• Journal of KSNVE
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• v.8 no.6
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• pp.1093-1102
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• 1998

The success of controllability of smart structures depends on the quality of the bonding along the interface between the main structure and the attached sensing and acuating elements. Generally, the analysis procedures neglect the effect of the interfacial bond layer or assume that this bond layer behaves like viscoelastic material. Three different bond layers. two modified epoxy adhesives, and one isocyanate adhesive were prepared for their toughness and moduli. Bond layer of the chosen adhesive provides an almost perfect bonding condition between the composite structure and the PZT while bended significantly like arrow-shape. The perfect bonding condition is tested by considering various material properties of the bond layers. and based on this perfect bonding condition, the effects of the interfacial bond layer on the dynamic behavior and controllability of the test structure is experimentally studied. Once the perfect bonding condition is achieved. dynamic effects of the bond layer itself on the dynamic characteristics of the main structure is negligible. but the contribution of the attached PZT elements on the stiffness of the multi-layered structure becomes significant when the thickness of the bond layer increased.

• Journal of Internet of Things and Convergence
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• v.8 no.1
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• pp.23-29
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• 2022

The product to be developed in this study is a heat recovery device which generates steam or hot water at high temperature and high pressure by heating water using exhaust gas from diesel engine, gas engine, gas turbine, etc. as an exhaust gas boiler off heat boiler(EGB) type for ship and power generation. The steam vapor or the created warm water is used as the power source required for the steerage heating and hot water facility or the HFO heating of the ship, and the turbine drive. The principle of waste heat boilers serves to heat water as high temperature exhaust gas with heat pass through the tube of the boiler. The heated water is a structure that is sent to a cabin or turbine device in the form of steam. In this study, the objective of this study is to maximize the efficiency by increasing the heat transfer surface by replacing the tube which is the heat transfer part of EGB with the plate tube.

• Composites Research
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• v.31 no.4
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• pp.151-155
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• 2018

Mechanical joint and adhesive joint are two typical joining methods for structures. The adhesive joints distribute the load over a larger area than mechanical joints and have excellent fatigue properties. However, the strength of adhesive joint greatly depends on the environmental conditions and the skill of the operator. Therefore, there is a need for techniques to evaluate the quality of the adhesive joints. The electric resistance method is a very promising technique for detecting defects by measuring the electrical resistance of an adhesive joint in which CNTs are dispersed in an adhesive. In this study, Aluminium-Aluminium adhesive single lap joint specimens were fabricated by using the adhesive dispersing CNTs using a sonicator and a 3-roll mill, and the static strengths and defect detection capabilities of the joints using the electrical resistance method were evaluated according to the CNTs content.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.649-655
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• 2020

This study determined effective educational strategies by investigating and analyzing the related educational demands for SMEs (small and medium-sized enterprises) in the 4th Industrial Revolution based area of smart farms. In order to derive the approprate educational strategies, Importance-Performance Analysis (IPA) and Borich's Needs Assessment Model were conducted based on the smart farm technological field. As a result, the education demand survey showed high demand for production systems and intelligent farm machinery. In detail, Borich's analysis showed the need for pest prevention and diagnosis technology (8.03), network and analysis SW linkage technology (7.83), and intelligent farm worker-agricultural power system-electric energy hybrid technology (7.43). In contrast, smart plant factories (4.09), lighting technology for growth control (4.46) and structure construction technology (4.62) showed low demands. Based on this, the IPA portfolio shows that the network and analysis SW linkage technology and the CAN-based complex center are urgently needed. However, the technology that has already been developed, such as smart factory platform development, growth control lighting technology and structure construction technology, was oversized. Based on these results, it is possible to strategically suggest the customized training programs for industrial sectors of SMEs that reflect the needs for efficiently operating smart farms. This study also provides effective ways to operate the relevant training programs.

• Sleep Medicine and Psychophysiology
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• v.5 no.1
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• pp.54-70
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• 1998

Objectives : The purpose of this study is to evaluate the role of structural and functional changes of the brain in the pathophysiology of schizophrenia. Methods : The authors measured the regions of interest on the magnetic resonance imaging of the brain in 20 patients with paranoid schizophrenia(15 men and 5 women) and 23 control subjects(15 men and 8 women). We also assessed the neurocognitive functions with the Wisconsin Card Sorting Test, the Benton Neuropsychological Assessment, and the Weschler IQ test-Korean version, soft neurologic signs, and psychiatric symptoms in the patient group. Results : In the patient group, all ventricles and basal ganglia including caudate nucleus and globus pallidus were significantly enlarged. Although there were no significant differences between the two groups in the values of right frontal lobe and left temporal lobe, there was a tendency of decrease in the values of right frontal lobe and left temporal lobe. There were significant positive correlations between the values of ventricles and the frequency of previous hospitalization. However, there were no significant correlations between other values of regions of interest and clinical data. The value of the right frontal lobe was significantly correlated with the score of soft neurologic signs, which is suggestive of the neurodevelopmental abnormalities. There were significant correlations between the value of frontal lobe and the scores of the various subscales of Benton Neuropsychiatric Inventory. In contrast, the value of left amygdala and putamen showed significant correlation with the score of verbal IQ on the Weschler IQ test. Structural changes of the temporal lobe areas were related with the positive and general symptom scores on PANSS, while those of the basal ganglia were related with the negative symptom scores. Conclusions : These results suggest that the structural changes of the brain in the patients with schizophrenia show the dual process, which is suggestive that the enlarged ventricle show the neurodegenerative process, while enlarged basal ganglia, and shrinked right frontal and left temporal lobe show the neurodevelopmental abnormalities. Among these changes, structural changes of the frontal lobe related with various neuropsychological deficits, while those of left temporal lobe related with language abnormality. Relative to the relation between structural changes and psychiatric symptoms, structural changes of the temporal lobe areas were related with the positive and general symptoms, while those of the basal ganglia were related with the negative symptoms.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.60-66
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• 2006

The purpose of this paper is to evaluate potential application of Lightweight Piezo-composite Actuator (LIPCA) to suppress vibrations of structures. The LIPCA, consisting of a piezoelectric layer, a carbon/epoxy layer and glass/epoxy layers, has advantages in terms of high performance, durability and reliability, compared to the bare piezoelectric ceramic (PZT) actuator. We performed two kinds of experiments on static actuation and active vibration suppression to investigate the actuation performances of the LIPCA and the bare PZT. We attached the actuator on one side and a strain gage on the other side of an aluminum beam. In the static actuation test, we evaluated the performance by comparing equivalent actuation moments of the LIPCA and the bare PZT due to the applied voltage. In the active vibration control test, control signals were generated to suppress the vibration of the beam by the PID control algorithm based on the measured strain signals. The performances were estimated based on settling times of the strain responses. It can be concluded that the LIPCA has better actuation performances than the bare PZT in active control of free vibration as well as static actuation.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.824-829
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• 2016

Passenger casualties in the case of ship accidents have increased because of the increase in size and complexity of current ships (such as cruise ships). Therefore, in recent years, emergency evacuation systems are receiving increased interest so as to ensure the safety of passengers. Currently, there are only basic instructions provided, such as announcements regarding the situation, alarms, and exit signs; however, no guidance toward a proper escape route has yet been provided. To solve this problem, several emergency guiding schemes have been proposed. However, these systems ignore some of the realities of ship accidents and are impractical because various risk factors are not considered. Therefore, this paper proposes an optimal route guiding system based on an $A^*$ algorithm for emergency escape during disaster situations. This system takes into account various possible risk factors. Performance evaluation using computer simulations showed that the proposed scheme is effective and leads to safe escape routes.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.51-61
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• 2006

An efficient and accurate hybrid reliability analysis method is proposed in this paper to quantify the risk of an axially loaded single pile considering pile-soil interaction behavior and uncertainties in various design variables. The proposed method intelligently integrates the concepts of the response surface method, the finite difference method, the first-order reliability method, and the iterative linear interpolation scheme. The load transfer method is incorporated into the finite difference method for the deterministic analysis of a single pile-soil system. The uncertainties associated with load conditions, material and section properties of a pile and soil properties are explicitly considered. The risk corresponding to both serviceability limit state and strength limit state of the pile and soil is estimated. Applicability, accuracy and efficiency of the proposed method in the safety assessment of a realistic pile-soil system subjected to axial loads are verified by comparing it with the results of the Monte Carlo simulation technique.