Kang S.,Korea Institute of Machinery and Materials
Energy | Year: 2015
Water management is one of the challenging issues for low-temperature PEMFCs (proton exchange membrane fuel cells). When liquid water is formed at the GDL (gas diffusion layer), the pathway of reactant gas can be blocked, which inhibits the electrochemical reaction of PEMFC. Thus, liquid water transport through GDL is a critical factor determining the performance of a PEMFC. In present study, quasi-three dimensional dynamic modeling of PEMFC with consideration of two-phase water transport through GDL is developed. To investigate the distributions of PEMFC characteristics, including current density, species mole fraction, and membrane hydration, the PEMFC was discretized into twenty control volumes along the anode channel. To resolve the mass and energy conservation, the PEMFC is discretized into eleven and fifteen control volumes in the perpendicular direction, respectively. The dynamic variation of PEMFC characteristics of cell voltage, overvoltage of activation and ohmic, liquid water saturation through a GDL, and oxygen concentration were captured during transient behavior. © 2015 Elsevier Ltd.
Korea Institute of Machinery and Materials | Date: 2015-10-28
A resonance generating apparatus for testing blade fatigue with reduced side load includes a mounting portion comprising a saddle including a groove corresponding to an external surface of a blade, and an assembling portion positioned on an external side of the saddle and joined by tightening members so that the saddle presses against the blade, a resonance generator including an actuator to generate a linear movement, a coupler(s) to maintain phase of a blade motion the same as an actuator rod, and a linear guide to guide a direction of linear reciprocating motion of an actuator body, and weights mounted on opposite faces of the actuator body to move in association therewith, and varied in a lengthwise direction of the blade so a center of gravity of moving masses of the actuator body in linear reciprocation and the additional weights is positioned on an axis of the actuator rod.
Korea Institute of Machinery and Materials | Date: 2015-04-03
A quantum dot stabilized by a halogen salt includes a compound of Group 13 and Group 15, a compound of Group 12 and Group 16 or a compound of Group 14 and Group 16. The quantum dot has a crystalline structure and at least a portion of a surface of the quantum dot is combined with a halogen salt. Thus, the quantum dot has a high stability in an air.
Korea Institute of Machinery and Materials | Date: 2015-01-22
A piezoelectric fiber composite and a magnetoelectric laminate composite including the same are disclosed. The piezoelectric fiber composite includes a first protective layer having a first electrode, a second protective layer having a second electrode, and a piezoelectric fiber layer formed between the first and the second electrode and having piezoelectric fibers arranged in the longitudinal direction of the composite, wherein the piezoelectric fibers include a single-crystal piezoelectric material and are configured such that a <011> direction of the single crystal is identical to a thickness direction of the composite and a <001> direction of the single crystal is identical to a longitudinal direction of the composite, thus exhibiting superior piezoelectric strain properties and sensing properties. Also, the magnetoelectric laminate composite includes the piezoelectric fiber composite and a magnetostrictive layer including a magnetostrictive material such as nickel (Ni) or Metglas (FeBSi alloy), thus ensuring significantly improved magnetoelectric properties.
Korea Institute of Machinery and Materials | Date: 2015-05-11
A vehicle air purifying apparatus is provided. The vehicle air purifying apparatus includes: a charger configured to discharge positive (+) ions or negative () ions to charge particles included in harmful gas; a removable collecting electrode configured to have positive (+) or negative () polarity to allow the particles charged by the charger to be attached thereto; and a filter configured to filter harmful gas and have positive (+) or negative () polarity, and the filter is formed in a tubular shape having an empty space therein and the removable collecting electrode is inserted into the filter.