• Journal of Energy Engineering
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• v.21 no.4
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• pp.346-355
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• 2012

Recent in the world environmental issues and energy depletion problems have been received attention. One way to solve these problems is to use hybrid electric vehicles (HEVs). Therefore, the interest in HEV technology is higher than ever before. Viable candidates for the energy-storage systems in HEV applications may be absorbent glass mat (AGM) lead-acid, nickel-metal-hydride (Ni-MH) and rechargeable lithium batteries. The AGM battery has advantages in terms of relatively low cost, high charge efficiency, low self-discharge, low maintenance requirements and safety as compared to the other batteries. In order to implement HEV system in required more electric power commercial vehicles AGM batteries was connected to 2 series-2 parallels (2S2P). In this study, a one-dimensional modeling is carried-out to predict the behaviors of 2S2P AGM batteries system during charge and discharge. The model accounts for electrochemical reaction rates, charge conservation and mass transport. In order to validate the model, modeling results are compared with the experimentally measured data in various conditions.

• Journal of Microbiology and Biotechnology
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• v.18 no.8
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• pp.1459-1469
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• 2008

Using a rotating biological contactor modified with a sequencing bath reactor system (SBRBC) designed and operated to remove phosphate and nitrogen [58], the microbial community structure of the biofilm from the SBRBC system was characterized based on the extracellular polymeric substance (EPS) constituents, electron microscopy, and molecular techniques. Protein and carbohydrate were identified as the major EPS constituents at three different biofilm thicknesses, where the amount of EPS and bacterial cell number were highest in the initial thickness of 0-100${\mu}m$. However, the percent of carbohydrate in the total amount of EPS decreased by about 11.23%, whereas the percent of protein increased by about 11.15% as the biofilm grew. Thus, an abundant quantity of EPS and cell mass, as well as a specific quality of EPS were apparently needed to attach to the substratum in the first step of the biofilm growth. A FISH analysis revealed that the dominant phylogenetic group was $\beta$- and $\gamma$-Proteobacteria, where a significant subclass of Proteobacteria for removing phosphate and/or nitrate was found within a biofilm thickness of 0-250${\mu}m$. In addition, 16S rDNA clone libraries revealed that Klebsiella sp. and Citrobacter sp. were most dominant within the initial biofilm thickness of 0-250${\mu}m$, whereas sulfur-oxidizing bacteria, such as Beggiatoa sp. and Thiothrix sp., were detected in a biofilm thickness over 250${\mu}m$. The results of the bacterial community structure analysis using molecular techniques agreed with the results of the morphological structure based on scanning electron microscopy. Therefore, the overall results indicated that coliform bacteria participated in the nitrate and phosphorus removal when using the SBRBC system. Moreover, the structure of the biofilm was also found to be related to the EPS constituents, as well as the nitrogen and phosphate removal efficiency. Consequently, since this is the first identification of the bacterial community and structure of the biofilm from an RBC simultaneously removing nitrogen and phosphate from domestic wastewater, and it is hoped that the present results may provide a foundation for understanding nitrate and phosphate removal by an RBC system.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1146-1153
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• 2008

Numerical simulation was carried out to study the trichloroethylene (TCE) degradation by permeable reactive barrier (PRB), and revealed the effect of concentration of TCE, iron medium mass, and concentration of iron-reducing bacteria (IRB). Newly developed model was based on axial dispersion reactor model with chemical and biological reaction terms and was implemented using MATLAB ver R2006A for the numerical solutions of dispersion, convection, and reactions over column length and elapsed time. The reaction terms include reactions of TCE degradation by zero-valent iron (ZVI, Fe$^0$) and ferrous iron (Fe$^{2+}$). TCE concentration in the column inlet was maintained as 10 mg/L. Equation for Fe$^0$ degradation includes only TCE reaction term, while one for Fe$^{2+}$ has chemical and biological reaction terms with TCE and IRB, respectively. Two coupled equations eventually modeled the change of TCE concentration in a column. At Fe$^0$ column, TCE degradation rate was found to be more than 99% from 60 hours to 235 hours, and declined to less than 1% in 1,365 hours. At the Fe$^{2+}$ and IRB mixed column, TCE degradation rate was equilibrated at 85.3% after 210 hours and kept it constant. These results imply that the ferrous iron produced by IRB has lowered the TCE degradation efficiency than ZVI but it can have higher longevity.http://kci.go.kr/kciportal/ci/contents/ciConnReprerSearchPopup.kci#

• Analytical Science and Technology
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• v.29 no.2
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• pp.65-72
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• 2016

This study presented an analytical method for detecting radium in soils using a liquid scintillation counter (LSC). The isotope ²²⁶Ra was extracted from soil using the fusion method and then separated from interfering radionuclides using the precipitation method. Radium was coprecipitated as sulfate salts with barium (Ba) and then converted into Ba(Ra)CO₃, which is soluble in an acidic solution. The isotope ²²²Rn, the decay progeny of ²²⁶Ra, was trapped in a water immiscible cocktail and analyzed by LSC. The pulse shape analysis (PSA) level was estimated using ⁹⁰Sr and ²²⁶Ra standard solutions. The figure of merit was the highest at PSA 80, while the alpha spillover was the lowest at PSA 80. The counting efficiency was 243 ± 2% in a glass vial. This analytical method was verified with International Atomic Energy Agency (IAEA) reference materials, including IAEA-312, IAEA-314, and IAEA-315. The recovery ranged from 60–82%, while the relative bias between the measured value and the recommended value was less than 10%. The minimum detectable activity was 2.1 Bq kg⁻¹ with dry mass 1 g, the background count rate of 0.02 cpm, the recovery rate of 70% and counting time of 30 min.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.4
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• pp.331-339
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• 2010

Shrimp farming is the most important mariculture industry on the west coast of South Korea. However, it has suffered from mass mortality due to viral disease outbreaks and coastal pollution due to water discharge. This study developed an intensive shrimp culture method for outdoor ponds, without water exchange, which minimizes the chance of viral transmission from the environment, reduces coastal pollution by water discharge and enhances shrimp production. A culture trial was conducted in two high-density polyethylene (HDPE)-lined ponds with a $550\;m^2$ surface area. The ponds were stocked with postlarvae of Litopenaeus vannamei, the major farmed shrimp species in Korea, on July 10, 2007, and cultured for 90 days with no water exchange. The stocking density of the postlarvae (B.W. 0.0015 g) was $272\;ind./m^2$, which is eight times higher than in traditional pond culture in Korea. At harvest, the total production of ponds 1 and 2 was 1,362kg ($2.48\;kg/m^2$) and 1,282 kg ($2.33\;kg/m^2$), respectively. This is 20~22 times higher than the mean farmed shrimp production ($0.112\;kg/m^2$) in Korea and about eight times higher than in traditional ponds with a good harvest. Although there was no water exchange throughout the culture period, the mean concentrations of unionized ammonia and nitrite-nitrogen were as low as 0.038 and 6.0 mg/L, respectively. The feed conversion rate (FCR) was 1.38, which is 20~45% lower than that of traditional pond cultures. The high efficiency of the diet in this study is thought to be due to a well-managed feeding strategy and well-developed bioflocs used as diet additions for the shrimp. The final body weight of the shrimp at harvest was low (12.2~12.5 g), compared with that of traditional pond culture. This may have resulted from the combination of a short culture period, high density of shrimp, and low temperature. This study suggests that a super-intensive shrimp pond culture method using biofloc technology with no water exchange can minimize viral transmission via water exchange, reduce coastal pollution, and enhance shrimp production.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.2
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• pp.313-322
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• 2020

Objective: An experiment was conducted to investigate the response of laying hens fed corn distiller's dried grains with solubles (DDGS) that are naturally contaminated with deoxynivalenol (DON). Methods: One hundred and sixty 52-week-old Lohmann Brown Lite hens were randomly allotted to five dietary treatments with 8 replicates per treatment. The dietary treatments were formulated to provide a range of corn DDGS contaminated with DON from 0% to 20% (i.e., 5% scale of increment). All laying hens were subjected to the same management practices in a controlled environment. Body weight, feed intake and egg production were measured biweekly for the entire 8-week experiment. The egg quality was measured biweekly for 8 weeks. On weeks 4 and 8, visceral organ weights, blood metabolites, intestinal morphology, and blood cytokine concentrations were measured. Results: The inclusion of corn DDGS contaminated with DON in the diet did not alter (p>0.05) the body weight, feed intake, hen-day egg production, egg mass and feed efficiency of the laying hens. No difference was found (p>0.05) in the egg quality of hens that were fed the dietary treatments. Furthermore, hens that were fed a diet containing corn DDGS contaminated with DON showed no change (p>0.05) in the visceral organ weights, the blood metabolites, and the cytokine concentrations. The crypt depth increased (p<0.05) as the amount of corn DDGS contaminated with DON increased. Proportionately, the villus height to crypt depth ratio of the laying hens decreased (p<0.05) with the increasing level of corn DDGS contaminated with DON in the diet. Conclusion: The inclusion of corn DDGS contaminated with DON up to 20% in layer diets did not cause changes in egg production performance and egg quality, which indicates that DON is less toxic at the concentration of 1.00 mg DON/kg.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.405-415
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• 2000

Experiments for autotrophic denitrification were performed using an upf10w reac1.or packed with sulfur particles as an electron donor. The influent $NO_3{^-}$-N concentration was kept almost constant, but the hydraulic retention time(HRT) and temperature varied. Results of the research showed that the denitrification efficiency and gas generation rate decreased as the HRT and temperature were reduced. During the HRT effect experiment, alkalinities of 3.44~5.71g, with an average of 4.67 g which is close to the theoretical value of 4.57g were consumed for each gram of $NO_3{^-}$-N removed. During the temperature effect experiment, however, the values were 6.58~13.41 g with an average of 9.12 g which is almost twice the theoretical value Denitrification along the length of the reactor appeared to be a first-order reaction with a reaction rate constant of 0.1648/hr. On the other hand, the sulfate generation showed a zero-order reaction with a reaction rate constant of 241/hr. There was some discrepancy in the nitrogen mass balance between the theoretical and measured values, requiring further researches.

• Journal of the Korean Professional Engineers Association
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• v.12 no.1
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• pp.12-20
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• 1979

The early history of gun powder (black powder) and explosives was closely connected with the discovery of methods of preparing and purifing salpetre (potassium nitrate KNO$_3$). The Chineses apparently became acquainted with salpetre firstly on about 11th century, and they were possibly the original discoverers of salpetre for raw material of gun powder. The Egyptians called it “Chinese snow”, and it is significant that Chingis-Khan, the Mongol conqueror, took the Chinese eenginees with him in 1218 to use it for attacking the fortifications of the Persian cities. The black powder was invented by chance by Chinese alchemists during the Song dynasty (11th century) in the process of manufacturing medicine, and the powder was introduced to Europe by Mongol army. The manufacturing method of salpetre and gun powder was introduced to Korea from China in 1374, and the powder alld gunnery manufacturing project was developed by Mu Sun Choe(崔茂宣), the first Korean engineer late in Koryo dynasty. Coming in to Yi dynasty the explosive technic, extractive method of salpetre, and gunnery manufacturing process were developed greatly by Mu Sun Choe and Hai Sin Choe (崔海臣). However, confronting with the Japanes invasion at Imjin War (1597) with more powerful western style rifles which had been introduced from the Portuguese, on the contrary Korean army with the traditional guns couldn't compete with them. The Chochong(烏銃, the western rifle introduced in Japane) were much superior to the Chinese style traditional guns in the shooting power and striking efficiency. On the other hand, the Japanese battle ships armed only with the Chochong, when confronted with the Korean turtle shaped ships under the commanding of Admiral Yi Sun-Sin(李舞臣), were defeated by the Korean canons on the ships. The technical development of the modern powder industry in Korea. with the construction of four big explosive plants from 1930 to 1945, has resulted the mass-production of explosives. This study was purposed to investigate to the process with regard to the details of introduction to the explosive technology in Korea, and intended to give a help to the engineers who are engaged in study of the explosive technics by means of giving a spot light data on the early process of the designs, and making suggestion to the researchers for further study and invent a new and modern explosive.

• Journal of Nutrition and Health
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• v.34 no.2
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• pp.123-131
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• 2001

The purpose of this study was to investigate the effects of diet composition on serum leptin and lipids profiles in rats. At the baseline, seven 4-week-old Sprague-Dawley rats, male, were sacrificed and the remaining rats were divided into five groups and each group was fed one of the following five dietary regiments for 2 weeks and 6 weeks;the control diet AIN76(CAL, n=2l), high-carbonhydrate(rice)(HCR, n=2l), high-carbohydrate(flour)(HCF, n=2l), high-fat(corn oil)(HFO, n=2l), high-fat(beef tallow)(HFB, n=2l). Serum leptin was determined by a double antibody ELISA assay at the baseline(n=7), 6 week(n=35) and 10 week of age(n=70). At 6 weeks of age, the increase in the Food Efficiency Ratio(FER) was related to adipocyte hyperplasia in rats on HFB diets. The serum triglyceride, total cholesterol, and LDL-cholesterol increased significantly in HFB group, and decreased in HFO group compared to control group. The HFC group showed significant increase in serum triglyceride level compared with control group. After 2 weeks and 6 weeks, noticeably high increases in epididymal adipose tissue fat cell mass and numbers were observed with the HFB fed group. Serum leptin levels increased as body weight increased over the period of time(4weeks; 1.50$\pm$0.13ng/ml versus 10weeks; 2.08$\pm$-.13ng/ml). And this result shows that there are 193% higher in rats fed high fat-beef tallow diet than the control diet. Serum leptin levels of the HFB group(4.01$\pm$0.39mg/ml) were significantly higher than that of the HFO(2.06$\pm$0.5613ng/ml), CAL(2.08$\pm$0.1313ng/ml), HCR(2.41$\pm$0.2113ng/ml) and HCF(2.80$\pm$0.4713ng/ml) at p<0.05. The serum leptin concentration was positively correlated with the amount of epididymal fat pads(r=0.47 p<0.01), serum triglyceride(r=0.49, p<0.001), tatal cholesterol(r=0.48, p<0.001), LDL-cholesterol(r=0.58, p<0.001), atherogenic index(r=0.67, p<0.001), and inversely correlated with HDL-cholesterol(r=-0.65, p<0.001). In conclusion, the changes in composition of dietary fat and carbohydrate intake could affect changes in concentration of serum lipids and leptin. Especially, the high-fat diet with animal fat source could increase circulating leptin level. (Korean J Nutrition 34(2) : 123-131, 2001)

• Journal of Distribution Science
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• v.15 no.5
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• pp.53-64
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• 2017

Purpose - This study focuses on use intention of mobile travel Apps by Chinese tourists visiting Korea based on UTAUT model, ISS model and ITM model. And the corresponding market promotion schemes are proposed for operators of mobile travel Apps by the research results. Research design, data, and methodology - After collecting 326 respondents in China with cross-sectional questionnaires, this study begins the empirical research with users of mobile travel Apps, and analyzes data with IBM SPSS 23.0 and IBM AMOS 23.0. Results - The results of this study include the following aspects: firstly, the System quality and Information quality are accepted for hypotheses of Satisfaction and Performance expectancy. Secondly, the Personal Propensity to Trust and Firm Reputation are accepted for Initial Trust hypothesis, and the hypotheses of Firm Reputation and Initial Trust are accepted for Use Intention. Thirdly, the Performance expectancy, Effort expectancy, Social influence are accepted for Use Intention hypothesis. Conclusions - With the increase of tourists visiting Korea, it can be predicted that the needs visiting Korea will be increased persistently for Chinese - this trend brings about the increase of the Chinese travel. First, information quality greatly influences satisfaction and performance expectancy. The research result shows that, the higher the mobile traveling App's information quality is, the higher the satisfaction and performance expectancy will be. Therefore, operators of mobile traveling App should have in-depth investigations towards users, to know the latter's real demand to the information quality and then provide corresponding services. Second, performance expectancy and effort expectancy greatly influence users' intention. Therefore, mobile traveling App operators should improve Apps' convenience and efficiency and, in doing so, find an effective method for market expansion. Third, social influence greatly affects users' intention. The result shows that mobile traveling App operators should pay attention to the influence of mass media and friends' recommendation on users, thereby it is necessary to improve advertisement activities. Fourth, initial trust also influences users' intention. The result shows that initial trust is a key element inducing users to generate use intention. Therefore, mobile traveling Apps operators should make efforts to catch elements that influence users' initial trust.