일반적으로 전기변색소자들은 전기변색물질, 전해질 그리고 상대전극물질로 구성되어 있다. 그 중에서, 상대전극물질은 소자의 장기전환 안정성 및 낮은 작동 전압 등과 같은 전기변색소자들의 성능을 향상하는데 매우 중요하다. 본 연구에서는 다이메틸 프탈레이트 기반 전기변색소자에 페로센과 카본 전극을 적용하고 그 성능을 테스트 하였다. 특히 카본 전극에서 우수한 장기전환 안정성이 구현되었다.

본 연구에서는 3차원 순환 모델인 MOHID (MOdelo HIDrodinâmico) 모델을 적용하여 한반도를 포함한 동아시아 해역의 2016년 해황 변동을 재현하였다. 재현 결과는 객관 분석장(EN4, ARMOR3D, AVISO, SIO 자료)과 현장 관측 자료(정선 해양 자료, 부이 자료)를 사용하여 검증하였다. 검증 결과 MOHID로 재현된 수온, 해면 고도 편차, 표층 유속 및 혼합 층 깊이 등의 전반적인 해황 구조가 동아시아 해역의 객관 분석 자료들과 유사하게 나타났다. 특히 연안의 부이 자료와 비교하였을 때, 표층 수온 및 해면 고도 편차의 상관 계수는 모두 0.8 이상이며, 표준화된 표준편차는 0.85-1.15의 값을 보였다. 그러나 여름철 동해의 수온 약층의 구조 및 황해와 남해의 강한 성층 현상 재현에 관한 추가적인 개선이 필요할 것으로 분석되었다.

PURPOSES : The purpose of this study was to suggest a quantitative trend of the daily and seasonal cyclic movement of transverse crackwidth based on measurements in CRCP(Continuously Reinforced Concrete Pavement) within the first year of construction. METHODS : Crack gauges were installed in eight normal cracks, two induced cracks, and two construction joints of newly constructed CRCP. Crack width movements were continuously collected for about a year to investigate the cyclic behavior after construction. The daily and seasonal crack width movements were quantitatively analyzed and compared. RESULTS: Crack width movement in hot weather was relatively less than in cold weather. As a result of frequency analysis of the daily cyclic behavior, it was revealed by measurement that the minimum crack width from 2 p.m. to 4 p.m. was caused by expansion of the concrete; and that the maximum width from 6 a.m. to 8 a.m. was caused by contraction. Average crack width movements were calculated for every month and showed seasonal cyclic behavior. Maximum crack width was measured from December to January. Average crack width was investigated from March to April. Daily crack width movement in relation to concrete temperature was calculated from -0.00017 to -0.03844 mm/℃ and showed gradual decrease in absolute value with time caused by change in the crack spacing. It was found that the relationships between the monthly average crack width and concrete temperature are from -0.004 to -0.012 mm/℃. CONCLUSIONS : Crack-width movement shows a daily and seasonal cyclic behavior. Crack-width measurement in any time or season will have variance caused by daily and seasonal cyclic movement. Variances and trends were obtained in this study based on measurements for various cracks. The long-term behavior of cracks should be surveyed and compared with these measurements to investigate trends of convergence with time, caused by convergence of crack spacing.

PURPOSES : The objective of this study was to evaluate the field applicability of chip seals using recycled aggregates by comparing performance between natural aggregates and recycled aggregates for chip seals. METHODS : In order to check the performance of chip seals using recycled and natural aggregates, Bitumen Bond Strength (BBS) test, Vialit and bleeding tests were carried out. Cationic emulsions (RS(C)-2 and latex modified RS(C)-2L) were used in the tests. Granite aggregates were used as the natural aggregate and recycled aggregate from road wastes were used as the recycled aggregate. The aggregate was used with uniform gradation between 10 mm and 4.75 mm to clearly compare the performance difference between natural and recycled aggregates. RESULTS : Test results showed that the aggregate retention was low for both natural and recycled aggregates when applying RS(C)-2 (unmodified emulsion), but there was almost no difference between them when applying RS(C)-2L and RS(C)-2L-1 (modified emulsion) in the Vialit test results. In the bleeding tests, there was no bleeding for both natural and recycled aggregates when applying RS(C)-2 and RS(C)-2L. CONCLUSIONS: It was possible to apply chip seals using recycled aggregates in the field because the chip seals with recycled aggregates and RS(C)-2L (modified emulsion) showed aggregate retention similar to that of natural aggregates, and there was no bleeding.

Recycled aggregate is a solution to reduce construction waste and to be environmentally friendly, but concrete using it has various disadvantages in terms of structure. Therefore, the interaction effect of the two materials can be expected by filling the cyclic aggregate concrete in the CFT column. Eighteen specimens were constructed to confirm the compressive behavior of RCFT (Recylced Concrete Filled Tube) columns, which can be applied to real buildings by making high strength concrete with recycled aggregate. Variable is the shape and thickness of steel pipe, concrete strength and mixing ratio, and coarse aggregate and fine aggregate are all used as recycled aggregate. A total of three recycled aggregate concrete preformulations were used to find the optimal mixing ratio and the compressive behavior was analyzed through the load - displacement curves of RCFT columns.

In this paper, we propose an Elman recurrent neural network to predict and analyze a time series of gas energy consumption in an air handling unit. To this end, we consider the volatility of the time series and demonstrate that there exists a correlation in the time series of the volatilities, which suggests that the gas consumption time series contain a non-negligible amount of the non-linear correlation. Based on this finding, we adopt the Elman recurrent neural network as the model for the prediction of the gas consumption. As the simplest form of the recurrent network, the Elman network is designed to learn sequential or time-varying pattern and could predict learned series of values. The Elman network has a layer of “context units” in addition to a standard feedforward network. By adjusting two parameters in the model and performing the cross validation, we demonstrated that the proposed model predicts the gas consumption with the relative errors and the average errors in the range of 2%~5% and 3kWh~8kWh, respectively. The results of this study can be used to the energy management system in terms of the effective control of the cross usage of the electric and the gas energies.

Concrete using recycled aggregate instead of natural aggregate reduces environmental waste and is a future oriented material. However, use of the structure is limited to negative recognition of recycled aggregate quality. In this study, 50 MPa concrete was developed using recycled aggregate. In order to verify the possibility of using as a column member, we aimed to confirm the compressive behavior of RCFT (Recycled Concrete Filled Tube) columns filled with concrete using recycled aggregate. Circular type steel pipe was used, and concrete strength (30, 40, 50MPa) and mixing ratio were the experimental parameters. Through 72 specimen compression tests, 50MPa strength of recycled aggregate concrete was confirmed and stable behavior of 9 RCFT columns was confirmed.

In this paper, we propose an Elman recurrent neural network to predict and analyze a time series of power energy consumption. To this end, we consider the volatility of the time series and apply the sample variance and the detrended fluctuation analyses to the volatilities. We demonstrate that there exists a correlation in the time series of the volatilities, which suggests that the power consumption time series contain a non-negligible amount of the non-linear correlation. Based on this finding, we adopt the Elman recurrent neural network as the model for the prediction of the power consumption. As the simplest form of the recurrent network, the Elman network is designed to learn sequential or time-varying pattern and could predict learned series of values. The Elman network has a layer of “context units” in addition to a standard feedforward network. By adjusting two parameters in the model and performing the cross validation, we demonstrated that the proposed model predicts the power consumption with the relative errors and the average errors in the range of 2%~5% and 3kWh~8kWh, respectively. To further confirm the experimental results, we performed two types of the cross validations designed for the time series data. We also support the validity of the model by analyzing the multi-step forecasting. We found that the prediction errors tend to be saturated although they increase as the prediction time step increases. The results of this study can be used to the energy management system in terms of the effective control of the cross usage of the electric and the gas energies.

Recently, redevelopment and reconstruction projects have caused problems such as depletion of natural aggregates, and the use of recycled aggregate is being reevaluated as an optimal alternative. Therefore, in this study, the mechanical and deformation characteristics of Environment-Friendly Recycled Coarse Aggregate (here after, EFRCA) concrete reinforced with para-aramid fiber with high strength and high elasticity are examined. The experimental main parameters were EFRCA replacement ratio (0, 30 and 50%) and para-aramid fiber volume fraction (0, 0.75 and 1.0%). Experimental results show that the EFRCA concrete has lower compressive strength than plain concrete. However, compared with the natural aggregate, the EFRCA concrete, which exhibited low material properties, showed almost the same performance as plain concrete, such as increased flexural strength and improved ductility by incorporating para-aramid fibers. Through the experiment, it is considered that the most suitable para-aramid volume fraction is 0.75%. Based on these results, the experimental results related to the performance degradation of EFRCA concrete containing para-aramid fibers are secured and basic data for determining the reuse possibility and reinforcement method of structures are presented.

본 연구에서는 순수와 유사한 밀도의 세척형 구형 입자를 제작하고 순수 수조 내에서 산기량 및 입자 농도에 따른 입자의 유동 속도를 측정하였다. 세척형 구형 입자 1~3%를 MLSS 8,000 mg/L인 활성슬러지 용액에 주입하고 20 LMH 및 산기량 500 mL/min 조건에서 FR 및 SFCO 모드로 동시에 투과 실험하였다. 사용한 분리막은 유효 막면적이 90 cm2, 공칭 세공크기가 0.4 μm인 평막이다. 입자 농도가 증가할수록 TMP가 감소하였으며 FR 모드, 입자 농도 2%일 때 가장 효과적 인 것으로 확인되었다.

본 연구는 50대 비만중년여성을 대상으로 순환운동이 건강체력, 혈압 및 혈관탄성도에 미치는 영향을 규명하는데 있었으며, 이를 위해 비만중년여성 24명을 대상으로 운동그룹 12명, 대조군 12명으로 분류하여 8주간 순환운동 프로그램을 실시하였다. 순환운동 프로그램은 유산소 운동과 저항운동으로 구성 되었으며, 회당 40분간, 주3회 실시하였고, 유산소 운동 수행강도는 50-70% HRmax, 저항운동은 1-RM 의 40-60%로 수행되었으며, 순환운동 전·후에 측정한 자료의 그룹 내 차이 비교를 위해 대응표본 T검정, 그룹 간 차이는 운동 전·후의 변화율을 산출하여 독립표본 T검정을 실시하였다. 그 결과 운동그룹은 건강 체력 중 BMI(p<.05)가 유의하게 감소하였고, 심폐지구력(p<.001), 근지구력(p<.001), 유연성(p<.01)이 증가하였으며, 그룹 간 대조군 보다 심폐지구력, 유연성이 유의하게 증가되었다(p<.01). 수축기 혈압과 이완기 혈압은 운동그룹이 유의하게 감소하였으며(p<.01), 이완기 혈압은 그룹 간 대조군 보다 운동그룹이 유 의하게 감소하였다(p<.05). PWV는 운동그룹이 유의하게 감소하였고(p<.05), 대조군이 유의하게 증가하였으며(p<.01), 그룹 간 대조군 보다 운동군이 유의하게 감소하였다(p<.05). 이상의 결과 비만중년여성의 건강증진 및 비만치료를 위한 순환운동은 건강체력, 혈압 및 혈관탄성도에 긍정적인 영향을 미친 것으로 사료된다.

본 연구는 방울토마토 재배 단동온실에 공기순환팬을 설치하고 공기순환팬이 온실 내 온도 및 습도 분포, 에너지소비량에 미치는 영향을 분석하였다. 공기순환팬은 날개 크기 230mm의 Stainless 팬으로, Lee 등(2016)의 연구결과를 참고하여 시험구 온실에 9m 간격으로 총 18 대를 설치하였다. 온실 내부 온습도는 온실 길이방향으 로 4등분하여 1/4 지점과 3/4 지점의 중앙에 센서를 설치하고 0.8m, 1.8m 높이 2곳의 온습도를 난방을 주로 하는 야간(오후 6시~다음 날 오전 7시)에 5분 간격으로 측정하였다. 에너지소비량은 각 온실에 위치한 온수펌프의 유량, 온수 출수부와 환수부의 온도차를 측정하여 계산하였다. 공기순환팬을 사용하지 않았을 때 측점 간 온도차 및 습도차의 평균값은 0.75oC, 2.19%였으며 공기 순환팬 사용 시 측점 간 온도차 및 습도차의 평균값은 0.42oC, 1.27%로 감소하였다. 공기순환팬 설치 온실과 미설치 온실의 누적 에너지소비량은 각각 4,673kWh, 4,009kWh로 공기순환팬 설치 온실에서 약 14.2%의 에너지를 적게 소모하였다. 이러한 결과로 보아 온실 내 공기순환팬 사용은 공기를 지속적으로 교반시켜 주어 온실 전체의 온도 및 습도를 균일하게 만들고, 공기의 온도가 빠르게 변하지 않도록 해주어 난방 장치의 가동 시간과 에너지소비량을 줄일 수 있다.

This papers focuses on remanufacturing processes in a closed loop supply chain. The remanufacturing processes is considered as one of the effective strategies for enterprises’ sustainability. For this reason, a lot of companies have attempted to apply remanufacturing related methods to their manufacturing processes. While many research studies focused on the return rate for remanufacturing parts as a control parameter, the relationship with demand certainties has been studied less comparatively. This paper considers a closed loop supply chain environment with remanufacturing processes, where highly fluctuating demands are embedded. While other research studies capture uncertainties using probability theories, highly fluctuating demands are modeled using a fuzzy logic based ambiguity based modeling framework. The previous studies on the remanufacturing have been limited in solving the actual supply chain management situation and issues by analyzing the various situations and variables constituting the supply chain model in a linear relationship. In order to overcome these limitations, this papers considers that the relationship between price and demand is nonlinear. In order to interpret the relationship between demand and price, a new price elasticity of demand is modeled using a fuzzy based nonlinear function and analyzed. This papers contributes to setup and to provide an effective price strategy reflecting highly demand uncertainties in the closed loop supply chain management with remanufacturing processes. Also, this papers present various procedures and analytical methods for constructing accurate parameter and membership functions that deal with extended uncertainty through fuzzy logic system based modeling rather than existing probability distribution based uncertainty modeling.

The autoignition characteristics of n-heptane/n-butanol were investigated both experimentally and numerically. The effects of oxygen concentration and exhaust gas recirculation rate on the autoignition characteristics were evaluated. A rapid compression machine was employed to measure ignition delay times of blended fuels. A numerical study on the ignition delay time was performed using the CHEMKIN-PRO software to calculate ignition delay time and predict the chemical species in the combustion process. The results revealed that the ignition delay time increased with decreasing oxygen concentration due to the thermal load effect of nitrogen. The oxidation reaction of n-heptane in a low temperature regime was limited with decreasing oxygen concentration. The ignition delay time sharply decreased with exhaust gas recirculation because of the intermediate species in the exhaust gas. Exhaust gas recirculation reduced first ignition delay dramatically. However, the time interval between the first and main ignition increased with increased exhaust gas recirculation.