An Enhanced Password Authentication Scheme Providing Password Updating without Smart Cards

Chin-Chen Chang,Hao-Chuan Tsai,Yi-Hui Chen 보안공학연구지원센터 2007 International Journal of Security and Its Applicat Vol.1 No.2

In 2003, Yang, Chang, and Hwang proposed an enhanced scheme of Peyravivan-Zunic’s password authentication scheme by using the Diffie-Hellman scheme. Later, Yoon, Ryu, and Yoo demonstrated that Yang-Chang-Hwang’s scheme is vulnerable to a stolen-verifier attack and a denial-of-service attack, and then proposed an improved scheme. In this paper, we show that Yoon-Ryu-Yoo’s scheme is still vulnerable to a stolen-verifier attack and a server spoofing attack under some reasonable assumption. In addition, we propose an improved scheme to eliminate such security flaws.

The Effect of Beta-Herding on Taiwan’s Market: DCC-MIDAS Approach

Yi Chang Chen Cong Huang,Chunxiu Qiu,Yantong Jin,Xinyi Ma 한국유통과학회 2017 KODISA ICBE (International Conference on Business Vol.2017 No.-

The aim of this study is to investigate the herding of beta transmission between return and volatility. We have used the dynamic conditional correlation model with the mixed-data sampling (DCC-MIDAS) model for the analysis. Evidence demonstrates that herding is a key transmitter in Taiwan’s stock market. The significant estimation of DCC-MIDAS explains the herding phenomenon is highly dynamic and time-varying in herding behavior. By means of time-varying beta of herding based on our rolling forecasting method and robustness check of the Markov switching regression approach using four types of portfolios, we find evidence of superior forecasting ability of the model indicates that there are conditional correlations between betas and herding. The evidence also reveals herding formation in Taiwan’s markets during the subprime crisis period.

Using Team resource management to improve the execution rate of cardiac rehabilitation exercise

Chen Mei-Jia,Chen Mei-Jia,Yu Chen-Yi,Chou Yi-Ling,Lin Hsin-Yi,Chang Hui-Mei 한국간호과학회 2023 한국간호과학회 학술대회 Vol.2023 No.11

Effect of the Circle-Grid Electrodes on Concentrated GaAs Solar Cell Efficiency

Chen-Chen Chung,Binh Tinh Tran,Ming-Hung Han,Kung-Liang Lin,Hung-Wei Yu,Yen-Teng Ho,Chun-Yen Chang,Edward Yi Chang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.5

In this study, we investigate the effect of the shading factor of the front grid pattern on concentrated solar cell efficiency, taking the trade-off between the series resistance of the electrodes and the amount of incident light into consideration. We examine the thermal effect with regard to five different circle-grid electrode patterns of the front contact. The front contacts with different grid patterns affect the characteristics of light-concentratedtype GaAs single-junction solar cells. The device parameters analyzed include the open-circuit voltage (Voc), short-circuit current (Isc), fill factor (FF) and conversion efficiency (η). The results of our study show that for a concentration ratio greater than 60x with AM1.5G, the device with a shading factor of 7.1% has the best cell efficiency of 27.05%, due to the smaller current crowding at the center spot. The results indicate that the conversion efficiency of solar cells can be improved by establishing a compromise between the shading effect and the series resistance effect.

An Inverted U-shaped Relationship between Information Transparency and Idiosyncratic Risk

Yi Chang Chen,Mao Feng Kao,Hui Cheng Yu,Yuwen Yang,Yixuan Fu 한국유통과학회 2017 KODISA ICBE (International Conference on Business Vol.2017 No.-

Prior literature indicates that the endogeneity problem exists between information transparency and idiosyncratic risk, and that the results of the impact of transparency on risk are still inconclusive. This study attempts to employ a simultaneous equation model to investigate the non-linear relationship between information transparency and idiosyncratic risk. The variables of firm’s information transparency are drawn from the “Annual Report on China’s Companies’ Public Transparency” published by the China Social Science Academic Press. The finding indicates that an inverted U-shaped relationship exists between information transparency and idiosyncratic risk. The empirical result of the non-linear relation not only confirms the disclosure theory that the relationship between information transparency and idiosyncratic risk is negative, but also explains the inconsistent evidence in previous research.

The Effect of CdS QDs Structure on the InGaP/GaAs/Ge Triple Junction Solar Cell Efficiency

Chen-Chen Chung,Binh Tinh Tran,Hau-Vei Han,Yen-Teng Ho,Hung-Wei Yu,Kung-Liang Lin,Hong-Quan Nguyen,Peichen Yu,Hao-Chung Kuo,Edward Yi Chang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2

This work describes optical and electrical characteristics of InGaP/GaAs/Ge triple-junction (T-J) solar cells with CdS quantum dots (QDs) fabricated by a novel chemical solution. With the anti-reflective feature at long wavelength and down-conversion at UV regime, the CdS quantum dot effectively enhance the overall power conversion efficiency more than that of a traditional GaAs-based device. Experimental results indicate that CdS quantum dot can enhance the short-circuit current by 0.33 mA/cm2, which is observed for the triple-junction solar cells with CdS QDs of about 3.5 nm in diameter. Moreover, the solar cell conversion efficiency is improved from 28.3% to 29.0% under one-sun AM 1.5 global illumination I-V measurement.

An update of preimplantation genetic diagnosis in gene diseases, chromosomal translocation, and aneuploidy screening

Chang, Li-Jung,Chen, Shee-Uan,Tsai, Yi-Yi,Hung, Chia-Cheng,Fang, Mei-Ya,Su, Yi-Ning,Yang, Yu-Shih The Korean Society for Reproductive Medicine 2011 Clinical and Experimental Reproductive Medicine Vol.38 No.3

Preimplantation genetic diagnosis (PGD) is gradually widely used in prevention of gene diseases and chromosomal abnormalities. Much improvement has been achieved in biopsy technique and molecular diagnosis. Blastocyst biopsy can increase diagnostic accuracy and reduce allele dropout. It is cost-effective and currently plays an important role. Whole genome amplification permits subsequent individual detection of multiple gene loci and screening all 23 pairs of chromosomes. For PGD of chromosomal translocation, fluorescence $in-situ$ hybridization (FISH) is traditionally used, but with technical difficulty. Array comparative genomic hybridization (CGH) can detect translocation and 23 pairs of chromosomes that may replace FISH. Single nucleotide polymorphisms array with haplotyping can further distinguish between normal chromosomes and balanced translocation. PGD may shorten time to conceive and reduce miscarriage for patients with chromosomal translocation. PGD has a potential value for mitochondrial diseases. Preimplantation genetic haplotyping has been applied for unknown mutation sites of single gene disease. Preimplantation genetic screening (PGS) using limited FISH probes in the cleavage-stage embryo did not increase live birth rates for patients with advanced maternal age, unexplained recurrent abortions, and repeated implantation failure. Polar body and blastocyst biopsy may circumvent the problem of mosaicism. PGS using blastocyst biopsy and array CGH is encouraging and merit further studies. Cryopreservation of biopsied blastocysts instead of fresh transfer permits sufficient time for transportation and genetic analysis. Cryopreservation of embryos may avoid ovarian hyperstimulation syndrome and possible suboptimal endometrium.

Investment and Determinants of Investment Cash Flow Sensitivity : Evidence from Privately Listed Chinese Firms

Yi Chang Chen,Huo Lien Tsai,Yanzhang Qiu,Linna Deng,Lin Yu 한국유통과학회 2017 KODISA ICBE (International Conference on Business Vol.2017 No.-

This study examines firm-level capital investment efficiency and the determinants of investment cash flow sensitivity (CFS). Using financial and ultimate ownership structure data from China, we show that privately listed Chinese firms with high accounting quality tend to increase investment expenditures and have underinvestment problems. Previous studies have claimed that a positive relation exists between investment and cash flow in China, but our results do not support high investment-CFS caused by agency costs. By contrast, our results suggest that firms with high investment-CFS may be highly constrained financially. We also find that a negative relation exists between investment opportunity and investment-CFS. In addition, younger firms face higher investment-CFS.

Breast density analysis for whole breast ultrasound images : Whole breast ultrasound density analysis

Chen, Jeon-Hor,Huang, Chiun-Sheng,Chien, Kuang-Che Chang,Takada, Etsuo,Moon, Woo Kyung,Wu, Jeffery H. K.,Cho, Nariya,Wang, Yi-Fa,Chang, Ruey-Feng Wiley (John WileySons) 2009 Medical physics Vol.36 No.11

<P>Breast density has been established as an independent risk factor associated with the development of breast cancer. The terms mammographic density and breast density are often used interchangeably, since most breast density studies are performed with projection mammography. It is known that increase in mammographic density is associated with an increased cancer risk. A sensitive method that allows for the measurement of small changes in breast density may provide useful information for risk management. Despite the efforts to develop quantitative breast density measurements from projection mammograms, the measurements show large variability as a result of projection imaging, differing body position, differing levels of compression, and variation of the x-ray beam characteristics. This study used two separate computer-aided methods, threshold-based and proportion-based evaluations, to analyze breast density on whole breast ultrasound (US) imaging and to compare with the grading results of three radiologists using projection mammography. Thirty-two female subjects with 252 images per case were included in this study. Whole breast US images were obtained from an Aloka SSD-5500 ultrasound machine with an ASU-1004 transducer (Aloka, Japan). Before analyzing breast density, an adaptive speckle reduction filter was used for removing speckle noise, and a robust thresholding algorithm was used to divide breast tissue into fatty or fibroglandular classifications. Then, the proposed approaches were applied for analysis. In the threshold-based method, a statistical model was employed to determine whether each pixel in the breast region belonged to fibroglandular or fatty tissue. The proportion-based method was based on three-dimensional information to calculate the volumetric proportion of fibroglandular tissue to the total breast tissue. The experimental cases were graded by the proposed analysis methods and compared with the ground standard density classification assigned by a majority voting of three experienced breast radiologists. For the threshold-based method, 28 of 32 US test cases and for the proportion-based density classifier, 27 of 32 US test cases were found to be in agreement with the radiologist 'ground standard' mammographic interpretations, resulting in overall accuracies of 87.5% and 84.4%, respectively. Moreover, the concordance values of the proposed methods were between 0.0938 and 0.1563, which were less than the average interobserver concordance of 0.3958. The experiment result showed that the proposed methods could be a reference opinion and offer concordant and reliable quantification of breast density for the radiologist.</P>

Dual-Active-Bridge Converter with Triple Phase Shift Control for a Wide Operating Voltage Range

Yi-Hsuan Chen,Ta-Wei Huang,Shih-Hao Kuo,Yu-Chen Chang,Huang-Jen Chiu,Serafin Bachman,Marek Jasi?ski 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

An optimal modulation scheme with Triple-Phase-Shift (TPS) control that increase efficiency in the whole load range is presented for a Dual Active Bridge (DAB) converter under wide output voltage range conditions. This paper provides a comprehensive analysis of the DAB with TPS modulation, identifying all the switching modes to operate the DAB where expressions for the transfer functions, the peak inductor current and RMS inductor current are provided. An analysis of minimum Peak Current and minimum RMS Current Control also are investigated. On this basic all-ZVS modulation scheme is originally proposed to improve light-load efficiency and to reduce the switching losses. A 15 kW prototype circuit is applied, and experimental results are presented to validate that the modulation and efficiency improvement are realized by applying the optimized modulation scheme. The experimental results also verify the effectiveness of the closed-loop control strategy.