Lim Y.S.,Pukyong National University |
Lim Y.S.,DaeYang Co. |
Park K.-H.,Korea Institute of Ceramic Engineering And Technology |
Tak J.Y.,Korea Institute of Ceramic Engineering And Technology |
And 7 more authors.
Journal of Applied Physics | Year: 2016
Among many kinds of thermoelectric materials, CoSb3 has received exceptional attention for automotive waste heat recovery. Its cage structure provides an ideal framework for the realization of phonon-glass electron-crystal strategy, and there have been numerous reports on the enhanced thermoelectric performance through the independent control of the thermal and electrical conductivity by introducing fillers into its cage sites. Herein, we report colligative thermoelectric transport properties in n-type CoSb3 from the viewpoint of "guest electrons in a host lattice." Both the Seebeck coefficient and the charge transport properties are fundamentally determined by the concentration of the guest electrons, which are mostly donated by the fillers, in the conduction band of the host CoSb3. Comparing this observation to our previous results, colligative relations for both the Seebeck coefficient and the mobility were deduced as functions of the carrier concentration, and thermoelectric transport constants were defined to predict the power factor in filled CoSb3. This discovery not only increases the degree of freedom for choosing a filler but also provides the predictability of power factor in designing and engineering the n-type filled CoSb3 materials. © 2016 AIP Publishing LLC.
Lee D.J.,KAIST |
Jang J.J.,KAIST |
Park H.S.,KAIST |
Kim Y.C.,Agency for Defense Development |
And 3 more authors.
Ceramics International | Year: 2012
Biomorphic SiC composites were fabricated from wood, including high-density compressed cedar, high-density fiberboard (HDF) and low-density paulownia followed by the fabrication of a preform and liquid silicon infiltration (LSI) process. The degree of molten silicon infiltration was strongly dependent on the cell wall thickness and pore size of the carbon preform. The mechanical properties of the biomorphic SiC composites were characterized by compressive tests at room temperature, 1000 °C and 1200 °C, and the relationship between the mechanical properties and the microstructural characteristics was analyzed. The compressive strength of the biomorphic composites was found to be strongly dependent on their bulk density and decreased as the test temperature increased to 1200 °C. Strength reduction in the biomorphic SiC composites occurred due to the deformation of the remaining Si at elevated temperatures under ambient atmospheric conditions. © 2011 Elsevier Ltd and Techna Group S.r.l.
Lee D.,KAIST |
Kim Y.C.,Agency for Defense Development |
Adeel Umer M.,KAIST |
Lim K.H.,DaeYang Co. |
And 2 more authors.
Ceramics International | Year: 2013
Biomorphic SiC composites were fabricated by infiltration of liquid Si into a preform fabricated from medium-density fiberboard (MDF). The phase compositions, microstructures, oxidation behaviors, and ablation properties of the composites were investigated. The composites were oxidized at elevated temperatures (up to 1450° C) in air to study their oxidation behavior. Pores and cracks initially formed from the oxidation of residual carbon, followed by melting of residual Si. The ablation resistance of a composite was gauged using an oxy-acetylene torch. The formation of a SiO2 layer by the oxy-acetylene flame improved the ablation resistance because molten SiO 2 spread over the ablated surface and partially sealed the pores, thus acting as an effective barrier against the inward diffusion of oxygen. © 2013 Elsevier Ltd and Techna Group S.r.l.
Ham Y.-S.,DaeYang Co. |
Kim J.-T.,e Design Center |
Kwak S.-Y.,e Design Center |
Choi J.-K.,e Design Center |
Yoon W.-Y.,Korea University
China Foundry | Year: 2010
Critical cooling rate to avoid carbide precipitation during quenching of austenitic manganese steel was investigated by means of optical microscopy, image analyzer and numerical analysis. An efficient heat treatment analysis program including temperature-dependent material properties was developed for the prediction of cooling rate and probability of carbide precipitation during quenching by finite difference method. Time-dependent heat transfer coefficient was adopted to achieve more precise results. Area ratio of carbide precipitation was measured by image analyzer to determine the critical point of carbide precipitation, Temperature-dependent critical cooling rate at that point was calculated by the developed numerical program. Finally, the probability of carbide precipitation on the whole area of specimen can be predicted by the proposed numerical program and the numerical result of a specimen was compared with the experimental result.
Li J.H.,Korea Institute of Robot and Convergence KIRO |
Kim J.T.,Korea Institute of Robot and Convergence KIRO |
Lee M.J.,Korea Institute of Robot and Convergence KIRO |
Lee W.S.,Korea Institute of Robot and Convergence KIRO |
And 4 more authors.
2014 Oceans - St. John's, OCEANS 2014 | Year: 2015
ROV trencher is a kind of heavy-duty work class ROV with high pressure water jetting tools cutting the sea floor and burying the cable. This ROV is mostly used for PLIB (post lay inspection and burial) operation. For a ROV trencher, usually there is a pair of jetting legs mounted at the bottom and stowed in a horizontal position in its rest mode. While burying cable in the sea floor, they are folded out by hydraulic cylinders, and cut the sea floor by jetting high pressure water and simultaneously bury the post laid cable. In this working process, there are various external forces acting on the vehicle. From control point of view, obviously there are some of optimal issues that of how we should construct the thrust system so that can minimize or maximize kinds of optimal criteria such as minimizing power consumption, or maximizing some of burial performances (burial depth, progress rate etc.). All of these conceptual design considerations for effective thrust system will be considered in this paper. © 2014 IEEE.
Lee P.M.,Korea Ocean Research and Development Institute |
Lee C.M.,Korea Ocean Research and Development Institute |
Kim K.,Korea Ocean Research and Development Institute |
Choi H.T.,Korea Ocean Research and Development Institute |
And 15 more authors.
Program Book - OCEANS 2012 MTS/IEEE Yeosu: The Living Ocean and Coast - Diversity of Resources and Sustainable Activities | Year: 2012
This paper presents an unmanned underwater vehicle (UUV) with high maneuverability to be controlled in strong tidal currents. A radio buoy is connected to the UUV with an intermediate cable, and a wireless RF modem is installed to communicate with a support vessel. This paper presents the design and development of the UUV and the buoy systems. The vehicle equips with two main thrusters and four vertical/ horizontal tunnel thrusters in the middle of the vehicle. This paper discusses the hydrodynamic characteristics of the multiple thrusters, and strategies to maneuver the UUV with multiple thruster. Finally this paper presents effectiveness of the UUV with the buoy in conducting a simulated object installation. © 2012 IEEE.
Hwang S.S.,Pusan National University |
Kim S.C.,Pusan National University |
Lee C.D.,DaeYang Co.
ICCET 2010 - 2010 International Conference on Computer Engineering and Technology, Proceedings | Year: 2010
In this paper, we study real time acoustic echo cancellation technique based on NLMS (normalized least mean square) method and propose a method to improve conversation quality by the enhancement of acoustic echo cancellation technique performance during DT (double talk) section. In the environment that echo path changes slowly, proposed method stores past converged adaptive filter coefficients periodically and uses them when the DT section is started, instead of using complex DTD (double talk detector) algorithm to obtain the precise starting point of DT. Proposed method gives just small additional calculation and shows performance enhancement in terms of the remained echo during DT section. © 2010 IEEE.
Kwon H.-J.,Korea Research Institute of Standards and Science |
Choi W.-C.,DaeYang Co.
Microsystem Technologies | Year: 2010
This paper describes the design and fabrication of a flexible three-axial tactile sensor array using advanced polyimide micromachining technologies. The tactile sensor array is comprised of sixteen micro force sensors and it measures 13 mm × 18 mm. Each micro force sensor has a square membrane and four strain gauges, and its force capacity is 0.6 N in the three-axial directions. The optimal positions of the strain gauges are determined by the strain distribution obtained form finite element analysis (FEA). The normal and shear forces are detected by combining responses from four thin-film metal strain gauges embedded in a polyimide membrane. In order to acquire force signals from individual micro force sensors, we fabricated a PCB based on a multiplexer, operational amplifier and microprocessor with CAN network function. The sensor array is tested from the evaluation system with a three-component load cell. The developed sensor array can be applied in robots' fingertips, as well as to other electronic applications with three-axial force measurement and flexibility keyword requirements. © 2010 Springer-Verlag.
DaeYang Co. | Date: 2013-10-04
Disclosed is an electronic bucket-type precipitation meter including: an inclined bucket which extends at an angle from one edge to the center so as to collect rainwater; a measurement bucket which extends downward so that the rainwater is collected at the center of the inclined bucket, wherein a measurement unit is installed on a side surface thereof so as to measure the collected rainwater; a covering part in which the upper covering part is formed at the upper part thereof and has an inclined contact surface having the same incline as the inclined bucket, and in which the lower covering part is formed at the lower part thereof so as to block the bottom surface of the measurement bucket; and a lifting and lowering driving unit which lifts and lowers the cover part.
DaeYang Co. | Date: 2016-04-05
Unmanned submersibles, namely, submarines for military, scientific or geological exploration purposes.