• Food Engineering Progress
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• v.23 no.1
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• pp.55-61
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• 2019

For the vessel export of strawberries, modified atmosphere package (MAP) using polyamide (PA) film and linear low density polyethylene (LLDPE) film was investigated to extend the shelf life of strawberries. Because the temperature and relative humidity changes of the MAP were lower than the changes of the control, the weight loss of the MAP were lower than that of the control. The low oxygen level and high carbon dioxide level were effective to decrease the fungal decay rate and to increase the hardness of strawberries. The Hunter's color differences before and after storage showed no distinct difference between the MAP and the control. The lightness had a tendency to decrease while the redness increased. There were no significant changes of the soluble solids during the storage. The shelf life of strawberries could be extended to 16 days using the MAP considering the weight loss and the fungal decay rate. Thus, this MAP method using PA film and LLDPE film was effective to extend the shelf life of strawberries.

• Journal of Powder Materials
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• v.8 no.2
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• pp.131-135
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• 2001

The ferroelectric properties of barium titanate strongly depend on its microstructure, in particular, grain size and distribution. During sintering, $BaTiO_3$ usually exhibits abnormal grain growth, which deteriorates considerably the ferroelectric properties. A typical technique to suppress the abnormal grain growth is the addition of dopants. Dopant addition, however, affects the ferroelectric properties and thus limits the application of $BaTiO_3$. Here, we report a simple but novel technique to prevent the abnormal grain growth of $BaTiO_3$ and to overcome the limitation of dopant use. The technique consists of stepwise sintering in a reducing atmosphere and in an oxidizing atmosphere. The materials prepared by the present technique exhibit uniform grain size and high dielectric properties. The technique should provide opportunities of having $BaTiO_3$-based materials with superior ferroelectric properties.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.129-132
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• 2007

In this study, for the establishment of the performance evaluation methods of repair material and method for reinforced concrete structure and the quality control standards of durability recovery method, the quantitative exposure data by exposure experiment under the coastal and normal atmosphere environment is accumulated and analyzed. Investigating and evaluating the result of exposure experiment during 54 months of exposure age under the coastal and normal atmosphere environment, Micro crack, swelling and spatting of surface coating material, crack of repair boundary parts and the great potential difference between repair part and non-repair part were somewhat generated. And the result shown that exposure specimen of coastal environment had lower electrode potential than exposure specimen of normal atmosphere environment.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.4
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• pp.191-196
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• 2003

For improvement of the wear performance of Ti alloy, vacuum-carburizing technique was tried for the first time using propane atmosphere. During the low pressure carburizing carbide was formed at the surface and carbon transfer was occurred from the carbide to the matrix. It was found that: (i) surface hardness increased with the reduction of operating pressure and time; (ii) optimum hardness distribution could be obtained with the proper choice of temperature and carbon flux control; and, (iii) case depth was largely influenced not by time but by temperature. The two steps process was recommended for obtaining thick case depth and high surface hardness of Ti alloy. For the low oxygen partial pressure, it was necessary to introduce additional CO gas to the atmosphere.Grain boundary oxidation and non-uniformity could be prevented.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.4
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• pp.418-421
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• 2023

Multilayer Ceramic Capacitors (MLCCs) are essential passive components in the electronics industry, known for their high capacitance due to the multilayer structure comprising inner electrodes and dielectric layers. Nickel electrodes are commonly used in MLCCs as the inner electrodes, and to prevent oxidation during the co-firing of the dielectric layers with nickel electrodes, reducing atmosphere is required. However, reducing atmosphere sintering can also induce a reduction of the dielectric, necessitating precise control of oxygen partial pressure. To explore the possibility of using oxide electrodes that do not require reducing atmosphere sintering, we analyze the electrical properties of nickel oxide (NiO) as a potential candidate. As a preliminary study on its use as an alternative inner electrode, the correlation between microstructure and electrical properties of bulk NiO under different sintering conditions was investigated to gain insights into the conduction mechanisms of the material.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.811-821
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• 2018

This study focused on the improvement of blueberry delivery service using pre-cooled ice and $SO_2$ pads to prevent an increase in the fruit temperature as well as decay. To maintain the fruit quality during low temperature storage, the effect of a $SO_2$ pad and modified atmosphere packaging was also examined. Harvested blueberries were precooled at $15^{\circ}C$, sorted, and packaged. And the fruits were placed in a similar environment as that for the parcel service. Part of the fruits were stored at $0^{\circ}C$ for long term storage. The air temperature in the delivery box increased along with an increase in the simulated delivery time regardless of the treatment. However, the rate of temperature increase was lower in the ice pad treatment. No significant difference was not found after 48 h. The oxygen concentration in the box ranged between 10.5 - 14.5% in the ice pad treatment, which was higher than that of the untreated control (7.5 - 11.9%) whereas the $CO_2$ concentration was lower in the ice pad treatment. No differences were found in the occurrence of off-flavor, decay, and sensory quality loss during the 48 hours of the parcel service simulation. The combined treatment of the $SO_2$ pad and modified atmosphere packaging (MAP) using a perforated film increased the shelf-life of the blueberry fruits, the overall quality such as firmness, and the soluble solid content was not different between the treatments except for the decay incidence. No decayed fruit was found in the combined treatment. However, the percentage of decayed fruit in the control was 25% on day 15 of storage and 75% on day 33 of storage, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.1047-1052
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• 1989

A novel multi-purpose monitoring platform-LTA vehicle is presented with much improved kinetic performances together with its structural analysis and its scale model test data. This provides a useful mean of monitoring, exploring and remote sensing platform that flies over the wide range of atmosphere and can be used as a safe economic device.

• Food Science of Animal Resources
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• v.38 no.3
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• pp.593-605
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• 2018

The present study was undertaken to assess the efficacy of sapota powder (SP) as natural preservatives and its better utilization in food processing with the incorporation of various levels of SP (2, 4, and 6%) by replacing lean meat. Based on the sensory attributes, pork patties with 4% incorporation of SP was found optimum and selected for further storage studies with control under aerobic and modified atmosphere packaging at refrigeration temperature ($4{\pm}1^{\circ}C$) for 42 days for assessing its antioxidant and antimicrobial efficiency. During entire storage period, indicators of lipid oxidative parameters such as thiobarbituric acid reactive substances (TBARS), free fatty acids (FFA) and peroxide value (PV) followed an increasing trend for control as well as treated products; however, treated product showed a significantly (p<0.05) lower value than control. A significantly lower (p<0.05) microbial count in treated patties than control was noted during entire storage. The sensory attributes are better retained in treated product as compared to control and even on $42^{nd}$ day, overall acceptability of treated patties was found to fall in moderately acceptable category (5.95 in aerobic packets and 5.91 in modified atmosphere packets). Therefore SP has potential to enhance antioxidant and antimicrobial properties of pork patties during storage.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1018-1021
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• 2006

Powdered metal parts and components may be carburized successfully in a vacuum furnace by combining carburizing technology $VacCarb^{TM}$ with a hi-tech control system. This approach is different from traditional carburizing methods, because vacuum carburizing is a non-equilibrium process. It is not possible to set the carbon potential as in a traditional carburizing atmosphere and control its composition in order to obtain a desired carburized case. This paper presents test results that demonstrate that vacuum carburizing system $VacCarb^{TM}$ carburized P.M. materials faster than traditional steel with acceptable results. In the experiments conducted, PM samples with the lowest density and open porosity showed a dramatic increase in the surface carbon content up to 2.5%C and a 3 times deeper case. Currently the boost-diffusion technique is applied to control the surface carbon content and distribution in the case. In the first boost step, the flow of the carburizing gas has to be sufficient to saturate the austenite, while avoiding soot deposition and formation of massive carbides. To accomplish this goal, the proper gas flow rate has to be calculated. In the case of P.M. parts, more carbon can be absorbed by the part's surface because of the additional internal surface area created by pores present in the carburized case. This amount will depend on the density of the part, the densification grade of the surface layer and the stage of the surface. "as machined" or "as sintered". It is believed that enhanced gas diffusion after initial evacuation of the P.M. parts leads to faster carburization from within the pores, especially when pores are open . surface "as sintered" and interconnected . low density. A serious problem with vacuum carburizing is delivery of the carbon in a uniform manner to the work pieces. This led to the development of the different methods of carburizing gas circulation such as the pulse/pump method or the pulse/pause technique applied in SECO/WARWICK's $VacCarb^{TM}$ Technology. In both cases, each pressure change may deliver fresh carburizing atmosphere into the pores and leads to faster carburization from within the pores. Since today's control of vacuum carburizing is based largely on empirical results, presented experiments may lead to better understanding and improved control of the process.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.1053-1057
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• 2007

One of the important roles of glass is safety guarantee in CRTs. It is working under high vacuum and has to be maintained continuously for the atmosphere pressure, humidity, and excitation etc,. This paper propose to CRTs glass design method via the stress positioning control for slim CRTs using FEM to ensure the national safety standard and newly demanded safety standard by CRTs set makers.