• Geomechanics and Engineering
• /
• 제13권1호
• /
• pp.25-41
• /
• 2017

In recent years, the amount of sludge ash (SA) has considerably increased due to rapid urbanization and population growth. In addition, its storage in landfills induces environmental pollution and health problems. Therefore, its disposal in an environmentally friendly way has become more important. The main goal of this study is to investigate the reusability of sludge ash as an additive with polypropylene fiber (PF) to stabilize marginal sand based on the compressive strength performances from UCS tests. For this purpose, a series of UCS tests was conducted. Throughout the experimental study, the used inclusion rates were 10, 15, 20 and 30% for sludge ash and 0, 0.5 and 1% for polypropylene fiber by total dry weight of the sand+sludge ash mixture and the prepared samples were cured for 7 and 14 days prior to the testing. Freezing and thawing resistance of the mixture including 10% sludge ash and 0, 0.5 and 1% polypropylene fiber was also examined. On the basis of UCS testing results, it is said that sludge ash inclusion remarkably enhances UCS performance of sand. Moreover, the addition of polypropylene fiber to the admixtures including sand and sludge ash significantly improves their stress-strain characteristics and post-peak strength loss as well as UCS. As a result of this paper, it is suggested that sludge ash be successfully reused with polypropylene fiber for stabilizing sand in soil stabilization applications. It is also believed that the findings of this study will contribute to some environmental concerns such as the disposal problem of sludge ash, recycling, sustainability, environmental pollution, etc. as well as the cost of an engineering project.

• 한국산학기술학회논문지
• /
• 제16권7호
• /
• pp.4969-4976
• /
• 2015

우리나라는 국토의 약 2/3이상이 산악지형으로 이루어져 있으며 산악지역의 자연공원을 관광 자원화 하여 수혜를 원하는 사람들에게 접근성이 용이하도록 정책을 활성화할 필요가 있다. 이러한 여건을 감안하고 국토의 균형발전과 철도 인프라구축 정책원칙 우선 적용을 위한 일환으로 산악지역 중 가장 실효성과 경제성이 있을 것으로 예상되는 북한산에 대해 산악관광열차로서의 도입시 이용자 지불의사 수준에 관한 대안을 적용하여 산악철도에 대한 경제성 변화를 연구 하였다. 분석결과 LIM(선형유도모터) 과 랙&피니언 시스템의 편익비용비가 각각 0.73, 0.8로 나타났으며, 랙&피니언방식이 적용가능 한 대안으로, 향후 새로운 신 기술개발이 이루어지고, 노선내 터널을 일부시공 한다면 선형유도모터방식도 가능한 대안으로 검토 되었다.

• The Korean Journal of Ceramics
• /
• 제2권4호
• /
• pp.216-220
• /
• 1996

In the present paper, a new type of DC arc plasma torch is disclosed. The principles of the new magnetic and fluid dynamic controlled large orifice long discharge tunnel plasma torch is discussed. Two series of DC Plasma Jet diamond film deposition equipment have been developed. The 20kW Jet equipped with a $\Phi$70 mm orifice torch is capable of deposition diamond films at a growth rate as high as 40$\mu\textrm{m}$/h over a substrate area of $\Phi$65 mm. The 100kW high power Jet which is newly developed based on the experience of the low power model is equipped with a $\Phi$120 mm orifice torch, and is capable of depositing diamond films over a substrate area of $\Phi$110 mm at growth rate as high as 40 $\mu\textrm{m}$/h, and can be operated at gas recycling mode, which allows 95% of the gases be recycled. It is demonstrated that the new type DC plasma torch can be easily scaled up to even higher power Jet. It is estimated that even by the 100kW Jet, the cost for tool grade diamond films can be as low as less than ＄4/carat.

• 한국지반공학회논문집
• /
• 제18권4호
• /
• pp.75-83
• /
• 2002

본 연구에서는 준설토, EPS 그리고 고화재를 혼합한 경량혼합토의 역학적 특성을 일축 및 삼축압축시험을 통하여 고찰하였다. 역학적 특성은 다양한 준설토의 초기 함수비, EPS 함유율, 시멘트 함유율 그리고 양생압력에 대한 경량혼합토의 압축강도에 대하여 연구하였다. 삼축압축상태에서 EPS를 함유한 경량혼합토의 압축강도는 유효구속압에 의존 하지 않는 것으로 나타났다. EPS 함유율이 감소할수록($A_E$<2%) 그리고 시멘트 함유율이 증가할수록($A_c$>2%) 삼축압축강도-변형 거동특성은 극한 압축강도를 지나 급격한 압축강도의 감소를 보이는 시멘트 혼합토의 압축강도-변형 거동특성과 유사한 것으로 나타났다. 200kpa 이상의 압축강도를 요구하는 개량지반에 본 경량혼합토를 적용하는 경우에서 적절한 준설토의 초기함수비, EPS 함유율은 각각 약 165%~175%이상 그리고 3%~4%이상으로 제시할 수가 있었다. 삼축 및 일축압축상태에서 극한 압축강도는 시멘트 함유율이 2%이상에서 거의 증가하지 않음으로서 한계 시멘트 함유율은 2%로 제시할 수가 있었다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제30권1호
• /
• pp.157-168
• /
• 2006

Recently, interest in using Al alloys in ship construction instead of fiber-reinforced plastic (FRP) has increased because of the advantages of A) alloy ships over FRP ships, including high speed, increased load capacity. and ease of recycling. This paper investigated the mechanical and electrochemical properties of Al alloys in a slow strain rate test under various potential conditions. These results will provide reference data for ship design by determining the optimum protection potential regarding hydrogen embrittlement and stress corrosion cracking. In general, Al and Al alloys do not corrode on formation of a film that has resistance to corrosion in neutral solutions. In seawater, however, $Cl^-$ ions lead to the formation and destruction of a Passive film. In a potentiostatic experiment. the current density after 1200 sec in the Potential range of $-0.68\~-1.5\;V$ was low. This low current density indicates the protection potential range. Elongation at an applied potential of 0 V was high in this SSRT. However, corrosion protection under these conditions is impossible because the mechanical properties are worse owing to decreased strength resulting from the active dissolution reaction in parallel parts of the specimen. A film composed of $CaCO_3\;and\;Mg(OH)_2$ confers corrosion resistance. However, at potentials below -1.6 V forms non-uniform electrodeposition coating, since there is too little time to form a coating. Therefore, we concluded that the mechanical properties are poor because the effect of hydrogen gas generation exceeds that of electrodeposition. Comparison of the maximum tensile strength, elongation, and time to fracture indicated that the optimum protection potential range was from -1.45 to -0.9 V (SSCE).

• 에너지공학
• /
• 제29권3호
• /
• pp.57-63
• /
• 2020

In this paper, we reported that the global trend of cement production and utilization as raw materials and as a fuel. As we know, cement is one of the significant materials required for the construction industry. The recent trend of rising urbanization, both the cement and construction industry played a vital role. The cement industry is a major sustainable infrastructure for the countries. Currently, China producing cement half of the world's cement production. During the year 2018, Korea producing cements nearly 57.5 million metric tons. Waste materials are used as circular resources and also having tremendous benefits for cement production. Another important use of these circular resources is fuel for the cement industry. There is a large potential benefit of the cement industry, but it's creating a severe environmental threat. The cement industry contributes to the major emissions of CO2. This leads the global warming. As per the Paris agreement, the Korean government initiated the recycling policy of waste materials and also the utilization of circular resources for the prevention of limited natural resources and also the global warming effect.

• 한국전자통신학회논문지
• /
• 제10권8호
• /
• pp.907-914
• /
• 2015

지구 온난화로 인해 온실가스 배출에 대한 규제가 강화되고 있는데, 온실가스의 주된 성분은 이산화탄소($CO_2$)이다. 건축 분야에서 $CO_2$ 발생량을 줄이기 위해서 저탄소 장수명화가 진행되고 있고 건축자재에 RFID(: Radio Frequency Identification)를 사용하여 자재관리 시스템을 구축하는 사례가 증가하고 있다. 기존의 RFID를 활용한 건축자재 관리 시스템은 건물의 신축단계에서 건설자재가 어디에 얼마만큼 사용되는지에 대한 연구와 실험이 대부분 이었고, 건물의 신축과 해체 시 재활용할 수 있는 자재에 대한 상태관리 시스템은 개발된 사례가 없다. 본 논문에서는 건물의 신축 혹은 해체 시 건설자재의 상태를 효과적으로 관리할 수 있는 RFID 시스템을 제안한다. 제안된 시스템은 900MHz 대역의 RFID를 사용하며 건축 자재 표면 또는 내부에 RFID 태그를 부착한다. 시스템의 구조는 RFID 리더부, 통신부, 저장부로 구성된다.

• 한국조경학회지
• /
• 제34권2호
• /
• pp.113-127
• /
• 2006

As the local self-government are stabilized and the environmental value is becoming more important among local residents, the occurrence of the anti-movements against waste treatment facilities is getting more frequent. Opposing to build the reuse facilities of wastes takes place because of concerning of health and hygiene, as well as matters of unclear policy making process. However, these facilities must be built in somewhere for the convenience and profit of the public. The NIMBY phenomenon against reuse facilities of wastes could be a burden for the city operation system, and it could worsen citizens' quality of life in the long run. In these lights, reuse and recycling facilities of wastes in East region are necessary facilities improving citizens' quality of life and enhancing the growth of cities in the region. However, there have been concerning of deforestation during the construction process of the facilities. The landscape design presented here for these facilities considers the features of the environmental ecosystem and tries to establish a plan to preserve the natural environment of the City of Ichon. This paper presents methods minimizing adverse effects of the facilities on the existing environments and promoting the city image with integrating culture, tourism, landscape and environment of the city. The landscape design makes efforts to harmonize natural environments in the site, human activities and culture. Well-being park was aimed to lead healthy and energetic outdoor activities of local residents. Ecological park was aimed to enhance the ecological functions of the forests and restore the valley ecology. Culture park was aimed to capture the city identity by creating a place that contains all the variety of meanings of the City of Ichon.

• Composites Research
• /
• 제18권1호
• /
• pp.55-66
• /
• 2005

페놀 컴포지트(이하 PC라 약칭)의 실용화에 대해서, 세계에서 가장 빠르게 실용화 한 $\lceil$영국의 경우$\rfloor$에 대해서 본보고서를 포함해서 합계 7편을 보고했다. 제1$\~$2편은 런던 지하철 화재사고 대책을 중심으로 세론과 행정 측의 민첩하고 신속한 대응이 시민에게 $\lceil$검은 연기와 유독가스의 화재사고$\rfloor$를 일어나지 않도록 하는 $\lceil$안전$\rfloor$을 보장한 이야기를 2회 보고했다. 제3$\~$4편은 선박$\cdot$주정, 해상 오일리그 등 역시 $\lceil$화재가 발생하면 도피하기 어려운 장소$\rfloor$에서의 실용화 상황, 제5편은 그 응용으로써 $\lceil$건설$\rfloor$ 특히 $\lceil$건축$\rfloor$ 용도에서의 실용화에 대해서 영국사회의 노력을 서술했다. 그리고 제 6편과 본편에서는 그 실용화 과정에서, 지금까지 겪은 시행착오의 기술적인 기초 데이터의 수집과 초기 실적과정에서의 어려웠던 이야기를 서술한다.

• Design & Manufacturing
• /
• 제14권2호
• /
• pp.7-13
• /
• 2020

For one decades, mobile devices components were made with plastic material, but environmental problems have recently replaced them with metal materials such as aluminum. Generally, aluminum components are mostly produced through cutting, but this process has limitations such as productivity and chip recycling. For this reason, many researches are conducted to improve productivity by replacing with the forging press process for manufacturing mobile device components. After forging process, the flash is remained and it is necessary to eliminate the flash from the final shape of components. In this paper, one-sided clearance for blanking aluminum material wes selected for parameter affected to the dimensional precision. Because the clearance is the most important parameter in blanking process. Deriving the clearance of blanking process for high dimensional precision, five level of one-sided clearance is selected and CAE is used to analyze the dimensional precision for each case.