• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.10
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• pp.1011-1019
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• 2015

Insulated-gate bipolar transistors (IGBTs) are the predominantly used power semiconductors for high-current applications, and are used in trains, airplanes, electrical, and hybrid vehicles. IGBT power modules generate a considerable amount of heat from the dissipation of electric power. This heat generation causes several reliability problems and deteriorates the performances of the IGBT devices. Therefore, thermal management is critical for IGBT modules. In particular, realizing a proper thermal design for which the device temperature does not exceed a specified limit has been a key factor in developing IGBT modules. In this study, we investigate the thermal behavior of the 1200 A, 3.3 kV IGBT module package using finite-element numerical simulation. In order to minimize the temperature of IGBT devices, we analyze the effects of various packaging materials and different thickness values on the thermal characteristics of IGBT modules, and we also perform a design-of-experiment (DOE) optimization

• Journal of the Korean Applied Science and Technology
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• v.32 no.1
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• pp.85-92
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• 2015

The 50 mole% HCl doped polyaniline(PAni) was synthesized by polymerization of aniline in the presence of hydrochloric acid and ammonium persulfate(APS) as dopant and oxidant, respectively. Then, conducting biodegradable cellulose acetate composite films were also prepared with PAni in acetone to find their applicability to antistatic packaging materials. The tensile strength of PCA05 film with 5 wt% of PAni was decreased by 27% from $377.1kg_f/cm^2$ for CA film itself to $275.2kg_f/cm^2$. Elongation was also decreased from 7.65% to 4.35%. Surface registance of $7.0{\times}10^9{\Omega}/sq$ could be achieved for the PCA containing 5 wt% of PAni. Therefore, this PCA05 film can be applied to antistatic package film for electronic board. In addition, decomposition temperature of these PCA films obtained by thermogravimetric analysis(TGA) was decreased with the amount of PAni in PCA films, and the final weight of char was directly proportional to PAni contents. From this thermal result we can calculate the content of PAni in unknown PCA films.

• Preventive Nutrition and Food Science
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• v.11 no.4
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• pp.348-357
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• 2006

Nano is a unit that designates a billionth; accordingly nanotechnology could be described as the study and applications of the unique characteristics and phenomena of nanometer size materials. Applications of nanotechnology fall into two categories (one is top-down and the other is bottom-up). Currently, most products are the results of the top-down approach. Nanofoods have distinct functional characteristics stemming from the size, mass, chemical combinations, electrolytic features, magnetic properties of food sources at the nano level and which can be applied for safe absorption and delivery into the body. The greatest advantage of nanofood is that it permits the efficient use of small quantities of nutritional elements by increasing digestive absorption ability and by delivering natural elements without any change in their original characteristics. On the other hand, there are still unsolved problems, such as questions about safety and introduction of harmful material. The demand for new commercial food products is increasing, and commercial food producers are gradually combining nanotechnology and traditional food preparation methods. Nanofoods will improve our eating habits remarkably in the future. Tomorrow we will design nanofoods by shaping molecules and atoms. It will have a big impact on the food and food-processing industries. The future belongs to new products and new processes with the goals of customizing and personalizing consumer products. Nanotechnology is expected to be applied to not only foods themselves, but also to food packaging, production, safety, processing and storage. Also, it is believed that nanotechnology will be applied tracking finished products back to production facilities and even to specific processing equipment in those facilities. The aim of this study is the introduction of technology, applications, products, markets, R&D, and perspectives of nanofoods in the food industry.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.2
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• pp.41-45
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• 2013

Extractives of garlic (Allium scorodorpasum) and green pepper (Capsicum annuum L.) were used to prevent and exterminate rice weevils which contaminate stored rice. The extractives exhibited great efficacy against Sitophilus oryzae and Tribolium castaneum by annihilating all the weevils contained in a bottle. Furthermore, kraft paper coated by 5% extractives also displayed good effectiveness against the rice weevils. When rice weevils were stored with rice in a sack made of extractives-coated kraft paper, the number of living insects was sharply decreased according to elapsed time. In particular, 1,4-benzoquinone, which is very harmful to human, was detected from rice contaminated by Sitophilus oryzae and Tribolium castaneum through the analysis of GC/MS.

• Korean journal of food and cookery science
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• v.29 no.2
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• pp.169-175
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• 2013

The purpose of this study was to provide the basic information necessary to efficiently run a coffee shop. It comparatively analyzes the relative importance and satisfaction of side menu selection characteristics through analyses on customer importance-satisfaction when selecting a side menu as well as their usage behavior of the side menu at coffee shops. According to reason price the analysis result on the differences in the coffee shop side menu importance and satisfaction, there was a difference because the importance of selecting a side menu was higher for the attributes of taste, health, packing & appearance, economics and personnel service compared to satisfaction among which the price of a side menu was found to be the top priority for improvement. The significance of coffee shop side menu for the respondents prior to usage as well as their satisfaction after usage was evaluated in order to comparatively analyze the relative importance and achievement of each characteristic through the IPA. The result indicated that the variables positioned in the Concentrate Here area (II) were related to economic feasibility such as reasonable price, appropriate price of set menu, telecommunication company affiliated service and coupon usage and point accumulation. As for the Keep up the Good Work area (I), there were many variables regarding personnel service including taste of side menu, blending with coffee, clean packing, clean packaging, staff's side menu knowledge, staff's quick response, staff's politeness and staff's sincere response. As for the variables in the Low Priority area (III), health variables on health such as nutritional value, eco-friendly food materials and calories were observed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.1
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• pp.1-7
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• 2014

Aluminum nitride, which has outstanding properties such as high thermal conductivity and electrical resistivity, has been received a great attention as a substrate and packaging material of semiconductor devices. Since aluminum nitride has a high sintering temperature of 2173 K and its properties depends on the impurity level, it is necessary to synthesize high-purity and nano-sized aluminum nitride powders for the applications. In this research, we synthesized high purity aluminum nitride nanopowders from aluminum using RF induction thermal plasma system. Sheath gas (NH3) flow was controlled to establish the synthesis condition of high purity aluminum nitride nanopowders. The obtained aluminum nitride nanopowders were evaluated by XRD, SEM, TEM, BET, FTIR and N-O analysis.

• Food Science and Preservation
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• v.10 no.4
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• pp.447-453
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• 2003

Causal factors related to the skin disorder such as black stains during cold storage of 'Niitaka' pear fruit are of great importance to solve the postharvest disorder problems. The morphological and biochemical changes observe of pear skin affected by different harvest times and storage environments. Occurrence rate of black stain in 'Niitaka' pear fruit was the highest in newspaper bagging with 75% among various bagging materials at harvest time because of the high relative humidity within the double layer paper bags. During cold storage, the rate was 54～100% in 30 $\mu\textrm{m}$ polyethylene (PE) film packaging. As the harvest time was postponed, the rate increasedduring cold stoinge. The into was 1.5 to 2.4 times higher in pears harvested in late September than in those harvested in early and mid October. There was no significant difference in occurrence of black stain fruit between the 30 and 50 $\mu\textrm{m}$ PE film bags. The causal fungus of the black stain pear was assumed as Gloeodes pomigena (Schweintz, 1920). The treatment of 0.1～0.5 ppm ozone gas prevented the occurrence of the pear fruit black stain until 180 days after cold storage. The ozone treatment on the affected fruit was also effective in preventing the progress of the black stain.

• Korean Journal of Food Science and Technology
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• v.13 no.4
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• pp.289-298
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• 1981

The texture characteristics, crispness and brittleness, of the barley flake developed by FRI in 1980 were measured with both sensory and instrumental methods. Bend and penetration test were done to determine those characteristics instrumentally, and compared each other and with sensory evaluation. And the changes in those characteristics with various water activity were studied, and the textural critical water activity was acquired. The shelf-life was also estimated with various packaging materials. It was found that crispness could be represented as the reciprocal of deformation and brittleness as that of fracture force in the barley flake. Both crispness and brittleness decreased as water activity increased. And the results from the penetration test correlated better with those from the sensory evaluation than the bend test's. The average shelf-life of the barley flake was 43 days in PE film and 9400 days in laminated Al foil on the basis of only textural characteristics.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.711-715
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• 2012

A laminate-composite film was developed using industry co-products of defatted mustard meal (DMM) and whey protein isolate (WPI). An individually prepared DMM-based film (DMM film) and a WPI-based film (WPI film) were thermally laminated at $130^{\circ}C$ at a rate of 30 cm/min. Microscopic images exhibited that the DMM film and the WPI film were continuously attached in the laminate without void spaces. The tensile strength, elongation at break, and water vapor permeability for the laminate were 0.7MPa, 4.0%, and $6.9g{\cdot}mm/kPa/h/m^2$, respectively. Stretchability and heat seal strength of the laminate were higher than those of the un-laminated DMM film. The film layers of the laminate were physically overlapped, not forming new biopolymer units induced by molecular interactions. The opportunity for DMM films to be used as food packaging materials for wrapping and sealing could be increased by thermal lamination with WPI films, which improves the stretchability and heat sealability of DMM films.

• Restorative Dentistry and Endodontics
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• v.42 no.2
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• pp.87-94
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• 2017

Objectives: Chitosan has been widely investigated and used. However, the literature does not refer to the shelf life of this solution. This study evaluated, through the colorimetric titration technique and an analysis of dentin micro-hardness, the shelf life of 0.2% chitosan solution. Materials and Methods: Thirty human canines were sectioned, and specimens were obtained from the second and third slices, from cemento-enamel junction to the apex. A 0.2% chitosan solution was prepared and distributed in 3 identical glass bottles (v1, v2, and v3) and 3 plastic bottles (p1, p2, and p3). At 0, 7, 15, 30, 45, 60, 90, 120, 150, and 180 days, the specimens were immersed in each solution for 5 minutes (n = 3 each). The chelating effect of the solution was assessed by micro-hardness and colorimetric analysis of the dentin specimens. 17% EDTA and distilled water were used as controls. Data were analyzed statistically by two-way and Tukey-Kramer multiple comparison (${\alpha}=0.05$). Results: There was no statistically significant difference among the solutions with respect to the study time (p = 0.113) and micro-hardness/time interaction (p = 0.329). Chitosan solutions and EDTA reduced the micro-hardness in a similar manner and differed significantly from the control group (p < 0.001). Chitosan solutions chelated calcium ions throughout the entire experiment. Conclusions: Regardless of the storage form, chitosan demonstrates a chelating property for a minimum period of 6 months.