• Journal of Microbiology and Biotechnology
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• v.33 no.2
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• pp.219-227
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• 2023

Lettuce is one of the most consumed vegetables worldwide. However, it has potential risks associated with pathogenic bacterial contamination because it is usually consumed raw. In this study, we investigated the changes in the bacterial community on lettuce (Lactuca sativa L.) in Chungcheong-do, South Korea, and the prevalence of foodborne pathogens on lettuce in different seasons using 16S rRNA gene-based sequencing. Our data revealed that the Shannon diversity index showed the same tendency in term of the number of OTUs, with the index being greatest for summer samples in comparison to other seasons. Moreover, the microbial communities were significantly different between the four seasons. The relative abundance of Actinobacteriota varied according to the season. Family Micrococcaceae was most dominant in all samples except summer, and Rhizobiaceae was predominant in the microbiome of the summer sample. At the genus level, the relative abundance of Bacillus was greatest in spring samples, whereas Pseudomonas was greatest in winter samples. Potential pathogens, such as Staphylococcus and Clostridium, were detected with low relative abundance in all lettuce samples. We also performed metagenome shotgun sequencing analysis on the selected summer and winter samples, which were expected to be contaminated with foodborne pathogens, to support 16S rRNA gene-based sequencing dataset. Moreover, we could detect seasonal biomarkers and microbial association networks of microbiota on lettuce samples. Our results suggest that seasonal characteristics of lettuce microbial communities, which include diverse potential pathogens, can be used as basic data for food safety management to predict and prevent future outbreaks.

• Korean Journal of Environmental Biology
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• v.42 no.2
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• pp.176-186
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• 2024

This study aimed to provide ecological information by identifying the stand characteristics of Larix kaempferi forest vegetation (deforestation, forest influence, patch, forest) for aggregated retention harvest in Mt. Nambyeongsan, Pyeongchang-Gun. Data were collected using the Braun-Blanquet vegetation survey method from July 2020, with 54 quadrats analyzed for importance value, species diversity, similarity index, and detrended correspondence analysis (DCA). The results showed that vine species had a higher importance value in the deforestation area and forest influence area. Forest regions had the highest species diversity (2.419), while the forest influence area had the lowest(2.171). The similarity index was highest between the forest region and patch area (0.723), and lowest between the patch area and forest influence area (0.658), which was consistent with the DCA results. In conclusion, although species diversity temporarily showed higher values in the initial stage after aggregated retention harvest, it was difficult to assign ecologically specific meanings to these values. Long-term monitoring is therefore necessary to accumulate ecological information on aggregated retention harvests.

• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.507-517
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• 2010

Long-term monitoring was conducted to identify the runoff characteristics of non-point source according to the three forest types (deciduous forest, coniferous forest and mixed forest) in this study. Rainfall events of each deciduous forest, coniferous forest, and mixed forest were 10, 8, 12, respectively. Average runoff depth and coefficients of each forest type were founded to be coniferous forest and were followed by others in turns : deciduous forest, and mixed forest because various conditions (i.e., rainfall property, Antecedent Precipitation Index (API), soil property, slope, and forest management) could change runoff characteristics. In the analysis of the first flush phenomenon, it showed that SS and T-P were sensitive for the first flush phenomenon. The first flush phenomenon of them were showed differently by rainfall intensity, rainfall duration, and amount of rainfall. The research results indicated that range of the Event Mean Concentration (EMC) values in deciduous forest were 0.8~2.4 mg/L for $BOD_5$, 2.0~13.4 mg/L for $COD_{Mn}$, 1.3~2.9 mg/L for DOC, 1.150~3.913 mg/L for T-N, 0.010~0.350 mg/L for T-P and 3.1~291.8 mg/L for SS and in coniferous forest were 0.8~2.2 mg/L for $BOD_5$, 1.9~3.6 mg/L for $COD_{Mn}$, 1.0~2.0 mg/L for DOC, 1.025~2.957 mg/L for T-N, 0.002~0.084 mg/L for T-P and 0.8~5.4 mg/L for SS. Also, range of the EMC values in mixed forest were 1.3~2.3 mg/L for $BOD_5$, 2.4~4.8 mg/L for $COD_{Mn}$, 1.1~2.1 mg/L for DOC, 0.385~2.703 mg/L for T-N, 0.016~0.080 mg/L for T-P and 2.3~30.0 mg/L for SS.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.2
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• pp.137-145
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• 1990

Six commercial rice varieties were cultivated at different locations in 1987 and 1988. Rice samples harvested from 8 to 20 locations for a variety each year were used to measure or observe grain appearance, amylose content and alkali digestibility, cooked rice texture using rheometer, gelatinization and viscosity of rice flour using amylograph, and eating Quality of cooked rice by sensory evaluation. Relationship between Quality characteristics showing large locational variation were analized to approach the long-term objective, rice grain Quality standardization. Percent white-center and white-belly grain of the same variety showed great variation between locations, but did not affect on 1000-grain weight, amylose content and alkali digestibility, amylogram and rheogram characteristics, and eating Quality of cooked rice. Positive correlationship were obtained between maximum viscosity and break down, and maximum viscosity and alkali digestibility. Set back was correlated negatively with maximum viscosity, break down and alkali digestibility. Rice samples having significantly lower values of maximum viscosity and break down and higher set back value at the same time showed higher ADV and lower texture palatability index (TPI) and viscousness/hardness ratio (Vi/H), and lower sensory evaluation score of cooked rice compared with those of rices having typically higher values of maximum viscosity and break down and lower set back value. When TPI, Vi/H and overall sensory eating score of cooked rices measured were divided into three categories, high, medium and low using deviation from locational mean value of a variety, many of rice samples having high TPI or high Vi/H showed medium or high in overall sensory eating score of cooked rice.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.147-151
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• 2014

This study was conducted to clarify the characteristics of amphibian and reptile (herpetofauna) populations in a coniferous plantation and a deciduous forest from July to September 2013 in national forest, Hongcheon, Gangwon province, Korea. Coverage of understory, mid-story and overstory were more developed in a deciduous forest. We used line transect sampling method on a total of 4 transect lines, 2 lines in each forest type. Fifty two individuals of 4 amphibian species and 11 individuals of 3 reptile species were recorded. Mean observed number of herpetofauna species, individuals and species diversity index (H') were not significantly different between coniferous plantation and deciduous forest. This result related to ecological characteristics of herpetofauna. Habitats of herpetofauna were influenced on not only vertical structure of forests, but also climatic variables, thermoregulation and prey availability. The long-term monitoring and research on habitat preference and seasonal ecological traits of herpetofauna would be needed for conservation and management of herpetofauna in forest areas.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.395-399
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• 2011

Material of the gasket for lithium ion battery requires the chemical resistance, the electrical insulting property, the compression set, the anti-contamination level and the low temperature resistance. We compounded ethylene propylene diene monomer (EPDM), which showed widely different solubility parameter index, with adjusting the amount of metal oxide as an activator. We did long-term test and compression set against an electrolyte with consideration for operating conditions in lithium-ion battery. In these tests, we checked the physical, chemical characteristics and the effect to lithium ion battery with different kinds of activators. In case of rubber with ZnO as an activator, through 1000 h depositing test in propylene carbonate which is one of representative solvents, we could get the satisfying characteristics and result. However, $Zn^{2+}$ had eluted in the ion elution test. So, ZnO should be limited in EPDM compound for the gasket material in lithium-ion battery.

• Phonetics and Speech Sciences
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• v.14 no.3
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• pp.87-101
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• 2022

In addition to administering a questionnaire (J-survey), which questions individuals on subjective vocal fatigue, voice samples were collected before and after speech-language pathology sessions from 50 female speech-language pathologists in their 20s and 30s in the Daejeon and Chungnam areas. We identified significant differences in Korean Vocal Fatigue Index scores between the fatigue and non-fatigue groups, with the most prominent differences in sections one and two. Regarding acoustic phonetic characteristics, both groups showed a pattern in which low-frequency band energy was relatively low, and high-frequency band energy was increased after the treatment sessions. This trend was well reflected in the low-to-high ratio of vowels, slope LTAS, energy in the third formant, and energy in the 4,000-8,000 Hz range. A difference between the groups was observed only in the vowel energy of the low-frequency band (0-4,000 Hz) before treatment, with the non-fatigue group having a higher value than the fatigue group. This characteristic could be interpreted as a result of voice abuse and higher muscle tonus caused by long-term voice work. The perturbation parameter and shimmer local was lowered in the non-fatigue group after treatment, and the noise-to-harmonics ratio (NHR) was lowered in both groups following treatment. The decrease in NHR and the fall of shimmer local could be attributed to vocal cord hypertension, but it could be concluded that the effective voice use of speech-language pathologists also contributed to this effect, especially in the non-fatigue group. In the case of the non-fatigue group, the rhamonics-to-noise ratio increased significantly after treatment, indicating that the harmonic structure was more stable after treatment.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.145-156
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• 2006

The objective of this study was to evaluate biological health conditions and physicochemical status using multi-metric models at five sites of the Keum-Ho River during August 2004 and June 2005. The research approach was based on a qualitative habitat evaluation index (QHEI), index of biological integrity (IBI) using fish assemblage, and long-term chemical data (1995 ${\sim}$ 2004), which was obtained from the Ministry of Environment, Korea. For the biological health assessments, regional model of the IBI in Korea (An,2003), was applied for this study. Mean IBI in the river was 30 and varied from 23 to 48 depending on the sampling sites. The river health was judged to be "fair condition", according to the stream health criteria of US EPA (1993) and Barbour et al. (1999). According to the analysis of the chemical water quality data of the river, BOD, COD, conductivity, TP, TN, and TSS largely varied epending on the sampling sites, seasons and years. Variabilities of some parameters including BOD, COD, TP, TN, and conductivity were greater in the downstream than in the upstream reach. This phenomenon was evident in the dilution by the rain during the monsoon. This indicates that precipitation is a very important factor of the chemical variations of water quality. Community analyses showed that species diversity index was highest (H=0.78) in the site 1, while community dominance index was highest in the site 3, where Opsariichthys uncirostris largely dominated. In contrast, the proportions of omnivore and tolerant species were greater in the downstream reach, than in the upstream reach. Overall, this study suggests that some sites in the downstream reach may need to restore the aquatic ecosystem for better biological health.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.882-889
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• 2022

In this study, to understand the factors influencing the flow change the Tsushima Warm Current (TWC), the correlation between the volume transport the TWC, El Niño Southern Oscillation (ENSO), and Pacific Decadal Oscillation (PDO) was analyzed. A calculation of the monthly volume transport of TWC for 25 years (1993-2018) revealed that the seasonal fluctuation cycle was the largest in summer and smallest in winter. Power spectrum analysis to determine the periodicity of the TWC volume transport, Oceanic Niño Undex (ONI), and PDO indicated that the TWC volume transport peaked at a one year cycle, but ONI and PDO showed no clear cycle. Further, to understand the correlation between the TWC transport volume and ONI and PDO, the coherence estimation method was used for analysis. The coherence of ONI and PDO had a high mutual contribution in long-period fluctuations of three years or more but had low mutual contribution in short-period fluctuations within one year. However, the coherence value between the two factors of the TWC volume transport and PDO was 0.7 in the 0.8-1.2 year cycle, which had a high mutual contribution. Meanwhile, the TWC volume transport and PDO have an inverse correlation between period I (1993-2002) and period III (2010-2018). When the TWC maximum transport volume (2.2 Sv or more) was high, the PDO index showed a negative value below -1.0, and the PDO index showed a positive value when the TWC maximum transport volume was (below 2.2 Sv). Therefore, using long-term PDO index data, changes in the TWC transport volume and water temperature in the East Sea coastal area could be predicted.

• Korean Journal of Environment and Ecology
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• v.29 no.6
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• pp.917-922
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• 2015

This study was carried out to investigate solutes concentration change with respect to discharge change in coniferous forest experiment watershed in Gyeonggi-do, Korea. From 2005 to 2008. Precipitation, discharge, solutes has been analyzed from 23 precipitation events. The results showed that low API induced low discharge. $NH_4{^+}$, $K^+$, and $Ca^{2+}$ were indicated by clockwise and $Cl^-$ and $NO_3{^-}$ were represented by counterclockwise hysteresis loop. ${SO_4}^{2-}$, $Na^+$, $Mg^{2+}$ showed no hysteresis loop pattern. $Cl^-$, $Na^+$, $NH_4{^+}$ was relatively constant due to groundwater during precipitation, $NO_3{^-}$ was increased due to soil water compared to early precipitation. $Cl^-$, ${SO_4}^{2-}$, $Na^+$, $Mg^{2+}$, $Ca^{2+}$ was diluted with respect to increased discharge and $NO_3{^-}$ was diluted in early precipitation and then increased in the end. $NO_3{^-}$ and $Ca^{2+}$ eluviated in early precipitation. This characteristics was presumed by the effect of API, discharge and ground water.