• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.21 no.6
• /
• pp.123-128
• /
• 2021

As the spread of DC power distribution systems increases, the occurrence of failures and fire accidents are also increasing. In particular, the ESS fire accident, which is a component of the smart grid, and the fire accident of the solar power system, which is a direct current system, are caused by problems in the electrical connection between system components as the supply of new and renewable energy rapidly increases and old facilities increase. An arc that can cause a direct fire by releasing the induced light and heat has been pointed out as one of the causes of fire. Therefore, the problem of such an arc defect is that it is impossible to block an arc accident in advance with the existing overcurrent circuit breaker and earth leakage circuit breaker. In this paper, we intend to develop a test equipment that satisfies international standardization and to develop a DC arc generator to protect against failure and fire caused by arcing.

• Journal of Convergence for Information Technology
• /
• v.8 no.6
• /
• pp.375-380
• /
• 2018

This paper proposes a classification method using the Convolutional Neural Network(CNN) which can obtain the type of trucks from the input image without the feature extraction step. To automatically classify vehicle images according to the type of truck cargo box, the top view images of the vehicle are used as input image and we design the structure of the CNN suitable for the input images. Learning images and correct output results is generated and the weights of neural network are obtained through the learning process. The actual image is input to the CNN and the output of the CNN is calculated. The classification performance is evaluated through comparison CNN output with actual vehicle types. Experimental results show that vehicle images could be classified with more than 90 percent accuracy according to the type of cargo box and this method can be used for pre-classification for inspecting loading defect.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.05a
• /
• pp.404-407
• /
• 2014

Delay Tolerant Network (DTN) is a networking architecture that is designed to solve network problem in unstable and stressed environments using the Store-Carry-Forward method. Different form general networks, DTN does not guarantee the end-to-end connectivity, it is hard for the exiting TCP/IP based protocols to normally work due to the characteristic such as large latency and unstable link connectivity. And the condition that send massage without the information of the destination occurs frequently. Thus, suitable routing protocols for DTN are required and being researched. In this paper, we propose a novel routing protocol for DTN utilizing epidemic and prediction based algorithm to prevent the defect of previously DTN routing protocols such as the absence of the holistic view of the network. Proposed algorithm predicted destination using the mobility information recorded in neighbor node's history and utilize epidemic based algorithm when occurred condition without destination's information. This algorithm is enhanced in terms of delivery ratio, decreases latency and overhead in sparse network such as DTN.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.7
• /
• pp.347-352
• /
• 2019

This study focused on improving the cast quality of small-sized induction motor rotors during the die casting process. A new rotor core cast model was proposed based on previous research results and parametric studies. Numerical analyses using 3-dimensional half models were performed to evaluate the filling patterns of aluminum molten metals into a mold and on-site experiment performed to verify the newly proposed cast model. The following were obtained from numerical filling analyses and experimental results. First, molten metals started to fill the lower end ring, then moved on to fill the core slot and upper end ring and finally stopped to fill at the rotor core slot. Second, significant circulation of molten metals was not observed on the lower end ring, resulting in fewer defects at the section of the lower end ring from the experimental results. Third, the new shape of a rotor core cast was effective in producing rotors with sound cast quality, and reducing the end ring cast defect area by approximately 70 %.

• The Journal of the Acoustical Society of Korea
• /
• v.38 no.3
• /
• pp.334-339
• /
• 2019

In this study, the vibration test method to nondestructively evaluate the possibility of vehicle BSR (Buzz, Squeak, Rattle) noise generation in spot-welded structures was proposed. The weld quality was predicted by analyzing the local vibration transmission characteristics for the beam-shaped structure attached to testing spots. The bending stiffness was evaluated from the identified vibration properties. From the change in the stiffness, the weld quality was evaluated. For verification of the proposed method, the welded specimens were fabricated with partial changes in welding parameters. The local vibration transfers were measured. The frequency bands affected by the weld quality was identified. The capability of evaluating the welding parameters including defect position and quality variations was investigated. The proposed method enables fast quality evaluation to minimize the possibility of BSR noise generation in the manufactured vehicle.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2019.05a
• /
• pp.220-222
• /
• 2019

Korean automobile industry has been slow down since 2016. The most fundamental solution for solving this problem is to develop competitive parts. There are two important factors for developing competitive parts. The most important is product design technology, and the second most important is production technology. Production technology is important because it requires lowering the production cost except for the material cost and continuously maintaining the quality. In this paper, an intelligent smart inspection system is proposed and designed to inspect automobile parts of company C. At present, the basic and detailed design of this system has been completed and it is in the development progress stage. If the system is successfully developed, it is expected that the quality inspection stage of company C will be automated and the defect rate will be reduced.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.36 no.4
• /
• pp.71-81
• /
• 2020

The purpose of this study is to propose the planning methods for pollution prevention in the initial design stage by identifying the pollution phenomena on the exterior of the building. It is important to catch the problem early on because exterior troubles begin with an initial design defect and causes rapid aging. The scope of this study is seoul public borough offices that should be sustainable for long as landmark located at the center of the district. Field survey was conducted three times in six months. Twenty-six borough offices were diagnosed with three levels of contamination through visual inspection and the contaminated locations, types, materials, and characteristics were checked. Fourteen common contaminated locations were identified in the first and intensively rechecked in the second. Five locations vulnerable to contamination were designated and the contamination and cleanliness situations were checked by location in the third. As a result, main polluted types and locations are sloping wall, upper wall, protruded wall, canopy, and wall under window. The key to avoiding these pollution problems is to minimize the horizontal plane on which dust can be deposited. In other words, it can be considered variously by shape and location, such as the slope of the horizontal plane, the floating of the surface, the installation of the roof surface, and the vertical louvers. And throating plans and material plans suitable for each location are presented. Various methods of the shape and location, material are expected to use as useful basic data for preventing pollutions during the initial design stage.

• Journal of Convergence for Information Technology
• /
• v.11 no.2
• /
• pp.10-15
• /
• 2021

In this paper, we formed perovskite (CH3NH3PbI3) thin films on glass with wet coating methods, and used various analytical techniques to discuss film thickness, surface roughness, crystallinity, composition, and optical property. The coated semiconductor material has no defects and is uniform, the surface roughness value is very small, and a high absorption rate has been observed in the visible light area. Next, in order to implement the hole shape in the organic-inorganic layer, Samples in the order of a metal mask with holes at regular intervals, a glass coated with a perovskite material, and a magnet were etched with atmospheric pressure plasma equipment. The shape of the hole formed in the perovskite material was analyzed by changing the time. It can be seen that more etching is performed as the time increases. The sample with the longest processing time was examined in more detail, and it was classified into 7 regions by the difference according to the location of the plasma.

• Korean Journal of Metals and Materials
• /
• v.49 no.9
• /
• pp.732-738
• /
• 2011

Silicon oxide thin films were deposited by using a plasma-enhanced chemical-vapor deposition technique to investigate the light emission properties. The photoluminescence characteristics were divided into two categories along the relative ratio of the flow rates of $SiH_4$ and $N_2O$ source gases, which show light emission in the broad/visible range and a light emission peak at 380 nm. We attribute the broad/visible light emission and the light emission peak to the quantum confinement effect of nanocrystalline silicon and the Si=O defects, respectively. Changes in the photoluminescence spectra were observed after the post-annealing processes. The photoluminescence spectra of the broad light emission in the visible range shifted to the long wavelength and were saturated above an annealing temperature of $900^{\circ}C$ or after 1 hour annealing at $970^{\circ}C$. However, the position of the light emission peak at 380 nm did not change at all after the post-annealing processes. The light emission intensities at 380 nm initially increased, and decreased at annealing temperatures above $700^{\circ}C$ or after 1 hour annealing at $700^{\circ}C$. The photoluminescence behaviors after the annealing processes can be explained bythe size change of the nanocrystalline silicon and the density change of Si=O defect in the films, respectively. These results support the possibility of using a silicon-based light source for Si-optoelectronic integrated circuits and/or display devices.

• Journal of the Korean Institute of Gas
• /
• v.25 no.6
• /
• pp.14-21
• /
• 2021

Inner shell material of LNG storage tanks that store ultra-low temperature LNG at -162℃ requires structural integrity assessment of a crack-like defect. From the viewpoint of conventional fracture mechanics, the assessment has mainly performed by single parameter using stress intensity factor K, J-integral and CTOD. However, the stresses in a material of crack tip are not unique caused by constraint loss due to size and geometry of the structure. Various attempts have been made to complement a single parameter fracture mechanics, typically with Q-stress. In this paper, we have performed a two-parameter approach by deriving the Q-stress coupling with J-integral suitable for the evaluation of the crack tip stress field in the non-linear elastic region. A quantitative evaluation of the constraint effect has performed by using the J-Q approach. It was evaluated that the SENB type specimen had a crack ratio of 0.1 to 0.7 and the wide type specimen had a crack ratio of 0.2 to 0.6.