• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.362-366
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• 2016

In this study, humidity control ceramics with good adsorption/desorption capabilities and high strength were fabricated from drinking-water treatment sludge (DWTS) and Onggi soil. The DWTS powder heat-treated at $800^{\circ}C$ and Onggi soil were mixed at weight ratios of 40:60, 50:50, 60:40, and 70:30 and fired at $800-1000^{\circ}C$. With increasing DWTS content, density and flexural strength increased. For the sample with a DWTS:Onggi soil weight ratio of 70:30, porosity and specific surface area decreased with increasing firing temperature, attributed to densification and grain growth at high firing temperatures. From the results obtained, a firing temperature of $800^{\circ}C$ is the optimum condition for fabricating humidity control ceramics with good adsorption/desorption capabilities and strength. The maximum adsorbed amount for the sample fired at $800^{\circ}C$ was $439g/m^2$.

• Journal of the Korean Ceramic Society
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• v.54 no.2
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• pp.114-120
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• 2017

In underdeveloped countries, many people suffer from water shortage due to the absence of water supply service. Although water purifiers have provided support in such situations, it is not easy to maintain water filters without a continuous supply of consumable filters. To obtain a sustainable drinking water source, appropriate technology of water treatment is necessary. Herein, a low cost water purification system was developed using natural raw materials. A non-electric water treatment system was developed using filtration through an Onggi filter, which is a type of Korean traditional earthenware with a microporous surface. The porosity and flux of the prepared Onggi filter were 29.06% and 31.63 LMH, respectively. After purification of water with total dissolved solids of 10.4 mg/L and turbidity of 100 NTU, the total dissolved solids and turbidity of the water treated using the Onggi filter decreased by 12% and 99.8%, respectively.

• Food Science and Biotechnology
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• v.14 no.1
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• pp.82-88
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• 2005

Ethnic Korean onggi earthenwares were fabricated using different clay formulations and glazing treatments. Their permeability properties against oxygen, carbon dioxide, and moisture were measured at $20^{\circ}C$ and examined from the aspect of food preservation. Onggi walls consisted of micropores that offered higher gas and moisture permeation rates when compared with other food packaging materials. Earthenware walls were unique in having $CO_2/O_2$ permeability ratios of 0.60-1.00. Gas and moisture permeabilities were lower, with wall structure having lower porosity and surface glazing. Results revealed onggi jar packages of grape fruits could attain wide range of $O_2$ and $CO_2$ concentrations. Onggi containers present good opportunity to obtain optimum packaging conditions for respiring or ripening products, depending on commodity type.

• Animal Bioscience
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• v.36 no.5
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• pp.797-809
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• 2023

Objective: Many scientists have investigated solutions to reduce microbiological risks in dry-aged meat after the dry-aging technology was revived for high quality and value-added premium meat product in the market. This study aimed to investigate the effect of scoria powder in onggi (Korean earthenware) on the meat quality of pork loins during 21 days of dry aging and to elucidate its mechanism of action. Methods: The pork loins were randomly divided into three groups: aged in vacuum-packaging, onggi containing red clay only (OR), and onggi containing 30% red clay and 70% scoria powder (OS). Microbial analyses (total plate count and Lactobacillus spp.) and physicochemical analyses (pH, shear force, volatile basic nitrogen [VBN], water activity, 2-thiobarbituric acid reactive substances, water content, water holding capacity, cooking loss, and color analysis) of aged meat were conducted. Far-infrared ray emission, quantification of immobilized L. sakei and microstructure of onggi were investigated to understand the mechanism. Results: On day 21, the meat aged in OS exhibited lower pH, shear force, VBN, and water activity than those aged in OR, along with an increase in the number of Lactobacillus spp. OS had a smaller pore diameter than OR, implying lower gas permeability, which could promote the growth of L. sakei. Conclusion: OS improved the microbiological safety and storage stability of pork loin during dry aging by increasing number of Lactobacillus spp. possibly due to low permeability of OS.

• Journal of agriculture & life science
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• v.45 no.1
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• pp.59-66
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• 2011

This study was conducted to investigate the effect of vase material and floral preservative treatment over time on flower color, leaf color and flower size of cut flowers Rosa hybrida 'Aqua' and 'Corvernet', and Gerbera jamesonii 'Honeymoon' and 'Golden Time' stuck in a glass, porcelain, or onggi (pottery with a dark bronze glaze) vase containing either tap water or a floral preservative solution. The ${\Delta}E$ values in flower color of 'Aqua' rose at 8 days after treatment with a floral preservative in onggi and porcelain vases were low. The ${\Delta}E$ value of 'Covernet' rose treated with floral preservative in an onggi vase was the lowest and L value was the closest to that of petals of cut flowers at just before treatment (control). The ${\Delta}E$ value of 'Honeymoon' gerbera treated with a floral preservative in an onggi vase was the lowest and a value of 58.81 and b value of 34.29 were the closest to that of the control group as color of cut flowers in an onggi vase was similar to the color at the beginning of treatment. The ${\Delta}E$ value of 'Golden Time' gerbera treated in an onggi vase was significantly lower than that in a porcelain or glass vase and a value of -7.81 treated with a floral preservative solution in an onggi vase was the closest to the control and b value was high in an onggi vase as well. The L, a, and b values in leaf color of roses were similar to each value of the control and ${\Delta}E$ value of 3.25 measured in an onggi vase was lower than that in a porcelain or glass vase. Flower diameter of 'Covernet' and 'Golden Time' roses treated with a floral preservative in an onggi vase was greater than that in other treatments. From these results, the floral preservative applied to a holding solution is assumed to improve the quality and freshness of cut roses and gerberas by inhibiting microbes propagation and by promoting uptake of water and nutrients. The onggi vase with fine pores will promote the expression and maintenance of flower and leaf colors and may increase flower diameter by high air permeability.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.13 no.2
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• pp.51-58
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• 2007

This research investigated the effect of different onggi containers (Korean earthenware) on the ripening of kochujang (Korean hot pepper paste). The physical characteristics of 'onggi', were evaluated as function of manufacturing variables such as raw material soils (onggi-specific soil, red brown soil, and fine powdered soil) and galzing treatments. The physical properties were then related to the compositional quality changes of the kochujang fermented at $30^{\circ}C$ for 4 months. The porosity of the onggi containers seems to be increased by the content of finer raw soil rather than the chemical component of soil (amount of CaO, MgO, $K_2O$ and $Na_2O$, acting as melting aid in the firing). Natural glaze was measured to contain higher contents of CaO, MgO, $K_2O$ and $Na_2O$ than the other soils, which is desirable property for the fired onggi. The glazed surface showed higher far-infrared radiation emissivity than the non-glazed part. The kochujang fermented in P0-BG (the glazed onggi from 100 % onggi soil) attained higher concentration of reducing sugar, amino nitrogen and nucleotides compared to those in the other onggis. All of these changes of kochujang in P0-BG resulted in significantly better sensory quality than the other treatments.

• Food Science and Preservation
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• v.11 no.2
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• pp.233-239
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• 2004

Anchovy soy sauce containing anchovy sauce was ripened in different vessels at 30$^{\circ}C$ for 4 months and measured in physical, chemical, microbiolgical and sensory quality attributes. The used vessels include glass, polypropylene (PP), polyethylene terephthalate (PET), stainless, and onggi (Korean earthenware) with 628 mL. Compared to the other vessels, onggi gave the highest moisture loss, maintained consistently higher microbial counts in total aerobic bacteria, lactic acid bacteria and yeasts, and attained high protease activity in the soy sauce product. Even with high moisture loss the onggi vessel did not produce the higher product salt content than the other vessels because there was salt diffusion outward through the container wall. All of these changes of the product in onggi resulted in lower pH, higher acidity and higher amounts of free amino acids and nucleotides after 4 month period, which was desirable for sensory quality.

• Journal of the Korean Ceramic Society
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• v.55 no.2
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• pp.153-159
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• 2018

Porous ceramic plates were prepared from Onggi clay and bamboo charcoal powder at 1100 and $1200^{\circ}C$ and their porous properties and water absorption, and the cooling effect of porous plates, were investigated to produce eco-friendly porous ceramics for a self-cooling system that relies on the evaporation of absorbed water. Porous properties were dependent on the particle size of charcoal powder pore forming additive and the firing temperature; properties were also found to be dependent on the total pore volume, average pore size and porosity, which had values of $0.103-0.243cm^3/g$, 0.81 - 2.56 mm and 20.9 - 38.2%, respectively, at $1100^{\circ}C$ and $0.04-0.18cm^3/g$, 0.33 - 2.03 mm and 10.8 - 30.9%, respectively, at $1200^{\circ}C$. Cooling temperature difference of flowing air parallel to surface of porous ceramic plates fired with two kinds of charcoal powder at $1100^{\circ}C$ was $3.5-3.6^{\circ}C$ at $26^{\circ}C$ and 60% of relative humidity in a closed box. Cooling temperature difference was dependent on the number of porous plates and the distance between porous plates. A simple and eco-friendly cooling system using porous ceramic plates fired from Onggi clay and charcoal powder was proposed.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.12 no.2
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• pp.87-90
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• 2006

Thermal and gas adsorption properties were measured for Korean earthenware (onggi) as a step to elucidate its role as food preserving container. Thermal conductivity and diffusivity decreased with increase in porosity while heat capacity depended on the raw soil component rather than porosity. Thermal barrier of the earthenware was generally similar to that of glass. The onggi material could sorb or adsorb a limited amount of water vapor, $CO_2$ and ethylene gases (0.0005 g/g, $17{\mu}g/g$, $2.6{\mu}g/g$, respectively). Thermal and gas adsorption properties of onggi seem to provide unique application area for use as food container and packaging.

• Journal of the Korean Society of Clothing and Textiles
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• v.42 no.4
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• pp.689-707
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• 2018

This study reviewed the differences among Onggis made in Jeju and other areas, developed creative textile designs and cultural products, and conducted the consumer evaluation of developed products. First, the 1,063 photos of Onggis made before the first part of the 20th century were collected and the unique differences of Jeju Onggis were confirmed through the observation of collected photos. Second, based on the uniqueness of Jeju Onggis, the eight pieces of Jeju Onggis were selected from the photos and used as pattern design motifs. Nine basic patterns were drawn and ten textile designs were created using the basic patterns. Third, the 16 pieces of textile products were made with cotton fabrics on which the textile designs were printed. Four mugs and four tumblers with printed patterns were also made. Finally, 64 students evaluated the developed products using a 7-point scale. As a result, folksy atmosphere, uniqueness, usage as a Jeju souvenir and at local restaurants, and the role of fostering concern for Jeju Onggi were highly evaluated but aesthetics was rated relatively low. Most of the developed products were highly preferred and recommended as Jeju souvenirs or for local restaurants.