• Carbon letters
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• 제10권2호
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• pp.97-100
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• 2009

In this work, effects of carbon matrix on sliding friction and wear behavior of four kinds of C/C have been investigated against 40 Cr steel ring mate. Composite A with rough lamination carbon matrix (RL) shows the highest volume loss and coefficient of friction, while composite D with smooth lamination/resin carbon matrix (SL/RC) shows the lowest volume loss. The worn surface of composite A appears smooth, whereas that of composite C with smooth lamination carbon (SL) appears rough. The worn surface of composite D appears smooth under low load but rough under high load. Atomic force microscope images show that the size of wear particles on the worn surface is also dependent on the carbon matrix.

• 한국신뢰성학회지:신뢰성응용연구
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• 제9권1호
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• pp.47-58
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• 2009

In this paper, an accelerated life test procedure for a vacuum cleaner motor is proposed. We investigate the failure mechanism of the motor and select some accelerating factors and determine the orifice size as a key accelerating factor. Three stress levels of orifice size are tested and the failure data with censored data are analyzed. The modified accelerating test will reduce the test time in design phase by using the accelerating factor.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.85-86
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• 2007

As the manufacturing capacity needs for large size LCD TV shifts very fast into next generation, equipment manufactures face more challenges in development of the systems which can accommodate productivity, reliability and high process quality requirements from the panel makers. AKT committed to continue its contribution to the growth of the LCD market by providing excellent PECVD products. The cost containment and performance improvement are key challenges for large size processing equipment development and this presentation discusses various challenges and AKT's solutions in developing large size PECVD equipment beyond Gen. 8.

• The Journal of Advanced Prosthodontics
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• 제7권3호
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• pp.214-223
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• 2015

PURPOSE. To measure the surface loss of dental restorative zirconia and the short-term bond strength between an indirect composite resin (ICR) and zirconia ceramic after various sandblasting processes. MATERIALS AND METHODS. Three hundred zirconia bars were randomly divided into 25 groups according to the type of sandblasting performed with pressures of 0.1, 0.2, 0.4 and 0.6 MPa, sandblasting times of 7, 14 and 21 seconds, and alumina powder sizes of 50 and $110{\mu}m$. The control group did not receive sandblasting. The volume loss and height loss on zirconia surface after sandblasting and the shear bond strength (SBS) between the sandblasted zirconia and ICR after 24-h immersion were measured for each group using multivariate analysis of variance (ANOVA) and Least Significance Difference (LSD) test (${\alpha}$=.05). After sandblasting, the failure modes of the ICR/zirconia surfaces were observed using scanning electron microscopy. RESULTS. The volume loss and height loss were increased with higher sandblasting pressure and longer sandblasting treatment, but they decreased with larger powder size. SBS was significantly increased by increasing the sandblasting time from 7 seconds to 14 seconds and from 14 seconds to 21 seconds, as well as increasing the size of alumina powder from $50{\mu}m$ to $110{\mu}m$. SBS was significantly increased from 0.1 MPa to 0.2 MPa according to the size of alumina powder. However, the SBSs were not significantly different with the sandblasting pressure of 0.2, 0.4 and 0.6 MPa. The possibilities of the combination of both adhesive failure and cohesive failure within the ICR were higher with the increases in bonding strength. CONCLUSION. Based on the findings of this study, sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of $110{\mu}m$ is recommended for dental applications to improve the bonding between zirconia core and ICR.

• 한국통신학회논문지
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• 제35권5C호
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• pp.445-453
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• 2010

연산 과부하로 인해 대부분의 연구에서는 무선센서네트워크에서 공개키 암호방식의 사용은 힘들다고 여겨져 왔다. 하지만 최근의 일부 연구에서는 키 사이즈, 데이터 사이즈, 연산 시간, 전력 소비 등이 다른 공개키 암호들에 비해 적은 공개키 암호방식을 무선센서네트워크에 적용할 수 있다는 결과가 있다. NTRU 암호방식은 무선센서네트워크에서 사용될 수 있는 공개키 암호방식 중의 하나로 꼽힌다. 하지만 실제로 무선센서네트워크에 적용할 수 있는 NTRU에 기반한 효율적인 키 교환 스킴은 많지 않다. 이 논문에서는 무선센서네트워크에서 사용할 수 있는 NTRU에 기반한 효율적인 키 교환 스킴을 제안한다.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.397-400
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• 2014

Size- and shape-controlled monodisperse wurtzite structured CdS nanorods have been successfully synthesized using a facile solution-based colloidal method. Depending on the control of injection/growth temperatures and the variation of Cd-to-S molar ratios, the morphology of the CdS nanocrystals (NCs) can be adjusted into bullet-like, rod-like, and dot-like shapes. X-ray diffraction (XRD), transition electron microscopy (TEM), and absorption spectroscopy were used to characterize the structure, morphology, and optical properties of as-synthesized CdS NCs. It was found that uniform CdS nanorods could be successfully synthesized when the injection and growth temperatures were very high (> $360^{\circ}C$). The aspect ratios of different shaped (bullet-like or rod-like) CdS NCs could be controlled by simply adjusting the molar ratios between Cd and S.

• 한국컴퓨터정보학회논문지
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• 제13권2호
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• pp.167-175
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• 2008

최근 컴퓨터의 발전을 통해 무선 센서 네트워크 분야가 발전되고 있지만 많은 응용분야에서 보안의 중요성이 증대되고 있다. 특히, 무선 네트워크에서 동작되는 노드의 안전한 통신을 위해서도 보안 메커니즘이나 보안 프로토콜 개발이 필요하다. 이 논문에서는 네트워크에 존재하는 모든 노드가 네트워크 크기에 부합되는 독립된 키들을 소유하면서 노드간 안전한 통신을 보장할 수 있도록 비밀키 방법과 ECC 알고리즘을 조합한 사전 키 분배 방법을 제안한다. 제안된 기법은 노드 캡처에 대해서 탄력적으로 동작하기 때문에 데이터 융합과 집합에 적합하며 네트워크상에 존재하는 타협된 노드들의 탐지를 위해 디지털 시그너처 기능을 적용함으로써 노드간 안전성 문제를 해결하고 있다. 시뮬레이션에서는 제안 기법에서 사용되는 파라미터들의 처리 시간을 평가하여 ECC 키 길이가 증가하더라도 제안 기법이 효율적임을 평가하고 있다.

• 한국IT서비스학회지
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• 제19권1호
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• pp.145-158
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• 2020

With the development and widespread application of online shopping, the number of online consumers has increased. With one click of a mouse, people can buy anything they want without going out and have it sent right to the doors. As consumers benefit from online shopping, people are becoming more concerned about protecting their privacy. In the group buying scenario described in our paper, online shopping was regarded as intra-group communication. To protect the sensitive information of consumers, the polynomial-based encryption key sharing method (Piao et al., 2013; Piao and Kim, 2018) can be applied to online shopping communication. In this paper, we analyze security problems by using a polynomial-based scheme in the following ways : First, in Kamal's attack, they said it does not provide perfect forward and backward secrecy when the members leave or join the group because the secret key can be broken in polynomial time. Second, for simultaneous equations, the leaving node will compute the new secret key if it can be confirmed that the updated new polynomial is recomputed. Third, using Newton's method, attackers can successively find better approximations to the roots of a function. Fourth, the Berlekamp Algorithm can factor polynomials over finite fields and solve the root of the polynomial. Fifth, for a brute-force attack, if the key size is small, brute force can be used to find the root of the polynomial, we need to make a key with appropriately large size to prevent brute force attacks. According to these analyses, we finally recommend the use of a relatively reasonable hash-based mechanism that solves all of the possible security problems and is the most suitable mechanism for our application. The study of adequate and suitable protective methods of consumer security will have academic significance and provide the practical implications.

• Journal of Microbiology and Biotechnology
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• 제26권7호
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• pp.1320-1332
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• 2016

Light hydrocarbons accumulated in subsurface soil by long-term microseepage could favor the anomalous growth of indigenous hydrocarbon-oxidizing microorganisms, which could be crucial indicators of underlying petroleum reservoirs. Here, Illumina MiSeq sequencing of the 16S rRNA gene was conducted to determine the bacterial community structures in soil samples collected from three typical oil and gas fields at different locations in China. Incubation with n-butane at the laboratory scale was performed to confirm the presence of "universal microbes" in light-hydrocarbon microseepage ecosystems. The results indicated significantly higher bacterial diversity in next-to-well samples compared with background samples at two of the three sites, which were notably different to oil-contaminated environments. Variation partitioning analysis showed that the bacterial community structures above the oil and gas fields at the scale of the present study were shaped mainly by environmental parameters, and geographic location was able to explain only 7.05% of the variation independently. The linear discriminant analysis effect size method revealed that the oil and gas fields significantly favored the growth of Mycobacterium, Flavobacterium, and Pseudomonas, as well as other related bacteria. The relative abundance of Mycobacterium and Pseudomonas increased notably after n-butane cultivation, which highlighted their potential as biomarkers of underlying oil deposits. This work contributes to a broader perspective on the bacterial community structures shaped by long-term light-hydrocarbon microseepage and proposes relatively universal indicators, providing an additional resource for the improvement of microbial prospecting of oil and gas.

• International Journal of Industrial Entomology and Biomaterials
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• 제5권1호
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• pp.135-139
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• 2002

By means of correlation analysis and path coefficient analysis, 18 characteristics of 325 conserved silkworm races were studied for the selecting efficiency on main silk quality characteristics. The result showed that selecting lines with heavier cocoon weight are beneficial to raise the weight of have. Choosing strains with higher cocoon shell percentage, longer filament length and better reelability percentage is good for increasing non-broken filament length. Selecting lines with medium daily weight of have produced in the fifth instar, medium cocoon shell percentage and simultaneously selecting heavier cocoon shell weight are favorable to promote reelability percentage. Choosing strains with heavier cocoon weight, higher cocoon shell percentage, heavier daily weight of bave produced in the fifth instar and heavier weight of bave but shorter filament length may hopefully breed out a race with thick filament size. And selecting strains with heavier weight of have and fine filament size are beneficial to increase filament length. Selecting lines with higher cocoon shell percentage and heavier weight of bave are favorable to raise raw silk percentage of cocoon. There are no significant direct or indirect correlation coefficient between viability and major characteristics of silk quality. It is, therefore, feasible to breed a silkworm race with excellent vitality and good silk quality as well.