• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.10
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• pp.8-19
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• 2019

In this study, the spray pattern of a centrifugal fertilizer distributor with two shutter holes was analyzed and an effective driving width that satisfies proper spray uniformity was derived. The centrifugal fertilizer distributor was mounted on a tractor with a rated power of 23.7 kW and static and dynamic spray pattern tests were performed according to the standard procedure proposed by the American Society of Agricultural and Biological Engineers Standard ASAE S341.5. The height of the fertilizer distributor was 80 cm from the ground and the PTO (power take-off) shaft speed of the tractor was fixed at 540 rpm. The fertilizer scattered in space was collected using 275 evenly spaced collectors at shutter opening ratios of 25%, 50%, 75%, and 100%. The spray pattern was analyzed via the amount of sprayed fertilizer at each collector location and the coefficient of variation was used as an indicator of spray uniformity. Using the analyzed spray pattern, the effective driving width that satisfied less than 15% of the coefficient of variation was derived for different tractor driving patterns (race track mode, back and forth mode). From the results, spray uniformity increased as the shutter opening ratio decreased. The largest effective driving width was 8 m at a shutter opening ratio of 25% for both driving patterns.

• Safety and Health at Work
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• v.5 no.4
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• pp.203-209
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• 2014

Background: Coal mining is of significant economic importance to the Australian economy. Despite this fact, the related workforce is subjected to a number of psychosocial risks and musculoskeletal injury, and various psychological disorders are common among this population group. Because only limited research has been conducted in this population group, we sought to examine the relationship between physical (pain) and psychological (distress) factors, as well as the effects of various demographic, lifestyle, and fatigue indicators on this relationship. Methods: Coal miners (N = 231) participated in a survey of musculoskeletal pain and distress on-site during their work shifts. Participants also provided demographic information (job type, age, experience in the industry, and body mass index) and responded to questions about exercise and sleep quality (on-and off-shift) as well as physical and mental tiredness after work. Results: A total of 177 workers (80.5%) reported experiencing pain in at least one region of their body. The majority of the sample population (61.9%) was classified as having low-level distress, 28.4% had scores indicating mild to moderate distress, and 9.6% had scores indicating high levels of distress. Both number of pain regions and job type (being an operator) significantly predicted distress. Higher distress score was also associated with greater absenteeism in workers who reported lower back pain. In addition, perceived sleep quality during work periods partially mediated the relationship between pain and distress. Conclusion: The study findings support the existence of widespread musculoskeletal pain among the coal-mining workforce, and this pain is associated with increased psychological distress. Operators (truck drivers) and workers reporting poor sleep quality during work periods are most likely to report increased distress, which highlights the importance of supporting the mining workforce for sustained productivity.

• Journal of KIBIM
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• v.11 no.3
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• pp.45-54
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• 2021

The augmented reality (AR) has recently became an attractive technology in construction industry, which can play a critical role in realizing smart construction concepts. The AR has a great potential to help construction workers access digitalized information about design and construction more flexibly and efficiently. Though several AR applications have been introduced for on-site made to enhance on-site and off-site tasks, few are utilized in actual construction fields. This paper proposes a new AR framework that provides on-site managers with an opportunity to easily access the information about construction resources such as workers and equipment. The framework records videos with the camera installed on a wearable AR device and streams the video in a server equipped with high-performance processors, which runs an object detection algorithm on the streamed video in real time. The detection results are sent back to the AR device so that menu buttons are visualized on the detected objects in the user's view. A user is allowed to access the information about a worker or equipment appeared in one's view, by touching the menu button visualized on the resource. This paper details implementing parts of the framework, which requires the data transmission between the AR device and the server. It also discusses thoroughly about accompanied issues and the feasibility of the proposed framework.

• Journal of Trauma and Injury
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• v.32 no.2
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• pp.107-110
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• 2019

Bilateral chylothorax due to blunt trauma is extremely rare. We report a 74-year-old patient that developed delayed bilateral chylothorax after falling off a ladder. The patient had a simple 12th rib fracture and T12 lamina fracture. All other findings seemed normal. He was sent home and on the 5th day visited our emergency center at Halla Hospital with symptoms of dyspnea and lower back pain. Computer tomography of his chest presented massive fluid collection in his right pleural cavity and moderate amounts in his left pleural cavity with 12th rib fracture and T11-12 intervertebral space widening with bilateral facet fractures. Chest tubes were placed bilaterally and chylothorax through both chest tubes was discovered. Conservative treatment for 2 weeks failed, and thus, thoracic duct ligation was done by video assisted thoracoscopic surgery. Thoracic duct embolization was not an option. Postoperatively, the patient is now doing well and happy with the results. Early surgical treatment must be considered in the old patient, whom large amounts of chylothorax are present.

• Particle and aerosol research
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• v.14 no.4
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• pp.89-95
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• 2018

People's environmental concerns for fine particles in Korea lead to the strong necessity of improving the performance of environmental control systems. Wet electrostatic precipitators (ESPs) are considered as one of the alternatives to overcome the limit of previous dry ESPs, the re-entrainment of collected particles during rapping and back corona problem for high electrical resistivity dusts etc. In this study, a wire-cylindrical ESP with a thin water film has been developed. Particle collection characteristics were compared in the ESP with operations of water film on and off. Particle collection efficiencies at various applied voltages as well as voltage-current curves were almost the same in the ESP with and without a water film. Particle collection performance for PM1.0, PM2.5 and PM10 in the wet ESP with a water film was constantly maintained with operation time even in the high dust loading environment. This results indicate that a uniform water film in our wet ESP was successfully formed with a very thin layer without any dry spot and therefore could continuously clean the collected particles on the inner wall of the ESP without any performance degradation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.4
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• pp.1293-1316
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• 2021

Using directional antennas in wireless Ad hoc networks has many superiorities, including reducing interference, extending transmission range, and increasing space division multiplexing. However, directional transmission introduces two problems: deafness and directional hidden terminals problems. We observe that these problems result in saturation throughput disparity among the competing flows in directional CSMA/CA based Ad hoc networks and bring challenges for modeling the saturation throughput of the flows. In this article, we concentrate on how to model and analyze the saturation throughput disparity of different flows in directional CSMA/CA based Ad hoc networks. We first divide the collisions occurring in the transmission process into directional instantaneous collisions and directional persistent collisions. Then we propose a four-dimensional Markov chain to analyze the transmission state for a specific node. Our model has three different kinds of processes, namely back-off process, transmission process and freezing process. Each process contains a certain amount of continuous time slots which is defined as the basic time unit of the directional CSMA/CA protocols and the time length of each slot is fixed. We characterize the collision probabilities of the node by the one-step transition probability matrix in our Markov chain model. Accordingly, we can finally deduce the saturation throughput for each directional data stream and evaluate saturation throughput disparity for a given network topology. Finally, we verify the accuracy of our model by comparing the deviation of analytical results and simulation results.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.85-89
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• 2022

We reported on annealing effect on Ga₂O₃/Al₂O₃/SiC devices grown by radio frequency sputtering method. Post-deposition annealing at 900 ℃ was performed, which results in crystallization in the Ga₂O₃ films. The major peaks (-401) and (403) of Ga₂O₃ which was thermally treated at 900 ℃ appears in the x-ray diffraction (XRD) results. Auger electron spectroscopy (AES) shows that Ga and Al atoms seems to be diffused into the opposite direction Al₂O₃ and Ga₂O₃ after annealing. Transfer and output characteristics of back-gate transistor were analyzed where SiC substrate is used as gate material. On-state current and on/off ratio increased almost 10⁹ and 10⁶ times higher in the 900 ℃ annealed sample.

• Journal of Industrial Convergence
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• v.20 no.7
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• pp.123-129
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• 2022

It was to establish the usage possibility as cosmetic material by testing stimulation of Leuconostoc mesenteroides which were cultured from human scalp's dead skin cell by patching it to the skin in the form of solubilized essence. Cultured L. mesenteroides diluted to 1% concentration and essence which contains it were patched to 31 and 32 participants' back each for 24 hours and established the stimulus figures by the specialists in 30 minutes, 24 hours, and 48 hours after they were taken off. They are both revealed as non-stimuli due to the result of 0.011 and 0 points each and therefore they are safe when used as skin products. Considering the results of this test and the other previous studies which reported the L. mesenteroides as anti-allergic, antioxidant, and anti-inflammatory, L. mesenteroides is usable for cosmetics and worth further research.

• Journal of architectural history
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• v.31 no.3
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• pp.41-52
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• 2022

This study explains the han-ok. in Gae-sung, which was antique and traditional city. In view of the fact that these were located in Gae-sung in North Korea hence direct investigate is not possible. Since there was no comprehensive study of Gaeseong han-ok, we have no choice but to rely on fragmentary records and memory of Gaeseong people. In accordance from the Japanese colonial era's surveys and sketches as well as how they were illustrated in the novel. Hark back to the peoples' thought of the han-ok years when they ran the survey in 1920s, the results were as follows: First, there are many houses so various classes in Mi-Mang. Jeon Cheo-man's house was a representative example of a rich family in Gae-sung, Jeon Je-seong(Jeon's 2^nd son)'s house was located in Si-jeon(government licensed-markets) near by the South gate. In particular, Jeon Yi-seong(Jeon's 3rd son)'s house was in rural areas. He managed on immense ginseng field and worker's houses. Hae-ju's house was a small house off the track. Second, the outer house is low and the main house is high and neat. Lastly, it was confirmed that it corresponded to sketches recorded by architects, such as neat housekeeping, long stones used for various purposes, invisible flat gates, the appearance of old and old houses and the composition of each room.

• The Korea Journal of Herbology
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• v.32 no.3
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• pp.89-95
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• 2017

Objectives : Seborrheic dermatitis is common abnormal skin condition characterized by flaking and itch. In seborrheic dermatitis, the flakes are greasy and yellowish. Inflammation is also observed. Through this paper we can understand the process of seborrheic dermatitis of the scalp and confirm the scalp changes in the treatment process. The purpose of this study was to report the clinical effects of herbal medicine on Seborrheic dermatitis Methods : We employed oriental medical treatments; herbal-medication (Hyeongbangpaedoksangamibang), infant acupuncture, moxibustion and blood therapy. We treated her three times a week. She took medicine three times a day after a meal. During taking medicine, we let her avoid fatty food, flour based food. Her father took a picture the patient's head parts and we compared the symptom with previous symptom. With the picture, we evaluated the patient's scalp condition. Results : After taking treatment, the scalp condition of the patient was much improved. At first, yellowish to reddish scaly pimples appear along the hairline and itching was severe. There were thick and black crusts on the scalp, red, greasy skin covered with flaky white or yellow scales. After that the crusts were fell off and the itching was disappeared during the treatment period. And then the hair loss was occurred. After a year of treatment, scalp condition and hair were back to normal. Conclusion : Herbal medicine (Hyeongbangpaedoksangamibang) with oriental medical treatments was effective in the treatment of seborrheic dermatitis of the scalp and it helped to improve regenerating the scalp condition.