• Journal of Astronomy and Space Sciences
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• v.36 no.4
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• pp.235-248
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• 2019

This paper suggests a relative orbit control strategy for the CubeSat Astronomy by NASA and Yonsei using Virtual Telescope Alignment eXperiment (CANYVAL-X) mission whose main goal is to demonstrate an essential technique, which is an arrangement among two satellites and a specific celestial object, referred to as inertial alignment, for a next-generation virtual space telescope. The inertial alignment system is a relative orbit control system and has requirements for the relative state. Through the proposed orbit control strategy, consisting of separation, proximity keeping, and reconfiguration, the requirements will be satisfied. The separation direction of the two CubeSats with respect to the orbital plane is decided to provide advantageous initial condition to the orbit controller. Proximity keeping is accomplished by differential atmospheric drag control (DADC), which generates acceleration by changing the spacecraft's effective cross section via attitude control rather than consuming propellant. Reconfiguration is performed to meet the requirements after proximity keeping. Numerical simulations show that the requirements can be satisfied by the relative orbit control strategy. Furthermore, through numerical simulations, it is demonstrated that the inertial alignment can be achieved. A beacon signal had been received for several months after the launch; however, we have lost the signal at present.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.123-126
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• 1997

In this study, we investigated the Pretilt ang1e generation in nematic liquid crystal (NLC) by using the transcription, alignment on polyimide(Pl) surfaces. That the uniform alignment of NLC is observed by microphotograph textures in LC cells on Pl surface. We obtained that the pretilt angle of NLC are generated about 3.6$^{\circ}$on Pl surface. It is considered that the LC alignment by transcription alignment method is attributed to memory effect of LC on Pl surface.

• Journal of Korean Society of Transportation
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• v.14 no.3
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• pp.143-154
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• 1996

Since chevron alignment sign provides a user with information of road's alignment, it plays an important role in improving the safety aspects of the highway. Currently, it is installed without reasonable design specifications and maintained under insufficient labor and working time. This study, therefore, reviewed the current specifications involving design, installation, shape, and color and several alternatives were generated. The readibility and visibility were chosen as measure of effectiveness to compass these alternatives. Furthermore, spacing of sign was evaluated. The field study resulted that yellow background with black sign was more realible and visible than the other alternatives.

• Journal of KSNVE
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• v.4 no.1
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• pp.33-42
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• 1994

When a vibration is generated due to the misalignment, the reduction of the vibration level is not attainable unless a correct shaft alignment is conducted. In a turbine system, an alignment procedure requires quite a lot amount of expense and time. To reduce this effort, an algorithm of the turbine alignment is developed to be used in the computer program. The program consists of five parts : input, calculation, display of the results, file management, and printer output. In the input part, users must provide the data on the turbine number, the reference value of the alignment, and the number of the feet of the generator. In calculation, the moving distance of the bearing and the necessary amount of the shims are calculated. In the display and the output parts, the calculated results are displayed and calculated. In the display and the output parts, the calculated results are displayed and printed. Then, by using the file management, results and procedures conducted are saved in the floppy diskette or in the hard disk. The developed program can be run in IBM PC compatible with more than 640 KB of main memory with the operating system of MS-DOS v 3.3 or higher. It is developed for novice users with no experience or specialty in this field. The program is not only useful in the power plant application, but also helpful for recording of the alignment procedures.

• The Journal of Korean Physical Therapy
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• v.26 no.4
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• pp.226-233
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• 2014

Purpose: This study was conducted in order to investigate the exercise limit that may occur depending on changes in postural alignment by examining the significance of postural alignment changes, foot pressure, and balance of patients with stroke. Methods: In this study, 50 patients diagnosed with a stroke were selected as subjects. Imbalance of postural alignment of the trunk, pelvic tilt of trunk rotation of the body, angle of kyphotic curving of the thoracic, and angle of lordotic curving of the lumbar vertebra were measured. Foot pressure was examined by measuring average pressure and weight bearing. Balance was examined by measuring the center of pressure and limit of stability. Results: The significance of postural alignment, foot pressure, and weight bearing of the non-paretic side was examined. In addition, the significance between postural alignment and balance was examined. Conclusion: It is thought that limits of foot pressure and balance in the standing position can be caused by postural alignment. Thus, both a therapeutic intervention program and postural alignment training should be provided together in order to improve the function of patients with stroke.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.271-276
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• 2006

Railroads made many contribution to modernization being developed so quickly as public transportation, but after middle of 20 century, its qualities are getting low because of focusing on the investment and development of cars and airplanes. Its role which is getting the excellent merits on the mass transportation, rapid transit. safety, state period, energy efficiency, and prevention of environmental pollution has been reconsidered. Element of horizontal alignment In an existing railroad line is needed as basic materials, when it will be improved or moved. If its design drawing was lost or damaged, it is impossible to recover. It is riot easy to repair for it as disasters. We must understand an existing railroad line to bring a function included a basic geography situation. In this studies we acquire, analyze. and handle the digital picture of railroads and then reappear shape of three dimension. But also we want to contribute to establish the facilities information choosing materials of existing railroad line in outputting the alignment element by reverse.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.756-760
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• 2011

This paper proposed an alignment stage driven by piezo actuators for alignment process of a contact-type lithography. Among contact-type lithography processes, an UV-curable nanoimprint process is an unique process to be able to align patterns on upper and lower layers. An alignment stage of the UV-curable nanoimprint process requires nano-level resolution as well as high stiffness to overcome friction force due to contact moving. In this paper, the alignment stage consists of a compliant mechanism using flexure hinges, piezo actuators for high force generation, and capacitive sensors for high-resolution measurement. The compliant mechanism is implemented by four prismatic-prismatic compliant chains for two degree-of-freedom translations. The compliant mechanism is composed of flexure hinges with high stiffness, and it is directly actuated by the piezo actuators which increases the stiffness of the mechanism, also. The performance of the ultra-precision stage is demonstrated by experiments.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.3
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• pp.645-652
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• 2016

At the initial stage of propulsion shaft design, in line with shaft alignment, an intensified consideration of lateral vibration is needed to verify its operational safety. Recently the alignment problem affecting the lateral vibration has been becoming issues. However, the theoretical method of forced lateral vibration analysis is not cleary established so far and it is about to simply limited among the classification societies and international standards to avoid the blade natural frequency resonance cpm outside of ${\pm}20%$ of engine rpm at MCR. On the other hand, longer center distance between each support bearing shows an affirmative result normally in shaft alignment analysis whereas the blade order resonance speed may cause lowering near the limitation in the aspect of lateral vibration. Therefore, it is required careful attention to engineers as described above. As a method to solve the problem, it is mainly considered that remove forward stern tube bearing. In this paper, based on a medium size container ship case, theoretical study was carried out in the context of the forward stern tube bearing. The various effects and functions of forward stern tube bearing are reviewed and evaluated. Then an guidance note to lead the conclusion is proposed.

• International Journal of Highway Engineering
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• v.14 no.1
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• pp.1-8
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• 2012

The horizontal alignment of road is deeply related with the stability of the road and traffic capacity. It is necessary to analyze horizontal alignment of road accurately for efficient maintenance of the road and relevance judgment about the standard. Recently the study on horizontal alignment of road using Lidar data and GPS was concluded, but they were many problem analyzing horizontal alignment radius of curvature in wide area. In this study, the tool which the radius of curvature can evaluate the suitability about "Rules about the Road Structure & Facilities Standards" by using center lines of the road of the digital map tries to implement on GIS. The interface was designed and implemented which can automatically estimate the Road Centerline Horizontal Alignment by using $ESRI^{(R)}$ $ArcObject^{TM}$.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.30-35
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• 2019

Inertial measurement units (IMUs) are widely used for wearable motion-capturing systems in the fields of biomechanics and robotics. When the IMUs are combined with optical motion sensors (hereafter, OPTs) for their complementary capabilities, it is necessary to align the coordinate system orientations between the IMU and OPT. In this study, we compare the application of two coordinate transformation-based orientation alignment methods between two coordinate systems. The first method (M1) applies angular velocity coordinate transformation, while the other method (M2) applies gyroscopic angle coordinate transformation. In M1 and M2, the angular velocities and angles, respectively, are acquired during random movement for a least-square algorithm to determine the alignment matrix between the two coordinate systems. The performance of each method is evaluated under various conditions according to the type of motion during measurement, number of data points, amount of noise, and the alignment matrix. The results show that M1 is free from drift errors, while drift errors are present in most cases where M2 is applied. Thus, this study indicates that M1 has a far superior performance than M2 for the alignment of IMU and OPT coordinate systems for motion analysis.