• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.286-289
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• 2004

This paper presents the fatigue characteristics of LIPCA (LIghtweight Piezo-Composite Actuator) device system. The LIPCA device system is composed of a piezoelectric ceramic layer and fiber reinforced lightweight composite layers. Typically a PZT ceramic layer is sandwiched by a top fiber layer with low CTE (coefficient of thermal expansion) and base layers with high CTE. The advantages of the LIPCA design are weight reduction by using the lightweight fiber reinforced plastic layers without compromising the generation of high force and large displacement and design flexibility by selecting the fiber direction and the size of prepreg layers. To predict the degradation of actuation performance of LIPCA due to fatigue, the cyclic electric loading tests using PZT specimens were performed and the strain for a given excitation voltage was measured during the test. The results from the PZT fatigue test were implemented into CLPT (Classical Laminated Plate Theory) model to predict the degradation of LIPCA's actuation displacement. The fatigue characteristic of PZT was measured using a test system composed of a supporting jig, a high voltage power supplier, data acquisition board, PC, and evaluated.

• Computers and Concrete
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• v.25 no.5
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• pp.401-409
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• 2020

Artificial neural networks are used as a useful tool in distinct fields of civil engineering these days. In order to control long-term quality of Self-Compacting Semi-Lightweight Concrete (SCSLC), the 90 days compressive strength is considered as a key issue in this paper. In fact, combined artificial neural networks are used to predict the compressive strength of SCSLC at 28 and 90 days. These networks are able to re-establish non-linear and complex relationships straightforwardly. In this study, two types of neural networks, including Radial Basis and Multilayer Perceptron, were used. Four groups of concrete mix designs also were made with two water to cement ratios (W/C) of 0.35 and 0.4, as well as 10% of cement weight was replaced with silica fume in half of the mixes, and different amounts of superplasticizer were used. With the help of rheology test and compressive strength results at 7 and 14 days as inputs, the neural networks were used to estimate the 28 and 90 days compressive strengths of above-mentioned mixes. It was necessary to add the 14 days compressive strength in the input layer to gain acceptable results for 90 days compressive strength. Then proper neural networks were prepared for each mix, following which four existing networks were combined, and the combinatorial neural network model properly predicted the compressive strength of different mix designs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.4080-4097
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• 2020

In recent years, convolutional neural network (CNN) has become the primary method for face detection. But its shortcomings are obvious, such as expensive calculation, heavy model, etc. This makes CNN difficult to use on the mobile devices which have limited computing and storage capabilities. Therefore, the design of lightweight CNN for face detection is becoming more and more important with the popularity of smartphones and mobile Internet. Based on the CPU real-time face detector FaceBoxes, we propose a multi-task lightweight face detector, which has low computing cost and higher detection precision. First, to improve the detection capability, the squeeze and excitation modules are used to extract attention between channels. Then, the textual and semantic information are extracted by shallow networks and deep networks respectively to get rich features. Finally, the landmark detection module is used to improve the detection performance for small faces and provide landmark data for face alignment. Experiments on AFW, FDDB, PASCAL, and WIDER FACE datasets show that our algorithm has achieved significant improvement in the mean average precision. Especially, on the WIDER FACE hard validation set, our algorithm outperforms the mean average precision of FaceBoxes by 7.2%. For VGA-resolution images, the running speed of our algorithm can reach 23FPS on a CPU device.

• Annual Conference of KIPS
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• 2021.11a
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• pp.704-707
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• 2021

Pigs' aggressive behavior represents one of the common issues that occur inside pigpens and which harm pigs' health and welfare, resulting in a financial burden to farmers. Continuously monitoring several pigs for 24 hours to identify those behaviors manually is a very difficult task for pig caretakers. In this study, we propose a lightweight video-based approach for monitoring pigs' aggressive behavior that can be implemented even in small-scale farms. The proposed system receives sequences of frames extracted from an RGB video stream containing pigs and uses MnasNet with a DM value of 0.5 to extract image features from pigs' ROI identified by predefined annotations. These extracted features are then forwarded to a lightweight LSTM to learn temporal features and perform behavior recognition. The experimental results show that our proposed model achieved 0.92 in recall and F1-score with an execution time of 118.16 ms/sequence.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.3
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• pp.254-262
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• 2024

The demand for high strength and ultra-lightweight materials to incorporate the advanced technology of nanomaterials into the lengthening of structures is continuously increasing. Therefore, based on existing research results and numerous mixing trials, we derived a mix of high strength and ultra-light concrete of a compressive strength of 100 MPa with a unit weight of 18 kN/m³ and a compr essive str ength of 80 MPa with a unit weight of 16 kN/m³ and evaluated their per for mance. In this paper, 108 specimens corresponding to high strength and ultra-lightweight concrete with a compressive strength of 100 MPa under a unit weight of 18 kN/m³, and a compressive strength of 80 MPa under a unit weight of 16 kN/m³ were manufactured, and the bond characteristics were identified by performing a directly tensile tests, and the bond characteristics were evaluated by comparing them with the experimental results and the current design criteria. It was judged that the bond strength calculation formula of ACI-408R and the experimental results were not accurately reflected, so an bond stress equation based on ACI-408R was proposed. The result of the proposed equation was that the deviation was somewhat reduced. In addition, the results of calculating the CEB-FIP model and the modified CMR model using statistical analysis showed slight differences from the experimental results, but considering that the bond behavior is a local behavior, the proposed model appears to explain the bond behavior of high strength and ultra-light concrete as a whole.

• Journal of Digital Convergence
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• v.10 no.3
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• pp.137-142
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• 2012

This paper proposes a software development guidance and an evaluation index for the productivity related to Spring 2.5 and EJB 3.0 with same lightweight container architecture. Spring is a known successful open source standard model for lightweight container architecture. EJB in an enterprise environment as a standard framework is most commonly used in production. However, there is no comparison research about the performance of Spring 2.5 and EJB 3.0 Framework with same identical platform. Quantitative analysis is supported as a part of LoC(Line of Code) analysis. There is a limit to develop the updated software with no the specific evaluating index for the productivity of the software. In this study, the development platform environment based on the same pilot system Spring 2.5 and EJB 3.0 framework is in the design and implementation. In addition, comparison and standardization of software development productivity assessment is to provide guidance.

• Spatial Information Research
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• v.21 no.3
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• pp.79-87
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• 2013

The purpose of this study focuses on the development of the lightweight BIM shape format(LBSF) structure to present the large volume BIM geometry object based on GIS as the viewpoint of the building facility management. Recently, the BIM-based facility management with GIS is researching with the purpose of the urban facility management etc. To implement these use-cases, the BIM geometry objects can be visualized based on urban level with GIS effectively. To do this, the lightweight BIM shape format is designed with the considerations and the prototype for the pilot test is implemented. In the pilot test phase, after developing the IFC file and LBSF file about the model data of the three areas, the performance with the data volume, the screen loading time etc was compared.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.9
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• pp.778-782
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• 2007

In the present study, design and forming process of fabricating titianium lightweight components are developed with applicaton of superplastic forming and diffusion bonding technology. SPF/DB(Superplastic forming/Diffusion bonding) technology is one of the advanced technologies to reduce production cost and weight and currently applied to aircrafts and space launchers in foreign countries. The present study constructs an analysis model to predict superplastic forming behavior of titanium alloy, which is well known for its resistance to deform. The experimental results show the forming of titanium lightweight sandwich structure is successfully performed from 3 sheets of Ti-6Al-4V. The results demonstrate that the developed technology to process design of SPF/DB by the finite element method can be applied to various types of components.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.545-550
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• 2016

The main purpose of this study is to analyze and evaluate the feasibility of ligthweight pavement system with pile foundation on soft soil by laboratory small chamber test. In order to verify the stability of lightweight pavement system, the 1/30 scaled downed model system was tested at lab. The soft soil condition was simulated and group piles for skin friction resistance were used. Within the limited lab test, the settlements of pavement system were 0.86 mm for Case A, 0.70 mm for Case B, and 0.50 mm for Case C. The converted maximum settlement differential settlement were 25.8 mm and 10.8 mm. These values meet the inside of specification of Bridge Design Guide in Korea. The use of lightweight pavement systems on soft soils could be an alternative construction method on soft soils to reduce the challenges of conventional design and constructions.

• Journal of the Korea Society for Simulation
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• v.20 no.4
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• pp.1-11
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• 2011

In the development phase of a torpedo, the effectiveness analysis is carried out to predict the performance and to learn how to use the torpedo. In order to obtain reliable data, it is required to model the tactical situation closely to the actual one. Because the submarine is a target of a lightweight torpedo, the anti-torpedo countermeasures of a submarine such as evasive maneuvering and TACM (Torpedo Acoustic Counter Measure) should be modeled in detail. In this paper, the evasive maneuvering is modeled reflecting the movement characteristics of the submarine. Furthermore various TACMs such as a floating-type decoy, a self-propelled decoy and jammers are also modeled. Then, effectiveness of a lightweight torpedo is measured and analyzed using the simulation program which is developed through the above modeling procedure.