Bum-Jun Kim

Allergen-specific conventional immunotherapy decreases immunoglobulin E-mediated basophil histamine releasability

Background Allergen‐specific immunotherapy has proven to be clinically effective in the treatment of patients with atopic asthma; however, the mechanisms are still unclear. Several noted immunological changes include an increase of the allergen‐specific IgG antibody, a reduction in the allergen‐specific IgE antibody subsequent to transient increase, an allergen‐specific T cell shift in cytokine production from Th2 to Th1, and a decrease in quantity and activity of basophils and mast cells.

Analysis and design of current-fed two inductor bi-directional DC-DC converter using resonance for high efficiency and high step-up application

This paper proposes current-fed two-inductor bi-directional DC-DC converter using resonance(CF_TIBCR) for high efficiency and high step-up applications. Conventional dual half bridge(DHB) converter have problems of high voltage spikes and unavailable charge/discharge resulting from uni-directional converter. Hence, operating frequency and the efficiency are also limited. To solve these problems and achieve high efficiency, in this paper, the diode of the high voltage side is replaced by metal oxide semiconductor FET(MOSFET). All active switches undergo zero voltage switching(ZVS) condition. Especially, switches of the low voltage side are satisfied with zero current switching(ZCS) condition and ZVS condition. The steady state analysis and operation principle of CF_TIBCR is introduced. The DC voltage conversion ratio is derived based on steady state analysis. Simulation using PSIM is implemented to verify CF_TIBCR.

Modulation of the N-type calcium channel gene expression by the α subunit of Go

Abstract Go, a heterotrimeric G-protein, is enriched in brain and neuronal growth cones. Although several reports suggest that Go may be involved in modulation of neuronal differentiation, the precise role of Go is not clear. To investigate the function of Go in neuronal differentiation, we determined the effect of Goα, the α subunit of Go, on the expression of Cav2.2, the pore-forming unit of N-type calcium channels, at the transcription level. Treatment with cyclic AMP (cAMP), which triggers neurite outgrowth in neuroblastoma F11 cells, increased the mRNA level and the promoter activity of the Cav2.2 gene. Overexpression of Goα inhibited neurite extension in F11 cells and simultaneously repressed the stimulatory effect of cAMP on the Cav2.2 gene expression to the basal level. Targeted mutation of the Goα gene also increased the level of Cav2.2 in the brain. These results suggest that Go may regulate neuronal differentiation through modulation of gene expression of target genes such as N-type calcium channels.

Load and Source Battery Simulator Based on Z-Source Rectifier

This paper proposes a battery simulator (BS) based on a Z-source rectifier (ZSR), with the intention of emulating the discharge or charge characteristic of an actual lithium-polymer battery with high voltage and large capacity. The proposed BS is used for power testing for battery applications. The battery model, combined with a Shepherd model and a Thevenin model, is adopted to freely change the properties and specifications of the battery and to replicate the dynamic behavior of the battery, which is discretized to utilize the digital controller of the BS. The closed-loop voltage controller at the dc side of the ZSR is designed to emulate the rapid dynamic characteristics of the battery based on small-signal methods, considering the influence of the components of the impedance network. In this paper, battery voltage control algorithm (BVCA) is also utilized to minimize the voltage stress across switches while controlling two dc-side voltages within a wide range of output voltages. Simulation and experimental results are provided to verify the BS of the new feature and the proposed control method.

Control method of modular interleaved boost converter for SOC balancing in EV

This paper proposes control method of Differential Discharge Handling (DDH) modules with state of charge(SOC) balancing between battery modules in Electric Vehicle (EV) system. The DDH modules are composed of battery modules and converter modules. To achieve high efficiency, the diode is replaced by MOSFET to use the synchronous boost converter. In order to reduce the ripple of input/output voltage and current, it uses interleaved method. Interleaved converter operation is analyzed according to switching state by using state space averaging method. In order to design controller of the DDH converter, a control transfer function is obtained by using small signal modeling. The proposed SOC balancing algorithm maintains constant DC-link voltage and increases the utilization rate of the battery modules, as performing the discharge balancing between the modules by handling the discharge amount of the battery modules. Experimental results verify the proposed SOC balancing algorithm.

Current-fed two-inductor bi-directional DC/DC converter with wide output voltage range

The current-fed two-inductor boost converter (CF-TIBC) has previously been demonstrated to have advantages in operating low voltage and high current input applications. Such characteristics are suited for photovoltaic (PV) or battery application, likes energy storage system (ESS) or electric vehicle (EV). In this paper, the current-fed two-inductor bi-directional DC/DC converter (CF-TIBDC) is proposed. The proposed converter overcomes drawbacks of the conventional CF-TIBC, which are only one way power flow and voltage spike when the switches are turned off. By using the resonant components, the voltage spike problem is solved, and all switches in the CF-TIBDC meet the zero voltage switching (ZVS) condition. Likewise, the zero current switching (ZCS) condition is achieved through the switches on the low voltage stage. A wide range of output voltages with soft-switching is achieved by frequency-duty control. As a result, the proposed converter can maintain high efficiency across the entire range. The principles of the operation characteristics are presented with theoretical analysis, and the proposed converter is verified through PSIM simulation and experiment with a 300W laboratory prototype.

Multinomial model of droop control method for parallel-connected UPS inverters

In this paper, an advanced droop control using a multinomial model for operating the parallel-connected uninterruptible power supply (UPS) inverters is proposed. To control the parallel inverters without any physical communications, the control method using a P/Q droops is conventionally used. The conventional method droops voltage and frequency using the monomial model. In conventional droop control, the tradeoff between dynamic response and steady-stare error restricts the gradient of droop function. The proposed multinomial droop model has advantage of steady-state error by minimizing the tradeoff which is mentioned. The simulation results with MATLAB and PSIM are provided.

An enhanced control strategy for seamless transfer of grid-connected single-phase inverter in synchronous rotating frame

In this paper, a new control strategy for seamless mode transfer of grid-connected single-phase inverter is proposed. Generally, power flow between DC side and AC side is controlled by current reference of grid-connected inverter in d-q synchronous rotating frame. Therefore, it is general to reverse the current reference if the direction of power flow is changed. However, it causes a rapid change in current and aggravate the power quality of AC side. Therefore, this paper proposes an enhanced control strategy for seamless transfer in synchronous rotating frame. Theoretical analysis and simulation result demonstrate validity of the proposed control strategy.

Control strategy of shunt active power filter module to utilize regenerative energy of lift load

This paper deals with a control strategy of an active power filter module (APFM) which functions energy-saving by reusing regeneration energy of a traction motor for the lift load. The APFM can be used by additionally connecting dc-link of a usual inverter for motor of the lift load. In motoring mode, the deadbeat current control for APF function is used to mitigate delay factors depending upon data volume and interrupt processing of DSP associated with sampling time. The proposed method determines the operation mode and performs the control algorithm corresponding to each mode. The simulation is implemented to verify the proposed control method for APFM.

Control and design of the bi-directional DC/DC converter for fuel-cell stack diagnostic in FCEV

In this paper, control and design method of the fuel-cell (FC) stack diagnostic bi-directional converter are proposed. FC stack diagnostic converter is applied the bi-directional DC/DC converter for controlling the AC current. The AC current control is performed by applying the d-q transform for accurate current control. As a result, it can diagnose the status of the FC stack by supplying the AC current to the FC stack and monitoring the voltage and current of the FC stack. It is analyzed mathematically to design the bi-directional dc/de converter and considered the output ripple voltage and the inductor ripple current. The validity of proposed control method of the FC stack diagnostic bi-directional converter is verified by PSIM simulation results and proposed the 1.5kW FC stack diagnostic bi-directional converter.