• Environmental Engineering Research
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• v.21 no.2
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• pp.196-202
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• 2016

Membrane bioreactor (MBR) technology has previously been used by water industry to treat high salinity wastewater. In this study, an anoxic-oxic biofilm-membrane bioreactor (AOB-MBR) system has been developed to treat mustard tuber wastewater of 10% salinity (calculated as NaCl). To figure out the effects of operating conditions of the AOB-MBR on membrane fouling rate ($K_V$), response surface methodology was used to evaluate the interaction effect of the three key operational parameters, namely time interval for pump (t), aeration intensity ($U_{Gr}$) and transmembrane pressure (TMP). The optimal condition for lowest membrane fouling rate ($K_V$) was obtained: time interval was 4.0 min, aeration intensity was $14.6 m^3/(m^2{\cdot}h)$ and transmembrane pressure was 19.0 kPa. And under this condition, the treatment efficiency with different influent loads, i.e. 1.0, 1.9 and $3.3kgCODm^{-3}d^{-1}$ was researched. When the reactor influent load was less than $1.9kgCODm^{-3}d^{-1}$, the effluent could meet the third discharge standard of "Integrated Wastewater Discharge Standard". This study suggests that the model fitted by response surface methodology can predict accurately membrane fouling rate within the specified design space. And it is feasible to apply the AOB-MBR in the pickled mustard tuber factory, achieving satisfying effluent quality.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.660-662
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• 2018

With the increasing number of dog markets in modern society, dog owners are deeply rooted in our lives and affecting society. Following this trend, a variety of products have recently been introduced, and it is believed that they have not yet developed much in functional aspect of the post-cleaning system. Due to the busy social life of modern people in everyday life, there is no room to manage dogs in terms of time, cost and environment, which is causing problems. In order to avoid these problems, we are going to develop Eduardo, infrared sensor modules, and automatic pump systems. It is also designed to make it more convenient for users through a laxation pad automatic washing machine.

• Journal of environmental and Sanitary engineering
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• v.14 no.4
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• pp.117-123
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• 1999

The analytical instrument method was applied to analyze malodorous sulfur compounds emitted from industrial fields. Six factories and two sites which release malodorous substances into ambient air were selected to determine the level of hydrogen sulfide($H_2S$), methylmercaptan(MeSH), dimethyl sulfide($Me_2S$), and dimethyl disulfide($Me_2S_2$) using automated thermal desorption system (STD400) and GC-FPD in summer and fall seasons of 1999. The Air sampler for ATD400 uses a small pump to draw sample and a mass flow controller to adjust sample amount without using a dilution apparatus. The trap temperature of ATD400 reached to $-80^{\circ}$ by supplying liquid nitrogen and $H_2S$ can be analyzed under this condition. The recovery rates of $H_2S$, MeSH, $Me_2S$, and $Me_2S_2$ of odorous sulfur compounds standard were shown 98.2%, 93.6%, 98.2%, 99.4% respectively. The concentrations of $Me_2S$ at outside boundary of G market, L factory, and J factory were 0.018ppm, 0.021ppm, 0.032ppm in summer, respectively. The concentration of $H_2S$ at Nanjido landfill was 1.167ppm in summer, but that of $H_2S$ was not detected in fall because of soil covering. The concentration of H2S and $Me_2S_2$ at inside of Chonggye stream were 0.564ppm and 1.045ppm in summer, while those of H2S and Me2S2 were 0.285ppm and 0.465ppm in fall, respectively.

• Membrane Journal
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• v.26 no.1
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• pp.26-31
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• 2016

Polycaprolactone (PCL) has been fabricated into the membrane type scaffolds of 3 dimensional pore network for the tissue engineering applications by the blade method of salt (NaCl) leaching and solution casting. In this study, the experimental designs have each conditions of drying temperature, salt particle size, salt content. The modified dispensing pump connected up to homogenizing mixer system is used for mixing the $PCL/CHCl_3$ solution and NaCl particles. The membrane fabricated use by the film applicator to poured mixed solution on the glass plate. The great pore by NaCl particles and the small pore by the evaporated $CHCl_3$ in the frame wall of great pores are multiply formed in membrane scaffolds.

• Journal of IKEEE
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• v.18 no.1
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• pp.152-158
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• 2014

It is very important to supply the diesel fuel from fuel tank to combustion chamber in case of cold start procedure. the paraffin hydrocarbons are easily solidified at low fuel temperature and it can be blocking the fuel supply to the high pressure fuel pump. In order to reduce the fuel crystallization (Waxing), it have been used to develop not only cold flow additives but also the proper mounting design of fuel filter. Block heater in the fuel filter assembly have been also contained to improve the cold start and prevent blocking the fuel supply in Common Rail Direct Injection System. we can obtain the fuel pressure drop and fuel flow rate, power consumption of fuel heater to have the cold flow evaluation test with the saperated and composited fuel heater at the low ambient temperature, Due to evaluating cold flow performance of two block heater, we knew that composited package fuel heater was the excellent cold flow performance compared to separated type and obtained the parameters of cold flow.

• Journal of Power Electronics
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• v.17 no.1
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• pp.222-231
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• 2017

In this paper, a new architecture for a cost-effective power conditioning systems (PCS) using a single-sourced asymmetric cascaded H-bridge multilevel inverter (MLI) for photovoltaic (PV) applications is proposed. The asymmetric MLI topology has a reduced number of parts compared to the symmetrical type for the same number of voltage level. However, the modulation index threshold related to the drop in the number of levels of the inverter output is higher than that of the symmetrical MLI. This problem results in a modulation index limitation which is relatively higher than that of the symmetrical MLI. Hence, an extra voltage pre-regulator becomes a necessary component in the PCS under a wide operating bias variation. In addition to pre-stage voltage regulation for the constant MLI dc-links, another auxiliary pre-regulator should provide isolation and voltage balance among the multiple H-bridge cells in the asymmetrical MLI as well as the symmetrical ones. The proposed PCS uses a single-ended DC-DC converter topology with a coupled inductor and charge-pump circuit to satisfy all of the aforementioned requirements. Since the proposed integrated-type voltage pre-regulator circuit uses only a single MOSFET switch and a single magnetic component, the size and cost of the PCS is an optimal trade-off. In addition, the voltage balance between the separate H-bridge cells is automatically maintained by the number of turns in the coupled inductor transformer regardless of the duty cycle, which eliminates the need for an extra voltage regulator for the auxiliary H-bridge in MLIs. The voltage balance is also maintained under the discontinuous conduction mode (DCM). Thus, the PCS is also operational during light load conditions. The proposed architecture can apply the module-integrated converter (MIC) concept to perform distributed MPPT. The proposed architecture is analyzed and verified for a 7-level asymmetric MLI, using simulation results and a hardware implementation.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.53-59
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• 1998

Flow pattern of air-water two phase flow depends on the conditions of pressure drop, void fraction, and channel geometry. Drag reduction in the two phase flow can be applied to the transport of crude oil, phase change systems such as chemical reactor, pool and boiling flow, and to present cavitation which occurs in pump impellers. But the research on drag reduction in two phase flow is not intensively investigated. Therefore, experimental investigations have been carried out to analyze the drag reduction produced and void fraction by Co-polymer(A611p) addition in the two phase flow system. We find that the maximum point position of local void friction moves from the wall of the pipe to the center of the pipe when polymer concentration increases. Also we find that the polymer solution changes the characteristics of the two phase flow. And then we predict that it is closely related with the drag reduction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.8
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• pp.645-651
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• 2015

The objective of this study is to experimentally investigate the effect of design parameter on the mass ratio of a central-driven ejector. The design parameters are the primary nozzle area and distance ratios, diffuser exit-area ratio and mixing-tube length ratio. The experimental setup was an open-loop continuous circulation system which has a movable nozzle ejector, an electric motor-pump, a water tank, a control panel and high-speed camera unit. We calculated the mass ratio using the measured primary and suction-flow rates with the experimental parameter of primary water-flow rate or pressure. The results showed that the mass ratio increased with the primary nozzle distance ratio and mixing tube length ratio, while the mass ratio decreased with the primary nozzle-area ratio and diffuser exit-area ratio.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.5
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• pp.439-445
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• 2012

Only the sand carriers fitted with hopper doors can remove their hatch covers in current regulations. However, there is no sand carriers fitted with hopper doors in korea. Through the analysis of accidents, inspection of equipment installed on ships, and evaluation of stability and seakeeping performance concerning the sand carriers, it is expected that the current exemption requirement is modified for hatch covers for sand carriers. As the result, this paper proposed the removal of hatch covers and be fitted by tarpaulin instead to protect water ingress into the holds. This can be done by making the holds smaller designed to be filled full until the top of the hold without exceeding loadline. Also, the bilge pumps should have the sufficient capacity of pumping water out in the early stage of sand-water mixture to wetted condition in approximately 1 hour and be operationally ready in every voyage conditions.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.6
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• pp.37-47
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• 2001

Due to the friction characteristics of pump, cylinder packing and passenger car, in the elevator actuated with hydraulic inverter-fed systems, there exist dead zones, which cannot be controlled by a PID controller. To overcome the drawbacks, in this paper, we propose a new hybrid control scheme, which switches the modes between a sliding mode controller and a PID controller. The proposed hybrid control scheme achieves an improved control performance by using both controllers. We first propose a design method of sliding mode controller for a hydraulic elevator system controlled by inverters, then fellowed by a design method of a hybrid sliding mode control scheme is proposed. The effectiveness of the proposed control scheme are shown by simulation results, which the proposed hybrid control method yields better control performance then the PID controlled scheme, not only in the zero-crossing speed region but also in the overall control region including steady-state region.