• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.6
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• pp.306-318
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• 2018

In order to evaluate the seismic capacity of massive vertical type breakwaters which have intensively been deployed along the coast of South Korea over the last two decades, we carry out the preliminary numerical simulation against the PoHang, GyeongJu, Hachinohe 1, Hachinohe 2, Ofunato, and artificial seismic waves based on the measured time series of ground acceleration. Numerical result shows that significant sliding can be resulted in once non-negligible portion of seismic energy is shifted toward the longer period during its propagation process toward the ground surface in a form of shear wave. It is well known that during these propagation process, shear waves due to the seismic activity would be amplified, and non-negligible portion of seismic energy be shifted toward the longer period. Among these, the shift of seismic energy toward the longer period is induced by the viscosity and internal friction intrinsic in the soil. On the other hand, the amplification of shear waves can be attributed to the fact that the shear modulus is getting smaller toward the ground surface following the descending effective stress toward the ground surface. And the weakened intensity of soil as the number of attacking shear waves are accumulated can also contribute these phenomenon (Das, 1993). In this rationale, we constitute the numerical model using the model by Hardin and Drnevich (1972) for the weakened shear modulus as shear waves go on, and shear wave equation, in the numerical integration of which $Newmark-{\beta}$ method and Modified Newton-Raphson method are evoked to take nonlinear stress-strain relationship into account. It is shown that the numerical model proposed in this study could duplicate the well known features of seismic shear waves such as that a great deal of probability mass is shifted toward the larger amplitude and longer period when shear waves propagate toward the ground surface.

• Journal of Life Science
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• v.31 no.5
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• pp.488-495
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• 2021

The aim of this study was to investigate the possible antioxidant effect of Spirodela polyrhiza (SP) on rats fed a high fat and high cholesterol diet supplemented with either 5% (SPA group) or 10% (SPB group) SP for 4 weeks. The hepatic SOD activity of the HF group significantly decreased compared to that of the N group, but that of the SPA and SPB groups significantly increased. The GPx activity of the SPA and SPB groups in the liver was significantly greater than that of the HF group, and the hepatic catalase activity of the SPA and SPB groups significantly increased compared to the HF group. The hepatic superoxide radical content of the mitochondria and microsomes of the HF group significantly increased compared to that of the N group, but the contents were reduced in the group that took SP powder. The hepatic hydrogen peroxide content in the cytosol and mitochondria of the SP powder group was lower than in the HF group. The carbonyl content in the mitochondria and microsomes of the SPA and SPB groups was significantly lower than in the HF group. The TBARS values in the liver significantly decreased in the SPA and SPB groups. Spirodela polyrhiza was thus effective in reducing oxidative stress by regulating the hepatic antioxidant enzymes and the free radicals in rats fed high fat and high cholesterol diets.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.3
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• pp.145-154
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• 2022

Due to abnormal weather conditions caused by climate change, natural disasters and damages are gradually increasing around the world. Global climate change as accompanied by warming is projected to exert adverse impact on production of potato, which is known as cool season crop. Even though, role of potato as a food security crop is expected to increase in the future, the climate change impacts on potato and adaption strategies are not sufficiently established. Therefore, this study was conducted to analyze the damage pattern of potatoes due to high temperature treatment and to evaluate the response of cultivars. T he high temperature treatment (35~38℃) induced heat stress by sealing the plastic house in midsummer (July), and the quantity and quality characteristics of potatoes were compared with the control group. T otal yield, marketable yield (>80 g) and the number of tubers per plants decreased when heat treatment was performed, and statistical significance was evident. In the heat treatment, 'Jayoung' cultivar suffered a high heat damage with an 84% reduction in yield of >80 g compared to the control group. However, in Jopung cultivar, the decrease was relatively small at 26%. Tuber physiological disturbances (Secondary growth, Tuber cracking, Malformation) tended to increase in the heat stress. Under heat conditions, the tubers were elongated overall, which means that the marketability of potatoes was lowered. T he tuber firmness and dry matter content tended to decrease significantly in the heat-treated group. T herefore, the yield and quality of tubers were damaged when growing potatoes in heat conditions. T he cultivar with high heat adaptability was 'Jopung'. T his result can be used as basic data for potato growers and breeding of heat-resistant cultivars.

• Journal of Life Science
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• v.32 no.4
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• pp.310-317
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• 2022

Recently, interest in the harmful factors of particulate matter (PM), a major component of air pollution, has been increasing. In particular, PM_2.5 with a diameter of less than 2.5 ㎛ is well known to induce oxidative stress accompanied by autophagy in human lung epithelial cells. However, studies on whether PM_2.5 increases autophagy under oxidative stress and whether this process is reactive oxygen species (ROS)-dependent are insufficient. Therefore, in this study, we investigated whether PM_2.5 promotes autophagy through the generation of ROS in human alveolar epithelial A594 cells. According to our results, cells co-treated with PM_2.5 and hydrogen peroxide (H₂O₂) showed a lower cell viability than cells treated with each alone, which was associated with increased total and mitochondrial ROS production. The co-treatment of PM_2.5 and H₂O₂ also increased autophagy induction, which was confirmed through Cyto-ID staining, and the expression of autophagy biomarker proteins increased. However, when ROS generation was artificially blocked by N-acetyl-L-cysteine pretreatment, the reduction in cell viability and induction of autophagy by PM_2.5 and H₂O₂ co-treatment were markedly attenuated. Therefore, the present results suggest that PM_2.5-induced ROS generation may play a critical role in autophagy induction in A549 cells.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.421-433
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• 2023

The final disposal of spent nuclear fuel(SNF) from nuclear power plants takes place in a deep geological repository. The metal canister encasing the SNF is made of cast iron and copper, and is engineered to effectively isolate radioactive isotopes for a long period of time. The SNF is further shielded by a multi-barrier disposal system comprising both engineering and natural barriers. The deep disposal environment gradually changes to an anaerobic reducing environment. In this environment, sulfide is one of the most probable substances to induce corrosion of copper canister. Stress-corrosion cracking(SCC) triggered by sulfide can carry substantial implications for the integrity of the copper canister, potentially posing a significant threat to the long-term safety of the deep disposal repository. Sulfate can exist in various forms within the deep disposal environment or be introduced from the geosphere. Sulfate has the potential to be transformed into sulfide by sulfate-reducing bacteria(SRB), and this converted sulfide can contribute to the corrosion of the copper canister. Bentonite, which is considered as a potential material for buffering and backfilling, contains oxidized sulfate minerals such as gypsum(CaSO4). If there is sufficient space for microorganisms to thrive in the deep disposal environment and if electron donors such as organic carbon are adequately supplied, sulfate can be converted to sulfide through microbial activity. However, the majority of the sulfides generated in the deep disposal system or introduced from the geosphere will be intercepted by the buffer, with only a small amount reaching the metal canister. Pyrite, one of the potential sulfide minerals present in the deep disposal environment, can generate sulfates during the dissolution process, thereby contributing to the corrosion of the copper canister. However, the quantity of oxidation byproducts from pyrite is anticipated to be minimal due to its extremely low solubility. Moreover, the migration of these oxidized byproducts to the metal canister will be restricted by the low hydraulic conductivity of saturated bentonite. We have comprehensively analyzed and summarized key research cases related to the presence of sulfates, reduction processes, and the formation and behavior characteristics of sulfides and pyrite in the deep disposal environment. Our objective was to gain an understanding of the impact of sulfates and sulfides on the long-term safety of high-level radioactive waste disposal repository.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.79-88
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• 2008

Recently, the high speed railway comes into the spotlight as the important and convenient traffic infrastructure. In Korea, Kyung-Bu high speed train service began in bout 400 km section in 2004, and the Ho-Nam high speed railway will be constructed by 2017. The high speed train will run with a design maximum speed of 300-350 km/hr. Since the trains are operated at high speed, the differential settlement of subgrade under the rail is able to cause a fatal disaster. Therefore, the differential settlement of the embankment must be controlled with the greatest care. Furthermore, the characteristics and causes of settlements which occurred under construction and post-construction should be investigated. A considerable number of studies have been conducted on the settlement of the natural ground over the past several decades. But little attention has been given to the compression settlement of the embankment. The long-term settlement of compacted fills embankments is greatly influenced by the post-construction wetting. This is called 'hydro collapse' or 'wetting collapse'. In spite of little study for this wetting collapse problem, it has been recognized that the compressibility of compacted sands, gravels and rockfills exhibit low compressibility at low pressures, but there can be significant compression at high pressures due to grain crushing (Marachi et al. 1969, Nobari and Duncan 1972, Noorany et al. 1994, Houston et al. 1993, Wu 2004). The characteristics of compression of fill materials depend on a number of factors such as soil/rock type, as-compacted moisture, density, stress level and wetting condition. Because of the complexity of these factors, it is not easy to predict quantitatively the amount of compression without extensive tests. Therefore, in this research I carried out the wetting collapse tests, focusing on various soil/rock type, stress levels, wetting condition more closely.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.5
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• pp.651-663
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• 2016

Corn silk, Job's tears, Lentinus edodes, and apple peel 70% ethanol extracts (CS, JT, LE, and AP) were studied for their antioxidant activities. CS among all extracts showed the highest antioxidant activities based on total polyphenol and flavonoid contents, 2,2-diphenyl-${\beta}$-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical scavenging activity, and reducing power. Adipocyte differentiation was investigated by Oil Red O staining assay using CS, JT, LE, AP, and extract of developed bread containing corn silk, Job's tears, Lentinus edodes, and apple peel (DB) treated to 3T3-L1 adipocytes. DB1 and DB2 showed anti-adipogenic and antioxidant effects. Triglyceride (TG) accumulation in 3T3-L1 cells was measured, and among the samples tested (CS, JT, LE, and AP), CS was found to have the highest inhibitory activity against TG accumulation of differentiated 3T3-L1 adipocytes and regulated factors associated with adipogenesis. CS suppressed lipid droplet formation and adipocyte differentiation in 3T3-L1 cells in a dose-dependent manner. We examined the effects of CS on the levels of CCAAT-enhancer-binding protein ${\beta}(C/EBP{\beta})$, peroxisome proliferator activated receptor ${\gamma}(PPAR{\gamma})$, and adipocyte-specific lipid binding protein (aP2) mRNA as well as protein levels in 3T3-L1 cells treated with CS at various concentrations (0, 10, 50, and $100{\mu}g/mL$) during adipocyte differentiation and treatment with CS in 3T3-L1 adipocytes down-regulated expression of $PPAR{\gamma}$ and aP2 mRNA. CS also significantly inhibited up-regulation of $C/EBP{\beta}$, $PPAR{\gamma}$, and aP2 proteins during adipocyte differentiation. These data indicate that DBs have anti-adipogenic activity induced by CS in 3T3-L1 preadipocytes, and CS exerts anti-adipogenic activity by inhibiting expression of $C/EBP{\beta}$, $PPAR{\gamma}$, and aP2 signaling pathway in 3T3-L1 adipocytes. JT, LE, and AP had no inhibitory effects on differentiation of 3T3-L1 preadipocytes but displayed strong antioxidant effects. These results suggest that the developed bread may be a health beneficial food that can prevent or treat obesity and diseases induced by oxidative stress.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.3
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• pp.325-334
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• 2013

The objective of this study was to compare the content and metabolic activities between fresh pine needle juice (PNJ) and fermented pine needle juice (FPNJ). A variety of factors were measured, including total phenolic content (TPC), antioxidant activity [DPPH radical scavenging activity (RSA), total radical-trapping antioxidant potential (TRAP), oxygen radical absorbance capacity (ORAC), cellular antioxidant capacity (CAC)], anti-genotoxic activity, ${\alpha}$-glucosidase inhibitory activity, and angiotensin converting enzyme (ACE) inhibitory activity. The TPC was $17.3{\pm}0.2$ and $4.6{\pm}0.0$ mg GAE/g in PNJ and FPNJ, respectively. The DPPH RSA, TRAP, and ORAC values increased in a dose-dependent manner for both PNJ and FPNJ, with significantly higher activities in PNJ than FPNJ. The CAC against AAPH-induced oxidative stress in HepG2 cells was protected by both PNJ and FPNJ. Pretreatment with PNJ and FPNJ in human leukocytes produced significant reductions in $H_2O_2$-induced DNA damage at a concentration of $50{\mu}g/mL$. ${\alpha}$-Glucosidase inhibitory activity was significantly higher in FPNJ than PNJ. The ACE inhibitory activity was about 87.1% and 60.0% in 1:1 diluted PNJ and FPNJ, respectively. This study suggests that the fermentation of PNJ could enhance the regulation of blood glucose metabolism and both PNJ and FPNJ might be a new potential source of natural antioxidant, anti-diabetic, and anti-hypertensive agents applicable to food.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.252-261
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• 2003

Although the young spike of barley (Hordeum vulgare L.) or wheat (Triticum aestivum L.) is known as the most susceptible part to spring cold injury, the risk of cold injury is apt to be ignored in most breeding program due to the importance of early maturity. Based on these aspects, the types and inducing time, temperature conditions for induction and effects of cold injury on growth and yield in this study were investigated under greenhouse and field conditions through three years (1997-1999). In natural condition, low temperature around -2.4∼$-10.2^{\circ}C$ caused the death of plant. Several cold injury types such as partial degeneration of spike, partial discoloration of leaf, spike and awn, discoloration of culm and white spike were observed at low temperature around $-3.1^{\circ}C$. Low temperature around -2.4∼$-8.6^{\circ}C$ and 1.3-$7.6^{\circ}C$ caused degeneration and sterility of spike, respectively. Most materials were prepared to the spikelet foundation stage, spikelet differentiation stage, development stage of flower organ, booting stage and heading stage, which were known having risk for cold injury in field condition. Although most of the controlled stages were sensitive to the induced low temperature, booting stage was the most sensitive stage for cold injury. All of growth stages which were treated-heading stage, booting stage, development stage of flower organ, spikelet differentiation stage, spikelet foundation stage-were responded to low temperature treatment but the symptoms revealed were very specific according to the growth stages. Ears of plant in heading stage were discolored to white. Ears of plant in booting stage were degenerated in all or part of one. Plants in spikelet differentiation stage were sterile in all or part of one. When tried to detect the specific differences between normal and cold injured plants in appearance, spike length, distance between spike and flag leaf and the first internode length could be the critical points for occurrence of spike death caused by cold injury. In barley, the elongation of spike was stopped on 3.2cm after occurrence of spike degeneration, 4.7cm after occurrence of partial degeneration of spike, 5.0cm after occurrence of white spike. In wheat, it was stopped on 1.6cm after occurrence of stem death, 3.3cm after occurrence of spike degeneration, 8.3cm after occurrence of partial degeneration of spike, 8.1cm after occurrence of white spike, 7.5cm after partial discoloration of leaf and 9.3cm after partial discoloration of spike. The obtained results from low temperature treatment induced in growth chamber were similar to the field experiment, Beacuse the death of spikes was more when low temperature was treated two times than one times, the temperature should be upgrade to -3$^{\circ}C$ in order to get the same condition with field test.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.568-576
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• 2017

As interest in functionality and environmentally friendly cosmetics is growing in recent years, materials that use safe and effective plant extracts have been developed. Therefore, this study also attempted to check the possibility of the graviola extract, which is known to have various efficacy mainly as a health functional material as a functional cosmetic material. In order to find out the antioxidant activity of graviola, we measured total polyphenol, total flavonoid content and DPPH radical scavenging activity and measured the ROS activity inhibition effect and cytoprotective effect on oxidative stress by treating HDF with hydrogen peroxide cells at an appropriate concentration after checking cytotoxicity in HDF cells. Based on the results of this experiment, the graviola extract was found to contain as high as 26.6 mg(CA)/100g, 14.3 mg(Q)/100g of total polyphenol and flavonoid, which are the antioxidant indexes and to have the high radical scavenging activity. The cell survival rate of the HDF cells was measured, and as a result, no significant cytotoxicity was observed at all concentrations and the experiment was carried out at a concentration of $100{\mu}g/mL$ afterwards. Inhibition of ROS activity in HDF cells induced by hydrogen peroxide was measured and the concentration-dependent inhibition of ROS activity was found and the cell protection effect of graviola was measured after hydrogen peroxide was treated for 4, 24 and 48 hours. As a result, the cell protection effect as high as 89.92% was confirmed at a $25{\mu}g/mL$ concentration up to 24 hours. As these results show that the graviola extract has excellent antioxidant activity, almost no toxicity to HDF cells, an effective activity inhibitory effect on active oxygen generated by hydrogen peroxide and excellent cytoprotective effect, the possibility as various functional materials with antioxidant and cytoprotective effects was confirmed.