유니몰프 압전소자를 이용한 발전 판넬의 출력특성에 관한 연구

김용혁,Kim, Yong-Hyuk 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.3

The ability for energy harvesting via the piezoelectric effect was studied for a unimorph element such as piezo buzzer. A simple equivalent circuit was proposed to predict the energy generated based on the internal stress. Unimorphs with a metal-cavity were used as a driving device of the generation panel. Both the AC open voltage and DC output voltage as a function of pressure period and number of element were measured. For the unimorph generation circuit, DC output voltage varies with pressure period, reaching a maximum value at $470{\mu}F$. The maximum output voltage a according to load resistance was measured at $1M{\Omega}$. Data analysis of the DC output voltage and time constant indicated that number of piezoelectric element of optimum was 60~80. It was found that piezoelectric unimorph has the possibility to be used as the driving element of the electric generation.

Al/Air 연료전지의 출력특성에 미치는 KOH 전해질과 H₂O₂ 감극제의 영향

김용혁,Kim, Yong-Hyuk 대한전기학회 2015 전기학회논문지 P Vol.64 No.4

The effects of additive such as $H_2O_2$ in KOH electrolyte solution for the Aluminum/Air fuel cell were investigated with regard to electric power characteristics. The power generated by a Al/Air fuel cell was controlled by the KOH electrolyte solution and $H_2O_2$ depolarizer. Higher cell power was achieved when higher KOH electrolyte concentration and higher $H_2O_2$ depolarizer amount. The maximum power was increased by the increase amount $H_2O_2$ depolarizer, it was found that $H_2O_2$ depolarizer inhibits the generation of hydrogen and the polarization effect was reduced as a result. Internal resistance analysis was employed to elucidate the maximum power variation. Higher internal resistance created internal potential differences that drive current dissipating energy. In order to improve the output characteristics of the Al/Air fuel cell, it is thought to be desirable to increase the KOH electrolyte concentration and increase the $H_2O_2$ addition amounts.

공기 매질에 의한 압전 세라믹스의 분극효과

김용혁,Kim, Yong-Hyuk 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.6

A new method for the poling of piezoelectric ceramics with an air insulation medium in stead of silicon oil is described. A similar variation of electromechanical coupling coefficient $K_t$, for an air medium is observed in comparison to that of the material poled by the conventional poling method using a silicon oil medium. Different poling parameters such as dielectric constant $\varepsilon^T$ and frequency deviation ${\Delta}f$ are studied as well as the influence on the aging effect. The required poling factors to achieve the optimal piezoelectric characteristics are electric field, 2 kV/mm, temperature $100^{\circ}C$, and poling time 30 Min. From this result electric field 3 kV/mm atmosphere airs there being will be able to use with the polarization insulation medium about the piezoelectric material, confirmed.

NaCl 전해질 농도 변화에 따른 다공질 탄소전극의 전기적 특성

김용혁,Kim, Yong-Hyuk 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.10

Porous carbon electrodes with wooden materials are manufactured by molding carbonized wood powder. Electrical properties of the interface for electrolyte and porous carbon electrode are investigated from viewpoint of NaCl electrolyte concentration, capacitance and complex impedance. Density of porous carbon materials is 0.47~0.61 g/$cm^3$. NaCl electrolytic absorptance of the porous carbon materials is 5~30%. As the electrolyte concentration increased, capacitance is increased and electric resistance is decrease with electric double layer effect of the interface. The electric current of the porous carbon electrode compared in the copper and the high density carbon electrode was improved on a large scale, due to a increase in surface area. The circuit current increased as the distance between of the porous carbon electrode and the zinc electrode decreased, due to increase in electric field. Experimental results indicated that the current properties of galvanic cell could be improved by using porous carbon electrode.

금속-공기전지의 Anode전극 반응에 관한 연구

김용혁,Kim, Yong-Hyuk 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.12

In this study, magnesium (Mg), zinc (Zn) and aluminium (Al) as anode electrode and the solution of NaCl dissolved with 2~20 wt% as electrolytes were used for the metal-air cell. The open circuit voltage, short circuit current and I-V characteristics upon different kinds of anode electrode and electrolyte concentration were investigated. The open circuit voltage, initially about 1.45 V, rises to 1.6 V during the first 10 minutes indicating the necessity of an induction time to activate the catalyst on the air cathode. The short circuit current increases with an increased concentration of NaCl, causes an increase in the conductivity of the electrolyte solution, but the open circuit voltage did not under undergo influence of electrolyte. From NaCl 20 wt% electrolyte, the maximum output power of the magnesium electrode materials was measured with 177mW. It is found that the power characteristics of metal-air cell could be improved by using magnesium electrode materials in the NaCl electrolyte.

산업교육훈련에 관한 구성원의 지각실태연구

김용혁(Yong-Hyuk Kim) 한국경영교육학회 1997 경영교육연구 Vol.14 No.-

입력파형에 따른 PZT 바이몰프 진동자의 출력특성

김용혁(Yong-Hyuk Kim),추순남(Soon -Nam Chu) 대한전기학회 2013 전기학회논문지 P Vol.62 No.1

The aim of this study is to research maximum harvesting energy by the optimal input wave condition. The voltage characteristics of the PZT bimorph were investigated in terms of the sine wave, triangle wave and square wave according to frequency range 0~70Hz. It was found that the square wave compared with a triangular wave or square wave was showed the higher output energy. PZT bimorph was mechanically vibrated by solenoid coil experiments, which revealed two voltage peak mode according to frequency. Maximum voltage at second vibration frequency 28Hz demonstrated that the generated DC voltage was proportional to the tip displacement of the bimorph and the phase difference between the input frequency and bimorph vibration frequency was 90 degree. It was expected that optimized design to harvest a much higher energy level from lower frequency vibrations.

Al/Air 연료전지의 출력특성에 미치는 KOH 전해질과 H₂O₂ 감극제의 영향

김용혁(Yong-Hyuk Kim) 대한전기학회 2015 전기학회논문지 P Vol.64 No.4

The effects of additive such as H₂O₂ in KOH electrolyte solution for the Aluminum/Air fuel cell were investigated with regard to electric power characteristics. The power generated by a Al/Air fuel cell was controlled by the KOH electrolyte solution and H₂O₂ depolarizer. Higher cell power was achieved when higher KOH electrolyte concentration and higher H₂O₂ depolarizer amount. The maximum power was increased by the increase amount H₂O₂ depolarizer, it was found that H₂O₂depolarizer inhibits the generation of hydrogen and the polarization effect was reduced as a result. Internal resistance analysis was employed to elucidate the maximum power variation. Higher internal resistance created internal potential differences that drive current dissipating energy. In order to improve the output characteristics of the Al/Air fuel cell, it is thought to be desirable to increase the KOH electrolyte concentration and increase the H₂O₂ addition amounts.

금속연료전지에서 이온교환막이 전기전도에 미치는 영향

김용혁(Yong-Hyuk Kim) 대한전기학회 2010 전기학회논문지 Vol.59 No.12

In this study, The cation exchange membrane and the anion exchange membrane affect in electrical conduction of metal fuel cell was investigated. Magnesium material as anode electrode and the NaCl solution dissolved with 5~15wt% as electrolyte were used for the metal fuel cell. It was found that magnesium slag where flows toward the air electrode was suppressed by using ion exchange membrane. The open circuit voltage variation during discharge has very flat pattern by using ion exchange membrane, but the case which is not the exchange membrane, the open circuit voltage increased according to time. When using the anion exchange membrane, the electric current was higher case of the cation exchange membrane, as a result of higher equivalent conductivity in anion Cl-. The cation exchange membrane was observed with the fact that the output power is excellent in compared with anion exchange membrane.

Cantilever형 바이몰프 압전소자의 출력특성에 관한 연구

김용혁(Yong-Hyuk Kim) 대한전기학회 2010 전기학회논문지 Vol.59 No.3

Using piezoelectric elements to harvest energy from ambient vibrations has been of great interest over the past few years. Due to the relatively low power output of piezoelectric materials, there are many study to improve the energy harvesting efficiencies. This paper is study the efficiencies of the output energy considering the cantilever piezoelectric bimorph using aluminum vibration beam. when the length of vibration beam and the piezoelectric body becomes same and the maximum output power comes out. DC voltage was increased as the beam thickness and vibration frequency was increased. The vibration beam was able to achieve very large energy value.