• Journal of Advanced Navigation Technology
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• v.22 no.4
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• pp.295-301
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• 2018

Recently, GPS(Global Positioning System) array antenna technology is generally used and widely adopted as a national infrastructure structure and aero-vehicles for protection the GPS signal reception. Until now, the 2-dimensional planar array is universally used for its applications in the array antenna signal processing, however relatively higher altitude air vehicles such as UAV experiences additional null zones induced by low altitude GPS interferences which is located in a symmetry zone of antenna horizontal plane and this could make the receiving antenna pattern coverage reduction. In this paper, we improved 20% of the beam pattern receiving performance and 13 dB correlation value improvement by eliminating the interference mirror images.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.10
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• pp.83-92
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• 2019

A pump is considered to be submersible when a motor and a pump are integrated and operate while submerged in water. Submersible pumps mainly function as rejection pumps to prevent foods in densely populated areas, as cold water circulation pumps in large power plants, as pumps to supply irrigation water, as drainage pumps to prevent flooding of agricultural lands, as water supply intake pumps, and as inflow pumps for sewage treatment. The flow in such turbomachines (submersible pumps) inevitably involves various eddy currents. Since it is almost impossible to accurately grasp the complex three-dimensional flow structure and characteristics of a rotating turbomachine through actual testing, three-dimensional numerical analysis using computational fluid dynamics techniques measuring the flow field, velocity, and the pressure can be accurately predicted. In this study, the shape of the impeller was developed to reduce vibration and noise. This was done by increasing the efficiency of the existing submersible pump and reducing turbulence. In order to evaluate the pump's efficiency and turbulence reduction, we tried to analyze the flow using ANSYS Fluent V15.0, a commercial finite element analysis program. The results show that the efficiency of the pump was improved by 4.24% and the Reynolds number was reduced by 15.6%. The performance of a developed pump with reduced turbulence, vibration, and noise was confirmed.

• The Journal of Korean Society for School & Community Health Education
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• v.15 no.3
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• pp.81-93
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• 2014

Objectives: This study aims to find status of the oral health care, the oral health education program utilization and the oral health guidance according to the experience status of oral health education of special school teachers. Methods: The study subjects were 133 teachers at special schools in Seoul, Gyeonggi, Chungbuk and Jeonbuk regions. Results: 32.8% of the male and 67.2% of the female teachers have the oral health education experience. Barriers for the dental treatment to teachers with the education experience show in the order as 'disabled children's noncooperation' 49.2%, 'economic reasons' 37.7% and 'medical institution's rejection' 6.6% and, to teachers without the education experience, 'disabled children's noncooperation' 45.8%, 'economic reasons' 19.4% and 'not emergency situation' 13.9%(p<0.01). Regarding the necessity of arranged institution to manage the oral health, 91.8% of teachers with the oral health education answer as 'necessary'(p<0.05). Regarding the barriers on the performance of oral health program 27.9%, the majority of teachers with the education experience answer as 'insufficient administrative & financial support' and 36.1%, the majority of teachers without the education experience answer as 'insufficient understanding and expertise on the oral health education'. 86.9% of the teachers with the education experience and 62.5% of the teachers without the education experience are found to 'guide students on the oral health'(p<0.01). Conclusions: It was considered that various oral health education programs positively influential to the oral health care and education for disabled children should be developed according to the status of oral health education experience of special school teachers.

• Journal of IKEEE
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• v.23 no.2
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• pp.586-593
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• 2019

In this paper, we introduce the wood pellet electric power generation system, which is an eco - friendly solid fuel processed pure wood, which is one of the largest capacity renewable power fuels in Korea, The Ministry of Commerce, Industry and Energy notified the Ministry of Land, Infrastructure, Transport and Tourism of the Ministry of Land, Transport and Maritime Affairs of the Ministry of Land, Transport and Maritime Affairs. Derived and validated. It is confirmed that the performance of the generator and the voltage control characteristics of excitation system are good even for the change of generator fuel. It can contribute to future reference at the plant that wants to replace fossil fuels with renewable fuels.

• International journal of advanced smart convergence
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• v.7 no.4
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• pp.50-56
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• 2018

The Internet of Things (IoT) and Visible Light Communication (VLC) is opening up new services in lighting industry by integrating sensory network features in addition to standard illumination functionality. In this progressive developments, the next generation lighting devices for smart homes are capable to sense the environmental conditions and transfer the captured data through lights to gateway controller to access remotely. The smart home environmental sensor information's are few kbps only so VLC systems need to built-in with low rate light connectivity to transfer data to the gateway. To provide error free communication, the quality of a received light signal is important to be considered when designing an VLC receiver. Therefore, this paper proposes the design of robust low rate IoL receiver design using NCP302 voltage detector for micro controller to adapt the IoT/IoL front end module for system integration. To evaluate the proposed system performance, the Arduino UNO based IoT/IoL controller designed with lighting, sensors and lights connectivity interfaces. The experimental result shows that the robust interference rejection is feasible on proposed VOL receiver and possible to have an error-free communication up to 10 kbps at a low SNR using OOK modulation.

• Membrane and Water Treatment
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• v.10 no.4
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• pp.287-298
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• 2019

Lotus leaf has a special dual micro and nano surface structure which gives its highly hydrophobic surface characteristics and so-called self cleaning effect. In order to endow PVDF hollow fiber membrane with this special structure and improve the hydrophobicity of membrane surface, PVDF hollow fiber composite membranes was obtained through the immersion coating of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) dilute solution on the outside surface of PVDF support membrane. The prepared PVDF composite membranes were used in the vacuum membrane distillation (VMD) for the desalination. The effects of PVDF-HFP dilute solution concentration in the dope solution and coating time on VMD separation performance was studied. Membranes were characterized by SEM, WCA measurement, porosity, and liquid entry pressure of water. VMD test was carried out using $35g{\cdot}L^{-1}$ NaCl aqueous solution as the feed solution at feed temperature of $30^{\circ}C$ and the permeate pressure of 31.3 kPa. The vapour flux reached a maximum when PVDF-HFP concentration in the dilute solution was 5 wt% and the coating time was kept in the range of 10-60 s. This was attributed to the well configuration of micro-nano rods which was similar with the dual micro-nano structure on the lotus leaf. Compared with the original PVDF membrane, the salt rejection can be well maintained which was greater than 99.99 % meanwhile permeation water conductivity was kept at a low value of $7-9{\mu}S{\cdot}cm^{-1}$ during the continuous testing for 360 h.

• Journal of Advanced Navigation Technology
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• v.23 no.4
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• pp.273-280
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• 2019

There are many studies that use structure health monitoring to reduce maintenance costs for aircraft and to increase aircraft utilization. Many studies on FBG sensors are also being conducted. However, if the FBG sensor is installed inside the composite, voids will occur between the layers of the composite, resulting in signal split problem. In addition, the FBG sensor is not affected by electromagnetic waves, but will produce electromagnetic noise caused by electronic equipment during post-processing. In this paper, to reduce the error caused by these noises, the stationary wavelet transform, which has the characteristics of movement immutability and is efficient in nonlinear signal analysis, is presented. And in the above situation, we found that noise rejection performance of stationary wavelet transform was better compared with the wavelet packet transform.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.11
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• pp.911-920
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• 2018

In this study, we performed a study to track the angle between the guided weapon and the target by using the strap-down image seeker, and constructed a test bed that can simulate it visually. This paper describes a method to maintain high-performance feature distribution in the implementation of sparse feature tracking algorithm such as Lucas Kanade's optical flow algorithm for target tracking using image information. We have extended the feature tracking problem to the concept of feature management. To realize this, we constructed visual environment using Unity3D engine and developed image processing simulation using OpenCV. For the co-simulation, dynamic system modeling was performed with Matlab Simulink, the visual environment using Unity3D was constructed, and computer vision work using OpenCV was performed.

• Korean Journal of Schizophrenia Research
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• v.23 no.1
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• pp.29-37
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• 2020

Objectives: This study aimed to investigate the characteristics of early maladaptive schemas and their associations with clinical symptoms in patients with schizophrenia. Methods: Forty-eight patients with schizophrenia, 49 patients with major depressive disorder, and 50 healthy controls completed the Young Schema Questionnaire and symptom measures including the Brief Psychiatric Rating Scale-Expanded (BPRS-E). Results: The schizophrenia group had significantly higher scores than the healthy controls and lower scores than the depression group in most schemas. Compared with healthy controls, the schizophrenia group exhibited higher scores in 10 schemas, i.e., mistrust, social isolation, failure, dependence, vulnerability to harm, enmeshment, insufficient self-control, subjugation, emotional inhibition, and negativity schemas (all p<0.001). Moreover, vulnerability to harm, enmeshment, subjugation, and negativity schemas were correlated with total scores of the BPRS-E (0.37≤r≤0.43, all p<0.05). Regarding the five BPRS domains, emotional deprivation schema showed significant relationships with negative (r=0.50, p=0.005) and disorganization (r=0.39, p=0.033) symptoms, while no schemas showed correlations with positive symptoms. Conclusion: These results suggest that most schemas in patients with schizophrenia pertain to impaired autonomy and performance as well as disconnection and rejection domains and may improve our understanding and the treatment of schizophrenia from a perspective of schema therapy focused on these domains.

• Journal of IKEEE
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• v.27 no.4
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• pp.518-523
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• 2023

The diagnosis of Inter Turn Short Circuits (ITSC) in induction motors is critical due to the escalating severity of faults resulting from even minor disruptions in the stator windings. However, diagnosing ITSC presents significant challenges due to similarities in noise and losses shared with 3-phase induction motors. Although artificial intelligence techniques have been explored for efficient diagnosis, practical applications heavily rely on model-based methods, necessitating further research to enhance diagnostic performance. This study proposed a diagnostic method applied the Clarke Transformation approach, focusing solely on current components while disregarding changes in rotating flux. Experimental results conducted over a 30-minute period, encompassing both normal and ITSC conditions, demonstrate the effectiveness of the proposed approach, with FAR(False Accept Rates) of 0.2% for normal-to-ITSC FRR(False Rejection Rates) and 0.26% for ITSC-to-normal FRR. These findings underscore the efficacy of the proposed approach.