Korea Lift College

Mungyeong, South Korea

Korea Lift College

Mungyeong, South Korea
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Park S.,Korea Lift College | Cha G.,Soonchunhyang University
International Journal of Engineering Education | Year: 2013

In order tofind out the gapsinkey competencies, those of employeesinindustry and studentsincollege shouldbeanalyzed. Key competencies of students and technicians in automotive fields are scaled and compared to each other. Furthermore, the differences between two groups are analyzed to check on the gaps. Initial test sheets are reconstructed as an improved one after the prior assessment reflecting the opinion of industry to execute reliable level assessment. The area and level of key competencies are set up by literature analysis and consultation. The average scale of key competencies is assessed by students and technicians respectively. Numeracy, understanding organization, technology skill, problem-solving, interpersonal relation, communication skill, self-management and development, resource management and information application are selected as key competencies in Korea. Three levels of key competencies are set up. Key competencies of automotive college and industry are compared. Regardless of areas, the gaps between the two are significant shows a kind of discrepancy between industry and college requiring a scheme to fill the gaps. © 2013 TEMPUS Publications.

Song S.-G.,Korea Electronics Technology Institute | Park S.-M.,Korea Lift College | Park S.-J.,Chonnam National University
Journal of Power Electronics | Year: 2014

To increase the capacity of secondary cells, an appropriate serial composition of the battery modules is essential. The unbalance that may occur due to the series connection in such a serial composition is the main cause for declines in the efficiency and performance of batteries. Various studies have been conducted on the use of a passive or active topology to eliminate the unbalance from the series circuit of battery modules. Most topologies consist of a complex structure in which the Battery Management System (BMS) detects the voltage of each module and establishes the voltage balancing in the independent electrical power converters installed on each module by comparing the module voltage. This study proposes a new magnetic flux sharing type DC/DC converter topology in order to remove voltage unbalances from batteries. The proposed topology is characterized by a design in which all of the DC/DC convertor outputs connected to the modules converge into a single transformer. In this structure, by taking a form in which all of the battery balancing type converters share magnetic flux through a single harmonic wave transformer, all of the converter voltages automatically converge to the same voltage. This paper attempts to analyze the dynamic properties of the proposed circuit by using a Programmable Synthesizer Interface Module (PSIM), which is useful for power electronics analysis, while also attempting to demonstrate the validity of the proposed circuit through experimental results.

Ko J.-H.,Chonnam National University | Park S.-J.,Chonnam National University | Park S.-M.,Korea Lift College
Proceedings of the IEEE International Conference on Industrial Technology | Year: 2014

This research is purposed for the developing battery charger using the internal parameters - internal voltage of batteries and phase-which the existing charger don't use. For the research, the volume of applied voltage and current to batteries has been adjusted using direct connected capacity, and output voltage and current has been sensed. The sensed data go through the DFT, and DFT shows direct component, real, and imaginary numbers. Using these three values, internal voltage of batteries has been monitored. By monitoring the change of the internal voltage, the time which CV takes in ordinary ways can be reduced. Therefore, the quick charger can be developed. Simulation using Psim has been made to prove this idea, and stack has been developed to see the possibilities. © 2014 IEEE.

Le T.-V.,Chonnam National University | Park S.-M.,Korea Lift College | Park S.-J.,Chonnam National University | Yang J.-H.,Chonnam National University
2016 IEEE Transportation Electrification Conference and Expo, Asia-Pacific, ITEC Asia-Pacific 2016 | Year: 2016

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. © 2016 IEEE.

Jeong D.-W.,Chonnam National University | Kang F.-S.,Hanbat National University | Park S.-J.,Chonnam National University | Kim S.-P.,Chonnam National University | Park S.-M.,Korea Lift College
2016 IEEE Transportation Electrification Conference and Expo, Asia-Pacific, ITEC Asia-Pacific 2016 | Year: 2016

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. © 2016 IEEE.

Kim Y.,Soonchunhyang University | Ku M.,Soonchunhyang University | Cha G.,Soonchunhyang University | Park S.,Korea Lift College
IEEE Transactions on Applied Superconductivity | Year: 2011

In a magnet with pancake windings, inserting a gap between the pancake windings can increase the central magnetic field. This paper shows the optimized length of each gap is able to maximize the central magnetic field. Inserting a gap also improves field uniformity because the pancake windings are spread across a wider area. A high temperature superconducting (HTS) magnet consisting of BSCCO-2223 pancake windings was chosen for the calculation model to show the effectiveness of the proposed method. The E - J relation was used to determine the critical current, and an evolution strategy was adopted for the optimization of gap length. The results of calculations show that the critical current and the central magnetic field increased by 86.0% and 33.7%, respectively, for a magnet consisting of ten pancake windings. © 2010 IEEE.

PubMed | Dong - A University, Korea University, Keimyung University, Jeju National University and 2 more.
Type: Journal Article | Journal: Oncology reports | Year: 2016

Hwang-Heuk-San (HHS) is a polyherbal formulation that has been used in traditional Korean medicine for hundreds of years to treat gastrointestinal malignancy. However, to date, the mechanisms responsible for the anticancer effects remain unclear. In the present study, we investigated the anticancer effects of HHS using HCT116 human colorectal cancer (CRC) cells. Our results showed that HHS treatment significantly reduced cell survival and increased apoptotic cell death in a concentration-dependent manner. The treatment of HCT116 cells with HHS also significantly elevated the accumulation of reactive oxygen species (ROS), which was followed by the attenuation of the mitochondrial membrane potential through the upregulation of Bax and the downregulation of Bcl-2, which was accompanied by the release of cytochromec to the cytosol. In addition, HHS treatment caused the truncation of Bid and activated the caspases (caspase-8,-9and-3), which was associated with the induction of the Fas ligand, the death receptors (DRs), DR4 and DR5, downregulation of the inhibitors of protein expression in the apoptosis protein family, and the degradation of poly(ADP-ribose)-polymerase. However, a pan-caspase inhibitor reversed the HHS-induced apoptosis and growth suppression, indicating that HHS induces apoptosis though a caspase-dependent intrinsic and extrinsic apoptotic pathway in HCT116 cells. Moreover, HHS treatment inhibited the activation of phosphatidylinositol-3-kinase (PI3K)/Akt signaling, and a pharmacological inhibitor of PI3K significantly potentiated the apoptotic effects of HHS when employed in combination in HCT116 cells. Furthermore, the blocking of ROS generation by antioxidant N-acetyl cysteine attenuated the HHS-induced release of cytochromec, caspase activation and PI3K/Akt inactivation, thereby preventing HHS-induced apoptosis and reduction in cell viability. These findings suggest that HHS-induced ROS generation is required for caspase-dependent apoptotic cell death involving inhibition of the PI3K/Akt signaling pathway in HCT116 cells. Overall, our findings suggest that HHS may be an effective treatment for CRC cancer, and further studies are required to identify the active compounds in HHS.

PubMed | Korea University, Inje University, Jeju National University, Chonbuk National University and 3 more.
Type: | Journal: International journal of molecular medicine | Year: 2016

Esculetin, a coumarin derivative isolated from a variety of medicinal herbs, has been reported to possess multiple therapeutic and pharmacological actions. Although several studies have demonstrated the antioxidant activity of esculetin, its mechanisms of action have not been clearly established. The aim of this study was to evaluate the effects of esculetin against hydrogen peroxide(H2O2)induced oxidative stress in C2C12 myoblasts and to investigate the mechanisms involved in this process. Our data indicated that esculetin preconditioning significantly attenuated H2O2induced growth inhibition and DNA damage and the apoptosis of C2C12 cells by suppressing intracellular reactive oxygen species(ROS) accumulation. Treatment with esculetin effectively increased the phosphorylation of nuclear factor erythroid 2related factor 2(Nrf2) and the expression of NAD(P)H:quinone oxidoreductase1(NQO1). Esculetin treatment also activated extracellular signalregulated kinase(ERK), and pretreatment with PD98059, an ERKspecific inhibitor, blocked esculetin-mediated phosphorylation of Nrf2 and the induction of NQO1 expression. In addition, the protective effects of esculetin against H2O2induced ROS accumulation, apoptosis and growth inhibition were abrogated in the C2C12 cells pretreated with PD98059. Thus, the present study demonstrates that esculetin protects C2C12 cells against oxidative stress-induced injury, possibly through the activation of the Nrf2/NQO1 pathway.

Kim S.H.,Korea Lift College | Bae R.H.,KISWIRE Ltd. | Kwon J.D.,Yeungnam University
Journal of Mechanical Science and Technology | Year: 2012

Wire rope in elevators can become disconnected by tensile stress from friction between the rope and sheave, and by repeated stress including bending stress from various effects formed during contact between the rope and sheave. It is known that in designing wire rope, its strength is affected when wire disconnection occurs. However, insufficient related data is available. Therefore, fracture strength reduction and the effect of bending fatigue on wire rope life is difficult to evaluate. We considered the effects of wire rope diameter and tensile stress on fracture strength and wire rope life. We observed that fracture strength rapidly decreased when bending fatigue accumulated at the same time that the wire became disconnected. Moreover, bending fatigue was shown to be a crucial factor in decreased wire rope life. © 2012 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

Kim S.-H.,Korea Lift College | Ham S.-H.,KISWIRE Ltd. | Kwon J.-D.,Yeungnam University
Journal of Mechanical Science and Technology | Year: 2014

The corrosion of a wire rope reduces its life expectancy. In this study, repeated bending tests were conducted using a bending fatigue tester by changing the tensile load and corrosion time of wire ropes, which were the same type as those used in elevators. The number of broken wires was studied, and a tensile test was conducted for cases in which the fracture was severe. The effect of corrosion fatigue on life expectancy was considered by comparing fracture strength values and observing fracture surfaces. The results indicate that an increase in accumulated corrosion fatigue, a greater tensile load, and repeated bending cycles may yield a rapid decrease in fracture strength and an increase in the number of broken wires. Therefore, it is concluded that corrosion fatigue is an important factor that decreases the life expectancy of wire rope. © 2014 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

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