• Journal of Ceramic Processing Research
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• 제20권4호
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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.

• 한국염색가공학회지
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• 제34권4호
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• pp.234-240
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• 2022

Use of processed timber can help reduce environmental damage and the economic burden of resources (important problems with use of raw timber) and can meet the needs of various fields where the sensibility of raw timber is required. Veneer wood is positioned as a high-value-added product due to its luxury and beauty, and it is used in various fields as a building-related material, such as interior decoration, furniture, flooring, building interior materials, and lumber. Dyeing is necessary to enhance the aesthetic appearance of this pattern and to expand its use. Therefore, in this study, we compared and analyzed the dye ability of oak-patterned materials with reactive dyes, and evaluated their performance as interior materials. As a result, the oak pattern was dyed with 9 kinds of reactive dyes and a comparative analysis was performed. The most suitable conditions are 50℃, 2 hours, and 0.5% o.w.f. In addition, evaluating resilience to daylight, resilience to rubbing, fire resistance, and flame retardance, yielded results suitable for use as an interior material. In this study, the dyeability of veneer dyed under various conditions using reactive dyes was compared and analyzed the performance as an interior material was evaluated.

• 해양환경안전학회지
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• 제27권2호
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• pp.377-386
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• 2021

A60 급 갑판 관통 관은 선박과 해양플랜트에서 화재사고가 발생할 경우 화염의 확산을 방지하고 인명을 보호하기 위해 수평구조에 설치되는 방화장치이다. 본 연구에서는 다양한 대리모델과 다중 섬 유전자 알고리즘을 이용하여 A60 급 갑판 관통 관의 방화설계에 대한 이산변수 근사최적화를 수행하였다. A60 급 갑판 관통 관의 방화설계는 과도 열전달해석을 통해 평가하였다. 근사최적화에서 관통관의 길이, 지름, 재질, 그리고 단열재의 밀도는 이산설계변수로 적용하였고, 제한조건은 온도, 생산성 및 가격을 고려하였다. 대리모델 기반의 근사최적설계 문제는 제한조건을 만족하면서 A60 급 갑판 관통 관의 중량을 최소화할 수 있는 이산설계변수를 결정하도록 정식화하였다. 반응표면모델, 크리깅, 그리고 방사기저함수 신경망과 같은 다양한 대리모델이 근사최적화에 사용되었다. 근사최적화의 정확도를 검토하기 위해 최적해의 결과는 실제 계산 결과와 비교하였다. 근사최적화에 사용된 대리모델 중 방사기저함수 신경망 모델이 A60 급 갑판 관통 관의 방화설계에 대해 가장 정확한 최적설계 결과를 나타내었다.

• 한국도로학회논문집
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• 제17권4호
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• pp.53-61
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• 2015

PURPOSES : The objective of this study is to evaluate the SDAR (solvent deasphaltene residue), which is obtained from the solvent deasphalting (SDA) process, as a pavement material. METHODS : The physical properties of the SDAR were evaluated based on its chemical composition, and asphalt mixtures with the SDAR were fabricated and used for the evaluation of mechanical properties. Firstly, the chemical composition of SARA (saturate, aromatic, resin and asphaltene) was analyzed using the TLC-FID (thin-layer chromatography-flame ionization detector). Moreover, the basic material properties of the asphalt binder with the SDAR were evaluated by the penetration test, softening point test, ductility test, and PG (performance grade) grade test. The rheological properties of the asphalt binder with the SDAR were evaluated by the dynamic shear modulus ($G^*$) obtained using the time-temperature superposition (TTS) principle. Secondly, the mechanical properties of the asphalt mixtures with the SDAR were evaluated. The compactibility was evaluated using the gyratory compacter. Moreover, the tensile strength ratio (TSR) was used for evaluating the moisture susceptibility of the asphalt mixtures (i.e., susceptibility to pothole damage). The dynamic modulus $E^*$, which is a fundamental property of the asphalt mixture, obtained at different temperatures and loading cycles, was used to evaluate the mechanical properties of the asphalt mixtures. RESULTS AND CONCLUSION : The SDAR shows stiffer and more brittle behavior than the conventional asphalt binder. As the application of the SDAR directly in the field may cause early failures, such as cracks on pavements, it should be applied with modifiers that can favorably modify the brittleness property of the SDAR. Therefore, if appropriate additives are applied on the SDAR, it can be used as a pavement material because of its low cost and strong resistance to rutting.

• 한국화재소방학회논문지
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• 제23권2호
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• pp.111-116
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• 2009

시중에 유통되는 17종의 방염 도료를 소방법에서 요구하는 성능에 맞게 MDF에 방염처리하여 화재시 발생되는 복사열에 노출시켰을 경우 어느 정도의 화재지연 효과가 있는지를 연구하였다. 복사열의 크기는 콘히터를 이용하여 $10kW/m^2$에서 $30kW/m^2$까지 변화시키며 실험하였다. 착화시간과 착화형태를 측정하였으며 시료 표면의 온도를 측정하였다. 실험 결과 방염도료를 처리한 시료의 착화 임계열유속은 $10kW/m^2$ 였으며 $30kW/m^2$에서는 방염에 의한 착화지연효과가 없음을 확인할 수 있었다. 또한 시료 표면온도가 $400^{\circ}C$ 이상이 되어도 방염에 의한 화재 억재효과를 기대하기 어렵게 됨을 알 수 있었다.

• 한국추진공학회지
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• 제23권6호
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• pp.21-27
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• 2019

우주 항공용 노즐에 사용되는 셀룰로오스계 탄소 직물은 낮은 열전도도, 높은 내삭마 특성을 가지고 있다. 그러나 내염화 및 흑연화 공정에서 70~90% 중량이 감소하여 최종 탄소 직물 제조 시 수율이 낮은 단점이 있다. 본 연구에서는 리오셀 직물에 인계난연제로 인산(Phosphoric acid), 가교제로 시트르산(Citric acid)을 사용하여 전처리한 후 FT-IR, XRD, TGA 분석을 통하여 화학적 구조 및 열적 특성 변화를 확인하였다. 또한 리오셀 직물의 내염화 및 흑연화 후 중량을 측정하여 시트르산이리오셀 직물 수율 변화에 미치는 영향에 대하여 확인하였으며, 16 wt% 첨가 시 흑연화 수율이 8.1% 까지 증가하는 것을 확인하였다.

• 대한가정학회지
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• 제27권4호
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• pp.167-191
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• 1989

The present study was conducted to devlop and appropriate retirement home model for the elderly in terms of clothing and textiles; nutrition, health, and foodservice; housing and environment; and psychological adaptation. Specifically, the purposes of the study were: 1) to provide basic guidelines for clothing by comparing the clothing behavior of the elderly living in the retirement home and those living in their own homes with family, 2) to provide basic guidelines for balanced diet and effective foodservice, 3) to develop an ideal life space and facilities, and 4) to assess the psychological characteristics of the elderly. Questionnaires, observation, experimental method, and survey of literature were used for the study. Clothing behavior showed that the elderly were much concerned about clothing, and they preferred comfortable as well as fashionable designs. The elderly in the retirement homes complained of a lack of quantity and variety in clothing. They preferred natural fiber rather than blended fabrics. Flame resistance, thermal insulation, and flexibility of textile fabrics were found to be prime considerations in manufacturing and selecting clothing materials for the elderly. The health status of the surveyed elderly was generally good, but some poor eating habits were observed. Dietary nutrients intakes were generally sufficient, but several nutrients intakes were insufficient. The level of equipment in the kitchens of the institutions was low. Furthermore, the employment rate of dietitians in institutional settings was extremely low. This resulted in a lack of systematic foodservice management. Residents in the institution were generally satisfied with present life space and facilities but this was mainly because of abandonment, adaptation, and past experience. Optimal allocation of residents per bedroom and an adequate design for storage, bathroom, utility room, and dining room were recommended. The comparison of psychological status of the elderly living at home was more stable than those living in an institution. The emotional state of the elderly living in the institution was characterized by loneliness; they did not have close interpersonal relationships or future plans. An appropriate model for the elderly was developed on the basis of these findings.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.378-385
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• 2016

전기 분 배전반의 내부 회로 인 부스 바는 충전부의 노출로 인해 전기 사고의 원인이 되며 이로 인한 감전 사고와 단락 사고가 발생된다. 또한 동물 및 이물질 침투로 인한 전기 화재 사고가 발생되는 원인이 되기도 한다. 또한 확장이 불가능한 구조로 무리하게 연결하여 사용하므로 접촉 저항 증가 발생으로 과열 사고를 유발시키기도 하며, 절단과 절곡 등의 제조 공정상의 어려움을 가지고 있기 때문에 주문생산방식을 택할 수밖에 없는 현실이며, 긴급전기 사고 발생시 복구하는데 지연되는 원인이 되기도 한다. 본 논문에서는 이와 같은 문제점을 개선하기 위해서 분 배전반의 모선을 절단하여 개별 블록으로 절연 난연 케이스와 격벽 구조화로 안전성을 높여 모듈 블록화 하였으며, 확장성과 유연성을 구현하였으며, 쉽게 확장이 가능한 구조이며, 또한 쉽게 분 배전반을 조립할 수 있다는 것이며, 이와 같이 전기적 위험 요소를 제거한 전기 분 배전반의 내부 구조는 블록형 부스 바 구조를 가지고 메인차단기와 분기차단기간의 회로 형성 구현 방식의 분 배전반를 제안하고 공인시험기관의 시험을 통해 그 유용성을 입증 하였다.

• Composites Research
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• 제33권3호
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• pp.91-100
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• 2020

폴리페닐렌설파이드(PPS)는 반결정성 엔지니어링 열가소성 수지로 뛰어난 열안정성, 우수한 기계적 강도, 고유의 난연성 및 내화학성, 전기적 특성을 갖고 있다. 이러한 우수한 특성으로 인해 PPS는 복합체의 매트릭스로 선호되고 있다. PPS의 기계적 물성을 향상시키며 기능성 부여를 위해 탄소섬유나 유리섬유와 같은 필러를 이용한 복합화 연구가 진행되어 오고 있다. 본 총설 논문에서는 PPS와 탄소나노튜브, 그래핀, 탄소섬유, 유리섬유 등과의 복합체 제조 및 응용에 대한 연구를 소개하고자 한다.

• 대한금속재료학회지
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• 제50권1호
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• pp.71-77
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• 2012

We studied the effect of heat treatment on the microstructures and mechanical strength of the solder joints in the Light Emitting Diode (LED) packages. The commercial LED packages were mounted on the a flame resistance-4 (FR4) Printed Circuit Board (PCB) in the reflow process, and then the joints were aged at $125^{\circ}C$ for 100, 200, 300, 500 and 1000 hours, respectively. After the heat treatment, we measured the shear strength of the solder joints between the PCB and the LED packages to evaluate their mechanical property. We used Pb-free Sn-3.0Ag-0.5Cu solder to bond between the LED packages and the PCBs using two different surface finishes, Electroless Nickel-Immersion Gold (ENIG) and Electroless Nickel-Electroless Palladium-Immersion Gold (ENEPIG). The microstructure of the solder joints was observed by a scanning electron microscope (SEM). (Cu,Ni)6Sn5 intermetallic compounds (IMCs) formed between the solder and the PCB, and the thickness of the IMCs was increased with increasing aging time. The shear strength for the ENIG finished LED package increased until aging for 300 h and then decreased with increasing aging time. On the other hand, in the case of an ENEPIG finished LED package, the shear strength decreased after aging for 500 h.