• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.3
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• pp.103-117
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• 2022

The recent corporate economy, such as the COVID 19 pandemic that has spread all over the world since the beginning of 2020, the acceleration of the 4th industrial revolution, and supply chain management risks triggered by the US-China conflict and the Ukraine crisis, is more serious than ever before. CEOs who have started and managed small and medium-sized enterprises (SMEs) are more concerned than ever about the sustainability of their businesses in this reality. Nevertheless, there were few empirical studies on the factors that influence the intention of SME CEOs to discontinue business. In this study, the perception of the business environment of SMEs (intensity of competition in key business areas, difficulty in manpower management), corporate competency (employee competency, company product or service competitiveness, supply chain and consumer relations, digital competency and technical expertise), and CEO's competency(trust between employees and the CEO, management competency and perceived health status of CEO) on CEO's intention to discontinue business was discussed. As a result of the study, the intensity of competition in the main business field, and the difficulty in manpower management had a positive (+) effect on the intention to discontinue the business, and the employee competency, product (service) competitiveness, digital competency of the company, and the CEO's Health status had a negative (-) effect on intention to discontinue business. The relationship between these influences was found in the order of CEO's health status, product competitiveness, employee competency, digital competency, competitive strength in the main business, and difficulty in manpower management. It was analyzed that supply chain and consumer relations, trust between employees and the CEO, and management capabilities did not significantly affect the intention to discontinue business. On the other hand, business confidence has a mediating effect between the intensity of competition in the main business field, the difficulty in manpower management, product or service competitiveness, digital competency, trust between employees and the CEO, and the management capability and intention to discontinue business was tested. This study had academic significance in that it empirically analyzed factors related to intention to discontinue business targeting small and medium-sized business CEOs. In practice, as it has been found that business environment awareness, corporate competency, managerial competency, and business confidence are factors that influence the intention to discontinue business, if an action ideas that can reinforce this part can be found, SMEs can achieve sustainable growth or it may help CEO find an meaningful exit.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.87-98
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• 2024

This study was conducted to investigate the efficiency of the filtering sets composed of fiberboards, which were fabricated with lignocellulosic fiber and cork oak bark-based activated carbon (COA), as well as traditional Korean paper handmade from mulberry trees (KP) for the filtration of PM, TVOC and HCHO. Three-layers fiberboards (WRF) were fabricated with wood fiber in its surface layers and recycled fiber/COA in its core layer using a protein-based adhesive with the resin content of 8%. Filtering sets were composed of three WRF and one sheet of KP. Concentrations of PM, TVOC and HCHO generated with the combustion of a incense in a sealed laboratory hood were reduced efficiently with the operation of air-purifier installed the filtering sets. Except for the WRF fabricated with 4%/4% resin contents, other WRF were prepared with 5%/3% and 6%/2% resin contents in surface/core layers, and then the WRF were used with KP for the fabrication of filtering sets. Filtration efficiency of the filtering sets was improved as the core-layer resin content applied in the fabrication of WRF decreased. In addition, filtration efficiency of the WRF-based filtering set fabricated with KP of 25 g/m² basis weight was higher than that with KP of 45 g/m² basis weight. Filtering sets composed of three-layers fiberboards (RWF) that recycled fiber and wood fiber/COA were used in its surface and core layers, respectively, and KP-25g showed higher filtration efficiency than those of WRF-based filtering sets. Air-inhalation equipment installed the RWF-based, WRF-based filtering sets and without filtering set were operated in small indoor and large outdoor spaces. Efficiency for filtering PM and TVOC of the RWF-based filtering sets was higher than that of other filtering sets. It is concluded that fiberboard-based filtering sets composed of RWF and KP-25g can be used as a filter for reducing the concentrations of PM and TVOC existed in indoor and outdoor spaces.

• Korean Journal of Environment and Ecology
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• v.38 no.2
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• pp.169-177
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• 2024

This study investigated whether population dynamic analysis based on the height characteristics of Abies nephrolepis was feasible. It was necessary because existing population dynamic analyses based on age and diameter at breast height (DBH) made it difficult to reflect the slow growth characteristics of Abies nephrolepis in harsh environments of high altitudes. The limitations of population dynamics analysis based on the age and DBH distribution of Abies nephrolepis in Seoraksan, Odaesan, and Taebaeksan National Parks, where Abies nephrolepis populations are representative, were verified, and the characteristics of height growth were investigated to comprehensively analyze whether a vertical structure based on height could reveal the population dynamics. The result of this study showed some limitations in understanding the population dynamics of Abies nephrolepis based on age distribution due to practical difficulties in sampling all trees and variations in age distribution within the same community depending on factors such as light conditions. Moreover, it was challenging to differentiate the distribution of DBH classes at fine levels, making it difficult to reflect the rapid growth characteristics of Abies nephrolepis when light conditions become suitable after prolonged stays in smaller DBH classes under shade conditions. However, a comprehensive analysis of the height characteristics of Abies nephrolepis revealed that the density corresponding to the population dynamic characteristics of Abies was high and adequately reflected the predominant tree death at similar height stages, as well as the U-shaped population dynamics at the lower stratum. Moreover, it was possible to identify a transition point in height values under shaded conditions, where the annual growth of Abies nephrolepis individuals in the lower stratum increases significantly, indicating that Abies nephrolepis individuals can escape from competition with other shrubs and undergo vigorous growth only at this height level. Therefore, this study confirmed that a vertical structure based on height can be utilized to understand the population dynamics of Abies nephrolepis in high altitudes, and it is expected that future studies on height characteristics can intuitively reveal the maintenance status of Abies nephrolepis populations in the field.

• Journal of Food Hygiene and Safety
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• v.39 no.2
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• pp.109-117
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• 2024

This study investigated the microbial contamination of agricultural, livestock, and marine ingredients in 55 meal kits distributed across Gyeonggi-do, South Korea. Of the 55 meal kits, 48 contained agricultural ingredients, 43 contained livestock ingredients, and 16 contained marine ingredients. The detection rate of the total aerobic bacteria in the agricultural, livestock, and marine products was 100%. The average numbers of the total aerobic bacteria were 6.57 log colony-forming units (CFU)/g in the agricultural products, 4.60 log CFU/g in the livestock products, and 5.47 log CFU/g in the marine products. The coliform detection rates in the agricultural, livestock, and marine products were 81.25%, 69.77%, and 43.75%, respectively. The average numbers of coliforms were 2.83 log CFU/g in the agricultural products, 1.34 log CFU/g in the livestock products, and 1.12 log CFU/g in the marine products. Escherichia coli was detected in 13 livestock products (30.23%), with levels ranging from 0.70 to 2.36 log CFU/g. Contrastingly, E. coli was detected in only one marine product (6.25%) and was not detected in any agricultural products. The detection rates of fungi in agricultural, livestock, and marine products were 97.92%, 93.02%, and 93.75%, respectively. The average numbers of fungi were 3.82 log CFU/g for the agricultural products, 2.92 log CFU/g for the livestock products, and 2.82 log CFU/g for the marine products. The isolation rates of foodborne pathogens from the agricultural, livestock, and marine products were 35.42%, 37.21%, and 31.25%, respectively. Forty-five foodborne pathogens of seven species, including Bacillus cereus and Salmonella spp., were isolated from the raw materials of the agricultural, livestock, and marine products in 55 meal kits. To prevent foodborne diseases caused by meal kits, it is necessary to focus on washing, heating, and preventing cross-contamination during cooking.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.4
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• pp.51-58
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• 2023

In this study, anaerobic co-digestion was carried out using desulfurization sludge and sewage sludge (primary sludge) to evaluate the effects of sulfur compounds in anaerobic digestion. The experiment was carried out in the form of a batch test using 500 mL duran bottle, and the mixing ratio of the feedstock was selected based on the ratio of COD/SO₄. As a result of the experiment, it was confirmed that the amount of biogas generated and the yield decreased at the mixing ratio of COD/SO₄ 20 or less. In particular, below COD/SO₄ 10, it was lower than seed (283.5 mL) which was set without feedstock to correct biogas generated by itself from seed sludge. Methane yield tended to decrease from a ratio of COD/SO₄ 20 or less to 0.135 m³/kg VS compared to 0.396 m³/kg VS of COD/SO₄ 50. In addition, compared to 0.0097 m³/kg VS of hydrogen sulfide yield from COD/SO₄ 50, the ratio of COD/SO₄ 20 increased sharply to 0.0223 m³/kg VS, and in particular, the highest result was 0.0855 m³/kg VS in COD/SO₄ 10. Based on these results, it is judged that the effect of sulfide in anaerobic digestion can have an adverse effect if the COD/SO₄ ratio decreases to less than 20.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.6
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• pp.583-603
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• 2023

Recently, the advancement of mechanical tunnel boring machine (TBM) technology and the characteristics of subsea railway tunnels subjected to hydrostatic pressure have led to the widespread application of shield TBM methods in the design and construction of subsea railway tunnels. Subsea railway tunnels are exposed in a constant pore water pressure and are influenced by the amplification of seismic waves during earthquake. In particular, seismic loads acting on subsea railway tunnels under various ground conditions such as soft ground, soft soil-rock composite ground, and fractured zones can cause significant changes in tunnel displacement and stress, thereby affecting tunnel safety. Additionally, the dynamic response of the ground and tunnel varies based on seismic load parameters such as frequency characteristics, seismic waveform, and peak acceleration, adding complexity to the behavior of the ground-tunnel structure system. In this study, a finite difference method is employed to model the entire ground-tunnel structure system, considering hydrostatic pressure, for the investigation of dynamic behavior of subsea railway tunnel during earthquake. Since the key factors influencing the dynamic behavior during seismic events are ground conditions and seismic waves, six analysis cases are established based on virtual ground conditions: Case-1 with weathered soil, Case-2 with hard rock, Case-3 with a composite ground of soil and hard rock in the tunnel longitudinal direction, Case-4 with the tunnel passing through a narrow fault zone, Case-5 with a composite ground of soft soil and hard rock in the tunnel longitudinal direction, and Case-6 with the tunnel passing through a wide fractured zone. As a result, horizontal displacements due to earthquakes tend to increase with an increase in ground stiffness, however, the displacements tend to be restrained due to the confining effects of the ground and the rigid shield segments. On the contrary, peak compressive stress of segment significantly increases with weaker ground stiffness and the effects of displacement restrain contribute the increase of peak compressive stress of segment.

• Food Science and Preservation
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• v.30 no.1
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• pp.78-87
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• 2023

This study was conducted to evaluate the effect of different 1-methylcyclopropene (1-MCP) concentrations on fruit quality of small-sized RubyS apples during cold storage. After harvesting, the fruits were treated with 1-MCP at 0.5 or 1 µL/L concentrations and, subsequently, stored at 0℃ for 6 months. After 6 months, the flesh firmness of untreated fruits, which was 85.4 N at harvest, had gradually decreased to 46.5 N; however, that of 1-MCP-treated fruits was maintained at 59.1 and 59.5 N. Titratable acidity (TA) of untreated fruits had also decreased from 0.42 to 0.24%, whereas that of 1-MCP-treated fruits was maintained at 0.26 and 0.27%. Soluble solids content (SSC) did not differ in all fruits. However, the 1-MCP-treated fruits had lower levels of SSC/TA ratio than untreated fruits. Moreover, after 6 months, the ethylene production had increased to 47.0 µL/kg/h in the untreated fruits, whereas 1-MCP blocked the ethylene production at 1.4 and 1.7 µL/kg/h. The weight loss and peel color variables remained unaffected by 1-MCP treatments. Thus, these results indicated that, for RubyS apples, the storability was only 2 months at 0℃ without treatment, which can be extended to 6 months with 1-MCP treatments. The application of 1-MCP at 0.5 µL/L concentration is effectively and economically sufficient to maintain the quality of RubyS apples.

• Food Science and Preservation
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• v.30 no.1
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• pp.109-121
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• 2023

This study was conducted to evaluate vitamin D intake of Koreans in a total diet study (TDS) and to determine the effect of irradiation on vitamin D synthesis in mushrooms. For analysis, sample were saponified and extracted with hexane, and vitamin D was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Based on the validation results, the recovery of the National Institute of Standards and Technology (NIST) standard reference sample (SRM) 1849a was 96.7% and the z-score of -1.6 was obtained by the Food Analysis Performance Assessment Scheme (FAPAS) proficiency test (PT) 21115. Vitamin D₂ was not detected in any samples, and the highest level of vitamin D₃ was detected in mackerel and anchovies ranging from 24.2 to 120.2 ㎍/kg. The mean daily intake of vitamin D was 0.99 ㎍/day, as estimated from the vitamin D contents of the analyzed foods and their corresponding intake. The adequate intake (AI) of vitamin D based on the Dietary reference intakes for Koreans provided by the Ministry of Health and Welfare is 5-15 ㎍/day for Koreans aged 6 to 75 years. Compared with this AI, vitamin D intake of Koreans estimated in this study was inadequate. For that, the increased vitamin D content in ultraviolet (UV)/sun light irradiated mushrooms warrants further research to increase vitamin D intake of Koreans through diet.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.1-7
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• 2024

Mn-M/Al₂O₃ (M = Cu, Fe, Co, and Ce) catalysts were prepared for simultaneous oxidation of NO, CO, and CH₄, and their oxidation activities were compared. The Mn-Cu/ Al₂O₃ catalyst with the best simultaneous oxidation activity was characterized by XRD, Raman, XPS, and O₂-TPD analysis. The result of XRD indicated that Mn and Cu existed as complex oxides in the Mn-Cu/Al₂O₃ catalyst. Raman and XPS results showed that electron transfer between Mn ions and Cu ions occurred during the formation of the Mn-O-Cu bond in the Mn-Cu/Al₂O₃ catalyst. The XPS O 1s and O₂-TPD analyses showed that the Mn-Cu/Al₂O₃ catalyst has more adsorbed oxygen species with high mobility than the Mn/Al₂O₃ catalyst. The high simultaneous oxidation activity of the Mn-Cu/Al₂O₃ catalyst is attributed to these results. Gas-phase NO promotes the oxidation reactions of CO and CH₄ in the Mn-Cu/Al₂O₃ catalyst while suppressing the NO oxidation reaction. These results were presumed to be because the oxidized NO was used as an oxidizing agent for CO and CH₄. On the other hand, the oxidation reactions of CO and CH₄ competed on the Mn-Cu/Al₂O₃ catalyst, but the effect was not noticeable because the catalyst activation temperature was different.

• Food Science and Preservation
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• v.31 no.2
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• pp.315-323
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• 2024

This study aims to confirm the anti-inflammatory activities of acemannan and aloesin, which have been studied for various efficacies at various mixed sample ratios. The mixed samples were mixed at a ratio of 1:1 (AA-1), 1:2 (AA-2), 1:3 (AA-3), 2:1 (AA-4), and 3:1 (AA-5). Seven samples were evaluated for their cytotoxic ability on macrophages, and the results showed that all cell viability was over 90% at a concentration of 100 ㎍/mL. First, due to the NO production inhibitory activity, a better inhibitory effect was achieved when using a mixed sample rather than a single material. Afterward, the activity of inhibiting the production of PGE₂, TNF-α, and IL-6 was confirmed using a mixed sample. It was confirmed that AA-2 had the best inhibitory activity on producing PGE2, TNF-α, and IL-6 rather than AA-1, AA-3, AA-4, and AA-5. For this reason, experiments were conducted using AA-2 to determine the protein expression levels of iNOS and COX-2, which are inflammation-related proteins. It was confirmed that AA-2 inhibited iNOS and COX-2 protein expression by 25.01% and 27.27%, respectively, compared to the LPS-alone treatment group. In conclusion, the mixed sample of acemannan and aloesin is judged to have anti-inflammatory activity and can potentially to be used as a functional material.