• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.25-30
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• 2011

Biogas obtained from the biodegradable organic wastes in an anaerobic digester consists of $CH_4$ and inert gases such as $CO_2$ and $N_2$. Since the composition of biogas varies by anaerobic digester conditions and the origin of wastes, it is necessary to respond to these variations so as to make stable combustion and accomplish high efficiency when it is used as a fuel for power generating SI engines. In this study, efforts have been made to investigate the effect of changes in the calorific values of biogas on the engine performance and exhaust characteristics. The biogas was simulated by supplying of $CH_4$ with $N_2$ dilution of various ratios, and ECM was developed to achieve accurate control of ignition and combustion. The results show that as the $CH_4$ concentration of the biogas decreases, the optimal spark timing is advanced due to the elevated thermal capacity and lowered $O_2$ concentration of the in-cylinder charge. Furthermore, since combustion temperature was reduced by increased inert gas, $NO_x$ emissions decreased, whereas THC emissions increased.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.783-792
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• 2007

To investigate the effects of alkalinity on the nitrification capability of the nonwoven fabric filter bioreactor(NFBR), an experiment was performed for 641 days at a hydraulic retention time of approximately 11 hours by changing the influent concentration of $NH_3-N$ from 54 mg/L to 1,400 mg/L and alkalinity from 43 mg/L to 10,480 mg/L. The MLSS concentration reduced from an initial value of 2,650 mg/L down to 830 mg/L, then increased up to 8,340 mg/L. Though the volumetric loading rate varied in a range of $0.120\sim3.130$ kg $NH_3-N/m^3-day$, the F/M ratio showed a narrow range of $0.067\sim0.414$ kg $NH_3-N/kg$ MLSS-day. The average nitrification efficiency at each experimental stage resulted in the range of $35.2\sim100%$, and the maximum nitrification rate was 2.970 kg $N/m^3-day$ or 0.489 g N/g MLVSS-day. The nitrifiers' fraction of the MLVSS increased up to 100% from an initial value of 7.1% and the biofilm formed on the nonwoven fabric filter showed a very low nitrifiers' fraction of mere 2.2%. The growth yield of the MLSS and the alkalinity consumption rate were computed to be 0.117 g VSS/g N removed and 7.08 g alkalinity/g $NO_x^--N$ produced, respectively. Results of the research suggest that NFBR could be an adequate process for nitrification of wastewaters with high ammonia concentrations.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.8
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• pp.1028-1033
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• 2010

The effects of delta-aminolevulinic acid (DALA) or chito-oligosaccharide (COS) in layer diets on production performance, egg quality and hematological characteristics were investigated in this 8-week trial. Two hundred and seventy 27-week-old (Hy-Line brown) layers were randomly assigned to 5 treatments with 9 replications per treatment. Dietary treatments were i) Control (basal diet); ii) DALA1 (basal diet+DALA 2 mg/kg); iii) DALA2 (basal diet+DALA 4 mg/kg); iv) COS1 (basal diet+COS 100 mg/kg) and v) COS2 (basal diet+COS 200 mg/kg). In this study, no significant difference was observed in feed intake and egg shell quality (eggshell breaking strength and egg shell thickness) among treatments. The inclusion of DALA increased egg production during the first 4 weeks. Egg weight was increased in both DALA (quadratic, p<0.05) and COS (linear, p<0.05) treatments compared with the control treatment. Laying hens fed the DALA treatment had an increased yolk color unit (quadratic, p<0.05) and haugh unit (linear, p<0.05) compared with the control group. Similarly, these characteristics were also affected by COS treatments, with both values being linearly increased (p<0.05) in COS treatments compared with the control treatment. Additionally, birds fed DALA treatments significantly increased (quadratic, p<0.05) the number of RBC, WBC and lymphocytes compared with the control treatment. Dietary DALA supplementation linearly increased (p<0.05) the serum iron concentration at the end of the 8th week. The inclusion of COS increased (linear, p<0.05) the concentration of RBC, WBC and lymphocytes compared with the control treatment. In conclusion, dietary DALA at the lower dosage (2 mg/kg) could exert better effects in laying hens than higher dosage (4 mg/kg). Birds fed DALA supplemented diet had an increased iron availability, egg weight, eggshell quality and immunity. Moreover, the inclusion of COS (200 mg/kg) can increase egg weight, eggshell quality and immunity in laying hens. Therefore, both the utilization of COS and DALA could be considered as a new strategy for optimizing egg quality and health condition of laying hens.

• Journal of Nutrition and Health
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• v.31 no.1
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• pp.36-45
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• 1998

Dietary and other factors affecting bone density of 32 Korean healthy college women aged 19-23 years were assessed. Data for food and nutrient intake was obtained by a semiquantitiative food frequency questionnaire. Serum samples were anlayzed for total Ca, P, Ca++, PTH, calcitonin and 25-hydroxycholecalciferol , (25-OH-Vit D3) and BMDs of lumbar spine(L2-L4), femoral neck(FN), ward's triangle (WT) and trochanter(TR) were measured by an XR-series X-ray bone densitometer. Relationships between the factors and BMDs were analyzed by stepwise multiple regression analysis and Pearson's correlation coefficient(r). The results are summarized as follows. Mean daily intake of energy(86.1%), Ca(74.3%), vitamin A (53.75), Fe(49.75) and vitamin B$_2$(86.6%) were lower while other notrients incuding P(126%) were higher than the Korean RDA. The BMDs of lumbar spines and femurs ranged from 0.73g/$\textrm{cm}^2$ to 1.23g/$\textrm{cm}^2$and 0.48g/$\textrm{cm}^2$ to 1.04g/$\textrm{cm}^2$, respectively. Both protein and P intakes were inversely associated with serum total Ca. Furthermore, Ca intake as well as Ca/P ratio (Ca/P) were inversely associated with serum ionized Ca(Ca++) concentration. The intakes of protein P and Ca , however, were not significantly associated with the BMDs measured in this study. There were little association between BMDs and alcoholic beverage or caffeine consumption. The only significant association detected was a positive relationship between caffeine consumption and BMD of WT. It seemed to be noticeable that BMDs of L2-L$_4$, FN and WT were significantly inversely associated with serum P concentration. However, there was no significant association between BMDs and the levels of total Ca to Ca++ in serum. Body weight was positively associated with BMD of lumbar spine and BMI was also positively associated with BMDs of FN and WT. The subjects who had an early menarche appeared to have higher BMDs than those who had had a late mearche. According to stepwise multiple regression analysis. Menarche and BMI were stronger determinants of BMDs in the young women than was diet. P intake appeared to be a more potent dietary determinant than Ca intake. The three factors, menarche, BMI , and P intake , additionally accounted for 24% and 378% of the variance in BMDs of FN and L$_2$-L$_4$, respectively. Further investigation is necessary to determine the factors needed to increase serum P level which negatively affects. BMD in young Korean college women.

• Journal of the Korean earth science society
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• v.22 no.6
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• pp.480-490
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• 2001

The soil-air exchange processes of Hg were investigated from the Hari area of Kang Hwa Island during the late March 2001. In the course of our study, we determined the concentration gradients of Hg and combined these gradient data with micrometeorological components to derive its fluxes. Results of our study indicate that the concentration levels of Hg in the study area are notably lower than those typically found in urbanized areas of Korea. However, the computed fluxes were seen to be significantly larger for relatively remote areas, reaching over 200 ng/m$^2$/hr. Comparison of environmental conditions shows that the concentrations of most pollutant species including NO$_X$ and PM were significantly higher during emission, while meteorological conditions were characterized by high temperature and low humidity. Results of correlation analysis also indicate that such pollutants as hydrocarbons, nitrogen oxides, and PM generally exhibit strong positive correlations with Hg-related parameters during emission events, while such relationships were reversed during dry deposition events. The results of our present study suggest the possibility that the concentrations and fluxes of total gaseous Hg observed during deposition events can be influenced by the processes that are also important for the fine, rather than coarse, size fraction of particles.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.2
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• pp.226-233
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• 2010

Different dietary cereal sources and fat types in the lactation diet were evaluated to investigate their effects on reproductive performance, milk composition, blood metabolites and hormones in multiparous sows. Twenty-four sows were randomly assigned to one of four treatments according to a 2${\times}$2 factorial arrangement of treatments. Each treatment had 6 replicates comprising 1 sow. Two cereal (corn or wheat) and two fat (tallow or soybean oil) sources were used to prepare iso-caloric and iso-nitrogenous diets. Sows fed corn-based diets lost less body weight (p = 0.003) and backfat thickness (p = 0.034), consumed more feed (p = 0.032) and had shorter wean-to-estrus interval (p = 0.016) than sows fed wheat-based diets. Fewer piglets and lower body weight of piglets (p<0.05) at weaning were noted in sows fed wheat-based diets than in sows fed corn-based diets. However, no significant effects (p>0.05) of dietary fat source and its interaction with dietary cereal source on sow body condition and reproductive performance were observed during lactation. Feeding of a corn-based diet improved (p<0.05) sow milk total solid, protein and fat, increased blood urea nitrogen (p = 0.032) and triglyceride (p = 0.018), and decreased blood creatinine (p = 0.011) concentration at weaning when compared with sows fed wheatbased diets. Sows fed corn-based diets had higher concentration of insulin (p = 0.048) and LH (p<0.05) at weaning than sows fed wheatbased diets. The results indicate that feeding corn-based diets to lactating sows improved sow body condition and reproductive performance compared with wheat-based diets regardless of fat sources.

• Journal of Conservation Science
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• v.27 no.3
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• pp.243-250
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• 2011

Seven glass beads from Bupwha-ri site, Yeongdong dated Joseon dynasty were analyzed with SEM/EDS and X-ray diffraction methods. Six samples were classified to potash glass system($K_2O-CaO-SiO_2$) with HCA(High CaO and $Al_2O_3$) and high concentration of MgO suggested raw materials to plant ashes. Especially one sample from tomb no. 8 was highly different concentration of $K_2O$ and MgO with others. It was shown that they were different sources of raw materials. Mostly coloring agents of potash glasses were owing to Fe and Cu. One sample was found to lead glass system(PbO-$SiO_2$) with 12% PbO. The content of PbO was differentiated with other lead glasses since we analyzed so far. It needs more study for compositions of lead glasses with regions and ages.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.4
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• pp.136-147
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• 2005

Leachate from landfill sites contains high organics, chloride and ammonium nitrogen in concentration which might be potentially major pollutants to surface and groundwater environment. Most of landfill leachate treatment plants in Korea consist of biological processes to remove BOD and nitrogen. However, the efficiencies of refractory organics removal, nitrification and denitrification have not met frequently the national effluent regulation of wastewater treatment facility, especially in winter season. Simultaneous removal of organics and nitrogen from leachate is strongly necessitated to meet the national regulation on effluents from leachate treatment facilities. The intermittently aerated biological activated carbon fluidized bed(IABACFB) process was applied to treat real landfill leachates containing refractory organics and high concentration of ammonium nitrogen. The IABACFB reactor consisted of a single bed in which BAC fluidizing and an aerating column. The fluidized bed is intermittently aerated through the blower located at the aerating column. Experiments were performed to evaluate the applicability of Intermittently Aerated BACFB for simultaneous removal of refractory organic carbon and ammonium nitrogen of leachate. Organics and ammonia nitrogen($NH{_4}{^+}-N$)are oxidized during the aerobic stage, and nitrite-nitrate nitrogen($NO{_x}{^-}-N$) are removed to nitrogen gas through denitrification reaction during anoxic state. The IABACFB reactor condition reached a steady state within 40 days since the reactors had been operated. The blowing mode of 60 min.-On/60 min.-OFF is more compatible to remove TOC and ($NH{_4}{^+}-N$) operated. The blowing mode of 60 min.-On/60 min.-OFF is more compatible to remove TOC and ($NH{_4}{^+}-N$) simultaneously than the mode of 30 min.-On/90 min.-OFF. The average removal efficiencies of TOC, the refractory organic carbon, and the average efficiencies of nitrification and denitrification were 90%, 75%, 80%, 95%, respectively.

• Applied Microscopy
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• v.34 no.1
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• pp.43-50
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• 2004

In this study, we examined effects of environmental endocrine disruptor bisphenol A on the reproduction of Xiphophorus maculatus. We exposed the males of X. maculatus to the bisphenol A adjusted to the various concentrations such as 100 ppb, 200 ppb, 400 ppb and 800 ppb for 3 months for the experimental groups and then inbreeded with normal females that was not any treated. We counted the number of second generation for confirmation of fertilizing ability of first generation. Also, we observed the ratios of female and male, the abnormality and mortality, and spermatogenesis of the second generation was exposed to bisphenol A for 6 months. As the result, the number of fry in the second generation was $11.50{\pm}2.22$ in 100 ppb, $6.40{\pm}2.76$ in 200 ppb, $5.70{\pm}1.34$ in 400 ppb and $3.70{\pm}2.11$ in 800 ppb at the experimental groups while it was $19.00{\pm}3.02$ at the control group which was not treated with bisphenol A. This result showed that the experimental groups exhibited a decreasing tendency according to the increase of bisphenol A concentration comparing with the control group. The ratio of female and male of the second generation had no relations with the concentration of bisphenol A, and the ratios of abnormality and mortality were 0%. The spermatogenesis of experimental groups was normal in 800 ppb as well as 100 ppb, 200 ppb, 400 ppb after even 6 months.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.200-200
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• 2010

In recent times, metal oxide semiconductors thin films transistor (TFT), such as zinc and indium based oxide TFTs, have attracted considerable attention because of their several advantageous electrical and optical properties. There are many deposition methods for fabrication of ZnO-based materials such as chemical vapor deposition, RF/DC sputtering and pulsed laser deposition. However, these vacuum process require expensive equipment and result in high manufacturing costs. Also, the methods is difficult to fabricate various multicomponent oxide semiconductor. Recently, several groups report solution processed metal oxide TFTs for low cost and non vacuum process. In this study, we have newly developed solution-processed TFTs based on Ti-related multi-component transparent oxide, i. e., InTiO as the active layer. We propose new multicomponent oxide, Titanium indium oxide(TiInO), to fabricate the high performance TFT through the sol-gel method. We investigated the influence of relative compositions of Ti on the electrical properties. Indium nitrate hydrate [$In(NO^3).xH_2O$] and Titanium isobutoxide [$C_{16}H_{36}O_4Ti$] were dissolved in acetylacetone. Then monoethanolamine (MEA) and acetic acid ($CH_3COOH$) were added to the solution. The molar concentration of indium was kept as 0.1 mol concentration and the amount of Ti was varied according to weighting percent (0, 5, 10%). The complex solutions become clear and homogeneous after stirring for 24 hours. Heavily boron (p+) doped Si wafer with 100nm thermally grown $SiO_2$ serve as the gate and gate dielectric of the TFT, respectively. TiInO thin films were deposited using the sol-gel solution by the spin-coating method. After coating, the films annealed in a tube furnace at $500^{\circ}C$ for 1hour under oxygen ambient. The 5% Ti-doped InO TFT had a field-effect mobility $1.15cm^2/V{\cdot}S$, a threshold voltage of 4.73 V, an on/off current ratio grater than $10^7$, and a subthreshold slop of 0.49 V/dec. The 10% Ti-doped InO TFT had a field-effect mobility $1.03\;cm^2/V{\cdot}S$, a threshold voltage of 1.87 V, an on/off current ration grater than $10^7$, and a subthreshold slop of 0.67 V/dec.