• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2384-2393
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• 2018

Porous alginate-based hydrogel beads (porous ABH) have been prepared through a facile and sustainable template-assisted method using nano-calcium carbonate and nano-$CaCO_3$ as pore-directing agent for the efficient capture of methylene blue (MB). The materials were characterized by various techniques. The sorption capacities of ABH towards MB were compared with pure sodium alginate (ABH-1:0) in batch and fixed-bed column adsorption studies. The obtained adsorbent (ABH-1:3) has a higher BET surface area and a smaller average pore diameter. The maximum adsorption capacity of ABH-1:3 obtained from Langmuir model was as high as $1,426.0mg\;g^{-1}$. The kinetics strictly followed pseudo-second order rate equation and the adsorption reaction was effectively facilitated, approximately 50 minutes to achieve adsorption equilibrium, which was significantly shorter than that of ABH-1:0. The thermodynamic parameters revealed that the adsorption was spontaneous and exothermic. Thomas model fitted well with the breakthrough curves and could describe the dynamic behavior of the column. More significantly, the uptake capacity of ABH-1:3 was still higher than 75% of the maximum adsorption capacity even after ten cycles, indicating that this novel adsorbent can be a promising adsorptive material for removal of MB from aqueous solution under batch and continuous systems.

• Bulletin of the Korean Chemical Society
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• 제28권5호
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• pp.805-810
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• 2007

Molecular recognition for a specific cation depending on the change of the oxidation state of the metal catalyst component contained in the hydrogel network has been studied in a self-oscillating hydrogel. The selfoscillating hydrogels are synthesized by the copolymerization of N-isopropylacrylamide (NIPAAm), lead methacrylic acid (Pb(MAA)2), and Ru(bpy)3 2+ monomer as a metal catalyst component. The recognition for a specific cation (in this study, Ca2+ has been used) is characterized by the adsorbed amount of Ca2+ into the gel. The recognition of the gels for Ca2+ is higher at the temperature below the LCST, and also higher at the oxidized state than at reduced state of the metal catalyst component which corresponds to a more swollen state. Moreover, a propagating wave induced by a periodic change of the oxidation state with the diffusion phenomena in the oscillating hydrogel shows a possibility for temporal and site-specific molecular recognition due to the local swelling of the gel.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.218-224
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• 2014

In order to explore new coordination frameworks with novel designed 3-nitrophthalic acid and the same N-donor ancillary ligand, a series of novel coordination complexes, namely, $[Cd_2(3-NPA)_2(TBZ)_2(H_2O)_2]{\cdot}2H_2O$(1), $[Zn_2(3-NPA)_2(TBZ)_2]$(2), $[Zn_2O(3-NPA)(TBZ)(H_2O)]_n$(3), $[Co(3-NPA)(TBZ)(H_2O)]_n$(4) (3-$NPAH_2$ = 3-nitrophthalic acid), have been hydrothermally synthesized through the reaction of 3-nitrophthalic acid with divalent transition-metal salts in the presence of N-donor ancillary coligand (TBZ = thiabendazole). As a result of various coordination modes of the versatile 3-$NPAH_2$ and the coligand TBZ, these complexes exhibit structural diversity. X-ray structure analysis reveals that 1 and 2 are 0D molecular rings, while 3 and 4 are one-dimensional (1D) infinite chain polymers. And the weak O-H${\cdots}$O hydrogen bonds and C-H${\cdots}$O nonclassical hydrogen bonds as well as ${\pi}-{\pi}$ stacking also play important roles in affecting the final structure where complexes 1, 3 and 4 have 3D supramolecular architectures, while complex 2 has a 2D supramolecular network. Also, IR spectra, fluorescence properties and thermal decomposition process of complexes 1-4 were investigated.

• 한국응용과학기술학회지
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• 제22권2호
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• pp.123-135
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• 2005

Reaction intermediates PCP/BZA (PBI) and tetramethylene bis(orthophosphate)(TBOP) were synthesized from polycaprolactone (PCP) and benzoic acid (BZA) and from pyrophosphoric acid and 1,4-butanediol, respectively. Benzoic acid modified polyesters containing phosphorus (APTB-S, -10, -15) were synthesized by polycondensation of the prepared PBI (containing 5, 10, 15wt% of benzoic acid), TBOP, adipic acid, and 1,4-butanediol. Network structured PU flame-retardant coatings (APHD) were prepared by curing the synthesized benzoic acid modified polyesters containing phosphorus (APT B - 5 , -10, -15) with hexamethylene diisocyanate (HDI)-timer. From the TGA analysis of APTBs, it was found that the afterglow decreased with the amount of BZA content at the high temperatures. With the introduction of BZA, the film viscosity and film hardness of APHD decreased. With the introduction of caprolactone group, the flexibility, impact resistance, accelerated weathering resistance of APTBs increased. Flame retardancy of the coatings was tested. In a vertical burning method, APHD shows 210$^{\sim}$313 seconds, which indicates that the coatings are good flame-retardant coatings. Moreover, the amount of afterglow and flame retardancy of the coatings are decreased with increasing BZA content.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2007년도 추계학술 발표회
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• pp.187-192
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• 2007

메탄올 분해/합성 반응을 이용한 장거리 열수송 시스템에 대한 경제적 타당성 연구를 조사하였다. 본 연구는 열공급처에서 흡열반응을 이용하여 메탄올을 수소와 일산화탄소로 분해하여 이 반응생성물 가스를 수송관을 이용하여 열수요처로 이송한 후 열수요처에서 일산화탄소와 수소를 메탄으로 합성하며, 이 발열반응에서 발생하는 열을 회수하여 온수로 사용하는 개념이다. 메탄을 분해/합성 반응은 상대적으로 낮은 온도와 낮은 압력 그리고 높은 전화율을 이용한 장거리 열수송 반응의 대표적인 반응이 될 수 있다. 본 연구에서는 열공급처에서 15 km 떨어진 장소에서 1만 가구에 필요한 온수를 공급하기 위한 시스템의 설계 및 경제성을 검토하였다.

• 한국분말재료학회지
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• 제23권6호
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• pp.420-425
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• 2016

N-doped carbon nanofibers as catalysts for oxygen-reduction reactions are synthesized using electrospinning and carbonization. Their morphologies, structures, chemical bonding states, and electrochemical performance are characterized. The optimized N-doped carbon nanofibers exhibit graphitization of carbon nanofibers and an increased nitrogen doping as well as a uniform network structure. In particular, the optimized N-doped carbon nanofibers show outstanding catalytic activity for oxygen-reduction reactions, such as a half-wave potential ($E_{1/2}$) of 0.43 V, kinetic limiting current density of $6.2mAcm^{-2}$, electron reduction pathways (n = 3.1), and excellent long-term stability after 2000 cycles, resulting in a lower $E_{1/2}$ potential degradation of 13 mV. The improvement in the electrochemical performance results from the synergistic effect of the graphitization of carbon nanofibers and the increased amount of nitrogen doping.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2009년도 춘계 종합학술대회 논문집
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• pp.608-613
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• 2009

이 연구는 생물테러리즘을 위기로 인식하고 생물테러리즘을 위기관리별로 어떻게 관리할 것인가에 대한 관리방안을 연구하는데 그 목적이 있다. 9.11 테러 이후 발생한 탄저균 테러는 전 세계에 생물병원체에 의한 공포감을 인식시켜 주었으며, 그 위험성이 강조된 사례이다. 본 연구결과 생물테러리즘 위기는 4단계로 구분하여 관리할 때 완화 및 예방단계에서는 테러리즘의 기준을 정하고, 대비를 하기 위하여 테러관련 법을 제정하고, 조기발견을 위한 감시체계를 확보해야 한다. 대비단계에서는 초동조치팀을 편성하고 교육훈련을 통해 대응하는 요령을 숙달시켜야 하며, 각종 자원을 확보해야 한다. 대응단계에서는 숙달된 초동조치팀이 즉각 투입되어 현장 정리 및 확산을 방지해야 하며, 복구단계에서는 평가체제를 구축하여 조기에 정상적인 생활로 복귀할 수 있도록 조치해야 한다.

• 한국콘텐츠학회논문지
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• 제9권9호
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• pp.235-242
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• 2009

이 연구는 생물테러리즘을 위기로 인식하고 생물테러리즘을 위기관리별로 어떻게 관리할 것인가에 대한 관리방안을 연구하는데 그 목적이 있다. 9.11 테러 이후 발생한 탄저균 테러는 전 세계에 생물병원체에 의한 공포감을 인식시켜 주었으며, 그 위험성이 강조된 사례이다. 본 연구결과 생물테러리즘 위기는 4단계로 구분하여 관리할 때 완화 및 예방단계에서는 테러리즘의 기준을 정하고, 대비를 하기 위하여 테러관련 법을 제정하고, 조기발견을 위한 감시체계를 확보해야 한다. 대비단계에서는 초동조치 팀을 편성하고 교육훈련을 통해 대응하는 요령을 숙달시켜야 하며, 각종 자원을 확보해야 한다. 대응단계에서는 숙달된 초동조치팀이 즉각 투입되어 현장 정리 및 확산을 방지해야 하며, 복구단계에서는 평가체제를 구축하여 조기에 정상적인 생활로 복귀할 수 있도록 조치해야 한다.

• Korean Chemical Engineering Research
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• 제58권4호
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• pp.596-603
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• 2020

본 연구에서는 화학공정 최적화에 사용되는 생산계획최적기법을 도입하여 핵융합 공정에서의 삼중수소 재고량을 최소로 유지하는 수학적 모델을 구축하여 최적 운전 시나리오를 도출하였다. 핵융합 발전을 위한 공정 중 연료주기 공정(fuel cycle)은 반응연료인 중수소와 삼중수소를 저장 하고 공급하는 시스템과 핵융합 반응 배가스로부터 이를 회수 및 분리하는 세부 공정들로 구성되어 있다. 이들 공정들은 삼중수소가 방사성 물질이라는 것을 제외하면 대부분 촉매반응과 분리공정으로 이루어져 화공플랜트에 적용된 기술과 유사한 특성이 많아 화학공정에 사용되는 스케줄링 기법을 통해 최적 운전 시나리오를 도출 가능하다. 본 연구에서는 핵융합로의 다양한 장치의 특성을 반영해서, 펌프내부의 삼중수소량을 최소로 하는 최적 재생주기를 구하고, 구해진 최적 재생주기 결과를 반영하여 후단의 트리튬 플랜트에서의 최적 운전 시나리오를 확인해 보았다. 구축된 모델은 실제 토카막 시나리오에 적용되어 ITER 연료주기 내 공정의 연료흐름 및 밸런스 분석에 활용되었다.

• 한국세라믹학회지
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• 제12권1호
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• pp.16-22
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• 1975

The network structure of a glass is known to be cracked by a chemical reaction, diffusion, and ion exchange of alkali ion, formed at the crack tip of the glass surface, when water is present on the glass surface. Since the durability of glass is reduced, due to the fatigue phenomenon mentioned above, pollution problem of glass goods, especially bottle glass, is becoming acute gradually. A static fatigue phenomenon was studied thermodynamically in this paper, and a mechanism of static fatigue, a quality control, and a method of preventing pollution for the main local glass goods were also investigated. The PH of reacted solution and the quantity of extracted alkali were measured at different conditions such as temperature, reacting time, particle size of a crushed glass sample, and the nature of reacting solution. The enthalpy change was calculated from the Arrhenius equation. The results are given below; 1) The absolute value of enthalpy change for the bottle glass was found to be higher than the for the flat glass. 2) The fatigue phenomenon of a glass was more sensitive to the temperature than to the reacting time. 3) The durability of glass in acid solution is stronger than in alkaline solution. 4) The substance which cracks the network structure of glas is considered the hydroxyl ion.