• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.473-476
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• 2008

Due to the pursuit of high function and international price increase in the field of construction, the application of the secondary product using cement is on the increase gradually in the construction industry in the pursuit of economic cost reduction by the shortening of the construction time like Expediting and the dry construction method at the same time. However, it is in very urgent situation of measures to improve the structural performance or durable performance because it is limited for use in terms of panel in interior exterior building or functional repair reinforce as yet. Accordingly, this study is to investigate applicability of permanent Formwork like mould with the structural performance or excellent durable performance in the field of construction, and to derive optimum mixture in the performance and quality of manufacture. As a result of analysis comparison with the dynamic and durable properties of vacuum extrusion molding high toughness cement panel according to the mixture of four conditions, this study has found that the test body of mixing ECC-DP3 using small filler and large granulated blast furnace slag and powder flame retardant had excellent relative hardness and bending stress strain. The durable performance has shown excellent tendency by the decrease of porosity and enhancement of water-tightness.

• Composites Research
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• v.31 no.4
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• pp.133-138
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• 2018

Polymer foams were used to fill the void in the structure in addition to flame retardant and heat insulation. Polymer foams such as polyurethane, polyisocyanurate, poly(vinyl chloride), polyethylene terephthalate were used to weight lighting materials. In this study, epoxy foam was used to improve mechanical properties of polymer foam. Acid anhydride type hardener reacts with polyol. Using this phenomenon, if blowing agent was added into epoxy resin using acid anhydride type hardener, formation and compressive properties of epoxy foam was studied. Formation of polymer foam was compared with type of blowing agent and concentration of blowing agent via compressive test. As these results, optimized condition of epoxy foam was found and epoxy foam had better compressive property than other polymer foam.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.129-136
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• 2020

A Cut Out Switch (COS) is used for line protection and pole transformer protection in power systems. The COS used to protect the pole transformer is installed on the power side of the pole transformer to protect the electric equipment from fault currents. The COS is composed largely of a body and a fuse holder, and when the fault current is energized, the element of the fuse link in the fuse holder is melted to block the fault current. The arc generated when the COS fuse link is blown causes fire and noise, causing discomfort to residents in the surrounding area, and the arc flame can cause secondary damage to the peripheral device. In this study, a current-limiting COS fuse with improved overcurrent blocking performance rather than explosion type was developed to solve the arc and noise problems during COS operation. The overcurrent breaking performance of the current-limiting COS improves the reliability by developing a striker and COS fuse bracket. In addition, this study aimed to verify the performance of the developed current-limiting COS fuse through a test at an authorized institution.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.889-892
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• 2005

Standardized method based on extraction, filtration, and gas chromatography (GC) was developed far propylene glycol analysis to set hygienic norm of safety measure for foods under governmental control. Various columns were tested fur propylene glycol analysis by GC with flame ionization detector. Known amount of propylene glycol was spiked into wheat flour dough and analyzed by developed method. Results showed 101.60% recovery rate for propylene glycol with HP-5 column. Reproducibility test of standards recorded 0.30 for standard variation and 0,42% for relative variation. Using analytical method established, contents of propylene glycol in more than hundred different foods were monitored. Propylene glycol was detected in most foods, indicating propylene glycol is not only commonly added during food preparation, but also is contained naturally in food.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.1
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• pp.51-55
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• 2008

Although phthalates aren't used as an cosmetic ingredient, some cosmetics especially nail lacquer, hair spray, and perfume still have phthalates. This is mainly caused by contamination and carryover during manufacturing process, so analysis of phthalates in those cosmetics has became a very important thing for quality-assurance(Q.A). The main phthalates under debate are diethyl phthalate(DEP), dibutyl phthalate(DBP), and bis(2-ethylhexyl) phthalate (DEHP) in domestic market. Gas chromatography-mass spectrometry(GC-MS) coupled with solvent extraction and concentration has been used for ppm level and sub ppm level analysis of phthalates. It requires much time and cost to use mass spectrometric detector and to prepare the test solution. Moreover analysis of phthalates at low concentrations is difficult because of contamination which results in wrong analytical results. In the present study, we showed a simple method using gas chromatography-flame ionization detector(GC-FID) which has fast analysis time, minimum use of solvent, reduced sample preparation steps for minimizing contamination and quantitative range of $2{\sim}50{\mu}g/g(ppm)$ in products. Consequently, this method will be proper for Q.A analysis in related companies.

• Fire Science and Engineering
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• v.34 no.3
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• pp.141-149
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• 2020

The Korea Industrial Standards (KS) stipulates methods and test procedures for measuring the horizontal combustibility of cellular plastics exposed to small flames (KS M ISO 9772:2018) and recommendations regarding the magnetic digestion of extruded polystyrene insulation (XPS) for measurement results (KS M 3808:2020). Although products that are certified to conform to KS standards must have burning characteristics (self-extinguishing), they are incinerated and spread by welds at construction sites, causing significant human and property damages. In this study, XPS produced by five companies, certified by KS, and sold in the market were purchased and tested for ignition and diffusion caused by a weld bullion at a construction site. The results showed that the five products had differences in performance. Three out of the five products were found to be self-saturated, but the other two were easily ignited and diffused, making it difficult for them to be self-extinguishing. Based on the result of this experimental investigation in line with the KS regulations, all the three types of products, including two types of products that were incinerated through weld defects, were found to be non-self-extinguishing, as specified in KS M 3808.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.1
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• pp.15-22
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• 2014

This paper presents the implementation of a control system of pellet boiler using wood pellet as carbon neutral material. The system also has the additional features to provide remote controlling and monitoring based on home networking technology through either public switched telephone networks or mobile communication networks. It consists of three kinds of sub-modules; a main controller provides basic and additional features such as a setting of temperature, a supplying of wood pellet, a controlling of ignition and fire-power, and a removing of soot. The second is temperature controller of individual rooms which is connected to the main controller through RS-485 links. And interface modules with PSTN and mobile networks can support remote controlling and monitoring the functions. The test results under the heating area of $172m^2$ show a thermal efficiency of 93.6%, a heating power of 20,640kcal/hr, and a fuel consumption of 5.54kg/hr. These results are superior to those of the conventional pellet boilers. In order to obtain the such high performance, we newly applied a 3-step ignition flow, a flame detection by $C_dS$ sensor, and a fire-power control by fine controlling of shutter to our pellet boiler.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.314-320
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• 2022

The function of reinforcing fibers used in building materials is to maintain resistance to bending loads and to function for cracking caused by drying shrinkage. High-density fiber-cement composites are mainly used for linear plates and are used to increase bending resistance. Therefore, tensile properties, bonding strength with cement hydrate, alkali resistance, and the like are required. Recently, as the non-combustible performance has been strengthened, a function to minimize the occurrence of sparks during high-temperature heating has been added. Therefore, the use of organic fibers is limited. In this study, a study was conducted to replace polypropylene used as reinforcing fiber with hemp fiber with excellent heat resistance. Hemp fibers have excellent heat resistance, good affinity with cement, and excellent alkali resistance. Based on the total volume of polypropylene fibers used in the existing formulation, the non-combustible performance was compared and evaluated by using hemp fibers instead of the polypropylene fibers, and basic physical properties such as flexural strength were tested. As a result of conducting a non-combustibility and physical property test using hemp fibers with a fiber length of 7 mm using 2 % and 3 % by weight, it was found that there is no remaining time of the flame, and the flexural strength can be secured at 95 % level of the existing polypropylene fiber.

• Journal of Korea Foundry Society
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• v.43 no.3
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• pp.107-136
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• 2023

Natural silica sand was commonly used for sand casting of cast steel products, and chromites sand was used to suppress seizure defects due to the lack of thermal properties of silica sand. However there are disadvantages such as deterioration by repeated use, system sand mixing problem, difficulty separating and removing, increased during mold according to high density and to being waste containing chrome. Recently, industrial waste reduction and atmospheric environment improvement have been highlighted as important tasks in the casting industry. In order to solve the problems that occur when using foundry Sand and to improve the environment of casting factories, various artificial sands that can be applied instead of natural silica sand have been developed and introduced. Artificial sands can be classified into artificial sand manufactured by the electric arc atomization or gas flame atomization, artificial sand manufactured by the spray drying & sintering process, artificial sand manufactured by the sintering & crushing process and exhibit different physical properties depending on the type of raw-minerals and manufacturing method. In this study, comparative evaluation tests were conducted on the physical properties of various foundry sands, mold strength, physical durability, thermal durability, and casting test pieces. When comprehensively considering the actual amount of molding sand used according to density, the mold strength according to the shape of sand, the physical and thermal durability of foundry sand, and the heat resistance characteristics of foundry sand, 'Molten artificial sand A1' or 'Molten artificial sand B' is judged to be the most suitable spherical artificial sand for casting of heavy steel castings.

• Journal of Aquaculture
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• v.10 no.3
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• pp.327-334
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• 1997

This study was conducted with Israeli strain of common carp to determine apparent protein, lipid and gross energy digestibility coefficients and apparent calcium and phosphorus availabilities of the following feedstuffs : steam-dried white fish meal (WFM-S), flame-dried white fish meal (WFM-F), brown fish meal (BFM), soybean meal (SBM), corn gluten meal (CGM), sesame meal (SSM), wheat flour (WFL), brewer's yeast (BY) and monocalcium phosphate (MCP). Test diets consisting of a 70:30 mixture of refoernce diet to test ingredient were utilized with chromic oxide as an external indicator. Fecal collection was made during 10 days before the end of feeding trial lasted for 27 days. The best weight gain and feed utilization were found in fish fed MCP containing test diet. Protein digestibility was high for most ingredients, ranging from 81.2% for BY to 91.9% for SBM, with the exception of SSM which was 77.6%. Lipid digestibility coefficients ranged 74% for CGM to 85.8% for two kinds of white fish meal. Digestible energy coefficients were generally high for fish meals, ranging from 77.4% for WFM-S to 81.3% for WFM-F, whereas those for plant feedstuffs were significantly (P<0.05) lower, from 64.5% for CGM to 70.6% for BY. Phosphorus availability from fish meals was variable with a low of 6.6% for WFM-F and a high of 13.6% for WFM-S. Phosphorus availability from SBM and BY was 7.3% and 57.2%, respectively. Calcium and phosphorus availabilities from MCP were 84.6% and 80.6%, respectively. These results provide more precise information concerning nutrients and energy utilization of Israeli strain of common carp and will allow ingredient substitutions in practical diet formulations based on levels of availabile protein and phosphorus.