• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.18 no.1
• /
• pp.15-22
• /
• 1985

The study on computation time, accuracy, and convergency characteristic of the implicit finite difference method is presented with the variation of the space increment and time step in a two-dimensional transient heat conduction problem with a dirichlet boundary condition. Numerical analysis were conducted by the model having the conditions of the solution domain from 0 to 3m, thermal diffusivity of 1.26 $m^2/h$, initial condition of 272 K, and boundary condition of 255.4 K. The results obtained are summarized as follows : 1) The degree of influence with respect to the accuracy of the time step and space increment in the alternating-direction implicit method and Crank-Nicholson implicit method were relatively small, but in case of the fully implicit method showed opposite tendency. 2) To prescribe near the zero for the space increment and tine step in a two dimensional transient problem were good in a accuracy aspect but unreasonable in a computational time aspect. 3) The reasonable condition of the space increment and the time step considering accuracy and computation time could be generalized with the Fourier modulus increment, F, ana dimensionless space increment, X, irrespective of the solution domain.

• International Journal of Concrete Structures and Materials
• /
• v.9 no.4
• /
• pp.487-498
• /
• 2015

A proper initial curing is a very simple and inexpensive alternative to improve concrete cover quality and accordingly extend the service life of reinforced concrete structures exposed to aggressive species. A current study investigates the effect of wet curing duration on chloride penetration in plain and blended cement concretes which subjected to tidal exposure condition in south of Iran for 5 years. The results show that wet curing extension preserves concrete against high rate of chloride penetration at early ages and decreases the difference between initial and long-term diffusion coefficients due to improvement of concrete cover quality. But, as the length of exposure period to marine environment increased the effects of initial wet curing became less pronounced. Furthermore, a relationship is developed between wet curing time and diffusion coefficient at early ages and the effect of curing length on time-to-corrosion initiation of concrete is addressed.

• The Korean Journal of Emergency Medical Services
• /
• v.24 no.2
• /
• pp.99-109
• /
• 2020

Purpose: Alcohol intoxication is frequently observed in patients with brain hemorrhage. The purpose of this study was to determine whether intoxication affects the Korean Triage and Acuity Stage (KTAS) level and the emergency medical process in emergency departments. Methods: This study was a retrospective observational study enrolled 253 brain hemorrhage patients (47 of those intoxicated) who visited the emergency medical center on public EMS ambulance from January. 1, 2017 to April, 30, 2019. Data were collected through the electronic medical record (EMR). KTAS level and time to computerized tomography (CT) were compared to evaluate whether inebriation affects care and examination processes. All data were analyzed using SPSS program. Results: Of the 47 patients intoxicated patients, 85.1% were male, and 74.5% accompanied by trauma. Initial KTAS level showed significant differences (77.2%; p=.000) when the level 3,4 was not drunk. The average time taken from triage to CT scans showed a significant difference of 24.81±23.72 (min) when the drunken state was not 58.38±56.54 (min)(p=.000). Conclusion: In patients with brain hemorrhage admitted to ED from public EMS, undertriage and delay after initial assessment were detected in inebriated patients. Careful initial evaluation and prompt medical response should be considered for patients transported by EMS.

• Journal of Internet Computing and Services
• /
• v.21 no.4
• /
• pp.77-85
• /
• 2020

The purpose of this study is to explore the changing trajectory of using educational media through longitudinal data analysis. We categorize the feature of using educational media as usage for learning, usage for information, and usage for the game. We explore the longitudinal changing patterns of usage for learning, usage for information, and usage for the game by LGM(Longitudinal Growth Modeling). We also find the gender difference between these longitudinal changing trajectories. We used 3,499 samples of KYPS middle school second-grade panel data. We found these results: (a) Both usage for learning and information are statically significant variability in initial level and rate of change. Both of the changing trajectories have increased. (b) Girls have a higher rate of the change both in the usage of learning and information than boys over time. (c) There is a statistically significant individual variability in initial levels and rate of change in the usage of the game over time. (d) Boys have a higher rate of initial value than girls in the usage of games, but there is no significant difference in the rate of changing trajectories.

• Journal of Oral Medicine and Pain
• /
• v.46 no.2
• /
• pp.41-48
• /
• 2021

Purpose: To evaluate compliance by analyzing and comparing treatment duration, degree of improvement after treatment and treatment response of oral lichen planus (OLP) patients according to characteristics of them and the severity of the lesion. Methods: According to treatment process, 132 subjects with OLP who first visited the Department of Oral Medicine at the Pusan National University Dental Hospital from January 2017 to December 2020were classified into three groups: Treatment completed (CT) group, Under treatment (UT) group, and Dropped out during follow-up (DT) group. The reticulation/keratosis, erythema, and ulceration (REU) scoring system was used to assess the severity of OLP. The degree of improvement after treatment was evaluated in CT group. Results: There were 53 (40.15%) CT, 27 (20.45%) UT and 52 (39.39%) DT. In CT group, according to initial REU score there was a statistical difference in the degree of improvement, but not in the length of time to complete treatment. There was no statistical difference between the days it took for patients to feel symptom relief, and the days of entire treatment among three groups. However, there was a positive correlation between the REU score of gingiva and duration of treatment in DT group. In the CT and DT groups, there was a correlation between the length of time taken to relieve symptoms and the duration of treatment. Conclusions: The severity of the gingival lesion and the initial response to treatment have a large effect on the entire treatment period and prognosis, so it should be considered when explaining the disease prognosis and treatment period to patients, and the clinician needs to focus on initial symptom relief.

• Journal of applied mathematics & informatics
• /
• v.40 no.3_4
• /
• pp.409-431
• /
• 2022

In this paper, we deal with the existence of solutions of the following system of nonlinear rational difference equations with order five $x_{n+1}=\frac{y_{n-3}x_{n-4}}{y_n(a+by_{n-3}x_{n-4})}$, $y_{n+1}=\frac{x_{n-3}y_{n-4}}{x_n(c+dx_{n-3}y_{n-4})}$, n = 0, 1, ⋯, where parameters a, b, c and d are not executed at the same time and initial conditions x_-4, x_-3, x_-2, x_-1, x₀, y_-4, y_-3, y_-2, y_-1 and y₀ are non zero real numbers.

• Steel and Composite Structures
• /
• v.18 no.6
• /
• pp.1465-1478
• /
• 2015

The effect of cutting off fibers on transient load in a polymeric matrix composite lamina was studied in this paper. The behavior of fibers was considered to be linear elastic and the matrix behavior was considered to be linear viscoelastic. To model the viscoelastic behavior of matrix, a three parameter solid model was employed. To conduct this research, finite difference method was used. The governing equations were obtained using Shear-lag theory and were solved using boundary and initial conditions before and after the development of break. Using finite difference method, the governing integro-differential equations were developed and normal stress in the fibers is obtained. Particular attention is paid the dynamic overshoot resulting when the fibers are suddenly broken. Results show that considering viscoelastic properties of matrix causes a decrease in dynamic load concentration factor and an increase in static load concentration factor. Also with increases the number of broken fibers, trend of increasing load concentration factor decreases gradually. Furthermore, the overshoot of load in fibers adjacent to the break in a polymeric matrix with high transient time is lower than a matrix with lower transient time, but the load concentration factor in the matrix with high transient time is lower.

• International Journal of Contents
• /
• v.10 no.3
• /
• pp.9-16
• /
• 2014

Depth-image-based rendering is generally used in real-time 2D-to-3D conversion for 3DTV. However, inaccurate depth maps cause flickering issues between image frames in a video sequence, resulting in eye fatigue while viewing 3DTV. To resolve this flickering issue, we propose a new 2D-to-3D conversion scheme based on fast and robust depth-map generation from a 2D video sequence. The proposed depth-map generation algorithm divides an input video sequence into several cuts using a color histogram. The initial depth of each cut is assigned based on a hypothesized depth-gradient model. The initial depth map of the current frame is refined using color and motion information. Thereafter, the depth map of the next frame is updated using the difference image to reduce depth flickering. The experimental results confirm that the proposed scheme performs real-time 2D-to-3D conversions effectively and reduces human eye fatigue.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.55 no.10
• /
• pp.452-457
• /
• 2006

In this paper, an algorithm to detect steps in hemiplegic patients using a 3-axis accelerometer a紅ached on the trunk was proposed. The proposed algorithm consisted of the signal pre-processing, the step detector, the classification of steps and the calculation of stride time. Two FIR band-pass filters were designed and steps were measured by the combination of filtered signals in the vertical and the anteroposterior directions. In addition, the classification of steps and the calculation of stride time were computed by using the detected steps and lateral signals. For the experiment, fourteen hemiplegic patients were participated and the linear accelerations of the trunk and foot switch signals were measured synchronously. To evaluate the system performance, the detected steps and initial contacts by the foot switch were compared. The average error between the steps and initial contacts was 0.024ms and the difference of the average stride time was 0.01s. Finally, all gait events were detected exactly. Results showed that the accelerometry could use for the gait evaluation in clinical rehabilitation therapies.

• Phonetics and Speech Sciences
• /
• v.7 no.4
• /
• pp.139-145
• /
• 2015

The present study investigates the effects of syllable structure and prosodic prominence on the patterns of tonal alignment and scaling of the phrase-initial rise in Seoul Korean. Two syllable structures (Onset (/#CVC.../ as in minsa) vs. No-onset (/#VC.../ as in insa)) and two prominence conditions (Focus vs. Neutral) were considered. Results showed that the alignment of the L and the H tones in the phrase-initial rise was affected by syllable structure but not by prominence. The time of L was before the vowel onset of the first syllable in the Onset condition (i.e., within the onset consonant) and it was after the vowel onset in the No-onset condition. The difference was attributable to the fact that the initial L was anchored at a fixed distance from the phrase boundary, which was about 30ms after the onset of the syllable in both cases. The time of H was also consistently observed about 20ms after the second vowel onset (i.e., /a/ in minsa/insa). Moreover, the rise time (the duration from the L to the H tones) was longer as the local syllable duration became longer due to different syllable structure and prominence conditions. Taken together, the results provide a support for the segmental anchoring hypothesis, which claims that both the beginning and the end of F0 movement are consistently aligned with segmental 'anchor' points with relatively high stability (Ladd et al., 1999). Results also showed that the scaling of the early rise was slightly influenced by syllable structure but not by prominence. The differences between the results of the current study and a previous study (Cho, 2011) are further discussed.