• Journal of Positioning, Navigation, and Timing
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• v.9 no.4
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• pp.397-403
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• 2020

In order to synchronize a remote system time to the reference time like Coordinated Universal Time (UTC), it is required to compare the time difference between the two clocks. The time comparison data may have some outliers and the time synchronization performance can be significantly degraded if the outliers are not removed. Therefore, it is required to employ an effective outlier detection algorithm for keeping high accurate system time. In this paper, an outlier detection method is presented for the time difference data of GNSS time transfer receivers. The time difference data between the system time and the GNSS usually have slopes because the remote system clock is under free running until synchronized to the reference clock time. For investigating the outlier detection performance of the proposed algorithm, simulations are performed by using the time difference data of a GNSS time transfer receiver corrected to a free running Cesium clock with intentionally inserted outliers. From the simulation, it is investigated that the proposed algorithm can effectively detect the inserted outliers while conventional methods such as modified Z-score and adjusted boxplot cannot. Furthermore, it is also observed that the synchronization performance can be degraded to more than 15% with 20 outliers compared to that of original data without outliers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.1
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• pp.1-6
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• 2022

Recently, IoT sensors are often used to produce stream data locally and they are provided for edge computing applications. Mass-produced data are stored in the mobile device's database for real-time processing and then synchronized with the server when needed. Many mobile databases are developed to support those applications. They are CloudScape, DB2 Everyplace, ASA, PointBase Mobile, etc, and the most widely used database is SQLite3 on Linux. In this paper, we focused on the performance required for synchronization with the server. The search performance required to retrieve SQLite3 was compared and analyzed according to the type of each Linux file system in which the database is stored. Thus, performance differences were checked for each file system according to various search query types, and criteria for applying the more appropriate Linux file system according to the index use environment and table scan environment were prepared and presented.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.6
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• pp.339-347
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• 2021

Piston type wave makers or flap type wave makers are usually adopted as a wave maker which disturbing the fluid domain with sinusoidal motion. Recently hybrid wave maker which could be operated as not only piston type and/or flap type but also swing type wave maker have been devised by utilizing the link mechanism. The wave board of hybrid wave maker has been devised to be independently controlled by the horizontal actuators on upper and lower end of the wave board. The wave board could operate as a flap type wave board when the lower hinge is in a stationary condition and the upper hinge is operated with sinusoidal motion. On the contrary, the swing type wave board could be obtained by the lower hinge is activated and the upper hinge is in a stationary condition. When both end of the wave board is activated in a synchronized condition, the wave board motion become piston motion. In addition the hybrid wave maker could enhance the piston motion with flap motion or swing motion by selecting control parameters. Various wave board motion of hybrid wave maker and relevant wave form have measured on the wave board and departed location. It is appeared that the novel hybrid wave maker could be utilized for the improvement of wave qualities in experiments.

• Journal of Convergence for Information Technology
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• v.12 no.4
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• pp.67-76
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• 2022

The purpose of this study was to identify the effects of high fidelity simulation-based education for cardiac arrest emergency nursing applied to nursing students on communication self-efficacy, communication competence, and educational satisfaction. For this study a nonequivalent control group non-synchronized post-test design was used. Participants were 42 nursing students who attended in one university and completed the self-report questionnaire. Data were analyzed through frequency, percentage, mean, standard deviation, x² test, and independent t-test using the SPSS 22.0 program. As a result, communication self-efficacy (t=2.87, p=.007), communication competence (t=2.96, p=.005) and educational satisfaction (t=4.75, p=<.001) were significantly higher than in the control group after high fidelity simulation-based education. High fidelity simulation-based education for cardiac arrest emergency nursing was able to improve communication self-efficacy, communication competence, and educational satisfaction for nursing students.

• The Journal of Korean Academic Society of Nursing Education
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• v.28 no.2
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• pp.117-126
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• 2022

Purpose: This study aimed to examine the effects of an eye health education program on the level of knowledge and eye health practice of middle school students. Methods: This quasi-experimental study was conducted using a pretest-posttest nonequivalent control group non-synchronized design. The study participants were from one middle school first graders in a province of Korea. The experimental group was composed of three classes (76 students), and the control group was composed of three other classes (77 students). Pretests were conducted in June for the experimental group and in August for the control group. The experimental group received an eye health education program developed for this study consisting of four sessions in total, given once a week for 45 minutes per session. The control group was instructed by the school's health teacher in the eye health education included in the existing health education curriculum. Posttests were conducted three weeks after the training in the control group and immediately after the fourth eye health education session in the experimental group. Results: After being instructed in the eye health education program, the eye health-related knowledge (t=9.45, p<.001) and eye health practice (t=2.18, p=.031) of the experimental group participating in the education program were higher than those of the control group. Conclusion: The eye health education program was effective in improving middle school student's level of eye health-related knowledge and eye health practice. School health teachers could implement this program as a part of the standard eye health education for middle school students. The long-term effects of practicing eye health behavior needs to be confirmed in a future study.

• Wind and Structures
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• v.34 no.5
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• pp.421-435
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• 2022

To investigate the non-Gaussian properties of fluctuating wind pressures and the error margin of extreme wind loads on a long-span curved roof with matching and mismatching ratios of turbulence integral scales to depth (L_u^x/D), a series of synchronized pressure tests on the rigid model of the complex curved roof were conducted. The regions of Gaussian distribution and non-Gaussian distribution were identified by two criteria, which were based on the cumulative probabilities of higher-order statistical moments (skewness and kurtosis coefficients, S_k and K_u) and spatial correlation of fluctuating wind pressures, respectively. Then the characteristics of fluctuating wind-loads in the non-Gaussian region were analyzed in detail in order to understand the effects of turbulence integral-scale. Results showed that the fluctuating pressures with obvious negative-skewness appear in the area near the leading edge, which is categorized as the non-Gaussian region by both two identification criteria. Comparing with those in the wind field with matching L_u^x/D, the range of non-Gaussian region almost unchanged with a smaller L_u^x/D, while the non-Gaussian features become more evident, leading to higher values of S_k, Ku and peak factor. On contrary, the values of fluctuating pressures become lower in the wind field with a smaller L_u^x/D, eventually resulting in underestimation of extreme wind loads. Hence, the matching relationship of turbulence integral scale to depth should be carefully considered as estimating the extreme wind loads of long-span roof by wind tunnel tests.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.3
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• pp.245-259
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• 2023

The purpose of this paper is to examine the most recent tunnel scanning systems to obtain insights for the development of non-contact mobile inspection system. Tunnel scanning systems are mostly being developed by adapting two main technologies, namely laser scanning and image scanning systems. Laser scanning system has the advantage of accurately recreating the geometric characteristics of tunnel linings from point cloud. On the other hand, image scanning system employs computer vision to effortlessly identify damage, such as fine cracks and leaks on the tunnel lining surface. The analysis suggests that image scanning system is more suitable for detecting damage on tunnel linings. A camera-based tunnel scanning system under development should include components such as lighting, data storage, power supply, and image-capturing controller synchronized with vehicle speed.

• Journal of Korea Entertainment Industry Association
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• v.13 no.4
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• pp.63-70
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• 2019

We extract the symptom of panic disorder from the context awareness environment. It extracts body context information through natural movement that exists in everyday life and uses a component of panic disorder. The ontology theory can be used to provide information on the degree of symptoms of panic disorder through inference process. For the components of panic disorder to the information processing based on ontology are defined as Classes. Panic disorder index is expressed through ontology modeling so that the condition of panic disorder can be known. The derivation of panic disorder component and panic disorder index will enable context awareness based information service for panic disorder. The context information is periodically synchronized with the context awareness on based device. Panic disorder can be used to improve the lifestyle of panic disorder.

• Journal of Korean Clinical Nursing Research
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• v.29 no.1
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• pp.67-74
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• 2023

Purpose: This study aimed to identify the effect of warm scarf on xerostomia and sore throat in postoperative colon cancer patients. Methods: A total of 40 participants with colon cancer who underwent colon cancer operation over 2hours were included from C University hospital in Seoul. The number of experimental group and control group is each 20 calculated by G*Power, and they were assigned by using nonequivalent control group no-synchronized design. In the experimental group, a warm scarf was applied to the neck for 120 minutes from entering the recovery room after the colorectal cancer surgery was completed. In the experimental group and the control group, xerostomia and sore throat were measured twice at 60-minute intervals. The degree of xerostomia was measured through the degree of wetness of the absorbent paper in mm, and the degree of sore throat was measured through the NRS (Numeral Rating Scale). Data were collected using self-administered questionnaires from August 2018 to September 2020 and were analyzed using IBM SPSS/WIN 21.0 Descriptive statistics, x² test, Fisher's exact test, t-test were used to determine the participant's characteristics. The effect of warm scarf on xerostomia and sore throat were separately estimated by Repeated Measures ANOVA. Results: The experimental group showed significant decrease of xerostomia and sore throat as time goes (p<.001). Conclusion: Results indicate that warm scarf on xerostomia and sore throat in postoperative colon cancer patients is helpful method for relieving side effect of tracheal intubation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.2
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• pp.75-83
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• 2023

In this paper, we present the analysis results on the vibration serviceability of a pedestrian bridge considering the effect of pedestrian moving mass inertia. Using dynamic finite element analysis, we considered different walking scenarios, including pedestrian density, walking speed, random walking, and synchronized walking, to analyze the acceleration response of a 40m long single-span bridge with a steel composite box cross section. We showed that the equivalent fixed mass analysis method did not significantly differ from the moving mass analysis in the random walk scenario and a wider frequency excitation band may be useful to consider when evaluating vibration serviceability in a random walk scenario.