performance. Then, the applied fuzzy controller adjusts the boundary layer online to further improve control performance despite large system uncertainties and disturbances. Furthermore, an adaptive law is employed to estimate the unknown bound of uncertainties, which can effectively attenuate chattering and minimize control effort. The stability analysis is derived by Lyapunov stability theorem. Finally, numerical simulations are conducted to evidence the effectiveness and superiority of the proposed AFIFRL based SMC scheme.

영어의 반사실적 조건문을 위한 교수 전략

첸첸 쑨(Chenchen Sun),임어경(번역자) 부산대학교 인문학연구소 2007 코기토 Vol.- No.61

To facilitate ESL learners acquire and understand how to manipulate the backshifting system and modal auxiliary in English counterfactual conditionals, this study first addresses the syntactic structure of counterfactual conditionals including their forms, meaning, and use. Second, it proposes an effective teaching strategy that combines Structural syntactic theory and grammar teaching theory with the two communicative approach teaching methods (Cooperative Language Learning and Content-based Instruction). Since the syntactic structure and the interpretation of the verb wish are identical to the if clause of counterfactual conditionals, they are well suited for serving as the first step in acquiring the backshifting verb forms used in counterfactual conditionals. Prior to introducing the multifaceted counterfactual conditionals, teaching the structure of wish sentences and illustrating the counterfactuality through wish constructions will definitely help ESL learners acquire and construct English counterfactual conditionals with greater accuracy and speed.

[기획논문] 영어의 반사실적 조건문을 위한 교수 전략

첸첸 쑨 부산대학교 인문학연구소 2007 코기토 Vol.- No.61

To facilitate ESL learners acquire and understand how to manipulate the backshifting system and modal auxiliary in English counterfactual conditionals,this study first addresses the syntactic structure of counterfactual conditionals including their forms, meaning, and use. Second, it proposes an effective teaching strategy that combines structural syntactic theory and grammar teaching theory with the two communicative approach teaching methods (Cooperative Language Learning and Content-based Instruction). Since the syntactic structure and the interpretation of the verb wish are identical to the if clause of counterfactual conditionals, they are well suited for serving as the first step in acquiring the backshifting verb forms used in counterfactual conditionals. Prior to introducing the multifaceted counterfactual conditionals, teaching the structure of wish sentences and illustrating the counterfactuality through wish constructions will definitely help ESL learners acquire and construct English counterfactual conditionals with greater accuracy and speed.

Factors Influencing Corporate Social Responsibility Accounting Information Disclosure - Based on China's Petroleum Industry -

Fanghua Sun,KyongGu Rhee,Chenchen Chen 동중앙아시아경상학회 2019 한몽경상연구 Vol.30 No.2

With the wave of economic globalization, China has witnessed rapid development of economy, whereas some enterprises caused many social problems in the pursuit of profit. Therefore, it has become the general expectation and requirement of modern society for enterprises to shoulder corporate social responsibility (CSR), and disclose CSR accounting information to reflect their performance; the issue of how enterprises fulfill CSR has become a widely concerned topic of Chinese government, non-profit organizations and the public. This paper first review the literature, then demonstrates a research model to explore the factors influencing the CSR accounting information disclosure, focusing data from listed companies in petroleum industry. The study finds out that institutional investors shareholding ratio, accounts payable ratio and media exposure have significant positive impact on CSR accounting information disclosure, and puts forward related measures to improve the CSR accounting information disclosure.

Adaptive Global Robust Tracking Control for Uncertain Dynamic Systems

Zhangmin Huang,Chenchen Sun 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.4

In order to achieve excellent tracking performance of dynamic systems under uncertain disturbances, this paper devises an adaptive dynamic global robust sliding mode control (ADGRSMC) approach. An innovative global robust sliding manifold is designed by integrating an auxiliary function into a proportional-integral-derivative (PID) type sliding structure, which can not only omit the reaching stage and achieve global robustness, but also perform fast transient response and suppress steady state errors. Then, a dynamic nonsingular terminal sliding structure is conceived to attenuate chattering phenomena without deteriorating the tracking accuracy and robustness property. Furthermore, a novel adaptive law has been developed to adjust the switching gain, so that the prior information of perturbations is unnecessary and the chattering effect can be further alleviated. The finite time stability of the adopted ADGRSMC approach has been proven according to the Lyapunov stability theory, and its superiority is validated through comparative simulation studies.

상형자 학습에 미치는 그림의 효과연구

金善娥(Kim, Sun-a),申修瑛(Shin, Soo-young),毛晨晨(Mao Chenchen),辛承姬(Shin, Seung-hee) 중국어문학연구회 2016 중국어문학논집 Vol.0 No.99

It has been reported that there are phases in children’s reading development, and that children depend on salient visual features in or around target words to read in the first phase. The current study investigated whether pictures as visual stimuli help learning pictographic characters by young beginning readers of Chinese who are supposed to be in the first reading stage. A total of 40 children at an age of five on average participated in an experiment of learning pictographs and a Chinese character test, which were conducted in a city of Southern China. Fifteen participants were native (L1) Chinese who read Pinyin but recognized a limited number of characters. The other 25 children were non-native learners of Chinese as a second language (L2), who had learned spoken Chinese for less than two months almost without any knowledge of Chinese characters. Participating children learned 12 pictographs, six of which were presented with pictures (i.e., picture condition) and the other six without pictures (i.e., no-picture condition) in three trials. The results showed that both L1 and L2 learners found the advantages of pictures in learning the meanings and the pronunciations of the pictographs, but the pictures were more beneficial to learning the pronunciations than the meanings. The findings verify the effects of pictures in learning pictographs, especially for their pronunciation. In addition, L1 Chinese children displayed more balanced outcomes in learning meanings and pronunciations. On the contrary, L2 learners indicated higher performance in learning meaning than in pronunciation regardless of the pictures, which suggests that the pronunciations of pictographs need to be emphasized more, and thus, pictures should be utilized more in teaching novice L2 learners pictographic characters.

Accurate transfer of bimaxillary orthognathic surgical plans using computer-aided intraoperative navigation

Chen Chen,Ningning Sun,Chunmiao Jiang,Yanshan Liu,Jian Sun 대한치과교정학회 2021 대한치과교정학회지 Vol.51 No.5

Objective: To examine the accuracy of computer-aided intraoperative navigation (Ci-Navi) in bimaxillary orthognathic surgery by comparing preoperative planning and postoperative outcome. Methods: The study comprised 45 patients with congenital dentomaxillofacial deformities who were scheduled to undergo bimaxillary orthognathic surgery. Virtual bimaxillary orthognathic surgery was simulated using Mimics software. Intraoperatively, a Le Fort I osteotomy of the maxilla was performed using osteotomy guide plates. After the Le Fort I osteotomy and bilateral sagittal split ramus osteotomy of the mandible, the mobilized maxilla and the distal mandibular segment were fixed using an occlusal splint, forming the maxillomandibular complex (MMC). Realtime Ci-Navi was used to lead the MMC in the designated direction. Osteoplasty of the inferior border of the mandible was performed using Ci-Navi when facial symmetry and skeletal harmony were of concern. Linear and angular distinctions between preoperative planning and postoperative outcomes were calculated. Results: The mean linear difference was 0.79 mm (maxilla: 0.62 mm, mandible: 0.88 mm) and the overall mean angular difference was 1.20°. The observed difference in the upper incisor point to the Frankfort horizontal plane, midfacial sagittal plane, and coronal plane was < 1 mm in 40 cases. Conclusions: This study demonstrates the role of Ci-Navi in the accurate positioning of bone segments during bimaxillary orthognathic surgery. Ci-Navi was found to be a reliable method for the accurate transfer of the surgical plan during an operation.