• Korean Journal of Heritage: History & Science
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• v.36
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• pp.267-297
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• 2003

The plain coarse pottery from the Unjeonri Bronze Age relic sites in the Cheonan, Korea were studied on the basis of clay mineralogy, geochemistry and archaegeological interpretations. For the research, the potteries are utilized at the analysis for 6 pieces of plain coarse potteries. Color of the these potteries are mainly light brown, partly shows the yellowish brown to reddish brown. The interior, surface and inside of the pottery appear as different colors in any cases. Original source materials making the Unjeonri potteries are used of mainly sandy clay soil with extreme coarse grained irregularly quartz and feldspar. The magnetic susceptibility of the Unjeonri pottery range from 0.20 to 1.20. And the Unjeonri soil's magnetic susceptibility agree almost with 0.20 to 1.30. In the same magnetization of soil and pottery, the results revealed that the Unjeonri soil and low material of pottery are same produced by identical source materials. The Unjeonri potteries and soil are very similar patterns with all characteristics of soil mineralogy, geochemical evolution trend. The result seems to be same relationships between the behavior and enrichment patterns on the basis of a compatible and a incompatible elements. Consequently, the Unjeonri potteries suggest that made the soil to be distributed in the circumstance of the relic sites as the raw material are high in a greater part. In the Unjeonri soil, the kaolinite is common occurred minerals. However, in the Unjeonri pottery, the kaolinite was not detected in all broken pieces. The kaolinite was presumed to destroy crystal structure during the firing processes of over $550^{\circ}C$. The quartz is phase transition from ${\alpha}$-quartz to ${\beta}$-quartz at $573^{\circ}C$, but the Unjeonri pottery did not investigated any phase transition evidences of quartz. The chorite was detected within the mostly potteries and soils. As the results, the Unjeonri potteries can be interpreted by not experiencing a firing temperature over $800^{\circ}C$. The colloidal and cementing materials between the quartz and low materials during the heating did not exist in the internal part of the potteries. An any secondary compounds by heating does not appear within the crack to happen during the dry of the pottery. The hyphae group are kept as it is with the root tissue of an organic matters to live in the swampy land. In the syntheses of all results, the general firing condition to bake and make the Unjeonri pottery is presumed from $550^{\circ}C$ to $800^{\circ}C$. However, the firing condition making the Unjeonri pottery can be different firing temperature partially in one pottery. Even, the some part of the pottery does not take a direct influence on the fire.

• ALGAE
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• v.34 no.1
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• pp.7-21
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• 2019

The genus Heterocapsa is one of the major dinoflagellate groups, with some of its species having worldwide distributions. However, prior to the present study, the phototrophic species Heterocapsa minima has been reported only from the northeast Atlantic Ocean. Recently, H. minima was found in the Korean waters, and a clonal culture was established. This culture was used to examine the morphology of the Korean strain H. minima HMMJ1604 through light and scanning electron microscopy, as well as for its genetic characterization. Furthermore, to determine the nationwide distribution of H. minima in Korea, its abundance was quantified in the waters of 28 stations in all four seasons in 2016-2018 using the quantitative real-time polymerase chain reaction method. The overall morphology of H. minima HMMJ1604 was very similar to that of the Irish strain H. minima JK2. However, the Korean strain had five pores around the pore plate, whereas the Irish strain had six pores. When properly aligned, the sequences of the large subunit and internal transcribed spacer regions of the ribosomal DNA of the Korean strain were identical to those of the Irish strain. This species was detected in the waters of 26 out of 28 stations, but its abundance was greater than $1.0cells\;mL^{-1}$ at 8 stations. The highest abundance of H. minima was $44.4cells\;mL^{-1}$. Although this species was found in all seasons, its abundance was greater than $1.0cells\;mL^{-1}$ when the water temperature and salinity were $10.9-25.0^{\circ}C$ and 17.5-34.1, respectively. To the best knowledge, the present study reported for the first time that H. minima lives in the Pacific Ocean and is widely distributed in the Korean waters.

• Korean Journal of Food Science and Technology
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• v.52 no.6
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• pp.661-669
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• 2020

Samgak-Kimbap is a popular ready-to-eat (RTE) food at convenience stores, in Korea. Although Samgak-Kimbap is distributed through the cold chain supply system, inappropriate temperature storage conditions prior to consumption are a cause of concern. The objective of this study was to evaluate the risk of Staphylococcus aureus growth in Samgak-Kimbap in the retail market. The prevalence and contamination levels of S. aureus in Samgak-Kimbap (n=170) were monitored, and the predictive growth model of a five-strain cocktail of enterotoxin-producing S. aureus (SEA, SEB, SEC, SED, and SEE) was developed in Samgak-Kimbap as a function of temperature (4, 10, 11, 20, 25, and 37℃). We could not observe the growth of S. aureus and enterotoxin-producing S. aureus in Samgak-Kimbap at temperatures below 10℃. The probability of illness with S. aureus per serving of Samgak-Kimbap was 1.44×10-10 per day. The most influential factor in increasing the risk of foodborne illnesses was the contamination level of S. aureus in Samgak-Kimbap.

• Journal of Conservation Science
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• v.37 no.2
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• pp.77-89
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• 2021

In this study, materials and color formation techniques were assessed for black potteries excavated from the Janghyeon-dong, Jungsan-dong and Gyodong-ri sites during the Proto-Three Kingdoms period in Ulsan, Korea. Although the black potteries were black superficially, the inner cores were either black or reddish yellow. Microscopy analysis identified that body clay was used for reddish iron oxide rich soils with quartz, alkali feldspar and mica, along with grains of myrmechite texture. Additionally, as marginal differences exist in the contents of SiO₂, Fe₂O₃ and CaO, the composition of the host rock and clay distributed around the sites was affected. Thus, we can deduce that pottery was made by soiling at a short distance. Raman spectroscopy results revealed that the black layer of the black pottery was used as amorphous combustion carbon. In addition, as a transparent layer of brown lacquer was observed on the substrate that was in contact with the surface layer, the black layer of the pottery induced black color development by a combination of combustion carbon and lacquer. Based on the mineral composition and microtexture of the body clay, the firing temperature of the potteries seemed to range from 750 to 850℃, whereas the lacquer layer was pyrolyzed at 468℃ by thermal analysis. Therefore, a combined layer of combustion carbon and lacquer, which formed the black color, was painted after the body clay was fired.

• Journal of Food Hygiene and Safety
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• v.38 no.4
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• pp.236-245
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• 2023

In this study, the quality safety limit period of seven types of bakery bread was analyzed, and their use-by date was calculated. For evaluating product quality, storage conditions were set as 5, 15, 25, and 35℃ for 50 days, and moisture, microorganisms, sensory characteristics, and dominant bacteria were examined. The quality and safety standards followed the Korea Food Code and Korean industrial standards (KS). The results showed that all products stored at 5℃ satisfied the standard for bacterial count for day 50, but the sensory quality was below the standard level. Samples stored at 15℃ showed high variability from 3-39 days. At 25℃, a quality safety limit period of 2-20 days was set, and one sample was found to have the same shelf life. Bread stored at 35 ℃ had the shortest quality safety limit period. Considering a safety factor of 0.87, a use-by date period of 1.7-13.1 days was calculated. Therefore, setting the use-by date according to the product type is necessary, even for the same product category. Among the bread products sold in bakeries, those managed as room temperature products (1-35℃) can be distributed and stored in a temperature range of up to 35℃. Overall, this study demonstrates the importance of setting a quality retention period based on the product characteristics and carefully considering the safety factor.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.571-582
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• 2022

In this study, the raw material and tempers of bricks used in three brick tombs built in Gongju, during the Ungjin period of Baekje were investigated. The royal tomb of King Muryeong, the 6th tomb in the royal tombs, and Kyochonri brick tomb remained in Gongju and the bricks of each site had different shape and physical properties despite their similarity in raw materials. As the results of the mineralogical and microstructural analysis, the bricks of the royal tombs were made of refined raw materials, and were infrequently added crushed bricks(grogs) as a tempering material. On the other hand, thick and elongated pores of bricks from the Kyochonri brick tomb were frequently found, and the remains of plant carbonization are observed in their microstructures. Since the pores are mainly distributed in a thickness of 0.3 to 1 mm, it is estimated that bricks were produced by adding a certain size of the plant to refined soil, and grogs also were added as a tempering material. In particular, it was found that adding plants and grogs in raw materials of bricks caused thick pores or cracks in the internal structure. Since the bricks of the Kyochonri brick tomb have internal cracks and low firing temperature, the ultrasonic velocity of the bricks was lower than that of the royal tomb bricks. It means that the mechanical strength of these bricks were relatively low. Accordingly, it is estimated that the tempering materials, firing temperature, and internal structures of bricks can affect durability of the brick, and it can be thought as a difference in the manufacturing technology of brick making.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.93-102
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• 2023

Objectives: With the evolution of direct reading sensors, it is possible to monitor several substances through telecommunication. However, there are some limitations on the use of direct reading technologies in the Occupational Safety and Health Act in South Korea, which only applies to detector tubes, noise, heat, and carbon monoxides. The number of chemicals and their amount of use have been continuously increasing in South Korea. The Ministry of Employment and Labor (MoEL) has concerns about worker's health because exposure is only covered for about 1.2% of all distributed chemicals. Using a direct reading monitor with photoionization detectors (PID-DRMs), gases and vapors chemicals can be measured. Based on the data, business owners are able to create corrective strategies, provide better working routines, and select correct respiratory equipment. PID-DRMs are less expensive and easier to handle for an owner voluntarily controlling chemicals emitted in the workplace. However, there are several limitations on using these PID-DRMs to the degree that the MoEL has not been able to select a legal monitor. The aim of this study was to review previous studies related to PID-DRMs and identify the characterization and limitation on PID-DRMs. Methods: To search for related studies on PID-DRMs, key words were used including direct reading monitors/instruments and/or photoionization detectors. Through that, four domestic and 15 international studies were reviewed. Results: Studies on PID-DRMs were conducted by chamber (enclosed, dynamic, walk-in) and in the field (experimental environment, actual environment). The concentration of PID-DRMs and charcoal tubes were compared for a single substance or mixture, or within the PID-DRMs. There was a high correlation between the two concentrations, but it did not meet the accuracy criteria (95% confidence interval, within 25%) of the NIOSH technical report (2012). In addition, differences in measured values occurred according to environmental factors (temperature, humidity) and high concentration, and concentration values tended to be underestimated due to contamination of the sensor. As a way to improve the accuracy of PID concentration, it was proposed to use correction factors, charcoal tube-based correction factors, or to calibrate the PID-DRMs in the same environment as the workplace. Conclusions: PID-DRMs can likely be used by business owners for the purpose of voluntarily managing the workplace environment, and it is expected that it will be possible to use them as legal equipment if a PID sensor can be upgraded and the limitations of the sensor (temperature, humidity, high concentration evaluation, sensor pollution) can be overcome in the near future.

• Journal of the Korean Society of Food Culture
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• v.25 no.5
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• pp.615-624
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• 2010

This study was conducted to investigate the use of sugar alcohols as alternative sweeteners for replacing sucrose in sponge cake. The sponge cakes were prepared with only sucrose or a 50% replacement of sucrose with various sugar alcohols (erythritol, sorbitol, and xylitol). The specific gravity of cake batter containing only sucrose was significantly higher and the viscosity was significantly lower than those containing sugar alcohol (p<0.001). Among sugar alcohols, xylitol was the most similar to sucrose. The thermal characteristics, as assessed by differential scanning calorimetry, showed that sucrose delayed gelatinization of cake batter more than sugar alcohol, as the onset temperature and the peak temperature of cake batter containing only sucrose were higher than those containing sugar alcohol. The moisture content of cake containing sorbitol was the highest and that containing only sucrose was the lowest among cakes. The specific volume of cakes containing only sucrose and xylitol were higher and the baking loss rate of those were lower than other sugar alcohols. The volume and symmetry index of cake containing only sucrose were the highest among cakes (p<0.001), and xylitol was similar to sucrose for the above indices. The redness (a) and yellowness (b) values of crust containing only sucrose were significantly higher than those containing sugar alcohols (p<0.001). The a and b values of crumb containing erythritol were the lowest among cakes, showing a pale yellowish color. The microstructure, as assessed by scanning electron microscopy, showed that the cake containing only sucrose had more uniformly and finely distributed pores and a smoother cross section than that containing sugar alcohols. Cake containing xylitol was similar to cake containing only sucrose. Hardness, chewiness, and gumminess of cake containing only sucrose were higher than those containing sugar alcohols, whereas the adhesiveness of cakes containing sugar alcohols were higher than those containing only sucrose (p<0.01). Among sugar alcohols, xylitol was the most similar to sucrose in textural properties. In a sensory quality test, the tenderness and moistness of cakes containing sorbitol and erythritol were higher than those containing only sucrose and xylitol. The overall acceptance of cakes containing xylitol and only sucrose were higher than those containing sorbitol and erythritol (p<0.001). Thus, xylitol is more appropriate as a 50% replacement for sucrose than erythritol and sorbitol when preparing sponge cake.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.439-446
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• 2023

Mangroves are distributed in intertidal zones of coastal environments or estuarine margins, playing a critical role in the global carbon cycle. However, understanding of the carbon cycle role of mangrove associates in the Republic of Korea is still limited. This research measured soil respiration and leaf gas exchange in three habitats of Hibiscus hamabo(Gimnyeong, Seongsan, and Wimi) and analyzed the impacts on sites and months. Soil respiration was measured once a month from June to October 2022 and leaf gas exchange was measured monthly from June to September 2022. Soil respiration in August(5.7±0.8 μmol CO₂ m^-2 s^-1) was significantly higher than that in other months (p<0.001) and soil respiration increased as air temperature increased (p<0.001). In Seongsan, net photosynthesis in July(9.0±0.9μmol m^-2 s^-1) was significantly higher than that in other months (p<0.001). Net photosynthesis increased as stomatal conductance and transpiration rate increased during the entire period(p<0.001). Furthermore, a weak positive linear relationship was observed between soil respiration and net photosynthesis (r²=0.12; p<0.01). The results indicated that soil respiration was influenced not only by air temperature and season but also by net photosynthesis. This study is expected to provide basic information on the carbon dynamics of mangrove associates.

• Journal of Food Hygiene and Safety
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• v.31 no.6
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• pp.426-431
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• 2016

To compare the quality characteristics of commercial wasabi paste products, the physicochemical and microbial characteristics of 6 samples were analyzed. In addition, the contents of allyl isothiocyanate, which show unique flavor and antimicrobial activity in wasabi paste products, were compared. pH of commercial 6 wasabi products were ranged from $4.12{\pm}0.01$ to $4.90{\pm}0.01$, and titratable acidities of products distributed at cold temperature (CW) were higher $0.60{\pm}0.00{\sim}0.77{\pm}0.02%$ than those of products distributed at room temperature (RW). Salinities of RW were higher ($4.27{\pm}0.06{\sim}7.53{\pm}0.12%$) than those of CW ($2.20{\pm}0.00{\sim}3.60{\pm}0.10%$). Soluble solid and sorbitol contents of RW were higher ($33.00{\pm}1.00{\sim}44.67{\pm}2.08^{\circ}Brix$, $378.90{\pm}63.79{\sim}724.37{\pm}7.85mg%$) than those of CW ($22.00{\pm}1.73{\sim}27.00{\pm}1.00^{\circ}Brix$, $27.67{\pm}9.92{\sim}175.31{\pm}10.56mg%$), respectively. The viable cell counts of samples were $ND{\sim}3.65{\pm}0.23 log\;CFU/g$ without distribution method and packaging type, and yeasts and molds were not detected in 6 wasabi products. Allyl isothiocyanate contents of RW were higher ($53.35{\pm}0.08{\sim}159.76{\pm}0.81mg%$) than those of CW ($24.07{\pm}7.69{\sim}48.19{\pm}0.15mg%$).