• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.164-169
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• 2000

Recently, High accuracy and precision are required in various industrial field especially, semiconductor manufacturing apparatus, Ultra precision positioning apparatus, Information field and so on. Positioning technology is a very important one among them. As such technology has been rapidly developed, this field needs the positioning accuracy as high as submicron. It is expected that the accuracy of 10nm and 1nm is required in precision work and ultra precision work field, respectively by the beginning of 2000s. High speed and low vibration are also needed. This work deals with the design method and control system of Ultra precision positioning apparatus. Control performance and stability analysis were performed in advance by modeling and designing the controller with Simulink.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.33-38
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• 2012

The wafer positioning robot in the semiconductor industry is required to operate at high speed for the improvement of productivity. The residual vibration caused by the high speed of the wafer positioning robot, however, makes the life of the robot shorter and the cycle time longer. In this study, the input shaping and the path of the system are designed for the reduction of the residual vibration and the improvement of the cycle time. The followings are the process for the reduction and the improvement; 1) System modeling of the wafer positioning robot, 2) Verification of dynamic characteristics of the wafer positioning robot, 3) Input shaping plan using impulse response reiteration, 4) Simulation test using SIMULINK program, 5) Analysis of result.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.49-53
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• 2007

In this study, we investigated experimentally the potential of a planer positioning mechanism with three degrees of freedom using a flexure guide and an electromagnetic linear motor. The goal was to produce a multi-axis positioning system with nanometric resolution over a 1-mm stroke. An $X-Y-\theta$ stage was designed based on previous results from a single-axis prototype and was constructed with a flexure guide mechanism and voice coil motor type linear actuators. We examined the necessity of a driving method and control system to ensure high resolution for multi-axis positioning. Experiments were conducted to evaluate the performance, and the results confirmed the mechanism's potential; fine point-to-point (PTP) positioning was achieved over a 1-mm stroke, with a resolution of 2 nm for translation in X-Y and 0.01 asec for yaw in $\theta$.

• Proceedings of the Korea Port Economic Association Conference
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• 2006.08a
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• pp.253-276
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• 2006

This paper has shown the trend of competition positioning of 26 Korean ports in 1994, 1999, and 2003 by using BCG matrix which consists of relative market shares, growth rate of cargo handling, and also growth rate and CCR and BCC efficiency scores with scale efficiency scores in the vertical and horizontal axes. The empirical main results are as follows. First, Incheon Port, Pyungtag Port, Gwangyang Port, Busan Port, Pohang Port and Woolsan Port have shown their competitive positioning in terms of market share and growth rate. Second, Pyungtag Port, Wando Port, Tongyoung Port, Gohyun Port, Samcheog Port, and Okgae Port have their competitive positioning in terms of growth rate and scale efficiency scores. The main policy implication of this paper is to emphasize that BCG matrix method using in this paper can give seaport manager the basic information for planning the future port management for enhancing the competitive positioning among Korean seaports.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.263-268
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• 2022

Precise Point Positioning-Real Time Kinematic (PPP-RTK) is a high accuracy positioning method that combines RTK and PPP to overcome the limitations on service coverage of RTK and convergence time of PPP. PPP-RTK provides correction data in the form of State Space Representation (SSR), unlike RTK, which provides measurement-based Observation Space Representation (OSR). Due to this, PPP-RTK has an advantage that it can transmit less data than RTK. So, recently, several techniques for PPP-RTK have been proposed. However, in order to utilize PPP-RTK techniques, performance analysis of these in a real environment is essential. In this paper, we implement the local network PPP-RTK and analyze the positioning performance according to the distance within 100 km from the reference station in Korea. As results of experiment, the horizontal and vertical 95% errors of local network PPP-RTK were 6.25 cm and 5.86 cm or less, respectively.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.1
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• pp.49-54
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• 2021

Indoor positioning system becomes of increasing interests due to the demands for accurate indoor location information where Global Navigation Satellite System signal does not approach. Wi-Fi access points (APs) built in many construction in advance helps developing a Wi-Fi Received Signal Strength Indicator (RSSI) based indoor localization. This localization method first collects pairs of position and RSSI measurement set, which is called fingerprint database, and then estimates a user's position when given a query measurement set by comparing the fingerprint database. The challenge arises from nonlinearity and noise on Wi-Fi RSSI measurements and complexity of handling a large amount of the fingerprint data. In this paper, machine learning techniques have been applied to implement Wi-Fi based localization. However, most of existing indoor localizations focus on single position estimation. The main contribution of this paper is to develop multi-target localization by using deep neural, which is beneficial when a massive crowd requests positioning service. This paper evaluates the proposed multilocalization based on deep learning from a multi-story building, and analyses its learning effect as increasing number of target positions.

• Journal of Navigation and Port Research
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• v.43 no.1
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• pp.23-32
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• 2019

In this paper, we proposed a multi-chain Time of Arrival (ToA) positioning method to estimate positions using all received Loran-C signals from multiple chains without constraining to a single chain. Conventionally, we have to choose only one chain among several available chains for position estimation using Loran-C. Therefore, the number of signals to be used for positioning is limited to three to five. In general, if more signals are used for positioning estimation, its performance tends to be improved in terms of accuracy and availability. To validate the proposed method for multi-chain Loran-C, we firstly carried out a static positioning test in land. By analyzing the test results, we confirmed that the proposed method works well under a multi-chain Loran-C scenario. Subsequently, another mobile positioning test was conducted on board a vessel under a practical application scenario. From this second test, we successfully demonstrated that the multi-chain ToA positioning method even in situations where the conventional single-chain Loran-C approach fails for positioning.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.4
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• pp.205-211
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• 2015

The Global Navigation Satellite System (GNSS) is undergoing dramatic changes. Nowadays, much more satellites are transmitting navigation data at more frequencies. A multi-GNSS analysis is performed to improve the positioning accuracy by processing combined observations from different GNSS. The multi-GNSS technique can improve significantly the positioning accuracy. In this paper, we present a combined Global Positioning System (GPS), the GLObal NAvigation Satellite System (GLONASS), the China Satellite Navigation System (BeiDou), and the Quasi-Zenith Satellite System (QZSS) standard point positioning (SPP) method to exploit all currently available GNSS observations at Mokpo (MKPO) station in South Korea. We also investigate the multi-GNSS data recorded at MKPO reference station. The positioning accuracy is compared with several combinations of the satellite systems. Because of the different frequencies and signal structure of the different GNSS, intersystem biases (ISB) parameters for code observations have to be estimated together with receiver clocks in multi-GNSS SPP. We also present GPS/GLONASS and GPS/BeiDou ISB values estimated by the daily average.

• The Korean Journal of Rehabilitation Nursing
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• v.2 no.2
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• pp.163-175
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• 1999

This study was done to identify the effectiveness of a proper positioning on musculoskeletal complication on patient with Stroke by using a quasi-experimental study. A total of 18 patients were selected as a subject from June 1st to October 31th 1998 who had been hospitalized at Intensive Care Units in K medical center. A experimental group consists of 8 patients who were given proper positioning every two hours. A control group consists of 10 patients who were given traditional positioning. The collected data were analyzed by SPSS windows including $X^2$-test (Fisher's exact method), Wilcoxon Rank Sum test and McNemar test. The result of this study was summerized as follows : 1) The experimental group with proper positioning has shown lower shoulder pain score, dorsiflexion contracture score, Shoulder subluxation score and higher Range of Motion and than the control group. 2) The experimental group with proper positioning has shown lower muscle pain score and edema score than the control group, but it was not statistically significant.Therefore, proper positioning could be applied as an independent nursing intervent ion for patients on Stroke in order to facilitate rehabilitation.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.3
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• pp.95-104
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• 2017

Positioning signals transmitted by Global Positioning System (GPS) satellites located at approximately 20,000 km height is very weak. For the reason, GPS signals are vulnerable to intentional jamming and unintentional disturbance. Recently, the number of jamming has been increased significantly all over the world. For the applications where continuous and reliable positioning is required when GPS jammers are activated, other positioning systems are strongly required. In this work, a set of Time Division Multiple Access (TDMA)-based transmitters and receivers utilizing Universal Software Radio Peripheral (USRP) and GNU Radio are designed and implemented. To eliminate the undesirable effects of GPS jamming, a frequency band which does not overlap L band is utilized. To demonstrate the accuracy of the proposed method, an experiment was performed.