• Journal of the Society of Naval Architects of Korea
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• v.45 no.2
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• pp.109-123
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• 2008

The present paper presents the CFD result for a beam wave test case. An ONR tumblehome ship model with bilge keels is used. The beam wave test is for zero forward speed and roll and heave 2DOF with wave slope $a_k=0.156$ and wavelength ${\lambda}=1.12L_{PP}$, with $L_{PP}$ the ship length. The problems is solved numerically with an unsteady Reynolds averaged Navier-Stokes approach. The free surface flow is computed using a single-phase level-set method and the motions in each time step are integrated using a predictor-corrector iteration approach which uses dynamic overset grids moving with relative ship motion. The predicted CFD results for motions and forces are compared with experimental data, showing a reasonable agreement.

• The Journal of Korean Physical Therapy
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• v.31 no.4
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• pp.193-198
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• 2019

Purpose: This study examined the effects of plank exercise combined with breathing and arm exercises on the external oblique, internal oblique, and transverse abdominal muscle thickness. Methods: Thirty healthy adults consisting of 12 males and 18 females from K area were divided into a plank exercise combined with breathing and arm exercises group (n = 15) and a plank exercise only group (n=15). The changes in muscle thickness before the exercise and four and eight weeks after the exercise were analyzed using a two-way repeated analysis of variance (ANOVA). The significance level was set to ${\alpha}=0.05$. Post-hoc t-tests were conducted to detect the interactions between the time and groups, and the significance level was set to ${\alpha}=0.01$. Results: According to the experimental results, the external oblique abdominal muscle showed significant differences over time (p<0.05). The internal oblique abdominal muscle also showed significant differences over time and in the interactions between the time and groups (p<0.05). The transverse abdominal muscle showed significant differences over time, in the interactions between time and groups, and in the changes between the groups (p<0.05). Conclusion: The results indicated that plank exercise combined with breathing and arm movement exercises led to increases in the abdominal muscle thickness. These types of exercises may be useful in lumbar stabilization rehabilitation treatment.

• Journal of Korean Physical Therapy Science
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• v.30 no.3
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• pp.31-40
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• 2023

Background: The purpose of this study was to confirm the effect of bridge exercise combined with vibration on abdominal muscle thickness. Design: Randomized controlled trial. Methods: As study subjects, 24 adults in their 20s were classified into 12 vibration bridge exercise groups and 12 bridge exercise groups. The time was divided into before the experiment, 3 weeks after the experiment, and 6 weeks after the experiment. Two-way repeated ANOVA was used to examine changes in the muscle thickness of the external oblique, internal oblique, and transverse abdominal muscles of the trunk muscles, and the significance level was set at 0.05. If there was an interaction between time and group, post-hoc analysis was performed, and the significance level was set at 0.01. Results: There was a significant difference in the external oblique muscle in the change by period, the interaction between time and group, and the change between groups (p<0.05). There was a significant difference in the external oblique muscle in the change by period, the interaction between time and group, and the change between groups (p<0.05). Conclusion: As a result of this study, bridge exercise combined with vibration had a positive effect on the muscle thickness of the external oblique, internal oblique, and transversus abdominis muscles. It suggests the possibility of using the basic data of vibration exercise and the lumbar stabilization exercise in clinical practice.

• Journal of Korean Physical Therapy Science
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• v.30 no.3
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• pp.41-48
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• 2023

Background: This study examined the effects of the bridge exercise with trunk rotation on the thickness of body trunk muscles, including external oblique, internal oblique, and transverse abdominis in healthy male adults. Design: Randomized controlled trial Methods: Twenty-four men were evenly divided into a trunk rotation bridge exercise group and a basic bridge exercise group by drawing lots. The two groups performed the respective exercise for thirty minutes, three times a week for six weeks. repeated measure analysis of variance (ANOVA) was used after distinguishing between three different time points before the experiment, three weeks after the experiment, and six weeks after the experiment. The significance level was set at 0.05. In case an interaction between time and group existed, the paired t-test was used to examine the within-group difference. The independent-sample t-test was used to check the between-group difference. The significance level was set at 0.05. Results: All the men showed a significant change over time in their external oblique, internal oblique, and transverse abdominis muscles. An interaction between time and group was also found (p<0.05). Conclusion: The bridge exercise with trunk rotation causes a meaningful difference in the thickness of external oblique, internal oblique, and transverse abdominis muscles. Therefore, this study proposes the use of this exercise for lower-back stabilization in future research and clinical settings.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.51-54
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• 2003

Fluid is an effective element in computer animation. Recently, the techniques from CFD have been actively applied to CG production. In this paper, we describe our fluid animation system which implements a variety of established simulation and rendering methods. We also explain our new techniques such as chemical reaction and hardware-assisted fluid animation that are being developed to enhance the features of our software system.

• Communications for Statistical Applications and Methods
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• v.13 no.3
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• pp.719-732
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• 2006

A set of clustering algorithms with proper weight on the formulation of distance which extend to mixed numeric and multiple binary values is presented. A simple matching and Jaccard coefficients are used to measure similarity between objects for multiple binary attributes. Similarities are converted to dissimilarities between i th and j th objects. The performance of clustering algorithms with balancing weight on different similarity measures is demonstrated. Our experiments show that clustering algorithms with application of proper weight give competitive recovery level when a set of data with mixed numeric and multiple binary attributes is clustered.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.47-52
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• 1999

In this paper we propose new approximate method for the performance analysis of closed-loop production system with unreliable machines and random processing times. The approximate method decomposes the production system consisting of K machines into a set of K subsystems, each subsystem consisting of two machines separated by a finite buffer. Then, each subsystem is analyzed by analyzing method n isolation. The population constraint of the closed-loop production system is taken into account by prescribing that the sum of average buffer level in the subsystems is equal to the number of customers in the closed-loop production system,. We establish a set of equations that characterizes unknown parameters of the servers in the subsystems. An iterative procedure is then used to determine the unknown parameters. Experimental results show that these methods provide a good estimation of the throughput.

• ETRI Journal
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• v.43 no.4
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• pp.746-757
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• 2021

Side-channel attacks pose an inevitable challenge to the implementation of cryptographic algorithms, and it is important to mitigate them. This work identifies a novel data encoding technique based on 1-of-4 codes to resist differential power analysis attacks, which is the most investigated category of side-channel attacks. The four code words of the 1-of-4 codes, namely (0001, 0010, 1000, and 0100), are split into two sets: set-0 and set-1. Using a select signal, the data processed in hardware is switched between the two encoding sets alternately such that the Hamming weight and Hamming distance are equalized. As a case study, the proposed technique is validated for the NIST standard AES-128 cipher. The proposed technique resists differential power analysis performed using statistical methods, namely correlation, mutual information, difference of means, and Welch's t-test based on the Hamming weight and distance models. The experimental results show that the proposed countermeasure has an area overhead of 2.3× with no performance degradation comparatively.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.25 no.4
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• pp.224-229
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• 2014

Objectives : This study was conducted in order to investigate the influences of school violence on the mental health of student victims and their parents. Methods : A total of 56 (aged 7-18) student victims and their parents were selected to participate in a survey. The students had experienced school violence from June 2012 to October 2013. They completed a set of self-report questionnaires, including socio-demographic characteristics, family relationship, Impact of Event Scale-Revised, Child Depression Inventory (CDI), Beck Depression Inventory, Revised Children's Manifest Anxiety Scale, and Parental Bonding Instrument to evaluate psychiatric complications and to understand the emotional bonding between them. Results : The student's level of impact of event was significantly related to the parent's level of impact of event (p<.001). The student's high CDI score showed positive correlation with high level of impact of event (p<.001). In addition, higher level of the student's perceived emotional support and understandability of family showed association with lower level of impact of event (p<.01, p<.05). Conclusion : The results of this study suggest that the psychiatric sequelae of school violence is seriously affected by family support and parent's level of impact of event. Therefore, more active intervention is needed for both students and their parents.

• PNF and Movement
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• v.18 no.1
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• pp.133-141
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• 2020

Purpose: The purpose of this study was to conduct balance training through vision control to improve the balance, postural control, and balance confidence and to decrease the visual and sensory dependence of stroke patients. Methods: Twenty-eight chronic stroke patients volunteered to participate in the study. They were randomly assigned to the eyes-closed and the eyes-open training groups. Three times a week for four weeks each group performed an unstable-support session and a balance training session for thirty minutes per set. Their balance, postural control, and balance confidence were assessed using BIO Rescue (BR), the postural assessment scale for stroke (PASS), and the Korean activity-specific balance confidence scale (K-ABC), respectively. All data were analyzed using SPSS version 22.0. Statistical methods before and after working around the average value of each dataset were independent T-test. The significance level for statistical analyses was set at 0.05. Results: Comparison between the groups showed statistically significant effects on all variables before and after the intervention (p < 0.05). Conclusion: This study reflected that balance-training programs involving vision control improve the balance, postural control, and balance confidence of chronic stroke patients. Thus, stroke patients should undergo training programs that increase the use of their other senses with vision control in clinical practice.