• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.167-167
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• 2018

• Journal of the Society of Naval Architects of Korea
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• v.61 no.2
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• pp.135-142
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• 2024

There is a lot of concern around the world about air pollution from ships. The majority of air pollution from ships comes from fuel combustion. The combustion process produces various air pollutants such as carbon monoxide (CO), carbon dioxide (CO₂), nitrogen oxides (NOx), sulfur oxides (SOx), and particulate matter (PM), each of which has adverse effects on people and is a major environmental problem. To prevent this, the International Maritime Organization (IMO) has strengthened the regulation of pollutant emissions through the Convention for the Prevention of Marine Pollution. This paper discusses the types of air pollutants emitted by ships, their current status, and the latest technologies to reduce emissions of NOx and SOx.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.3
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• pp.186-192
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• 2023

According to the regulation on the pollution of the marine environment, SOx emission from ships has to be reduced. A SOx scrubbing system installed in a funnel of a ship is considered in order to reduce SOx emission. A scrubbing layer with a porous material is present in the funnel to increase the contact area between exhaust gas and water. In this study, experiments on the pressure drop characteristics in the scrubbing layer are conducted to investigate the effect of the scrubber on the engine load. The pressure drop according to flow rate of air instead of exhaust gas was measured for fillers such as sphere, pall ring and saddle in the scrubbing layer. First of all, porosity is experimentally measured for the three types of filler and it is confirmed that the porosity of the saddle-type filler was the largest. The pressure drop according to the change in air flow rate was measured for the three types of fillers in the scrubbing layer. As a result, the pressure drop was the smallest in the scrubbing layer with the saddle-type filler which has the largest porosity. In addition, the effect of spraying water flowing counter flow against air flow is experimentally examined. It is known that the pressure drop is increased because the air flow space is reduced when water is sprayed. In the case of the saddle, the pressure drop is about 1.5 to 2 times greater than that when only air flows at the optimum exhaust gas-water injection ratio.

• Journal of Korea Port Economic Association
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• v.39 no.3
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• pp.107-122
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• 2023

This study aims to analyze the effect of reducing air pollutant emissions of the ship fuel oil sulfur content regulation policy, which has been gradually introduced for three years. In addition, the emission reduction effect of VSR and AMP was also analyzed. The analysis was conducted on NOx, CO, VOC, SOx, TSP, PM10, and PM2.5, which are provided by EEA, and the spatial scope of the analysis was conducted on Incheon Port, which is located in the metropolitan area of Korea and has a large ripple effect on air pollution. Three scenarios were constructed for analysis. Scenario 1: If there is no policy, Scenario 2: If only fuel oil sulfur content regulation was implemented, Scenario 3: The analysis was conducted by reflecting fuel oil sulfur content regulation, VSR, and AMP. As a result of the analysis, in the case of scenario 1, 4,801 tons, 4,932 tons, and 5,144 tons of air pollutants were emitted during the three-year period. In Scenario 2, 4,219 tons, 4,152 tons, and 3,989 tons were discharged, and in Scenario 3, 4,198 tons, 4,138 tons, and 3,973 tons were discharged. The findings of this study are anticipated to be applied as fundamental research in port air environment management and Incheon Metropolitan City air management.

• Development and Reproduction
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• v.15 no.1
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• pp.25-30
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• 2011

Embryonic stem (ES) cells can self-renew maintaining the undifferentiated state. Self renewal requires many factors such as Oct4, Sox2, FoxD3, and Nanog. NF-${\kappa}B$ is a transcription factor involved in many biological activities. Expression and activity of NF-${\kappa}B$ increase upon differentiation of ES cells. Reportedly, Nanog protein directly binds to NF-${\kappa}B$ protein and inhibits its activity in ES cells. Here, we found a potential binding site of NF-${\kappa}B$ in the human Nanog promoter and postulated that NF-${\kappa}B$ protein may regulate expression of the Nanog gene. We used human embryonic carcinoma (EC) cells as a model system of ES cells and confirmed decrease of Nanog and increase of NF-${\kappa}B$ upon differentiation induced by retinoic acid. Although deletion analysis on the DNA fragment including NF-${\kappa}B$ binding site suggested involvement of NF-${\kappa}B$ in the negative regulation of the promoter, site-directed mutation of NF-${\kappa}B$ binding site had no effect on the Nanog promoter activity. Furthermore, no direct association of NF-${\kappa}B$ with the Nanog promoter was detected during differentiation. Therefore, we conclude that NF-${\kappa}B$ protein may not be involved in transcriptional regulation of Nanog gene expression in EC cells and possibly in ES cells.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.115-116
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• 2006

보다 깨끗한 환경에서 살고 싶어 하는 인류의 욕구가 육상의 대기 배출물뿐만 아니라 선박까지도 보다 깨끗한 배기를 요구하기에 이르렀다. 이러한 요구에 부응하여 IMO(국제해사기구)뿐만 아니라 EU(유럽연합)과 미국 등에서 규제를 이미 시작하였거나 시작할 예정이다. 또한 많은 선급에서도 약 10년 전부터 자발적인 규칙을 도입해오고 있다. 그리고 스웨덴은 인센티브제를 오래 전부터 적용해오고 있다. 이러한 규제, 선급 규칙 및 인센티브제는 질소산화물, 황산화물 및 입자상물질 배출에 제한을 가하는데, 황산화물 및 입자상물질 배출 제한은 간접적으로 연료유에 함유되어 있는 황 함량 규제를 통하여 하고 있거나 하려고 한다. 여기에 이러한 규제, 선급 규칙 및 인센티브제에서 가하고 있거나 가할 예정인 선박 디젤기관 연료유의 황 함량 규제에 대하여 간략하게 소개한다.

• Prospectives of Industrial Chemistry
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• v.22 no.5
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• pp.41-50
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• 2019

2020년 1월 1일부터 이행되는 연료유의 황 함유량 규제에 따른 대응 현황을 보면, 약 60% 이상의 선사들이 저유황유 사용을 고려하고 있다. 이처럼 높은 저유황유 선택에 따라 저유황유의 안정적인 공급에 대한 사전 검토 및 대비책을 통한 구체적인 방안이 요구되고 있으며, 저유황유의 품질 보증이 무엇보다도 중요한 사안이라 판단된다. 저유황유의 품질에 따라 예상되는 문제점을 미리 파악하고 이에 대한 적절한 대응 방안을 수립하여 선박 기관 운영에 차질이 없도록 대비하여야 한다. 그래서 선박에 공급되는 저유황유의 품질 특성 시 고려사항을 전달하고자 한다.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1605-1612
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• 2016

Quinolone-resistant Salmonella strains were isolated from patient samples, and several quinolone-sensitive strains were used to analyze mutations in the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, and parE and to screen for plasmid-mediated quinolone resistance. Among the 21 strains that showed resistance to nalidixic acid and ciprofloxacin (MIC 0.125-2.0 μg/ml), 17 strains had a mutation in QRDR codon 87 of gyrA, and 3 strains had a single mutation (Ser83 → Phe). Another cause of resistance, efflux pump regulation, was studied by examining the expression of acrB, ramA, marA, and soxS. Five strains, including Sal-KH1 and Sal-KH2, showed no increase in relative expression in an analysis using the qRT-PCR method (p < 0.05). In order to determine the genes involved in the resistance, the Sal-9 isolate that showed decreased susceptibility and did not contain a mutation in the gyrA QRDR was used to make the STM (MIC 8 μg/ml) and STH (MIC 16 μg/ml) ciprofloxacin-resistant mutants. The gyrA QRDR Asp87 → Gly mutation was identified in both the STM and STH mutants by mutation analysis. qRT-PCR analysis of the efflux transporter acrB of the AcrAB-TolC efflux system showed increased expression levels in both the STM (1.79-fold) and STH (2.0-fold) mutants. In addition, the expression of the transcriptional regulator marA was increased in both the STM (6.35-fold) and STH (21.73-fold) mutants. Moreover, the expression of soxS was increased in the STM (3.41-fold) and STH (10.05-fold) mutants (p < 0.05). Therefore, these results indicate that AcrAB-TolC efflux pump activity and the target site mutation in gyrA are involved in quinolone resistance.

• Journal of Ginseng Research
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• v.43 no.3
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• pp.421-430
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• 2019

Background: The ginsenoside Rg3, one of active components of red ginseng, has chemopreventive and anticancer potential. Cancer stem cells retain self-renewal properties which account for cancer recurrence and resistance to anticancer therapy. In our present study, we investigated whether the standardized Korean Red Ginseng extract (RGE) and Rg3 could modulate the manifestation of breast cancer stem cell-like features through regulation of self-renewal activity. Methods: The effects of RGE and Rg3 on the proportion of $CD44^{high}/CD24^{low}$ cells, as representative characteristics of stem-like breast cancer cells, were determined by flow cytometry. The mammosphere formation assay was performed to assess self-renewal capacities of breast cancer cells. Aldehyde dehydrogenase activity of MCF-7 mammospheres was measured by the ALDEFLUOR assay. The expression levels of Sox-2, Bmi-1, and P-Akt and the nuclear localization of hypoxia inducible $factor-1{\alpha}$ in MCF-7 mammospheres were verified by immunoblot analysis. Results: Both RGE and Rg3 decreased the viability of breast cancer cells and significantly reduced the populations of $CD44^{high}/CD24^{low}$ in MDA-MB-231 cells. RGE and Rg3 treatment attenuated the expression of Sox-2 and Bmi-1 by inhibiting the nuclear localization of hypoxia inducible $factor-1{\alpha}$ in MCF-7 mammospheres. Suppression of the manifestation of breast cancer stem cell-like properties by Rg3 was mediated through the blockade of Akt-mediated self-renewal signaling. Conclusion: This study suggests that Rg3 has a therapeutic potential targeting breast cancer stem cells.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.237-242
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• 2021

Simultaneous removal technologies of multi-pollutants such as particulate matters (PMs), NOx, SOx, VOCs and ammonia have received consistent attention due to the enhancement of pollutant abatement efficiency in addition to the stringent environmental regulation and emission standard. Pretreatment of insoluble NO by an ozone oxidation can be considered to be more effective route for saving space occupation as well as operation cost in comparison with that of traditional selective catalytic reduction (SCR) process. Moreover the primary advantage of ozone oxidation process is that the simultaneous removal with acidic gas including SOx is also available. Herein, we highlight recent studies of multi-pollutant abatement via ozone oxidation process and the promising research topics for better application in industrial sectors.