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      • Design of Current Sensorless Control for Totem-Pole Boost PFC Converter

        Che-Yu Lu,Yi-Wen Hsu,Hung-Chi Chen 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

        A simple current sensorless control for totem-pole boost converter is aimed to achieve superior power factor correction (PFC). In recent years, conduction loss and reverserecovery issues have been improved by the advanced power devices, and thus the converter’s efficiency and reliability are enhanced. Moreover, this converter topology has good potentiality for high-power applications. There are only two voltage sensors in both ac-side and dc-side for providing voltage information, which is an effective control strategy without current transducer. In addition, an equivalent singleswitch model of totem-pole boost PFC converter is offered that is an efficient approach to analyze the converter’s behaviors. Finally, some analytical results are given to evaluate the feasibility of the proposed current sensorless control method.

      • KCI등재

        Concrete compressive strength identification by impact-echo method

        Chi-Che Hung,Wei-Ting Lin,An Cheng,Kuang-Chih Pai 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.1

        A clear correlation exists between the compressive strength and elastic modulus of concrete. Unfortunately, determining the static elastic modulus requires destructive methods and determining the dynamic elastic modulus is greatly complicated by the shape and size of the specimens. This paper reports on a novel approach to the prediction of compressive strength in concrete cylinders using numerical calculations in conjunction with the impact-echo method. This non-destructive technique involves obtaining the speeds of P-waves and S-waves using correction factors through numerical calculation based on frequencies measured using the impact-echo method. This approach makes it possible to calculate the dynamic elastic modulus with relative ease, thereby enabling the prediction of compressive strength. Experiment results demonstrate the speed, convenience, and efficacy of the proposed method.

      • KCI등재

        Overview of systematic reviews with meta-analyses on acupuncture in post-stroke cognitive impairment and depression management

        Caroline Yik-fong Hung,Xin-yin Wu,Vincent Chi-ho Chung,Endy Chun-hung Tang,Justin Che-yuen Wu,Alexander Yuk-lun Lau 한국한의학연구원 2019 Integrative Medicine Research Vol.8 No.3

        Background: Acupuncture has been using as an alternative non-pharmacological therapy in the management of post stroke depression and cognitive impairment but its effectiveness and safety remain controversial. We conducted an overview of systematic reviews with meta-analyses to evaluate the evidence on the effect of acupuncture in the treatment of stroke with conventional medicine intervention. Methods: Systematic reviews summarized the treatment effects of acupuncture for post stroke cognitive impairment and post stroke depression were considered eligible. Methodological quality of included systematic reviews was assessed using A MeaSurement Tool to Assess systematic Reviews 2 (AMSTAR 2). Results: Four systematic reviews on post stroke cognitive impairment and ten systematic reviews on post stroke depression with good methodological quality were included. Meta-analyses revealed that acupuncture plus cognitive rehabilitation; and acupuncture or moxibustion plus cognitive rehabilitation, versus cognitive rehabilitation demonstrated statistically significant increase in Mini-Mental State Examination scores in compared to cognitive rehabilitation after 4 weeks treatment [Pooled weighted mean difference (WMD) = 3.14, 95% confidence interval (CI) = 2.06 to 4.21, I2 = 36%]; and (Pooled WMD = 3.22, 95% CI = 2.09 to 4.34, I2 = 0%). Furthermore, acupuncture versus antidepressant demonstrated statistically significant improve depression measured by increasing in 17-item Hamilton Depression Rating Scale in comparing to cognitive rehabilitation after 2 weeks treatment (Pooled WMD= -2.34, 95% CI= -3.46 to -1.22, I2 = 5%). Acupuncture usage was not associated with increased risk of adverse events. Conclusions: Acupuncture is safe and improves cognitive function and depressive disorder without obvious serious adverse events for post stroke patients.

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        Comparison of Short- and Long-term Hearing Outcomes of Successful Inlay Cartilage Tympanoplasty Between Small and Large Eardrum Perforations

        Pei-Wen Wu,Wen-Hung Wang,Chi-Che Huang,Ta-Jen Lee,Chien-Chia Huang 대한이비인후과학회 2015 Clinical and Experimental Otorhinolaryngology Vol.8 No.4

        Objectives. To compare the short- and long-term hearing outcomes after successful inlay cartilage tympanoplasty between patients with small (≤25%) and large (≥50%) eardrums perforations. Methods. This is a retrospective case series study conducted in a tertiary referral center. Twenty-five patients who underwent 27 procedures were enrolled. Their mean age was 60.26 years (range, 42 to 76 years). The mean follow-up time was 18.86 months (range, 12.30 to 35.83 months). The preoperative, initial postoperative, and long-term hearing results in patients with total repair of the eardrum were analyzed. Results. In the small size group, the average (±standard deviation) air-bone gap (ABG) closure was 1.08±7.53 dB in the short-term and 2.33±11.56 dB in the long-term hearing examinations. There was no difference between short- and long-term ABG closure (P=0.689). In the large size group, the average ABG closure was 9.77±9.40 dB in the short-term and 16.25±6.01 dB in the long-term hearing examinations. There was a significant difference between short- and long-term ABG closure (P=0.029). Conclusion. Patients with large perforations have continuous hearing improvement and ABG closure for more than one year. In contrast, the short- and long-term postoperative ABGs are almost the same in patients with small perforations. More long-term postoperative follow-up of hearing results is necessary for large perforations.

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        Bidirectional Hybrid DWDM-PON for HDTV/Gigabit Ethernet/CATV Applications

        Hai-Han Lu,Wen-Shing Tsai,Tzu-Shen Chien,Shih-Hung Chen,Yu-Chieh Chi,Che-Wei Liao 한국전자통신연구원 2007 ETRI Journal Vol.29 No.2

        A new scheme for bi-directional HDTV/Gigabit Ethernet/CATV transmission over a hybrid densewavelength- division-multiplexing passive optical network (DWDM-PON) is proposed and demonstrated. It is based on injection-locked vertical-cavity surface-emitting lasers and distributed-feedback laser diodes as transmitters. Services with 129 HDTV channels, a 1.25 Gbps Gigabit Ethernet connection, and 77 CATV channels are successfully demonstrated over 40 km single-mode fiber links. Good performance of bit error rate, carrier-to-noise ratio, composite second order, and composite triple beat is achieved in our proposed bidirectional DWDM-PON.

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