• Environmental Engineering Research
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• v.22 no.1
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• pp.12-18
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• 2017

Struvite precipitation has been proven to be an effective method in removing and recovering ammonia nitrogen (N) and phosphate phosphorus (P) from wastewater. In this study, effects of pH, molar ratios and pre-treatment of effluent of anaerobically digested swine wastewater were investigated to improve struvite crystallization. The magnesium : ammonium : phosphate ratio of 1.2 : 1.0 : 1.0 was found to be optimal, yet the molar ratio in the wastewater was 1 : 74.9 : 1.8. From the analysis, the optimum pH was between 8.0 and 9.0 for maximal phosphate P release and from 8.0 to 10.0 for maximal ammonia N and phosphate P removal from real wastewater. Analysis from Visual MINTEQ predicted the pH range of 7-11 for ammonia N and phosphate P removal and recovery as struvite. For pre-treatment, microwave pre-treatment was ineffective for phosphate P release but ultrasound pre-treatment showed up to 77.4% phosphate P release at 1,000 kJ/L of energy dose. Precipitates analysis showed that phosphorus and magnesium in the collected precipitate had almost same values as theoretical values, but the ammonia content was less than the theoretical value.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.1066-1071
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• 2010

To evaluate the effect of horticultural therapy (HT) on the emotional improvement of depressed patients, computer-based heart rate variability (HRV) was compared with self-report scale (SRS) known as existing subjective evaluation method. SRS included four test areas: mental stress scale (MSS), physical stress scale (PSS), Beck anxiety inventory (BAI), and Beck depression inventory (BDI). HRV was itemized into four parameters: standard deviation of the N-N intervals (SDNN), square root of mean squared difference of successive N-N intervals (RMSSD), total power (TP), and low-frequency/high-frequency ratio (LF/HF ratio). Thirty patients with depression at the same mental hospital participated in this study. 15 patients of the treatment group received HT once a week for three months, but the control group did not during the same period. As a result, the emotional improvement in treatment group was clearly identified through HRV as well as SRS. The significant difference was shown at three test areas (MSS, BAI, and BDI, $p$ < 0.001) in SRS and at one parameter (total power, $p$ < 0.05) in HRV. There was noticeable increase in SDNN, RMSSD, and LF/HF ratio in treatment group after HT activity, but no significant difference. Although all parameters of HRV did not show significance, the possibility of HRV as an objective evaluation method to HT was recognized in this study. These results also implied that HT was efficient in the mental and physical regeneration of the depressed patients in both subjective and objective evaluation methods.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.11
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• pp.1608-1614
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• 2014

The objective of this study was to investigate the different dietary ratios of n-6 to n-3 (n-6/n-3) fatty acid (FA) on performance and n-6/n-3 FA in muscles of broiler chickens. A total of 300 one-day-old Cobb chicks were randomly assigned to 3 treatments of 10 replicates in each (10 birds/replicate). Birds were fed on a corn-soybean meal-based diet containing 1% oil during starter (day 1 to 21) and 2% oil during finisher (day 22 to 39) phases, respectively. Treatments of high, medium and low dietary n-6/n-3 FA were formulated by replacing rice bran oil with linseed oil to achieve n-6/n-3 FA close to >20:1, 10:1 and 5:1, respectively. Average daily gain, average daily feed intake, and feed conversion ratio were similar (p>0.05) among the treatments. Serum glucose, cholesterol and triglycerides concentrations were not affected (p>0.05) by dietary treatments. In breast, concentration of C18:3n-3 was significantly greater (p = 0.001) for medium and low vs high n-6/n-3 FA, while concentrations of C20:5n-3, C22:6n-3, total n-3 FA, and n-6/n-3 FA were significantly higher for low vs medium, and medium vs high dietary n-6/n-3 FA. In contrast, concentrations of C18:2 and mono-unsaturated FA (MUFA) were lower for low vs high dietary n-6/n-3 FA. In thigh muscles, concentrations of C20:5n-3 were higher (p<0.05) for medium and low vs high dietary n-6/n-3 FA, and concentrations of C18:3n-3, C22:6, and n-3 FA were greater (p<0.05) for medium vs high, low vs medium dietary n-6/n-3 FA. However, concentrations of C18:1, MUFA, n-6/n-3 were lower (p<0.05) for low and medium vs high dietary n-6/n-3 FA. In conclusion, lowering the dietary n-6/n-3 FA did not affect the performance of chickens, but enhanced beneficial long-chain n-3 FA and decreased n-6/n-3 FA in chicken breast and thigh, which could be advantageous for obtaining healthy chicken products.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.105-108
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• 2011

Newly-developed fabrication of a p-n heterojunction diode constructed with a p-Si nanowire (NW) and an n-ZnO nanoparticle (NP) thin-film by the dielectrophoresis (DEP) technique is demonstrated in this study. With the bias of 20 Vp-p at the input frequency of 1 MHz, the most efficient assembly of the n-ZnO NPs is shown for the fabrication of the p-n heterojunction diode with a p-Si NW. The p-n heterojunction diode fabricated in this study represents current rectifying characteristics with the turn on voltage of 1.1 V. The diode can be applied to the fabrication of optoelectrical devices such as photodetectors, light-emitting diodes (LEDs), or solar cells based on the high conductivity of the NW and the high surface to volume ratio of the NP thin film.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.2
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• pp.76-88
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• 2012

In order to investigate the distribution of water masses and spatio-temporal variation of nutrients in the coastal areas of Gangwon province of the Korean East Sea, a survey of the physico-chemical parameters (temperature and salinity) and nutrients ($NO_2$-N, $NO_3$-N, $NH_4$-N, $PO_4$-P, and $SiO_2$-Si) was carried out at 5 locations (Goseong, Sokcho, Yangyang, Gangneung, and Donghae) in February, May, August, and November 2009. The water masses included in the study area were divided into 4 groups; 1) Tsushima Surface Water (TSW), 2) Tsushima Middle Water (TMW), 3) North Korean Cold Water (NKCW), and 4) East Sea Proper Water (ESPW). The distribution of water masses was affected by the change of season. In February, surface water was derived from the TMW. The TSW was not observed in May, but only observed in August. In November, as the influence of the TSW weakened, that of the NKCW strengthened. Considering the vertical profiles of nutrients, the concentrations in all the seasons were very low within the surface water, but increased rapidly near the thermocline. Most of nutrient concentrations, except for dissolved silicate, remained constant below the depth of 200 m. However, the dissolved silicate concentration increased with depth, suggesting that silicate has a delayed regenerative pattern. The ESPW had the highest nutrient concentration, followed by the NKCW, TMW, and TSW. In February, May, and November, the N/P ratio in most of the water masses was similar to or larger than the Redfield ratio, indicating that nitrogenous nutrients did not act as a limiting factor for phytoplankton growth. However, in August, the N/P ratio in the TSW was less than the Redfield ratio, and the concentration of $NO_2$-N+$NO_3$-N was 0.86 ${\mu}m$, indicating that nitrogenous nutrients did act as a limiting factor for phytoplankton growth in the study area.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.338.2-338.2
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• 2016

Al doped ZnO (AZO) thin films were deposited on Si substrates with rod-shaped-surface by pulsed laser deposition method (PLD). Si-rods were prepared through chemical etching. To analyze the influence on the formation of the rod structure, samples with various chemical etching conditions such as AgNO3/HF ratio, etching time, and solution temperature were prepared. The morphology of Si-rod structures were examined by FE-SEM. Fig. 1 shows a typical structure of n-AZO/p-Si-rod juncions. The fabricated n-AZO/p-Si-rod devices exhibited p-n diode current-voltage characteristics. We compared the I-V characteristics of n-AZO/p-Si-rod devices with the samples without Si-rod structure.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.1
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• pp.84-93
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• 2004

This study was performed : 1) to find the suitable HRT(hydralic retention time), 2) to evaluate the effects of the ratio of mixing/aeration time and injection time of external carbon source, for the removal of organics, nitrogen and phosphorus in swine wastewater by SBR(sequencing batch reactor process), which is one of the biological treatment process. The result of this study were summarized as follows : (1) As the ratio of mixing/aeration time was higher, $NH_4{^+}-N$ removal efficiency was increased and it was increased with increasing injection time of external carbon source because nitrification was affected by denitrification microbes propagation when injection time of external carbon soruce was shorted. T-N removal efficiency was increased with increasing the ratio of mixing/aeration time and injection time of external carbon source. (2) The T-P removal efficiency showed a great difference in each operating condition, and it was increased with increasing the ratio of mixing/aeration time increased and when the injection time of external carbon source was shorted because denitrification was done with effect by denitrification microbes propagation. (3) The highest removal efficiency of organic and nitrogen were obtained by the operating condition of Run 4-1(the ratio of mixing/aeration time : 16.5/5.5, injection time of external carbon source : 15hours) and T-P were obtained by the operation condition of Run 4-2(the ratio of mixing/aeration time : 16.5/5.5, injection time of external carbon source : 3hours), and efficiency(effluent concentration)of $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, T-N and T-P in the treated water was 96.1%, 87.7%, 90.6%, 86.6% and 84.5%, respectively.

• ALGAE
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• v.22 no.3
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• pp.235-240
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• 2007

The red tide-causing flagellate Chattonella anticfua can cause mass fish kills by their clogging in fish gills. Thisstudy examined the nutrient requirements of C. antiqua isolated from Korea. C. anticfua displayed maximum growthat the day five, followed by a decrease in cell density. Nitrate and nitrite were the preferred nitrogen sources, alonewith adenosine diphosphate for phosphorus compounds. In medium that contained ammonium, a significantdecrease in cell density was observed. Half-saturation constants, Ks, calculated from the maximum growth ratewere 4.94 U|M for NC>3 and 0.79 flM for P04. The growth of C. antiqua was not within the function of the N:P ratio (RU= 0.29). With an N:P ratio as low as 10, the increase in cell density was apparent, with a higher division rate. At lev-els above 50 fiM of NaNOg or 8 ;uM of NaHUPCU, the growth rates were somewhat decreased. Phosphate was thelimiting factor for C. antiqua growth since the starvation of phosphate had brought about a rapid decrease in celldensity in semi-continuous culture. Studies about the temporal modification of the efficiency of nitrate or phosphateuptake may be necessary to explain the bloom dynamics of C. antiaua.

• Journal of the Korean Wood Science and Technology
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• v.21 no.3
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• pp.87-93
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• 1993

This study was undertaken to investigate the characteristics and the productivities of lignin olytic enzymes: laccase (Lac) and Mn-dependent peroxidase (MnP) from Coriolus versicolor and Lentinus edodes respectively. Enzymes were isolated from cultural filterates and purified according to the standard methods. These enzymes showed one band in SDS-PAGE and their molecular weights were found 62,000 and 45,000 dalton respectively. Polyclonal antibodies against Lac and MnP were raised against mouse. In the ELISA (enzyme-linked immunosorbent assay), Lac and MnP-antiserum produced a strong positive reaction with Lac and MnP antigen($A_{405}$=2.50 and 3.53 respectively). The sera to negative (S/N) ratio was determined by the dividing the mean absorbance of antibodies by the corresponding diluted samples from normal mouse serum. The sera produced showed 2 times more positive reaction in S/N ratio than negative sera.

• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.617-625
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• 2009

The primary purpose of this study was to compare the hamstring-to-quadriceps strength(H/Q) ratios in collegiate soccer players and normal age-matched healthy students, and the secondary purpose was to investigate the changes in the H/Q ratio according to the degree of knee flexion. Twenty-five subjects volunteered to participate in this study. The study group comprised 12 healthy male collegiate soccer players, and the control group, 13 healthy age-matched male collegiate students. The modified N-K table was used for isometric strength measurement(unit: N). Mann-Whitney tests were performed to determine the differences in the H/Q ratios of soccer players and age-matched students at different knee flexion angles of the dominant leg. The strength of the hamstring muscle in the study group was significantly lower than that observed in the control group at knee flexion angles of $60^{\circ}$ (p<.001), $90^{\circ}$ (p<.01), and $120^{\circ}$ (p<05). The strength of the quadriceps muscle in the study group was significantly higher than that observed in the control group at flexion angles of $30^{\circ}$ (p<.001) and $60^{\circ}$ (p<.05). The H/Q ratios in the study and control groups differed significantly at all angles ($60^{\circ}$, p<.001, $90^{\circ}$, p<.001 and $120^{\circ}$, p<.001).