• 융합보안논문지
• /
• 제8권4호
• /
• pp.41-49
• /
• 2008

VoIP 서비스는 아날로그인 음성 신호를 디지털 신호로 변환한 후 패킷으로 구성하여 사용자에게 음성정보를 전달해주는 서비스로 기존의 음성전화 서비스에 비해 요금이 저렴하고 확장성이 뛰어난 장점을 가지고 있다. 그러나 VoIP 서비스는 기존의 음성전화 서비스(PSTN)에 비해서 열악한 통화품질과 보안측면의 취약성을 포함한 시스템 구조를 갖는다. 이와 같은 문제점을 보완하기 위해 TLS 서비스를 도입함으로서 보안성을 높였지만, 실제적인 시스템에서는 QoS 문제점이 발생하므로 보안적인 측면과 QoS를 동시에 만족시킬 수 있는 VoIP 보안 시스템 개발이 필요하다. 본 논문에서는 기존 VoIP 세션 설정단계에 AA 서버를 추가하여 사용자의 접근에 따른 차등 서비스를 제공함으로서 보안과 사용자에 따른 서비스를 제공할 수 있는 사용자 권한 인증 VoIP 시스템을 제안한다. 본 논문에서 제안한 시스템은 TLS 기술을 추가한 시스템보다 빠른 QoS를 제공하면서 비슷한 보안성을 제공한다는 이점을 가지고 있다. 또한 사용자별 다양한 부가서비스를 제공할 수 있다.

• Reproductive and Developmental Biology
• /
• 제36권3호
• /
• pp.183-188
• /
• 2012

The bovine fatty acid binding protein 4 and 5 (FABP4 and 5) is a major positional and physiological candidate gene for the bovine marbling and carcass weight. The aim of this study was to evaluate the association between economic traits of Korean cattle (Hanwoo) and genetic variation in fatty acid binding protein 4 and 5 (FABP4 and 5) genes within carcass/meat quality traits and the before/after of fatting in breed Hanwoo. Here, we characterized the nucleotide polymorphism of FABP4 and 5 in 86 cattle. We were detected the variability of three types (GG, AG, and AA) by PCR, and economic traits were analyzed by the mixed regression model implemented in the ASReml program. As the result of statistical and supersonic analysis, FABP4 gene was highly showed significant effect (p<0.006) on marbling score (MS), in contrast FABP5 gene was lowed (p<0.084) on MS before fatting. But, FABP4 gene was highly showed significant effect (p<0.0054) on MS, in contrast FABP5 gene lowest (p<0.0899) on MS in the after of fatting. Compare to supersonic result before fatting in FABP4 gene, it was detected type GG: (p<7.18), AG: (p<8.50), and AA: (p<10.50) (n=50), showed type GG: (p<4.88), AG: (p<2.33), and AA: (p<0.00) after weed out (n=20). Futhermore, it was detected type GG: (p<9.30), AG: (p<7.95), and AA: (p<7.40) (n=50) before fatting in the FABP5 gene. It was shown type GG: (p<2.67), AG: (p<3.50), and AA: (p<5.00) after weed out (n=50). Our results indicate that FABP4 and 5 gene transcription is regulated by the environment of feeding and management, and suggest that feeding and management could be potential key in determining FABP4 and 5 genes transcription for carcass/meat quality traits in breed Hanwoo.

• 한국식품과학회지
• /
• 제21권6호
• /
• pp.788-794
• /
• 1989

감자의 vitamin C함량에 대한 blanching온도 및 조리방법의 영향을 알아보고 저장기간이 다른 감자에 대한 영향도 조사하였다. 또한 조리방법이 다른 감자에 대한 관능 평가를 비교 검토하였다. 감자의 vitamin C 함량에 대한 blanching온도의 영향은 원료감자의 경우 40에서는 감자내 잔여 AA 및 TAA 함량이 가장 높았으며 $50-65^{\circ}C$에서는 급격히 감소하였다. 한편 산화된 AA 함량 및 가수분해된 DHA 함량은 $50-65^{\circ}C$에서 급격히 증가하였다. 그리고 조리수로 용출된 AA및 TAA 함량은 온도 증가에 따라 계속 증가하였다. 저장한 감자의 경우 vitamin C 함량에 대한 blanching 온도의 영향은 원료감자의 경우와 유사한 경향을 나타내었다. 한편 blanching 과정 중 vitamin C의 손실은 AA의 산화반응을 통한 가수분해 반응에 의하므로 원료감자를 1-4주간 저장함에 따른 잔여 TAA, 용출된 TAA 및 가수분해된 DHA함량의 변화를 살펴보면 $40^{\circ}C$에서 잔여 TAA는 85-71.2%로서 지속적인 감소를 나타내었고 조리수로 용출된 TAA 함량은 2.9-7.7%로서 증가하였으며 가수분해 된 DHA함량은 5.5-18.2%로서 꾸준히 증가하였다. $65^{\circ}C$에서는 가수분해 된 DHA 함량은 저장기간에 따라 43.8-47.4%로 감소하였다. 저장기간이 다른 감자의 vitamin C 함량에 대한 조리방법의 영향은 원료감자의 경우 감자내 잔여 TAA 함량은 pressure cooking> microwave cooking> boiling의 순서로 감소하였으며 TAA 잔존율은 각각 58.6%, 53.2%, 28.2%이었다. boiling 및 microwave cooking시 조리수로 용출된 TAA함량은 각각 49.5%와 36.4%이었으며 가수분해 된 DHA함량은 각각 22.3%와 4.2%이었다. 한편 저장한 감자의 경우 잔여 TAA 함량에 대한 조리방법의 영향은 원료감자와 유사한 경향을 보였으며 각 조리방법에 따른 잔여 TAA 함량은 저장기간에 따라 감소하는 경향을 보였다. 그러나 용출된 TAA와 가수분해 된 DHA는 장기간에 따라 지속적인 증감은 나타내지 않았다. 조리방법에 따른 감자의 관능평가 결과는 견고성은 대조감자> pressure cooking, boiling>microwave cooking순서로 감소하였으며 씹힘성은 대조감자> pressure cooking> boiling, microwave cooking순서로 감소하였다. 접착성은 pressure cooking> microwave cooking, boiling4>대조감자의 순서로 감소하였으며 종합적인 기호도는 pressure cooking>microwave cooking>boiling>대조감자의 순서로 감소하였다(p<0.05).

• 한국광물학회지
• /
• 제9권1호
• /
• pp.1-6
• /
• 1996

Woolastonite from Susan occurs as intercalations in limestone beds of Lower Paleozoic Joseon Supergroup. It is a thermal metamorphic product of impure limestone. Electron microprobe analysis shows that it is considerably pure wollastonite. It has triclinic cell with a=7.932$\AA$, b=7.328$\AA$, c=7.069$\AA$, $\alpha$=89.995$^{\circ}$, $\beta$=$95.255^{\circ}$, and $ \Upsilon=103.367^{\circ}$.Dissolution behaviors of wollastonite have been studied conducting three different dissolution experiments; two different reactions with HC1 (one batch and one re-initialization experiment) and one traction with distilled water. In the batch type powder wollastonite-HCl reaction, pH of solution rapidly increases in the early stage and then its rate of increase slows down to reach plateau resulting in parabolic relationship with time. It is represented by the early rapid rise and fall in pH giving a sharp pH-edge and succeeding slow rise in the re-initialization experiment. The early rapid rise in pH is due to the rapid sorption of H- in solution to oxygens on the reactive surface of wollastonite and the fall in pH means that all reactive surface sites are occupied by H- ions and no more H- adsorption occurs. The slow rise in pH following the pH- edge is due to the dissolution of wollastonite as evidenced by the correlation of pH variation and cation concentration. Dissolution of powder wollastonite in HCl shows linear trend with time. Si is dissolved predominantly over Ca at a constant rate. Ca is dissolved predominantly in the very early stage. Dissolution rate of coarse-grained wollastonite fragments in distilled water is parabolic with times howing a rapid reaction in the early stage and a slow reaction in the advanced stage. The Ca/Si ratio in solution is high in the case of coarse-grained wollastonite fragment as compared with powder wollastonite. The coarse-grained wollastonite fragment-water (acid) reaction resulted in the solution with an elevated constant pH value (alkaline) giving an important significance on the environmental view point.

• Advances in materials Research
• /
• 제1권2호
• /
• pp.147-160
• /
• 2012

In the present study, diffusion bonding was carried out between AZ31B magnesium and AA2024 aluminium in the temperature range of $405^{\circ}C$ to $475^{\circ}C$ for 15 min to 85 min and 5MPa to 20 MPa uniaxial loads was applied. Interface quality of the joints was assessed by microhardness and shear testing. Also, the bonding interfaces were analyzed by means of optical microscopy, scanning electron microscopy, energy dispersive spectrometer and XRD. The maximum bonding and shear strength was obtained at $440^{\circ}C$, 12 MPa and 70 min. The maximum hardness values were obtained from the area next to the interface in magnesium side of the joint. The hardness values were found to decrease with increasing distance from the interface in magnesium side while it remained constant in aluminium side. It was seen that the diffusion transition zone near the interface consists of various phases of $MgAl_2O_4$, $Mg_2SiO_4$ and $Al_2SiO_5$.

• 한국응용과학기술학회지
• /
• 제26권2호
• /
• pp.224-231
• /
• 2009

Techniques measuring Maxwell displacement current (MDC) and LB films surface measuring technique have been applied to the study of monolayers of polyamic acid containing azobenzene. MDCs was generated from monolayers on the water surface by monolayer compression and expansion. It was generated when the area per molecule was about $103{\AA}^2\;and\;78{\AA}^2$ just before the initial rise of the surface pressure during the 1st and 2nd mixed monolayer compressions cycle, respectively. It was the maximum of MDCs appeared at the molecular area just before the initial rise of surface pressure in compression cycles, and we have found that the increase of aggregations causes the noticeable increase of the surface roughness.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1995년도 추계학술대회 논문집
• /
• pp.113-117
• /
• 1995

The mechanism of the displacement current generation for stimulation transmit observed in the present displacement current measurement and theoretically analysed. The orientational change of molecules in monolayers was discussed on the basis of the Maxwell-displacement-current obtained. Maxwell displacement current was generated from monolayers on a water surface by monolayerr compression, and it measuring technique has been applied to the study of monolayers of Dipalmitoylphosphatidyl choline (L-${\alpha}$-DPPC). Finally, We measured that differential thermal analysis(DTA) of sample. Displacement current was generated when the area per molecule about 180${\AA}$$^2$in low pressure, and it was generated when the area per molecule about 110${\AA}$$^2$in high pressure. A result of DTA was showed that temperature at 124.6$^{\circ}C$.

• Journal of Magnetics
• /
• 제15권3호
• /
• pp.99-102
• /
• 2010

We present the fractal properties of the magnetic domain walls in $(5-{\AA}\;Co_{90}Fe_{10}/10-{\AA}\;Pt)_n$ multilayer films with perpendicular magnetic anisotropy for the number of repeats n (1 to 5). In these films, the magnetization reversed due to the domain wall propagation throughout the films with rare nucleations. As n increased, it was observed that the jaggedness of the domain walls increased noticeably, which is possibly due to the accumulation of irregularities at the layer interfaces. The jaggedness of the domain walls was analyzed in terms of the fractal dimension by use of the ruler method, and it was revealed that the fractal dimension significantly changed from $1.0{\pm}0.002$ to $1.3{\pm}0.05$ as n increased from 1 to 5.

• 대한가정학회지
• /
• 제5권1호
• /
• pp.815-825
• /
• 1966

Many synthetic antioxidants are now used to prevent the oxidation of oils and fats. Among the synthetic and tioxidants, it was known that those of HQ(Hydroquinone), BHA(Butyl hydroxyanisole), IG(isoamyl gallate), and NDGA(Nordihydro guaiaretic acid) are most efficient as the antioxidizing agent. In this work, Degree of antioxidation was investigated on the some such antioxidans BHA, CI(citric acid), AA(Ascoric acid) for several kinds of oils and fats which are most available in Korea by determining Acid value and Iodine Value. The results of experiments were as follows 1. The decreasing order of antioxidizing action by acid value is BHA, AA, CA. 2. The order of antioxidizing action by Iodine value is almost same as the case of Acid Value. 3. It is effective to add the antioxidants to kep oils and fat. 4. Oxidation is accelerated by standing oils and fats after boiling in the from fry pan. 5. Sesame oil is little oxidized without antioxidant.

• Journal of Korean Vacuum Science & Technology
• /
• 제3권1호
• /
• pp.16-23
• /
• 1999

Deposition of parylene (PA) films has been explored at substrate temperatures below 2$0^{\circ}C$ and pressures below 4 torr. The film thickness was measured using AFM and the film thickness measured was 3,500-12,000$\AA$ and the growth rate was 20-70$\AA$/min. T도 dielectric constant of the deposited PA films was found to be 2.66 and the dielectric strength was in excess of 2$\times$105V/cm. The growth rate became a maximum at a precursor decomposition temperature of $600^{\circ}C$. It was found that the growth rate decreased with increasing substrate temperature, whereas it increased with increasing pressure. At a precursor decomposition temperature of 75$0^{\circ}C$ or at a deposition pressure above 1 Torr the film surface became rough due to particle formation in the gas phase. The condensation of a p-xylylene monomer on the substrate surface turned out to be a rate-limiting step in the growth of the PA films.