Mokpo, South Korea

Mokpo Maritime University

www.mmu.ac.kr
Mokpo, South Korea

Mokpo National Maritime University is a national university located in Mokpo, South Korea. Wikipedia.

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Disclosed herein are an apparatus and method for diagnosing the state of a power cable and measuring the remaining life thereof using VLF TD measurement data, and for determining a replacement time of a power cable using a 3D matrix exhibiting reproducibility of diagnosis of the state of the power cable. The apparatus and method for diagnosing the state of a power cable and measuring the remaining life thereof according to the present invention includes a Weibull modeling unit, a distance limiting unit, a data type classifying unit, a quantity representing unit, a normalization unit, a 3D constructing unit, a risk level calculating unit, and a remaining life measuring unit.


Choi H.-J.,Mokpo Maritime University
International Journal of Multimedia and Ubiquitous Engineering | Year: 2013

A CGH (Computer-Generated Hologram) is produced by calculating the interference pattern between the object wave and the reference wave. Thus it has been developed to get some ideal characteristics of CGH that are not possible in reality or to test the characteristics of a hologram. To generate a CGH with the hologram resolution of (M×N) for a 3D object having K light source, basically (N×N×K) calculational iterations are necessary. This paper proposes an algorithm that increases the speed of generating a digital hologram using a depth different temporal filtering (DDTF) of a depth video sequence. The proposed algorithm is a technique that performs CGH operation with only calculation the different depth values between the depth video frames. The experimental results showed that the proposed algorithm increased operation speed by 65% over the technique using the conventional CGH equation. & 2013 SERSC.


Lee S.-R.,Mokpo Maritime University
Lecture Notes in Electrical Engineering | Year: 2013

The possibility of implementing the randomly distributed residual dispersion per span (RDPS) in optical links with optical phase conjugator (OPC) for 960 Gbps WDM transmissions is studied and discussed. It is confirmed that RDPS of each fiber spans should be randomly selected to ensure that the deviation of the accumulated dispersion between two transmission sections with respect to OPC was set to be small, for example, RDPS of each fiber spans are randomly selected to ensure that the accumulated dispersion at each transmission sections are to -10~20 ps/nm for optical link with net residual dispersion (NRD) of 10 ps/nm. It is also confirmed that the best NRD in optical link with the randomly distributed RDPS is ±10 ps/nm rather than 0 ps/nm. Consequently, the randomly distributed RDPS is possible by applying the best NRD into optical link specified with the optimal combination condition of random RDPS. © 2013 Springer Science+Business Media Dordrecht.


Kim Y.-H.,Mokpo Maritime University | Lee J.-H.,Kongju National University
IEEE Transactions on Broadcasting | Year: 2011

In orthogonal frequency-division multiplexing (OFDM) systems, carrier and sampling frequency offsets (CFO and SFO, respectively) can destroy the orthogonality of the subcarriers and degrade the system performance. In this paper, we propose a new joint CFO and SFO maximum-likelihood (ML) estimation scheme extending Moose's CFO estimation scheme using two long training symbols in the frequency-domain (FD). In particular, we derive FD Cramér-Rao bounds (CRBs) for the mean square errors (MSEs) of the CFO and SFO estimation. Simulation results show that the proposed ML scheme exhibits better performance than the other existing methods. © 2011 IEEE.


The urea-SCR catalyst system has the advantages of high NOx conversion efficiency and a wide range of operating conditions. The key factors for successful implementation of urea-SCR technology are good mixing of urea (ammonia) and gas to reduce ammonia slip. Urea mixer components are required to facilitate evaporation and mixing, because it is difficult to evaporate urea in the liquid state; the distance to the mixer is the most critical factor affecting mixer performance. In this study, to determine the optimal distance from the injector to the mixer for urea injection, we used laser diagnostics and a high speed camera to analyze the spray characteristics of a urea injector and to determine the distribution of urea solution droplets in a transparent manifold. The spray angle with a certain value (α) was measured, the injection quantity was about 9.4208 g/s, the SMD was approximately 65 μm, and then the position Bd was the optimal location for installation of mixer. In addition, we calculated the droplet uniformity index (DUI) from the acquired images using digital image processing to clarify the distribution of the sprayed droplets. Analysis of the quantitative characteristics and spatial distribution of the droplets revealed that addition of mixers resulted in more uniform distribution of the urea solution in the exhaust pipe and improved the performance of the urea-SCR catalyst system. A grid-channel plate-type mixer was optimal for maintaining a high the DUI which increased 32% than the case without a mixer, and the NOx conversion efficiency which was 85-90%. © 2013 Elsevier Ltd. All rights reserved.


Kim S.-H.,Mokpo Maritime University | Das M.P.,Australian National University
Modern Physics Letters B | Year: 2012

We developed a new method of an earthquake-resistant design to support conventional aseismic system using acoustic metamaterials. The device is an attenuator of a seismic wave that reduces the amplitude of the wave exponentially. Constructing a cylindrical shell-type waveguide composed of many Helmholtz resonators that creates a stop-band for the seismic frequency range, we convert the seismic wave into an attenuated one without touching the building that we want to protect. It is a mechanical way to convert the seismic energy into sound and heat. © 2012 World Scientific Publishing Company.


Patent
Mokpo Maritime University | Date: 2012-11-29

Disclosed are an earthquake-proof barrier for protecting a building against an earthquake, and more particularly, an earthquake-proof barrier using buried resonant cylinders capable of weakening seismic waves outside a building, instead of installing an earthquake-proof apparatus in a building. According to the earthquake-proof barrier using the buried resonant cylinders, buildings are not independently protected, but one district beyond the earthquake-proof barrier is protected. Thereby, magnitude of an earthquake can be reduced to a desired level without altering the building.


Patent
Mokpo Maritime University | Date: 2015-03-26

Disclosed is a mobile robot for detecting and repairing damages of a hull, including: a mobile robot unit which includes at least one frame to which motor-driven drive wheels are installed, frame connectors which flexibly connect the frames with each other, and at least one robot electromagnet and adsorption module mounted on each of the frames, and is configured to be attached to the hull through the robot electromagnet so as to move or stop on a surface of the hull by the drive wheels; a stage unit which includes a rechargeable battery mounted therein to supply power to the mobile robot unit, and a docking module provided to dock with or separate from the mobile robot unit; and a connection line configured to be wound or unwound while receiving tension controlled by the stage unit, and electrically connected between the mobile robot unit and the stage unit.


Patent
KOREAN Electrical POWER CORPORATION and Mokpo Maritime University | Date: 2014-08-27

Disclosed herein are an apparatus and method for diagnosing the state of a power cable and measuring the remaining life thereof using VLF TD measurement data, and for determining a replacement time of a power cable using a 3D matrix exhibiting reproducibility of diagnosis of the state of the power cable. The apparatus and method for diagnosing the state of a power cable and measuring the remaining life thereof according to the present invention includes a Weibull modeling unit, a distance limiting unit, a data type classifying unit, a quantity representing unit, a normalization unit, a 3D constructing unit, a risk level calculating unit, and a remaining life measuring unit.


At least one resonance chamber is disposed around an air passage channel passing through a window or a wall, and the air passage channel and the resonance chamber are separated from each other by a porous sound absorber. When sound and air pass through the air passage channel, the sound is absorbed and cut off by the resonance chambers, and the air passes through the air passage type channel. As a result, an air passage type soundproof window or wall through which the air passes and by which the sound is cut off can be manufactured, and a water passage type soundproof window or wall through which water passes and by which the sound is cut off in the same principle can be manufactured.

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