• 한국포장학회지
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• 제22권3호
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• pp.41-47
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• 2016

This paper provides an overview of kimchi packaging technology, focusing on packaging materials, package design, and active/intelligent packaging technology for kimchi. From a packaging-material standpoint, although various materials have been used to ensure customer satisfaction and convenience, plastic is the most widely used material, in the form of bags, trays, pouches, and rigid containers. Additionally, recent efforts in the kimchi packaging industry have allowed companies to differentiate their products by using different packaging materials and technologies, while simultaneously improving product safety and quality. On the other hand, the biggest problem in kimchi packaging is excess $CO_2$ production, leading to package expansion and leakage. To alleviate this problem, the use of $CO_2$ absorbers, high $CO_2$-permeable films, and degassing valves, in addition to the use of different packaging systems, has been investigated. Active and/or intelligent packaging systems have been developed, to include active functions beyond simply inert, passive containment and protection of the kimchi product. However, most such approaches are not yet adequately effective to be useful on a commercial scale. Therefore, further studies are needed to resolve the limitations of each technology.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.491-495
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• 2004

The industries use polymer materials for many purposes for they have many merits. The costs of these materials take up too great a proportion of the overall cost of products that use these materials as their major material. It is advantage for polymer industries to reduce these costs. The microcellular foaming process was developed in the early 1980s to solve this problem and proved to be quite successful. Microcellular foaming process uses inert gases such as $CO_2$, $N_2$. As these gases solve into polymer matrices, many properties are changed. The microcellular foaming process makes the glass transition temperature of polymers to low, and diminish the residual stress of polymer matrices. Besides, the microcellular foaming process has several merits, impact strength elevation, thermal insulation, noise insulation, and raw material saving etc. This characteristic of microcellular foaming process has influenced by cell morphology. The cell morphology means cell size and cell density. The cell morphology has influenced by many factors. The examples of factor are pressure drop rate, foaming temperature, foaming time, saturation pressure, saturation time etc. Among their factors, pressure drop rate is the most important factor for cell morphology in microcellular foaming injection molding process. This paper describes about the cell morphology change in accordance with the pressure drop rate of microcellular foaming injection molding process.

• 한국주조공학회지
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• 제10권4호
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• pp.316-323
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• 1990

To improve free-cutting property, fine Pb, Bi particles is necessary to be distributed evenly in Al-Cu alloy. The control of added element size and distribution are very difficult because of the insolubility and gravity segregation of Pb, Bi in the matrix. Therefore, in this study, mechanical stirring of the melt, inert gasbubbling, the addition of degasser are used for the fine distribution of Pb, Bi particles. The best distribution are obtained by stirring with 500 rpm for 10min., Ar gas bubbling with 600cc/min for 5min. and degassing with 0.8wt% degasser. As increasing cooling rate, fine grain size and finely dispersed particles were observed. The optimum pouring temperature was $650^{\circ}C$.

• 한국세라믹학회지
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• 제44권1호
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• pp.37-42
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• 2007

The preparation of $TiC_{0.7}N_{0.3}$ powder by SHS in the system of $Ti-TiH_2-C$ ($N_2$ atmosphere) was investigated in this study. In the preparation of $TiC_{0.7}N_{0.3}$ powder, the effect of gas pressure, compositions such as Ti, $TiH_2$, C, and additive in mixture on the reactivity were investigated. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure $TiC_{0.7}N_{0.3}$ was $0.75Ti+0.25TiH_2+0.7C+0.5NaCl$. The $TiC_{0.7}N_{0.3}$ powder synthesized in this condition was a single phase with irregular shape.

• 한국세라믹학회지
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• 제49권1호
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• pp.56-65
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• 2012

Functional materials are often exposed to high temperatures and inherent temperature gradients. These temperature gradients act as thermodynamic driving forces for the diffusion of mobile components. The detailed consequences of thermodiffusion depend on the boundary conditions of the non-isothermal sample: Once the boundaries of the sample are inert and closed for exchange of the mobile components, thermodiffusion leads to their pile-up in the stationary state (the so called Soret effect). Once the system is open for an exchange of the mobile component, chemical diffusion adds to the Soret effect, and stationary non-zero component fluxes are additionally observed in the stationary state. In this review, the essential aspects of thermodiffusion and Soret effect in inorganic functional materials are briefly summarized and our current practical knowledge is reviewed. Major examples include nonstoichiometric binary compounds (oxides and other chalcogenides) and ternary solid solutions. The potential influence of the Soret effect on the long term stability of high temperature thermoelectrics is briefly discussed. Typical Soret coefficients for nonstoichiometric compounds are found to be of the order of (d${\delta}$/dT) ${\approx}$ 1%/K.

• Journal of Welding and Joining
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• 제25권3호
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• pp.28-36
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• 2007

A bulk amorphous NiTiZrSiSn powder produced using an inert gas atomization was sprayed by kinetic spraying process that is basically a solid-state deposition process onto a mild steel substrate. They were successfully overlaid onto the mild steel substrate. In order to evaluate the tribological behavior of the kinetic sprayed NiTiZrSiSn BMG (Bulk Metallic Glass) coatings, a partially crystallized coating and a fully crystallized coating were prepared by the isothermal heat treatments. Tribological behaviors were investigated in view of friction coefficient, hardness and amorphous phase fraction of coating layer. Surface morphologies and depth in the wear tracks were observed and measured by scanning electron microscope and alpha-step. From the examination of the scratch wear track microstructure, transition from the ductile like deformation (micro cutting) to the brittle deformation (micro fracturing) in the scratch groove was observed with the increase of the crystallinity.

• Nuclear Engineering and Technology
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• 제47권5호
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• pp.617-623
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• 2015

$ZrO_2$-based composites reinforced with 6.5 vol.% of carbon foam, carbon fiber, and graphite were fabricated using spark plasma sintering, and characterized using scanning electron microscopy and X-ray diffractometry. Their thermal properties were also investigated. The microstructures of the reinforced composites showed that carbon fiber fully reacted with $ZrO_2$, whereas carbon foam and graphite did not. The carbothermal reaction of carbon fiber had a negative effect on the thermal properties of the reinforced $ZrO_2$ composites because of the formation of zirconium oxycarbide. Meanwhile, the addition of carbon foam had a positive effect, increasing the thermal conductivity from 2.86 to $3.38Wm^{-1}K^{-1}$ at $1,100^{\circ}C$. These findings suggest that the homogenous distribution and chemical stability of reinforcement material affect the thermal properties of $ZrO_2$-based composites.

• 한국세라믹학회지
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• 제43권10호
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• pp.595-600
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• 2006

The preparation of $\beta$-SiAlON powder by SHS in the system of $Si-Al-SiO_2-NH_4F(\beta-Si_3N_4)$ was investigated in this study. In the preparation of SiAlON powder, the effect of gas pressure, compositions such as Si, $NH_4F$, \beta-Si_3N_4$ and additive in mixture on the reactivity were investigated. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure $\beta$-SiAlON was $3Si+Al+2SiO_2+NH_4F$. The $\beta$-SiAlON powder synthesized in this condition was a single phase $\beta$-SiAlON with a rod like morphology.

• Carbon letters
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• 제3권3호
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• pp.127-132
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• 2002

Unidirectional polymer composites were prepared using high-strength carbon fibers as reinforcement and phenolic resin as matrix precursor with keeping fiber volume fraction at 30, 40, 50 and 60% respectively. These composites were carbonized at $1000^{\circ}C$ and graphitised at $2600^{\circ}C$ in the inert atmosphere. The carbonized and graphitised composites were characterized for mechanical properties as well as microstructure. Microscopic studies were carried out of the polished surface of carbonized and graphitised composites after etching by chromic acid, to understand the effect of fiber volume fraction on oxidation at fiber-matrix interface. It is found that the flexural strength in polymer composites increases with fiber volume fraction and so does for the carbonised composites. However, the trend was found to be reversed in graphitised composites. In all the carbonized composites anisotropic region has been observed at fiber-matrix interface which transforms into columnar type microstructure upon graphitisation. The extension of strong and weak columnar type microstructure is function of fiber volume fraction. SEM microscopy of the etched surface of the sample reveal that composites containing 40% fiber volume has minimum oxidation at the interface, revealing a strong interfacial bonding.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.231.1-231.1
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• 2015

Surface energy, being an important material parameter to control its interactions with the other surfaces plays a key role in bio-related application. Carbon films are found very promising due to their characteristics such as wear and corrosion resistant, high hardness, inert, low resistivity and biocompatibility. The present work deals with the deposition of carbon films using unbalanced facing target magnetron sputtering technique. The discharge characteristics were studied using optical emission spectroscopy and correlated with the film properties. Surface energy was investigated through contact angle measurement. The ID/IG ratio as calculated from Raman spectroscopy data increases with the increase in power density due to the higher number of sp2 clusters embedded in the amorphous matrix. The deposited films were smooth and homogeneous as observed by Atomic force microscopy having RMS roughness in the range of 1.74 to 2.25 nm. It is observed that electrical resistivity and surface energy varies in direct proportionality with operating pressure and has inverse relation with power density. The surface energy results clearly exhibited that these films can have promising applications in cell cultivation.