• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.2
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• pp.180-187
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• 2022

The aim of this study was to investigate the risk factors associated with sleep disordered breathing (SDB) by comparing intraoral factors, body mass index (BMI), and medical history with pediatric sleep questionnaire (PSQ) findings. Seven hundred eighty-seven subjects aged between 7 to 11 years old were included. Their caregivers were asked to complete questionnaires. Oral manifestations including Angle's classification, overjet, and Brodsky tonsil grade were examined. Children with PSQ scores of more than 0.33 points were classified into the SDB high-risk group. Among the 787 subjects, 34 (4.3%) were classified into the SDB high-risk group. Children with allergic rhinitis, atopic dermatitis, excessive overjet, or large tonsil size had a significantly higher risk for SDB versus those without. Also, there was a significant difference in SDB risk according to BMI status. Gender, gestational age, breastfeeding, and Angle's classification were not associated with SDB. Children at high risk for SDB were predisposed to tonsillar hypertrophy, allergic rhinitis, obesity, and atopic dermatitis. Children with these factors could be candidates for early intervention to prevent the progression of SDB.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.2
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• pp.188-196
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• 2022

The purpose of this study was to investigate pediatric emergency department visits patterns and characteristics of children and adolescents under the age of 20 in South Korea from 2002 to 2015 due to dental conditions. This study used a stratified sample of approximately 1 million people from the Health Insurance Review and Assessment Service Database. The age, region, household income, and treatment cost were included for the patient characteristic analysis. Pediatric patients were compared to the adult group (over 20 years old). In children and adolescents, the rate of emergency department visits due to dental conditions was higher for traumatic conditions than for non-traumatic conditions. Children and adolescents with higher household income visited the emergency department more often than those with lower household income. The region with the highest number of children and adolescents visiting the emergency department for dental conditions was Busan (per 100,000 population). Although this study could not confirm the annual trend of children and adolescents' dental emergency visits due to the sample size limitation, the characteristics of children and adolescents' dental emergency visits were compared with those of adults using a stratified sample.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.60-67
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• 2022

An Electro-Optical Tracking System (EOTS) is an electric optical system with EO/IR cameras, laser sensors, and an IMU. The EOTS calculates coordinates of targets, using attitude and acceleration measured by the IMU. In particular for an armed aircraft, the performance of the weapon system depends on how quickly and accurately it acquires the target coordinates. The IMU should be operated after alignment is complete, to meet the coordinate accuracy required by the weapon system so the initial stabilization time of the IMU should be reduced, by quickly measuring the attitude and acceleration. Alignment is the process of determining the initial attitude by resolving the attitude error of the IMU, and the IMU of mission equipment such as an airborne EOTS, uses velocity matching based on the velocity from GPS/INS for aircraft navigation. In this paper, a method is presented to improve the transfer alignment performance of the airborne EOTS, by maneuvering aircraft and the mission equipment. First, the performance factor of the alignment was identified, as a heading error through the velocity matching model and simulation results. Then acceleration maneuvers and attitude changes were necessary, to correct the error. As a result of flight tests applied to an EOTS on a OOO aircraft system, the transfer alignment performance was improved as the duration time was decreased, by more than five times when the aircraft accelerated by more than 0.2g and the EOTS was moving until 6.7deg/s.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.4
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• pp.16-30
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• 2023

As the concept of metaverse has received great attention, interest in metaverse related to landscape architecture is also increasing. The aim of this research is to understand the potential and tasks of applying metaverse in the field of landscape architecture by analyzing the user experience of a metaverse platform. The object of the research is Meta-Everland built in the Roblox platform, which has the most users among landscape architectural metaverses in Korea. NPS of 30 users who have been to Everalnd was investigated after using Meta-Everland with interviews. NPS before the metaverse experience was -16 and NPS after the experience was -24. This result means that the promotion level was lowered after the experience of the metaverse. There were three causes of lowered NPS: lack of users, low-quality graphics and interface, and lack of content. The factor of lack of users was the result of the other two problems. The factor of low technical quality is hard to be improved in a short period of time. Therefore, the main task to improve the metaverse is developing better metaverse content related to landscape architecture. It is more appropriate to develop metaverse-specific content rather than improve reality issues. Applying AR and VR devices, enhancing communication function, and developing potential as a simulation device are needed to be considered.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.2
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• pp.155-167
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• 2023

The aim of this study was to investigate the effects of slow maxillary expansion (SME) on the dentoalveolar, skeletal, upper airway, and maxillary sinus using cone-beam computed tomography (CBCT). Twenty-three orthodontic patients (mean age 8.93 ± 1.61 years) who were treated with maxillary expansion using banded hyrax in the Department of Pediatric Dentistry at Jeonbuk National University Dental Hospital were included. According to the expansion speed applied, they were divided into two groups: SME (12 subjects, mean age 8.92 ± 1.45 years) and rapid maxillary expansion (RME, 11 subjects, mean age 8.94 ± 1.84 years). CBCT were obtained before (T0) and after (T1) the treatment and were analyzed with InVivo5 software (Anatomage, San Jose, CA, USA). Descriptive statistics showed no significant differences between the two groups in age, sex, or skeletal maturity. There were significant increases in maxillary width at the dentoalveolar and skeletal levels for both groups. Upper airway volume revealed a significant increase of 38.59% in the SME group and 28.72% in the RME group. However, there was no significant difference between SME group and RME group in all measurements. This study suggested the efficacy of SME in growing patients. SME was effective in increasing not only dentoalveolar and skeletal measurements but also airway volume. Therefore, pediatric dentists should select an appropriate expansion method considering the physiological aspects of periodontal tissues and discomfort in growing children.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.3
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• pp.252-262
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• 2023

The aim of this study was to evaluate the effectiveness of clinical trainings in improving empathy in dental students by analyzing changes in empathy level before and after clinical training. Third grade dental students at Jeonbuk National University (JBNU) participated for 2 years. They had clinical training for 3 weeks in pediatric dentistry at JBNU Dental Hospital. Then, 20 items of the modified form of Jefferson Scale of Empathy-Health Profession Students Version were done twice, before and after clinical training. The students who had lectures and role-playing were in the experimental group, while those who had no additional trainings were in the control group. Out of 69 students, 35 were in the experimental group and 34 were in the control group. Empathy level has increased after clinical training in both groups, but only the experimental group showed a significant increase (p = 0.0052). It also showed a significant increase in specific items (No. 6, 9, 10, 15, 17, 18, 19, 20) compared to the control group (p < 0.05). Clinical trainings such as lectures and role playing might have increased empathy levels related to standing in patient's position. Therefore, it is necessary to consider, try, and evaluate various types of clinical training rather than common education to improve dental students' empathy.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.2
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• pp.229-238
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• 2023

The objective of this study was to investigate trends in ankyloglossia and its surgical treatment among pediatric patients in South Korea from 2011 to 2020. Data from Health Insurance Review and Assessment Service (HIRA)'s Healthcare Bigdata Hub were used for analysis of the ankyloglossia diagnosis rate and frenum surgery rate. Considering annual population change, crude rates per 100,000 were calculated and analyzed. To investigate other factors of frenum surgery incidence besides gender and age, pediatric patient sample data from HIRA were used. The diagnosis rate of ankyloglossia increased from 204.4 in 2011 to 356.6 per 100,000 people in 2020, while the frenum surgery rate increased from 26.8 to 34.3 per 100,000 people. Males were more likely to receive frenum surgery than females. Surgeries were more likely to be done at a hospital instead of a clinic or a general hospital. In the age group of 0 - 4 years, the largest number of frenum surgeries were performed in pediatrics, and in the age group of 5 - 9 years, the largest number of surgeries were conducted in pediatric dentistry. In the older age groups, the largest proportion of frenum surgeries were performed in the departments of conservative dentistry and oral and maxillofacial surgery. The diagnosis of ankyloglossia and the operation of frenum surgery among South Korean children increased during the last decade. Since the function of the tongue can affect maxillofacial development in many aspects, pediatric dentists should pay more attention to the functional management of intraoral soft tissue in growing children.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.77-84
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• 2008

The existing equations for radial consolidation cannot account for the changes of well resistance with time and cannot predict the appropriate in-situ consolidation curve. In this study, small cylinder cell tests are performed to evaluate the discharge capacity of PVD. Also, a block sample of 1.2 m in diameter and 2.0 m in height was consolidated to observe the change in the drainage capacity with time for three types of PVD. From the test results on a block sample, the drainage curves normalized with initial drainage of each PVD are similar, regardless of the PVD type and the consolidation curve, which is predicted using solutions of radial consolidation based on the discharge capacity measured in a small cylinder cell tests, significantly overestimates the degree of consolidation. The term of well resistance in the radial consolidation solution was back-calculated to fit the consolidation curve of a large block sample and it is defined as the time dependent well resistance factor, L(t). The L(t) was found to be linearly proportional to the dimensionless time factor, Th. It was also shown that the consolidation curve evaluated by using L(t) provides more accurate prediction than the existing solution.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.77-88
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• 2006

In this study, the lateral behavior of Pile-Bent structures subjected to lateral loading was evaluated by a load-transfer approach. An analytical method based on the Beam-Column model and nonlinear load transfer curve method was proposed to consider material non-linearity (elastic and yielding) and $P-{\Delta}$ effect. Special attention was given to the lateral deflection of Pile-Bent structures depending on different soil properties, lateral load, slenderness ratio based on pier length and reinforcing effect of casing. From the results of the parametric study, it is shown that the increase of lateral displacement in a pile is much less favorable for an inelastic analysis than for an elastic analysis. It is found that for inelastic analysis, the maximum bending moment is located within a depth approximately 3.5D(D: pile diameter) below ground surface, but within 1.5D when $P-{\Delta}$ effect is considered. It is also found that the magnitude and distribution of the lateral deflections and bending moments on a pile are highly influenced by the inelastic analysis and $P-{\Delta}$ effect, let alone soil properties around an embedded pile.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.65-73
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• 2006

Reliability between safety factor and reliability index for driven and bored pile load capacity was analyzed in this study. 0.1B, Chin, De Beer, and Davisson's methods were used for determining pile load capacity by using load-settlement curve from pile load test. Each method defines ultimate yield and allowable pile load capacities. LCPC method using CPT results was performed for comparing results of pile load test. Based on FOSM analysis using load factors, it is obtained that reliability indices for ultimate pile load capacity were higher than those of yield and allowable condition. Present safety factor 2 for yield and allowable load capacities is not enough to satisfy target reliability index $2.0{\sim}2.5$. However, it is sufficient for ultimate pile load capacity using safety factor 3.