• Composites Research
• /
• v.35 no.3
• /
• pp.201-215
• /
• 2022

This paper presents the development of thin and lightweight ultra-high temperature radar-absorbing ceramic composites composed of an aluminosilicate ceramic matrix-based geopolymer reinforced ceramic fiber and sendust magnetic nanoparticles in X-band frequency range (8.2~12.4 GHz). The dielectric properties with regard to complex permittivity of ceramic/sendust-aluminosilicate composites were proportional to the size of sendust magnetic nanoparticle with high magnetic characteristic properties as flake shape and its concentrations in the target frequency range. The characteristic microstructures, element composition, phase identification, and thermal stability were examined by SEM, EDS, VSM and TGA, respectively. The fabricated total thicknesses of the proposed single slab ultra-high temperature radar absorber correspond to 1.585 mm, respectively, exhibiting their excellent EM absorption performance. The behavior of ultra-high temperature EM wave absorption properties was verified to the developed free-space measurement system linked with high temperature furnace for X-band from 25℃ to 1,000℃.

• Journal of the Korean Society of Radiology
• /
• v.16 no.7
• /
• pp.935-942
• /
• 2022

In doing interventional treatment under the guidance of ultrasonography, the medical team detects the legion site with ultrasonic equipment at first, and insert angio needle. In this situation, if the position of legion and the depth of inserted needle on the ultrasonographic screen are different from real position and depth, the needle is likely to damage a major blood vessel or tissue. Accordingly, we had wondered how much such differences between screen image and reality, and so decided to examine them. Using five ultrasonographic equipments manufactured from different companies in different years, this study tried to compare the lengths of the needle on the screen images and real lengths of it, and find out the factors affecting skewness of them. This study used hog meat chunk to mimic human flesh, and sausages as the target of needle. It compared penetrating depths of the needle as the images on the five equipments using single sample t test in the SPSS 22 statistical program. It was found that all the errors were statistically significant(<.05). So, this study decided that it was wrong to evaluate performances of the equipments by the makers and ages of them. It is necessary to do periodic quality controls of equipments and improve the skillfulness of sonographers to reduce error rates between real treatment areas and the images of them.

• Therapeutic Science for Rehabilitation
• /
• v.11 no.4
• /
• pp.7-22
• /
• 2022

Objective : This study aims to provide clinical evidence by systematically reviewing domestic CO-OP intervention studies. Methods : 13 papers suitable for selection criteria were finally selected and conducted. The analysis was divided into general characteristics and qualitative levels. Results : As a result of analyzing the contents of study, research has been conducted continuously since 2015, and the level of evidence for CO-OP intervention study was mainly single subject design. The subjects of the study were applied to both children and adults, and as the target activity areas of CO-OP intervention, children were shown to be play and leisure, and adults were instrumental daily living. COPM/PQRS were frequently used for evaluation to examine effectiveness of interventions. For domain specific strategies, children used body position, attention to doing, task specification, and verbal motor mnemonic. For adults, body position, attention to doing, task specification, and feeling to movement, verbal motor mnemonic, verbal rote script were used. Conclusion : It was found that CO-OP intervention is continuously being applied in occupational therapy, and age and diagnosis group are expanding. It is significant in that it provided evidence for implementing CO-OP interventions in clinical practice through a systematic review of domestic CO-OP intervention studies.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.11
• /
• pp.801-807
• /
• 2022

In this paper, we propose an ultra compact S-Band PCM/FM telemetry transmitter. The equipment is compact, so it can be applied to a limited space and capable of stable data transmission was designed and manufactured even with specifications set differently for each operating environment and system. RF direct conversion structure is used for the miniaturization of equipment, an RF transmission board, Power distribution board, and a signal processing board were implemented on a single PCB, so that the function of the transmitter could be performed with a minimum device. According to the target specification, variable output of 1~10W and variable data rate of 390kbps~12.5Mbps is possible in S-Band(2,200~2,400MHz) without degradation of performance. To verify the performance of the equipment, the RF performance test and BER measurement test were performed after the equipment was manufactured. It was confirmed that the OBW, null-to-null bandwidth, 1st IMD, Spurious emission, Phase noise specification of the PCM/FM modulated signal which is presented by the IRIG standard were satisfied, and we can confirm the data received using the transmitter inspection equipment were transmitted normally without distortion.

• International conference on construction engineering and project management
• /
• 2022.06a
• /
• pp.1243-1244
• /
• 2022

In recent years, the growing interest in off-site construction has led to factories scaling up their manufacturing and production processes in the construction sector. Consequently, continuous large-scale site monitoring in low-variability environments, such as prefabricated components production plants (precast concrete production), has gained increasing importance. Although many studies on computer vision-based site monitoring have been conducted, challenges for deploying this technology for large-scale field applications still remain. One of the issues is collecting and transmitting vast amounts of video data. Continuous site monitoring systems are based on real-time video data collection and analysis, which requires excessive computational resources and network traffic. In addition, it is difficult to integrate various object information with different sizes and scales into a single scene. Various sizes and types of objects (e.g., workers, heavy equipment, and materials) exist in a plant production environment, and these objects should be detected simultaneously for effective site monitoring. However, with the existing object detection algorithms, it is difficult to simultaneously detect objects with significant differences in size because collecting and training massive amounts of object image data with various scales is necessary. This study thus developed a large-scale site monitoring system using edge computing and a small-object detection system to solve these problems. Edge computing is a distributed information technology architecture wherein the image or video data is processed near the originating source, not on a centralized server or cloud. By inferring information from the AI computing module equipped with CCTVs and communicating only the processed information with the server, it is possible to reduce excessive network traffic. Small-object detection is an innovative method to detect different-sized objects by cropping the raw image and setting the appropriate number of rows and columns for image splitting based on the target object size. This enables the detection of small objects from cropped and magnified images. The detected small objects can then be expressed in the original image. In the inference process, this study used the YOLO-v5 algorithm, known for its fast processing speed and widely used for real-time object detection. This method could effectively detect large and even small objects that were difficult to detect with the existing object detection algorithms. When the large-scale site monitoring system was tested, it performed well in detecting small objects, such as workers in a large-scale view of construction sites, which were inaccurately detected by the existing algorithms. Our next goal is to incorporate various safety monitoring and risk analysis algorithms into this system, such as collision risk estimation, based on the time-to-collision concept, enabling the optimization of safety routes by accumulating workers' paths and inferring the risky areas based on workers' trajectory patterns. Through such developments, this continuous large-scale site monitoring system can guide a construction plant's safety management system more effectively.

• Journal of the Korean Magnetics Society
• /
• v.5 no.2
• /
• pp.128-133
• /
• 1995

Yttrium Iron Garnet($Y_{3}Fe_{5)O_{12}$) films have been succsssfully grown on(111)GGG wafer by KrF excimer laser ablation of stoichiometric garnet target at the oxygen partial pressure, $P(O_{2}$, ranging 20 to 500 mTorr. During the deposition of the films the substrate temperature was maintained at $700^{\circ}C$ and the laser beam energy density at $7.75\;J/cm_{2}$. Microstructure, composition and magnetic properties of the films obtained were investigated as a function of oxygen pressure and thickness of the films. Epitaxial films with a dense and a smooth surface were reproducible at a low oxygen pressure. The films of $2.75\;{\mu}$ min thickness deposited at 20 mTorr of $P(O_{2})$ showed $4{\pi}M_{s}$ of 1500 Gauss and $H_{c}$ of 3 Oe after annealing at $800\;^{\circ}C$ for 20 minutes. As-deposited films of $0.8\;\mu\textrm{m}$ in thickness exhibited the $4{\pi}M_{s}$ of 1730 Gauss and $H_{c}$ of 7 Oe. The magnetic properties of the films obtained were almost identical to those of a single crystal YIG.

• Geophysics and Geophysical Exploration
• /
• v.25 no.4
• /
• pp.177-188
• /
• 2022

Recently, the application of distributed acoustic sensors (DAS), which can replace geophones and seismometers, has significantly increased along with interest in micro-seismic monitoring technique, which is one of the CO₂ storage monitoring techniques. A significant amount of temporally and spatially continuous data is recorded in a DAS monitoring system, thereby necessitating fast and accurate data processing techniques. Because event detection and seismic phase picking are the most basic data processing techniques, they should be performed on all data. In this study, a machine learning-based P, S wave phase picking algorithm was developed to compensate for the limitations of conventional phase picking algorithms, and it was modified using a transfer learning technique for the application of DAS data consisting of a single component with a low signal-to-noise ratio. Our model was constructed by modifying the convolution-based EQTransformer, which performs well in phase picking, to the ResUNet structure. Not only the global earthquake dataset, STEAD but also the augmented dataset was used as training datasets to enhance the prediction performance on the unseen characteristics of the target dataset. The performance of the developed algorithm was verified using K-net and KiK-net data with characteristics different from the training data. Additionally, after modifying the trained model to suit DAS data using the transfer learning technique, the performance was verified by applying it to the DAS field data measured in the Pohang Janggi basin.

• Journal of Popular Narrative
• /
• v.25 no.2
• /
• pp.217-245
• /
• 2019

Recently, the interest among Korean broadcasters in the 'observation entertainment' genre has intensified. This study aims to analyze the genre and storytelling of observation entertainment programming from a narratological perspective. The origin of the Korean observation entertainment program began with the 'reality-variety show'. There was a 'real-life' debate in these reality-variety shows, and as an alternative, the observation entertainment program appeared. Documentary filming, omnibus composition, and spatialization of 'everyday' life have led to the recognition of observation entertainment as a single genre. In particular, 'observers' have become a key factor in the observation entertainment program. The subject of the program is determined by who the observer is. The variability of the program format is the same. The observer looks at the observation target on behalf of the viewer. At the same time, he or she serves as a narrator of the program. The observer functions as the most influential factor in the storytelling of the observation entertainment program. In the observation entertainment program, 'observation' is only a form. It is the observer who creates a narrative within this same format to make the difference between each program. Also, voyeurism has been considered a problem in reality shows such as observation entertainment programs. However, the form communicated by observers is not a direct peek, so much of the problem of voyeurism is mitigated. Such observation entertainment programs analyzed through observers are meaningful in that they make people understand the cultural meaning of "reality" in TV and the storytelling of contemporary Korean TV entertainment.

• Journal of the Korean Society of Floral Art and Design
• /
• no.41
• /
• pp.13-24
• /
• 2019

The purpose of this study was to analyze research papers related to forest play of children's and present future research directions and basic data. 174 out of the forest play papers for children's provided to the research information sharing service (www. riss. kr) from 2009 to 2018 were studied. The number of papers according to the study was 114 published for children. Looking at the research method of forest play papers for children, 55.17% for experimental papers, 9.77% for observation papers, 17.82% for research papers, 5.75% for case studies, 6.32% for literature review papers and 5.17% for other papers. Looking at trends by target age, in the case of the papers which studied on the single age, the number of papers researching on age 3.51%) for 2 years old, 2.63% for the 3 years old, 9.65% for the 4 years old, 35.96% for the 5 years old. A total of 40.36% consisted of children aged between 2 and 5 years. A total of 7.89% were published for infants and children with handicapped. The number of theses that studied emotional development accounted for 30.7%, social development was 25.44%, cognitive development was 16.67%, self concept development was 14.04%, physical development was 6.14%, language development was 3.51% and other development was 3.51%. As a result of the above analysis, it was necessary to study the language development and the forest play.

• Asia Marketing Journal
• /
• v.15 no.3
• /
• pp.159-172
• /
• 2013

In the present study, we apply the multiple cue probability learning (MCPL) paradigm to examine consumer learning from feedback in repeated trials. This paradigm is useful in investigating consumer learning, especially learning the relationships between the overall quality and attributes. With this paradigm, we can analyze what people learn from repeated trials by using the lens model, i.e., whether it is knowledge or consistency. In addition to introducing this paradigm, we aim to demonstrate that knowledge people gain from repeated trials with feedback is robust enough to weaken one of the most often examined contextual effects, the asymmetric dominance effect. The experiment consists of learning session and a choice task and stimuli are sport rafting boats with motor engines. During the learning session, the participants are shown an option with three attributes and are asked to evaluate its overall quality and type in a number between 0 and 100. Then an expert's evaluation, a number between 0 and 100, is provided as feedback. This trial is repeated fifteen times with different sets of attributes, which comprises one learning session. Depending on the conditions, the participants do one (low) or three (high) learning sessions or do not go through any learning session (no learning). After learning session, the participants then are provided with either a core or an extended choice set to make a choice to examine if learning from feedback would weaken the asymmetric dominance effect. The experiment uses a between-subjects experimental design (2 × 3; core set vs. extended set; no vs. low vs. high learning). The results show that the participants evaluate the overall qualities more accurately with learning. They learn the true trade-off rule between attributes (increase in knowledge) and become more consistent in their evaluations. Regarding the choice task, there is a significant decrease in the percentage of choosing the target option in the extended sets with learning, which clearly demonstrates that learning decreases the magnitude of the asymmetric dominance effect. However, these results are significant only when no learning condition is compared either to low or high learning condition. There is no significant result between low and high learning conditions, which may be due to fatigue or reflect the characteristics of learning curve. The present study introduces the MCPL paradigm in examining consumer learning and demonstrates that learning from feedback increases both knowledge and consistency and weakens the asymmetric dominance effect. The latter result may suggest that the previous demonstrations of the asymmetric dominance effect are somewhat exaggerated. In a single choice setting, people do not have enough information or experience about the stimuli, which may lead them to depend mostly on the contextual structure among options. In the future, more realistic stimuli and real experts' judgments can be used to increase the external validity of study results. In addition, consumers often learn through repeated choices in real consumer settings. Therefore, what consumers learn from feedback in repeated choices would be an interesting topic to investigate.