• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2187-2195
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• 2000

A water treatment system using membrane separation technology can provide stable effluent quality and its maintenance is relatively easy comparing to the conventional water treatment system. In addition, the membrane filtration system is very compact such that it can replace existing water treatment processes of coagulation/sedimentation/filtration by only one process. However, a major problem associated with membrane filtration is flux decline with operating time due to concentration polarization and fouling, so a systematic study on evaluation of long-term filtration performance is necessary. A membrane filtration system using tubular type ultrafiltration membranes with MWCO of 30.000 Da was constructed for this study and it had been operated in a feed-and-discontinuous bleed mode. Flux was stabilized after operation of 1.500 hours and maintaining above 25 LMH until 4.000 hours. Contaminants causing SS and turbidity were almost completely removed while the $UV_{260}$ and DOC removals were 55% and 49%, respectively. A simple mass balance equation was developed to predict maximum concentrations of SS, turbidity, $UV_{260}$ and DOC in a operation cycle. For SS and turbidity the measured max, concentrations in each cycle agree well with the predicted values while the measured max, concentrations of $UV_{260}$ and DOC were 59% and 37% of the predicted values, respectively.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.278-281
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• 2009

KSTAR(Korea Superconducting Tokamak Advanced Research)는 고성능 플라즈마 연구를 위한 대형 연구실험 장치이다. 이러한 거대 장치에는 많은 시스템이 분산되어 연결되어 있으며 그 구조 역시 매우 복잡하여 시스템간의 인터페이스에 많은 제약과 어려움이 따른다. 이러한 복잡하고 다양한 시스템을 통합하고 여기서 발생하는 여러 종류의 데이터를 획득하기 위해서 KSTAR는 EPICS(Experimental Physics and Industrial Control System)라는 오픈소스 기반의 분산 제어용 미들웨어를 구축하였고 이를 기반으로 KSTAR 통합 제어 시스템을 개발 하였다. 2008년 KSTAR 최초 플라즈마 실험 기간 동안의 운전을 통해 EPICS 미들웨어와 EPICS channel archiver를 이용하여 다양한 24시간 연속 운전데이터를 안정적으로 저장하고 추출할 수 있음을 확인하였다. 논문에서는 시스템의 구축 방법 및 운전결과에 대해 기술하고자 한다.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.187-192
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• 2018

This thesis is about the study of inverter terminal boxes in a explosion proof type exhaust fan that can control wind volume and operating time. In Korea, there is no ventilator to adjust the amount of wind and operating time when working in poor conditions. The purpose of the project is to create a explosion terminal box that can control the operating time and wind speed of a suitable explosion ventilator in hazardous environments. The two explosion-proof switches allow the operation time to be driven 1 hour, 3 hours and continuous time, and the speed of the induction motor rotation was set in 3 stages at 2000 rpm, 2600 rpm and 3000 rpm to control the volume. The tested motor used a half-horsepower barrier three-phase induction motor and a full-bridge inverter to set the desired flow rate and operating time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2393-2400
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• 2013

This research presents an experimental study of heat exchange rate of U, W, 2U and coil type ground heat exchangers (GHEs) measured by thermal performance tests (TPTs). The four types of GHEs were installed in a partially saturated dredged soil deposit of Incheon International Airport area. Thermal response tests (TRTs) were conducted for U, W and 2U type GHEs to deduce the ground thermal conductivity. Besides, TPTs were also conducted for U, W, 2U and coil type GHEs to evaluate heat exchanger rates under 100-hr continuous and 8-hr intermittent operation conditions for five days. Coil shaped GHE showed about twice higher thermal performance than the others GHEs. Furthermore, intermittent operation condition showed 30~40% higher heat exchange rates than continuous operation condition.

• Membrane Journal
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• v.26 no.6
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• pp.470-479
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• 2016

In the advanced treatment of sewage using the submerged membrane-coupled sequencing batch reactor (SMSBR) with media, the effect of media on the filtration performance and removal efficiency were investigated. Dosages of the media in the SMSBR were 10% based on working volume of reactor. As a control system, SMSBR without media and PAC, SMSBR with PAC (10 g/L) only, and SMSBR with media and PAC were also operated. The experimental results showed that there was no big difference observed in the removal efficiencies of COD, T-N, and T-P irrespective of the dosages of the media and PAC. But transmembrane pressure (TMP) of SMSBR with media increased slowly during the operation time, while that of SMSBR without media increased rapidly. Using SMSBR with media, it was possible to operate without the membrane cleaning during the 91 days. Using SMSBR with media only, after 80 days the average removal efficiencies of COD, T-N, and T-P were 95.0, 69.3%, and 51.4%, respectively.

• KSBB Journal
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• v.18 no.2
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• pp.111-116
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• 2003

Hydrogen producing acidogenic microorganisms were self-immobilized using organic-inorganic hybrid polymer within 5 minutes. During the continuous tratment of synthetic wastewater at a hydraulic retention time of 20 hours, at 37$^{\circ}C$, pH 5.0, the self-immobillized granules were maintained in a stirred tank reactor. The black colored granules gradually became milky. Image analysis showed that the mean diameter of the milky colored granules ranged from 1.5 to 20. mm. The maximum bio-gas procuction rate was 380 ml/L/hy and the concentration of H$_2$was around 50%, while no methane was detected. Granular ECP was extracted and its content was measured to elucidate the role of the organic-inorganic hybrid polymer. Further increases of granule concentration are expected to increase the hydrogen production rate.

• Membrane Journal
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• v.21 no.3
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• pp.263-269
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• 2011

In the operation of submerged membrane-coupled sequencing batch reactor, the effect of filling step on the removal efficiency and filtration performance were investigated. Two sets of operation modes, the filling step located in the beginning of aerobic step (Mode-1) and the beginning of anoxic step (Mode-2), during 89 days were conducted. There was no wide difference in the COD removal and filtration performance between two sets of operation modes. But in the removal efficiency of nutrients (total nitrogen and total phosphorous), Mode-2 was more effective than Mode-1. In the case of Mode-2, average removal efficiencies of COD, total nitrogen, and total phosphorous were 99.1, 73.3, and 77.3%, respectively.

• Journal of the Korean GEO-environmental Society
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• v.10 no.1
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• pp.43-48
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• 2009

This study was performed to investigate the characteristics of nutrient removal by Sequencing Batch Reactor (SBR) system, which could achieve high removal efficiencies of nitrogen and phosphorus and make it possible convenient management and operation. In this study, dissolved oxygen (DO), chemical oxygen demand (COD), nitrogen, and phosphorus in SBR system were examined by variation of anoxic-oxic phase repetition in order to optimize an operational method. The 1~4 times of anoxic-oxic phases (Run 1~4) were repeated during 1 cycle operation period. As the repetition frequency increased, it was more difficult to maintain DO condition enough for denitrification. The SBR system showed high COD removal efficiency more than 91% regardless of operational condition. About 68% of nitrogen removal rate was obtained in conditions of 2 or 3 times repetition of anoxic phases, in which NOx-N among discharged total nitrogen account for more than 99%. Approximately 40% of phosphorus was eliminated in the conditions of 1~3 times of anoxic phase repetition.

• Journal of the Korean GEO-environmental Society
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• v.14 no.4
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• pp.15-27
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• 2013

In order to plan out the Daegu G membrane filtration water treatment plant, water quantity, water quality and process stability were evaluated using the field pilot-scale tests, during the six months of continuous operation, including low water temperature period. The field model experiments, which were carried out according to the Installation Criteria of Ministry of Environment, consisted of two series : series 1 - water quality verification, and series 2 - membrane process evaluation. The process water quality met all drinking water standards with less than 0.03 NTU. Moreover, process operation showed a stable membrane pressure with 99% of recovery ratio. This shows that the tests were properly designed in terms of the influence of water loading and temperature. In conclusion, the purpose of this study is to establish core technology for advanced drinking water treatment, through on-going accumulation of engineering and construction know-how.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.296-302
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• 2019

In this study, a basic durability assessment was performed by selecting the main part of a trial product of a shale shaker, which is one of components for a mud circular system. For a preliminary durability assessment, it was assumed that the lifetime of the bearing for the vibrator motor and the stiffness of the support spring are affected by the vibration when the motor operates continuously. In the case of the motor, the initial p-p level was 0.72 g, but after 100 hours of operation, the p-p level was rapidly increased to 1.26 g. Bearing defects could be estimated through ball defect frequency analysis. In the case of the spring, the stiffness of the spring was reduced by approximately 3.78% at the end of 2,000 hours of the fatigue-durability test by applying excitation conditions to shale shaker body. In the future, we will analyze the influence of the particle removal efficiency of the shale shaker.