• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.10
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• pp.703-713
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• 2004

This paper presents the new obstacle avoidance method that is composed of vision and sonar sensors, also a navigation algorithm is proposed. Sonar sensors provide poor information because the angular resolution of each sonar sensor is not exact. So they are not suitable to detect relative direction of obstacles. In addition, it is not easy to detect the obstacle by vision sensors because of an image disturbance. In This paper, the new obstacle direction measurement method that is composed of sonar sensors for exact distance information and vision sensors for abundance information. The modified splitting/merging algorithm is proposed, and it is robuster for an image disturbance than the edge detecting algorithm, and it is efficient for grouping of the obstacle. In order to verify our proposed algorithm, we compare the proposed algorithm with the edge detecting algorithm via experiments. The direction of obstacle and the relative distance are used for the inputs of the fuzzy controller. We design the angular velocity controllers for obstacle avoidance and for navigation to center in corridor, respectively. In order to verify stability and effectiveness of our proposed method, it is apply to a vision and sonar based mobile robot navigation system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.393-396
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• 2000

Spent fuel rod cutting device should cut a spent fuel rod to an optimal size in order to fast decladding operation. In this paper, for developing spent fuel rod cutting device with cutter blade, rod properties such as dimension and material of zircaloy tube and fuel pellet are investigated at first and then, various methods of existing cutting devices used commercially are investigated and their performance are analyzed and compared. This device is designed to be operated automatically via remote control system considering later use in Hot-Cell (radioactive area) and the mdularization in the structure of this device makes maintenance easy. SUS and Zircaloy-4 are selected as cut material used in the test of spent fuel rod cutting device by cutter blade. In order for constructing the high durable cutter blade, various materials are analyzed in terms of quality, shape, characteristic, and heat treatment, etc. and from these results, spent fuel rod cutting device is designed and manufactured based on the considerations of durability, round shape sustainability of rod cross-section, debris generation, and fire risk, etc.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1636-1647
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• 1997

As most of today's automatic transmissions in passenger car adopt a electro-hydraulic control system, the role of electronically controlled solenoid valves occupies an important position and it is essential to predict solenoid transient characteristics in order to design and evaluate the performance of the hydraulic control system. However, in general, both the magnetic and electrical parameters f the solenoid system are hardly known and it is not easy to model this section with moderate complexity although mechanical system could be developed using the classical second order system. This paper presents a dynamic modelling technique of a solenoid valve, that is controlled by pulse width modulation for an automatic transmission, in terms of system identification theory. In nonlinear computer simulation, it is shown that the identified systems which produce magnetic force to input duty cycle for various excitation signals predict the static and dynamic performance very well near the operating point and in experiment conducted to confirm the validity of identification theory for PWM solenoid valve, we find that there is a good agreement between the experimental data and simulation result. Hence, this model can be utilized in the development of pressure control system with PWM solenoid valve.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.1
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• pp.89-96
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• 2015

The various services applied internet have been provided by the rapid development of wireless networks and providing multimedia contents are also increasing. It is caused a number of problems such as increasing of network traffic rapidly. P2P technique is gaining popularity for solving these problems. In particular, P2P technique in a wireless network environment has gained much popularity. Among them, MANET-based P2P techniques has been studied actively. It is not easy to be applied the existing technique as it is due to the dynamic topology and low bandwidth by moving nodes in MANET that is consisted of only mobile nodes. In this paper, we proposed sharing group construction technique for providing a stable connection between mobile nodes and reducing the load of network traffic and overhead of sharing group reconfiguration in order to improve data transmission performance between mobile nodes. The sharing group member nodes applied virtual sharing group generation technique with neighboring nodes of 1-hop distance in order to reduce traffic for file sharing. We performed comparative experiments with DHT technique to evaluate the performance of the proposed technique in this paper and the excellent performance is confirmed through experiments.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.50-55
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• 2008

In general, the swing motion of the crane is controlled and suppressed by activating the trolley motion. In many papers reported by us, we suggested a new type of anti-sway control system of the crane. In the proposed control system, a small auxiliary mass(moving-mass) is installed on the spreader and the swing motion is controlled by moving the auxiliary mass. The actuator reaction against the auxiliary mass applies inertial control forces to the container in order to reduce the swing motion in the desired manner. Futhermore the measuring systems based on image sensor have been proposed also. To obtain the robustness for our control system, $H_{\infty}$ based control techniques and other approach have been applied to suppress swing motion. As well known, the robust control technologies based on $H_{\infty}$ control need complicated and difficult process. In the result, the obtained closed-loop system becomes to high order system which may give us many difficulties to apply it to the real plants. Therefore, we introduce an easy approach which is based on LQ control theory. In this approach, we introduce the frequency dependent weighting matrices which give the system filters to shape frequency characteristics of the controlled system and guarantee the control performance.

• Journal of Korean Society for Geospatial Information Science
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• v.4 no.2 s.8
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• pp.79-90
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• 1996

It is well known that point positioning using a C/A-code receiver is severely biased by errors in pseudorange. This paper shows the procedures of quantitive analysis for several error elements and that some methods to monitor SA(selective availability) of witch process is not opened are proposed. It is possible to verify the effects of SA in the Doppler shift and receiver clock drift variation. Easy methods to reduce SA effects are to fit second order polynomials for the one and a linear function for the other. With periodic autocorrelation functions. SA effects are analyzed and first order Gauss-Markov process parameters are decided.

• Journal of the Korean Association of Geographic Information Studies
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• v.1 no.2
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• pp.37-43
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• 1998

This paper presents a KITSAT-3 image catalog browse and distribution system. The access time and easy-to-use concept of the system should be highlighted in order for satellite image users to browse and order the required images as quickly and easily as possible. In general, users want to enter their image search conditions in the simplest ways and to display the search results which can be interpreted intuitively. The KITSAT-3 image catalog browse and distribution system was developed to satisfy the users' requirements with the minimum system installation cost.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.109-110
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• 2018

Preloading Strut applied during installation of the wall jack, but additionally serves to minimize the displacement of soil pressure acting upon dissolution due to the difficulty. In this study, we developed an index of support for the release of stress to facilitate the dismantling of the strut uninstall. The refractive support the axial force acting on the strut are supportable, is refracted at minimum load, disassembly should be easy. In order to find the optimal shape and structural stability of the refractive support We have performed the numerical analysis and performance test to determine the final model. We carried out model tests and UTM test in order to understand the refractive performance and durability of the refractive support for optimal model. Results of the test UTM is refracted all shot 5 times within a target hit number, it was found that there is no problem of the refractive performance. Further, the results of model experiments, it was found that to ensure sufficient durability more than the performance target value of the pin joint support structure.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.134-139
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• 2011

Since large and small scale photovoltaic(PV) systems have been commercialized in many countries, it is necessary to assess the effects of PV systems on the electric power system. For this, the development of accurate simulation model of PV arrays is very important. PSCAD/EMTDC, a widely used simulation tool for analyzing the transient behavior of electrical apparatus and networks, does not have a standard model of a PV array. Therefore in order to simulate the PV array, users have to develop their own simulation model. However, the block-diagram-based model is very complicated, and it is hard to modify the model parameters. In this study, we develop the user-defined model of a PV array by using the Design Editor, which is provided by PSCAD program. The mathematical model of a PV array and the method to determine the parameters of nonlinear I-V equation are implemented in a Fortran code. The graphical user interface provides the users with easy and simple way to modify the PV array parameters and simulation conditions. In order to help the users, this model also provides the parameters of 10 commercial PV arrays.

• The Journal of Pediatrics of Korean Medicine
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• v.13 no.1
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• pp.239-252
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• 1999

Selection of therapeutic modality for 114 patients with night crying was clinical1y recorded from October 1st, 1996. to Spring 1st, 1998. 1. The number of male cases was 67 (58.77%) and female cases was 47 (41.23%) and so male cases were 1.43 more than female. The patients between 7 and 12 months were 28.07% (most frequent), between 3 and 6 months were 23.68%, 1 and 3 years were 21.05%. 2. Duration of disease was for 7 days to 6 months and over, and the group within 7 days highest portion as 57.25%, between 1 and 4 weeks was 21.05%, 6 months and over was 12.28%. 3. Distribution of contributing factors was in the order of 50% of nonspecific factors, 17.54% of fall-down. 4. Distribution of complicated signs, in order of 39.47% of poor sleeping, 33.33% of easy surprizing, 16.67% of green stool, 10.53% of loose form stool. 5. Distribution of theraphic method was as follows: ⅰ) group treated with acupunture and woohwangporyonghwan(WPH) (35.09%), ⅱ) acupunture, WPH, and Gamiyangshintang(33.33%), ⅲ) acupuncture, WPH, and Hyangshapungyuisan (15.79%), 6. From the above results a remakable effct was 92.1%, of which 74.56% was excellent and 17.54% was good.