• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.472-478
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• 2019

A stable desalination method of the hardness substance such as $Ca^{2+}$ by controlling the total charge (TC) supplied to the membrane capacitive deionization (MCDI) cell was studied. The adsorption (1.5 V) and desorption (0.0 V) were repeated 30 times while varying the TC in the adsorption process. The concentration and pH of effluent, adsorption and desorption amounts, current densities and cell potentials were analyzed in the desalination process. The maximum allowable charge (MAC) of the carbon electrode used in MCDI cell was measured to be 46 C/g. As a result of operation at TC (40 C/g) below the MAC value, electrode reactions did not occur, resulted in the stable desalination characteristics for a long-term operation. When operating at TCs (50, 60 C/g) above the MAC value, however, the concentration and pH of effluent varied greatly. Also, the scale was formed on the electrode surface due to electrode reactions, and the electric resistance of the cell gradually increased. It was thus concluded that it is possible to remove stably the hardness substance without any electrode reactions by controlling the charge supplied to MCDI cell during the adsorption process.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.360-361
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• 2014

등명기 및 통신, 해상관측장비 등에 필요한 충분한 소비전력 확보와 축전지 장수명을 위한 목적이다. 태양광 발전 시스템에서 태양광은 자동차의 연료와 같다. 따라서 기존 육상 태양광 시스템에서 발전하는 성과와 해상 등부표 위 한정된 면적 공간에서 발전 가능성을 정확히 분석하기 위해 연료에 대한 고도의 지식과 미래 신뢰성을 확보하는 것이 필수적이다. 해상 해수면 등부표 위에 탑재되는 독립형 태양광발전 시스템의 성과를 예견하는 데에는 일사량의 변화가 가장 큰 불확실성을 나타낸다. 그 이유는 대기와 해상기후의 상태에 따라 태양광이 대기를 통과하면서 전달 산란 채광 흡수되는 작용이 다르고 불안정한 대기와 해상의 롤링과 피칭으로 수광(채광) 조건이 변화무쌍하기 때문이다. 등부표의 한정된 면적과 공간에서 전력공급을 할 수 있는 한계가 있다. 정보통신기술(ICT) 발달에 따른 소비전력 연동시스템 증가로 인해 절대적인 전력량 확보가 필요하다.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.208-209
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• 2016

본 논문에서는 가동물체형 AFPM 파력 발전기용 시뮬레이터 구현 및 실험을 수행하였다. 파력 발전기는 파도의 에너지를 이용하여 부이의 움직임에 따라 발전하는 방식이다. 기존의 소형 파력 발전 시스템의 경우 단순히 전파 정류하여 축전지에 충전하는 방식을 사용한다. 그러나 전파 정류기를 사용하는 경우 파도에 속도에 따른 최적의 발전량을 제어하지 못해 발전 효율이 떨어지는 단점이 있지만, 인버터를 사용하는 경우 속도에 따른 발전량을 순시 적으로 제어할 수 있어 발전 효율을 높일 수 있다. AFPM 파력 발전기의 제어를 위하여 전류제어기와 센서리스 알고리즘을 구성하였으며 구현된 제어기는 파력 발전 시뮬레이터 실험을 통하여 회전자 위치 추정 및 속도에 따른 제어 성능을 확인하였다.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.269-275
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• 2015

The adsorption characteristics of ions were evaluated for the nitrate-selective carbon electrode (NSCE) in accordance with power supply methods. The NSCE was fabricated by coating the surface of a carbon electrode with anion-exchange resin powders with high selectivity for the nitrate ion. Capacitive deionization (CDI) experiments were performed on a mixed solution of nitrate and chloride ion in constant voltage (CV) and constant current (CC) modes. The number of total adsorbed ions in CV mode was 15% greater than that in CC mode. The mole fraction of adsorbed nitrate ion showed the maximum 58%, though the mole fraction was 26% in the mixed solution. This indicates that the fabricated NSCE is highly effective for the selective adsorption of nitrate ions. The mole fraction of adsorbed nitrate was nearly constant value of 55-58% during the adsorption period in CC mode. In the case of CV mode, however, the values increased from the initial 30% to 58% at the end of adsorption. We confirmed that the current supplied to cell is important factor to determine the selective removal of nitrate.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.898-902
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• 2008

Prepared are three types of composite supercapacitor electrode, such as electroactive polyaniline(PAN), PAN/multi-walled carbon nanotube(CNT), and $CNT/PAN/RuO_2$. Cyclic voltammetry was performed to investigate the supercapacitive properties of these electrodes in an electrolyte solution of 1.0M $H_2SO_4$. The $CNT/PAN/RuO_2$ electrode showed the highest specific capacitance at all scan rates(e.g., 441 and $392F\;g^{-1}$ at 100 and $1,000mV\;s^{-1}$, respectively). In cycle performance, however, the PAN/CNT electrode demonstrated the best capacitance retention (66%) at $10^4th$ cycle.

• Journal of the Korean Electrochemical Society
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• v.17 no.1
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• pp.37-43
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• 2014

In this study, capacitive deionization (CDI) was introduced for desalination of mining water. Ion-exchange polymer coated carbon electrodes (IEE) were used in CDI to desalt mining water. The CDI performance using the IEE for desalination of mining water was carried out and then was compared with that using general carbon electrodes without ion-exchange polymer coating (GE). Moreover, to investigate the effect of the concentration of influent solutions on CDI performance, the CDI performance using the IEE for desalination of brackish water (NaCl 200 ppm) was also performed and analyzed. As a result, the higher salt removal efficiency, rate and the lower energy consumption in the CDI process using the IEE and mining water were obtained compared with those using the GE and mining water. It is mainly due to higher non-Faradaic current, low ohmic resistance of the influent, overlapping effect of electric double layers in micropore of the electrode. In addition, the CDI process using the IEE and brackish water shows much higher salt removal efficiency and lower salt removal rate than that using the IEE and mining water. This results from the lower concentration (i.e., higher ohmic resistance) and salt amount of the influent.

• Journal of Navigation and Port Research
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• v.35 no.8
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• pp.631-636
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• 2011

Stable power supply to a light mounted on a navigational buoy is indispensable factor because unstable power can lead to fatal marine accident. Despite the difference lies between onshore and offshore environment, as well as the power output characteristics, the PV(Photovoltaic) power generation system is designed by the independent onshore power generation system standards. Furthermore, the capacity of PV power generation system does not take into account the structural characteristics of the buoy in the sea. Therefore, the faulty design makes battery over-discharge owing to lack of the power generation and the battery can not supply stable power to the light. This paper introduces a design method for a power system of the PV powered buoy. The data has been acquired for 3 months period, which includes PV-generated electricity, power consumption and battery voltage from experimental buoy. Further, a power management features of the buoy has been analyzed based on the acquired data. From the analysis of the acquired data, it was evident that PV power generation system produces different electric power output depend on its installed environment - land and sea. Based on the analytical result, a design criterion has been proposed for the power system in the navigational buoy.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.791-794
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• 2010

This study presents channel design of a CDI stack to achieve high removal efficiency in a large scale by applying parallel flow structure with a concentrated stream. The flow pattern in the stack was simulated by COMSOL Multiphysics program. To prove the salt removal performance, a unit cell and 20 cell stacks were tested at a flow rate condition of 18 ml/min and 360 ml/min, respectively. The removal efficiencies of the unit cell and the 20 cell stacks were obtained as 70.8 % and 75.6 %, respectively, with 100 mg/L sodium chloride solution. During the operation of cell test, water pressures of unit cell and 20 cell pair stack maintained in the ranges of 1.1 psi and 1.3~1.5 psi, respectively. It was demonstrated that the parallel cell structure with two concentrated streams can be employed in a large scale CDI for salt removal.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.618-620
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• 2008

본 논문에서는 대기 오염 물질의 방출이 적고, 소음이 적은 환경 친화적인 Ni-MH전지를 독립형 태양광 가로등시스템에 적용하였으며 충방전제어기를 구성하여 출력특성을 고찰하였다. 출력특성을 고찰한 결과 충전 및 방전이 원활히 진행됨을 알 수 있었다. 그러나 충전시 정전압 충전방식을 사용하였고 태양 전지 출력측에 MPPT제어가 이루어 지지 않은 탓으로 태양전지 이용률이 떨어지며 화창한 날 태양전지의 등가 발전시간은 약 6시간에서 7시간 정도 나오지만 축전지는 오전 중에 충전이 완료되고 오후발전량은 모두 버리게 됨을 알 수 있었다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.113_114
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• 2009

우리나라 전기자동차의 잠재 전력수요는 최대부하 측면에서 분석해보면 2008년말 현재 우리나라 자동차 16,794,287대를 전력부하로 환산해보면 1,887,017MW로서 우리나라 발전용량(70,353MW)의 약27배로 나타난다. 다행히도 전기자동차는 비동시 부하이며 최대부하로 충전하지는 않으므로 동시에 그만한 최대전력수요가 필요한 것은 아니다. 그러므로 연간 공급가능한 전기에너지(GWh)를 밸리 필링(Vally Filling;여유 심야전력) 전력량으로 구해보면 약 50,151GWh/년이고, 전기자동차의 에너지 필요용량을 계산해보면 46,587GWh/년이 된다. 이 결과는 전기자동차용 에너지양이 기설 발전설비로 공급가능한 밸리 필링 전력량의 93%로서 전기자동차의 수요를 적당한 시간대로 유도하면 현재의 발전설비 용량으로도 전기자동차에 에너지 공급이 가능하다는 것을 의미한다. 그러나 수도권의 자동차가 45.9%를 차지하고 있어 향후 수도권의 전력공급을 위한 전력 수송의 병목현상인 북상조류의 문제는 심화될 위험이 있다. 하지만 전기자동차의 축전지를 계통에 연계하여 분산전원으로 운영한다면 계통의 피크전력과 예비전력, 주파수 조정 등에 이점을 가져올 수도 있을 것이다.