• Journal of the Korean Applied Science and Technology
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• v.18 no.1
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• pp.40-48
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• 2001

Curing reaction was carried out with the acrylic resin (ACR) [n-butyl acrylate/atyrene/2-hydroxyethyl methacrylate/acetoacetoxyethyl methacrylate (AAEM)] synthesized before and a curing agent, hexamethoxymethylmelamine (HMMM). With rotational rheometer, the effect of catalysts on curing rate of acrylic resin/melamine was examined. Among the four catalysts used, p-toluene sulfonic acid showed the highest reactivity, and the optimum amount of catalyst was 0.5 phr. It was observed that in the ACR/HMMM curing reaction, gelation point was lowered with the increasing the amount of AAEM and HMMM in the ACR.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1718-1721
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• 2015

본 논문에서 구현한 헬스케어 서버 시스템은 사용자가 스스로 자신의 건강을 관리할 수 있도록 돕는 플랫폼으로서, 모바일 애플리케이션을 이용하여 자신의 운동, 식단 등과 같은 건강기록을 관리할 수 있으며, 또한 건강기록들을 바탕으로 사용자에게 알맞은 건강 정보를 제공한다. 또한 개인 건강기록(PHR) 정보와 라이브로그를 저장하기 위한 데이터베이스 및 지식베이스를 설계하고, 온톨로지 및 데이터마이닝 기법을 적용하여 사용자에게 맞춤형 건강정보를 제공하는 기능을 수행한다.

• Elastomers and Composites
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• v.5 no.1
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• pp.69-74
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• 1970

The influence of various calcium carbonate on the physical properties of natural rubber have teen carries out extensive experiments on compounding. Final evaluation was made through various kinds of physical test-tensile strength, modulus, tear strength and hardnees-including particle size. The results are as follows: 1. Generally, tile tensile strength, modulus and tear strength showed the similar tendency in various calcium carbonate compounding. 2. The maximum volume of general using have been obtained with 150 phr calcium carbonate in $NR-CaCO_3$ compounding. 3. The particle size of domestic calcium carbonate showed $1.0\mu-2.6\mu$.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.2_1
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• pp.79-89
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• 2021

Poly(lactic acid) (PLA) is considered as one of the most promising bio-based polymers due to its high strength, high modulus, good processability, transparency after processing, and commercial availability. This study aimed to investigate the mechanical, thermal, and migration properties of poly(lactic acid)/zeolite (10 phr) composites prepared with various biocompatible plasticizers, such as triethyl citrate(TEC), tributyl citrate(TBC), and poly(ethylene glycol)(PEG400), through differential scanning calorimetry(DSC), thermo-gravimetric analysis(TGA) and standard tensile testing. The incorporation of PEG400 significantly increased the elongation at break, and DSC results showed that the addition of plasticizers drastically decreased the T_g of PLA/zeolite composites and improved the melt flow and processability. Besides, it was found from TGA results that PLA/zeolites composites plasticized by TEC and TBC were more easily to be thermally degraded than the composites plasticized by PEG400.

• Bulletin of the Korean Chemical Society
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• v.19 no.2
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• pp.174-178
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• 1998

Blowout of NR and SBR vulcanizates was studied using a microwave oven. Rubber vulcanizates with different contents of carbon black (0, 30, 50, 70 phr) and various cure systems (conventional, semi-EV, and EV) were prepared. Unfilled rubber vulcanizates did not exploded by irradiation of microwave, while carbon black-filled ones exploded within 10 min. A blowout time of the carbon black-filled rubber vulcanizate decreases with an increase of the content of carbon black in the vulcanizate. A blowout temperature of the organic additive-extracted vulcanizate is higher than that of the not-extracted one, but the extracted vulcanizate blows out faster than the not-extracted one. A blowout temperature of the overcured vulcanizate is higher than that of the undercured one with the same cure system. Temperatures of unfilled SBR vulcanizates heated by the microwave irradiation are lower than those of unfilled NR ones. The carbon black-filled SBR vulcanizates blow out at higher temperatures than the carbon black-filled NR ones. Blowout times of the carbon black-filled SBR vulcanizates are longer than those of the carbon black-filled NR ones.

• Journal of Korea Multimedia Society
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• v.23 no.12
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• pp.1496-1506
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• 2020

With the progress of miniaturization and high performance of various sensors, a lot of data is generated in various fields and being collected in real-time, but the use of such large-capacity data is often unable to keep up with the collection technology. In the medical field, health data is collected and managed by platform, which causes inconvenience to users in searching their own health data and receiving medical services. In this paper, in order to solve these problems, we designed and implemented PHDItemReader to improve the speed of data query in a batch application environment that can integrate and process health data having various data expression formats. The experiment compared and analyzed 3 types of query speed based on 1,000,000 hypothetical health data, and as a result of the experiment, it was verified that the PHDItemReader implemented in this paper improved up to about 21% compared to the existing one.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.139-140
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• 2024

최근 중대재해처벌법 등 근로자의 안전 및 건강관리를 위한 인식이 확산되며, 기업들의 근로자 건강관리 솔루션으로 디지털헬스케어의 건강관리서비스 플랫폼이 주목받고 있다. 그러나 국내 디지털헬스케어 시장에서 건강관리서비스 플랫폼은 사업화 단계에서 어려움을 겪고 있다. 본 논문에서는 개인건강기록에 기반한 맞춤형 건강관리서비스 플랫폼의 성공요인의 우선순위를 도출하여 효과적인 운영을 위한 실질적 전략의 시사점을 제시하였다. AHP 방법론을 통한 플랫폼 공급자와 수요자 측면 전문가 집단 연구 결과 법/제도, 데이터 분석 및 플랫폼 설계, 시스템 보안성, 시스템 안정성순으로 나타났다, 본 연구의 우선순위 결과를 통해 건강관리서비스 플랫폼, 나아가 국내 디지털헬스케어의 활성화 및 경쟁력 제고에 기여할 수 있기를 기대한다.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.251-258
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• 2015

In the study, PLLA with 12,000 g/mol ($M_n$) and 14,000 g/mol ($M_w$) was synthesized from L-lactide, and used to synthesize PLLA-Br intermediate. PLLA-block-PMMA with 84,000 g/mol ($M_n$) and 126,000 g/mol ($M_w$) was finally synthesized from PLLA-Br intermediate. The glass transition temperature ($T_g$) and initial pyrolysis temperature of PLLA-block-PMMA are $95.5^{\circ}C$ and $289^{\circ}C$, respectively. The PLA film of $50{\pm}3{\mu}m$ thickness was prepared by blending PLA with 9 phr PLLA-block-PMMA followed by stretching biaxially at 3 times under $95^{\circ}C$, and annealing at $120^{\circ}C$ for 2 min. The light transmittance at 550 nm and tensile strength of the film are 88.5% and 44.5 MPa, respectively. To enhance the tensile strength of PLA film, it was required to keep the film more than 2 min at $120^{\circ}C$ during the annealing step after a biaxially orientation.

• Polymer(Korea)
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• v.39 no.3
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• pp.433-440
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• 2015

Aluminum trihydroxide (ATH) has been commonly employed as a flame retardant for ethylene vinyl acetate (EVA) copolymers. In the present work, ATH was obtained from a recycling process of multi-layer packaging film wastes. EVA/ATH composite samples were prepared using a two roll-mill and flame retardancy of EVA/ATH composites were examined using limiting oxygen index (LOI) and flame retardancy test (UL94). We observed excellent flame retardancy in case of adding 150 phr or more of recycled ATH to EVA. Particle size and specific surface area play crucial roles in LOI value and UL-94 classification of the EVA/ATH composites. Smaller particle size and higher specific surface area of ATH was found out to improve the flame retardancy. Regarding tensile properties, crosslinked EVA/ATH compounds which is practically used for electric cables had similar to or even better tensile property values than the ones without ATH.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.53-58
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• 2015

Polycarbonate (PC)/graphene oxide (GO) composites with 3 phr of GO were prepared by using a twin screw extruder at 240, 260, and $280^{\circ}C$ after mixing the solution with chloroform. It was confirmed by DSC and TGA that the glass transition temperature ($T_g$) of PC/GO composites were not changed and the thermal stability was the best in case of the extrusion temperature at $260^{\circ}C$. Thermo mechanical properties of PC/GO composites according to extrusion temperatures were measured by dynamic mechanical analysis (DMA). Storage moduli of PC/GO composites were higher than that of pure PC and there was no detectable changes at varying the extrusion temperature. Based on these results, the extrusion temperature of PC/GO composites was fixed at $260^{\circ}C$. The degree of the chemical reaction of PC/GO composites with respect to the GO reduction time was confirmed by the C-H stretching peak at $3000cm^{-1}$ and the degree of the chemical reaction was similar to that of GO when the reduction time was 1 h. A decrease in the complex viscosity as a function of the GO reduction time was detected by dynamic rheometer, which may be originated from the enhancement of GO dispersion by PC-GO reaction. The GO dispersion was confirmed by scanning electron microscope (SEM).