• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2311-2316
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• 2014

Conformations and vibrational frequencies of the racemic (2RS,3RS)-5-amino-3-(4-phenylpiperazin-1-yl)-1,2,3,4-tetrahydronaphthalen-2-ol-(I) [(2RS,3RS)-(I)], a precursor of benzovesamicol analogues, have been carried out using various DFT methods (M06-2X, B3LYP, B3PW91, PBEPBE, LSDA, and B3P86) with basis sets of 6-31G(d), 6-31+G(d,p), 6-311+G(d,p), 6-311++G(d,p), cc-pVTZ, and TZVP. The LSDA/6-31G(d) level of theory shows the best performance in reproducing the X-ray powder structure. However, the PBEPBE/cc-pVTZ level of theory is the best method to predict the vibrational frequencies of (2RS,3RS)-(I). The potential energy surfaces of racemic pairs (2RS,3RS)-(I) and -(II) are obtained at the LSDA/6-31G(d) level of theory in the gas phase and in water. The results indicate that (2RS,3RS)-(I) are more stable by ~0.75 kcal/mol in energy than (2RS,3RS)-(II) in water, whereas conformer AIIg and BIIg are more stable by ~0.04 kcal/mol than AIg in gas phase. In particular, the hydrogen bond distances between the N of piperazine and the OH of tetrahydronaphthalen become longer in gas, compared with those in the water phase. Vibrational frequencies calculated at the PBEPBE/cc-pVTZ level of theory in the gas phase are larger than those in water, whereas their intensities in the gas phase are weaker than those in water.

• Archives of Pharmacal Research
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• 제29권12호
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• pp.1164-1170
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• 2006

A triptolide-lysozyme (TP-LZM) conjugate was synthesized to achieve renal specific delivery and to reduce the side effects of triptolide. Triptolide was coupled to lysozyme through succinic via an ester bond with an average coupling degree of 1 mol triptolide per 1 mol lysozyme. The lysozyme can specifically accumulate in the proximal tubular cells of the kidney, making it a potential carrier for targeting drugs to the kidney. The structure of triptolide succinate (TPS) was confirmed by IR, $^{1}H-NMR$, MS and UV. The concentrations of triptolide in various samples were determined by reversed-phase high-performance liquid chromatography (HPLC). In this study, the physicochemical and stability profiles of TP-LZM under various conditions were investgated the stability and releasing profiles of triptolide-lysozyme (TP-LZM) under various conditions. In vitro release trails showed triptolide-lysozyme was relatively stable in plasma (less than 30% of free triptolide released) and could release triptolide quickly in lysosome (more than 80% of free triptolide released) at $37^{\circ}C$ for 24 h. In addition, the biological activities of the conjugate on normal rat kidney proximal tubular cells (NRK52E) were also tested. The conjugate can effectively reduce NO production in the medium of NRK52E induced by lipopolysaccharide (LPS) but with much lower toxicity. These studies suggest the possibility to promote curative effect and reduce its extra-renal toxicity of triptolide by TP-LZM conjugate.

• Journal of Ginseng Research
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• 제34권2호
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• pp.113-121
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• 2010

The fresh ginseng roots were extracted with aqueous methanol, and the obtained extracts were partitioned using ethyl acetate, n-butanol, and water, successively. The repeated silica gel and octadecyl silica gel column chromatogaraphy for n-butanol fraction afforded four diol ginseng saponins, ginsenosides $Rb_1$, $Rb_2$, $R_c$, and Rd. The physicochemical, spectroscopic, and chromatographic characteristics of these ginsenosides were measured and compared with those reported in the literature. Some of the peak assignments in previously published $^1H$- and $^{13}C$-nuclear magnetic resonance (NMR) spectra were inaccurate. This study employed two-dimensional NMR experiments, including $^1H-^1H$ correlation spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond connectivity, to determine exact peak assignments.

• 콘크리트학회논문집
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• 제25권5호
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• pp.565-572
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• 2013

CBPC(chemically-bonded phosphate ceramic) 바인더는 사소 MgO와 인산의 강력한 산-염기 반응을 이용한 초속경 보수재료로서, 시멘트와는 달리 CaO의 함량을 10% 이하로 줄인 재료이다. 이번 실험에서는 CBPC 바인더에 천연광물 및 산업부산물로 이뤄진 6가지 충전재들을 첨가하고 물리적 성능 및 수화 반응을 관찰하였다. 실리카퓸을 첨가한시편이 압축강도 및 동탄성계수가 상대적으로 높았고, 특히 장기강도 면에서 뚜렷한 증가율을 보였다. 또한 XRD 분석을 통해 실리카퓸을 첨가한 시편에서 마그네슘의 수화물인 M-S-H gel and $MgCO_3$ 피크를 관찰 할 수 있었다. 칼슘 성분이 다량 포함된 충전재를 넣은 시편의 경우 강도 및 내구성 면에서 좋지 않은 결과를 낳은 것으로 보아, 칼슘과 마그네슘 수화물은 서로 화학적으로 결합하지 않으므로 섞지 않는 것이 좋다는 결론을 도출했다. 결과적으로 MgO를 기반으로 하는 모르타르에는 순수하게 실리카 성분으로만 이루어진 실리카 흄과 같은 충전재가 알맞은 것으로 나타났다.

• 한국도로학회논문집
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• 제17권3호
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• pp.77-83
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• 2015

PURPOSES : In this study, a fracture-based finite element (FE) model is proposed to evaluate the fracture behavior of fiber-reinforced asphalt (FRA) concrete under various interface conditions. METHODS : A fracture-based FE model was developed to simulate a double-edge notched tension (DENT) test. A cohesive zone model (CZM) and linear viscoelastic model were implemented to model the fracture behavior and viscous behavior of the FRA concrete, respectively. Three models were developed to characterize the behavior of interfacial bonding between the fiber reinforcement and surrounding materials. In the first model, the fracture property of the asphalt concrete was modified to study the effect of fiber reinforcement. In the second model, spring elements were used to simulated the fiber reinforcement. In the third method, bar and spring elements, based on a nonlinear bond-slip model, were used to simulate the fiber reinforcement and interfacial bonding conditions. The performance of the FRA in resisting crack development under various interfacial conditions was evaluated. RESULTS : The elastic modulus of the fibers was not sensitive to the behavior of the FRA in the DENT test before crack initiation. After crack development, the fracture resistance of the FRA was found to have enhanced considerably as the elastic modulus of the fibers increased from 450 MPa to 900 MPa. When the adhesion between the fibers and asphalt concrete was sufficiently high, the fiber reinforcement was effective. It means that the interfacial bonding conditions affect the fracture resistance of the FRA significantly. CONCLUSIONS : The bar/spring element models were more effective in representing the local behavior of the fibers and interfacial bonding than the fracture energy approach. The reinforcement effect is more significant after crack initiation, as the fibers can be pulled out sufficiently. Both the elastic modulus of the fiber reinforcement and the interfacial bonding were significant in controlling crack development in the FRA.

• 한국강구조학회 논문집
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• 제16권5호통권72호
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• pp.575-586
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• 2004

본 논문은 새롭게 개발된 춤이 깊은 데크 플레이트(이하 Deep Deck) 및 비대칭 H형강 하부플랜지에 플레이트를 용접한 비대칭 철골보로 구성된 매립형(슬림플로어) 합성보의 웨브면에 개구부를 가진 유공 합성보의 휨성능에 관한 실험적 연구이다. 실험은 철골보 춤(250mm, 300mm), 개구부의 위치 및 가력조건에 따라 5개의 유공 합성보에 대한 단순지지 휨실험 수행하였다. 실험결과, 매립형 유공합성보는 전단연결재를 사용하지 않고도 콘크리트의 면내 부착력에 의해 충분한 합성작용을 하는 것으로 나타났고, 개구부 주변이 콘크리트에 의해 구속되어 개구부의 보강없이 충분한 구조적 성능을 발휘할 수 있음을 확인하였다.

• 펄프종이기술
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• 제29권1호
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• pp.7-12
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• 1997

This study was intended to investigate the proper shape and size of calcium carbonate for the improvement of paper properties and its end use performance. We loaded calcium carbonate of various shapes and size in the handsheet and measured their physical and optical properties. Results obtained from the study are summarized as follows : 1. Due to different particle shapes and sizes, precipitated calcium carbonate (PCC) contributed greater to bulk improvement than ground calcium carbonate (GCC). Scalenohedral form of PCC produced the bulkiest sheet, GCC made the sheet bulkier as average particle size increases. 2. Tensile strength increased as average particle size was increasing. GCC kept tensile strength more effectively than PCC. The effect of particle size on tensile strength was much more pronounced as filler addition level was increasing. 3. Over the average particle size of 6.99$\mu$m, GCC gave much higher burst strength and internal bond than PCC did. In the filler levels of 20% and 30%, GCC by using bigger size fillers showed 50~100% improvement in some cases than PCC at the same filler content. 4. Tear strength increased as average particle size was increasing. At the filler level of 30%, PCC decreased tear greatly. 5. Over the average particle size of 13.56$\mu$m, GCC kept bending stiffness greater than PCC. Due to its shape, Scalenohedral form of PCC showed higher stiffness than others at the same particle size. 6. Cubic and acicular form of PCC improved light scattering coefficient very effectively. Light scattering coefficient of GCC decreased as average particle size increased. 7. Both of particle shape and size of filler were important factor in developing optical properties and bending stiffness. Particle size was the only important factor in developing other strength properties

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.207-207
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• 2011

Amorphous transparent oxide semiconductors (a-TOS) have been widely studied for many optoelectronic devices such as AM-OLED (active-matrix organic light emitting diodes). Recently, Nomura et al. demonstrated high performance amorphous IGZO (In-Ga-Zn-O) TFTs.1 Despite the amorphous structure, due to the conduction band minimum (CBM) that made of spherically extended s-orbitals of the constituent metals, an a-IGZO TFT shows high mobility.2,3 But IGZO films contain high cost rare metals. Therefore, we need to investigate the alternatives. Because Aluminum has a high bond enthalpy with oxygen atom and Alumina has a high lattice energy, we try to replace Gallium with Aluminum that is high reserve low cost material. In this study, we focused on the electrical properties of IZO:Al thin films as a channel layer of TFTs. IZO:Al were deposited on unheated non-alkali glass substrates (5 cm ${\times}$ 5 cm) by magnetron co-sputtering system with two cathodes equipped with IZO target and Al target, respectively. The sintered ceramic IZO disc (3 inch ${\phi}$, 5 mm t) and metal Al target (3 inch ${\phi}$, 5 mm t) are used for deposition. The O2 gas was used as the reactive gas to control carrier concentration and mobility. Deposition was carried out under various sputtering conditions to investigate the effect of sputtering process on the characteristics of IZO:Al thin films. Correlation between sputtering factors and electronic properties of the film will be discussed in detail.

• 한국구조물진단유지관리공학회 논문집
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• 제15권2호
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• pp.107-115
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• 2011

본 연구는 부착재료의 변화 및 동결융해에 따른 FRP-콘크리트구조물 경계면의 거동을 조사하였다. 실험 시 고려된 연구변수로는 부착경계면의 부착강도, 경계면 유효부착길이 등을 조사하였다. 경계면 부착재료에 따른 거동변화 실험체의 경우 FRP-구조물 부착경계면에 사용되는 에폭시의 종류를 각각 3가지로 분류하며 FRP-콘크리트간 다양한 부착길이를 고려하여 시편을 제작하였으며 동결융해에 따른 경계면 거동조사의 경우 0 cycle에서 300cycle까지 계속적으로 증가되는 주기에 대하여 실험체들을 제작, 장기거동 부착실험을 수행하였다. 본 실험결과, 적용 부착재료의 종류에 따라 최대 유효부착길이는 5~7% 차이가 있었으며 동결융해 주기증가에 따른 최대부착하중 및 유효부착길이의 경우 초기에 나타난 급격한 거동변화 이후 상대적으로 불규칙한 변화를 장기적으로 나타내었다.

• 한국구조물진단유지관리공학회 논문집
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• 제18권3호
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• pp.153-159
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• 2014

본 연구에서는 고경질 도막재로 PET 필름을 접합하는 시공방법에 있어서 PET 필름의 표면처리 조건 및 겹침이음 길이에 따른 접합특성 및 내구특성을 검토하였는데, 그 결과 무처리 보다 코로나 방전 처리에 의해 접촉각, 접합 인장강도, 벗김저항성이 개선되었다. 특히 시험체 E (코로나 방전+프라이머+강접접착제+폴리에스터 부직포)에서 가장 높은 것으로 나타났으며, 특히 겹침 이음길이 15mm 이상일 때 16주간 장기간 열화처리에도 안정적인 접합성능을 확보하는 것으로 나타나 방수재료로서 수밀성을 확보할 것으로 판단된다.