• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.25-31
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• 2011

In this study, model-based $NH_4-N$ predictive control algorithm by using influent pattern was developed and evaluated for effective control application in $A^2/O$ process. A pilot-scale $A^2/O$process at S wastewater treatment plant in B city was selected. The behaviors of organic, nitrogen and phosphorous in the biological reactors were described by using the modified ASM3+Bio-P model. A one-dimensional double exponential function model was selected for modeling of the secondary settlers. The effluent $NH_4-N$ concentration on the next day was predicted according to model-based simulation by using influent pattern. After the objective effluent quality and simulation result were compared, the optimal operational condition which able to meet the objective effluent quality was deduced through repetitive simulation. Next the effluent $NH_4-N$ control schedule was generated by using the optimal operational condition and this control schedule on the next day was applied in pilot-scale $A^2/O$ process. DO concentration in aerobic reactor in predictive control algorithm was selected as the manipulated variable. Without control case and with control case were compared to confirm the control applicability and the study of the applied $NH_4-N$control schedule in summer and winter was performed to confirm the seasonal effect. In this result, the effluent $NH_4-N$concentration without control case was exceeded the objective effluent quality. However the effluent $NH_4-N$ concentration with control case was not exceeded the objective effluent quality both summer and winter season. As compared in case of without predictive control algorithm, in case of application of predictive control algorithm, the RPM of air blower was increased about 9.1%, however the effluent $NH_4-N$ concentration was decreased about 45.2%. Therefore it was concluded that the developed predictive control algorithm to the effluent $NH_4-N$ in this study was properly applied in a full-scale wastewater treatment process and was more efficient in aspect to stable effluent.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.153-157
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• 2014

Purpose: SLE (systemic lupus erythematosus) is an inflammatory autoimmune disease, characterized by various autoantibody. The detection of Anti double-stranded DNA (Anti-ds DNA) is important in the diagnostics of SLE, and include the American College of Rheumatology (ACR) diagnostic criteria for SLE. Also SLE disease activity and correlativity with the level Anti-ds DNA antibody have been reported and Anti-ds DNA antibody quantitative test is very useful for tracing before and after SLE treatment. When These Anti-ds DNA antibody test (Farr assay: $^{125}I$ labeled ds-DNA and bound Anti-ds DNA antibodies complex in serum is precipitated by ammonium sulfate and used to centrifugation, measured it) inhaled supernatant after centrifugation, a lipemic specimen does not facilitate the formation of precipitate and also occurs situation was inhaled with precipitate. To solve these problems, The Influence of the degree of lipemic specimen was evaluated. Materials and Methods: September 2012 to February 2013, We selected lipemic samples (n=81) of specimen commissioned by Anti-ds DNA antibody test. Lipemic samples were done pre-treatment (high-speed centrifugation: 14,000 rpm 5 mins) used a micro-centrifuge (Eppendorf Model 5415D). At the same time lipemic specimen and pre-treatment samples were performed Anti-ds DNA antibody test (Anti-ds DNA kit, Trinity Biotech, Ireland). Statistical analysis were analyzed Pearson's correlation coefficients and regression and paired t-test, and Difference (%). Results: Experimental group 1 (Lipemic Specimen Anti-ds DNA Ab concentration ${\leq}7IU/mL$) at y=0.368X+4.732, $R^2=0.023$, Pearson's correlation coefficient was 0.154, paired t-test (P=0.003), Difference (%) mean 65.7 and showed a statistically significant difference. Experimental group 2 (Lipemic Specimen Anti-ds DNA Ab concentration ${\geq}8IU/mL$) at y=0.983X+0.298, $R^2=0.994$, Pearson's correlation coefficient showed 0.997, paired t-test (P=0.181), Difference (%) mean -5.53 made no statistically significant difference. Conclusion: Lipemic sample of low Anti-ds DNA Ab concentration (2.5-7 IU/mL) and the result is obtained pre-treatment (high-speed centrifugation: 14,000 rpm 5 mins) were made a significant difference statistically. Anti-ds DNA is one of the primary auto-antibodies present in patients with SLE, and remain an important diagnostic test for SLE. Therefore, we recommend preprocessing (high-speed centrifugation: 14,000 rpm 5 mins) in order to exclude the influence of lipemic specimen.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.283-288
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• 2019

Catalytic removal of sulfur compounds from heavy naphtha (HN) was investigated using a combination of an oxidation process using hydrogen peroxide and an adsorption process using granulated activated carbon (GAC) and white eggshell (WES). This study investigated the impact of changing several operating parameters on the desulfurization efficiency. Specifically, the volume ratio of $H_2O_2$ to HN (0.01~0.05), agitation speed ($U_{speed}$) of the water bath shaker ($100-500{\pm}1rpm$), pH of sulfur solution (1~5), amount of adsorbent (0.1~2.5 g), desulfurization temperature ($25{\sim}85{\pm}1^{\circ}C$) and contact time (10~180 minutes) were examined. The results indicate that the desulfurization efficiency resulting from catalytic and adsorption processes of GAC is better than that of WES for oxidation and removing sulfur compounds from HN due to its high surface area. The desulfurization efficiency depends strongly on all investigated operating parameters. The maximum removal efficiency of GAC and WES achieved by this study was 86 and 65, respectively.

• Korean Journal of Crystallography
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• v.6 no.1
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• pp.1-13
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• 1995

Cr:A12O3 and Ti:A12O3 single crystals were grown by Czochralski method, and the effects of crystal growth parameters such as pulling rate, rotation rate, dopant and growth atmosphere on crystal quality were investigated. And spectroscopic properties including lasing efficiency were also measured. Single crystals, sized of 20mm in diameter and 100-135mm in length, were successfully grown from the seed of <001> direction. With the doping level of 0.5w/o Cr2O3, pulling rate 2.0mm/hr, rotation rate of 30rpm and inert atmosphere by nitrogen gas, high quality crystals of Cr:A12O3 were grown. While in case of Ti:A12O3 crystals, high quality crystals were grown under the conditions of the doping level of 0.25w/o TiO2, pulling rate of 1.5mm/hr, rotation rate of 30rpm and reducing atmosphere by hydrogen - nitrogen mixed gas. It was confirmed that Cr3+ ion which maintains its ionoc valence during growth easily de-bubbled than Ti4+ ion which changes its valence, Fe3+ ion also has do-bubbling effect to Ti:A12O3 crystal and the reducing atmosphere by 90% N2 - 10% H2 mixed gas gave effective result on the changing of Ti4+ to Ti3+ and de-bubbling. As a result of spectroscopic measurements of Cr:A12O3 crystal, 4A2 →4F2 and 4F1 absorption transitions and E →4A2(R1) and 2A →4A2(R2) fluorenscence transitions were confirmed. And it was measured that wavelengths of laser R1 and R2 transitions were 696±5nm and 692±5nm respectively, line width of these transitions were 12A, and life-time of fluorenscence was 152μsec. In case of Ti:A12O3 crystals, it was confirmed that absortion transition of 4T2→4E and fluorescence transition of 4E→4T2 with wide range of 650-1050nm was occured. And 147μsec of life-time of fluorescence, 125.4 of figure of merit and 9% of laser efficience were also measured.

• The Korean Journal of Mycology
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• v.2 no.1
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• pp.25-29
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• 1974

1. Penicillium sp. C 13-13 strain was obtained with the treatment of mutagenic agents(N.T.G.) and by single spore isolation method from the Penicillium sp. C8-14 strain, which was reported in the previous paper. 2. The above strain had a few spores and to obtain seed culture, it was cultured at $30^{\circ}C$ and initial pH $4.5{\sim}5.0$, with air rate 6l/min., and agitation 600 rpm for 48 hours in 10% wheat bran medium in 20l- Jar fermenter. When the broth that had above 70ml of mycelium was inoculated into wheat bran medium and incubated at $29{\sim}33^{\circ}C$ for 72 hrs, the cellulase activity of the koji was higher. 3. Adding calcium chloride and magnecium sulfate to the wheat bran medium to 1.5% and 0.015% respectively, the cellulase activity of the koji was higher than that of the control.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.795-800
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• 2002

Yb:$YCa_4O(BO_3)_3$ (Yb:YCOB) single crystal, in which the concentration of $Yb^{3+}$ ion 20 at%, was grown by the Czocharalski method using an iridium crucible under N2 atmosphere. The optimum growth parameters to get a high quality of single crystals were found to be 1.5∼2 mm/h of pulling rate and 10∼20 rpm of rotation rate. According to the results of spectroscopic properties, absorption edge of Yb:YCOB was 236 nm. Two strong absorption line due to $Yb^{3+}$ ions were observed at 900 and 975 nm. Thermal expansion coefficients of Yb:YCOB crystal along a, b and c crystallographic axes from 320 to 650 K were 12.1${\times}10^{-6}$/K, 5.9${\times}10^{-6}$/K, 12.9${\times}10^{-6}$/K, respectively. Specific heat was 0.162 $cal/g{\cdot}K$ at 330 K.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.42-50
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• 2008

Various researches to reduce weight of a vehicle are achieving. One of these researches is tendencious to manufacture the hollow piston rod using friction welding instead of solid one of the vehicle shock absorber. This study deals with the friction welding of SM45C to SM20C-pipe that is used normally in the vehicle shock absorber. The friction time was variable conditions under the conditions of spindle revolution of 2,000rpm, friction pressure of 55MPa, upset pressure of 75MPa, and upset time of 2.0seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests of friction weld were studied and so the results were as follows. When the friction time was l.5seconds under the conditions, the maximum tensile strength of the friction weld happened to be 837MPa, which is 113% of SM20C's tensile strength and 97% of SM45C's. The optimal welding conditions were n=2,000rpm, $P_1=55MPa$, $P_2=75MPa$, $t_1=1.5sec$, $t_2=2.0sec$ when the total upset length is 1.7mm.

• Tribology and Lubricants
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• v.6 no.1
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• pp.52-56
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• 1990

The Lubrication Mode of line contacts between the vane and camring in an oil hydraulic vane pump with intravanes has been investigated. Variations of the radial acting force of a vane were calculated from previously measured results of dynamic internal pressure in four chambers surrounding a vane, and variations of the lubrication mode were estimated in both the rotational speed range from 500 to 1500 rpm and in the delivery pressure range from 1 to14 Mpa. The results indicate the variations of the radial acting force. It is found that the regimes of lubrication in the vane tip contacts cover rigid-isoviscous to rigid-variable viscosities.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.6
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• pp.19-27
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• 1998

This study was investigated on the friction welding of A2024 aluminum alloy to SM45C carbon steel with insert metals. The tensile strength of welded joints, the hardness distribution of welds, the microstructure of welds and the tensile fracture surfaces were mainly investigated through this experiment. When aluminum alloy A6351 was used as insert metal, the maximum tensile strength of welded joint was obtained. In this case, the maximum joint efficiency was 76.2 percent of base metal. Optimal welding conditions were N=2,000rpm. $P_1$=40MPa, $P_2$, $t_1$=1.5 sec, $t_2$=5 sec.

• Journal of Welding and Joining
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• v.16 no.5
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• pp.48-55
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• 1998

This study was undertaken to investigate the friction welding of A2024-T6 aluminum alloy and SM45C carbon steel using insert metals. The relationships among the friction welding conditions, the tensile strength of joints, the hardness distribution of welds, the microstructure of welds and the tensile fracture surfaces were mainly investigated through this experiment. When the A6063-T5 aluminum alloy of insert metal was used, the maximum tensile strengh of joint was obtained. In this case, the maximum joint efficiency was 75.3 percent and in the case of unusing the insert metals, it was 37.7 percent. Optimal welding conditions were N=2000rpm, P$_1$=40MPa, P$_2$=140MPa, t$_1$=1.0sec and t$_2$=5sec.