• Physical Therapy Rehabilitation Science
• /
• v.7 no.2
• /
• pp.61-66
• /
• 2018

Objective: Patellofemoral pain syndrome (PFPS) is a condition that is characterized by patellar discomfort or pain that is aggravated during certain activities such as ascending/descending stairs. The Patellofemoral Disability Index (PDI) was developed to assess the effect of pain on functional activities in individuals with PFPS. The objectives of the current study were to determine the internal consistency, test-retest reliability, and validity of this index. Design: Cross-sectional study. Methods: Forty-one subjects who had PFPS with a mean age of $28.8{\pm}5.0years$ and a mean body mass index of $25.6{\pm}4.7kg/m^2$ participated in the study. All subjects were concurrently enrolled in a clinical trial for which they were instructed to complete hamstring-resistance exercises for 4 weeks. Over the course of the intervention, they completed both the PDI and the Oswestry Disability Index (ODI) at baseline after two weeks, and after four weeks. Pearson correlation coefficient was used to assess the criterion validity. Cronbach's ${\alpha}$ was used to examine the internal consistency. Intraclass correlation coefficients with 95% confidence interval were computed to examine test-retest reliability. Results: Subjects' responses within both the PDI and the ODI yielded Pearson correlation coefficient values that were positive and highly significant (range, 0.73-0.97; p<0.001). There was a high level of internal consistency (Cronbach's ${\alpha}{\geq}0.8$), with the exception of stair climbing (Cronbach's ${\alpha}=0.65$). Intraclass correlation ranged from 0.87 to 0.92, indicating high levels of test-retest reliability. Conclusions: The PDI is a valid, reliable, and feasible method of assessing pain and functional ability in patients with PFPS.

• Structural Engineering and Mechanics
• /
• v.60 no.6
• /
• pp.939-952
• /
• 2016

A compression to tensile load transforming (CTT) device was developed to determine indirect tensile strength of concrete material. Before CTT test, Particle flow code was used for the determination of the standard dimension of physical samples. Four numerical models with different dimensions were made and were subjected to tensile loading. The geometry of the model with ideal failure pattern was selected for physical sample preparation. A concrete slab with dimensions of $15{\times}19{\times}6cm$ and a hole at its center was prepared and subjected to tensile loading using this special loading device. The ratio of hole diameter to sample width was 0.5. The samples were made from a mixture of water, fine sand and cement with a ratio of 1-0.5-1, respectively. A 30-ton hydraulic jack with a load cell applied compressive loading to CTT with the compressive pressure rate of 0.02 MPa per second. The compressive loading was converted to tensile stress on the sample because of the overall test design. A numerical modeling was also done to analyze the effect of the hole diameter on stress concentrations of the hole side along its horizontal axis to provide a suitable criterion for determining the real tensile strength of concrete. Concurrent with indirect tensile test, the Brazilian test was performed to compare the results from two methods and also to perform numerical calibration. The numerical modeling shows that the models have tensile failure in the sides of the hole along the horizontal axis before any failure under shear loading. Also the stress concentration at the edge of the hole was 1.4 times more than the applied stress registered by the machine. Experimental Results showed that, the indirect tensile strength was clearly lower than the Brazilian test strength.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.6
• /
• pp.419-426
• /
• 2018

Recently, in an effort to reduce the energy efficiency design index (EEDI), studies on energy saving devices (ESDs) have been conducted. In this study, we designed a post-device suitable for a KRISO container ship (KCS) using computational fluid dynamics (CFD). In order to increase the efficiency of the post-device, a twisted rudder was used, which has a proven performance (showing a 1.34% reduction in DHP compared to the bare hull at 24 knots) in previous research at Pusan National University. In addition, an increase in efficiency was expected by the use of a rudder bulb, including the discontinuous section of the twisted rudder and a divergent propeller cap to prevent the contraction of the wake. The optimization criterion was the case where the delivery power was the least compared with the bare hull. We analyzed the cause of the efficiency increase through an analysis of the self-propulsion factor. The case study for optimization was divided into 4 types (1. clearance of the bulb and cap, 2. shape of the bulb, 3. size of the bulb and cap, and 4. asymmetric bulb). Finally, with a clearance of 50 mm from the ship, a spherical bulb with the cap having an angle of $5^{\circ}$, and an asymmetric rudder bulb with a bulb diameter of 1.2HH/1.4H (horizontal/vertical) showed a 2.05% reduction in DHP compared to the bare hull at 24 knots. We will fabricate a post-device that will be optimized in the future and verify the performance of the post-device through model tests.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.6
• /
• pp.251-258
• /
• 2018

Recently, due to the increase in the traffic volume of vehicle, the collision of the vehicle collision has been increased so that the neck injuries of the passengers has been increased. In order to prevent this, vehicle collision analysis research using computer simulation has been actively carried out in consideration of the design point of car seat. In this study, I used the MADYMO program for analyzing the passenger behavior using a BioRID II dummy, and predicted the neck injuries of passengers according to the change of the backset at the rearward collision of the driving speed of 16km/h. As a result, it was found that the shorter the backset, the shorter the contact start time but the contact completion time was almost the same and the T1 acceleration showed that the acceleration increased with the backset. In addition, the tensile strength increases as the backset increases, and NIC (Neck Injury Criterion) increases as the head speed reaches the headrest.

• The Journal of Korean Society for School & Community Health Education
• /
• v.19 no.3
• /
• pp.1-14
• /
• 2018

Objectives: The purpose of this study was to investigate the prevalence of metabolic syndrome and to find related factors according to the number of metabolic syndrome diagnostic components in Korean adolescents. Methods: The subjects of this study were 469 Korean adolescents aged from 12 to 18 enrolled in the 2016 Korea National Health and Nutrition Examination Survey. Statistical package R 3.4.2 was used for programming to apply diagnostic criterion of adolescent metabolic syndrome and for the analysis of the data such as weighted frequent analysis, weighted mean analysis and complex sampling design logistic regression analysis. Results: For adolescents 12 to 18 years of age, 2.55% had more than 2(${\geq_-}3$), 9.88% had more than 1(${\geq_-}2$) and 33.17% had more than 0(${\geq_-}1$) metabolic syndrome diagnostic components. It has been found that risk factors for no less than 2 metabolic syndrome diagnostic components were higher body mass index and higher stress, and risk factors for no less than 1 were higher body mass index, younger teenager and female. Conclusion: Obesity is the primary risk factor for the development of adolescent metabolic syndrome. Female or younger teenager are more likely to have one or more metabolic syndrome diagnostic components, and higher stress develop to the risk level of having two or more metabolic syndrome diagnostic components. Therefore, it is important to focus on obesity and stress management for the prevention and control of Korean adolescent metabolic syndrome.

• Journal of Practical Engineering Education
• /
• v.10 no.1
• /
• pp.57-62
• /
• 2018

The recognition of the importance of lifelong vocational competency development, the proliferation of MOOC, and interest in online education have increased. As a result, efforts are continuously being made to develop an education system for lifelong vocational competency development. However, research on design and development of competency-based evaluation tools and systems in the field of technology engineering is still insufficient. In this paper, we designed and implemented a Competency-based Assessment System for Lifelong Vocational Competency Development(CBAS-LVCD). CBAS-LVCD utilizes NCS-based rubric-based assessment tools to evaluate learners and provides simulation tools for use in technology engineering. This is expected to be of great help in assessing the competencies required for practical affairs in the field of technology engineering, where practical work and on-line testing are limited.

• Journal of the Korean Geotechnical Society
• /
• v.35 no.2
• /
• pp.5-17
• /
• 2019

Dynamic centrifuge model test was conducted to evaluate the dynamic stability of the pile-supported slab track method during dynamic railway loading and earthquake loading. The centrifuge tests were carried out for various condition of embankment height and soft ground depth. Based on test results, we found that the bending moment was increased with embankment height and decreased with soft ground depth. In addition, it was confirmed that the pile-supported slab track system could have dynamic stability for short-period seismic loading. However, in case of long-period seismic loading, such as Hachinohe earthquake, the observed maximum bending moment reached to pile cracking moment at the return period of 2,400 year earthquake. The criterion of ratio between embankment height and soft ground depth was suggested for dynamic stability of pile-supported slab track system.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.4
• /
• pp.643-652
• /
• 2021

Accidents or faults in the transmission and distribution system are never completely avoidable, and short-circuit and earth faults are occurs despite the efforts of the TSO and DSO. Recently, the connection to the transmission and distribution system of large-capacity new and renewable distributed power has increased rapidly and has various effects on the operation of the system. In order to minimize this, connection standards such as FRT (Fault-Ride-Through) have been established to provide wind turbines or solar inverters. In the event of a major faults of the power system, the operation support shall be provided so that the operator can stably operate the system by smoothly performing connection maintenance or rapid system separation. In this paper, in order to appropriately determine whether the FRT condition, which is the grid connection criterion for a representative DERs, is sufficient, a detection system using a PMU (Phasor Measurement Unit) that measures a synchro-phasors was designed and deployment and a system accident due to a generator step-out to analyze and evaluate the proposed system based on the case.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.63 no.2
• /
• pp.75-84
• /
• 2021

As the weather changes become frequent, weather disasters are increasing, causing more damage to plastic greenhouses. Among the damage caused by various disasters, damage by snow to the greenhouse takes a relatively long time, so if an alarm system is properly prepared, the damage can be reduced. Existing greenhouse design standards and snow warning systems are based on snow depth. However, even in the same depth, the load on the greenhouse varies depending on meteorological characteristics and snow density. Therefore, this study aims to secure the structural safety of greenhouses by developing sensors that can directly measure snow loads, and analysing the warning criteria for load using a stochastic model. Markov chain was applied to estimate the failure probability of various types of greenhouses in various regions, which let users actively cope with heavy snowfall by selecting an appropriate time to respond. Although it was hard to predict the precise snow depth or amounts, it could successfully assess the risk of structures by directly detecting the snow load using the developed sensor.

• Women's Health Nursing
• /
• v.27 no.4
• /
• pp.307-317
• /
• 2021

Purpose: The purpose of this study was to develop and test the validity and reliability of the Korean version of the Perinatal Infant Care Social Support (K-PICSS) for postpartum mothers. Methods: This study used a cross-sectional design. The K-PICSS was developed through forward-backward translation. Online survey data were collected from 284 Korean mothers with infants 1-2 months of age. The 19-item K-PICSS consists of functional and structural domains. The functional domain of social support measures infant care practices of postpartum mothers. Exploratory factor analysis (EFA) and known-group comparison were used to verify the construct validity of the K-PICSS. Social support and postpartum depression were also measured to test criterion validity. Psychometric testing was not applicable to the structural social support domain. Results: The average age of mothers was 32.76±3.34 years, and they had been married for 38.45±29.48 months. Construct validity was supported by the results of EFA, which confirmed a three-factor structure of the scale (informational support, supporting presence, and practical support). Significant correlations of the K-PICSS with social support (r=.71, p<.001) and depression (r=-.40, p<.001) were found. The K-PICSS showed reliable internal consistency, with Cronbach's α values of .90 overall and .82-.83 in the three subscales. The vast majority of respondents reported that their husband or their parents were their main sources of support for infant care. Conclusion: This study demonstrates that the K-PICSS has satisfactory construct validity and reliability to measure infant care social support in Korea.