• Elastomers and Composites
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• v.58 no.3
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• pp.112-120
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• 2023

Herein, we propose a facile water-processible method to develop an eggshell membrane (ESM)-embedded waterborne polyurethane (WPU)-based bio-degradable and bio-compatible coating material that exhibits attractive tactile properties. Virgin ESM is not dispersible in water. Hence, to develop the ESM-based WPU composite, soluble ESM (S-ESM) was first extracted by de-crosslinking the ESM. The extracted S-ESM at different concentrations (0, 0.5, 1.0, 1.5 wt %) was mixed with WPU. Compared to virgin WPU, the viscosity of S-ESM/WPU dispersion and the in-plane coefficient of friction (COF) of the composite film surfaces decreased with an increase in the S-ESM content. In addition, an increase in the S-ESM content improved the tribo-positive characteristics of the film. Different good touch-feeling biomaterials, such as fur, feather, and human skin exhibit tribo-positivity. Thus, the enhanced tribo-positive characteristics of the S-ESM/WPU and the decrease in their COF owing to an increase in the S-ESM content imply the enhancement of its touch-feeling performance. The S-ESM embedded WPU composites have potential applications as coating materials in various fields, including automobile interiors and artificial leather.

• Journal of the Korean Geotechnical Society
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• v.34 no.3
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• pp.67-75
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• 2018

In this study, we developed a micropile equipped with ground fixing wedge device which is able to ensure the bearing capacity early before grouting by expanding the tip and exerting the tip surface friction while compressing and expanding the tip of the micropile during loading. The purpose of this study is to verify the applicability of the developed micropile to the ground with various kinds of strength and to compare its characteristics with those of the simple tip expansion micropile. A new test system including a model soil box which can measure the tip resistance and the tip skin friction separately was devised. The loading test was carried out according to the changes of the ground strength and the tip cross section using the devised test systems. As a result of the test, it was found that the developed micropile increased the tip skin friction due to the wedge horizontal force as the soil strength increased and could be applied more effectively to the ground with the strength not lower than the strength of the weathered rock. In addition, it was found that additional bearing capacity could be obtained due to the tip cross section expansion and the wedge horizontal force exertion even in the ground with the strength below the weathered rock strength.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.1-6
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• 2020

This study is about the safe arm posture in case of emergency escape using the vertical dive rescue sack at the fire site. The experimental results are as follows. First, the arms extended upward contact with the endothelium and narrowing part of the rescue sack minimized the scratches did not occur. Second, the bent position with both arms open was subject to light abrasions of on the elbows due to friction between the elbows and the scapula and the endothelium. Third, in the posture where both arms were gathered in the chest, the body passed through the narrowing part and friction between the bag's narrowing part, All subjects had light abrasions on their elbows. Fourth, because the arms are lowered, the legs are extended to the width of the shoulders when descending, so that the back of the hand has friction with the narrowing part of the bag and the endothelial skin. Finally, posture with both arms below the front increased the volume of the front of the body, resulting in a slight back injury. As a future research task, it is necessary to study the proper posture of legs and the posture of landing on the ground.

• Archives of design research
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• v.20
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• pp.211-217
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• 1997

Natural dyes don't pollute the environments in contrast to artifical dyes. The cloths dyed with natural material can be developed into insect-proof clothing and bedding. With natural tint, they can also produce natural images. The purpose of this paper is to show the way to develop the natural dye material easily available at cheap cost, to produce high value added products in terms of dyeing a wide range of colors by using this material, and to suggest the way for farmers to cultivate the onions in their idle land, thus gaining additidnal income. In the process of dyeing natural cloth with onion skin produced largely in Mooan, Chonnam, we were able to extract a wide spectrum of colours from yellow to pale brown and gray. Having reaped good results in the various endurance tests(of washing, friction, water, sweat, sunlight), this material is estimated to be highly worthy of industrialization.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.1
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• pp.71-81
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• 2017

In this study, a series of full-scale extrapolation procedures based on the Granville's similarity scaling method, which was employed by Schultz (2007), is modified and then applied to compare the resistance performance between two different anti-fouling coatings. As an analysis example, the low frictional AF coating based on a novel skin-friction reducing polymer named FDR-SPC (Frictional Drag Reduction Self-Polishing Copolymer), which had been invented by the present author, is employed. The low frictional coating, which gives 25.4% skin frictional reduction in lab test, is estimated to give 18.2% total resistance reduction for a 176k DWT bulk carrier.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1287-1294
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• 2006

A pile is compressed with settlements when loading and bearing capacity is altered along relative displacement of pile/soil on settlement and compression. Settlements of pile displaying limit skin friction is different from displaying tip resistance. Therefore, it is an error in traditional method that bearing capacity of pile is estimated from the sum of limit skin fraction and tip resistance. Accordingly, development of design method considering behavior of load-settlement is needed. In this study, we would like to establish the base for development of design method considering bearing capacity altering along displacement on settlement and compression. For this, we established system and substance of design method. And in order to establish relationship of load-settlement of pile on the type of soil, we analyzed and arranged existing database and pile loading test. On design method, settlement is assumed gradually on each capacity level being assumed gradually. Bearing capacity developing on the pile is obtained on each settlement level. Until the obtained bearing capacity will be equal to assumed capacity, this process is continued with increasing settlement. Load-settlement curve for soil classification is sketched in the process computing settlement on assumed capacity. This design method will be materialized by computation program.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.5
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• pp.685-694
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• 2002

Effects of wake-passing orientation and frequency on the wake-induced boundary layer transition on a NACA0012 airfoil are investigated. The wakes are generated by rotating cylinders clockwise (CW) and counterclockwise (CCW) around the airfoil. Time- and phase-averaged streamwise mean velocities and turbulent fluctuations are measured with a single hot-wire probe. Wall skin frictions are estimated by the Computational Preston Tube Method (CPM). The pressure distribution on the airfoil is different according to the wake-passing orientation and frequency. Turbulent patches are generated in the laminar boundary layer due to the passing wake and the boundary layer becomes temporarily transitional. The transition process is significantly affected by the pressure gradient and the turbulent patches. For the receding wake, the turbulent patches propagate more rapidly than those for the approaching wake because adverse pressure gradient becomes larger. As the frequency increases, onset location of transition moles upstream and the boundary layer near the trailing edge becomes more transitional.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.776-785
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• 2001

Hot-wire measurements are performed in boundary layers developing on a NACA0012 airfoil over which wakes pass periodically. The Reynolds number based on chord length of the airfoil is 2$\times$10(sup)5 and the wakes are generated by circular cylinders rotating clockwise and counterclockwise around the airfoil. This paper and its companion Part II describe the phenomena of wake-induced transition of the boundary layers on the airfoil using measured data; phase-and time-averaged streamwise mean velocities, turbulent fluctuations, integral parameters and wall skin frictions. This paper describes the background and facility together with results of time-averaged quantities. Due to the passing wake with mean velocity defects and high turbulence intensities, the laminar boundary layer is periodically disturbed at the upstream station and becomes steady-state transitional boundary layer at the downstream station. The velocity defect in the passing wake changes the local pressure at the leading of the airfoil, significantly affects the time-mean pressure distribution on the airfoil and eventually, has influence on the transition process of the boundary layer.

• Tribology and Lubricants
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• v.26 no.3
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• pp.184-189
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• 2010

In this paper, tactile response characteristics in medical haptic interface are investigated to characterize the feeling of contact between the finger skin and the organic tissue when a finger is dragged over tissue. In order to represent the tactile feeling, a prototype tactile display incorporating Magneto-Rheological (MR) fluid has been developed. Tactile display devices simulate the finger's skin to feel the sensations of contact such as compliance, curvature and friction. Thus, the tactile display provides the surface information of organic tissue to the surgeon using different actuating mechanisms ranging from the conventional mechanical motor to the smart material actuators. In order to investigate the compliance feeling of human finger's touch, vertical force responses of the tactile display under the various magnetic fields have been assessed. Also, frictional resistive force responses of the tactile display are investigated to simulate the action of finger's dragging. From the results, different tactile feelings are observed as the applied magnetic field is varied and arrayed magnetic poles combinations. This research gives a smart technology of tactile displaying.

• Fashion & Textile Research Journal
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• v.17 no.6
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• pp.1039-1049
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• 2015

The increase in the need for a 24 hour monitoring of biological signals has been accompanied by an increasing interest in wearable systems that can register ECG at any time and place. ECG-monitoring clothing is a wearable system that records heart function continuously, but there have been difficulties in making accurate measurements due to motion artifacts. Although various factors may cause noise in measurements due to motion, the variations in the body surface and clothing during movements that cause eventual the shifting and displacement of the electrodes is particularly noteworthy. Therefore, this study used biomedical body mapping and a motion-capture system to measure and analyze the changes in the body surface and garment during movements. It was deduced that the area where the friction and separation between the garment and skin is the lowest would be the appropriate location to place the ECG electrodes. For this study, 5 male and 5 female in their 20s were selected as subjects, and through their selected body movements, the changes in the garment and skin were analyzed using the motion-capture system. As a result, the area below the chest circumference and the area below the shoulder blades were proposed as the optimal location of electrode for ECG monitoring.