• 폴리머
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• 제28권5호
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• pp.397-403
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• 2004

광개시제를 이용한 UV 조사방법으로 설폰화 PET-g-GMA 극세 이온 교환 섬유를 합성하고 이들의 구조 및 흡착 특성을 확인하였다. PET-g-GMA의 그라프트율은 UV 조사량, 조사시간 및 반응온도가 증가함에 따라 증가하였으며, 최적 합성조건은 UV조사량, 시간, 반응온도가 각각 450 W, 60 min, $40^{\circ}C$이었다. 한편 최대 설폰화율과 이온 교환 용량은 각각 8.12 mmol/g, 3.25 meq/g의 값을 나타내었다. 또한 설폰화 PET-g-GMA 극세 이온 교환 섬유의 인장강도는 반응전 PET 기재의 인장강도보다 그라프트 반응율이 증가함에 따라 약간 낮아지는 경향을 보였다. 설폰화 PET-g-GMA 극세 이온 교환 섬유의 칼슘 이온, 마그네슘 이온에 대한 흡착 시험 결과 마그네슘 이온이 칼슘 이온보다 흡착 파과 시간이 길었으며, 칼슘 이온, 마그네슘 혼합 용액에서 마그네슘의 흡착 파과 시간은 더욱 길어지는 경향을 보였다.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.558-562
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• 2005

Crystallization of SAPO-5 and SAPO-34 molecular sieves with microwave and conventional electric heating of the same gel has been investigated in an alkaline condition using N,N,N’N’tetraethylethylenediamine as a template molecule. SAPO-5 structure can be selectively prepared with microwave heating because of the fast crystallization of the technique. On the other hand, SAPO-34 is the sole product with usual conventional electric heating because SAPO-5 can be gradually transformed into SAPO-34 structure with an increase in crystallization time. This phase selectivity is probably because of the relative stability of the two phases at the reaction conditions (kinetic effect). Crystallization with microwave heating can be suggested as a phase selective synthesis method for relatively unstable materials because of fast crystallization.

• Fisheries and Aquatic Sciences
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• 제5권2호
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• pp.87-96
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• 2002

The physico-chemical properties of fresh milt of marbled sole, Limanda yokohamae, brown sole, Limanda herzensteini, starry flounder, Platichthys stellatus and olive flounder, Paralichthys olivaceus among flatfishes, and the fine structure of their cryopresserved spermatozoa were investigated. The highest concentration of sperm among these four species was $3.60\pm1.35\times10^{10}/mL$ in marbled sole. Osmolality and pH of seminal plasma in four flatfish species were approximately 330 mOsm/kg and 7.6-8.1, respectively. Seminal plasma compositions showed interspecific differences. The sperm heads of marbled sole, brown sole and starry flounder were ellipsoidal and that of olive flounder was round. The numbers of mitochondria of these four species were eight in marbled sole, seven in brown sole and starry flounder, and six in olive flounder. Cross-sectional view of flagellum showed typical 9+ 2 structure in all species. Most of sperms cryopreserved with a proper method had no visible ultrastructural changes after freeze-thawing, compared with the fresh sperm, but in a few cases, swelling of their heads and midpiece regions were observed.

• 한국재료학회지
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• 제4권6호
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• pp.620-625
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• 1994

자자들은 최근 비고용 Cu-Ta계의 기계적 합금화(Mechanical Alloying) 방법을 이용하여 이계에 있어서 비정질상의 형성에 대한 구조적 확인을 중성자 회절과 EXAFS(Extended X-ray Absorption Fine Structure)의 실험결과로 부터 얻었다. Cu-Ta계와 같이 혼합 엔탈피(Heat of Mixing: $\Delta$ Hmix)가 정인계에 있어서 비정질상 형성에 대한 연구는 구조적인 측면 뿐만 아니라. 시료의 전자물성에 대해서도 많은 연구가 되어야만 할 것으로 사료된다. 따라서 본 논문에서는 120시간 MA방법으로 제작한 시료에 대하여 초전도 천이온도 및 X선 광전자분광 실험에서 얻은 가전자대 구조의 전자물성을 측정하고, 그 결과로부터 이종원자 Cu와 Ta간의 결합은 화하결합에 의한 생성임을 확인하였는데, 이들 결과로부터 120시간 MA를 행하여 얻어진 시료는 확실하게 비정질 합금임을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제35권11호
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• pp.3199-3204
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• 2014

Two novel phosphorescent heteroleptic cationic Ir(III) complexes, Ir(bt)2(dmpe) (Ir1) and Ir (bt)2(dppe) (Ir2), where bt is 2-phenylbenzothiazole, dmpe is 1,2-bis(dimethylphosphino)ethane, and dppe is 1,2-bis(diphenyl-phosphino) ethane, were designed and synthesized. Their photophysical and electrochemical properties and the X-ray structure of the Ir1 complex were investigated. The prepared Ir(III) complexes exhibited blue-green emissions at 503-538 nm with vibronic fine structures in dichloromethane solution and PMMA film, implying that the lowest excited states are dominated by ligand-based $^3{\pi}-{\pi}^*$ transitions. The ${\pi}$-acceptor ability of the diphosphine ancillary ligand leads to blue-shift emission. The room temperature photoluminescent quantum yields (PLQYs) of Ir1 and Ir2 were 52% and 45%, respectively, in dichloromethane solution. These high PLQYs resulted from steric hindrances by the bulky cationic iridium complexes. The crystal structure of Ir1 was determined by X-ray crystallography, which revealed that central iridium adopted a distorted octahedral structure coordinated with two bt ligands (N^C) and one dmpe ligand (P^P) showing cis C-C and trans N-N dispositions. The bent nature of the dmpe ligand resulted in a relatively wide bite angle of $83.83^{\circ}$ of P-Ir-P.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1973-1975
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• 2010

The electronic and adsorption structure of o-phthalaldehyde (OPA) on the H-Si(100) surface was investigated by using Near Edge X-ray Fine Structure (NEXAFS) and high resolution photoemission spectroscopy (HRPES). We confirmed that the OPA grown on the H-Si(100) surface showed good dependency with about 60 degree tilting angle using NEXAFS and a single O 1s peak by using HRPES. Hydrogen atom passivated on the Si(100) surface was found to be a seed for making one dimensional organic line that uses a chain reaction as the H-Si(100) surface was compared with the hydrogen free Si(100) surface.

• 한국분말재료학회지
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• 제18권2호
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• pp.129-134
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• 2011

Herein, macroporous carbon materials were readily prepared by carbonization of cured body of resorcinol and formaldehyde using poly(methyl methacrylate) colloid microspheres which were employed as the template in the gelation of resorcinol with formaldehyde. The gel in the water was solvent exchanged with methanol and the wet gel was dried. After carbonization of the template-gel composite at $800^{\circ}C$, it was found that pores were left corresponding to the size of the template, yielding carbon materials with a fine porous structure with enlarged surface area and significant porosity. Properties of the carbon foams including the structure, morphology, thermal stability, and porosity were investigated. Finally, it was concluded that the method using polymer colloids as the template provided a facile route to prepare carbon foams.

• Bulletin of the Korean Chemical Society
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• 제18권10호
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• pp.1082-1085
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• 1997

The Near-Edge X-ray Absorption Fine Structure (NEXAFS) technique and Differential Scanning Calorimetry (DSC) were utilized to investigate the reaction of CH4 and O2 on the MoO3/SiO2 catalyst. The NEXAFS results showed that the stoichiometry of the molybdenum oxide catalyst supported on silica was MoO3. MoO3 was reduced to MoO2 when the catalyst was exposed to CH4 at 773 K. NEXAFS results confirm that lattice oxygen is directly related to the process of CH4 oxidation which takes place on the surface of MoO3/SiO2 catalysts. DSC results show that the structure of MoO3 changes around 573 K and this structural change seems to improve the migration of oxygen in the lattice.

• Advances in nano research
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• 제13권5호
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• pp.437-451
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• 2022

Synthesis approaches usually affect the physical and chemical properties of ferrites. This helps ferrite materials to design them for desired applications. Some of these methods are mechanical milling, ultrasonic method, micro-emulsion, co-precipitation, thermal decomposition, hydrothermal, microwave-assisted, sol-gel, etc. These methods are extensively reviewed by taking example of ZnFe₂O₄. These methods also affect the microstructure and local structure of ferrite which ultimately affect the physical and chemical properties of ferrites. Various spectroscopic techniques such as Raman spectroscopy, Fourier Transform Infrared spectroscopy, Ultra Violet-Visible spectroscopy, Mossbauer spectroscopy, extended x-ray absorption fine structure, and electron paramagnetic resonance are found helpful to reveal this information. Hence, the basic principle and the usefulness of these techniques to find out appropriate information in ZnFe₂O₄ nanoparticles is elaborated in this review.

• 대한화학회지
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• 제48권6호
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• pp.623-628
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• 2004

빠른 교반 조건에서 구조주형화합물인 TEAOH(Tetraethyl ammonium hydroxide)를 이용하여 제올라이트 SUZ-4를 성공적으로 합성하였다. 교반속도 250 rpm 이상에서 결정성의 제올라이트 SUZ-4를 얻을 수 있었다. 이것은 교반이 재현성있는 합성에 결정적인 역할을 한다는 것을 의미한다. 사용한 물의 양$(H_2O/Al_2O_3)$의 차이에 의하여 SUZ-4 결정형태 조절이 가능하였다. XRD, BET 및 암모니아 TPD에 의해 SUZ-4의 물리화학적 성질 및 증기처리에 의한 열적 안정성이 조사되었다.