• Journal of Environmental Impact Assessment
• /
• v.8 no.1
• /
• pp.93-105
• /
• 1999

Lately water quality of Daechong Reservoir has become more eutrophicated than ever before and there has been much concern over especially the eutrophication of the embayment near Daejon and Chongju Water Intake Tower every summer. The purpose of this study is to predict the impact of change in the pollutant loading, flowrate, nitrogen and phosphorus release from sediment, SOD(sediment oxygen demand) upon the water quality of Daechong Reservoir by WASP5/EUTR05 in order to suggest water quality management alternatives. The data of Sep. 1995 were used for the calibration of the model and those of Sep. 1997 was for verification. The result of the modeling can be summarized as follows. 1. The 50% increase(decrease) of pollutant loading has caused that of T-N concentration by 0.10-0.14 mg/l, T-P concentration by 0.003-0.005 mg/l, and CBOD concentration by 0.16-0.18 mg/l. But the ratio of DO change by the change of pollutant loading was relatively small. 2. The sensitivity test of NH4 flux to T-N and that of P04 flux to T-P shows that T-N and T-P concentration were changed more in the epilimnion segments (SEG4, SEG5, SEG6, SEG7) than the other segments. As SOD increases, DO was predicted to decrease more especially in the hypolimnion (SEG9-SEG14). 3. As flowrate increase, the concentration of T-N, T-P, and CBOD were predicted to decrease, but DO concentration increased especially in the hypolimnion segments(SEG11, SEG12, SEG13, and SEG14). As the flowrate changed from $119m^3/sec$ to $50m^3/sec$, the concentration of T-N and CBOD in the hypolimnion was predicted to decrease.

• Bulletin of the Korean Chemical Society
• /
• v.5 no.6
• /
• pp.226-230
• /
• 1984

LIS's of cis and trans-methyl-2-phenylcyclopropanecarboxylate, cis and trans-t-butyl-2-phenylcyclopropanecarboxylate, cis and trans-N,N-dimethylcyclopropanecarboxamide, trans-2-phenylcyclopropyl methyl ketone and trans-2-phenylcyclopropyl t-butyl ketone have been studied. The LIS's hold the McConnell-Robertson relation and are mainly influenced by the steric effect. LIS's of trans isomers are larger than those of cis isomers. In trans isomers, the LIS's decrease in the following order: methyl ketone > methyl ester > N,N-dimethyl amide > t-butyl ketone${\sim}$t-butyl ester.

• Journal of Environmental Health Sciences
• /
• v.29 no.3
• /
• pp.59-64
• /
• 2003

This study was conducted to investigate anoxic-RBC-anoxic-RBC process and its application to remove biologically organics and nitrogen. BOD and total-nitrogen(T-N) removal efficiencies were decreased as volumetric loading rate increased. But, the removal efficiency changes of T-N were little, as compared to BOD. Increase of internal recycle rate had few affect of BOD and T-N removal rates. Also, influent allocation(to 2nd anoxic reactor) had few affect of BOD removal efficiency rate. However, when the influent allocation rate was 30%, T-N removal efficiency was increased to 84.1 %. BOD/N ratio applied to 2nd anoxic reactor was increased to range of 3.65-4.37 as influent allocation rate increased to range 20∼35%. But, it might also cause adverse effect such as decrease of denitrification rate in excessive influent allocation rate.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.1
• /
• pp.145-152
• /
• 2000

X-ray diffraction method detects change of crystal lattice distance under material surface using diffraction angle 2$\theta$. This technique can be applied to the behavior on slip band and micro crack due to material degradation. The relation between half-value breadth and number of cycle has three stages which constitute rapid decrease in initial number of cycles, slight decrease in middle number of cycles and rapid decrease in final number of cycles. The ratio of half-value breadth takes a constant value on B/B$_{0}$-N diagram with loading condition except early part of fatigue life. The ratio of half-value breadth B/B$_{0}$ with respect to number of cycle to failure N$_{f}$ has linear behavior on B/B$_{0}$-log N$_{f}$ diagram. Therefore, in this paper the estimation of fatigue life by average gradient method has much less estimated mean error than the estimation of fatigue life by log B/B$_{0}$-log N/N$_{f}$ relation.elation.ation.

• Clean Technology
• /
• v.10 no.2
• /
• pp.111-120
• /
• 2004

Manufacturing with a chemical for eco-friendly leather for nitrogen decrease of leather falling hair process waste water and the falling hair process that a number to decrease with sulfuration water decrease, a pollution load of COD, BOD. In this study manufactured lining agent and the unhairing assist product which did urea, mercaptan by basic matter. As a result of having dealt in hair saving process, compared, and was recalled by the existing hair burning process recovered hair, increased approximately 2times. Grain state to influence the yield that was quality of leather and an index of productivity evaluation, an improvement of contraction phenomenon (drawing) were possible. Is increased going seal, tear strength property of matter and softness and touch leather native nature in wet blue. Also, it is possible confirmation with decrease being more possible than about 50% COD, T-N density in a hair saving waste water.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.5
• /
• pp.483-491
• /
• 1992

Plasma silicon oxynitride film has been applied as a final passivation layer for semiconductor devices, because it has high resistance to humidity and prevents from alkali ion's penetration, and has low film stress. Structure properties of plasma silicon oxynitride film have been studied experimentally by the use of FT-IR, AES, stress gauge and ellipsometry. In this experiment,Si-N bonds increase as NS12TO/(NS12TO+NHS13T) gas ratio increases. Peaks of Si-N bond, Si-H bond and N-H bond were shifted to high wavenumber according to NS12TO/(NS12TO+NHS13T) gas ratio increase. Absorption peaks of Si-H bond were decreased by furnace anneal at 90$0^{\circ}C$. The atomic composition of film represents that oxygen atoms increase as NS12TO/(NS12TO+NHS13T) gas ratio increases, to the contrary, nitrogen atoms decrease.

• Journal of Astronomy and Space Sciences
• /
• v.25 no.2
• /
• pp.149-156
• /
• 2008

Forbush Decreases (FDs) are representative events of abrupt decrease in galactic cosmic ray intensity. They are known to be strongly associated with solar wind events such as interplanetary shock (IP shock) and magnetic cloud (MC). In order to examine effectiveness of the MC on FDs, I studied the 44 MCs that occurred during the 2 years from 1998 to 1999 and investigated the properties of interplanetary magnetic field (IMF) and solar wind. As a result, I found that 11 out of 44 MCs are associated with the FDs. In particularly, it is noted that the FDs are driven by the IP shock sheaths which are associated with over 13 nT of IMF magnitude, 3 nT of IMF turbulence, and 550km/s of solar wind speed. This result indicates that magnetic cloud and its interplanetary shock sheath work as a modulator of the cosmic ray intensity.

• Journal of Korean Dental Science
• /
• v.13 no.1
• /
• pp.11-20
• /
• 2020

Purpose: This study sought to identify differences in hard and soft tissue chin profile changes in skeletal Class III patients after bimaxillary surgery, with or without advancement genioplasty. Materials and Methods: The retrospective study was conducted based on cephalometric analysis of skeletal and soft tissue variables. Lateral cephalograms taken at 3 different time points were utilized: pre-operation (T0), immediately post-operation (T1), and at least 6 months (11.0±2.6 months) post-operation (T2). The 2 groups were matched for sample size (n=20 each). Data were analyzed using independent t-tests with Bonferroni correction. Result: Group N (bimaxillary surgery alone) and Group G (bimaxillary surgery with an advancement genioplasty by horizontal sliding osteotomy) did not differ significantly in terms of demographic characteristics. The soft tissue chin thickness of Group G increased more after surgery, followed by a greater decrease during the postoperative period, and was eventually not significantly different from Group N at T2. On the other hand, the mentolabial sulcus depth of Group G (5.5±1.3 mm) was significantly greater than that of Group N (4.4±0.9 mm) (P=0.006) at T2. Conclusion: Although Group G showed a statistically significantly greater decrease in soft tissue chin thickness during the postoperative period, there were no significant intergroup differences in the chin profile for at least 6 months after the surgery, except for the mentolabial sulcus depth, which was greater in Group G than in Group N.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.43 no.6
• /
• pp.163-173
• /
• 2001

This study describes the characteristics of concentrations of pollutants such as total nitrogen(T-N), total phosphorous(T-P), and chemical oxygen demand(COD) at paddy areas during 2-year irrigation periods. The most common order in average concentrations of T-P and COD is podded water > irrigation(or drainage) water > percolated water. Most of pollutants concentrations in drainage water are lower than those in irrigation water after early July due to large uptake of pollutants by rice crop and denitrification. The exponential L (load)-Q(discharge) equations for classified irrigation periods are significant at 0.001 level for irrigation and drainage waters. For drainage water, the concentrations of T-N and COD slightly decrease with discharge, while the T-P concentrations slightly increase with discharge.

• The Korean Journal of Zoology
• /
• v.33 no.3
• /
• pp.247-254
• /
• 1990

Chicken monocular head and eye optokinetic nystagmus (OKN) were observed by coil recordings after intravitreal administration of GABA antagonists (picrotoxin and bicuculline) into the opened and closed eye. Before injection of drugs the chicken displayed an OKN for T-N stimulation being more efficient in evoking this visuomotor reflex than for N-T stimulation. The injection of GABA antagonist into the opened eye provoked a decrease or disappearance of the head and eye OKN. On the other hand, the injection of GABA antagonist into the closed eye, the head and eye OKN augmented. Thus, GABA antagonist abolished the directional asymmetry of the head and eye OKN, indicating the involvement of GABAergic mechanisms in the inhibition of the N-T component of the monocular OKN.