• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.13-13
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• 2010

Switching an elementary excitation by injecting a single carrier would offer the exciting opportunity for the ultra-high data storage technologies. However, there has been no methodology available to investigate the interaction of low energy discrete carriers with nano-structures. In order to map out the spatial dependency of such single carrier level interactions, we developed a pulse-and-probe algorithm, combining with low temperature scanning tunneling microscopy. The new tool, which we call single carrier spectroscopy, allows us to track the interaction with the target macrostructure with tunneling carriers on a single carrier basis. Using this tool, we demonstrate that it is possible not only to locally write and erase individual bi-solitons, reliably and reversibly, but also to track of creation yields of single and multiple bi-solitons. Bi-solitons are pairs of solitons that are elementary out-of-phase excitations on anti-ferromagnetically ordered pseudo-spin system of Si dimers on Si(001)-c(42) surfaces. We found that at low energy tunneling the single bisoliton creation mechanism is not correlated with the number of carriers tunneling, but with the production of a potential hole under the tip. An electric field at the surface determines the density of the local charge density under the tip, and band-bending. However a rapid, dynamic change of a field produces a potential hole that can be filled by energetic carriers, and the amount of energy released during filling process is responsible for the creation of bi-solitons. Our model based on the field-induced local hole gives excellent explanation for bi-soliton yield behaviors. Scanning tunneling spectroscopy data supports the existence of such a potential hole. The mechanism also explains the site-dependency of bi-soliton yields, which is highest at the trough, not on the dimer rows. Our study demonstrates that we can manipulate not just single atoms and molecules, but also single pseudo-spin excitations as well.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.1043-1050
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• 2014

An air-core vortex is generated during draining after stirring a rotating cylindrical tank or after filling it with water. The formation of the air-core vortex and the time of its formation are dependent on drain conditions such as the dimensions of the tank, the initial rotation or stirring speed, and the shape of the drain port. In this study, a draining process using a two-stage drain port was numerically investigated. The length and radius of the first drain stage located in the lower part of the drain port were kept constant, whereas the radius of the second drain stage was varied for simulating the draining process. The simulation was conducted by considering an axisymmetric swirling flow for all cases. The declining water level was monitored by an interface capturing method. Further, the effects of the radius of the second drain stage on the time of formation of the air-core vortex and the internal flow structure were investigated.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.515-524
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• 1998

The purposes of this study were to observe the cavity wall morphology and to evaluate the degree of cavity cleanliness when root-end retrograde cavity preparation was done with ultrasonic diamond instruments. To observe the morphology of retrocavity and to evaluate the degree of cavity cleanliness. root-end resections were done on 20 palatal roots of extracted maxillary first molars after canal filling with gutta-percha. Retrocavities were prepared using either ultrasonic diamond instruments or stainless steel ones of medium power setting of level 6 ($Miniendo^{TM}$, EIE, CA, U.S.A.). Morphology of the cavity. degrees of the remaining canal debris and smear layer were evaluated under the scanning electron microscope. The results were as follows: Cavities prepared with ultrasonic diamond instruments showed scratched appearance of wall, while ultrasonic stainless steel preparation showed hatcheted appearance. Ultrasonic diamond instruments induced more smear layer than stainless steel ones did (p<0.01) in the cavity. However, there was no significant difference in canal debris (p>0.05).

• Journal of the Korea Society of Computer and Information
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• v.24 no.9
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• pp.83-95
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• 2019

Recently, a variety of IoT data is collected by attaching geosensors to many vehicles that are on the road. IoT data basically has time and space information and is composed of various data such as temperature, humidity, fine dust, Co2, etc. Although a certain sensor data can be retrieved using time, latitude and longitude, which are keys to the IoT data, advanced search engines for IoT data to handle high-level user queries are still limited. There is also a problem with searching large amounts of IoT data without generating indexes, which wastes a great deal of time through sequential scans. In this paper, we propose a unified spatial index model that handles both grid and trajectory queries using a cell-based space-filling curve method. also it presents a visualization method that helps user grasp intuitively. The Trajectory query is to aggregate the traffic of the trajectory cells passed by taxi on the road searched by the user. The grid query is to find the cells on the road searched by the user and to aggregate the fine dust. Based on the generated spatial index, the user interface quickly summarizes the trajectory and grid queries for specific road and all roads, and proposes a Web-based prototype system that can be analyzed intuitively through road and heat map visualization.

• Advances in concrete construction
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• v.7 no.2
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• pp.87-96
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• 2019

Self-compacting concretes (SCC) are highly fluid concrete which can flow without any vibration. Their composition requires a large quantity of fines to limit the risk of bleeding and segregation. The use of crushed sand rich in limestone fines could be an adequate solution for both economic and environmental reasons. This paper investigates the influence of quarry limestone fines from manufactured crushed sand on rheological, mechanical and durability properties of SCC. For this purpose, five mixtures of SCC with different limestone fines content as substitution of crushed sand (0, 5, 10, 15 and 20%) were prepared at constant water-to-cement ratio of 0.40 and $490kg/m^3$ of cement content. Fresh SCC mixtures were tested by slump flow test, V-funnel flow time test, L-box height ratio, segregation resistance and rheological test using a rheometer. Compressive and flexural strengths of SCC mixtures were evaluated at 28 days. Regarding durability properties, total porosity, capillary water absorption and chloride-ion migration were studied at 180 days. For the two test modes in fresh state, the results indicated compatibility between slump flow/yield stress (${\tau}_0$) and V-funnel flow time/plastic viscosity (${\mu}$). Increasing the substitution level of limestone fines in SCC mixtures, contributes to the decrease of the slump flow and the yield stress. All SCC mixtures investigated achieved adequate filling, adequate passing ability and exhibit no segregation. Moreover, the inclusion of limestone fines as crushed sand substitution reduces the capillary water absorption, chloride-ion migration and consequently enhances the durability performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.1020-1042
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• 2019

Reversible data hiding in encrypted images (RDHEI) provides some real-time cloud applications; i.e. the cloud, acting as a data-hider, automatically embeds timestamp in the encrypted image uploaded by a content owner. Many existing methods of RDHEI only satisfy user privacy in which the data-hider does not know the original image, but leaks owner privacy in which the receiver can obtains the original image by decryption and extraction. In the literature, the method of Zhang et al. is the one providing weak content-owner privacy in which the content-owner and data-hider have to share a data-hiding key. In this paper, we take care of the stronger notion, called strong content-owner privacy, and achieve it by presenting a new reversible data hiding in encrypted images. In the proposed method, image decryption and message extraction are separately controlled by different types of keys, and thus such functionalities are decoupled to solve the privacy problem. At the technique level, the original image is segmented along a Hilbert filling curve. To keep image privacy, segments are transformed into an encrypted image by using random permutation. The encrypted image does not reveal significant information about the original one. Data embedment can be realized by using pixel histogram-style hiding, since this property, can be preserved before or after encryption. The proposed method is a modular method to compile some specific reversible data hiding to those in encrypted image with content owner privacy. Finally, our experimental results show that the image quality is 50.85dB when the averaged payload is 0.12bpp.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.4
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• pp.11-18
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• 2021

Purpose : The purpose of this study was to investigate the effect on lung capacity of healthy men and women in their twenties by performing an intervention using the chest extension exercise and the bridge exercise, which are respiratory muscle strengthening exercises. Methods : Thirty adult men and women in their 20s participated in this study. All subjects participated in the study after hearing the explanation of the purpose and method of the study, filling out a consent form. All subjects were randomly assigned to the chest extension exercise (CEE) group and the bridge exercise (BE) group of fifteen each. Each exercise was performed twice a week for 4 weeks. Lung capacity was measured by forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁) using spirometry. Lung capacity was measured before and after exercise. The measured data were compared through the dependent t-test and the independent t-test. The statistical significance level was set at .05. Results : After the intervention, the CEE group showed a significant increase in FVC and FEV₁ compared to before the intervention (p<.05). After the intervention, the BE group also had a significant increase in FVC and FEV₁ compared to before the intervention (p<.05). However, there was no difference in FVC and FEV₁ between groups before and after the intervention (p>.05). Conclusion : There was no difference between groups in lung capacity after exercise. However, both the chest extension exercise and the bridge exercise increased FVC and FEV1, which was thought to be because both exercise methods were effective in increasing lung capacity. Therefore, both chest extension exercises and bridge exercises can be effectively applied as a way to increase lung capacity.

• Korean Journal of Remote Sensing
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• v.38 no.1
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• pp.83-101
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• 2022

Accurate atmospheric correction is essential for the analysis of land surface and environmental monitoring. Aerosol optical depth (AOD) information is particularly important in atmospheric correction because the radiation attenuation by Mie scattering makes the differences between the radiation calculated at the satellite sensor and the radiation measured at the land surface. Thus, it is necessary to use high-quality AOD data for an appropriate atmospheric correction of high-resolution satellite images. In this study, we examined the Second Simulation of a Satellite Signal in the Solar Spectrum (6S)-based atmospheric correction results for the Sentinel-2 images in South Korea using raster AOD (MODIS) and single-point AOD (AERONET). The 6S result was overall agreed with the Sentinel-2 level 2 data. Moreover, using raster AOD showed better performance than using single-point AOD. The atmospheric correction using the single-point AOD yielded some inappropriate values for forest and water pixels, where as the atmospheric correction using raster AOD produced stable and natural patterns in accordance with the land cover map. Also, the Sentinel-2 normalized difference vegetation index (NDVI) after the 6S correction had similar patterns to the up scaled drone NDVI, although Sentinel-2 NDVI had relatively low values. Also, the spatial distribution of both images seemed very similar for growing and harvest seasons. Future work will be necessary to make efforts for the gap-filling of AOD data and an accurate bi-directional reflectance distribution function (BRDF) model for high-resolution atmospheric correction. These methods can help improve the land surface monitoring using the future Compact Advanced Satellite 500 in South Korea.

• International Journal of Computer Science & Network Security
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• v.22 no.8
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• pp.222-234
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• 2022

Background: Within the framework of the new Saudi Vision 2030, the education system is keen on developing Early Childhood (EC) curricula to meet the needs of children from diverse cultural and linguistic backgrounds, in addition to preparing teachers to be the main driving forces in this field. To achieve these strategic goals, the professional development of teachers has taken the lead in terms of their continuous professional achievements. Purpose: The recent study tended to explore the promotion of Cultural and Linguistic Competence (CLC) of teachers in preschool institutions in different sectors in the Kingdom of Saudi Arabia (KSA) include public, private and international. Method: In the current study, (n=300) of preschool female teachers, who had experience teaching children from diverse language and cultural backgrounds, participated voluntarily by filling out the exploratory questionnaire. It was designed on a five-point Likert scale. The credibility of the scale and the validity of the questionnaire were ascertained, and the content for which it was designed verified in terms of the purposes of the current investigation. Results: The results revealed that preschool female teachers in the private preschool settings have a higher level of CLC compared to those who were teaching in public and international preschools in KSA. In the private sector, preschool female teachers showed create abilities to provide culturally responsive environments for diverse students, applying various communication styles, and showing proper attitudes and values toward diversity. Implication: The current study provided key implications for policy makers regarding the promotion of CLC for all teachers, particularly preschool in government settings in KSA. It contributed to revealing the cultural awareness of preschool teachers' values and attitudes toward diversity.

• Journal of Dental Anesthesia and Pain Medicine
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• v.23 no.1
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• pp.1-8
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• 2023

Backgrounds: Pain management is one of the most important factors affecting the success of pediatric dentistry. Therefore, new needle- and pain-free local anesthesia techniques have been developed in parallel with technological advancements. The purpose of this study is to compare the pain perception and dental anxiety levels associated with a needle-free injection system (Comfort-in^TM) and the classic needle method during treatment-required infiltration anesthesia in children. Methods: This randomized controlled crossover split-mouth clinical study included 94 children who required dental treatment with local anesthesia using a dental needle or needle-free injection system for the bilateral primary molars. The Wong-Baker Scale (WBS) was used to measure pain perception at different times, and the Modified Child Dental Anxiety Scale (MCDAS) was used to measure the anxiety level of the child. A statistical software package was used to process the data. Statistical significance was set at P < 0.05. Results: There was no significant difference between the needle-free injection system and dental needle method during the induction stage for filling and pulpotomy (P > 0.05). "Pain on postoperative 1st day" was similar in both types of anesthesia (P = 0.750). Conclusions: The needle-free injection system was as effective as the dental needle method. The Comfort-in^TM system was an acceptable alternative for patients during the postoperative period. Understanding how pain management may be provided during local anesthesia administration and a child's fear and anxiety regarding the dentist may lead to better dental compliance.