On 5-Axis Freeform Surface Machining Optimization: Vector Field Clustering Approach

My Chu A,Bohez Erik L J,Makhanov Stanlislav S,Munlin M,Phien Huynh N,Tabucanon Mario T Society for Computational Design and Engineering 2005 International Journal of CAD/CAM Vol.5 No.1

A new approach based on vector field clustering for tool path optimization of 5-axis CNC machining is presented in this paper. The strategy of the approach is to produce an efficient tool path with respect to the optimal cutting direction vector field. The optimal cutting direction maximizes the machining strip width. We use the normalized cut clustering technique to partition the vector field into clusters. The spiral and the zigzag patterns are then applied to generate tool path on the clusters. The iso-scallop method is used for calculating the tool path. Finally, our numerical examples and real cutting experiment show that the tool path generated by the proposed method is more efficient than the tool path generated by the traditional iso-parametric method.

Incidence and Risk Factors of Pneumonia in Hospitalized Patients with Seasonal Influenza A or B

Chu, Seongjun,Park, Sang Joon,Koo, So My,Kim, Yang Ki,Kim, Ki Up,Uh, Soo-Taek,Kim, Tae Hyung,Park, Suyeon The Korean Academy of Tuberculosis and Respiratory 2017 Tuberculosis and Respiratory Diseases Vol.80 No.4

Background: Most patients with influenza recover spontaneously or following treatment with an anti-viral agent, but some patients experience pneumonia requiring hospitalization. We conducted a retrospective review to determine the incidence and risk factors of pneumonia in hospitalized patients with influenza A or B. Methods: A total of 213 patients aged 18 years or older and hospitalized with influenza between January 2012 and January 2015 were included in this study. A reverse-transcriptase polymerase chain reaction assay was used to detect the influenza A or B virus in the patients' sputum samples. We collected demographic and laboratory data, combined coexisting diseases, and radiologic findings. Results: The incidence of pneumonia was higher in patients in the influenza A group compared to those in the influenza B group (68.6% vs. 56.9%), but this difference was not statistically significant. The presence of underlying respiratory disease was significantly associated with pneumonia in the influenza A group (adjusted odds ratio [OR], 3.975; 95% confidence interval [CI], 1.312-12.043; p=0.015). In the influenza B group, the white blood cell count (adjusted OR, 1.413; 95% CI, 1.053-1.896; p=0.021), platelet count (adjusted OR, 0.988; 95% CI, 0.978-0.999; p=0.027), and existence of an underlying medical disease (adjusted OR, 15.858; 95% CI, 1.757-143.088; p=0.014) were all significantly associated with pneumonia in multivariate analyses. Conclusion: The incidence of pneumonia was 65.7% in hospitalized patients with influenza A or B. The risk factors of pneumonia differed in hospitalized patients with influenza A or B.

Incidence and Risk Factors of Pneumonia in Hospitalized Patients with Seasonal Influenza A or B

( Seongjun Chu ),( Sang Joon Park ),( So My Koo ),( Yang Ki Kim ),( Ki Up Kim ),( Soo-taek Uh ),( Tae Hyung Kim ),( Suyeon Park ) 대한결핵 및 호흡기학회 2017 Tuberculosis and Respiratory Diseases Vol.80 No.4

Background: Most patients with influenza recover spontaneously or following treatment with an anti-viral agent, but some patients experience pneumonia requiring hospitalization. We conducted a retrospective review to determine the incidence and risk factors of pneumonia in hospitalized patients with influenza A or B. Methods: A total of 213 patients aged 18 years or older and hospitalized with influenza between January 2012 and January 2015 were included in this study. A reverse-transcriptase polymerase chain reaction assay was used to detect the influenza A or B virus in the patientsc sputum samples. We collected demographic and laboratory data, combined coexisting diseases, and radiologic findings. Results: The incidence of pneumonia was higher in patients in the influenza A group compared to those in the influenza B group (68.6% vs. 56.9%), but this difference was not statistically significant. The presence of underlying respiratory disease was significantly associated with pneumonia in the influenza A group (adjusted odds ratio [OR], 3.975; 95% confidence interval [CI], 1.312±12.043; p=0.015). In the influenza B group, the white blood cell count (adjusted OR, 1.413; 95% CI, 1.053±1.896; p=0.021), platelet count (adjusted OR, 0.988; 95% CI, 0.978±0.999; p=0.027), and existence of an underlying medical disease (adjusted OR, 15.858; 95% CI, 1.757±143.088; p=0.014) were all significantly associated with pneumonia in multivariate analyses. Conclusion: The incidence of pneumonia was 65.7% in hospitalized patients with influenza A or B. The risk factors of pneumonia differed in hospitalized patients with influenza A or B.

A novel mathematical modelling for simulating the spread of heavy metals in solid waste landfills

Ngoc Ha Hoang,Anh My Chu,Kim Thai Thi Nguyen,Chi Hieu Le 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.3

Municipal solid waste (MSW) landfills create the environmental pollutions due to problems related to toxins, leachate, and greenhouse gas, which are the growing environmental concerns, especially in developing countries. This paper presents a novel mathematical modelling for simulating the spread of heavy metals in soil layers in the MSW landfills. A new mathematical modelling procedure is studied for deriving the governing equation which describes the time varying concentration of pollutants in the leachate in a 3-dimensional (3D) space of soil layers. A Finite Element Method (FEM) based algorithm is then constructed to solve numerically the governing equation over time in 3D space for effectively analyzing the variation of pollutants concentrations. Finally, the applicability and advantages of the proposed novel method are demonstrated through the case study with soil samples collected from the actual MSW landfill. The successfully developed algorithm can be applied to model and predict the spread of different heavy metals in the MSW landfill sites; and to develop effective solutions and policies for solid waste classification and management, in order to minimise the negative impacts from the potential risk of the toxic heavy metal pollutions, soil contaminations and groundwater pollutions in the areas nearby the MSW landfill.

Association between High Diffusion-Weighted Imaging-Derived Functional Tumor Burden of Peritoneal Carcinomatosis and Overall Survival in Patients with Advanced Ovarian Carcinoma

An He,Perucho Jose AU,Chiu Keith WH,Hui Edward S,Chu Mandy MY,Ngu Siew Fei,Ngan Hextan YS,Lee Elaine YP 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.5

Objective: To investigate the association between functional tumor burden of peritoneal carcinomatosis (PC) derived from diffusion-weighted imaging (DWI) and overall survival in patients with advanced ovarian carcinoma (OC). Materials and Methods: This prospective study was approved by the local research ethics committee, and informed consent was obtained. Fifty patients (mean age ± standard deviation, 57 ± 12 years) with stage III–IV OC scheduled for primary or interval debulking surgery (IDS) were recruited between June 2016 and December 2021. DWI (b values: 0, 400, and 800 s/mm2) was acquired with a 16-channel phased-array torso coil. The functional PC burden on DWI was derived based on K-means clustering to discard fat, air, and normal tissue. A score similar to the surgical peritoneal cancer index was assigned to each abdominopelvic region, with additional scores assigned to the involvement of critical sites, denoted as the functional peritoneal cancer index (fPCI). The apparent diffusion coefficient (ADC) of the largest lesion was calculated. Patients were dichotomized by immediate surgical outcome into high- and low-risk groups (with and without residual disease, respectively) with subsequent survival analysis using the Kaplan-Meier curve and log-rank test. Multivariable Cox proportional hazards regression was used to evaluate the association between DWI-derived results and overall survival. Results: Fifteen (30.0%) patients underwent primary debulking surgery, and 35 (70.0%) patients received neoadjuvant chemotherapy followed by IDS. Complete tumor debulking was achieved in 32 patients. Patients with residual disease after debulking surgery had reduced overall survival (p = 0.043). The fPCI/ADC was negatively associated with overall survival when accounted for clinicopathological information with a hazard ratio of 1.254 for high fPCI/ADC (95% confidence interval, 1.007–1.560; p = 0.043). Conclusion: A high DWI-derived functional tumor burden was associated with decreased overall survival in patients with advanced OC.