• Journal of the Korean Society of Safety
• /
• v.13 no.3
• /
• pp.67-73
• /
• 1998

The technology for neutralizing static electricity by soft X-ray radiation has been newly developed. This technology involves ionization of gas molecules in the vicinity of a charged substrate to generate ions and electrons to reduce electrostatic potential. The ULSI device substrate and liquid crystal display substrate tend to get charged instantly to a high potential level when they are handled in the manufacturing process. Soft X-ray radiation is adequate in air or $O_2$ gas at atmospheric pressure. This newly developed neutralization method is effective to be superior to the conventional technique, i.e., an ionizer by using corona discharge ,in every aspect. The new method features excellent neutralization capability and is able to completely reduce electrostatic potential to 0 V within a short time. Moreover, this is a very clean antistatic technology free from particle generation ,ozone generation, and electromagnetic noise, which are problems in using the corona discharge ionizer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.601-604
• /
• 2001

The insulation materials of cables used for underground power transmission requires a higher insulating capability, and the most popular method to examine the cable is partial discharge test due to applying variation voltage. In the thesis, air void, silicone oil, of which may possibly exist real cables, are simulated by Electro 2D program. Also the relations between calculated field strength and the void defect type in the cable joint materials. In the modeling, eclectic field inner to the cable joint material composed by XLPE and EPDM is modeling simulated. We obtained the electric field distribution in void due to two conditions.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.4 no.5
• /
• pp.405-412
• /
• 1999

Meta! Halide Discharge(]\1HD) Iamps have good color rendition, long life and good focusing capability but h have flickers bv acoustic resonances. We have designed the electronic ballast for reducing acoustic resonances in high pressure discharge tube. The ballast consists of main two parts, the first part is a half-bridge inverter to make a square wave form a and the st'Cond part is a flyback converter to combine the low frequency and high frequency component. As a r result of this study, we conclude that MHD lamps of 70 watt 따c very well light(D without acoustic resonance p phenomena by the elestronic ballast.

• Journal of Hydrogen and New Energy
• /
• v.2 no.1
• /
• pp.15-21
• /
• 1990

Nickel-hydrogen battery systems with metal hydride alloys are expected to have both higher energy density and lower pollution than nickel-cadmium cells. Nickel-hydrogen storage cells are expected to be well-suited for use in space crafts for a large capacity power storage system. Their major advantages are not only a capability of deep DOD(depth of discharge) using but also with excellent durability under excessive overcharging and overdischarging. In this study, the charge/discharge capacities, anodic polarization characteristics and durability for the continious charge/diacharge cycling of the $Ti_{1-X}Zr_XVNi$ and $Ti_{1-X}Zr_XV_{0.5}Ni_{1.5}$ alloys were measured by electrochemical method. The electrode properties of the copper or nickel plated $Ti_{1-X}Zr_XV_{0.5}Ni_{1.5}$ alloys were examined with a battery charge/discharge testing system in the temperature range of -5 to $25^{\circ}C$.

• Journal of Electrochemical Science and Technology
• /
• v.2 no.1
• /
• pp.51-56
• /
• 2011

We develop a new nonwoven composite separator for a safer lithium-ion battery, which is based on coating of silica ($SiO_2$) colloidal particles/styrene-butadiene rubber (SBR) binder to a poly(ethylene terephthalate) (PET) nonwoven support. The $SiO_2$ particles are interconnected by the SBR binder and closely packed in the nonwoven composite separator, which thus allows for the development of unusual porous structure, i.e. highly-connected interstitial voids formed between the $SiO_2$ particles. The PET nonwoven serves as a mechanical support that contributes to suppressing thermal shrinkage of the nonwoven composite separator. The $SiO_2$/SBR content in the nonwoven composite separators plays an important role in determining their separator properties. Porous structure, air permeability, and electrolyte wettability of the nonwoven composite separators, in comparison to a commercialized polyethylene (PE) separator, are elucidated as a function of the $SiO_2$/SBR content. Based on this understanding of the nonwoven composite separators, the effect of $SiO_2$/SBR content on the electrochemical performances such as self-discharge, discharge capacity, and discharge C-rate capability of cells assembled with the nonwoven composite separators is investigated.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.4
• /
• pp.635-640
• /
• 2008

New gas mixtures are now finding applications such as interrupting media for high-voltage circuit breakers. These mixtures consist of a high content of carbon tetrafluoride($CF_4$) added to sulfur hexafluoride($SF_6$). Nowdays $SF_6$ has been established for the use in gas insulated substations due to its high insulation withstand level and good arc quenching capability. At this paper Breakdown characteristics were investigated for $SF_6/CF_4$ mixtures when AC voltage and standard lightning impulse voltage(LI) was applied in a needle-plane electrodes. And partial discharge(PD) experiments were carried out in the test chamber which was made in needle-plane electrode. And ${\Phi}$-Q-N distribution of partial discharge signals was analyzed. The total pressure of the $SF_6/CF_4$ mixtures was varied within the range of 0.1-0.5 Mpa in the test chamber. The breakdown voltage in needle-plane electrode displayed N shape characteristics for increasing the content of $SF_6$ at positive impulse voltage and the PD inception voltage was increased slightly when pressure of $SF_6/CF_4$ Mixtures was increased. Maximum PD inception voltage is showed in 80% SF6/20%$CF_4$.

• Nuclear Engineering and Technology
• /
• v.46 no.1
• /
• pp.39-46
• /
• 2014

A total loss of all heat sinks is considered a severe accident with a low probability of occurrence. Following a total loss of all heat sinks, the degasser/condenser relief valves (DCRV) become the sole means available for the depressurization of the primary heat transport system. If a nuclear power plant has a total loss of heat sinks accident, high-temperature steam and differential pressure between the primary heat transport system (PHTS) and the steam generator (SG) secondary side can cause a SG tube creep rupture. To protect the PHTS during a total loss of all heat sinks accident, a sufficient depressurization capability of the degasser/condenser relief valve and the SG tube integrity is very important. Therefore, an accurate estimation of the discharge through these valves is necessary to assess the impact of the PHTS overprotection and the SG tube integrity of the primary circuit. This paper describes the analysis of DCRV discharge capacity and the SG tube integrity under a total loss of all heat sink using the CATHENA code. It was found that the DCRV's discharge capacity is enough to protect the overpressure in the PHTS, and the SG tube integrity is maintained in a total loss of all heat accident.

• Korean Chemical Engineering Research
• /
• v.57 no.4
• /
• pp.547-552
• /
• 2019

Electrochemical properties of $LiMn_{0.8}Fe_{0.2}PO_4$ cathode were investigated with gel polymer electrolyte (GPE). To access fast and efficient transport of ions and electrons during the charge/discharge process, a pure and well-crystallized $LiMn_{0.8}Fe_{0.2}PO_4$ cathode material was directly synthesized via spray-pyrolysis method. For high operation voltage, polyacrylonitrile (PAN)-based gel polymer electrolyte was then prepared by electrospinning process. The gel polymer electrolyte showed high ionic conductivity of $2.9{\times}10^{-3}S\;cm^{-1}$ at $25^{\circ}C$ and good electrochemical stability. $Li/GEP/LiMn_{0.8}Fe_{0.2}PO_4$ cell delivered a discharge capacity of $159mAh\;g^{-1}$ at 0.1 C rate that was close to the theoretical value ($170mAh\;g^{-1}$). The cell allows stable cycle performance (99.3% capacity retention) with discharge capacity of $133.5mAh\;g^{-1}$ for over 300 cycles at 1 C rate and exhibits high rate-capability. PAN-based gel polymer is a suitable electrolyte for application in $LiMn_{0.8}Fe_{0.2}PO_4/Li$ batteries with perspective in high energy density and safety.

• Journal of Korean Critical Care Nursing
• /
• v.11 no.3
• /
• pp.45-57
• /
• 2018

Purpose : This study was performed to identify the influencing factors of unplanned intensive care unit (ICU) readmission. Methods : The study adopted a Rretrospective case control cohort design. Data were collected from the electronic medical records of 844 patients who had been discharged from the ICUs of a university hospital in Incheon from June 2014 to December 2014. Results : The study found the unplanned ICU readmission rate was to be 6.4%(n=54). From the univariate analysis revealed that, major symptoms at $1^{st}$ ICU admission, severity at $1^{st}$ ICU admission (CPSCS and APACHE II), duration of applying ventilator application during $1^{st}$ ICU admission, severity at $1^{st}$ discharge from ICU (CPSCS, APACHE II, and GCS), and application of $FiO_2$ with oxygen therapy, implementation of sputum expectoration methods, and length of stay of ICU at $1^{st}$ ICU discharge were appeared to be significant; further, decision tree model analysis revealed that while only 4 variables (sputum expectoration methods, length of stay of ICU, $FiO_2$ with oxygen therapy at $1^{st}$ ICU discharge, and major symptoms at $1^{st}$ ICU admission) were shown to be significant. Conclusions : Since sputum expectoration method was the most important factor to predictor of unplanned ICU readmission, a assessment tool for the patients' capability of sputum expectoration needs to should be developed and implemented, and standardized ICU discharge criteria, including the factors identified from the by empirical evidences, might should be developed to decrease the unplanned ICU readmission rate.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2002.11a
• /
• pp.105-109
• /
• 2002

A TVS and Varistor are preservative equipment against electro static discharge(ESD). We use a TVS for I/O protection of a circuit which has faster response time than a Varistor. And a Varistor has large power capability, therefore, which be used in input stage for internal pressure prevention. This paper will compare a TVS with a Varistor with respect to response characteristic to ESD in DC 24[V] low voltage circuit.