• Korean Journal of Applied Biomechanics
• /
• v.27 no.2
• /
• pp.149-155
• /
• 2017

Objective: The purpose of this study was to investigate the effects of three visual conditions (eyes opened, eyes closed, and wearing of a head mounted display [HMD]) on single-leg standing through kinematics and kinetic analysis. Method: Twelve college students (age: $24.5{\pm}2.6years$, height: $175.0{\pm}6.4cm$, weight: $69.2{\pm}5.1kg$) participated in this study. The study method adopted three-dimensional analysis with six cameras and ground reaction force measurement with one force plate. The analysis variables were coefficient of variation (CV) of the center of body mass, head movement, ground reaction force, and center of pressure, which were analyzed using one-way analysis of variance with repeated measures according to visual conditions. Results: In most cases, the results of this study showed that the CV was significantly higher in the order of HMD wearing, eyes closed, and eyes opened conditions. Conclusion: Our results indicated that body sway was the largest in the HMD wearing condition, and the risk of falling was high owing to the low stability.

• Journal of the Korean Society of Safety
• /
• v.15 no.1
• /
• pp.126-131
• /
• 2000

This study based on the laboratory works, analyzes factors affecting local scour in order to understand various characteristics of the local scour surrounding bridge piers. Attached with scour protection device as a method for decreasing local scour, it carries out the laboratory experiments and calculates the scour depth. From the experiments attached with the scour protection devices, it seems possible to reduce the scour depth as the protecting plate, column and sacrificial piles are built in the same height with flume bed at pier or footing upstream interrupted falling-flow. And then it could reduce scour depth. The paper presents the following research results: First, the decreasing degree of scour depth is in order of protecting column, protecting plate, sacrificial piles and non-protecting facilities. However, it shows no meaningful difference between protecting column and protecting plate. Second, when $L_p/b$=0.5~1, the decreasing effect of scour depth reached the maximum of 40 percents.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2012.01a
• /
• pp.59-60
• /
• 2012

자유 낙하하는 물체가 받는 힘은 중력 뿐이다. 우리는 중력만을 받아서 운동하는 것을 자유 낙하 운동이라고 하고 자유 낙하하는 물체를 자유낙체라 한다. 다시 말해서, 물체의 초기 운동 상태와 무관하게 중력의 영향으로만 자유롭게 낙하하는 물체를 말하는 것이다. 본 논문에서는 공기의 저항을 무시하고, 수직방향으로 짧은 거리의 범위 내에서 고도에 의한 자유낙하 가속도의 변화가 없다는 가정을 하고, 자동차가 수직 상 방향으로 출발하여 도약하고 최고점에 도달하는 시간, 최대높이, 자동차가 출발 위치로 돌아오는 시간과 자동차의 속도, 자동차가 땅에 떨어질 때의 시간 및 속도에 대해 알 수 있다.

• Korean Institute of Interior Design Journal
• /
• no.18
• /
• pp.3-8
• /
• 1999

In accordance with the growing up to a fine-built national physique on national economic rapid growth, It should be made a partial amendment on the Installation planing of sanitary ware. If users who regard have no problem as using facilities in a unisex toilet, It'll be not only falling down the separation of toilet booth with substantial sanitary problems step by step as follow. 1. The urinal should be pay due regard to such a shape which intercepts stream before the point of dispersion and variations in splash effects according to angles between stream and contact urinal surface with deferent of age and health of users 2. Urinal should be fit for the perineum height of male and so It could be install differently according to the Anatomical Percentile of users.

• The Korean Journal of Food And Nutrition
• /
• v.25 no.1
• /
• pp.156-162
• /
• 2012

The purpose of this study was to investigate the effect and correlation of anthropometric data, eating behaviors, and nutrient intake on the bone mineral density(BMD) of female college students. 349 female college students were surveyed and their age, height, and weight were an average of 20.5 years, 163.2 cm and 54.0 kg, respectively. Their average BMI was 20.2, with 66% falling in the normal range, 21.8% classified as underweight, 8.0% as overweight, and obese individuals comprised 3.4% of the sample by BMI classification. Calcaneal BMD was measured and the average T-score was 0.117. The results of BMD measurements were normal in 268 people(76.8%), osteopenia was found in 71 individuals(20.3%), and osteoporosis in 10(2.9%), respectively. There was a significant difference in bone mineral density according to height(p<0.05) and BMI (p<0.01). There were significant differences between BMD and eating behavior, regularity of eating behaviors(p<0.05), instant food intake(p<0.05), eating out(p<0.05) and nutritional supplement intake(p<0.05). In addition, normal the group with normal BMD had a more desirable eating behavior compared to the osteopenia and osteoporosis afflicted groups. BMD had a significant difference according to the nutrient intake of calcium(p<0.05), vitamin A(p<0.05), and vitamin C(p<0.05). In conclusion, BMD showed a good correlation with height(p<0.01), BMI(p<0.01), body composition including total body water(p<0.05), FFM(p<0.05), body protein(p<0.05) and intake of calcium(p<0.05), iron(p<0.05), vitamin A(p<0.05), and vitamin C(p<0.05). Therefore, an education plan and training on balanced diets proper body weight control, and desirable eating behaviors for female college students will be needed.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.21 no.1
• /
• pp.54-62
• /
• 2009

The present study investigates the behaviour of overtopping flows falling on the leeside of a caisson breakwater with dissipating blocks through laboratory measurements. The falling overtopping flows in the leeside are expected to directly affect the leeside stability of the breakwater. This study focuses on not the resultant stability but the characteristic pattern of the overtopping flows depending on wave conditions through examining front velocity and plunging distance in the leeside. Regular waves were used to investigate the dependence of the overtopping flow pattern on wave conditions and a modified image velocimetry combining the shadowgraphy and cross-correlation method was employed for measurements of image and velocity. From the measurements, it is shown that the plunging distance and front velocity of the overtopping flow in the breakwater leeside increase as the wave period or height increases. From non-dimensional relationships between the variables, empirical formula for the velocity and overtopping distance are suggested.

• Journal of the Korean Society of Safety
• /
• v.35 no.4
• /
• pp.23-31
• /
• 2020

In the construction sector, there were 99 fatalities from falls associated with steel tube and system scaffolds for three years from 2016 to 2018 and out of which 27.3 percent (27 workers) were found to have occurred during installing and dismantling procedure. To erect scaffolding which is installed for the work at height, the work platforms are generally installed first and the safety guardrails are installed and vice versa to dismantle. As a result, workers are exposed to the risk of falling because they erect and dismantle scaffolding without guardrails. To minimize the risk of falling, it is necessary to study a new construction method that can erect or dismantle scaffolding while guardrails are installed (called advanced guardrail system). This study analyzed advanced guardrail system in terms of safety regulation, workability and economic efficiency by investigating the domestic situation on the use of scaffolding, reviewing domestic and foreign standards for guardrails and conducting economic feasibility study. The results of this study is expected to greatly contribute to preventing falls in scaffolding installation and dismantlement procedure. As a follow-up study, empirical research is required including physical test of scaffolding with advanced guardrail system and effectiveness analysis after trial applications.

• Geomechanics and Engineering
• /
• v.37 no.5
• /
• pp.431-441
• /
• 2024

A newly developed line-style sand pluviator has been calibrated to prepare repeatable sand specimens of specific statuses of compactness and homogeneity for laboratory tests. Sand is falling via a bottom slot of a fixed hopper, and by moving the sample container under the slot, the container is evenly filled with sand. The pluviator is designed with high flexibility: The falling height of sand, the hopper's opening width and the relative moving speed between the hopper and the sample box can be easily adjusted. By changing these control factors, sand specimens of a wide range of densities can be prepared. A series of specimen preparation was performed using the coarse Merwede River sand. Performance of the pluviator was systematically evaluated by exploring the alteration of achievable density, as well as checking the homogeneity and fabric of the prepared samples by CT scanning. It was found that the density of prepared coarse sand samples has monotonic correlations with none of the three control factors. Furthermore, CT scanning results suggested that the prepared samples exhibited excellent homogeneity in the horizontal direction but periodical alteration of density in the vertical direction. Based on these calibration test results, a preliminary hypothesis is proposed to describe the general working principles of this type of pluviators a priori, illustrating the mechanisms dominating the non-monotonic correlations between control factors and the relative density as well as the vertically prevalent heterogeneity of specimens. Accordingly, practical recommendations are made in a unified framework in order to lessen the load of similar calibration work.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.3
• /
• pp.423-429
• /
• 2018

Objective: This study was conducted to investigate the effects of WBVE on biomechanical factor analysis of drop landing jumps before and after a four week training program. Methods: Participants were divided into two group: VEG (n=5, age: $25.7{\pm}2.3yrs$, height: $170{\pm}7.6cm$, weight: $69.3{\pm}8.3kg$) and OEG (n=5, age: $24.6{\pm}3.4yrs$, height: $164{\pm}4.9cm$, weight: $58.8{\pm}9.2kg$). Ten infrared cameras (Vicon, UK) with a sampling rate of 100 Hz were used in two GRF measurement systems (AMTI, USA). Results: The variability of the center of mass was largest at the falling phase, and there was a great risk of injury when landing after the jump. Second, the jumping heights of the VEG (vibration exercise group) were higher than those of the OEG (only exercise group), regardless of training period. Third, there were significant differences in the hip joint P1 (flexion) and knee joint P2 (extension) between the exercise groups after 4 weeks of training. However, there were no significant differences among training periods or phases. Conclusion: regardless of training periods, the VEG showed increased jump height compared with the OEG, but the consistency between the jump height and the lower joint power could not be determined.

• Journal of Navigation and Port Research
• /
• v.39 no.1
• /
• pp.77-82
• /
• 2015

Slamming means that the hull hits the waves and receives impact pressure. This slamming effect may cause harm to people and when you put the hull at risk. so it is very harmful for cargo safety. Therefor slamming impact pressure should be fully considered in ship designing. In this study the model of wedged type structure are produced aimed to simulate a free fall that the experiments were carried out on different weight and free fall height. The flow field has been obtained by 2-frame grey level cross correlation PIV(Particle Image Velocimetry) method and experiment was divided into water entry and water exit. The impact pressure of free fall structure by a pressure acquisition system apply to dewetron system. The angles between a model and the water surface are adapted $15^{\circ}$ respectively. The weight change of models was given as 1.5, 1.8 and 2.0kg. To study slamming phenomenon for free fall height the experiments were carried out by the free fall height of 100, 200 and 300mm. The experimental value of the impact pressure according to the changes in weight was increase impact pressure in proportion to the increase in weight and higher free falling height has also influenced the increase in impact pressures.