• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.61-68
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• 2010

In order to let the humanoid robot walk on the uneven terrains, the robot's foot should have the similar structure and function as human's. The intelligent foot should be made up of toes and heel. When it walks on the uneven terrains, the foot's sole senses the force and adjusts foot's position before robot losing his balance. In this paper, the force sensors of robot's intelligent foot for having the similar structure and function like human are developed. The heel 3-axis force/moment sensor and toe force sensors for humanoid robot's intelligent foot is developed, and the characteristic tests of them are carried out. As a result of characteristic test, the interference error of the heel 3-axis force/moment sensor is less than 2.2%. It is thought that the developed force sensors could be used to measure the reaction forces which is applied the toes and the heel of a humanoid robot.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.03a
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• pp.145-153
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• 2002

A coastwise chemical tanker sailing at full speed has capsized in calm water and whole turing. In the precious paper, we investigated reasons of the accident by demonstrating the proper correction for the free surface effect of the liquid cargo and the bow-sinkage effect. In this paper, we also carry out model experiments of a transverse pressure under the seawater and an outward heel moment according to the heel angle and rudder angle, on the basis of radius of turning circle, ship's speed and drift angle of model ship occurring in turning. It is also shown that the flooding of seawater onto the deck occurring in turning generated a significant outward heel moment and the vertical distance between the center of gravity of the ship and the renter of lateral water drag.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.4
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• pp.206-216
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• 2013

The present study considers the prediction of wind-induced heel of cruise ship and its stabilization. Wind load in ocean exerts on the surface of superstructure of cruise ship, which causes the heel moment on the ship. The calculation of wind load starts from choosing wind speed profile, so that the logarithmic wind profile model is applied in this study. Heel moment by wind load is calculated by adopting approximate formulation and applied to the ship motion analysis in time domain. Motion stabilizers, such as stabilizing fin and U-tube tank, are considered to reduce the heel effect as well as excessive roll motion. From this study, it is expected that the present method can be applied to the prediction and stabilization of the heel motion of cruise ships.

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.465-471
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• 2003

A coastwise chemical tanker sailing at full speed has capsized during turning in calm water. In the previous paper, we investigated the reasons of the accident by demonstrating the proper correction for the free surface effect of the liquid cargo and the bow-sinkage effect. In this paper, we also carry out model experiments of a transverse pressure under the seawater and an outward heel moment according to the heel angle and rudder angle, on the basis of radius of turning circle, ship's speed and drift angle of model ship occurring in turning. It is also shown that the flooding of seawater onto the deck occurring in turning generated a significant outward heel moment and increased the vertical distance between the center of gravity of the ship and the center of lateral water drag.

• Journal of the Ergonomics Society of Korea
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• v.35 no.1
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• pp.39-52
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• 2016

Objective: This paper investigates gait changes according to different heel heights and speeds, and the interaction between the effects of the heel height and the speed during walking on stride parameters and joint angles. Furthermore, the relationship among heel height, speed and gait variables is investigated using linear regression. Background: Gait changes by heel height or speed have been studied respectively, but has not been reported whether there is an interaction effect between heel height and speed. It would be necessary to understand how gait changes when a person wears heels in different heights at various speeds, for example, high-heeled walking at fast speed, since it may cause unusual gait patterns and musculoskeletal disorders. Method: Ten females were asked to walk at five fixed cadences (94, 106, 118, 130 and 142 steps/min.) wearing three shoes with different heel heights (1, 5.4 and 9.8cm). Nineteen gait variables were analyzed for stride parameters and joint angles using two-way repeated measure analysis of variance and regression analysis. Results: Both heel height and speed affect movement of ankle, knee, spine and elbow joint, as well as stride length and Double/Single support time ratio. However, there is no significant interaction effect between heel height and speed. The regression result shows linear relationships of gait variables with heel height and speed. Conclusion: Heel height and speed independently affect stride parameters and joint angles without a significant interaction, so the gait variables are linearly amplified or diminished by the two factors. Application: Walking in high heels at fast speed should be careful for musculoskeletal disorders, since the amplified movement of knee and spine joint can lead to increased moment. Also, the result might give insight for animators or engineers to generate walking motion with high heels at various speeds.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.13-18
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• 2015

Characteristics of restoring force for the wind-powered leisure boat was investigated using mathematical formulation and commercial computational method such as the ANSYS Workbench CFX-Mesh. The objective is to find the restoring moment and heel moment while boat is sailing in windy power. Conditions for angle of attack were given from $5^{\circ}$ to $90^{\circ}$. It is known that side force is larger in terms of angle of attack is higher, however critical angle is suggested to limit before over of $60^{\circ}$ for safe navigation for boat in wind. Natural results are found that stronger heel moment is observed when sail is used than no sail, and higher angle of attack is induced stronger heel moment.

• Korean Journal of Applied Biomechanics
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• v.23 no.3
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• pp.225-233
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• 2013

The purpose of this study was to estimate the potential injury via analyzing ground reaction force components that were resulted from a prolonged-run-induced fatigue. For the present study, passive and active components of the vertical ground reaction force were determined from time and frequency domain. Shear components of GRF also were calculated from time and frequency domain. Twenty subjects with rear foot contact aged 20 to 30, no experience in injuries of the extremities, were requested to run on the instrumented tread-mill for 160 minutes at their preference running speed. GRF signals for 10 strides were collected at 5, 35, 65, 95, 125, and 155 minute during running. In conclusions, there were no significant difference in the magnitude of passive force, impact load rate, frequency of the passive and active components in vertical GRF between running times except the magnitude of active force (p<.05). The magnitude of active force was significantly decreased after 125 minute run. The magnitude of maximum peak and maximum frequency of the mediolateral GRF at heel strike and toe-off have not been changed with increasing running time. The time up to the maximum peak of the anteroposterior at heel-strike moment tend to decrease (p<.05), but the maximum peak and frequency of that at heel and toe-off moment didn't depend significantly on running time.

• Physical Therapy Korea
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• v.6 no.2
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• pp.32-42
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• 1999

This study was conducted to identify the effects of high-heel shoes on EMG activities of rectus femoris and biceps femoris in 28 healthy women. Subjects were composed of experimental group (wearing high-heel shoes) and control group (wearing low-heel shoes). Two groups participated in three conditions standing (bare foot wearing athletic shoes and 7.5 cm height shoes). In high-heel shoes condition, EMG activities of rectus femoris of control group were significantly lower than that of biceps femoris of experimental group, but EMG activities of both muscles of experimental group did not should significant difference. In bare foot standing condition, EMG activities of rectus femoris of experimental group were significantly lower than that of biceps femoris but EMG activities of both muscles of control group had no significant difference. These results showed that hamstring lengthening effects was produced when wearing high-heel shoes because the external knee extension moment was increased. In the short term, high-heel shoes effect on the increase of the biceps femoris activities by spindle reflex, but in the long term, the normal amplitude of the same muscle activities by Golgi tendon organ reflex.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.479-486
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• 2010

The purpose of this study was to determine the effects of high-heeled shoe on the quiet standing and gait balance. Twenty women (mean height: $161.6{\pm}3.3\;cm$, mean body mass: $53.8{\pm}6.3\;kg$, mean age: $23.8{\pm}2.7$ yrs..) who were without history or complain of lower limb pain took part in this study. They were asked to stand quietly on a force platform for 30 sec and walk on it at their preferred walking speed (mean speed $3.14{\pm}0.5\;km/hr$.) with wearing three different high-heeled shoe, 3, 7, 9 cm high for collecting data. Data were randomly recorded to collect two trials for quiet standing and five trials for walking The parameters to have been analyzed for comparison between three conditions of the height of high-heeled shoe were COP(Center of Pressure) range, COP velocity, sway area, and free moment on the static balance and COP range, COP velocity, and free moment on the dynamic balance. In this study, high-heel height affected on the COP range and velocity in the ante-posterior direction during walking, dynamic balance, but didn't affect on the quiet standing, static balance.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.2
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• pp.209-217
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• 2016

Unlike conventional airplane, a WIG craft experiences righting moment and adverse yaw moment in banked turning in ground effect. Numerical simulations are carried out to study the aerodynamics of banked wing in ground effect. Configurations of rectangular wing and delta wing are considered, and performance of endplates and ailerons during banking are also studied. The study shows that righting moment increase nonlinearly with heeling angle, and endplates enhance the righting. The asymmetric aerodynamic distribution along span of wing with heeling angle introduces adverse yaw moment. Heeling in ground effect with small ground clearance increases the vertical aerodynamic force and makes WIG craft climb. Deflections of ailerons introduce lift decrease and a light pitching motion. Delta wing shows advantage in banked turning for smaller righting moment and adverse yaw moment during banking.