• 방사선산업학회지
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• 제5권2호
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• pp.179-184
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• 2011

In this study, several anion exchange membranes were successfully prepared by radiation grafting of vinylbenzyl chloride (VBC) monomer onto a polyethylene-co-tetrafluoroethylene (ETFE) film and subsequent quaternarization with diamins such as 1,4-diazbicyclo[2,2,2]octane, N,N,N',N'-tetramethyl-1,3-diaminopropane, N,N,N',N'-tetramethyl-1,6-diaminohexane, and trimethylamine. The anion exchange capacities of the prepared membranes were determined by using acid-base titration method. The cross-sectional morphology of the membranes was studied by using SEM instrument. The cross-sectional distribution patterns of the grafted polymers with anion exchange functional groups were also studied by EDX analysis.

• 펄프종이기술
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• 제42권2호
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• pp.1-11
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• 2010

The possibility of applying birchwood xylan in papermaking process to improve dry strength of paper was investigated. Unmodified xylan barely adsorbed onto pulp fibers while cationically modified xylan adsorbed substantially. Adsorption of cationically modified xylan by quaternarization with 3-chloro-2-hydroxypropy trimethylammonium chloride improved dry strength of paper. Chemical structure and degree of substitution of the cationically modified xylan was determined by 400 MHz 13CNMR spectroscopy and elemental analyzer. The amount of adsorbed xylan on cellulose fibers was greater when the cationicity was moderate, and it was interpreted that the conformation of this cationic xylan adsorbed on fiber surface was more favorable for greater adsorption due to its greater loop formation tendency while highly cationic xylan tends to adsorbed in stretched conformation. The physical properties of handsheets increased as the amount of adsorbed cationic xylan increased. On the other hands, the optical properties decreased with xylan adsorption.

• 한국수소및신에너지학회논문집
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• 제29권5호
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• pp.458-465
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• 2018

This study reports the fabrication of anion exchange membranes (AEMs) containing two kinds of functional groups: i) trimethylphosphite (TMP) and ii) trimethylamine (TMA). We carried out the synthesis of polymers to enhance thermal stability and ion conductivity. The alternative polymer was prepared using 2,2-bis(4-hydroxy-3-methylphenyl)propane and decafluorobiphenyl. The membrane was fabricated by solution casting method. The thermal stability of membranes was examined by TGA. The physiochemical properties of membranes were also investigated in terms of water uptake, swelling ratio, ion exchange capacity, and ion conductivity. The hydroxide ion conductivity of the membranes reached about 20.2 mS/cm for quaternary ammonium poly(arylene ether) (QA-PAE) containing TMA moiety and 5.1 mS/cm for quaternary phosphonium PAE (QP-PAE) containing TMP moiety at $90^{\circ}C$.

• 한국경제지리학회지
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• 제1권2호
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• pp.85-102
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• 1998

최근 서울 도심부는 많은 변화를 겪고 있다. 서울경제의 기반이 3차 산업과4차 산업으로 변모하면서 도시산업구조가 재편되고 있다. 사업서비스산업이 급속히 성장하고 그 수요에 발 맞추어 대규모 도심재개발사업이 진행되고 있다. 이제 도심의 사무활동은 서울경제 발전의 핵심적인 부문으로 등장했으며 도심 고층건물의 스카이라인은 서울의 경제변화를 주도하고 있다고 해도 과언은 아니다. 서울의 사무활동과 사무빌딩의 입지가 강남과 영등포 등의 신도심으로 분산되고 있는 경향이 보고되고 있기는 하나 주요 사무활동은 여전히 도심지역에 집중하고 있다 이 논문에서는 사무활동을 협의로 정의하고 사무빌딩도 상업, 교육활동 등을 제외한 본래적 의미의 업무빌딩만으로 한정하여, 그 입지변화상을 추적하고 특성을 파악한다. 서울의 사무활동은 공간분업적 집중과 분산이라는 유형을 보이고 있으며, 전반적인 분산화경향에도 불구하고 핵심적인 조정 .통제기능은 여전히 도심지역에 집중하고 있다. 이사적.기능적 통합을 통해 새로운 제조-유통-사무활동의 집적지를 형성하고 집적의 이익을 향유하기 때문에 계속된다. 특히 도심이라는 장소적 특성이 오랜 세월의 축적과 함께 도시의 문화경제를 형성하여 서울의 도시경쟁력 향상과 도시의 지역적 전문화를 촉진하고 있다. 도시공간정책은 이러한 도심지역의 특성화를 촉진하는 방향으로 이루어져야 할 것이다.