• Journal of Microbiology and Biotechnology
• /
• v.14 no.2
• /
• pp.337-343
• /
• 2004

A bacterial strain concurrently producing extracellular chitosanase and chitinase was isolated from soil and identified as a member of the $\beta$-subgroup of Proteobacteria through its 16S rRNA analysis and some biochemical analyses. The newly discovered strain, named as KNU3, had 99% homology of its 16S rRNA sequence with chitinolytic $\beta$-Proteobacterium CTE108. Strain KNU3 produced 34 kDa of chitosanase in addition to two chitinases of 68 kDa and 30 kDa, respectively. The purified chitosanase protein (ChoK) showed activity toward soluble, colloidal, and glycol chitosan, but did not exhibit any activity toward colloidal chitin. The optimum pH and temperature of ChoK were 6.0 and $70^{\circ}C$, respectively. The chitosanase was stable in the pH 4.0 to 8.0 range at $70^{\circ}C$, while enzyme activity was relatively stable at below $45^{\circ}C$. MALDI-TOF MS and N-terminal amino acid sequence analyses indicated that ChoK protein is related to chitosanases from Matsuebacter sp. and Sphingobacterium multivorum. HPLC analysis of chitosan lysates revealed that glucosamine tetramers and hexamers were the major products of hydrolysis.

• Journal of Korean Society for Quality Management
• /
• v.38 no.4
• /
• pp.521-530
• /
• 2010

Global regulatory pressures relating climate change and environmental responsibility are asking companies to find out the best way for sustaining their continuous business growths. It could be known that inadequate management for environmental issues are bad for business, negatively affecting brand image, causing unnecessary losses and costs for environmental preservation. For this reason, environmentally conscious green business growth has been recognized as an essential requirement for a company to stay in business. Many companies are looking for green business opportunities of improving their environmental and financial results, and struggling with how green fits into their business. In this paper, the Green Six Sigma, an environmentally conscious Six Sigma methodology, is presented as a way to find solutions for green growths. The Six Sigma is known as a disciplined, data-driven approach and methodology for achieving world-class performance in any process from manufacturing to transactional. In chronological order, the Six Sigma has been evolved from Motorola's quality-oriented methodology to GE's cost-oriented lean approach, and is being evolved and developed as an environment-oriented green growth approach. There is no doubt that the Green Six Sigma, as an engine of green growth, is a power tool for achieving competitive business performance and reducing the impact on the environment.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.3_1spc
• /
• pp.504-508
• /
• 2013

This paper describes in detail the life prediction models and simulations of thermal fatigue under different mold compounds and chip sizes for wafer-level embedded SiP. Three-dimensional finite element models are built to simulate the viscoplastic behaviors for various mold compounds and chip sizes. In particular, the bonding parts between a mold and silicon nitride (Si3N4) are carefully modeled, and the strain distributions are studied. Three different chip sizes are used, and the effects of the mold compounds are observed. Through the numerical studies, it is found that type-C, which has a relatively lower Young's modulus and higher CTE, has a better fatigue life than the other mold compounds. In addition, the $4{\times}4$ chip has a shorter life than the $6{\times}6$ and $8{\times}8$ chips.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.6
• /
• pp.124-138
• /
• 1998

Particles reinforced MMCs have many advantages over monolithic metals including a higher specific modulus, higher specific strength, better properties at elevated temperatures and better wear resistance. SiC$_p$/A16061 composites have good results in its mechanical properties. This work investigates SiC$_p$/A16061 composites in the microscopic view and compares the analytical results with the experimental ones. The discrepancy of the material properties between the reinforced particle, SiC$_p$, and the matrix material, A16061 appears to be so significant. Especially the coefficient of thermal expansion(CTE) of A16061 is 5 times larger than that of SiC$_p$. Thermal residual stress in MMCs is induced at high temperatures. The shape of particle is various but the theoretical model is not able to consider the nonuniform shape. Particle distribution is not homogeneous in experimental specimen. However, it is assumed to be homogeneous in simulation model. The shapes of particles are assumed to be not only perfect global but hexahedral shapes. The types of particle distribution are two - simple cubic array(SC array) and face-centered cubic array(FCC array).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.4
• /
• pp.2407-2414
• /
• 2015

This paper presents analytical expressions for the determination of out of plane thermo-elastic properties for conventional laminated composite plates. The approach follows that commonly accepted for in-plane properties. Results over a variety of lay-ups reveals that it is poor assumption to use transverse tape lamina properties to represent out of plane laminate properties for laminates with more than 10% plies oriented off-axis($90^{\circ}$) from uniaxial or for laminates with angle plies of $15^{\circ}$ or greater.

• Journal of the Semiconductor & Display Technology
• /
• v.15 no.4
• /
• pp.1-9
• /
• 2016

The warpage on mobile phone camera packages occurs due to the CTE(Coefficient of Thermal Expansion) mismatch between a thin silicon die and a substrate. The warpage in the optical instruments such as camera module has an effect on the field curvature, which is one of the factors degrading the optical performance and the product yield. In this paper, we studied the effect of die bonding epoxy on the package and optical performance of mobile phone camera packages. We calculated the warpages of camera module packages by using a finite element analysis, and their shapes were in good agreement showing parabolic curvature. We also measured the warpages and through-focus MTF of camera module specimens with experiments. The warpage was improved on an epoxy with low elastic modulus at both finite element analysis and experiment results, and the MTF performance increased accordingly. The results show that die bonding epoxy affects the warpage generated on the image sensor during the packaging process, and this warpage eventually affects the optical performance associated with the field curvature.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.11 s.242
• /
• pp.1480-1487
• /
• 2005

Metal matrix composites(MMCs) have been rapidly becoming one of the strongest candidates for structural materials fur many high temperature application. However, among the various high temperature environments in which metal matrix composites was applied, thermal shock is known to cause significant degradation in most MMC system. Due to the appreciable difference in coefficient of thermal expansion(CTE) between reinforcement and metal matrix, internal stresses are generated following temperature changes. Infernal stresses affect degradation of mechanical properties of MMC by causing microscopic damage in interface and matrix during thermal cycling. Therefore, the nondestructive evaluation on thermal shock damage behavior of SiC/A16061 composite has been carried out using ultrasonics. For this study, SiC fiber reinforced metal matrix composite specimens fabricated by a squeeze casting technique were thermally cycled in the temperature range 298$\~$673 K up to 1000cyc1es. Three point bending test was conducted to investigate the efffct of thermal shock damage on mechanical properties. The relationship between thermal shock damage behavior and the propagation characteristics of surface wave and SH-ultrasonic wave was discussed by considering the result of SEM observation of fracture surface.

• Journal of the Microelectronics and Packaging Society
• /
• v.8 no.3
• /
• pp.31-36
• /
• 2001

Dielectric material which is suitably designed for the application of the high-temperature electrostatic chucks(HTESCS) has been developed. Electrical resistivities and dielectric constants of the dielectric layer satisfy the demands for the proper operation of HTESC, and coefficient of thermal expansion(CTE) of the dielectric material matches well that of the bottom insulator so that it secures stable structure. In order to minimize particle contaminations, borosilicate glass(BSG) is selected as a bonding layer between dielectric layer and bottom insulator, and silver is used as a electrode. BSG is solidly bonded between upper dielectric and bottom insulator, and no diffusions or reactions are observed among silver electrode, dielectric, and glass layers. The chucking characteristics of the fabricated HTESC are found to be superior to those of the commercialized one.

• Journal of the Korean Ceramic Society
• /
• v.43 no.12 s.295
• /
• pp.865-871
• /
• 2006

In order to examine and compare the characteristics of two vitrified forms (AG8W1 and DG2) simulated for the operation of a commercial vitrification facility being constructed in Ulchin nuclear power plant, the vitrified forms were cooled by the natural cooling and annealing methods respectively. And the Product Consistency Test (PCT), compressive strength, thermal conductivity, specific heat, phase stability, softening point and Coefficient of Thermal Expansion (CTE) of the vitrified farms were experimented. Consequently, it was shown that there were no significant differences on the physiochemical properties of the vitrified forms performed the natural cooling and annealing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.340-341
• /
• 2008

본 논문에서는 미세 패턴을 구현하기 위해 폴리머 소재의 조성에 따른 공정의 영향에 대해서 연구를 하였다. 제작된 본딩 필름은 난연계 에폭시수지와 고내열 특성을 위해서 경화제 조화 성분 폴리머를 이용하였다. 또한, CTE 값을 향상하기 위해서 필러로서 SiO2 분말을 이용하였다. 조성물은 혼합하여 슬러리를 만들고, 테입 캐스터를 이용하여 필름을 제작하였다. 제작된 필름은 150 및 160도의 온도에서 가열 가압하여 경화하였다. 제작된 수지는 유전율 3.2의 유전율과 loss tan 6값이 0.015값을 나타내었다. 또한 제작된 본딩 필름의 조화특성 연구를 위해서 경화조건, 스웰링 조건, 디스미어 시간에 따른공정 변화의 영향에 대해 고찰하였으며 제작된 시편의 조도는 SEM으로 관찰하여 조화성분 함량에 따른 최적 조건을 선정하였다.