Effects of Neodymium and Calcium on the Thermal Stability of AZ71 Magnesium Alloys

Cheng‑Feng Yue,Shi‑Jei Huang,Jhewn‑Kuang Chen,Hsien‑Tsung Li,Kam‑Shau Chan 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.2

The effects of an addition of 0–2 wt% Nd on thermal stability of 0–3 wt% Ca-containing modified AZ71 magnesium alloyswas investigated. The ignition temperature was found to increase from that of AZ71, 574, to 825 °C with the addition of0.5 wt% Ca and 1 wt% Nd. The ignition temperature was further increased to 1114 °C when 3 wt% Ca was added. The CaandNd-added AZ71 was isothermally maintained at a temperature of 500 °C in air for 12 h. The MgO–CaO–Nd2O3 formedon the surface to improve the thermal stability of the AZ71–xCa–yNd alloys. While both the tensile strength and ductilitydecreased with the Ca concentration in the alloy, an addition of 1 wt% Nd was found able to alleviate the degradation effectsof Ca on the tensile strength and ductility at 170 °C. Both solid solution formation and precipitation strengthening contributedto the increase in toughness. AZ71 containing 0.5–2 wt% Ca and 1 wt% Nd provides the optimum combination of ignitionresistance and mechanical properties.

The feasibility of detecting endometrial and ovarian cancer using DNA methylation biomarkers in cervical scrapings

Cheng-Chang Chang,Hui-Chen Wang,Yu-Ping Liao,Yu-Chih Chen,Yu-Chun Weng,Mu-Hsien Yu,Hung-Cheng Lai 대한부인종양학회 2018 Journal of Gynecologic Oncology Vol.29 No.1

Objective: We hypothesized that DNA methylation of development-related genes may occur in endometrial cancer (EC)/ovarian cancer (OC) and may be detected in cervical scrapings. Methods: We tested methylation status by quantitative methylation-specific polymerase chain reaction for 14 genes in DNA pools of endometrial and OC tissues. Tissues of EC/normal endometrium, OC/normal ovary, were verified in training set using cervical scrapings of 10 EC/10 OC patients and 10 controls, and further validated in the testing set using independent cervical scrapings in 30 EC/30 OC patients and 30 controls. We generated cutoff values of methylation index (M-index) from cervical scrapings to distinguish between cancer patients and control. Sensitivity/specificity of DNA methylation biomarkers in detecting EC and OC was calculated. Results: Of 14 genes, 4 (PTGDR, HS3ST2, POU4F3, MAGI2) showed hypermethylation in EC and OC tissues, and were verified in training set. POU4F3 and MAGI2 exhibited hypermethylation in training set were validated in independent cases. The mean M-index of POU4F3 is 78.28 in EC and 20.36 in OC, which are higher than that in controls (6.59; p<0.001 and p=0.100, respectively), and that of MAGI2 is 246.0 in EC and 12.2 in OC, which is significantly higher that than in controls (2.85; p<0.001 and p=0.480, respectively). Sensitivity and specificity of POU4F3/MAGI2 were 83%–90% and 69%–75% for detection of EC, and 61% and 62%–69% for the detection of OC. Conclusion: The findings demonstrate the potential of EC/OC detection through testing for DNA methylation in cervical scrapings.

Carbon black sintering effects on the composition of multiphase calcium phosphate bioceramics

Wen-Cheng Chen,Chien-Ping Ju,Wen-Hsien Cheng,Jiin-Huey Chern Lin 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.3

The presence of carbonate (CO3 2-) combined with calcium phosphates has been believed to increase the susceptibility of natural bone formation. This study was carried out to investigate the thermal properties of apatite in nano scale precipitates with added carbon black that could act as a sintering inhibitor and a carbonate preserver. In addition, the present study aimed to determine the effects of those additives and analyze their chemical compositions. Ceramics processed at different heating temperatures were compared and characterized. The results showed that a multiphase ceramic of apatite-calcium carbonate (CaCO3)-calcium oxide (CaO) was formed in a temperature range of 600 to 800 ο C. By observing the morphologies of the ceramics, the addition of carbon black which acts as a carbonate supplier in the heating processes and further as an inhibitor to prevent the sintering effect of the nano scale particles in sub-micro range efficiently at 1400 ο C were established.

Resonant-Frequency-Dependent Flux Noise of a High-TC rf SQUID Coupled to a Substrate Resonator

Ji-Cheng Chen,Hong-Chang Yang,Chiu-Hsien Wu,Herng-Er Horng,Jen-Tzong Jeng,Kuen-Lin Chen 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.5I

In the recent development of a high-TC rf SQUID magnetometer, Zhang et al. used a SrTiO3 substrate resonator with a YBCO thin film flux concentrator on it. The effective area was improved by a flux concentrator. However, there was no study of the resonant frequency of the substrate resonator. In this work, the frequency-dependent flux noise of a high-TC rf SQUID coupled to a substrate resonator was investigated. The results were analyzed with the noise theory. The optimization of the SQUID with a substrate resonator and its flux noise are discussed.

The back contact modification in high-efficiency Cu₂ZnSn(S,Se)₄ solar cells by a thin MoO₃ layer

Septia KHOLIMATUSSADIAH,Cheng-Ying CHEN,Wei-Chao CHEN,Yi-Rung LIN,Shao-Hung LU,Meng-Chia HSIEH,Jan-Kai CHANG,Chih-I WU,Ruei-San CHEN,Kuei-Hsien CHEN,Li-Chyong CHEN 한국진공학회 2016 한국진공학회 학술발표회초록집 Vol.2016 No.8

Value of CT in the Discrimination of Fatal from Non-Fatal Stercoral Colitis

Cheng-Hsien Wu,Chen-Chih Huang,Li-Jen Wang,Yon-Cheong Wong,Chao-Jan Wang,Wan-Chak Lo,Being-Chuan Lin,Yung-Liang Wan,Chuen Hsueh 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.3

Objective: Clinical presentation and physical signs may be unreliable in the diagnosis of stercoral colitis (SC). This study evaluates the value of computed tomography (CT) in distinguishing fatal from non-fatal SC. Materials and Methods: Ten patients diagnosed as SC were obtained from inter-specialist conferences. Additional 13 patients with suspected SC were identified via the Radiology Information System (RIS). These patients were divided into two groups; fatal and non-fatal SCs. Their CT images are reviewed by two board-certified radiologists blinded to the clinical data and radiographic reports. Results: SC occurred in older patients and displayed no gender predisposition. There was significant correlation between fatal SC and CT findings of dense mucosa (p = 0.017), perfusion defects (p = 0.026), ascites (p = 0.023), or abnormal gas (p = 0.033). The sensitivity, specificity, and accuracy of dense mucosa were 71%, 86%, and 81%, respectively. These figures were 75%, 79%, and 77% for perfusion defects; 75%, 80%, and 78% for ascites; and 50%, 93%, and 78% for abnormal gas, respectively. Each CT sign of mucosal sloughing and pericolonic abscess displayed high specificity of 100% and 93% for diagnosing fatal SC, respectively. However, this did not reach statistical significance in diagnosing fatal SC. Conclusion: CT appears to be valuable in discriminating fatal from non-fatal SC. Objective: Clinical presentation and physical signs may be unreliable in the diagnosis of stercoral colitis (SC). This study evaluates the value of computed tomography (CT) in distinguishing fatal from non-fatal SC. Materials and Methods: Ten patients diagnosed as SC were obtained from inter-specialist conferences. Additional 13 patients with suspected SC were identified via the Radiology Information System (RIS). These patients were divided into two groups; fatal and non-fatal SCs. Their CT images are reviewed by two board-certified radiologists blinded to the clinical data and radiographic reports. Results: SC occurred in older patients and displayed no gender predisposition. There was significant correlation between fatal SC and CT findings of dense mucosa (p = 0.017), perfusion defects (p = 0.026), ascites (p = 0.023), or abnormal gas (p = 0.033). The sensitivity, specificity, and accuracy of dense mucosa were 71%, 86%, and 81%, respectively. These figures were 75%, 79%, and 77% for perfusion defects; 75%, 80%, and 78% for ascites; and 50%, 93%, and 78% for abnormal gas, respectively. Each CT sign of mucosal sloughing and pericolonic abscess displayed high specificity of 100% and 93% for diagnosing fatal SC, respectively. However, this did not reach statistical significance in diagnosing fatal SC. Conclusion: CT appears to be valuable in discriminating fatal from non-fatal SC.

Investigation of Visual Perception Under Zen-Meditation Based On Alpha-Dependent F-VEPs

Liao, Hsien-Cheng,Liu, Chuan-Yi,Lo, Pei-Chen The Korean Society of Medical and Biological Engin 2006 의공학회지 Vol.27 No.6

Variation of brain dynamics under Zen meditation has been one of our major research interests for years. One issue encountered is the inaccessibility to the actual meditation level or stage as a reference. In this paper, we propose an alternative strategy for investigating the human brain in response to external flash stimuli during Zen meditation course. To secure a consistent condition of the brain dynamics when applying stimulation, we designed a recording of flash visual evoked potentials (F-VEPs) based on a constant background EEG (electroencephalograph) frontal $\alpha-rhythm$ dominating activities that increase significantly during Zen meditation. Thus the flash-light stimulus was to be applied upon emergence of the frontal $\alpha-rhythm$. The alpha-dependent F-VEPs were then employed to inspect the effect of Zen meditation on brain dynamics. Based on the experimental protocol proposed, considerable differences between experimental and control groups were obtained. Our results showed that amplitudes of P1-N2 and N2-P2 on Cz and Fz increased significantly during meditation, contrary to the F-VEPs of control group at rest. We thus suggest that Zen meditation results in acute response on primary visual cortex and the associated parts.

The Study of the Cycle Time Improvement by Work-In-Process Statistical Process Control Method for IC Foundry Manufacturing

Yu Cheng Lin,Chih Hung Tsai,Rong Kwei Li,Ching Piao Chen,Hsien Ching Chen 한국품질경영학회 2008 The Asian Journal on Quality Vol.9 No.3

The definition of cycle time is the time from the wafer start to the wafer output. It usually takes one or two months to get the product since customer decides to produce it. The cycle time is a critical factor for customer satisfaction because it represents the response time to the market. Long cycle time reflects the ineffective investment for the capital. The cycle time is very important for foundry because long cycle time will cause customer unsatisfied and the order loss. Consequently, all of the foundries put lots of human source in the cycle time improvement. Usually, we make decisions based on the experience in the cycle time management. We have no mechanism or theory for cycle time management. We do work-in-process (WIP) management based on turn rate and standard WIP (STD WIP) set by experiences. But the experience didn`t mean the optimal solution, when the situation changed, the cycle time or the standard WIP will also be changed. The experience will not always be applicable. If we only have the experience and no mechanism, management will not be work out. After interview several foundry fab managers, all of the fab can`t reflect the situation. That is, all of them will have an impact period after product mix or utilization varied. In this study, we want to develop a formula for standard WIP and use statistical process control (SPC) concept to set WIP upper/lower limit level. When WIP exceed the limit level, it will trigger action plans to compensate WIP Profile. If WIP Profile balances, we don`t need too much WIP. So WIP level could be reduced and cycle time also could be reduced.

Atomistic Simulation of ZrNi Metallic Glasses Under Torsion Test

Po-Hsien Sung,Tei-Chen Chen,Cheng-Da Wu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.8

ZrNi metallic glass alloy nanowires (NWs) under torsion are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The effect of cooling rate on the deformation mechanism and mechanical properties of ZrNi NWs is evaluated in terms of shear strain, torque, potential energy and radial distribution function. Simulation results show that for slower cooling rates, the NWs have larger packing density, whereas for faster cooling rates, the packing density of atoms decreases. The amount of deformation increases with increasing torsional angle before it reaches a critical torsional angle (θc). The torque required for deformation and the θc value increase with decreasing cooling rate, indicating a larger mechanical strength. Localized shear bands concentrate at regions with high shear strains, leading to the formation of torsional buckling.

FEM ANALYSIS AND EXPERIMENT VALIDATION ON MULTI-PASS FORGING OF TORX ROUND FLANGE BOLT

Shih-Hsien Lin,Dyi-Cheng Chen,Un-Chin Chai,Gow-Yi Tzou 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.5

This study aims at exploring the multi-pass forging of Torx Round Flange Bolt (automotive fastener) to simulate each pass forging process using FEM simulation. The software is used to carry out the simulation analysis. Constant shear friction is always assumed at the interface between die and workpiece to explore the effective stress, the effective strain, the velocity filed, and the forging force for each pass. Through the pass schedule plan and design based on FEM analysis, the four-pass forging process is designed to form the Torx Round Flange Bolt compared the five-pass forging. It is noted that the total forging force is 1204kN, so the 200 tons machinery in the factory can be chosen to manufacture this automotive fastener. The die stress analysis for each pass has been explored to realize whether the dies are damaged or not. The forming feasibility of Torx Round Flange Bolt can be performed by FEM simulation. All dies designs and forming results can be proposed to the dies manufacture so as to perform the realistic experiments. Comparisons between FEM and experiment for final product dimensions can be carried out. The maximum dimension error is just around 3.32% to show a good agreement with the experiment. The research results can provide to the industries as the references of establishment of multi-pass forging technology.