• Journal of Digital Convergence
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• v.11 no.11
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• pp.521-528
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• 2013

This study was performed to examine effects of PNF combined pattern training on balance ability and functional ability of hockey players. In order to achieve this purpose, total 28 participants were separated into two group: 14 comparison group and 14 experiment group, and the experiment group performed PNF combined pattern training for 12 week, 3 times a week, 60 minutes a day. Each group was measured beforehand, after 6 week and 12 week. balance ability was measured using GOOD BALANCE system and functional ability was measured using carioca and shuttle-run test. For statistically verifying above measured values, repeated measure analysis of variance was analyzed and have following results. As the comparing results of balance ability, normal standing eye close(NSEC) was ant-post and velocity moment of experiment group showed significant differences(p<.05). And one leg right eye close(OLREC) was ant-post, med-lat and velocity moment of experiment group showed significant differences (p<.05). Also, dynamic balance ability was ant-post and velocity moment of experiment groups showed significant differences(p<.05). As the comparing results of functional ability, shuttle-run of experiment group sowed significant differences(p<.05). From above results, balance ability of hockey players was shown to be improved through symmetric training of PNF combined pattern applied to hockey players, and it can be considered that this is actively recommended for training method to improve athletic performance of hockey players.

• Journal of Digital Convergence
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• v.11 no.7
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• pp.281-288
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• 2013

The purpose of this study was to identify the effects of upper and lower limb coordinated exercise for gait ability in stroke patients. Upper and lower limb coordinated exercise method was conducted in two different groups; one is an one leg support group and the other is a non support group. In this study, 14 patients were participated. One leg support group was applied to 7 patients, and non support group was applied to 7 patients. Both group carried out 3 times a week for 30 minutes during 4 weeks. Data were analyzed statistically via Repeated two-way ANOVA, Mann-Whitney U test, and Friedman test. The results of the measurement analysis were summarized as follows: 1. There were significant differences in 10MWT among 2 groups after intervention(p<.05). 2. There were significant differences in F8WT, FSST among 2 groups after intervention(p<.05). According to Bonferroni test, one leg support group had significant increased from pre-intervention to post-4 week. However, there were no significant differences in nonsupport group. In conclusion, improvement of gait ability in chronic stroke patients was effect to upper and lower limb coordinated exercise.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.619-629
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• 2013

The objective of this study is to estimate shear wave velocity of earth dam materials using artificially generated vibration from blasting events and to verify its applicability. In this study, the artificial blasting and vibration monitoring were carried out at the site adjacent to Seongdeok dam, which is the first blasting test for an existing dam in Korea. The vibrations were induced by 4 different types of blasting with various depths of blasting boreholes and explosive charge weights. During the tests, the acceleration time histories were recorded at the bedrock adjacent to the explosion and the crest of the dam. From frequency analyses of acceleration histories measured at the crest, the fundamental frequency of the target dam could be evaluated. Numerical analyses varying shear moduli of earth fill zone were carried out using the acceleration histories measured at the bedrock as input ground motions. From the comparison between the fundamental frequencies calculated by numerical analyses and measured records, the shear wave velocities with depth, which are closely related to shear moduli, could be determined. It is found that the effect of different blasting types on shear wave velocity estimation for the target dam materials is negligible and the shear wave velocity can be consistently evaluated. Furthermore, comparing the shear wave velocity with the previous researchers' empirical relationships, the applicability of suggested method is verified. Therefore, in case that the earthquake record is not available, the shear wave velocity of earth dam materials can be reasonably evaluated if blasting vibration test is allowed at the site adjacent to the dam.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.489-494
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• 2015

This research focused on minimizing the response of fixed cylindrical offshore structures to a ship impact considering the seawater fluid part. A collision between a ship and offshore structure is generally a complex problem and it is often impractical to perform rigorous finite element analyses to include all the effects and sequences during the collision. The structural behavior of a fixed cylindrical type offshore substructure with a seawater fluid part has a simpler response and small deformation due to the dissipation of impact energy. Upon applying the impact force of a ship to the cylindrical structure, the maximum acceleration, internal energy, and plastic strain are calculated for each load cases using Ls-dyna finite element software. In the maximum cases 2.0 m/s velocity, the response result for the structure was carried out to compare between having a fluid region and no fluid region. Fluid-structure interaction analysis was performed using the ALE method, which make it possible to apply a fluid region on the impact problem. The case of a fixed cylindrical type offshore structure without a seawater fluid part can be a more conservative design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.369-374
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• 2015

This study analyzed analyzes the energy performance of six houses in Daejeon completed which were built in 2011. Observed The observed houses, which were all designed and constructed inof the same size and structure, are were highly insulated with triple Low-E coating windows; the insulation level of the walls is was $0.13W/m^2K$ and that of the roof is was $0.10W/m^2K$. As electric houses, all of the energy supplied to the houses, including for cooking, is was supplied by electricity. A and 3~4 kWp of photovoltaic system and a 3~5 kW of ground source heat pump (GSHP) were installed in each house tofor providing provide space heating/and cooling and hot water are installed. We constructed a Web-based remote monitoring system in order to understand energy consumption and the dynamic behavior of the energy system. T, and the results of our metering data analysis of 2013 are as follows. First, the annual residential energy consumption is was 4,400 kWh (${\sigma}=1,209$) and GSHP energy consumption is was 5,182 kWh (${\sigma}=1,164$). Second, residential energy consumption ranked highest in average energy usage, with at 45% of the total, followed by heating with at 30%, hot water supply with at 17% and cooling with at 6%. Third, the average energy independence rate is was 51.8%, the GFA (Gross gross floor area) criteria average energy consumption unit is was $48.7kWh/m^2yr$ (${\sigma}=10.1$), and the net energy consumption unit (except the energy yield of the PV systems) is was $24.7kWh/m^2yr$ (${\sigma}=8.8$).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.4
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• pp.177-190
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• 2016

In case of the seabed around and under gravity structures such as submerged breakwater is exposed to a large wave action long period, the excess pore pressure will be generated significantly due to pore volume change associated with rearrangement soil grains. This effect will lead a seabed liquefaction around and under structures as a result from decrease in the effective stress. Under the seabed liquefaction occurred and developed, the possibility of structure failure will be increased eventually. Lee et al.(2016) studied for regular waves, and this study considered for irregular waves with the same numerical analysis method used for regular waves. Under the condition of the irregular wave field, the time and spatial series of the deformation of submerged breakwater, the pore water pressure (oscillatory and residual components) and pore water pressure ratio in the seabed were estimated and their results were compared with those of the regular wave field to evaluate the liquefaction potential on the seabed quantitatively. Although present results are based on a limited number of numerical simulations, one of the study's most important findings is that a more safe design can be obtainable when analyzing case with a regular wave condition corresponding to a significant wave of irregular wave.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.3 s.55
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• pp.87-96
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• 2007

A new Energy-Dissipating Sacrificial Device (EDSD) is developed for steel plate girders, which can effectively dissipate the energy stored in the structures during seismic actions. To verify the performance of the EDSD, various seismic responses of a sample bridge with the EDSD are analyzed in terms of energy, member forces and deformation. The full scale model tests are conducted to certify the performance of the EDSD when it is applied on existing bridges. Using the improved hysteretic model of the sacrificial member, the seismic analysis for an example bridge is performed. The results show that the proposed EDSD under seismic excitations can significantly decrease the energy stored in the bridge structures and reduce the relative displacements of each superstructure to the ground. The EDSD is also found to function as a structural fuse under strong ground motions, sacrificing itself to absorb the excessive energy. Consequently, economical enhancement of the seismic performance of bridges can be achieved by employing the newly developed energy-dissipating sacrificial device.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.343-349
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• 2013

Crashworthy fuel cells have a great influence on improving the survivability of crews. Since 1960's, the US army has developed a detailed military specification, MIL-DTL-27422, defining the performance requirements for rotorcraft fuel cells. In the qualification tests required by MIL-DTL-27422, the crash impact test should be conducted to verify the crashworthiness of fuel cell. Success of the crash impact test means the improvement of survivability of crews by preventing post-crash fire. But, there is a big risk of failure due to huge external load in the crash impact test. Because the crash impact test itself takes a long-term preparation efforts together with costly fuel cell specimens, the failure of crash impact test can result in serious delay of a entire rotorcraft development. Thus, the numerical simulations of the crash impact test has been required at the early design stage to minimize the possibility of trial-and-error with full-scale fuel cells. Present study performs the numerical simulation using SPH(smoothed particle hydro-dynamic) method supported by a crash simulation software, LS-DYNA. Test condition of MIL-DTL-27422 is reflected on analysis and material data is acquired by specimen test of fuel cell material. As a result, the resulting equivalent stresses of fuel cell itself are calculated and vulnerable areas are also evaluated.

• Management & Information Systems Review
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• v.36 no.5
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• pp.85-98
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• 2017

The purpose of this study is to exploratory examine the structural relationships among meaningfulness of work, personality(Big 5 character-types) and job stress. To conduct such examination, the author (i) designated meaningfulness of work, personality(Big 5 character-types) and job stress as variables and (ii) designed a research model by conducting preceding studies on the variables. To examine the research model the author collected the survey data from the residents in Kyoungsangbuk-do, 332 copies of questionnaire. Collected data were analyzed using SPSS and AMOS programs. The analysis results are as follows. Especially, (1) the meaningfulness of work had a positive effect on agreeableness, conscientiousness, and extraversion. (2) the meaningfulness of work had a negative effect on neuroticism. (3) the meaningfulness of work had no effect on openness to experience. (4) the neuroticism factor had a positive effect on psychological job stress and physical job stress. (5) the openness to experience had a negative effect on psychological job stress and physical job stress. (6) the meaningfulness of work had no effect on psychological job stress and physical job stress. The implications and limitation which this study are as follows. First, this study has discovered that there was statistically significant relationship between the meaningfulness of work and Big 5 character-types. Second, Big 5 character-types(neuroticism, openness to experience) had statistically effect on psychological job stress and physical job stress. This study have limitation in that was conducted based on cross-sectional design of research. Because, the mechanism of job stress is a dynamic process.

• The Journal of the Acoustical Society of Korea
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• v.37 no.2
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• pp.99-109
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• 2018

The precision of the vibration-sensors, contact or non-contact types, is usually satisfactory for the practical measurement applications, but a sensor is confined to the measurement of a point or a direction. Although the precision and frequency span of the low-cost camera are inferior to these sensors, it has the merits in the cost and in the capability of simultaneous measurement of a large vibrating area. Furthermore, a camera can measure multi-degrees-of-freedom of a vibrating object simultaneously. In this study, the calibration method and the dynamic characteristics of the low-cost machine vision camera as a sensor are studied with a demonstrating example of the two-dimensional vibration of a cantilever beam. The planar image of the camera shot reveals two rectilinear and one rotational motion. The rectilinear vibration motion of a single point is first measured using a camera and the camera is experimentally calibrated by calculating error referencing the LDV (Laser Doppler Vibrometer) measurement. Then, by measuring the motion of multiple points at once, the rotational vibration motion and the whole vibration motion of the cantilever beam are measured. The whole vibration motion of the cantilever beam is analyzed both in time and frequency domain.