알릴에스터 수지의 경화특성연구

허완수 崇實大學校 生産技術硏究所 1996 論文集 Vol.26 No.2

Synthetic marbles have been developed due to the excellent heat resistance, chemical resistance, good processibility, and uncomparable toughness for many years. Thermoset resin such as unsaturated polyester or poly(methyl methacrylate) has been used and recently allyster resin which can be polymerized using dially monomer and polyol by transesterification reaction shows lot of interests. In this study, the reactivity and curing mechanism has been studied by differential scanning calorimetry followed by the selection of monomer, diol, and curing agent. Diallyl terephthalate and diallyl isophthalate were used as prepolymer and diethylene glycol and 1,3-butane diol were used as allyl monomer. Several curing agents such as dicummyl peroxide, t-butyl peroxybenzoate, t-butyl peroxy-2-ethyl hexanoate, 2-butanone peroxide, or di-t-butyl peroxide have been studied for the optimum curing process. Isothermal and dynamic differential scanning calorimetry(DSC) methods with varying heating rate were utilized and activation energy of 90.3kJ/mol for DCP and 86.6kJ/mol for TBPB were calculated by Kissinger equation. Besides, DCP and TBPB have been found to exhibit good curing results since over 100 C, the decomposition rate of curing agent was vary fast enough ti induce the brittle physical properties.

웹기반 크리프 물성 데이터베이스 개발

허용학,백운봉,이완규,박휘립,정인현 한국산업안전학회 2002 한국안전학회지 Vol.17 No.4

User-friendly-web-based database system for searching creep property data was developed. This system includes about 38000 creep data for 270 different materials including low carbon steel, stainless steel and alloy steel. Data on creep rupture, creep deformation, creep crack growth and creeping materials can be searched through this system. Retrieved data is displayed in numeric form and also presented in graphical form for visualizing the data. Furthermore, the creep rupture data is designed to be fitted to a regression equation of logarithmic stress using time-temperature parameter(TTP). The degree of the regression equation, orthogonal polynomials, was determined using analysis of variance.

Characterization of a Constitutive β-Lactamase from a Pseudomonas aeruginosa

유진홍,허동호,최정현,김양리,신원식,강문원 대한화학요법학회 1996 대한화학요법학회지 Vol.14 No.2

Objective : We analyzed some physicochermical chracteristics of a constitutive β-lactamase from a clinical isolate of a Pseudomonas aeruginosa which resistant to various β-lactams except imipenem and susceptible to aminoglycosides the proportion of its contribution to such resistance profile. Method : 1. Antimicrobial susceptibility test was done by the broth dilution method. 2. In hibition profile was done using EDTA, HgCl₂ and p-chloromercuribenzoate (pCMB). We also measured 50% inhibitory concentration(IC??) using β-lactamase inhibitors, such as clavulanic acid, sulbactam. 3. Kinetics study for substrate profile was performed by spectrophotometric assay using crude extracts and various antimicrobial agents. Relative hydropysis rates were determined. 4. The isoelectric point(pI) was determined by isoelectric focusing. The molecular weight was estimated by SDS-polycrylamide gel electrophoresis. Results : 1. The strain was resistant to ceftriaxone, sulperazon, piperacillin, ceftazidime, and aztreonam, while it was susceptible to gontamicin, tobramycin, amikacin and imipenem. 2. The β-lactamase was not inhibited by EDTA, and pCMB, whereas it was inhibited by HgCI₂. The IC?? of clavulanic acid was over 100μM and that of sulbactam was 22μM. 3. The relative maximal hydrolysis rate was calculated by setting V_(max) for cephaloridine at 100. The enzyme hydrolyzed cephalosporins more rapidly than penicillins. 4. The pI was 9.3 by isoelectric focusing. The molecular weight was estimated to be 40kDa. Conclusion : According to its substrate profile, pI and molecular weight, the β-lactamase from a clinical isolate of P. aeruginosa was a cephalosporinase belonging to group 1 in the Bush-Jacoby-Medeiros classification scheme.

Nylon6,6/Polyaniline 전도성 복합체의 제조 및 전기적 성질에 관한 연구

김효용,허양일,이완진 全南大學校 觸媒硏究所 1998 觸媒硏究 論文集 Vol.20 No.-

The conducting composite using polyaniline as a conducting polymer and nylon6,6 as a matrix by blending method was prepared. The m-cresol was used as a solvent in blending. The PANI was protonated using camphorsulfonic acid(CSA) or dodecylbenzenesulfonic acid (DBSA) such as alkylbenzenesulfonic acid. In the conducting composite, DBSA was found to be more superior dopant to CSA and the electrical conductivity was increased with the amount of PANI complex. Also, in the temperature range of -196℃ to 160℃, the electrical conductivity was measured. The temperature dependency for conducting composites varied with the content of PANI complex and followed variable range hopping model. The electric conductivity was increased up to 0.19 S/cm with the amount of PANI complex protonated with DBSA having long alkyl chain.

Staphylococcus aureus와 Coagulase-Negative Staphylococcus Species에 대한 Arbekacin의 시험관내 항균력

위성헌,강진한,허동호,이동건,김상일,김양리,최정현,김종현,유진흥,허재균,신완식,강문원 대한감염학회 2001 감염 Vol.33 No.4

Background : Most strains of methicillin-resistant Staphylococcus aureus (MRSA) now exhibit high-level resistance to various antibiotics, such as β -lactam antibiotics, aminoglycosides, macrolides, tetracyclines and quinolones. Recent reports describing the therapeutic failure of vancomycin for MRSA infections have arisen considerable concerns regarding the emergence of MRSA strains, which will require new therapeutic agents. Arbekacin, an aminoglycoside antibiotic, has antibacterial activity against both gram-positive and gram-negative bacteria and is stable in the presence of aminoglycoside inactivating enzymes produced by S. aureus. In this study, we compared the antibacterial activity of arbekacin with those of vancomycin, gentamicin, and amikacin against Staphylococcus aureus (S. aureus) and coagulase-negative staphylococci (CNS). Methods : For a collection of 549 S. aureus and 251 CNS isolates from three Catholic University Hospitals in Korea, minimum inhibitory concentrations (MICs) of arbekacin, vancomycin, amikacin and gentamicin were determined by agar dilution method using Mueller-Hinton agar according to NCCLS (National Committee for Clinical Laboratory Standards, USA)criteria. Results : Among 549 S. aureus isolates, 278 isolates were MRSA and 271 isolates were methicil sensitive S. aureus (MSSA). MIC50 & MIC90 of arbekacin against 549 S. aureus were 0.5 & 1 ㎍/mL, and MIC50 & MIC90 of vancomycin were 1 & 1 ㎍/mL. MIC of arbekacin against 549 S. aureus isolates ranges from 0.03 to 4 ㎍/mL, and MIC of vancomycin against 549 S. aureus ranges from 0.25 to 2 ㎍/mL. MIC90 of amikacin against 549 S. aureus was 32㎍/mL, and that of gentamicin was 128 ㎍/mL. MICs of amikacin and gentamicin were variable, ranging from 0.125 to 256, and otherwise arbekacin and vancomycin revealed relatively narrow range of MICs. MIC90 of arbekacin against 278 MRSA isolates & 271 MSSA were 1 & 0.5 ㎍/mL, and those of vancomycin against MRSA & MSSA were 1 & 1 ㎍/mL. MIC90 of amikacin against 278 MRSA & 271 MSSA isolates were 32 & 4 ㎍/mL, and that of gentamicin against MRSA & MSSA isolates were 128 & 32 ㎍/mL respectively. Among 251 CNS isolates, 122 isolates were MRCNS and 129 were MSCNS. MICSO & MIC90 of arbekacin against 251 CNS isolates were 0.25 & 2 ㎍/mL, and those of vancomycin were 1 & 2 ㎍/mL. MIC of arbekacin against 251 CNS isolates ranges from 0.015 to 32 ㎍/mL, and that of vancomycin isolates ranges from 0.25 to 2 ㎍/mL, MIC90 of arbekacin against 122 MRCNS & 129 MSCNS isolates were 2&0.3 ㎍/ML, and those of vancomycin were 2&s ㎍/ML. MIC90 of amikacin against 251 CNS isolates was 32 ㎍/ML, and that of gentamicin was 128 ㎍/ML for CNS. MIC90 of amikacin against 122 MRCNS & 129 MSCNS isolates were 128 & 8㎍/mL, and those of gentamicin ere 256 & 32 ㎍/mL. Conclusion : Considering above results, arbekacin can be useful agent against most strains of MRSA and MRCMS, which exhibit high-level resistance to amikacin and gentamicin. (Korea J Infect Dis 33:254~260, 2001)

MoSi_2기 복합재료의 소결온도에 따른 미끄럼마모 특성

이광영,박원조,허선철,김형진,박성호 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-

Molybdenum disilicide(MoSi_2) is considered to be a promising high temperature material for turbojet anhypersonic engines in aerospace and various industrial applications, because of a high melting point(2030℃),adequate density(6.3g/cm^3) and an excellent oxidation resistance. Mosi2 powder was evaluated from the variation of fabricating such as preparation temperature 1250℃, 1350℃ and 1500℃ respectively. Abrasion tester used a pin-on-disk type and a Si3N4 ceramic ball which used as machine structural materials. The test condition apply to load of 8kgf at 7.5rpm for 6 hours and the effect of hardness is also discussed. As a result of the tests, the friction coefficient was decreased with sintered MoSi_2 of increasing temperature but the function coefficient did not vary much for all specimens at all temperatures.

SCM에 의해 제조된 금속기복합재료의 파괴인성 및 미끄럼마모 특성

이광영,박원조,허선철,신동인 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-

AC4CH-based metal matrix composites with All_8B_40_33w reinforcement have been produced using squeeze casting method Metal matrix composite that is produced from matrix material AC4CH and inorganic binders Al_2O_3 and TiO_2 are added to the metal matrix composite for strength so binding among the whisker can take place. In this paper, an investigation was performed on frictional abrasion and the fracture toughness of AC4CH alloy reinforced with 20wt% aluminum borate whisker which contained a Al_20_3, TiO_2. The test of fracture toughness was using CT(half-size) specimen of thickness 12.5mm, width 25mm(ASTM E1820). To test for tribo a pin-on-disk machine and lubricant is used without paraffine 8.2CST at room temperature.

X-선 회절법에 의한 소결광내의 칼슘페라이트 생성에 미치는 Al_2O_3, SiO_2 및 MgO의 영향

朴埈賢,趙兪貞,尹晟燮,許完旭,金亨順 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.7

In order to elucidate the fundamental aspects of the minerals formation processes during sintering, the Fe_2O_3-CaO-Al_2O_3-SiO_2 system and the effect of MgO on synthesized iron ore sinter were studied by image analysis and X-ray diffraction method. Most existed calcium ferrite was identified to be a solid solution of CaO·2Fe_2O_3 with a small amount of solubility of Al_2O_3 and SiO_2. With an increase of the content of Al_2O_3 in the system, the amount of calcium ferrite was increased. On the other hand, the amount of calcium ferrite was decreased, and the amount of hematite was increased with increasing the content of SiO_2. Crystal structure of calcium ferrite with Al_2O_3 and SiO_2 was changed from monoclinic to triclinic as well as the unit cell volume shrank with fixing Al_2O_3 and increasing SiO_2. With increasing the content of MgO(1∼3 wt%), the amount of magnetite was increased and hematite was decreased but calcium ferrite was not changed.

Fish Materials as Potent Attractants for the Male of Bean Bug, Riptortus clavatus

Wan Huh,Hye Soon Huh,박정규 한국응용곤충학회 2005 Journal of Asia-Pacific Entomology Vol.8 No.4

Fish materials were tested for their attractiveness to the bean bug, Riptortus clavatus (Thunberg) (Heteroptera: Alydidae) in a soybean field. Fish materials’ volatiles evoked male-specific responses in attractiveness. Fish materials such as mackerel, hairtail, and gizzard shad attracted significantly higher number of males than control, but they were not attractive to females. The attractiveness of MeOH extract of mackerel to R. clavatus males was not different from 10 live males and aggregation pheromone traps of R. clavatus. Further studies are needed to identify volatile compound(s) from fish smell responsible for the attraction of R. clavatus males.

Fish Materials as Potent Attractants for the Male of Bean Bug, Riptortus clavatus

Huh, Wan,Huh, Hye-Soon,Park, Chung-Gyoo Korean Society of Applied Entomology 2005 Journal of Asia-Pacific Entomology Vol.8 No.4

Fish materials were tested for their attractiveness to the bean bug, Riptortus clavatus (Thunberg) (Heteroptera: Alydidae) in a soybean field. Fish materials' volatiles evoked male-specific responses in attractiveness. Fish materials such as mackerel, hairtail, and gizzard shad attracted significantly higher number of males than control, but they were not attractive to females. The attractiveness of MeOH extract of mackerel to R. clavatus males was not different from 10 live males and aggregation pheromone traps of R. clavatus. Further studies are needed to identify volatile compound(5) from fish smell responsible for the attraction of R. clavatus males.