• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.2
• /
• pp.145-150
• /
• 2005

An extensive numerical analysis is carried out to investigate the slope stability of the wasted mine tailing landfill constructed by the utilization of fine recycled-concrete aggregates. To do this, first, the physical and mechanical properties of the fine recycled-concrete aggregates and the wasted mine tailing are investigated, and the settlement and the change of material properly of the fine recycled-concrete aggregates resulted from reaction with water are also examined. The $OH^-$ elution from the fine recycled-concrete aggregates reacted with water slightly causes the change of material properties such as porosity, permeability and waster absorption, but the settlement does not happen noticeably. The results of numerical analysis of the landfill slope built with wasted mine tailing and recycled-concrete aggregates in alternate layer indicate that slope stability increases with decreasing the slope ratio, with decreasing the groundwater level inside slope, and with increasing the depth of fine recycled-concrete aggregate layer. Based on this study, thus, engineers working in related to the wasted mine tailing landfill design and construction using the fine recycled-concrete aggregates should be considered the slope ratio, the groundwater level, the depth of fine recycled-concrete aggregate layer.

• Korean Journal of Agricultural Science
• /
• v.32 no.1
• /
• pp.19-27
• /
• 2005

This study was performed to evaluate the physical and mechanical properties of polymer concrete using unsaturated polyester resin, initiator, heavy calcium carbonate, crushed gravel, recycled coarse aggregate, silica sand and recycled fine aggregate. The unit weight, compressive strength, flexural strength and dynamic modulus of elasticity were decreased with increasing the content of recycled aggregate. The unit weight, compressive strength, flexural strength and dynamic modulus of elasticity were showed in $2,127{\sim}2,239kg/m^3$, 80.5~88.3MPa, 19.2~21.5MPa and $254{\times}10^2{\sim}288{\times}10^2MPa$ at the curing age 7 days, respectively. Therefore, these recycled aggregate can be used for polymer concrete.

• Journal of the Korean Chemical Society
• /
• v.67 no.6
• /
• pp.420-428
• /
• 2023

Crosslinking was introduced into vinylized-mesoporous silica and recycled polyethylene. By introducing a vinyl group into the mesoporous silica, it becomes a material capable of inducing cross-linking with non-polar polyethylene. By synthesizing vinylized-mesoporous silica and inducing crosslinking with recycled polyethylene, a recycled polyethylene composite with improved physical properties than existing recycled polyethylene was synthesized. In addition, even when a small amount is added according to the grade of recycled polyethylene using vinylized-mesoporous silica, the crosslinking reaction proceeds and all physical properties are improved. Four types of vinylized-mesoporous silica were synthesized, and the shape, microstructure, and functional groups were analyzed by TEM, BET, FT-IR, and XRD. Using vinylized-mesoporous silica, three types of compounds were blended by crosslinking reaction with recycled polyethylene. In order to confirm the presence or absence of crosslinking, analysis was performed using XPS and FT-IR, and physical properties such as tensile strength, elongation, flexural strength, and flexural modulus were confirmed using a universal testing machine. As a result, by applying vinylized-mesoporous silica to recycled polyethylene in various grades, the weak physical properties of existing recycled polyethylene were overcome. By applying the vinylized-mesoporous silica, recycled polyethylene composite material that overcomes the weak physical properties to the normal polyethylene, it shows the optimal physical property index that can be used commercially. Therefore, it is expected that it can potentially increase the use of recycled polyethylene and recycle resources.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.67.2-67.2
• /
• 2010

F doped ZnO (FZO)박막은 rf magnetron sputtering을 이용하여 ZnO 박막에 F의 도핑량 변화에 따른 효과와 전기적, 광학적 및 열적 특성에 대하여 고찰하였다. 열처리 전의 박막에서는 $CF_4$ gas가 0.1%일 때 가장 좋은 전기적 특성을 보였고, 이는 대부분의 F이 O와 치환을 하여 전기적 특성이 우수해지는 것으로 보인다. 그러나 일반적으로 열처리 전 FZO 박막은 낮은 전기적 특성을 가지며, 열처리 후에는 전기적 특성이 많이 향상되었고, 특히 홀 이동도가 $42.6cm^2/Vs$의 높은 값을 가졌다. 또한 F 함량이 증가할수록 광학적 특성은 좋아졌지만, 구조적 특성은 열처리 전 후를 비교할 때 큰 변화가 없었다. 이 연구를 통해서 $40cm^2/Vs$이상의 높은 홀 이동도를 가지고, 열적으로 안정한 ZnO계 박막의 제조가 가능하였다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.3D
• /
• pp.409-418
• /
• 2009

The aim of this study is to analyze the evaluations and determinants on residential resettlements in accordance with urban regeneration by 7,396 samples from 19 housing redevelopment districts in Busan. The major finding on determinants on residential resettlements in accordance with urban regeneration are as follows; A binary logit model for determinants on residential resettlements in accordance with urban regeneration are composed of owner's characteristics, land and building characteristics, housing complex characteristics, and location characteristics. The significant variables in relation to owner's characteristics are owner's age, owner's place of residence, the possession period against property and investment intention. As a result of logit model for residential resettlements, it shows that the variables in relation to land and building characteristics are the land classification, the use of building, the size of land or building, the permission of building and the appraisal price on land and building. This result means that actual customer's investment connects to resettlement after redevelopment project. The other side, the housing complex variables consist of the brand of construction company, the ratio of large size housing and floor are ratio shows that improvable conditions for housing value are important factor to induce residence's resettlement. The location variables show that Dongbusan has higher probability, the reverse Jungbusan has lower probability in residential resettlement likewise residential preference.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.8
• /
• pp.5195-5200
• /
• 2014

White LEDs are expected to be applied widely as a lighting system. To make white LED chips, one requires a mixture with silicon and a phosphor coating on a LED blue chip. The process of preparing a mixture with silicon using phosphor involves the use of discarded phosphor in the chip process. Reducing the costs of chip production depends on many factors, such as the mixture errors, exposure over time of silicon, and changes in the characteristics of blue chip. This paper reports the characteristics of a white LED chip manufactured through a reproduction process of derelict phosphor. This method was applicable to a real LED flashlight. A derelict phosphor chip showed similar results to a normal white chip for the degradation of cd 3.2[Cd] and 3.6[Cd], color temperature, 57[K] and 58[K], and maximum white wavelength 444.3[nm] and 449.8[nm]. These results are expected to make ea great contribution to cost reduction.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.05a
• /
• pp.133-137
• /
• 2008

Results of combustion tests performed for a regenerative cooling combustor of a 30 tonf-class liquid rocket engine were described. The combustion chamber has chamber pressure of 60 bar, propellant mass flow rate of 89 kg/s, and nozzle expansion of 12. The combustion chamber is composed of mixing head, baffle injector, and regenerative cooling chamber. The hot firing tests were performed at design and off-design points. The test results show that the combustion characteristic velocity is in the range of 1738${\sim}$1751 m/sec and the specific impulse of the combustion chamber is in the range of 253${\sim}$270 sec. The peak of combustion characteristic velocity and specific impulse for this combustor is shown at mixture ratio of 2.35 and 2.5, respectively.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.11a
• /
• pp.57.1-57.1
• /
• 2010

ITO(Indium Tin Oxide)는 전도도와 투과도 특성이 뛰어나 디스플레이, 태양전지, LED 등 여러 산업에서 전극 물질로 널리 사용 되어져 왔다. 최근 ITO의 사용이 급격히 증가하면서 이에 대한 연구가 활발히 진행되고 있다. ITO는 막의 특성을 좋게 하기 위하여 증착 시 Ar gas와 함께 $O_2$가스를 첨가하기도 한다. 본 연구에서는 산소 분압에 따른 ITO 박막의 전기적, 광학적 특성에 대하여 연구하였다. Corning사의 eagle 2000 glass 기판위에 스퍼터링을 이용하여 ITO layer를 증측하였고, 증착시, $O_2$ partial pressure를 0 - 0.5%까지 0.1% 간격으로 가변하였다. 증착된 샘플은 Sinton사의 UV-vis 장비를 이용하여 광학적 특성을 측정하였고, Hall measurement 장비를 이용하여 전기적 특성을 측정하였다. ITO 박막은 $O_2$의 partial pressure가 증가할수록 향상된 전기적, 광학적 특성을 나타내었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.05a
• /
• pp.54-60
• /
• 2010

액체로켓엔진 시스템의 시동 및 정지 또는 추력 제어와 같은 천이 작동시 동특성을 예측하기 위한 선행 연구로서 추진제 공급 시스템의 구성품에 대한 동특성 모델링을 수행하였다. 연료 공급계통과 산화제 공급 계통의 구성품들은 재생냉각채널을 제외하고 같은 것으로 가정하였다. 동특성 모델링의 대상 구성품은 펌프, 관로, 오리피스, 제어 벨브, 재생냉각채널, 인젝터 등이며 실제 엔진 시스템의 축소모형에 대한 수력시험을 통해 각 구성품의 동특성 모델링을 검증하였다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2010.04a
• /
• pp.538-541
• /
• 2010

본 연구에서는 현재 시중에 판매되고 있는 네 가지 휴대용 음원재생기를 자극물로 사용하여 제품 속성에 있어서의 차이가 사용자 경험의 여러 요소에 영향을 주는지 여부(가설 1)와 사용자의 정서적 반응이 사용자가 인식한 제품 특성에 의해 영향을 받는지(가설 2) 그리고 제품에 대한 전체적인 판단이 사용자가 인식한 제품 특성과 감성적 반응에 따라 달라지는지(가설 3) 실험을 통해 조사하였다. 실험결과 기능적 특성과 유희적 특성에 대한 인식 정도는 실험 참가자가 사용한 제품에 따라 서로 다르게 나타났으며, 사용자의 정서적 반응과 전체적인 선호도 또한 평가 제품에 따라 서로 다르게 나타남으로서 제품 속성에 의해 영향을 받는 것으로 분석되었다. 이와 함께 사용자 경험을 구성하는 요소들 간의 상호관계도 테스트하였는데, 사용자의 정서적 반응이 주로 제품의 기능적 특성에 따라 달라지는 반면 사용자의 전체적인 판단은 제품의 기능적 특성과 유희적 특성 모두에 의해 영향을 받고 있는 것으로 나타났다. 또 분석결과에서 밝혀진 한 가지 흥미로운 사실은 사용자의 정서적 반응이 전체적인 판단에 아무런 역할도 하지 않는다는 점이다.