• Journal of the Mineralogical Society of Korea
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• v.26 no.2
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• pp.101-110
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• 2013

Due to the large specific surface area and great reactivity toward environmental contaminants, nanocrystalline mackinawite (FeS) has been widely applied for the remediation of contaminated groundwater and soil. Furthermore, nanocrystalline FeS is rather thermodynamically stable against anoxic corrosion, and its reactivity can be regenerated continuously by the activity of sulfate-reducing bacteria. However, nanocrystalline mackinawite is prone to either spread out along the groundwater flow or cause pore clogging in aquifers by particle aggregation. Accordingly, this mineral should be modified for the application of permeable reactive barriers (PRBs). In this study, coating methods were investigated by which mackinawite nanoparticles were deposited on the surface of alumina or activated alumina. The amount of FeS coating was found to significantly vary with pH, with the highest amount occurring at pH ~6.9 for both minerals. At this pH, the surfaces of mackinawite and alumina (or activated alumina) were oppositely charged, with the resultant electrostatic attraction making the coating highly effective. At this pH, the coating amounts by alumina and activated alumina were 0.038 and 0.114 $mmol{\cdot}FeS/g$, respectively. Under anoxic conditions, arsenite sorption experiments were conducted with uncoated alumina, uncoated activated alumina, and both minerals coated with FeS at the optimal pH for comparison of their reactivity. Uncoated activated alumina showed the higher arsenite removal compared to uncoated alumina. Notably, the arsenite sorption capacity of activated alumina was little changed by the coating with FeS. This might be attributed to the abundance of highly reactive hydroxyl functional groups (${\equiv}$AlOH) on the surface of activated alumina, making the arsenite sorption by the coated FeS unnoticeable. In contrast, the arsenite sorption capacity of alumina was found to increase substantially by the FeS coating. This was due to the consumption of the surface hydroxyl functional groups on the alumina surface and the subsequent occurrence of As(III) sorption by the coated FeS. Alumina, on the surface area basis, has about 8 times higher FeS coating amount and higher As(III) sorption capacity than silica. This study indicates that alumina is a better candidate than silica for the coating of nanocrystalline mackinawite.

• Journal of the Korean association of regional geographers
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• v.22 no.1
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• pp.151-167
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• 2016

Conventional social science typically regards the idea of a 'mountain' as part of 'nature' and a physical environment existing separately from, or prior to, human society and culture. However, in Korea, which is 70% mountainous land, the 'mountain' is part of a unique 'social nature'. This research develops the idea that in this context the mountain is a social nature and a cultural landscape which are tied heavily to the idea of travel. The article interrogates why the scenic beauties of Mt. Kumgang have been perceived and conveyed through multiple generations since the Chosun Dynasty period. Focusing on Mt. Kumgang, this article illustrates how strongly people have held dreams of mountain travel, for the whole life-time. Travel writings(or accounts of trips to the mountain) and artwork have played a particularly important role in creating Mt. Kumgang's reputation as the most beautiful mountain in the country. At the same time, the access to the mountain was often a dangerous adventure, with many travelers facing hunger and extreme physical challenges. As portrayed in writings and artwork, the overall effect of these dynamics was the creation of a socionatural place of striking beauty that even seemed to have mystical or magical fantasy. According to Confucian ideals, full appreciation of nature and its beauty was key to understanding the logics of the universe and to achieving a high moral standard, which contributed to decide to leave for the mountain as well. The essays, poems, and paintings of Mt. Kumgang since the Chosun Dynasty period that portrayed the mountain's beauty collectively served to produce the mountain as a socionatural landscape engendered with potent place-myths, important historical meaning, and strong aesthetic associations. Thus, the travel to the mountain seemed never completed over until travelers had completed various artistic representations to record and to memorize what they'd done and seen in Mt. Kumgang, which had been performed for the strong purpose of social sharing of the real the mountain's beauties and itinerary.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.2
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• pp.143-151
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• 2010

The impact of climate change on rice plants in Gangwon province was examined by comparing the climatic conditions during the recent 10 years (2000~2009) with those of normal (1971~2000) years, and by evaluating the rice plant responses. The daily mean air temperature increased by $0.5^{\circ}C$ while the daily range decreased by $0.1^{\circ}C$ as compared with the normal years. During the main rice growing period in field (from June to September) precipitation increased from 900 to 1,051mm and sunshine hours decreased from 704 to 619 hours. The respiration consumption effect during the rice growing period increased by 0.07 as a result of increased air temperature and reduced sunshine hours. The optimum heading date (determined by the mean air temperature for 40 days after the heading) was delayed in Chuncheon, Hongcheon, Wonju, and Gangneung compared with the normal. The maximum climatic yield potential based on mean temperature and sunshine hours for 40 days after the rice heading decreased by 94 kg/10a mainly due to the decrease in sunshine. The mean air temperature for 40 days after the rice heading from 1999 to 2009 in Chuncheon, Cheorwon, and Gangneung was generally above $22^{\circ}C$ implying that yield and quality of rice can be reduced. Therefore, it is necessary to delay the heading date by planting mid- to late-maturing varieties or by changing the transplanting date in order to produce high quality rice and to maintain rice productivity. In addition, it is also important to develop or select cultivars suitable to changing climate for each region in Gangwon province.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.501-510
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• 2006

To investigate the effects of MLSS concentration and influent C/N ratio on the nitrogen removal efficiency of alternately intermittently aerated nonwoven fabric filter bioreactors, the MLSS concentrations of the reactors were maintained at approximately 5,500 mg/L, 10,000 mg/L and 15,000 mg/L, and the influent TCOD/TKN ratio was decreased gradually from 5 to 2 by adding $NH_4Cl$. The influent was prepared by diluting a food waste leachate to a TCOD concentration of about 300 mg/L. The results of the experiment showed F/M ratios less than 0.112 g TCOD/g MLSS-day, average TCOD removal efficiencies of above 95%, and an average observed microbial yield coefficient of 0.283 g MLSS/g COD removed. The nitrification efficiencies were computed to be always better than 96% except one case where the nitrification efficiency was 90.5% when the MLSS concentration and the influent TCOD/TKN ratio was 5,500 mg/L and 2, respectively. The denitrification efficiency deteriorated as the influent TCOD/TKN ratio decreased. The average denitrification efficiency at the MLSS concentration of 10,000 mg/L was 10.7% better than that at the MLSS concentration of 5,500 mg/L, and the denitrification rate improved at a rate of 2.66 mg NL as the MLSS concentration increased by 1,000 mg/L. When the MLSS concentration was 15,000 mg/L, however, the average denitrification efficiency was merely 4.6% higher compared to when the MLSS concentration was 5,500 mg/L, and the denitrification rate increased at a rate of 0.75 mg N/L per 1,000 mg/L MLSS increase. Therefore, no strict proportional relationship was found between MLSS concentration and endogenous denitrification rate. The average alkalinity consumption rate was 3.36 mg alkalinity/mg T-N removed, which is similar to the theoretical value of 3.57 mg alkalinity/mg T-N removed, but the rate increased as the influent TCOD/TKN ratio decreased.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.7
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• pp.473-479
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• 2012

Water reuse has been highlighted as a representative alternative to solve the lacking water resource. This study carried out a study on the pipe corrosion and water quality change which can occur through the supply of reclaimed water, using a simulated reclaimed water distribution pipeline. Galvanized steel pipe (GSP), cast iron pipe (CIP), stainless steel pipe (STSP) and PVC pipe (PVCP) were used for the pipe materials. Reclaimed water(RW) and tap water(TW) were respectively supplied into simulated reclaimed water distribution pipelines. As a result of performing a loop test to supply reclaimed water to simulated reclaimed water distribution pipelines, the weight reduction of pipe coupons showed the sequence of CIP > GSP > STSP ${\approx}$ PVCP. In addition, reclaimed water showed a high corrosion rate comparing to that of tap water. In case of CIP, the initial corrosion rate showed 3.511 mdd(milligrams per square decimeter per day) for reclaimed water and 2.064 mdd for tap water and the corrosion rate for 90 days showed 0.833 mdd for reclaimed water and 0.294 mdd for tap water. Also in case of GSP, the initial corrosion rate showed 2.703 mdd for reclaimed water and 2.499 mdd for tap water and the corrosion rate for 90 days showed 0.349 mdd for reclaimed water and 0.248 mdd for tap water, which was a tendency similar to that appeared in CIP with a tendency to reduce the corrosion rate. As a result of water quality changes of reclaimed water at pipe materials to carry out the loop test, there was higher conversion ratio of ammonia into nitrate in CIP and GSP with higher corrosion rate than that in STSP and PVCP where no corrosion has occurred. The highest denitrification rate of nitrate could be observed from CIP with the most particles generated from corrosion. In CIP, it could be confirmed that there was MIC (Microbiologically Induced Corrosion) as a result of EDS (Energy Dispersive X-ray spectrometer System) analysis results.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.1
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• pp.60-68
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• 2015

The study of waste activated sludge (WAS) solubilization has been increased for sludge volume reduction and enhancing the efficiency of anaerobic digestion. Microwave (MW)-assisted solubilization is an effective method for the solubilization of WAS because this method can lead to thermal, nonthermal effect and ionic conduction by dielectric heating. In this study, the solubilization of WAS by MW heating and conductive heating (CH) was compared and to enhance the MW-assisted solubilization of WAS at low MW output power, chemical agents were applied such as $H_2SO_4$ as the strong acid and $CaCl_2$, NaCl as the ionic materials. Compared to the COD solubilization of WAS by CH, that by MW heating was approximately 1.4, 6.2 times higher at $50^{\circ}C$, $100^{\circ}C$, respectively and the highest COD solubilization of WAS was 10.0% in this study of low MW output power condition. At the same MW output power and reaction time in chemically agents assisted experiments, the COD solubilization of WAS were increased up to 18.1% and 12.7% with the addition of $H_2SO_4$ and NaCl, however, that with the addition of $CaCl_2$ was 10.7%. This result might be due to the fact that the precipitation reaction occurred by calcium ion ($Ca^{2+}$) and phosphate ion (${PO_4}^{3-}$) produced in WAS after MW-assisted solubilization. In this study, $H_2SO_4$ turned out to be the optimal agent for the enhancement of MW efficiency, the addition of 0.2 M $H_2SO_4$ was the most effective condition for MW-assisted WAS solubilization.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.8
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• pp.1202-1209
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• 2005

The purpose of this study was to observe the effects of high-carbohydrate (HC) diet, high-protein (HP) diet and high-fat (HF) diet with a normal diet (N) on diet-induced thermogenesis (DIT) in healthy Korean women. The four isoenergetic test meals consisted as follows: HC (75$ \% $ energy from carbohydrate, 10$ \% $ from protein and 15$ \% $ from fat), HP (10$ \% $ energy from carbohydrate, 75$ \% $ from protein and 15$ \% $ from fat) HF (15$ \% $ energy from carbohydrate, 10$ \% $ from protein and 75$ \% $ from fat) diet and N (65$ \% $ energy from carbohydrate, 15$ \% $ from protein and 20$ \% $ from fat) diet. Fasting and postprandial thermogenesis were measured after each test meals in eight subjects by indirect calorimetry for 3 hours. Fasting and postprandial serum glucose, insulin and triacylglycerol contents were also measured for 3 hours. DIT were 10.4$\pm$3.2 for HC, 12.7$\pm$0.5 for HP, 6.9$\pm$2.8 for HF and 8.7$\pm$4.8 for N diet as a percentage of the energy load. DIT of HP was greater than HF significantly, but had no differences with HC and N Integrated areas under the curves ($ \delta- $-AUC) of plasma glucose and insulin were significantly higher for HC compared to HP, HF and N diets. $ \delta$-AUC of plasma triacylglycerol was significantly higher for HF compared to the other test meals. In conclusion, intake of protein rich meal stimulates postprandial energy expenditure, but has no relation between DIT and insulin response, body composition.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.9
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• pp.1208-1214
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• 2011

Caffeine, a psychoactive stimulant, has been implicated in the modulation of learning and memory functions due to its action as a non-selective adenosine receptors antagonist. On the contrary, some side effects of caffeine have been reported, such as an increased energy loss and metabolic rate, decrease DNA synthesis in the spleen, and increased oxidative damage to exerted on LDL particles. Therefore, the aim of this study was to develop a safe stimulant from natural plants mixture (Aralia elata, Acori graminei Rhizoma, Chrysanthemum, Dandleion, Guarana, Shepherd's purse) that can be used as a substitute for caffeine. Thirty SD rats were divided into three groups; control group, caffeine group (15.0 mg/kg, i.p.), and natural plants mixture group (NP, 1 mL/kg, p.o.). The effect of NP extract on stimulant activity was evaluated with open-field test (OFT) and plus maze test for measurement of behavioral profiles. Plasma lipid profiles, lipid peroxidation in LDL (conjugated dienes), total antioxidant capacity (TRAP) and DNA damage in white blood, liver, and brain cells were measured. In the OFT, immobility time was increased significantly by acute (once) and chronic (3 weeks) supplementation of NP and showed a similar effect to caffeine treatment. Three weeks of caffeine treatment caused plasma lipid peroxidation and DNA damage in liver cells, whereas there were no changes in the NP group. NP group showed a higher plasma HDL cholesterol concentration compared to the caffeine group. The results indicate that the natural plants mixture had a stimulant effect without inducing oxidative stress.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.4
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• pp.459-464
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• 2017

Biphenyl is used as an intermediate in the production of crop protection products, a solvent in pharmaceutical production, and as a component in the preservation of citrus fruits in many countries. Biphenyl is not authorized for use and also does not have standards or specifications as a food additive in Korea. National and imported food products are likely to contain biphenyl. Therefore, control and management of these products is required. In this study, a simple analytical method was developed and validated using HPLC to determine biphenyl in food. These methods are validated by assessing certain performance parameters: linearity, accuracy, precision, recovery, limit of detection (LOD), and limit of quantitation (LOQ). The calibration curve was obtained from 1.0 to $100.0{\mu}g/mL$ with satisfactory relative standard deviations (RSD) of 0.999 in the representative sample (orange). In the measurement of quality control (QC) samples, accuracy was in the range of 95.8~104.0% within normal values. The inter-day and inter-day precision values were less than 2.4% RSD in the measurement of QC samples. Recoveries of biphenyl from spiked orange samples ranged from 92.7 to 99.4% with RSD between 0.7 and 1.7% at levels of 10, 50, and $100{\mu}g/mL$. The LOD and LOQ were determined to be 0.04 and $0.13{\mu}g/mL$, respectively. These results show that the developed method is appropriate for biphenyl identification and can be used to examine the safety of citrus fruits and surface treatments containing biphenyl residues.

• Tuberculosis and Respiratory Diseases
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• v.43 no.6
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• pp.976-986
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• 1996

BACKGROUND : Dyspnea is common among patients with cardiopulmonary disease, and "daily disability" is defined as a functional impairment resulting from exercise intolerance. The maximal oxygen uptake(VO2max) during exhausting work is not only the best single physical indicator of the capacity of a man for sustaining hard muscular work, but also the most objective method by which one can determine the physical fitness of an individual as reflected by his cardiovascular system. However, the expense, time and personnel requirements make this procedure prohibitive for testing large group. The walking test is well-known type of exercise and it cost nothing to perform and have good reproducibility. Thus we performed the walking test and investigated correlations with spirometry, ABG and exercise test. METHOD: We observed the walking test and exercise test by cycle ergometer in 37 patients who visited our hospital because of dyspnea. Arterial blood gas analysis and spiromety, dyspnea index were performed, too. RESULT : (1) The VO2max was significantly lower in patients with COPD and cardiovascular disease than asthma and dyspnea on exertion group(p<0.05). The walking test distance was also lower in former. (2) The 12 minute walking test was significantly correlated with VO2max, PaCO2, FVC(%), FEV1(%) in all patients(p<0.05), and the walking test was only conelated with VO2max in patients with COPD(p<0.05). (3) In COPD patients, the VO2max was best correlated with FEV1(%) and FVC(%) and significantly correlated with walking test. But there was no correlation between walking test and FEV1(%) & FVC(%). (4) The 6 minute walking test was well correlated with 12 minute walking test(r=0.92. p<0.01). CONCLUSION : The walking test is the simple method for assessing exercise performance in patient with cardiopulmonary disease and a reliable indicator for VO2max. And the walking test is practical method for assessing on everyday disability rather than maximal exercise capacity. The 6 minute walking test is highly correlated with 12 minute walking test and a less exhausting for the patients and a time-saving for the investigator.