B4C/Al composite is mainly used for neutron absorbing materials, which is one of the components of equipment that manages spent nuclear fuel. There are various processes for manufacturing neutron absorbing materials, but most of them are based on the powder metallurgy. In this study, B4C/Al composite in which the reinforcement was uniformly dispersed was manufactured by using the stir casting process. The microstructure, thermal neutron absorption rate, mechanical properties and dispersibility of the reinforcement of the prepared B4C/Al composite were analyzed.

In this study, for thermal neutron absorption, an aluminum metal composite in which B4C particles were uniformly dispersed was prepared using stirring casting and hot rolling processes. The microstructure, thermal neutron absorption rate, mechanical properties and dispersibility of the reinforcement of the prepared B4C/Al composite were analyzed. The composite in which the 40 μm sized B4C particles were uniformly dispersed increased the tensile strength as the volume ratio of the reinforcement increased.

Shopping at bricks-and-mortar stores is considered highly experiential. An ability to experience and physically interact with a product is a key benefit of shopping at offline stores. In an online shopping context where sensory experience is absent, researchers have looked at how mental imagery as an alternative to in-store sensory experience impact consumer decision-making (Yoo & Kim, 2014). However the role of mental imagery has been largely overlooked in the context of offline store shopping. While it is true that shopping at offline stores facilitates sensory experience, evidence from cognitive neuropsychology literature supports that visual perception impacts visual mental imagery (Bartolomeo, 2002). Therefore, it is reasonable to posit that sensory experience in stores is related to mental imagery. Yet the relationship between actual sensory experience and mental imagery in the context of store shopping has not been studied. To fill a gap in the current literature, this study aims to examine the process by which sensory experience and mental imagery facilitate purchase decision-making in the context of offline stores. Based on the model of recursive relationships among consumers’ emotional, cognitive, perceptual and behavioral responses (Scherer, 2003) and a review of previous literature, this study posits that actual sensory experience and mental imagery related. It is further posited that both actual sensory experience and mental imagery influence consumers’ affective (anticipatory emotion) and cognitive responses (e.g., decision satisfaction, perceived ownership and decision satisfaction). This study employed an online survey in Korea. Apparel shoppers who shopped and purchased apparel at brick-and-mortar stores during the last six months were recruited. To facilitate a retrieval of in-store experiences, a series of questions about their specific shopping trip and purchases were asked at the beginning of survey. The current study consists of measurements adopted from the existing literature with adequate reliabilities. All the items were measured using a 7-point Likert-type scale. A total of 455 respondents completed the online survey questionnaire. Cronbach’s alpha coefficients were examined to assess reliabilities of the measures, and reliability coefficients were acceptable for all constructs (.78 ~ .92). Results of the SEM revealed that all the model-fit indexes exceeded their respective common acceptance levels, suggesting that the proposed model fitted the data well (2 = 627.38, df = 175; NFI = .92; IFI = .94; CFI = .94; RMSEA = .075). All the direct relationships among variables were significant except for the effect of sensory experience on perceived ownership, the effect of mental imagery on decision confidence, and the effect of perceived ownership on behavioral intention. This study provides new insights into consumer in-store shopping experiences and theoretical and practical implications. Sensory experience and mental imagery are complementary in facilitating consumer in-store shopping experiences. In addition to the importance of sensory experience, this study provides empirical evidence to support the vital role of mental imagery in the context of in-store shopping. Visualizing a situation through vivid mental imagery combined with actual sensory experience will lead consumers to positive shopping outcomes. Further research is warranted to better understand how to optimize actual sensory experience and mental imagery to offer excellent in-store experiences.

본 연구는 차세대 에너지원으로 주목 받고 있는 직접메탄올연료전지(Direct Methanol Fuel Cell, DMFC)에 대해 mutiscale 기법을 사용하여 DMFC의 MEA부분에 대한 상세 모델링 및 전산모사를 통한 이론적 고찰을 시도하였다. 본 연구에서 이용한 multiscale 모델링 방법은 공정시스템 공학의 kinetic 중심의 모델링 방법과 전산유체역학(Computational Fluid Dynamics, CFD)의 유동중심의 모델링 방법을 유기적으로 결합하여 모사 중간에 필요한 데이터 교환을 함으로써 정확한 모델링 및 전산모사 결과를 얻었다. CFD 모델링으로 유체 이동현상을 3차원으로 해석하였고, 동시에 복잡한 비선형 대수방정식으로 표현되는 반응속도, 전기화학반응을 DAE (Differential & Algebraic Equation) solver로 계산하였다. 모델은 메탄올의 산화반응과 산소의 환원반응을 중심으로 MEA (Membrane Electorde Assembly)부분에서 물리화학적, 전기적 현상 현상을 규명하고, 반응 메커니즘을 구성하였다. MEA 모델은 3차원 공간에서 변위를 가지는 3차원 모델로 구성하였으며, 정상상태 및 등온공정의 조건하에 수립되었다. 이를 통해 channel을 포함한 MEA 부분에서 발생되는 물리적, 화학적, 전기적 현상을 정확히 예측 할 수 있다. 본 연구를 통해 수행된 결과는 DMFC의 실험계획 및 운전조건을 도출함에 있어 매우 유용한 역할을 할 수 있을 것으로 사료되며, 추가적인 연구를 통해 DMFC의 상용화에 크게 이바지 할 수 있을 것으로 사료된다.

Chemical batch tests were conducted to investigate the amount of nutrients that were released from the wasted activated sludge during microwave heating. For this study, three types of activated sludge were obtained from A2/O, MLE and oxidation ditch (OD) processes. Polyphosphate-accumulating organisms in the activated sludge have a unique trait: they releases phosphate from the cell when they are exposed to high temperatures. The sludge obtained from the A2/O process released the largest amount of phosphate, followed by those from the MLE and OD processes. The release of phosphate increased with increasing polyphosphate content in the sludge under strongly alkaline or acidic conditions. Furthermore, ammonia and heavy metals were released with phosphorous. The largest amount of ammonia was observed from the sludge obtained from the MLE process. The release of heavy metals strongly depends on the pH conditions. Therefore, the chemical analysis results strongly suggest that both phosphorus and ammonia react with Mg2+ or Ca2+ to form metal complexes such as magnesium ammonium phosphate or hydroxyapatite under alkaline conditions.

This study was conducted to investigate the feasibility of nutrient recovery and reuse from centrate, which was produced by the centrifugal dewatering of anaerobic digested sludge. A continuous stirred reactor was operated for 3 months to recover phosphorous and nitrogen as magnesium ammonium phosphate (MAP) crystals from the centrate. More than 95% of phosphate could be recovered from the centrate into the crystalline materials. The contents of TP and TN in the crystalline materials were 28.1% and 5.17%, respectively. Some heavy metals were identified, but remained under Korean standards for organic fertilizer. On the other hand, X ray diffraction analysis clearly showed that the crystalline materials was MAP crystals. However, chemical analyses suggested that some undesirable crystals like magnesium potassium phosphate or hydroxyapatite might be formed during the MAP crystallization. Nevertheless, both results strongly confirmed that the MAP crystals could be a useful and valuable nutrient fertilizer, which slowly and continuously releases essential nutrients in response to the demand from farming and planting.