• Earthquakes and Structures
• /
• 제12권4호
• /
• pp.397-407
• /
• 2017

To estimate the structural seismic demand, some methods are based on an equivalent linear system such as the Capacity Spectrum Method, the N2 method and the Equivalent Linearization method. Another category, widely investigated, is based on displacement correction such as the Displacement Coefficient Method and the Coefficient Method. Its basic concept consists in converting the elastic linear displacement of an equivalent Single Degree of Freedom system (SDOF) into a corresponding inelastic displacement. It relies on adequate modifying or reduction coefficient such as the inelastic deformation ratio which is usually developed for systems with known ductility factors ($C_{\mu}$) and ($C_R$) for known yield-strength reduction factor. The present paper proposes a rational approach which estimates this inelastic deformation ratio for SDOF bilinear systems by rigorous nonlinear analysis. It proposes a new inelastic deformation ratio which unifies and combines both $C_{\mu}$ and $C_R$ effects. It is defined by the ratio between the inelastic and elastic maximum lateral displacement demands. Three options are investigated in order to express the inelastic response spectra in terms of: ductility demand, yield strength reduction factor, and inelastic deformation ratio which depends on the period, the post-to-preyield stiffness ratio, the yield strength and the peak ground acceleration. This new inelastic deformation ratio ($C_{\eta}$) is describes the response spectra and is related to the capacity curve (pushover curve): normalized yield strength coefficient (${\eta}$), post-to-preyield stiffness ratio (${\alpha}$), natural period (T), peak ductility factor (${\mu}$), and the yield strength reduction factor ($R_y$). For illustrative purposes, instantaneous ductility demand and yield strength reduction factor for a SDOF system subject to various recorded motions (El-Centro 1940 (N/S), Boumerdes: Algeria 2003). The method accuracy is investigated and compared to classical formulations, for various hysteretic models and values of the normalized yield strength coefficient (${\eta}$), post-to-preyield stiffness ratio (${\alpha}$), and natural period (T). Though the ductility demand and yield strength reduction factor differ greatly for some given T and ${\eta}$ ranges, they remain take close when ${\eta}>1$, whereas they are equal to 1 for periods $T{\geq}1s$.

• 공업화학
• /
• 제30권4호
• /
• pp.509-511
• /
• 2019

정밀화학 및 의약품, 화장품에 사용되는 hydrazine 유도체는 diazonium salt로부터 환원반응을 통해 합성할 수 있다. $SnCl_2$를 이용한 환원방법은 반응 전환이 용이하나 반응 후 최종 제품에 중금속 잔류문제가 민감한 경우 사용에 제한을 받는다. 중금속이 없는 라말린(Ramalin)을 제조하기 위해 $NaHSO_3$를 이용한 환원방법을 개발하였으며, 이때 보호된 (2-hydoxyphenyl)diazonium 유도체의 diazonium 그룹을 hydrazine 그룹으로 전환하기 위한 환원반응에서, 하이드록시 그룹의 보호기 크기에 따른 입체장애 영향을 확인하였고, 보호기의 크기는 $C_1{\sim}C_5$ 직쇄형 보호기가 바람직하였다. 라말린 제조를 위한 경제성과 공업적 생산을 고려하여 다양한 보호기를 검토한 결과, 비교적 안정한 조건에서 탈보호할 수 있는 알릴 그룹을 사용할 경우 2-(allyloxy)aniline으로부터 (2-allyloxyphenyl)hydrazine를 수율 85%, 순도 99.7%로 가장 좋은 결과를 얻을 수 있었다.

• 한국식품영양과학회지
• /
• 제40권8호
• /
• pp.1184-1188
• /
• 2011

낮은 염 농도로 절임배추를 제조하고자 본 실험을 실시하였다. 전통적인 누름 방식, 감압처리 및 증기 투과 후 절임한 배추 처리구를 각각 제조하여 조직 강도 및 염도를 측정한 결과, 누름방식과 감압절임은 그 세기가 클수록 삼투현상이 상대적으로 활발해져 기계적 조직 강도가 증가함에 따라 배추 겉 표면의 뚫림 시간이 증가하였으며, 증기처리의 경우 100$^{\circ}C$에서 1분 투과 시 절임이 활성화되는 것으로 확인되었다. 그리하여 15$^{\circ}C$ 저장환경에서 배추와 천일염 6% 염수를 1:1.5 비율로 혼합하여 6시간 절임 시 1.35 $kg{\cdot}f/cm^2$의 힘을 가하거나, 250 mmHg로 감압 또는 100$^{\circ}C$에서 1분간 증기 처리한 후 절임하면 절임배추를 제조할 수 있는 것으로 확인되었다. 본 실험결과에 따라 염 첨가량과 절임시간을 낮춰 조절하면 저염 절임이 활성화될 수 있을 것이다.

• 한국분말재료학회지
• /
• 제12권1호
• /
• pp.56-63
• /
• 2005

Ag powder was prepared from $AgNO_3$ by wet chemical reduction method using various reduction agent system involving $AgNO_3$, $AgNO_2$(AgCl) and Ag complex ion aqueous solution. The pure Ag powder could be prepared regardless of reaction system but the particle shape and distribution were affected very much according to the kind of reduction agents and reaction systems. The optimum reaction system for the preparation of the silver powder having the uniform particle shape and size distribution was Ag complex ion aqueous solution-reduction agent system and in particular, $H_2O_2$ and $C_6H_8O_6$as a reduction agent leaded the more uniform particle shape and size distribution.

• 태양에너지
• /
• 제18권4호
• /
• pp.1-10
• /
• 1998

Polymer induced turbulent drag reduction in a rotating disk apparatus was investigated using four different molecular weights of poly(ethylene oxide)(PEO) in a synthetic seawater solution for the purpose of potential application to the cold water piping in the Ocean Thermal Energy Conversion(OTEC) system. To apply drag reduction to the OTEC we measured the temperature dependence on the drag reduction efficiency. From this study, it was found that the drag reduction efficiency increases with the temperature and the concentration. To measure the drag reduction efficiency during the operation period, the drag reduction behavior was detected as a function of time and the results obtained from the experiment was compared to the Brostow's model equation.

• 한국군사과학기술학회지
• /
• 제11권1호
• /
• pp.15-24
• /
• 2008

The data delivery confirmation method of MIL-STD-188-220C, which is a tactical wireless mobile Ad-Hoc communication protocol, is that a source node requires the end-to-end ack from all destination nodes and the data-link ack from 1-hop neighboring destination nodes and relaying nodes, regardless of the hop distance from a source node to destination nodes. This method has the problem to degrade the whole communication network performance because of excessive data traffic due to the duplicate use of end-to-end ack and data-link ack, and the collision among end-to-end acks on the wireless network in the case of confirming a data delivery within an 1-hop distance. In order to solve this problem, this paper has proposed the method to perform the data delivery confirmation with the improvement of communication network performance through the data traffic reduction by achieving the reliable data delivery confirmation requiring the only data-link ack within an 1-hop distance. The effects of the proposed method are analyzed in the two aspects of the data delivery confirmation delay time and the data delivery confirmation success ratio.

• 전기화학회지
• /
• 제6권3호
• /
• pp.178-182
• /
• 2003

용융탄산염형 연료전지의 특성을 결정짓는 탄산염 전해질에 있어, 기존의 Li-K와 Li-Na 탄산염과는 다른 Li-Na-K 삼원계 탄산염의 특성을 산소환원 및 산화니켈 용해거동을 통해 검토하였다. 대상 삼원계 전해질은 Li-Na-K=47.4-32.6-20, 60-20-20, 50-40-10, $40-40-20mo1\%$이었으며, $650^{\circ}C$, 1기압 조건에서 산소환원 거동은 전기화학적 방법을 통해, NiO용해거동은 화학적 방법을 통해 검토하였다 삼원계 조성에 따라 산소환원 전류치의 차이가 관찰되어, 산소용해도가 조성에 의존함을 나타내었다. 또한 $Li-Na-K = 50-40-10 mol\%$ 조성에서는 다른 형태의 산소환원 피크가 관찰되어 조성에 따라 산소환원 메카니즘의 차이가 존재할 수 있음을 시사하였다. 그러나 산화니켈 용해도는 조성에 크게 의존하지 않는 특성을 보여주었다.

• Korean Chemical Engineering Research
• /
• 제48권3호
• /
• pp.365-374
• /
• 2010

농산폐기물인 폐버섯배지의 목재 펠릿 연료화 가능성을 탐색하기 위하여 국내 발생량이 가장 많은 새송이버섯, 팽이버섯, 느타리버섯 폐배지를 대상으로 산(acid) 첨가 용매추출에 의한 회분감소 실험을 수행하였고 이에 따른 연료특성 변화를 탐색하였다. 새송이버섯 폐배지는 초산 2%(w/w), 무수구연산 1%(w/w) 첨가군, 액비 1:8, 추출온도 $55^{\circ}C$, 추출시간 180분의 추출조건에서 무처리군의 회분함유량 8.81%(w/w), 발열량 3,958.3 kcal/kg 대비 각각 3.33%(w/w), 4,219.2 kcal/kg로 성능을 극대화시킬 수 있었으며, 팽이버섯 폐배지는 초산 3%(w/w), 무수구연산 1%(w/w) 첨가군, 액비 1:8, 추출온도 $65^{\circ}C$, 추출시간 180분의 추출조건에서 무처리군의 회분함유량 14.91%(w/w), 발열량 4,190.3 kcal/kg 대비 각각 4.07%(w/w), 4,627.6 kcal/kg로 성능이 극대화되었으며, 느타리버섯 폐배지는 초산 1%(w/w), 무수구연산 1%(w/w) 첨가군, 액비 1:7, 추출온도 $65^{\circ}C$, 추출시간 180분의 추출조건에서 무처리군 대비 회분함유량이 3.31%(w/w)에서 0.59%(w/w)로 감소효과가 극대화되었고 발열량은 4,558.6 kcal/kg 대비 4,216.2 kcal/kg로 감소효과가 최소화됨으로써 성능이 극대화되었다.

• 한국염색가공학회지
• /
• 제25권3호
• /
• pp.215-222
• /
• 2013

The purpose of this study is to minimize fading fabrics of surgical gown by repeated severe laundering and sterilization condition. The study showed that the best conditions were reduction cleaning using sulphinic acid derivatives or glucose organic chemicals at $98^{\circ}C$ alkaline solutions. In these conditions, color difference values(dE) were below 1.0 that means unrecognizable color change by repeated laundering and sterilization. If it treated with only laundering, reduction cleaning conditions may adjust over $80^{\circ}C$ alkaline solution. In conclusion, it is needed to select the high-washing fastness dye and reduction cleaning using sulphinic acid derivatives or glucose organic chemicals at $98^{\circ}C$ alkaline solutions for removal unfixed dyes.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년 영문 학술대회
• /
• pp.160-167
• /
• 2008

The effects of squealer rim height on three-dimensional flows and aerodynamic losses downstream of a high-turning turbine rotor blade have been investigated for a typical tip gap-to-chord ratio of h/c=2.0%. The squealer rim height-to-chord ratio is changed to be $h_{st}/c$=0.00(plane tip), 1.37, 2.75, 5.51, and 8.26%. Results show that as $h_{st}/c$ increases, the tip leakage vortex tends to be weakened and the interaction between the tip leakage vortex and the passage vortex becomes less severe. The squealer rim height plays an important role in the reduction of aerodynamic loss when $h_{st}/c{\leq}2.75%$. In the case of $h_{st}/c{\geq}5.51%$, higher squealer rim cannot provide an effective reduction in aerodynamic loss. The aerodynamic loss reduction by increasing $h_{st}/c$ is limited only to the near-tip region within a quarter of the span from the casing wall.