• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.34-39
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• 2015

The feasibility of recycling wasted printed circuit board (PCB) is investigated by preparing PCB added flame retardant composites filled with either unsaturated polyester or polyurethane. In order to improve electroconductive properties, copper powder was added into the composites, which results also in improving their antistatic properties. The prepared composite samples showed a binding between the polymer fillers observed by a scanning microscope. The sample group using unsaturated polyester is elastomeric that led to appreciable elongation and elasticity. In case of polyurethane, the tensile strength increased proportionally as increase of the amount of PCB powder. The composite materials can be utilized as antistatic composite materials, since the surface resistivity result showed increase of the electroconductive properties by adding Cu. The flammability of the samples is not satisfactory according to UL-94 vertical test. However, the flame retardant properties were improved by adding PCB power. This study, therefore, showed that it is feasible to fabricate polymer composite materials and improve the material characteristics by adding PCB powder, which can replace existing additives used for the preparation of polymer composite materials and can reduce the environment contamination by recycling the wasted PCB.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.45-52
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• 2010

The purpose of this study is application to flame retardant powder coating(FRPC) material consisting of ammonium polyphosphate(APP) and magnesium hydroxide($Mg(OH)_2$) as a halogen free flame retardant into thermoplastic resin(LDPE-g-MAH). For improvement of adhesion, LDPE-g-MAH was synthesized from low density polyethylene(LDPE) and maleic anhydride(MAH). The mechanical properties as melt flow index, pencil hardness, cross-hatch adhesion and impact resistance of FRPC were measured. Also, the limited oxygen index(LOI) values were measured 17.3vol%, 31.1vol% and 33.7vol% for LDPE-g-MAH, FRPC-3(APP 15wt%, $Mg(OH)_2$ 15wt%) and FRPC-5(APP 30 wt%), respectively. The thermo gravimetry/differential thermal analysis(TG/DTA) of FPRC-3 was observed endothermic peak at $340^{\circ}C$ and $450^{\circ}C$, it was confirmed predominant thermal stability though the wide temperature range by APP and $Mg(OH)_2$. It was showed V-0 grade for FRPC-3 and FRPC-4(APP 20wt%, $Mg(OH)_2$ 10wt%) that a char formation and drip suppressing effect, and combustion time reduced by UL94(vertical burning test). It was confirmed that flame retardancy was improved with the synergy effect because of char formation by APP and $Mg(OH)_2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.212-212
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• 2008

에폭시 수지는 화학적 열적 안정성과 절기 절연성 및 기계적 특성 등 여러 가지 우수한 특성에도 불구하고 난연성은 그 단독으로 만족시킬 수 없기 때문에 난연제를 첨가함으로써 난연효과를 얻어왔다. 기존에 할로겐 화합물인 브롬계 난연제는 우수한 난연효과에도 불구하고 연소시 유해물질이 발생되어진다. 그리하여 인계 난연제를 첨가하는 것이 고분자 시스템에 난연성을 부여하는 효과적인 수단으로 대두되어지고 있다. 이 실험에서는 인계 난연제와 브롬계 난연제를 10, 20, 30, 40wt% 첨가하여 epoxy composite 제작하였다. 제작된 epoxy composite를 UL-94V 방법으로 난연성 평가하여 브롬계 난연제 20wt%에서 V-0를 획득할 수 있었으나 인계난연제 40wt%에서도 V-0를 만족할 수 없었다. 난연제 함량에 따른 Dielelctric constant 및 loss는 브롬계 난연제를 첨가시 감소하였고, 인계난연제의 경우 증가하였다.

• Culinary science and hospitality research
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• v.14 no.1
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• pp.94-106
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• 2008

This study is conducted to explore the cooks' recognition of culinary environment of school feeding among the cooks working for elementary schools, middle schools, and high schools in the Ulsan district. A total of 200 samples were distributed and 185 samples were collected; among them, 182 valid samples were selected for research. Answers were processed by SPSS 12.0. after data coding. As for factor analysis of culinary environment, three factors were extracted, which are general environment, human environment, and facilities equipment environment. It was found that general environment included ventilation(31.5%), temperature (29.0%), humidity(22.1%) in the order of importance; human environment covered cooperation among cooks (28.1%), the number of cooks(25.7%), and professionalism of cooks in the order of importance; facility equipment environment contained the design and layout of facilities and equipment(29.3%), various safety facilities, and safety device(23.3%) in the order of importance. However, a measure for improving work environment, number of cooks, deterioration of equipment, etc. should be considered.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.5
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• pp.89-94
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• 2013

The fire testing performed for smoke detector model approval in Korea tests only one kind of fire smoke. A photoelectric spot-type smoke detector using Mie scattering is affected by the wavelength of light beam and the particle diameter. According to UL (Underwriters Laboratories Inc.) 268 standard, this paper analyze the characteristic of the response for a photoelectric spot-type smoke detector on sale in Korea using various fire smokes. Probability that the response time is included in non-defective range is 100% in paper fire, 90% in wood fire and 75% in flammable liquid fire, 90% in wood fire and 75% in flammable liquid fire. According to the estimation for population mean of the response time choosing a confidence level of 99%, a maximum of 19% for wood fire and that of 38% for flammable liquid fire are defective. As the result of analysis of smoke particle, this paper is found that these results are caused by the smoke particles are wide variations in size or have very black.

• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.283-292
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• 2006

So that high-strength and electrical properties apply by excellent high voltage insulator electricity material, ATH content and platinum-based flame retardant that influence in flame retardant and tracking characteristic among composite of silicone rubber studied mechanical strength and influence getting to electrical properties. Composition of ${\alpha}$, ${\omega}-vinyl$ poly (dimethyl-methylphenyl) siloxane(VPMPS) of a polymer quantity made doing mole of D4, $D3^{Me,Ph}$ and VMS by 1000:15:0.2 mole ratio and uses basic catalyst tetramethylammonium silanolate(TMAS) and do opening equilibrium polymerization to be used to main polymer for high voltage insulation insulator. Control ATH content and content of platinum-based flame retardant and made high voltage insulation silicone rubber. Measured mechanical strength of making silicone rubber using UTM, and tracking characteristic according to standard of IEC 60587, flame retardant test studied effect that flame retardant characteristic gets in tracking characteristic, measuring according to UL94V method of test.

• Advances in materials Research
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• v.4 no.2
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• pp.97-111
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• 2015

Polypropylene short fiber (PP)-clay particulate-epoxy ternary composites were prepared by reinforcing PP short fiber and clay particles in the range of 0.1 phr to 0.7 phr into epoxy resin. Prepared hybrid composites were characterized for their mechanical, thermal and flame retardant properties. The obtained results indicated an increase in impact resistance, tensile strength, flexural strength and Young's modulus to an extent (up to 0.5 phr clay and 0.5 phr PP short fiber) and then decreases as the reinforcing phases are further increased. The thermal stability of these materials are found to increase up to 0.2 phr clay and 0.2 phr PP addition, beyond which it is decreased. Addition of clay is found to have the negative effect on epoxy-PP short fiber composites, which is evident from the comparison of mechanical and thermal properties of epoxy-0.5 phr PP short fiber composite and epoxy-0.5 phr PP short fiber-0.5 phr clay composite hybrid. UL-94 tests conducted on the composite hybrids have showed a reduction in the burning rate. Morphological observations indicated a greater fiber pull with the addition of clay. The performed tests in the present study indicated that materials under investigation have promising applications in construction, agriculture and decorative purposes.

• Journal of the Korean Society of Safety
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• v.13 no.3
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• pp.102-111
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• 1998

This study was concerned with the development of a heavy duty rust-converting agent, the function of which is to form metal complex coatings, containing vinyl halide-acrylic terpolymer emulsion, defoamer, emulsifying agent, glass flakes, chelating agent such as gallotannic acid, gallic acid, and pyrogallic acid, and other additives. The resulted emulsion products(Sample No.1~No.5) were characterized through test either in the forms of emulsions, which include Viscosity, Penetration rate, Acidity and Film drying rate test, or in the forms of coated layer on rusty steel substrates by FT-IR, which include hardness, gloss, salt spray, adhesion and flame retardant test. The test results are as follows ; Penetration rate(0.1~0.4 mm/min), Solid content(70%), Acidity (pH 1.8~2.0), Specific gravity(1.30~1.35), Film drying rate(108min, RH 40% ; 150min, RH 80%), Gloss(83~92, incident angle $60^{\circ}$; 88~97, incident angle $85^{\circ}$), Pencil hardness(4H~5H), Adhesion (100/100), Salt spray test(>720Hr), LOI(%) value(38%), Vertical burning test(UL 94-v-l). According to the various performance of specimens show above, the evaluation of the availability of this heavy duty rust-converting agent can be concluded that all the samples(No.1~No.5) are capable of being used in the field of chemical plant and in the hazard areas of fire and explosion potential. It was observed that the properties of sample No.2, especially gloss and hardness, were much better than that of the other samples.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.4
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• pp.349-355
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• 2019

A fire, be it caused intentionally or unintentionally, leads to economic loss and physical damage, and requires digestion. The number of fires is increasing yearly, and electrical fires account for more than 30% among the main causes of fires. Electric wires that catch fire typically employ silicone coatings; silicone has organic as well as inorganic properties. Silicon is a natural, nonexistent, synthetic product with numerous applications. In this study, a silicon rubber for application in wires was prepared by high-temperature vulcanization (HTV) with a Shore A hardness of 70. We report results for the flame retardancy test and the fire safety characteristics via inorganic analysis. For this, a quartz inorganic material was added to the wire specimen, and 18% powdered extinguishing agent ammonium phosphate and expanded vermiculite respectively. Thus, expanded vermiculite showed the best flame retardancy and fire safety characteristics.

• Journal of Ceramic Processing Research
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• v.20 no.4
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• pp.411-417
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• 2019

Graphene doped zinc oxide nanoparticles (G-ZnO) were prepared using modified hummer's technique together with the ultrasonic method and characterized by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), fourier-transform infrared spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM). Different samples of epoxy resin nanocomposites reinforced with G-ZnO nanoparticles were prepared and were marked as F1 (without adding nanoparticles), F2 (1% w/w G-ZnO), and F3 (2% w/w G-ZnO) in combination of ≈ 56:18:18:8w/w% with epoxy resin/hardener, ammonium polyphosphate, boric acid, and Chitosan. The peak heat release rate (PHRR) of the epoxy nanocomposites was observed to decrease dramatically with the increasing G-ZnO nanoparticles. However, the LOI values increased significantly with the increase in wt % of G-ZnO nanoparticles. From the UL-94V data, it was confirmed that the F2 and F3 samples passed the flame test and were rated as V-0. The results obtained in the present work clearly revealed that the synthesized samples can be used as efficient materials in fire-retardant coating technology.