• Fashion & Textile Research Journal
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• v.9 no.2
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• pp.243-248
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• 2007

This study is about the fabric attached to the relics excavated from the Shimchun-ri tomb of the 4th century and the Moonsan-ri tombs of the 5th century. We studied 5 pieces of fabric from the Shimchun-ri tomb: one piece was silk and the other four pieces were hemp. We were able to observe 8 pieces from the four tombs in Moonsan-ri, All of them except one ramie were silk. The two kinds of bast fiber found in the tombs of Shimchun-ri and Moonsan-ri were hemp and ramie, and they were found to be plain woven with S-twist thread which thickness is uneven. The density was more fine compared to the hemps found in the Kaya or Shinra tombs of the similar era. All of the silk textiles found in the Shimchun-ri and Moonsan-ri tombs used non-twisted thread, and were plain woven. Also, we found degummed and raw silk from the tombs. The average density of the silk textiles from these tombs are similar to other areas of the same time, and studies show that they used non-twisted thread in plain woven silk found in other tombs. Therefore, we can conclude that they usually used non-twisted thread when producing silk textiles.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.10
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• pp.46-53
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• 2007

This paper describes the development of a high-precision measuring device with DSP (digital signal processor) for the accurate measurement of the 6-axis force/moment sensor mounted to a humanoid robot's ankle. In order to walk on uneven terrain safely, the foot should perceive the applied forces Fx, Fy, and Fz and moments Mx, My, and Mz to itself, and control the foot using the measured them. The applied forces and moments should be measured from two 6-axis force/moment sensors mounted to the feet, and the sensor is composed of Fx sensor, Fy sensor, Fz sensor, Mx sensor, My sensor and Mz sensor in a body (single block). In order to acquire output values from twelve sensors (two 6-axis force/moment sensor) accurately, the measuring device should get the function of high speed, and should be small in size. The commercialized measuring devices have the function of high speed, unfortunately, they are large in size and heavy in weight. In this paper, the high-precision measuring device for acquiring the output values from two 6-axis force/moment sensors was developed. It is composed of a DSP (150 MHz), a RAM (random access memory), amplifiers, capacities, resisters and so on. And the characteristic test was carried out.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.4
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• pp.85-92
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• 2020

Applications for the unmanned aerial vehicle (UAV) have expanded enormously in recent years. Of all its various technologies, the UAV's ability to take off and land in a moving environment is particularly required for military or oceanic usage. In this study, we develop a novel leveling platform that allows the UAV to stably take off and land even on uneven terrains or in moving environments. The leveling platform is composed of an upper pad and a lower mobile base. The upper pad, from which the UAV can take off or land, is designed in the form of a 2 degrees of freedom (DOF) gimbal mechanism that generates the leveling function. The lower mobile base has a four-wheel drive structure that can be operated remotely. We evaluate the developed leveling platform by performing extensive experiments on both the horizontal terrain and the 5-degree ramped terrain, and confirm that the leveling platform successfully maintains the horizontal pose on both terrains. This allows the UAV to stably take off and land in moving environments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.16-25
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• 2004

The flow and heat/mass transfer in the falling-film of a heat exchanger can be influenced by the motion of the surrounding refrigerant vapor. In this study, the effect of the vapor flow direction on the absorption heat transfer has been investigated for a falling-film helical coil which is frequently used as the absorber of ammonia/water absorption refrigerators. The experiments were carried out for different solution concentration. The heat and mass transfer performance was measured for both parallel and counter-current flow. The effect of vapor flow on the heat and mass transfer is found to be increased with decreasing solution concentration. In the experiments with low solution concentration, whose vapor specific volume is great, the counter-current flow of vapor resulted in uneven distribution of falling-film and reduced the heat transfer performance of the absorber. The direction of the vapor flow hardly affected the thermal performance as the solution concentration became stronger since the specific volume of the ammonia/water vapor was much smaller than that of the water vapor.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.2
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• pp.105-111
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• 2005

In sheet metal forming, drawbeads are often used to control uneven material flow, which may cause defects such as wrinkles, fractures, surface distortion and springback. Appropriate setting and adjusting of the drawbead force is one of the most important parameters in sheet forming process control. Therefore in this study, drawbead test was performed at various bead surface treatment conditions to clarify the frictional characteristics between sheet and drawbead. Furthermore, the differences in drawing force between circular and rectangular shape beads have also been measured to estimate the effectiveness of bead shape on the material flow control. The results show that drawing and friction characteristic were strongly influenced by surface treatments of bead and bead shapes.

• Journal of the Korean Society for Heat Treatment
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• v.29 no.6
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• pp.259-263
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• 2016

This study was carried out to investigate the effect of hot forging ratio on the microstructure and mechanical properties of incoloy 825 alloy. Hot forging was carried out at the forging ratio of 0%, 60% and 90% respectively in a range of $900^{\circ}C{\sim}1,140^{\circ}C$ and followed solution treatment was conducted at $1,000^{\circ}C$ for 1 hr. In all the specimens of hot forged of 0%, 60% and 90%, precipitates were not observed. The average grain size of 0% specimen is $82{\mu}m$ and that of 60% and 90% is $56{\mu}m$ and $31{\mu}m$, respectively. The range of grain size in the 0% specimen is uneven in $182{\mu}m$ to $31{\mu}m$, but the grain size of 90% specimen is uniform. With increasing hot forging ratio, the mechanical properties such as tensile strength, elongation, hardness increased and impact toughness increased by grain refinement.

• Journal of Sensor Science and Technology
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• v.16 no.3
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• pp.211-219
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• 2007

This paper describes the development of 6-axis force/moment sensor for a humanoid robot. In order to walk on uneven terrain safely, the robot's foot should perceive the applied forces Fx, Fy, Fz and moments Mx, My, Mz to itself, and be controlled by the foot using the forces and moments. Also, in order to grasp unknown object safely, the robot's hand should perceive the weight of the object using the mounted 6-axis force/moment sensor to its wrist, and be controlled by the hand using the forces and moments. Therefore, 6-axis force/moment sensor should be necessary for a humanoid robot's hand and foot. In this paper, 6-axis force/moment sensor for a humanoid robot was developed using many PPBs (parallel plate-beams). The structure of the sensor was newly modeled, and the sensing element of the sensor was designed using theoretical analysis. Then, 6-axis force/moment sensor was fabricated by attaching strain-gages on the sensing elements, and the characteristic test of the developed sensor was carried out. The rated outputs from theoretical analysis agree well with the results from the experiments.

• Science of Emotion and Sensibility
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• v.16 no.1
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• pp.65-74
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• 2013

The visual sensibility and preferences are closely related with color combinations, stripe intervals, and stripe complexity. We studied the effect of stripes characteristics on visual sensibility and preferences for men's shirts fabrics. As a result of a factor analysis, the adjectives were classified by viewers into 5 factors as attraction, maturity, dignity, practicality, and simplicity. We found that stripe intervals had a significant visual effect on maturity, dignity, and practicality. The uneven stripes had higher scores for dignity and practical while lower for mature. The stripes with consecutive order of two different thickness were felt more strongly in attractive, practical, and preferred. The results also showed that stripes with compound and contrast colors were attractive and preferred.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.6
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• pp.546-551
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• 2011

Tilt sensor is required to control the attitude of the biped robot when it walks on an uneven terrain. Vision sensor, which is used for recognizing human or detecting obstacles, can be used as a tilt angle sensor by comparing current image and reference image. However, vision sensor alone has a lot of technological limitations to control biped robot such as low sampling frequency and estimation time delay. In order to verify limitations of vision sensor, experimental setup of an inverted pendulum, which represents pitch motion of the walking or running robot, is used and it is proved that only vision sensor cannot control an inverted pendulum mainly because of the time delay. In this paper, to overcome limitations of vision sensor, Kalman filter for the multi-rate sensor fusion algorithm is applied with low-quality gyro sensor. It solves limitations of the vision sensor as well as eliminates drift of gyro sensor. Through the experiment of an inverted pendulum control, it is found that the tilt estimation performance of fusion sensor is greatly improved enough to control the attitude of an inverted pendulum.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.5
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• pp.310-318
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• 2016

Emerging technologies such as the Internet of Things (IoT) and the Advanced Driver Assistant System (ADAS) often have image transmission functions with tough constraints, like low power and/or low delay, which require that they adopt line-based, low memory compression methods instead of existing frame-based image compression standards. Bit rate control in the conventional frame-based compression systems requires a lot of hardware resources when the scope of handled data falls at the frame level. On the other hand, attempts to reduce the heavy hardware resource requirement by focusing on line-level processing yield uneven image quality through the frame. In this paper, we propose a bit rate control that maintains consistency in image quality through the frame and improves the legibility of text regions. To find the line characteristics, the proposed bit rate control tests each line for ease of compression and the existence of text. Experiments on the proposed bit rate control show peak signal-to-noise ratios (PSNRs) similar to those of conventional bit rate controls, but with the use of significantly fewer hardware resources.