• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.399-402
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• 2006

This paper presents a new circuit topology of dc bus line switch-assisted half-bridge soft switching PWM inverter type dc-dc converter for arc welder. The proposed power converter is composed of typical voltage source half-bridge high frequency PWM inverter with a high frequency transformer link in addition to dc bus line side power semiconductor switching devices fer PWM control scheme and capacitive lossless snubbers. All the active power switches in the half-bridge arm and dc bus lines can achieve ZCS turn-on and ZVS turn-off commutation operation and consequently the total turn-off switching losses can be significantly reduced. As a result, a high switching frequency of using IGBTs can be actually selected more than about 20 kHz. The effectiveness of this new converter topology is proved for low voltage and large current dc-dc power supplies such as arc welder from a practical point of view.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.13-18
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• 2005

The variation of discharge characteristics of an ac PDP was observed with the charge of scan electrode driving circuit. Conventional scan electrode driving circuit provides two switches per one scan line, and the suggested one can be constituted by one switch per one scan line with the consideration of capacitive load characteristic of an ac PDP. To verify the workability of the suggested scheme, the performances of the ac PDP was investigated. The dynamic voltage margin was slightly decreased with the adoption of the suggested scheme, which is estimated to result from the misfiring of unselected discharge cells due to the deformation of voltage level of the neighboring scan electrode. In the observation of the delay characteristics of addressing discharge, the performances of the conventional circuit and the suggested one are assumed to be equivalent.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.9
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• pp.94-102
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• 2008

Capacitor switching is essential for the economic operation and proper voltage control of KOREA electric utility distribution system. Voltage transients produced by capacitor switching (around 2.0 per unit at substation and 2.5 or less per unit at customer site, and lasting less then 1[ms]) do not have the magnitude or duration to interfere with the operation of computers, but they do disrupt the operation of adjustable speed drivers. The result of our research, ASD manufacturers should learn from the computer industry and design products that will operate satisfactory In the electrical envelopment in which they will be placed. In this case history, the inductors on the input to ADSs in order to prevent nuisance tripping from capacitor switching(and other causes within the apartment) proved to be an effective, low-cost solution.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1271-1280
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• 2017

The android packer service using runtime execution compression technology switches to the original application using DexClassLoader. However the API interface of the DexClassLoader receives the path of the loaded DEX(Dalvik EXcutable) and the path of the compiled file. So there is a problem that the original file is exposed to the file system. Therefore, it is not safe to use the API for the packer service. In this paper, we solve this problem by changing the compile and load flow of the DexClassLoader API. Due to this changed execution flow, the complied file can be encrypted and stored in the file system or only in the memory and it can be decrypted or substituted at the time of subsequent loading to enable the original application conversion. we expected that the stability of the packer will increase beacause the proposed method does not expose the original file to the file system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.577-585
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• 2004

System Packet Interface Level 4 Phase(SPI-4.2) is an interface for packet and cell transfer between a physical layer(PHY) device and a link layer device, for aggregate bandwidths of OC-192 ATM and Packet Over Sonet/SDH(POS), as well as 10Gbps Ethernet applications. In this paper, we performs the research for SPI-4.2. Also we analyze the performance of SPI-4.2 interface module after modeling using C programming language. This paper shows that SPI-4.2 interface module with 512-word FIFO depth is able to be adapted for the offered loads to 97％ in random uniform traffic and 94％ in bursty traffic with bursty length 32. SPI-4.2 interface module can experience an performance degradation due to heavy overhead when it massively receives small size packets less than 14-byte. SPI-4.2 interface module is suited for line cards in gigabit/terabit routers, and optical cross-connect switches, and SONET/SDH-based transmission systems.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2512-2520
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• 1997

ITU-T Q.2931 and ATM Forum UNI 3.1 lead the standardization of signaling functions for the call/connection control at B-ISDN UNI. The one is applicable to the system in the public network, which provides the point-to-point call/connection control. The other is applicable to configure ATM private network mainly related with various terminal equipments. Domestic B-ISDN developers have developed ATM switches and B-NTs as network equipment, and B-TA as a terminal equipment. But many kinds of terminal-equipments are needed to provide various services in B-ISDN. If the public network can accommodate the terminal-equipments of UNI 3.1, it's very effective to accommodate manu kinds of terminal-equipments. Therefore, this paper identifies the problems that can be occurred on the signaling procedure, when B-ISDN the public network is connected to the UNI 3.1 terminal-equipment, and provides good alternatives that can handle this kind of call/connection well.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.216-220
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• 2013

The rated voltage has been rising in order to minimize the losses in power transmission. The high voltage electric machines should be minimized due to the constraints of space. Therefore, the temperature of high voltage electric apparatuses easily exceeds the temperature limits. In this paper, it is investigated that how to minimize the internal temperature rising of a high voltage switchgear by adjusting the arrangement of bus bars. High voltage switchgears consist of a circuit breaker, a CT, a PT, a earthing switches, bus bars, and so on. It is very difficult to estimate the electromagnetic properties of a high voltage switchgear due to these various environments and structures. In this paper, analyses are focused on the electromagnetic characteristics of bus bars according to the arrangement method and the enclosures to simplify the electromagnetic characteristics of a switchgear. It is found that the characteristics of electric field intensity and electromagnetic losses in bus bars are influenced by the arrangement method of bus bars. However, it is confirmed that the electromagnetic characteristics of enclosures are not affected by the arrangement of bus bars. In this paper, the arrangement methods of bus bars to minimize the electric field intensity and electromagnetic losses are suggested. It is expected that the research results are helpful to design and develop an electrically reliable high voltage switchgear.

• Molecules and Cells
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• v.39 no.1
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• pp.65-71
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• 2016

A challenge in the redox field is the elucidation of the molecular mechanisms, by which $H_2O_2$ mediates signal transduction in cells. This is relevant since redox pathways are disturbed in some pathologies. The transcription factor OxyR is the $H_2O_2$ sensor in bacteria, whereas Cys-based peroxidases are involved in the perception of this oxidant in eukaryotic cells. Three possible mechanisms may be involved in $H_2O_2$ signaling that are not mutually exclusive. In the simplest pathway, $H_2O_2$ signals through direct oxidation of the signaling protein, such as a phosphatase or a transcription factor. Although signaling proteins are frequently observed in the oxidized state in biological systems, in most cases their direct oxidation by $H_2O_2$ is too slow ($10^1M^{-1}s^{-1}$ range) to outcompete Cys-based peroxidases and glutathione. In some particular cellular compartments (such as vicinity of NADPH oxidases), it is possible that a signaling protein faces extremely high $H_2O_2$ concentrations, making the direct oxidation feasible. Alternatively, high $H_2O_2$ levels can hyperoxidize peroxiredoxins leading to local building up of $H_2O_2$ that then could oxidize a signaling protein (floodgate hypothesis). In a second model, $H_2O_2$ oxidizes Cys-based peroxidases that then through thiol-disulfide reshuffling would transmit the oxidized equivalents to the signaling protein. The third model of signaling is centered on the reducing substrate of Cys-based peroxidases that in most cases is thioredoxin. Is this model, peroxiredoxins would signal by modulating the thioredoxin redox status. More kinetic data is required to allow the identification of the complex network of thiol switches.

• Journal of Internet Computing and Services
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• v.10 no.6
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• pp.1-6
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• 2009

In this paper, we propose an energy efficient index scheme for Nearest Neighbor queries, specially designed for mobile P2P environments. we propose a PMBR (P2P Minimum Boundary Rectangle) index that provides the client with the ability of selective contacting and tuning from other nodes. The mobile client is able to identify whether or not the neighbor nodes have the desired information by accessing PMBR. Thus, the client immediately switches to change to another node's broadcast channel if the index does not contain the desired information. Furthermore, the client is able to predict the arrival time of the desired data items and only needs to tune into the broadcast channel when the requested data items arrives, by first accessing PMBR. Thus, the mobile client can stay in power save mode most of time, and tune into the broadcast channel only when the requested data items arrive. Experiments are conducted to evaluate the performance of the proposed scheme. Comprehensive experiments illustrate that the proposed scheme is more efficient than the previous techniques in terms of energy consumption.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_1
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• pp.115-124
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• 2020

In wireless power transfer (WPT) system, the conventional compensation topologies only can provide a constant current (CC) or constant voltage (CV) output under their resonant conditions. It is difficult to meet the CC and CV hybrid charging requirements without any other schemes. In this study, a switching hybrid topology (SHT) is proposed for CC and CV electric vehicle (EV) battery charging. By utilizing an additional capacitor and two AC switches (ACSs), a double-side LCC (DS-LCC) and an inductor and double capacitors-series (LCC-S) topologies are combined. According to the specified CC and CV charging profile, the CC and CV charging modes can be flexibly converted by the two additional ACSs. In addition, zero phase angle (ZPA) also can be achieved in both charging modes. In this method, because the operating frequency is fixed, without using PWM control, and only a small number of devices are added, it has the benefits of low-cost, easy-controllability and high efficiency. A 3.3-kW experimental prototype is configured to verify the proposed switching hybrid charger. The maximum DC efficiencies (at 3.3-kW) of the proposed SHT is 92.58%.