• Korean Journal of Food Science and Technology
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• v.47 no.3
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• pp.380-387
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• 2015

The anti-amnesic effect of Artemisia argyi H against trimethyltin (TMT)-induced learning and memory impairment and its neuroprotective effect against $H_2O_2$-inducedoxidative stress were investigated. Cognitive behavior was examined by Y-maze and passive avoidance test for 4 weeks, which showed improved cognitive functions in mice treated with the extract. In vitro neuroprotective effects against $H_2O_2$-induced oxidative stress were examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium-bromide and lactate dehydrogenase (LDH) assays. A. argyi H. extract showed protective effects against $H_2O_2$-induced neurotoxicity; moreover, LDH release into the medium was inhibited. Finally, high-performance liquid chromatography (HPLC) analysis showed that eupatilin and jaceosidin were the major phenolic compounds in A. argyi H. extract. These results suggest that A. argyi H. could be a good source of functional substances to prevent neurodegenerative diseases.

• Tuberculosis and Respiratory Diseases
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• v.46 no.6
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• pp.846-855
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• 1999

Background : Secondary pulmonary hypertension is an important final endpoint in patients with chronic hypoxic lung disease, accompanied by deterioration of pulmonary hemodynamics. The clinical diagnosis of pulmonary hypertension and/or cor pulmonale could be difficult, and simple noninvasive evaluation of pulmonary artery pressures has been an relevant clinical challenge for many years. Doppler echocardiography might to be a more reliable method for evaluating pulmonary hemodynamics in such patients in terms of the accuracy, reproducibility and easiness for obtaining an appropriate echocardiographic window than M-mode echocardiography. The aim of this study was to assess echocardiographic parameters associated with pulmonary arterial hypertension, defined by increasing right ventricular systolic pressure(RVSP), calculated from trans-tricuspid gradient in patients with chronic hypoxic lungs. Method : We examined 19 patients with chronic hypoxic lung disease, suspected pulmonary hypertension under the clinical guidelines by two dimensional echocardiography via the left parasternal and subcostal approach in a supine position. Doppler echocardiography measured RVSP from tricuspid regurgitant velocity in continuous wave with 2.5MHz transducer and acceleration time(AT) on right ventricular outflow tract in pulsed wave for the estimation of pulmonary arterial pressure. Results : On echocardiography, moderate to severe degree of pulmonary arterial hypertension was defined as RVSP more than 40mmHg, presenting tricuspid regurgitation. Increased right ventricular endsystolic diameter and shortened AT were noted in the increased RVSP group. Increased RVSP was correlated negatively with the shortening of AT. Other clinical data, including pulmonary functional parameters, arterial blood gas analysis and M mode echocardiographic parameters were not changed significantly with the increased RVSP. Conclusion : These findings suggest that shortened AT on pulsed doppler can be useful when quantifying pulmonary arterial pressure with increased RVSP in patients with chronic lung disease with hypoxemia. Doppler echocardiography in pulmonary hypertension of chronic hypoxic lungs is an useful option, based on noninvasiveness under routine clinical practice.

• Economic and Environmental Geology
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• v.44 no.3
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• pp.217-228
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• 2011

The feasibility study for the stabilization process using 5 amendments was performed to quantify As-immobilization efficiency in farmland soils around Samkwang abandoned mine, Korea. For the batch experiments, with 2% and 3% of granular lime(2-5 mm in diameter), leaching concentration of As from the soil decreased by 86% and 95% respectively, compared to that without the amendment. When 5% and 10% of granular limestone was added in the soil, As concentration decreased by 82% and 95%, showing that lime and limestone has a great capability to immobilize As in the soil. From the results of batch experiments, continuous column(15 cm in dimeter and 100 cm in length) tests using granular lime and limestone as amendments was performed. Without the amendment, As concentration from the effluent of the column ranged from 167 ${\mu}g$/L to 845 ${\mu}g$/L, which were higher than Korea Drinking Water Limit(50 ${\mu}g$/L). However, only with 1% and 2% of lime, As concentration from the column dramatically decreased by 97% for 9 years rainfall and maintained below 50 ${\mu}g$/L. With 5% of limestone and the mixed amendment(1% of lime + 2% of limestone), more than 95% diminution of As leaching from the column occurred within I year rainfall and maintained below 20 ${\mu}g$/L, suggesting that the capability of limestone to immobilize As in the farmland soil was outstanding and similar to that of lime. Results of experiments suggested that As stabilization process using limestone could be more available to immobilize As from the soil than using lime because of low pH increase and thus less harmful side effect.

• Journal of Climate Change Research
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• v.2 no.4
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• pp.237-251
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• 2011

This study presents a review on the recent climate change over the Korean peninsula, which has experienced a significant change due to the human-induced global warming more strongly than other regions. The recent measurement of carbon dioxide concentrations over the Korean peninsula shows a faster rise than the global average, and the increasing trend in surface temperature over this region is much larger than the global mean trend. Recent observational studies reporting the weakened cold extremes and intensified warm extremes over the region support consistently the increase of mean temperature. Surface vegetation greenness in spring has also progressed relatively more quickly. Summer precipitation over the Korean peninsula has increased by about 15% since 1990 compared to the previous period. This was mainly due to an increase in August. On the other hand, a slight decrease in the precipitation (about 5%) during Changma period (rainy season of the East Asian summer monsoon), was observed. The heavy rainfall amounts exhibit an increasing trend particularly since the late 1970s, and a consecutive dry-day has also increased primarily over the southern area. This indicates that the duration of precipitation events has shortened, while their intensity became stronger. During the past decades, there have been more stronger typhoons affecting the Korean peninsula with landing more preferentially over the southeastern area. Meanwhile, the urbanization effect is likely to contribute to the rapid warming, explaining about 28% of total temperature increase during the past 55 years. The impact of El Nino on seasonal climate over the Korean peninsula has been well established - winter [summer] temperatures was generally higher [lower] than normal, and summer rainfall tends to increase during El-Nino years. It is suggested that more frequent occurrence of the 'central-Pacific El-Nino' during recent decades may have induced warmer summer and fall over the Korean peninsula. In short, detection and attribution studies provided fundamental information that needed to construct more reliable projections of future climate changes, and therefore more comprehensive researches are required for better understanding of past climate variations.

• Geophysics and Geophysical Exploration
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• v.26 no.2
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• pp.52-61
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• 2023

The use of ultra-high-resolution (UHR) seismic surveys to preceisly characterize coastal and shallow structures have increased recently. UHR surveys derive a spatial resolution of 3.125 m using a high-frequency source (80 Hz to 1 kHz). A digital streamer system is an essential module for acquiring high-quality UHR seismic data. Localization studies have focused on reducing purchase costs and decreasing maintenance periods. Basic performance verification and application tests of the developed streamer have been successfully carried out; however, a comparative analysis with the existing benchmark model was not conducted. In this study, we characterized data obtained by using a developed streamer and a benchmark model simultaneously. Tamhae 2 and auxiliary equipment of the Korea Institute of Geoscience and Mineral Resources were used to acquire 2D seismic data, which were analyzed from different perspectives. The data obtained using the developed streamer differed in sensitivity from that obtained using benchmark model by frequency band.However, both type of data had a very high level of similarity in the range corresponding to the central frequency band of the seismic source. However, in the low frequency band below 60 Hz, data obtained using the developed streamer showed a lower signal-to-noise ratio than that obtained using the benchmark model.This lower ratio can hinder the quality in data acquisition using low-frequency sound sources such as cluster air guns. Three causes for this difference were, and streamers developed in future will attempt to reflect on these improvements.