• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3115-3123
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• 1993

This paper presents a real-time correction method of the movemont errors of a translatory precision machine axis. This method is a null-balances technique in which two plane mirrors are used to generate an interferometric fringe pattern utilizing the optical principles of TwymanGreen interferometry. One mirror is fixed on a reference frame, while the other is placed on the machine axis being supported by three piezoelectric actuators. From the fringe pattern, one translatory and two rotational error components of the machine axis are simultaneously detected by using CCD camera vision and image processing techniques. These errors are then independently suppressed by activating the peizoelectric actuators by real-time feedback control while the machine axis is moving. Experimental results demonstrate that a machine axis can be controlled with movement errors less than 10 nm in vertical straightness, 0.1 arcsec in pitch, and 0.06 arcsec in roll for 50mm travel by adopting the real-time correction method.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.1984-1986
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• 2001

In order to provided continuous solutions, latest developing navigation systems tend to integrate GPS receiver with INS or DR. Using the GPS carrier-phase measurements, an attitude GPS receiver with three antennas obtain the 3-dimensional attitude such as roll, pitch, and heading as well as position and velocity. With these angle measurements, in the attitude GPS/INS integrated system, attitude or gyro errors can be directly compensated. In this paper, we develop an integrated navigation system that combines attitude GPS receiver with INS. The performance of real-time integrated navigation system is determined by not only the implements of integration filter but also the synchronization of measurements. To meet these real-time requirements, the navigation software is implemented in multi-tasking structure in this paper. We also employ time-synchronization technique in the multi-sensor fusion. Experimental results show that the performance of the attitude GPS/INS integrated system is consistent even when cycle-slip occurs in carrier-phase measurements.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.496-499
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• 1995

Amorphous $Co_{80+x}TM_{12}B_{8-x}$ (TM = Ti, Zr, Hf, Nb and x = 0, 2, 4 at%) alloys were prepared by single roll melt spinning technique. Saturation magnetization of the amorphous ribbons was measured by SQUID and vibrating sample magnetometer from 5 to 800 K under applied fields up to 10 kOe. Typical thermo-magnetization curves were observed and the average values of the spectroscopic splitting g factor were estimated from the ferromagnetic resonance curve. For all the amorphous alloys studied here the saturation magnetization in the temperature range 5 K up to about $0.3T_{c}$ can be described by the Bloch relation: $M_{s}(T)\;=\;M_{s}(0)(1-BT^{3/2}-CT^{5/2})$. From the values of $M_{s}(0)$, B and spectroscopic splitting g factor the spin wave stiffness constants were calculated.

• Tribology and Lubricants
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• v.39 no.2
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• pp.56-60
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• 2023

In this study, we evaluate the anisotropic flow of droplets according to the directionality of asperities. We manufacture a mold with an inclined hole by adjusting the jig angle using a high-power diode laser. Using the manufactured mold, we prepare specimens for wettability studies by the micro molding technique. We fabricate twelve kinds of surfaces with micro-asperities inclined at 0°, 15°, 30°, and 45° for asperity pitches of 100 ㎛, 200 ㎛, and 300 ㎛. We evaluate the static and dynamic behaviors of the droplets as a function of the asperities pitch and inclination angles. The anisotropic effect increases as the pitch increases between asperities, and the anisotropic flow characteristics increase as the inclination angle of the asperities increases. On the surface with hole pitches of 100 ㎛ and 200 ㎛, the contact angle of the droplet shows high hydrophobicity at approximately 160°, but on the surface with the 300-㎛ hole pitch, the contact angle is approximately 110°, indicating that the hydrophobic effect rapidly reduces. Additionally, when the inclination angle of the asperities is approximately 30°, the left and right contact angle deviations of the droplet are the lowest, showing that the roll-off angle is relatively low.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.2
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• pp.437-444
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• 2024

The rotational inertial navigation system can provide more accurate navigation information by mounting an IMU (Inertial Measurement Unit) on the gimbal and rotating the gimbal regularly to cancel out the errors of the IMU. However, when an attitude change occurs due to waves, the attitude error is not removed to 0 at the end of one cycle of the rotation procedure and causes a large position error. In this paper, considering this problem, we propose a method of stabilizing the external gimbal by rotating it based on the roll information of the vehicle. Based on simulation, the impact of waves is analyzed and the performance of external gimbal stabilization is verified.

• Journal of Industrial Convergence
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• v.18 no.3
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• pp.63-72
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• 2020

This study investigated up-styling techniques as related to wedding dress image. To find up-styles that fit well with a wedding dress, a questionnaire survey was conducted targeting hairdressers in the beauty industry, and new styles were created and suggested based on the survey results. For this, hair was slicked back without parting and combed upward. Then, using braiding techniques needed to produce a top point, styles were created to create attractive images. For up-styles that go with an elegant wedding dress, hair was parted in a ratio of 3 : 7. In addition, a roll technique was applied based on natural points by keeping the ears half-covered to create elegance. For up-styles that are perfect for a classic wedding dress, hair was parted in a ratio of 2 : 8, keeping the ears half-covered. Based on the back point, a twisting technique was applied to create classic images. It is anticipated that the study results would provide basic data needed for creating and understanding up-styles that go with various wedding dress images and make a contribution to their development.

• Polymer(Korea)
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• v.27 no.5
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• pp.436-442
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• 2003

Thermosetting elastomer such as EPDM (Ethylene Propylene Dien Rubber) has been applied to the sponge weatherstrip of a vehicle as a main material. However, the thermosetting elastomers have limited recycling and have brought about the environmental problems. Furthermore, many steps of the manufacturing process such as formulation, mastication and vulcanization make difficult to control uniformity of the endproducts. These problems of current EPDM weatherstrip necessitated development of a new recyclable material, Thermoplastic Vulcanizates (TPV). In this study the influence of the water contents, and the processing conditions. On the foam density and structure in water blowing process was carried out. We found that TPV also can be foamed with water, maintaining the uniformity form this study. Therefore, many inevitable problems of EPDM weatherstrip can be solved, and this new technique is expected to take a roll of making a breakthrough in the rubber industry.

• Archives of Plastic Surgery
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• v.32 no.1
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• pp.117-123
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• 2005

The reconstructive modalities for vaginal reconstruction include simple dilatation, skin graft, use of intestinal segments and various methods using flaps. However, skin grafting procedure is the most commonly used technique and the McIndoe procedure is a representative technique among skin grafting procedures. McIndoe procedure is easier, faster and has a lower morbidity compared to other techniques. However the conventional McIndoe procedure has several problems such as incomplete vestibule formation, excessive bleeding during dissection, possibility of recto-vaginal or urethro-vaginal fistula formation, late vaginal contracture and discomfort in wearing hard plastic mold for a long time after operation. To solve these problems, the authors modified the conventional McIndoe procedure in several perspectives. The undeveloped vestibule was incised with X-shaped mucosal incision between the urethral opening and posterior margin of the vestibule and deepened by blunt finger dissection to provide a sufficient diameter & length of the neovagina and to minimize bleeding. A sizable medium thickness split skin graft was harvested and wrapped over a roll gauze-filled condom mold. Applying multiple stab incision on the skin grafted condom mold, it was inserted into the prepared neovaginal canal. Distal margin of the skin graft was secured with tips of the mucosal flaps created by X-shaped vestibular incision to prevent accidental extrusion of the skin grafted mold. During last 15 years, we applied this modification to 20 vaginal agenesis patients and investigated results of the 12 patients who could be followed up serially including hematoma formation and skin graft survival rate, size, depth, presence of late contracture, appearance, comfortness, and hygiene of the neovagina. And they were compared with 8 patients of 20 patients who underwent conventional McIndoe procedures. The modified McIndoe procedure revealed lower complication rate, higher patient satisfaction and better functional results.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.4
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• pp.517-526
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• 2019

In the present study, unsteady flows around a projectile ejected from an aircraft platform have been numerically investigated by using a three dimensional compressible RANS flow solver based on unstructured meshes. The relative motion between the platform and projectile was described by six degrees of freedom(6DOF) equations of motion with Euler angles and a chimera technique. Initial behavior of the projectile for varying conditions, such as roll and pitch-yaw command on the control surface of the projectile, flight Mach number, and platform pitch angle, was investigated. The ejection stability of the projectile was degraded as Mach number increases. In the transonic condition, the initial behavior of the projectile was found to be unstable as increase of platform pitch angle. By applying the command to control surfaces of the projectile, initial stability was highly enhanced. It was concluded that the proposed simulation data are useful for estimating the ejection behavior of a projectile in design phase.

• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.433-440
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• 2022

Recently, owing to global warming, average summer temperatures are increasing and the number of hot days is increasing is increasing, which leads to an increase in heat stroke. In particular, outdoor workers directly exposed to the heat are at higher risk of heat stroke; therefore, preventing heat-related illnesses and managing safety have become important. Although various wearable devices have been developed to prevent heat stroke for outdoor workers, applying various sensors to the safety helmets that workers must wear is an excellent alternative. In this study, we developed a smart helmet that measures various vital signs of the wearer such as body temperature, heart rate, and sweat rate; external environmental signals such as temperature and humidity; and movement signals of the wearer such as roll and pitch angles. The smart helmet can acquire the various data by connecting with a smartphone application. Environmental data can check the status of heat wave advisory, and the individual vital signs can monitor the health of workers. In addition, we developed an algorithm that classifies the risk of heat-related illness as normal and abnormal by inputting a set of vital signs of the wearer using a support vector machine technique, which is a machine learning technique that allows for rapid binary classification with high reliability. Furthermore, the classified results suggest that the safety manager can supervise the prevention of heat stroke by receiving feedback from the control system.