• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.293-299
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• 2012

The thermodynamic efficiency characteristics of R245fa and water as working fluids have been analyzed for the electricity generation system applying the Rankine cycle to recover the waste heat of the exhaust gas from a diesel engine for the propulsion of a large ship. The theoretical calculation results showed that the cycle, system, and total efficiencies were improved as the turbine inlet pressure was increased for R245fa at a fixed mass flow rate. In addition, the net work rate generated by the Rankine cycle was elevated with increasing turbine inlet pressure. In the case of water, however, the maximum system efficiencies were demonstrated at relatively small ratios of mass flow rate and turbine inlet pressure, respectively, compared to those of R245fa. The optimized values of the net power of the cycle, system efficiency, and total efficiency for water had relatively large values compared to those of R245fa.

• Journal of the Korean Professional Engineers Association
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• v.24 no.6
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• pp.97-105
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• 1991

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill ø70mm on the calcalious sand stone (soft-moderate-semi hard Rock). The total numbers of fire blast were 88 round. Scale distance were induces 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagation Law in Blasting Vibration (Equation omitted) where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W : Maximum Charge per delay-period of eighit milliseconds o. more(kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents Where the quantity D / W$^n$ is known as the Scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagrorized in three graups. Cubic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge per delay Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom and over 100m distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30 ‥‥‥under 100m ‥‥‥V=41(D/$^3$√W)$\^$-1.41/ ‥‥‥A Over 100 ‥‥‥‥under 100m ‥‥‥V=121(D/$^3$√W)$\^$-1.56/ ‥‥‥B K value on the above equation has to be more specified for furthur understang about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• The Journal of the Acoustical Society of Korea
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• v.14 no.1
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• pp.73-80
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• 1995

In this paper, Polarity Thresholding(PT) algorithm has been studied to enhance the received signal in ultrasonic inspection of the stainless-steel(SUS 304) which is the primary piping material of a nuclear power plant. The spectral decomposition components obtained by splitting the spectrum of received signals are composed of dispersive signal of the interference pattern produced by the grain boundaries and nondispersive signal by the flaw. PT algorithm enhance the SNR of received signal by using above properties. In experiment the stainless-steel has been chosen as the sample and heat-treated at 1125, 1150, 1175, and $1200^\circ{C}$, respectively. And the flat-bottom hole type defects have been made artificially in samples. The pulse-echo signals from the sample by using ultrasonic transducer of center frequency 5 MHz have been processed by PT algorithm. It has been shown that PT algorithm enhanced the SNR by average 14.2 dB.

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.109-114
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• 2014

After the Fukushima accident in 2011, it was revealed that nuclear power plant has the vulnerability to SBO accident and its extension situation without sufficient cooling of reactor core resulting core meltdown and radioactive material release even after reactor shutdown. Many safety systems had been developed like PAFS, hybrid SIT, and relocation of RPV and IRWST as a part of steps for the Fukushima accident, however, their applications have limitation in the situation that supply of feedwater into reactor is impossible due to high pressure inside reactor pressure vessel. The concept of hybrid heat pipe with control rod is introduced for breaking through the limitation. Hybrid heat pipe with control rod is the passive decay heat removal system in core, which has the abilities of reactor shutdown as control rod as well as decay heat removal as heat pipe. For evaluating the cooling performance hybrid heat pipe, a commercial CFD code, ANSYS-CFX was used. First, for validating CFD results, numerical results and experimental results with same geometry and fluid conditions were compared to a tube type heat pipe resulting in a resonable agreement between them. After that, wall temperature and thermal resistances of 2 design concepts of hybrid heat pipe were analyzed about various heat inputs. For unit length, hybrid heat pipe with a tube type of $B_4C$ pellet has a decreasing tendency of thermal resistance, on the other hand, hybrid heat pipe with an annular type $B_4C$ pellet has an increasing tendency as heat input increases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.11
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• pp.3516-3524
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• 1996

Service conditions for structures at elevated temperatures in nuclear power plant involve transient thermal and mechanical load levels that are severe enough to caeuse inelastic deformations due to creep and plasticity. Therefore, a systematic mehtod of inelastic analysis is needed for the design of structural components in nuclear poser plants subjected to such loading conditions. In the present investigation, the Chabodhe model, one of the unified viscoplastic constitutive equations, was selected for systematic inelastic analysis. The material response was integrated based on GMR ( generallized mid-point rule) time integral scheme and provided to ABAQUS as a material subroutine, UMAT program. By comparing results obtaned from uniaxial analysis using the developed UMAT program with those from Runge-Kutta solutions and experimentaiton, the validity of the adopted Chaboche model and the numerical stability and accuracy of the developed UMAT program were verified. In addition, the developed material subroutine was applied for uniaxial creep and tension analyses for the plate with a hole in the center. The application further demonstrates usefulness of the developed program.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.5
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• pp.43-50
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• 2008

DLN-2.6 combustion tuning was carried out for the maintenance of GE 7FA+e gas turbine at Seo-Incheon combined cycle power plant. DLN-2.6 combustion system has the higher level of yellow plume and combustion vibration problem in the initial operating mode than that of the base mode($100{\sim}160MW$). The objectives of this study are to investigate the causes of yellow plume and combustion vibration problems at the starting mode and to suggest the best operating condition for the reliable working of the real combustors. By the analysis of tuning data, we could conclude that a yellow plume is caused by the rich mixture(${\phi}{\sim}1$) in a PM 1 nozzle at mode 3($20{\sim}30MW$). In addition, the combustion vibration($120{\sim}140Hz$) might be related to the cold flow characteristics of PM 3 nozzles at mode 6B($40{\sim}45MW$).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.4
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• pp.567-578
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• 2002

The main purpose of this study is to investigate the dynamic behaviour of containment building in nuclear power plant excited by aircraft impact loading using a lower order 8-node solid element. The yield and failure surfaces for concrete material model is formulated on the basis of Drucker-Prager yield criteria and are assumed to be varied by taking account of the visco-plastic energy dissipation. The standard 8-node solid element has prone to exhibit the element deficiencies and the so-called B bar method proposed by Hughes is therefore adopted in this study. The implicit Newmark method is adopted to ensure the numerical stability during the analysis. Finally, the effect of different levels of cracking strain and several types of aircraft loading are examined on the dynamic behaviour of containment building and the results are quantitatively summarized as a future benchmark.

• Journal of Microbiology and Biotechnology
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• v.30 no.12
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• pp.1927-1936
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• 2020

Tunicates are known to contain biologically active materials and one species in particular, the sea peach (Halocynthia aurantium), has not been thoroughly studied. In this study we aimed to analyze the fatty acids profile of the H. aurantium body wall and its immunomodulatory effects on RAW264.7 macrophage-like cells. The fatty acids were classified into three categories: saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs). Omega-3 fatty acid content, including EPA and DHA, was higher than omega-6 fatty acids. H. aurantium body wall fatty acids exhibited enhanced immune response and anti-inflammatory effects on RAW264.7 macrophage-like cells. Under normal conditions, fatty acids significantly increase nitric oxide (NO) and PGE2 production in a dose-dependent manner, thereby improving the immune response. On the other hand, in LPS-treated RAW264.7 cells, fatty acids significantly decreased nitric oxide (NO) and PGE2 production in a dose-dependent manner, thereby enhancing anti-inflammatory effects. Fatty acids transcriptionally control the expression of the immune-associated genes, iNOS, IL-1β, IL-6, COX-2, and TNF-α, via the MAPK and NF-κB signaling cascades in RAW264.7 cells. However, in LPS-stimulated RAW264.7 cells, H. aurantium body wall fatty acids significantly inhibited expression of inflammatory cytokine; similarly, production of COX-2 and PGE2 was inhibited. The results of our present study provide insight into the immune-improving and anti-inflammatory effects of H. aurantium body wall fatty acids on macrophages. In addition, our study demonstrates that H. aurantium body wall is a potential source of immune regulatory components.

• Journal of Nutrition and Health
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• v.56 no.5
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• pp.455-468
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• 2023

Purpose: Abeliophyllum distichum (A.distichum) is a plant native to Korea. In this study, we investigated the mechanism of antioxidant and anti-inflammatory effects of the leaf extract of A.distichum. Methods: The antioxidant capacity of the A.distichum leaf extract was determined based on the total polyphenol content, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay, and the ferric reducing antioxidant power (FRAP) assay. The anti-inflammatory effects of the A.distichum leaf extract were evaluated by measuring the production of nitric oxide (NO) and the expression levels of proinflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 using the enzyme-linked immunosorbent assay (ELISA) and reverse transcription quantitative real-time PCR (RT-qPCR). In addition, the expression of heme oxygenase-1 (HO-1), nuclear transcription factor-erythroid 2 related factor (Nrf2), inducible nitric oxide synthase (iNOS), and cyclooxygenase 2 (COX-2), as well as the activation of nuclear factorkappa B (NF-ĸB) were examined using the western blot analysis. Results: The total polyphenol content of the A.distichum leaf extract was 329.89 ± 30.17 gallic acid equivalents mg/g and the DPPH and ABTS scavenging activities were 55% and 70%, respectively. Additionally, the FRAP value of the extract was 743.68 ± 116.59 mg/mL. After 12-hour treatment with the A.distichum leaf extract, there was a tendency for the Nrf2 expression to increase, and the expression of HO-1 was significantly elevated in the RAW264.7 cells. The A.distichum leaf extract treatment resulted in decreased levels of NO, TNF-α, IL-6, and IL-1β, as well as reduced expression of iNOS and COX-2, along with inhibition of NF-κB activation in lipopolysaccharide-stimulated RAW264.7 cells. Conclusion: These results suggest that the A.distichum leaf extract exerts antioxidative and anti-inflammatory effects by upregulating the expression of HO-1 and downregulating NF-κB activation.

• Korean Journal of Plant Resources
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• v.36 no.1
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• pp.15-25
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• 2023

Myriophyllum spicatum L. has been used as an ornamental in ponds and aquariums, and as a folk remedy for inflammation and pus. Nevertheless, the biological activity and underlying mechanisms of anti-inflammatory effects are unclear. This study is aimed at investigating the antioxidative and anti-inflammatory activities of ethanol extract of Myriophyllum spicatum L. (EMS) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Antioxidant activity of EMS was assessed by radical-scavenging effects on ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. As inflammatory response parameters produced by LPS-stimulated RAW 264.7 cells were quantified to assess the anti-inflammatory activity of EMS. Our results showed that EMS increased FRAP and DPPH radical-scavenging activity. In EMS-treated RAW 264.7 cells, the production of NO, PGE₂, TNF-α and IL-1β was significantly inhibited at the non-cytotoxic concentration. In addition, EMS significantly attenuated LPS-stimulated the toll-like receptor (TLR) 4/myeloid differentiation protein (MyD) 88 signaling pathway, and inhibited nuclear translocation of nuclear factor-kappa B(NF-κB). Positive correlations were noted between anti-inflammatory activity and antioxidant activity. In conclusion, it was indicated that EMS suppresses the transcription of inflammatory factors by inhibiting the TLR4/MyD88/NF-κB signaling pathway, thereby suppressing LPS-stimulated inflammation in RAW 264.7 cells. This study highlights the potential role of EMS against inflammation and associated diseases.