• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.88-94
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• 2005

A swirl ratio of a charge in the cylinder could be calculated by measuring both the rotary speed of paddle and the intake air flow rate in the swirl measurement apparatus fur several positions of valve lift. The automation of the swirl ratio measurement for a cylinder head is achieved by controlling both the valve lift of cylinder head and a suction pressure of the surge tank, instead of controlling them manually. PID control of the surge tank pressure and positioning a valve lift of the cylinder head are also achieved by using two step motors, respectively. Rotating speed of a paddle are measured using an optical sensor and a counter. Flow rate are measured from ISA 1932 flow nozzle by reading a differential pressure gauge position using IEEE-1394 camera. Time to measure the swirl ratio for a port in the cylinder head is drastically reduced from an hour to 3 minutes by automation control of the apparatus.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.9
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• pp.883-890
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• 2006

Nowadays, CPS is used widely, especially in cases which need more precise position information, such as car navigation systems and even in the mobile robot for position measuring in the outdoor environment. RTK (Real-Time Kinematics) and DGPS (Differential Global Positioning System) have more precise accuracy than the general-purposed GPS. However can't easily use them because of high prices and large size of equipments. In order fur the mobile robot to obtain precise position information it is important that CPS receiver has portability and low price. In this study, we introduce a new GPS data acquisition system that offers the precise position data using the DGPS mechanism and satisfying low cost and portability. In addition to this, we propose an improved data compensation algorithm that offers more accurate position information to the outdoor mobile robot by compensating the error rate of CPS data measured from the three points with geometrical rotation and distance formula. Proposed method is verified by comparing with the precise real position data obtained by RTK. Proposed method has more than 70% performance enhancement.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.175-177
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• 2006

According to the recommendation of International Maritime Organization, the Ministry Of Maritime Affairs and Fisheries (MOMAF) of Korea provides the real time Differential Global Positioning System service using maritime radio beacon from 1999. Due to the benefit of DGPS service, the need of this system is increased from various user groups for acquiring the better accuracy and integrity. Therefore, MOMAF has extended their service to inland by installing the additional 6 DGPS stations. This nationwide DGPS service will be fully deployed at 2007. In addition to the extension of service area, MOMAF has a plan to upgrade their nationwide DGPS to High Accuracy Nationwide DGPS (HANDGPS). The planned HANDGPS service of Korea will be a kind of long range RTK or Wide Area RTK techniques to provide under 1m accuracy and start their service from 2009 using the various broadcasting and communication media like as radio beacon, Wibro, Digital Multimedia Broadcasting, High Speed Packet Data Access. The introduction of nationwide DGPS system of Korea and its evolution plan will be addressed in this paper. The research activities related with HANDGPS in Korea is also presented.

• Journal of Navigation and Port Research
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• v.31 no.10
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• pp.859-864
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• 2007

In the future, it is necessary that using the Satellite-based radio navigation augmentation system such as Differential Global Positioning System(DGPS) to achieve a position accuracy of sub-meter level in port. Generally, the receiver for DGPS reference station should meet performance specifications of RSIM Ver. 1.1 presented by RTCM. This paper proposes a method to verify performance of the receiver for DGPS reference station according to the RSIM Ver. 1.1. And this paper presented that performance evaluation of the commercial receiver for DGPS reference station through the proposed method is satisfied with RSIM Ver. 1.1.

• Journal of Power Electronics
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• v.9 no.1
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• pp.74-84
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• 2009

The design and implementation of a high performance PID (Proportional Integral & Differential) style controller with zero-phase error tracking property is considered in this article. Unlike a ball screw driven system, the controller in a direct drive system should provide a high level of tracking performance while avoiding the problems due to the absence of the gear system. The stiff mechanical element in a direct drive system allows high precise positioning capability, but relatively high tracking ability with minimal position error is required. In this work, a feasible position controller named 'Unified PID controller' is presented. It will be shown that the function of the closed position loop can be designed into unity gain system in continuous time domain to provide minimal position error. The focus of this work is in two areas. First, easy gain tunable PID position controller without speed control loop is designed in order to construct feasible high performance drive system. Second, a simple but powerful zero phase error tracking strategy using the pre-designed function of the main control loop is presented for minimal tracking error in all operating conditions. Experimental results with a s-curve based position pattern commonly used in industrial field demonstrate the feasibility and effective performance of the approach.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.5
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• pp.505-516
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• 2003

The purpose of this study was to develop the measurement of fashion sensibility and to verify the validity and utility. The survey has been done 91 photos selected in fashion magazines with 25 semantic differential hi-polar scale. The obtained data were analyzed by MDS, Discriminant analysis and Regression analysis. The major findings of this research were as follows. 1. According to the sensibility positioning, fashion image was classified by 4 group and agreed with constructing factors of fashion. 2. As result of the discrimination analysis, distinguishable fashion sensibility among design elements of clothing was related to refined, pleasant, feel like buying sensibility. 3. As result of the regression analysis, Preference was related to looking good, refined, and sweet, Buying needs related to likable, looking good and natural, Riches related to elegant, neat and refined, Pleasure related to looking good, elegant and bright. 4. The fashion design properties were different regarding Preference, Buying needs. Riches and Pleasure. Preference and Buying needs were related to H-line, similarity color combination, cotton and linen, Riches related to brilliance texture, ruffle and flounces, Pleasure related to fit and sexy design of clothing.

• Journal of Biosystems Engineering
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• v.27 no.2
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• pp.143-150
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• 2002

Several researches for site-specific weed control have tried to increase accuracy of weed detection with machine vision technique. However, there is a problem which needs substantial time to perform site-specific spraying. Therefore, new technology for real-time precision spraying system is needed. This research was executed to develope the new technology to estimate weed density and size in real time, and to conduct a real-time site-specific spraying. It would effectively reduce herbicide amounts applied for a crop field. The real-time precision spraying system consisted of a Differential Global Positioning System (DGPS) with an error of 2 cm, a machine vision system, a geomagnetic sensor for correction of view point of CCD camera and an automatic sprayer with separately controlled nozzle. The weed density was calculated with comparison between position information and a pre-designed electronic map. The position information was obtained in real time using the DGPS and the machine vision. The electronic map contained a position database of crops automatically constructed when seeding. The developed system was tested on an experimental field of Seoul National University. Success rate of the spraying was about 61%.

• Journal of Biosystems Engineering
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• v.25 no.4
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• pp.301-310
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• 2000

An autonomous tractor system was developed and its performance was evaluated. The system consisted of a tractor system of and a remote control station. The tractor and the remote control station communicated each other via wireless modems. The tractor had a DGPS(differential global positioning system), sensors, a controller and a modem. The DGPS collected position data and the tractor status was estimated. The information of tractor status and sensors was transferred to the remote control station. Then, the control station determined the control data such as steering angles using a fuzzy controller. The fuzzy controller used the information from the DGPS, sensors, and GIS(geographic information system) data. The control data were obtained by remote signal processing at the control station The control data for autonomous operation were transferred to the tractor controller. The performances of an autonomous tractor were evaluated for various speeds, different initial positions and different initial headings. About 1.3 seconds of time lag was occurred in transferring the tractor status data and the control data. Compensation the time lag, about 27cm deviation was observed at the speed of 0.5m/s and 37cm at the speed of 1m/s. Error caused mainly by the time lag and it would be reduced by developing a full-duplex radio module for controlling the remote tractor.

• International Journal of Automotive Technology
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• v.8 no.5
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• pp.583-591
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• 2007

This paper describes the development of the $H_{\infty}$ lateral control system for an autonomous ground vehicle operating a limited area using the RTK-DGPS(Real Time Kinematic-Differential Global Positioning System). Before engaging in autonomous driving, map data are acquired by the RTK-DGPS and used to construct a reference trajectory. The navigation system contains the map data and computes the reference yaw angle of the vehicle using two consecutive position values. The yaw angle of the vehicle is controlled by the $H_{\infty}$ controller. A prototype of the autonomous vehicle by the navigation method has been developed, and the performance of the vehicle has been evaluated by experiment. The experimental results show that the $H_{\infty}$ controller and the RTK-DGPS based navigation system can sufficiently track the map at low speed. We expect that this navigation system can be made more accurate by incorporating additional sensors.

• Journal of Astronomy and Space Sciences
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• v.19 no.4
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• pp.367-376
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• 2002

As of September 2002, there are more than 60 operational permanent Global Positioning System (GPS) stations in South Korea. Their data are being used for a variety of purposes: geodynamics, geodesy, real-time navigation, atmospheric science, and geography. Especially, many of the sites are reference stations for DGPS (Differential GPS). However, there has been no comprehensive and qualitative analysis published to evaluate the data quality. In this study, we present preliminary results of our assessment of the permanent GPS sites in South Korea. We have analyzed the multi-path characteristics of each station using a quality-checking software package called TEQC. Another multipath analysis tool based on post-fit phase residuals was used to check the repeating patterns and the amount of the multipath at each site. The long-term stability of each station was analyzed using the root-mean-square (RMS) error of the estimated site positions for one year, which enabled us to evaluate the mount stability. In addition, the number of cycle slips at each site was derived by TEQC. Based on these series of tests, we compared the stability and data quality of permanent GPS stations in South Korea.