양극산화된 탄소섬유/에폭시 복합재료의 크랙저항 특성

박수진,오진석,서동학 한국화학공학회 2004 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.42 No.1

본 실험에서는, 양극산화 처리된 탄소섬유의 표면 변화가 탄소섬유 강화 에폭시 복합재료의 크랙저항 특성에 미치는 영향에 대하여 고찰하였다. 탄소섬유의 표면처리 전후 표면특성 변화는 산-염기도, FTR-IR, XPS 그리고 접촉각 측정을 통하여 알아보았고, 복합재료의 크랙저항 특성은 임계에너지 방출 속도 Ⅰ(critical energy rate, G_(Ic))와 임계에너지 방출 속도 Ⅱ(critical energy rate mode Ⅱ, G_(IIc))의 두 가지 방법을 통하여 고찰하였다. 실험결과, 탄소섬유 표면의 표면 산도와 O_(IS)/C_(IS) 비율이 증가하였는데, 이는 탄소섬유의 산성관능기와 표면자유에너지의 극성요소 증가에 기인하는 것으로 판단된다. 복합재료의 G_(Ic)그리고 G_(IIc)같은 기계적 계면성질은 탄소섬유의 양극산화로 향상되어졌는데, 이는 산성관능기들의 증가에 따른 탄소섬유와 매트릭스와의 계면 결합력의 증가에 기인하는 것으로 판단된다. Anodic oxidation on the surfaces of carbon fibers was carried out to enhance the mechanical interfacial properties of carbon fibers-reinforced epoxy matrix composites. And the surface characteristics of untreated and treated carbon fibers were studied by FT-IR, XPS, and contact angle measurements after modifications. Crack resistance of the composites was investigated using by two types of testing method, namely critical energy release rate mode Ⅰ(G_(ⅠC)) and mode Ⅱ(G_(ⅡC)). The O_(IS)/C_(IS) ratio of the carbon fibers was increased after anodic treatment, due to the introductions of the oxygen-containing functional groups, or the specific components of surface free energy of the carbon fibers. It was found that the mechanical properties at interfaces, including G_(ⅠC) and G_(ⅡC) of the composites had been improved by the oxidation, which could probably be attributed to the increase of the degree of adhesion at interfaces between fibers and resin matrix in the composite system.

표면처리된 탄화규소의 첨가가 탄소섬유 강화 복합재료의 열안정성 및 기계적 특성에 미치는 영향

박수진,오진석,서동학 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.5

본 연구에서는 표면처리에 따른 탄화규소(SiC)의 표면특성변화가 탄소섬유 강화 복합재료의 열안정성과 기계적 물성에 미치는 영향을 조사하였다. 표면처리된 탄화규소의 표면특성은 산·염기도, 접촉각측정 그리고 FT-IR을 통하여 알아보았으며, 열안정성은 TGA를 이용하여 조사하였다. 탄소섬유 강화 복합재료의 기계적물성은 interlaminar shear strength(ILSS) 그리고 critical strain energy release rate mode Ⅱ(G_(IIC))를 통하여 고찰하였다. 실험결과 산 처리된 SiC(A-SiC)와 오존처리된 SiC(0-SiC)는 미처리된 SiC(V-SiC)나 염기 처리된 SiC(B-SiC)에 비하여 산도가 증가하였고, 접촉각 측정 결과, 산성 용액과 오존 표면처리는 극성요소의 증가에 기인하는 SiC의 표면자유에너지를 증가시켰다. ILSS과 G_(IIC) 같은 기계적 계면 성질은 A-SiC와 O-SiC로 향상되어졌는데, 이러한 결과는 좋은 젖음성이 최종 복합재료의 SiC와 에폭시 수지 매트릭스 사이의 계면결합력을 증가시키는 중요한 역할을 하기 때문으로 판단된다. In this work, the effect of chemically wet and dry treatments of SiC was investigated in mechanical interfacial properties of carbon fibers-reinforced composites. The surface properties of Sic were determined by acid/base values, contact angles, and FT-IR analyses. The thermal stabilities of the carbon fibers-reinforced composites were investigated by thermo-gravimetric analysis (TGA). Also, the mechanical interfacial properties of the composites were studied in interlaminar shear strength (ILSS) and critical strain energy release rate mode Ⅱ(G_(ⅡC)) measurements. As a result, the acidically treated SiC (A-Sic) and ozone treated (0-Sic) had higher acid value than that of untreated Sic (V-Sic) or basically treated Sic (B-Sic). According to the contact angle measurements, it was observed that acidic solution and ozone treatments led to an increase of surface free energy of the SIC surfaces, mainly due to the increase of the specific (polar) component. The mechanical interfacial properties of the composites, including ILSS and G_(ⅡC) had been improved in the specimens treated by acidic solutions and ozone gas. These results were explained that good wetting played an iniportant role in improving the degree of adhesion at interfaces between SiC and epoxy resin matrix in a composite system

Al_2O_3를 함유한 Poly(ε-caprolactone)/Poly(ethylene oxide) 마이크로캡슐의 향오일 방출거동

박수진,양영준,이재락,서동학 한국공업화학회 2003 공업화학 Vol.14 No.3

본 실험에서는 소수성의 PCL과 친수성의 PEO의 함량비를 변화시키면서 액증건조법을 이용하여 향오일이 흡착된 Al_2O_3를 심물질로 함유하는 마이크로캡슐을 제조하였다. 또한, Al_2O_3의 화학적 처리가 마이크로캡슐의 향오일 방출거동에 미치는 영향을 고찰해 보았으며, 산-염기 표면처리 용액으로서 30 wt% HCL(Al_2O_3 -HCl)과 30 wt% NaOH(Al_2O_3 -NaOH) 용액을 각각 사용하였다. 처리 전후의 Al_2O_3의 표면 산-염기도는 Boehm 선택 중화법을 이용하여 측정하였다. PEO의 함량에 따른 마이크로캡슐의 형태는 image analyzer와 scanning electron microscope (SEM)을 통하여 관찰하였다. FT-IR 측정을 통하여 심물질이 함입되었음을 확인하였으며, 또한 접촉각 측정을 통하여 표면 자유에너지의 변화를 알아보았다. 그 결과, PCL/PEO 마이크로캡슐의 직경, 표면 자유에너지 그리고 향오일의 방출속도는 PEO의 함량이 증가할수록 증가하였다. 또한 Al_2O_3-HCL을 함유한 PCL 마이크로캡슐의 향오일 방출속도는 감소하였는데, 이는 PCL/PEO 마이크로캡슐의 친수성의 증가와 산-염기 반응에 의해 물리화학적으로 Al_2O_3와 향오일간의 분자간 인력이 증가하였기 때문이라 사료된다. In this work biodegradable polymers of hydrophobic poly(ε-caprolactone) (PCL) and hydrophilic poly(ethylene oxide) (PEO) were prepared in different weight ratios, 100 : 0, 90 : 10, 80 : 20, and 70 : 30, to manufacture the microcapsules containing Al_2O_3 and fragrant oil by an oil-in-water (o/w) emulsion solvent evaporation method. The release behaviors of microcapsules were studied by chemical treatments of Al_2O_3 with 30 wt% HCl and Al_2O_3 with 30 wt% NaOH. The acid and base values were investigated with the Boehm's titration technique. The effect of PEO content on the diameter and shape of microcapsules were observed with image analyzer and scanning electron microscope (SEM). PCL/PEO microcapsules containing flagrant oil were confirmed by FT~IR. The variation of surface free energy of the microcapsules characterized by contact angles was examined in terms of PEO ratio in the blending system. As a result, it was found that the diameter, surface free energy, and fragrant oil release rate of PCL/PEO microcapsules increased with increasing the PEO ratio. However, the fragrant oil release rate of PCL microcapsules containing Al_2O_3-HCl decreased. These results were mainly due to the increased hydrophilicity of the microcapsules or the acid-base interfacial interactions between Al_2O_3-HCL and fragrant oil.

Stereoelective Polymerization of Racenic cis -β- lactams using L - amino Acids as Initiators

Dong Hack Suh,Sam Kwon Choi 한국고분자학회 1983 한국고분자학회 학술대회 연구논문 초록집 Vol.1983 No.10

특별강연 - 고분자공업분과 : 곁가지 이미드기를 가진 신고분자 합성

서동학 ( Dong Hack Suh ) 한국공업화학회 1997 한국공업화학회 연구논문 초록집 Vol.1990 No.3

Cilostazol eliminates adverse smoking outcome in patients with drug-eluting stent implantation.

Kim, Hack-Lyoung,Suh, Jung-Won,Lee, Seung-Pyo,Kang, Hyun-Jae,Koo, Bon-Kwon,Cho, Young-Seok,Youn, Tae-Jin,Chae, In-Ho,Choi, Dong-Ju,Rha, Seung-Woon,Bae, Jang-Ho,Kwon, Taek-Geun,Bae, Jang-Whan,Cho, Myeo Japanese Circulation Society 2014 CIRCULATION JOURNAL Vol.78 No.6

<P>The present study investigated whether cilostazol can eliminate adverse smoking outcome after percutaneous coronary intervention (PCI).</P>

Patterned grafting of acrylic acid onto polymer substrates

Kim, Dong-Ki,Choi, You Mee,Jung, Chan-Hee,Kwon, Ho-Je,Choi, Jae-Hak,Nho, Young-Chang,Suh, Dong-Hack,Ganesan, Ramakrishnan,Kim, Jin-Baek John Wiley Sons, Ltd. 2009 Polymers for advanced technologies Vol.20 No.3

<P>Polyethylene films were irradiated through a mask with high-energy argon ions to activate the surface for grafting. Acrylic acid was graft polymerized onto the irradiated region of the polyethylene surface. The grafted surface was characterized by using FT-IR and XPS. Patterned grafting of acrylic acid on the polyethylene surface was finally confirmed by a fluorescence labeling method. Copyright © 2008 John Wiley & Sons, Ltd.</P>

A Simple Method for Reconstruction of the Temporalis Muscle Using Contourable Strut Plate after Pterional Craniotomy: Introduction of the Surgical Techniques and Analysis of Its Efficacy

Jin-Hack Park,Yoon-Soo Lee,Sang-Jun Suh,Jeong-Ho Lee,Kee-Young Ryu,Dong-Gee Kang 대한뇌혈관외과학회 2015 Journal of Cerebrovascular and Endovascular Neuros Vol.17 No.2

Objective:Pterional craniotomy (PC) using myocutaneous (MC) flap is a simple and efficient technique; however, due to subsequent inferior displacement (ID) of the temporalis muscle, it can cause postoperative deformities of the muscle such as depression along the inferior margin of the temporal line of the frontal bone (DTL) and muscular protrusion at the inferior portion of the temporal fossa (PITF). Herein, we introduce a simple method for reconstruction of the temporalis muscle using a contourable strut plate (CSP) and evaluate its efficacy. Materials and Methods:Patients at follow-ups between January 2014 and October 2014 after PCs were enrolled in this study. Their postoperative deformities of the temporalis muscle including ID, DTL, and PITF were evaluated. These PC cases using MC flap were classified according to two groups; one with conventional technique without CSP (MC Only) and another with reconstruction of the temporalis muscle using CSP (MC + CSP). Statistical analyses were performed for comparison between the two groups. Results:Lower incidences of ID of the muscle (p < 0.001), DTL (p < 0.001), and PITF (p = 0.001) were observed in the MC + CSP than in the MC Only group. The incidence of acceptable outcome was markedly higher in the MC + CSP group (p < 0.001). ID was regarded as a causative factor for DTL and PITF (p < 0.001 in both). Conclusion:Reconstruction of the temporalis muscle using CSP after MC flap is a simple and efficient technique, which provides an outstanding outcome in terms of anatomical restoration of the temporalis muscle.

Entropy, enthalpy, and gibbs free energy variations of ¹³³Cs via CO₂-activated carbon filter and ferric ferrocyanide hybrid composites

Lee, Joon Hyuk,Suh, Dong Hack Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.11

The addition of ferric ferrocyanide (Prussian blue; PB) to adsorbents could enhance the adsorption performance of ¹³³Cs. Toward this goal, we present a heterogeneously integrated carbonaceous material platform consisting of PB in direct contact with CO₂-activated carbon filters (PB-CACF). The resulted sample retains 24.39% more PB than vice versa probed by the ultraviolet-visible spectrometer. We leverage this effect to capture ¹³³Cs in the aqueous environment via the increase in ionic strength and micropores. We note that the amount of PB was likely to be the key factor for ¹³³Cs adsorption compared with specific surface characteristics. The revealed adsorption capacity of PB-CACF was 21.69% higher than the bare support. The adsorption characteristics were feasible and spontaneous. Positive values of 𝜟H^o and 𝜟S^o show the endothermic nature and increased randomness. Based on the concept of capturing hazardous materials via hazardous materials, our work will be of interest within the relevant academia for collecting radionuclides in a sufficient manner.

In Situ Crosslinked Ionic Gel Polymer Electrolytes for Dye Sensitized Solar Cells

Shim, Hyo-Jin,Kim, Dong-Wook,Lee, Chang-Jin,Kang, Yong-Ku,Suh, Dong-Hack The Polymer Society of Korea 2008 Macromolecular Research Vol.16 No.5

We prepared an ionic gel polymer electrolyte for dye-sensitized solar cells (DSSCs) without leakage problem. Triiodide compound (BTDI) was synthesized by the reaction of benzene tricarbonyl trichloride with diethylene glycol monotosylate and subsequent substitution of tosylate by iodide using NaI. Bisimidazole was prepared by the reaction of imidazole with the triethylene glycol ditosylate under strongly basic condition provided by NaH. BTDI and bisimidazole dissolved in an ionic liquid were injected into the cells and permeated into the $TiO_2$ nanopores. In situ crosslinking was then carried out by heating to form a network structure of poly(imidazolium iodide), thereby converting the ionic liquid electrolytes to a gel or a quasi-solid state. A monomer (BTDI and bisimidazole) concentration in the electrolytes of as low as 30 wt% was sufficient to form a stable gel type electrolyte. The DSSCs based on the gel polymer electrolytes showed a power conversion efficiency of as high as 1.15% with a short circuit current density of $5.69\;mAcm^{-2}$, an open circuit voltage of 0.525 V, and a fill factor of 0.43.