A conductive additive is prepared by dispersing multi-walled carbon nanotubes (MWCNTs) on Cu powder by mechanical milling and is distributed in epoxy to enhance its electrical conductivity. During milling, the MWCNTs are dispersed and partially embedded on the surface of the Cu powder to provide electrically conductive pathways within the epoxy-based composite. The degree of dispersion of the MWCNTs is controlled by varying the milling medium and the milling time. The MWCNTs are found to be more homogeneously dispersed when solvents (particularly, non-polar solvent, i.e., NMP) are used. MWCNTs gradually disperse on the surface of Cu powder because of the plastic deformation of the ductile Cu powder. However, long-time milling is found to destroy the molecular structure of MWCNTs, instead of effectively dispersing the MWCNTs more uniformly. Thus, the epoxy composite film fabricated in this study exhibits a higher electrical conductivity than 1.1 S/cm.

SWRO-PRO hybrid desalination technology is recently getting more attention especially in large desalination markets such as USA, Middle East, Japan, Singapore, etc. because of its promising potential to recover a considerable amount of osmotic energy from brine (a high-concentration solution of salt, 60,000 – 80,000 mg/L) and also to minimize the impact of the discharged brine into a marine ecosystem. By the research and development of the core technologies of the SWRO-PRO desalination system in a national desalination research project (Global MVP) supported by Ministry of Land, Infrastructure, and Transport (MOLIT) and Korea Agency for Infrastructure Technology Advancement (KAIA), it is anticipated that around 25% of total energy consumption rate (generally 3 to 4 kWh/m3) of the SWRO desalination can be reduced by recovering the brine’s osmotic energy utilizing wastewater treatment effluent as a PRO feed solution and an isobaric pressure exchanger (PX, ERI) as a PRO energy converter. However, there are still several challenges needed to be overcome in order to ultimately commercialize the novel SWRO-PRO process. They include system optimization and integration, development of efficient PRO membrane and module, development of PRO membrane fouling control technology, development of design and operation technology for the system scaling-up, development of diverse business models, and so on. In this paper, the current status and progress of the pilot study of the newly developed SWRO-PRO hybrid desalination technology is discussed.

In the present work, a comparative study of the mechanical behavior of two series of elastomeric composites, based on carboxylated styrene butadiene rubber (X-SBR) and reinforced with rice bran carbon (RBC) and graphite, is reported. Hybrid composites of X-SBR filled with RBC-graphite were also investigated in terms of the cure characteristics, hardness, tensile properties, abrasion resistance, and swelling. It was observed that the cure times decreased with the incorporation of a carbon filler whereas the torque difference, tensile strength, tensile modulus, hardness, and swelling resistance increased compared to the neat X-SBR revealing a favorable characteristic of crosslinking. Dynamic rheological analysis showed that the G' values of the composites, upon the addition of RBC-graphite, were changed to some extent. This demonstrates that the presence of a strongly developed network of fillers will ensure a reinforcing characteristic in a polymer matrix.

Public transportation companies often classify customers into only two classes, i.e. first and second class. This segmentation largely ignores travelers’ needs and may leave heterogeneity within classes. Using a discrete choice experiment, this work investigates if the introduction of dedicated sections based on travelers’ characteristics can provide them additional value.

We examined whether hybrid consumers exist in the commodity food market by comparing food products in general, fresh pork and precooked pork patties using an online questionnaire (N=200). The same consumers changed their selection criteria depending on the type of commodity food product they were considering, reflecting hybrid consumer attitudes.

This paper presents experimental results for evaluating bond strength of FRP Hybrid Bars(HYB). In order to confirm the bond strength of HYB, direct bond strength tests were performed on 20 specimens. 20 specimens made of deformed steel bars were also tested for relative comparison. HYB and deformed steel bars were embedded in a concrete block with a size of 200 mm and different attachment lengths were applied depending on the diameter of the reinforcing bars. During the test, load and relative displacement(slip) were measured and the load-displacement behaviors of all specimens were analyzed from the measured results. The maximum bond strength of deformed steel bars were higher than that of HYB regardless of its diameter. However, after the maximum load, the deformed steel bars were more dominant than the HYB in the sudden load reduction tendency.

The ultimate goal of this development is a hybrid solar energy storage device. It supplies stable power to the load due to the emergency generator that compensates for the power shortage due to solar power generation. We have developed a stand-alone photovoltaic power generation and energy storage system with a dual inverter that extends the performance life of the PV system. It solves the problem of shortening the lifespan of battery due to repetition of charge / discharge of PV system and supplies stable power to load due to emergency generator that compensates for power shortage due to solar power generation, and furthermore, A stand-alone photovoltaic power generation system having a dual inverter for extending the life span and a control method thereof. We have also developed an optimized energy solution that enables us to save and use the remaining surplus power in the ESS to save energy through efficiency, optimization and substantial energy savings.

본 총설은 다양한 저널 게재 논문으로부터 분리막 및 광촉매의 혼성 정수/하수 처리 공정을 요약하였다. 이 총설에는 (1) 분리막 광촉매 반응기(membrane photoreactor, MPR), (2) 분리막 결합 광촉매 공정에서 막오염 관리, (3) 유기 오염 물의 분해를 위한 광촉매 분리막 반응기, (4) 정수처리용 막분리 공정과 광촉매 분해의 결합, (5) 휴믹산 분해를 위한 광촉매 및 세라믹 막여과의 혼성공정, (6) 활성슬러지 여과를 위한 한외여과의 막오염에 이산화티타늄 나노입자의 영향, (7) 정수처 리용 광촉매 및 정밀여과의 혼성시스템, (8) 선박 평형수 처리용 한외여과 및 광촉매의 혼성공정 및 (9) 분리막 및 광촉매 코팅 프로필렌 구의 혼성수처리 공정이 포함되어 있다.

본 연구는 통합공정일정계획(Integrated Process Planning and Scheduling; IPPS)의 최적화를 위한 계산 효율성이 높은 탐욕적 휴리스틱과 유전알고리즘(Genetic Algorithm; GA)을 결합한 하이브리드형 유전 알고리즘을 제안한다. IPPS는 기존의 공정계획과 일정계획을 동시에 풀고자 하는 NP-Hard 문제이다. 특히, 본 연구에서 다루는 IPPS는 tool related constraints가 포함된 것으로서 전통적인 GA는 수행도중 infeasible schedule을 빈번히 발생시킨다. 제안하는 방법의 아이디어는 전체적인 schedule의 구조에 영향을 미치는 operation의 sequence와 machine의 결정은 GA의 procedure를 따르고, 목적함수의 부분계산이 가능한 tool과 Tool Access Direction(TAD)는 greedy heuristics을 통하여 infeasibility를 해소하자는 것이다. 이를 통하여 계산시간의 급격한 증가 없이 또는 기존에 비해 계산시간을 감소시키면서 좋은 품질의 해를 구할 수 있다. 본 연구에서 제안하는 알고리즘은 benchmark problems을 이용하여 성능을 평가한다.

Structure behaviors resulting from an earthquake are experimentally simulated mainly through a shaking table test. As for large-scale structures, however, size effects over a miniature may make it difficult to assess actual behaviors properly. To address this problem, research on the hybrid simulation is being conducted actively. This method is to implement numerical analysis on framework members that affect the general behavior of the structure dominantly through an actual scale experiment and on the rest parts by applying the substructuring technique. However, existing studies on hybrid simulation focus mainly on Slow experimental methods, which are disadvantageous in that it is unable to assess behaviors close to the actual level if material properties change depending on the speed or the influence of inertial force is significant. The present study aims to establish a Real-time hybrid simulation system capable of excitation based on the actual time history and to verify its performance and applicability. The hybrid simulation system built up in this study utilizes the ATS Compensator system, CR integrator, etc. in order to make the target displacement the same with the measured displacement on the basis of MATLAB/Simulink. The target structure was a 2-span bridge and an RC pier to support it was produced as an experimental model in order for the shaking table test and Slow and Real-time hybrid simulations. Behaviors that result from the earthquake of El Centro were examined, and the results were analyzed comparatively. In comparison with the results of the shaking table test, the Real-time hybrid simulation produced more similar maximum displacement and vibration behaviors than the Slow hybrid simulation. Hence, it is thought that the Real-time hybrid simulation proposed in this study can be utilized usefully in seismic capacity assessment of structural systems such as RC pier that are highly non-linear and time-dependent.

For facilitated olefin/paraffin separation, poly(ethylene-alt-maleic anhydride)-g-O-(2-aminopropyl)-O′-(2-methoxyethyl) polypropylene glycol (PEMA-g-PPG) is reported by facile, cheap and moderate-condition synthesis. PEMA-g-PPG provided effective polymer matrix for partially polarized silver nanoparticles (AgNPs) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). AgNPs could facilitate olefin transport through π-complexation, while TCNQ activated surface of AgNPs for partial polarization as a strong electron acceptor. The FT-IR and TEM image supported improved interactions between PEMA-g-PPG and AgNPs. The best separation performance was obtained with 1:3 wt ratio of PEMA-g-PPG:AgNPs, showing 7.8 GPU for mixed gas permeance and 17.5 selectivity for propylene/propane.

최근 국내에서 연구개발중인 SWRO-PRO 복합해수담수화 기술은 SWRO 해수담수화 플랜트에서 발생하는 고염도 농축수와 저염도 하수처리수를 각각 PRO 시스템의 유도용액과 원수로 사용하여, 두 용액의 농도차에 의해 발생되는 삼투에너지를 압력교환장치를 통해 회수하여 RO 고압펌프에서 필요한 에너지를 줄이거나, 터빈 형태의 에너지 회수장치 적용을 통해 전력을 생산하는 기술이다. PRO 시스템을 통해 회수된 에너지는 해수담수화 운영비를 절감할 수 있고, 고농도 농축수 방류로 인한 해양생태계 영향을 최소화 시킬 수 있다. 또한, 농축수 처리 비용 및 해수담수화 전력시설 비용을 절감시키는 효과를 기대할 수 있다.

분리막에 관한 최신의 연구에서는 다양한 분야의 기술을 분리막 분야에 차용하여, 분리막의 성능을 증진시키고 있다. 특히 나노기술과 분리막 제조 기술의 융합연구는 최신 분리막 연구 분야의 하나로 주목받고 있으며, 다양한 나노-하이브리드 분리막이 연구되고 있다. 본 연구에서는 1) 패터닝 기술을 도입한 패턴 분리막의 제조 - 나노 기술의 하나인 패터닝 기술을 분리막 제조 공정에 융합하여, 표면이 패턴화된 분리막을 제조하고 그 성능을 평가하였다. 2) MIL-100(Fe)/CS 등의 나노 입자를 포함하는 분리막의 제조 - 특별한 목적을 가지고 있는 나노입자(MIL-100(Fe)/CS의 경우 항균성 및 친수성)를 분리막 제조에 적용하여 분리막의 막오염 저감 효과를 증진한 분리막을 제조하였다. 에 대한 연구 결과를 발표하고자 한다.

Pressure-retarded osmosis (PRO) is one of the promising candidates to reduce the reliance on fossil fuels by harnessing energy from the salinity gradient between high-saline and low-saline water. Based on recent advances in the membrane technologies, PRO has re-emerged as a potentially viable energy option. However, several challenges still remain before PRO can reach the commercial stage. Within this context, the objective of this research was to assess the techno-economic feasibility of PRO and PRO-hybrid processes. In particular, model-based performance analysis were conducted for the PRO-hybrid systems. In addition, the influence of colloidal fouling on the performance of PRO process was further investigated. It is expected that this research would help comprehensively understand the PRO-hybrid processes thereby activate further development.

In this study, the long-term performance of FRP Hybrid Bar made by hybridizing FRP (Fiber Reinforced Polymer) with ordinary reinforcing steel bars was experimentally examined as a part of the development of alternative materials for RC (reinforced concrete) structures especially located in marine or harbor areas. In order to evaluate the field exposure of the FRP Hybrid Bar, the specimen was prepared and the corrosion behavior was evaluated by letting the specimen exposed to the field conditions in the west coast of South Korea. The purpose of this study is to provide important data as a material countermeasure to reduce corrosion of reinforcing steel in future marine port concrete structures based on the results obtained through this study.