Seong-Mi Park

Effect of Lactobacillus acidophilus NS1 on plasma cholesterol levels in diet-induced obese mice

We investigated the probiotic properties of Lactobacillus acidophilus NS1, such as acid resistance, bile tolerance, adherence to HT-29 cells, and cholesterol assimilation activity. In an animal study, 7-wk-old male C57BL/6 mice were fed a normal diet, a high-fat diet (HFD), or an HFD with L. acidophilus NS1 (ca. 1.0×10(8) cfu/mL) for 10 wk. Total cholesterol and low-density lipoprotein (LDL) cholesterol levels were significantly lower in mice fed an HFD with L. acidophilus NS1 than in those fed an HFD only, whereas high-density lipoprotein cholesterol levels were similar between these 2 groups. To understand the mechanism of the cholesterol-lowering effect of L. acidophilus NS1 on the HFD-mediated increase in plasma cholesterol levels, we determined mRNA levels of genes involved in cholesterol homeostasis in the liver. Expression of sterol regulatory element-binding protein 2 (Srebp2) and LDL receptor (Ldlr) in the liver was dramatically reduced in mice fed a HFD compared with those fed a normal diet. When L. acidophilus NS1 was administered orally to HFD-fed mice, an HFD-induced suppression of Srebp2 and Ldlr expression in the liver was abolished. These results suggest that the oral administration of L. acidophilus NS1 to mice fed an HFD increased the expression of Srebp2 and Ldlr in the liver, which was inhibited by high fat intake, thus leading to a decrease in plasma cholesterol levels. Lactobacillus acidophilus NS1 could be a useful probiotic microorganism for cholesterol-lowering dairy products and the improvement of hyperlipidemia and hepatic lipid metabolism.

An effective machine learning algorithm using momentum scheduling

This paper proposes a new algorithm to improve learning performance in support vector machine by using the kernel relaxation and the dynamic momentum. Compared with the static momentum, the dynamic momentum is simultaneously obtained by the learning process of pattern weight and reflected into different momentum by the current state. Therefore, the proposed dynamic momentum algorithm can effectively control the convergence rate and performance. The experiment using SONAR data shows that the proposed algorithm has better convergence rate and performance than the kernel relaxation using static momentum.

Load-Sharing Algorithm using Digital Parallel Communication

In this paper, we proposes a new load-sharing algorithm with a ATmega2560 based digital communication. Proposed algorithm is different from conventional analog method. The high speed communication digital control is performed. To apply the digital communication and real-time control for time-sharing token bus method, we implemented high efficient load-sharing and redundancy. Also this system make down the price by auto ID algorithm and system response is improved by controller`s voltage and current integral value sharing. In parallel system prototype, each module have controller and performed load-sharing according to master module integral value. In this paper, we verify the validity of proposed algorithm using PSIM program and prototype.

A Study of Parallel Operation of Module Power using CAN Communication

In this paper, we proposes new load-sharing algorism for equal current division using CAN communication. Proposed algorithm is different from conventional analog method, it performed strong Load-sharing using bi-direction high speed communication. Each modules constitution on independence controller (voltage controller, electric current controller). In parallel system prototype, each module have controller and performed load-sharing according to master module integral value. Also additional controller use for getting each module situations that fault situation of module and fault locate of module . we implemented high efficient load-sharing and redundancy. In this paper, we verify the validity of proposed algorithm using PSIM program and prototype.

The old photovoltaic module detecting research

In this paper, we proposed a detection method for the old photovoltaic modules. The lifespan of general photovoltaic module is 20 years and PV modules installed since the 1990s is caused a failure because the PV module is a lifespan. So, way to detect such failure of PV modules is required. The proposed detection method has advantages that is easier and cheaper than the conventional method. To verify the validity of the proposed method, we carry out a computer-aided simulation.

Multilevel single-phase inverter based on TNPC-type

A new single-phase 7-level pulse-width modulation (PWM) inverter using T-type Neutral-point-clamped (TNPC) celIs is presented to obtain high quality output voltage minimizing the number of switching devices. It includes two TNPC cells series-connected together and connected to with different voltage levels. To avoid inherent problems caused by voltage unbalance, modified Buck-boost converters are added at DC-link side to make DC voltage sources for the proposed inverter. Operational principles and the switching pattern are analyzed in this paper. To verify the performance of the proposed inverter, PSIM simulation and experimental results are also shown in this paper.

High Efficiency H-Bridge Multilevel Inverter System Using Bidirectional Switches

This paper proposes new 13-level inverter topology and DC/DC converter buck-boost structure topology for multilevel, compounding uni-directional and bi-directional switches, and proposes high-efficient multilevel inverter system in which the proposed two PCS(Power Conditioning System) was connected in series. In proposed multilevel inverter of forming a output 13-level phase voltage by using total 18 switching parts, Then bi-directional switch has a characteristic of reducing conduction loss and controlling the reactive power effectively by separating electrically from the neutral point. DC/DC converter for supplying in dependent 3 DC voltage to the proposed multi-level inverter generates 180-degree phase shifted PWM by the symmetrically combined structure of 2 buck-boost converter and twice switching frequency efficiency can be obtained, meanwhile, the converter can step up/down the output voltage and 20% output can be generated comparing the input voltage. This proposed system is verified with the simulation and laboratory test.