• Journal of the Korean Ceramic Society
• /
• v.46 no.6
• /
• pp.648-652
• /
• 2009

Ceramic fiber separator is the promising material for thermal battery system because it reduces the production cost and offers the potential to a new application compared to a pellet type electrolyte. The electrolyte separator for thermal battery should be easily handled and loaded a large amount of the molten lithium salt. Ceramic fibers were used as an electrolyte separator and the lithium based molten salts were infiltrated into the ceramic filters. Leakage of molten salt (several lithium salts) leads to short-circuit during the thermal battery operation. In this study, a uniform and fine SiOC mat with fibers ranging from 1 to 3 ${\mu}m$ was obtained by electrospinning of polycarbosilane and pyrolysis. The optimum spinning conditions for obtaining fine diameters of SiOC fiber were controlled by the solution composition and concentration, applied voltage and spinning rate, release rate by porosity. The pore structures of the ceramic filter and the melting properties of the lithium salts affected to the electrolyte loading and leakage. The importance of the fiber size and porosity and their control was discussed and the mechanical properties were also discussed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.10
• /
• pp.733-738
• /
• 2017

In this study, we selected chlorine, a typical toxic material used in many workplaces, as the leakage material, and through the analysis of alternative scenarios based on the meteorological conditions in the summer frequently encountered in accidents, we suggest ways to improve the (method of analysis/accident scenario modeling). The analysis of 296 chemical accidents from January 2014 to December 2016 found that the highest rate of occurrence was in summer, accounting for 35.81% of the total. According to the risk assessment, the influence range and number of inhabitants in the influence area were 712.4 m and 20,090 under the annual mean weather conditions and 796.2 m and 27,143 people under the summer mean weather conditions, respectively. This result implies that, under certain conditions, the range of impacts in the current alternative scenario is incomplete. Therefore, risk assessment systems need to be improved in order to take into consideration the characteristics of each chemical substance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.12
• /
• pp.842-849
• /
• 2007

For a $CO_2$ two-stage twin rotary compressor used for heat pump water heater system, changes of $CO_2$ solubility in PAG oil were investigated along the gas passages from the first stage suction to final discharge. Only slight changes in solubility took place in suction chambers for both of the first and second stages, but for compression chambers, solubility variation ranged from 0.115 to 0.136, and from 0.133 to 0.182, respectively for the first and second stages. Calculation of gas flashing in parts of leakage oil flows and of oil contained in control volumes due to solubility changes was conducted and included in gas pressure calculation. For the second stage, gas flashing amounts to around $5%\sim6%$ for most leakage flows. Cooling capacity, compressor input, and COP obtained by calculation were well compared to the experimental results. Effects of operation speed on the compressor performance was also studied: as the shaft speed increased, adiabatic efficiency decreased rapidly due to increased over-compression loss.

• Journal of Digital Convergence
• /
• v.14 no.6
• /
• pp.253-261
• /
• 2016

As many people use internet through the various programs of PC and mobile devices, the possibility of private data leak is increasing. A program should be used after checking security of information flow. Security analysis of information flow is a method that analyzes security of information flow in program. If the information flow is secure, there is no leakage of personal information. If the information flow not secure, there may be a leakage of personal information. This paper proposes a method of analyzing information flow that facilitates SAT solver. The method translates a program that includes variables where security level is set into propositional formula representing control and information flow. The satisfiability of the formula translated is determined by using SAT solver. The security of program is represented through the result. Counter-example is generated if the program is not secure.

• Restorative Dentistry and Endodontics
• /
• v.26 no.5
• /
• pp.379-386
• /
• 2001

This study was performed to evaluate the sealing ability of various retrograde filling materials by using bacterial penetration and dye penetration test. One hundred and forty extracted human teeth with single, straight canals and mature apiece were collected and used for this study. All canals were instrumented using an engine driven Ni-Ti file (ProFile). After removing 3mm from the apex of tooth, a standardized 3mm root end cavity was prepared using an ultrasonic instrument. The 70 teeth were randomly divided into 7 groups : 6 groups for retrograde filling using Super-EBA, ZOE, Chelon-Silver, IRM, ZPC and amalgam. The 7th group was used as a negative control. Nail varnish was applied to all external root surfaces to the level of the reseated root ends to prevent lateral microleakages. The specimens were then sterilized in an ethylene oxide sterilizer for 24 hours. 2 mm of the reseated root was immersed in a culture chamber containing a Tripticase Soy Broth with a phenol red indicator. The coronal access of each specimen was inoculated every 72 hours with suspension of Proteus vulgaris. The culture media were observed every 24hours for color change indicating bacterial contamination. The specimens were observed for 4weeks. The remaining 70 teeth were submitted to a dye penetration test. The canals of all teeth were first sealed with AH26 and obturated using an Obtura II system. Root resection, root end preparation and retrograde filling was performed as above. All specimens were suspended in 2% methylene blue dye for 72 hours before being ion gitudinally split. The degree of dye penetration was then measured using a stereomicroscope at 10 magnification and evaluated. The results were as floows : 1. In the bacterial penetration, the degree of leakage was the lowest in the Super-EBA, followed by, in ascending order, ZOE, Chelon-Silver IRM and ZPC. The amalgam showed highest bacterial leakage of all(p<0.01). 2. In the dye penetration, the degree of microleakage was the lowest in the Chelon-Silver and Super-EBA, followed by, in ascending order, IRM, ZPC. The ZOE and amalgam showed the highest microleakage of all (p<0.05). These results suggested that the eugenol based cement, Super-EBA, have excellent sealing ability as a retrograde filling material.

• Fire Science and Engineering
• /
• v.33 no.4
• /
• pp.121-129
• /
• 2019

The Chemical Control Act of 2015 was enhanced to ensure the safe management of hazardous chemicals. In particular, there have been substantial changes in the standards for the installation and management of handling facilities for manufacturing and storing hazardous chemicals. However, some standards for handling facilities are difficult to implement due to a lack of physical space or because of safety accidents during facility improvements. Therefore, the Safety assessment system (SAS) has been operating for such facilities since 2018. This study developed a leakage trajectory evaluation module that can easily evaluate the outside of a dike for safety evaluation. We analyzed two case studies on a dike for hydrochloric acid and sulfuric acid storage tanks with this module and suggest a reasonable plan for the facility. We believe that it will be possible to more easily submit SAS reports at chemical plants by using this evaluation module. This study is expected to contribute to the improvement of the safety design of hazardous chemical handling facilities.

• Journal of the Korean Institute of Gas
• /
• v.20 no.4
• /
• pp.25-32
• /
• 2016

The purpose of this study is safety evaluation of solar energy generation which is installed on the canopy at the LPG filling station. in case of a gas station, the solar energy generation was become legalization through a related law reform in 2008. Also, in case of a LPG filling station, the solar energy generation was become legalization through a related law reform in 2015. So, the related law that KGS CODE and Safety control of dangerous substances law and the case of installed solar energy generation in gas, LPG filling station was investigated. two scenarios are supposed for the CFD. Release of safety valve pipeline and ruptured dispenser leakage are the scenarios. The FLACS which developed GexCon in Norway was used for simulation. LPG dispersion to the upper side of canopy was very small with safety distance.

• Journal of the Korean Institute of Gas
• /
• v.24 no.2
• /
• pp.29-35
• /
• 2020

The Chemical Control Act has revised in 2015 to promote chemical safety, particularly enhancing the standards for the installation and management of hazardous chemical handling facilities. However, in some existing facilities, it was difficult to comply with some facility standards because of lack of land, safety accident possibility during rebuilding. In this study, we attempted to provide a more rational approach of dike standard which was the highest(2017: 117, 2018: 83) complaint for two years(2017~2018, 1,087) by prior study, FLACS simulation, analyze safety management standard and conduct a survey. Therefore, considering the purpose of installing the discharge wall only at existing facilities in operation, additional sensors that can detect chemical leakage and leakage were recognized as an additional alternative to installing and operating closed circuit television (CCTV). This will help the safety and cost aspects of small or medium-sized businesses or small and medium-sized enterprises that cannot secure legal grounds or fail to enforce legal regulations due to economic problems such as construction costs.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.5
• /
• pp.55-62
• /
• 2019

In this paper, we consider K-user multiple-input multiple-output (MIMO) interference channel and present a transceiver design for simultaneous wireless information and power transfer (SWIPT) systems. In addition, we consider a SWIPT system where an information decoding receiver and an energy harvesting receiver are co-located at the same receiver. In the proposed scheme, signal-to-leakage plus noise ratio (SLNR) is used as a cost function and a transceiver is designed to satisfy the threshold of the harvested energy. More specifically, transmitter precoding vector, receiver filter vector, and power spitting factor are simultaneously designed to maximize SLNR with a constraint on the harvested energy. Through computer simulation, we compare the signal-to-interference plus noise ratio (SINR) performance of the proposed and conventional schemes. When a special condition among the number of transmit antennas, receive antennas, and users is satisfied, the proposed scheme showed better SINR performance than the conventional scheme at low signal-to-noise ratio (SNR) range. Also, when the condition is not satisfied, the proposed scheme showed better performance than the conventional scheme at all SNR range.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.4
• /
• pp.193-201
• /
• 2015

Corporation's valuable intelligent asset is being threatened from the skills of threatening subject that has been evolved along with the growth of the information system and the amount of the information asset. Domestically, attempts of various private information attacks, important information extortion, and information damage have been detected, and some of them have abused the vulnerability of security of information system, and have become a severe social problem that generates security incident. When accessing to the security, most of companies used to establish a strategy with a consistent manner and a solution plan. However, this is not a proper way. The order of priorities vary depending on the types of business. Also, the scale of damage varies significantly depending on the types of security incidents. And method of reaction and critical control point vary depending on the types of business and security incidents. In this study, I will define the security incidents by their types and preponderantly examine how one should react to those security incidents. In this study, analyzed many types of security accidents that can occur within a corporation and an organization considering various factors. Through this analysis, thought about factors that has to be considered by corporations and organizations when they intend to access to the information security. This study focuses on the response methodology based on the analysis of the case analysis of the leakage of industrial secret and private secret other than the conceptual response methodology that examines the way to prevent the leakage of the industry security systems and the industry information activities. And based on these factors, want to be of help for corporations to apply a reasonable approach when they establish a strategy to information security.