• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.1
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• pp.19-26
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• 2016

In this study, a bidirectional DC-DC converter for idle stop and go (ISG) is developed to reduce fuel consumption. A three-phase non-isolated half-bridge converter is selected through a design method by considering efficiency and volume. According to the state of charge of the batteries at both the low-voltage and high-voltage sides, buck mode, which charges a low-voltage battery from the generated motor energy, and boost mode, which provides power to the motor from the low- and high-voltage battery sides, are required in the ISG system. Hence, an autonomous and seamless bidirectional control method using a variable current limiter is proposed for mode change. A 1.8 kW engineering sample of the proposed converter has been built and tested to verify the validity of the proposed concept. The maximum efficiencies, including gate driver and control circuit losses, are 96.4% in charging mode and 96.1% in discharging mode.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.930-937
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• 2013

In this paper, a motor control algorithm for performing a mode change without an integrated starter generator (ISG) is suggested for the automatic transmission-based hybrid electric vehicle (HEV). Dynamic models of the HEV powertrains such as engine, motor, and mode clutch are derived for the transient state during the mode change, and the HEV performance simulator is developed. Using the HEV performance bench tester, the characteristics of the mode clutch torque are measured and the motor torque required for the mode clutch synchronization is determined. Based on the dynamic models and the mode clutch torque, a motor torque control algorithm is presented for mode changes, and motor control without the ISG is investigated and compared with the existing ISG control.

• Journal of fish pathology
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• v.36 no.2
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• pp.213-228
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• 2023

We evaluated the transcriptional response of interferon (IFN)-related genes in rock bream iridovirus (RBIV)-infected rock bream under high-, low-, or no-mortality conditions induced by different stocking water temperatures. Under the high susceptibility condition (group A, water temperature 26℃, 100% mortality), only the Mx gene was expressed early, with prolonged expression, and with heavy viral loads of approximately 10⁶~10⁷ major capsid protein gene copies/μL from 4 to 10 days post infection (dpi). However, IRF1, IRF3, IRF8, STAT1, ISG15, PKR, Viperin, GVIN1, IFI44, and ISG56 were activated at later time points (8 dpi) and then quickly decreased (10 dpi). For the low susceptibility condition, the water temperature was set at 23℃ for 7 days (group B) and then reduced to 17℃. Group B exhibited a 28% mortality rate, in which persistent and effective antiviral responses were observed for long periods of time. In particular, at 20 and 22 dpi, when virus replication was peaked at approximately 10⁷/μL, the expressions of most of the IFN-related genes (IRF1, IRF3, IRF8, Mx, STAT1, ISG15, PKR, Viperin, GVIN1, IFI44, and ISG56) were significantly higher in group B than in the control group. Moreover, prolonged and higher levels of IRF3 (at least 30 dpi), IRF8 (at least 30 dpi), ISG15 (at least 30 dpi), PKR (at least 28 dpi), Viperin (at least 30 dpi), and IFI44 (at least 30 dpi) were also observed in the recovery stage of infection. Under the no-susceptibility condition at 17℃ (0% mortality), significantly elevated levels of IRF3, Mx, ISG15, and PKR were observed mostly until 20 dpi. The findings indicate that RBIV infection can induce an efficient IFN-mediated antiviral immune response in low- and no-susceptibility conditions. The findings could be valuable for effective control of viral pathogens in fish.

• Molecules and Cells
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• v.40 no.2
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• pp.83-89
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• 2017

Error-free replication and repair of DNA are pivotal to organisms for faithful transmission of their genetic information. Cells orchestrate complex signaling networks that sense and resolve DNA damage. Post-translational protein modifications by ubiquitin and ubiquitin-like proteins, including SUMO and NEDD8, are critically involved in DNA damage response (DDR) and DNA damage tolerance (DDT). The expression of interferon-stimulated gene 15 (ISG15), the first identified ubiquitin-like protein, has recently been shown to be induced under various DNA damage conditions, such as exposure to UV, camptothecin, and doxorubicin. Here we overview the recent findings on the role of ISG15 and its conjugation to target proteins (e.g., p53,$ {\Delta}Np63{\alpha}$, and PCNA) in the control of cellular responses to genotoxic stress, such as the inhibition of cell growth and tumorigenesis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1228-1233
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• 2013

In this paper, design of Wound Rotor Synchronous Motor(WRSM) for Integrated Starter and Generator(ISG) is performed based on Finite Element Analysis(FEA). WRSM can control not only magnitude and phase of armature current, but also field current. Thus, various control methods can be considered. Since driving characteristic of WRSM depends greatly on the control method, characteristic analysis accoding to possible driving current combination is reguired. Especially in high speed region, the control method that reduces unnecessary d-axis current by reducing field current is possible, which is similar to field weakening control. By the current combination reducing field and d-axis current, the design minimizing copper loss to increase efficiency on identical driving point is possible. In this paper, high efficient WRSM is designed applying the current combination which can minimize copper loss on each driving point.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.428-435
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• 2015

This paper presents the experimental study of cabin thermal comfort using a cold storage heat exchanger in a vehicle air-conditioning system. Recent vehicle-applied ISG functions for fuel economy and emission, but when vehicles stop, compressors in the air-conditioning system stop, and the cabin temperature sharply increases, making passengers feel thermal discomfort. This study conducts thermal comfort evaluation in the vehicle, which is applied to a cold storage system for the climate control wind tunnel test and the vehicle fleet road test with various airflow volume rates and ambient temperatures blowing to the cold storage heat exchanger. The experimental results, in the cold storage system, air discharge temperature is $3.1-4.2^{\circ}C$ lower than current air-conditioning system when the compressor stops and provides cold air for at least 38 extra seconds. In addition, the blowing airflow volume to the cold storage heat exchanger with various ambient temperature was examined for the control logic of the cold storage system, and in the results, the airflow volume rate is dominant over the outside temperature. For this study, a cold storage system is economically useful to keep the cabin at a thermally comfortable level during the short period when the engine stops in ISG vehicles.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.83-91
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• 2016

We studied the effect of battery deep cycle according to the way of active materials formation and the creation condition of electrode material, 3BS ($3PbO{\cdot}PbSO_4{\cdot}H_2O$) and 4BS ($4PbO{\cdot}PbSO_4$), in order to develop the batteries for Idle Stop & Go system. During the curing with active materials of anode and cathode, we found that the final creased active material was deformed by temperature control and it effects the durability of batteries. AGM battery and Flooded battery with 3BS active materials have excellent initial performance. And AGM battery with 4BS active materials shows the lower performance relatively. To compare and analyze of the formation efficiency of active materials, we tested the formation chagging steps with 3 steps and 9 steps differently. The results are that AGM battery with 4BS active materials is better on initial performance than AGM battery with 3BS. After the comparison of durability by DOD 17.5% life test, AGM battery is more suitable than flooded battery for the ISG system which needs the frequent deep cycle. In conclusion, AGM battery is the most suitable for ISG system and the life performance shows 80% difference according to the way of formation and curing of AGM batteries.

• Korean Journal of Materials Research
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• v.31 no.2
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• pp.75-83
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• 2021

To cope with automobile exhaust gas regulations, ISG (Idling Stop & Go) and charging control systems are applied to HEVs (Hybrid Electric Vehicle) for the purpose of improving fuel economy. These systems require quick charge/discharge performance at high current. To satisfy this characteristic, improvement of the positive electrode plate is studied to improve the charge/discharge process and performance of AGM(Absorbent Glass Mat) lead-acid batteries applied to ISG automotive systems. The bonding between grid and A.M (Active Material) can be improved by applying the Sand-Blasting method to provide roughness to the surface of the positive grid. When the Sand-Blasting method is applied with conditions of ball speed 1,000 rpm and conveyor speed 5 M/min, ideal bonding is achieved between grid and A.M. The positive plate of each condition is applied to the AGM LAB (Absorbent Glass Mat Lead Acid Battery); then, the performance and ISG life characteristics are tested by the vehicle battery test method. In CCA, which evaluates the starting performance at -18 ℃ and 30 ℃ with high current, the advanced AGM LAB improves about 25 %. At 0 ℃ CA (Charge Acceptance), the initial charging current of the advanced AGM LAB increases about 25 %. Improving the bonding between the grid and A.M. by roughening the grid surface improves the flow of current and lowers the resistance, which is considered to have a significant effect on the high current charging/discharging area. In a Standard of Battery Association of Japan (SBA) S0101 test, after 300 A discharge, the voltage of the advanced AGM LAB with the Sand-Blasting method grid was 0.059 V higher than that of untreated grid. As the cycle progresses, the gap widens to 0.13 V at the point of 10,800 cycles. As the bonding between grid and A.M. increases through the Sand Blasting method, the slope of the discharge voltage declines gradually as the cycle progresses, showing excellent battery life characteristics. It is believed that system will exhibit excellent characteristics in the vehicle environment of the ISG system, in which charge/discharge occurs over a short time.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.55-62
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• 2021

In order to improve fuel economy and reduce CO2, HEV adopts ISG system as a standard. This ISG system increased the electric load that the battery had to bear, and the number of starting increased rapidly. AGM Lead Acid batteries have been developed and used, but the charging time is about three times longer as the electrolyte amount control during formation must be maintained at a higher level compared to conventional lead-acid batteries. In this study, we tried to shorten the charging time by increasing the charging efficiency through the optimization of the formation pattern. In order to optimize the Formation Pattern, 10 charging steps and 6 discharging steps were applied to 16 multi steps, and the charging current for each step was controlled, and the test was conducted under 4 conditions (21 hr, 24 hr, 27 hr, 30 hr). As a result of simultaneous application of multi-step and discharge step, it was verified that minimizing the current loss and eliminating the sudden polarization during charging contributes to the improvement of charging efficiency. As a result, it showed excellent results in reducing the charging time by about 30 % with improved charging efficiency compared to the previous one.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.71-76
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• 2014

This Research focuses on how to maximize fuel economy improvement of I.S.G. while keeping 12V system. With 12V system the maximum gain of fuel economy with I.S.G. is known to be about 3~5% in FTP-75 mode because engine stop is only conducted in standstill idle. But in this study deceleration engine stop (engine speed is zero) has been tried additionally and the optimum condition for deceleration engine stop was found to maximize fuel economy improvement in practical point of view, the result of which is about 8.8% in FTP-75.