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A simple, fast and highly sensitive assay for the detection of telomerase activity
Quach, Quang Huy,Jung, Juyeon,Kim, Hyeran,Chung, Bong Hyun The Royal Society of Chemistry 2013 Chemical communications Vol.49 No.59
<P>A highly sensitive and rapid PCR-free telomerase activity assay has been developed that uses SYBR Green intercalation into the G-quadruplex structures in the presence of K<SUP>+</SUP>.</P> <P>Graphic Abstract</P><P>A PCR-free, highly sensitive and rapid assay to convert telomerase activity into fluorescence signals using SYBR Green has been developed. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cc42571a'> </P>
Harmonic Analysis of a Modular Multilevel Converter Using Double Fourier Series
Quach, Ngoc-Thinh,Chae, Sang Heon,Ahn, Jin Hong,Kim, Eel-Hwan The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.1
This paper presents a harmonic analysis of the modular multilevel converter (MMC) using a double Fourier series (DFS) algorithm. First, the application of DFS for harmonic calculation in the MMC is made by considering the effect of arm inductor. The analytical results are then confirmed by comparing with the simulation results of using the fast Fourier transform (FFT) algorithm. Finally, distribution of harmonics and total harmonic distortion (THD) in the MMC will be analyzed in three cases: harmonics versus number of levels of MMC, harmonics versus total switching frequency and harmonics versus modulation index. The simulation results are performed in the PSCAD/EMTDC simulation program in order to verify the analytical results obtained by Matlab programming.
Quach, Huu Luong,Kim, Ji Hyung,Hyeon, Chang Ju,Chae, Yoon Seok,Moon, Jae Hyung,Kim, Ho Min The Korea Institute of Applied Superconductivity a 2018 한국초전도저온공학회논문지 Vol.20 No.1
The thermal and electrical properties of the conductor are critical parametersfor the design and optimization of the superconducting magnet. This paper presents simulation code to analyze electrical and thermal stability characteristics of the second generation (2G) high-temperature superconductor (HTS) by varying copper stabilizer thickness. Two types of commercial 2G HTS coated conductor tapes, YBCO and GdBCO were used in this study. These samples were cooled by Liquid Nitrogen ($LN_2$) having boiling at 77.3 K and an equivalent electrical circuit model for them is choosen and analysed in details. Also, an over-current pulse test in which a current exceeding a critical current was performed. From the simulation results, the influences of the copper stabilizer thickness on the stability characteristics of these samples are presented.
Quach Nhu Y(콱누이),Ock-Taeck Lim(임옥택) 한국자동차공학회 2024 한국자동차공학회 부문종합 학술대회 Vol.2024 No.6
The influence of heating value on combustion characteristics in an experimental engine setup has been meticulously examined in this study. A comprehensive analysis of engine performance parameters, including residual gas concentrations, effective release energy, brake mean effective pressure (BMEP), brake specific fuel consumption (BSFC), engine brake torque, and engine power, was conducted under varying heating values. An experimental system is installed with a dynamo testing system, and a simulation model is established using AVL-Boost software. In this research, the ignition timing is increased from a 10 degree to 40 degree crank angle bTDC. The engine testing speed band is from 3000 rpm – 10000 rpm. The findings revealed a nuanced interplay between heating value and combustion completeness, with a critical threshold at 35 degrees ignition timing. Notably, the highest residual gas concentrations were consistently observed at 35 degrees, indicating incomplete combustion. Conversely, combustion completeness improved at 20 degrees, accentuated by the pivotal role of heating value. Effective release energy exhibited a consistent increase up to 30 degrees ignition timing, underscoring the intricate relationship between ignition timing and energy release. BMEP peaked at 30 degrees across all heating values, with heating value significantly augmenting combustion efficiency. Conversely, BMEP reached its nadir at 35 degrees. BSFC displayed optimal combustion efficiency at 25 degrees. The engine demonstrated maximum brake torque and power at specific heating values and ignition timings.
Quach, Hung,Kim, Jin-Jae,Nguyen, Duc-Toan,Kim, Young-Suk Elsevier 2020 International journal of mechanical sciences Vol.169 No.-
<P><B>Abstract</B></P> <P>A new phenomenological ductile fracture criterion that is proposed. The proposed model is associated with the micro mechanisms of void nucleation, void growth, and evolution of void coalescence. The secondary voids band and rotation of voids effect are considered in the new ductile fracture criterion. A series of upsetting test results of aluminum 2024-T351 and TRIP RA-K40/70 steel are used to construct and compare the accuracy of fracture locus proposed by new ductile fracture criterion, Modified Mohr-Coulomb criterion and extend Lou-Huh criterion. The fracture locus constructed using the proposed criterion is close to the experimental data points over a wide stress state range from uniaxial compression to balanced biaxial tension. Then, a series of upsetting tests and square cup drawing tests are conducted with Al6014-T4 to evaluate the accuracy of the proposed criterion. All results indicate that the proposed ductile fracture criterion can be utilized for predicting initial fracture in sheet metal forming.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new phenomenological ductile fracture criterion considering micro mechanisms of void nucleation, void growth, and evolution of void coalescence is presented in this paper. </LI> <LI> The secondary voids band and rotation of voids effect are considered in the new ductile fracture criterion. </LI> <LI> The new ductile fracture criterion can be utilized for predicting initial fracture in sheet metal forming with lager range of stress triaxiality. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
The Harmonic Current Mitigation of DFIG under Unbalanced Grid Voltage and Non-linear Load Conditions
Quach Ngoc Thinh,Eel-Hwan Kim(김일환) 전력전자학회 2011 전력전자학술대회 논문집 Vol.2011 No.7
This paper presents an analysis and a novel strategy for a doubly fed induction generator (DFIG) based wind energy conversion system under unbalanced grid voltage and non-linear load conditions. A proportional-resonant (PR) current controller is applied in both grid side converter (GSC) and rotor side converter (RSC). The RSC is controlled to mitigate the stator active power and the rotor current oscillations at double supply frequency under unbalanced grid voltage while the GSC is controlled to mitigate ripples in the dc-link voltage and compensate harmonic components of the network current. Simulation results using Psim simulation program are presented for a 2 ㎿ DFIG to confirm the effectiveness of the proposed control strategy.
Analyzing Stability of Jeju Island Power System with Modular Multilevel Converter Based HVDC System
Quach, Ngoc-Thinh,Lee, Do Heon,Kim, Ho-Chan,Kim, Eel-Hwan The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.1
This paper proposes the installation of a new modular multilevel converter based high-voltage direct current (MMC-HVDC) system to connect between mainland and Jeju island power systems in Korea in 2020. The purpose is to combine with two old line-commutated converters (LCC)-based HVDC system to achieve a stability of the Jeju island power system. The operation of the overall system will be analyzed in three cases: (i) wind speed is variable, (ii) either one of the LCC-HVDC systems is shutdown because of a fault or overhaul, (iii) a short circuit fault occurs at the mainland side. The effectiveness of the proposed control method is confirmed by the simulation results based on a PSCAD/EMTDC simulation program.
Frequency and Voltage Control Strategies of the Jeju Island Power System Based on MMC-HVDC Systems
Quach, Ngoc-Thinh,Chae, Sang Heon,Song, Seung-Ho,Kim, Eel-Hwan The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1
At present, one of two LCC-HVDC systems is responsible for controlling the grid frequency of the Jeju Island Power System (JIPS). The grid voltage is regulated by using STATCOMs. However, these two objectives can be achieved in one device that is called by a modular multilevel converter-high voltage direct current (MMC-HVDC) system. Therefore, this paper proposes frequency and voltage control strategies for the JIPS based on a MMC-HVDC system. In this case, the ancillary frequency and voltage controllers are implemented into the MMC-HVDC system. The modelling of the JIPS is done based on the parameters and measured data from the real JIPS. The simulation results obtained from the PSCAD/EMTDC simulation program are confirmed by comparing them to measured data from the real JIPS. Then, the effect of the MMC-HVDC system on the JIPS will be tested in many cases of operation when the JIPS operates with and without STATCOMs. The objective is to demonstrate the effectiveness of the proposed control strategy.