• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.3
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• pp.13-21
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• 2007

A forklift is a motive machine powered by LPG, diesel engine or electric motors. The internal combustion engine type forklift is equipped with automatic transmission to meet the required drive load as well as the easy operation of the vehicle. This paper deals with the shift control and endurance test controller which is developed for the functional test of the newly designed automatic transmission on a dynamometer test bench. Its major function is to control the proportional solenoid currents, which is directly related to clutch pressures, for the given reference current trajectory during shift and sequential operation of shift schedule designed for the durability test at each gear. It also has the ability to monitor all the necessary test data through RS232 communication and log them to disk files. The current controller of embedded system is designed from the identified dynamics of solenoid coil and the current reference can be easily modified with a user interface software on PC so as to match the shift data by experiments.

• Journal of Sensor Science and Technology
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• v.26 no.4
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• pp.239-244
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• 2017

Noninvasive, cuffless, and continuous blood pressure (BP) monitoring is essential to prevent and control hypertension. A well-known existing method for this measurement is pulse transit time (PTT), which has been investigated by many researchers as a promising approach. However, the fundamental principle of the PTT method is based on the time interval taken by a pulse wave to propagate between the proximal and distal arterial sites. Consequently, this method needs an independent system with two devices placed at two different sites, which is a problem. Even though some studies attempted to synchronize the system, it is bulky and inconvenient by contemporary standards. To find a more sensitive method to be used in a BP measurement device, this study used radial electrical bioimpedance (REB) as a potential indicator for BP determination. Only one impedance plethysmography channel at the wrist is performed for demonstrating a ubiquitous BP wearable device. The experiment was evaluated on eight healthy subjects with the ambulatory BP monitor on the upper arm as a reference. The results demonstrated the potential of the proposed method by the correlation of estimated systolic (SBP) and diastolic (DBP) BP against the reference at $0.84{\pm}0.05$ and $0.83{\pm}0.05$, respectively. REB also tracked the DBP well with a root-mean-squared-error of $7.5{\pm}1.35mmHg$.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.11
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• pp.874-882
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• 2003

The condition assessment of engineering systems has increased in importance because the manpower needed to operate and supervise various plants has been reduced. Especially, induction motors are at the core of most engineering processes, and there is an indispensable need to monitor their health and performance. So detection and diagnosis of motor faults is a base to improve efficiency of the industrial plant. In this paper, a model-based fault detection system is developed for induction motors, using steady state vibration signals. Early various fault detection systems using vibration signals are a trivial method and those methods are prone to have missed fault or false alarms. The suggested motor fault detection system was developed using a model-based reference value. The stationary signal had been extracted from the non-stationary signal using a data segmentation method. The signal processing method applied in this research is FFT. A reference model with spectra signal is developed and then the residuals of the vibration signal are generated. The ratio of RMS values of vibration residuals is proposed as a fault indicator for detecting faults. The developed fault detection system is tested on 800 hp motor and it is shown to be effective for detecting faults in the air-gap eccentricities and broken rotor bars. The suggested system is shown to be effective for reducing missed faults and false alarms. Moreover, the suggested system has advantages in the automation of fault detection algorithms in a random signal system, and the reference model is not complicated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.9
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• pp.689-699
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• 2013

During extreme ionospheric storms, anomalous ionospheric delays and gradients could cause potential integrity threats to users of GNSS (Global Navigation Satellite System) augmentation systems. GNSS augmentation ground facilities must monitor these ionospheric anomalies defined by a threat model and alarm the users of safely-of-life applications within time-to-alerts. Because the ionospheric anomaly threat model is developed using data collected from GNSS reference stations, the use of poor-quality data can degrade the performance of the threat model. As the total number of stations increases, the number of station with poor GNSS data quality also increases. This paper analyzes the quality of data collected from Korean GPS reference stations using comprehensive GNSS data quality check algorithms. The results show that the range of good and poor qualities varies noticeably for each quality parameter. Especially erroneous ionospheric delay and gradients estimates are produced due to poor quality data. The results obtained in this study should be a basis for determining GPS data quality criteria in the development of ionospheric threat models.

• Progress in Medical Physics
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• v.2 no.1
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• pp.17-28
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• 1991

Generally, it is an accurate radiation measurement technique for processors fo thermoluminescent dosimenters(TLDs) to characterize each element they use by producing element correction factors(FCFs). TLDs are classified into three groups such as reference. control, and field TLDs. Reference TLDs are used only for the production of ECFs for the control and field TLDs. They are kept locked in a safe place except when it is necessary to use a subset of them to produce ECFs for the control and field TLDs. The ECF of a given element is a measure of the response of the element relative to the mean response of an arbitrarily selected group of reference elements. As TLDs are used in the field, their relative responses to radiation might be decreased due to muliple readings and physical abuse. Therefore, the producditon of ECFs are performed initially and periodically during the field use. This element correction method provides an excellent tool to examine new TLDs and to monitor the reliability of old TLDs. This paper discuss the 10 step procedures developed to produce and examine ECFs.

• Journal of Radiation Protection and Research
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• v.20 no.1
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• pp.37-44
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• 1995

Since provisions on the technical criteria for personnel dosimetry was amended three years ago, several improvements in the technique of monitoring personnel doses by TLD have taken place, but for the photograpfic film as a personnel monitor, additional investigations should be carried out for its accuracy of dose estimates because of its wide use in the radiation involved industries. So, this paper describes the methods to develope dose evaluation algorithm for photographic film using ISO reference radiations by i) empirical formula, ii) degree-of-fit method, and iii) matrix approximation. These methods show a good agreement between irradiated and calculated dose within tolerance level represented in ANSI N13. 11, and can be used for the dose evaluation of X, ${\gamma}$ and/or radiation fields.

• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.737-744
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• 2007

An isotope dilution-liquid chromatography/tandem mass spectrometric method was developed as a candidate reference method for the accurate determination of acrylamide in potato chips, starch-rich foodstuff cooked at high temperature. Sample was spiked with 13C3-acrylamide and then extracted with water. The extract was further cleaned up with an Oasis HLB solid-phase extraction (SPE) cartridge and an Oasis mixed-phase cation exchange (MCX) SPE cartridge. The extract was analyzed by using LC/ESI/Tandem MS in positive ion mode. LC with a medium reversed-phase (C4) column was optimized to obtain adequate chromatographic retention and separation of acrylamide. MS was operated to selectively monitor [M+H]+ ions of the analyte and its isotope analogue at m/z 72 and m/z 75, respectively. Sample was also analyzed by the LC/MS with selectively monitoring the collisionally induced dissociation channels of m/z 72 → m/z 55 and m/z 75 → 58. Compared to the LC/MS chromatograms, the LC/MS/MS chromatograms showed substantially reduced background chemical noises coming from solvent clusters formed during ESI spray processes and interferences from sample matrix. Repeatability and reproducibility studies showed that the LC/MS/MS method is a reliable and reproducible method which can provide a typical method precision of 1.0% while the LC/MS results are influenced by chemical interferences.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.1
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• pp.23-35
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• 2023

Korea Augmentation Satellite System (KASS) is a satellite-based augmentation system (SBAS) that provides approach procedure with vertical guidance-I (APV-I) level corrections and integrity information to Korea territory. KASS is used to monitor navigation performance in real-time, and this paper introduces the design, implementation, and verification process of mission monitoring (MIMO) in KASS. MIMO was developed in compliance with the Minimum Operational Performance Standards of the Radio Technical Commission for Aeronautics for Global Positioning System (GPS)/SBAS airborne equipment. In this study, the MIMO system was verified by comparing and analyzing the outputs of reference tools. Additionally, the definition and derivation method of accuracy, integrity, continuity, and availability subject to MIMO were examined. The internal and external interfaces and functions were then designed and implemented. The GPS data pre-processing was minimized during the implementation to evaluate the navigation performance experienced by general users. Subsequently, tests and verification methods were used to compare the obtained results based on reference tools. The test was performed using the KASS dataset, which included GPS and SBAS observations. The decoding performance of the developed MIMO was identical to that of the reference tools. Additionally, the navigation performance was verified by confirming the similarity in trends. As MIMO is a component of KASS used for real-time monitoring of the navigation performance of SBAS, the KASS operator can identify whether an abnormality exists in the navigation performance in real-time. Moreover, the preliminary identification of the abnormal point during the post-processing of data can improve operational efficiency.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.235-240
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• 2006

The paper will give an overview of the mission of GalTeC and then concentrate on two main aspects. The first more detailed aspect, is the analysis of the key performance parameters for the Galileo system services and presenting a technical overview of methods and algorithms used. The second more detailed aspect, is the service volume prediction including service dimensioning using the Prediction tool. In order to monitor and validate the Galileo SIS performance for Open Service (OS) and Safety Of Life services (SOL) regarding the key performance parameters, different analyses in the SIS domain and User domain are considered. In the SIS domain, the validation of Signal-in-Space Accuracy SISA and Signal-in-Space Monitoring Accuracy SISMA is performed. For this purpose first of all an independent OD&TS and Integrity determination and processing software is developed to generate the key reference performance parameters named as SISRE (Signal In Space Reference Errors) and related over-bounding statistical information SISRA (Signal In Space Reference Accuracy) based on raw measurements from independent sites (e.g. IGS), Galileo Ground Sensor Stations (GSS) or an own regional monitoring network. Secondly, the differences of orbits and satellite clock corrections between Galileo broadcast ephemeris and the precise reference ephemeris generated by GalTeC will also be compared to check the SIS accuracy. Thirdly, in the user domain, SIS based navigation solution PVT on reference sites using Galileo broadcast ephemeris and the precise ephemeris generated by GalTeC are also used to check key performance parameters. In order to demonstrate the GalTeC performance and the methods mentioned above, the paper presents an initial test result using GPS raw data and GPS broadcast ephemeris. In the tests, some Galileo typical performance parameters are used for GPS system. For example, the maximum URA for one day for one GPS satellite from GPS broadcast ephemeris is used as substitution of SISA to check GPS ephemeris accuracy. Using GalTeC OD&TS and GPS raw data from IGS reference sites, a 10 cm-level of precise orbit determination can be reached. Based on these precise GPS orbits from GalTeC, monitoring and validation of GPS performance can be achieved with a high confidence level. It can be concluded that one of the GalTeC missions is to provide the capability to assess Galileo and general GNSS performance and prediction methods based on a regional and global monitoring networks. Some capability, of which first results are shown in the paper, will be demonstrated further during the planned Galileo IOV phase, the Full Galileo constellation phase and for the different services particularly the Open Services and the Safety Of Life services based on the Galileo Integrity concept.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.81-90
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• 1999

This paper describes an EEG(electroencephalogram) software for two-channel cerebral function monitoring system to detect the cerebral ischemia. In the software, two-channel bipolar analog EEG signals are digitized and from the signals various EEG parameters are extracted and displayed on a monitor in real-time. Digitized EEG signal is transformed by FFT(Fast Fourier transform) and represented as CSA(compressed spectral array) and DSA(density spectral array). Additional 5 parameters, such as alpha ratio, percent delta, spectral edge frequency, total power, and difference in total power, are estimated using the FFT spectra. All of these are effectively merged in a monitor and displayed in real-time. Through animal experiments and clinical trials on men, the software is modified and enhanced. Since the software provides raw EEG, CSA, DSA, simultaneously with additional 5 parameters in a monitor, it is possible to observe patients multilaterally. For easy comparison of patient's status, reference patterns of CSA, DSA can be captured and displayed on top of the monitor. And user can mark events of surgical operation and patient's conditions on the software, this allow him jump to the points of events directly, when reviewing the recorded EEG file afterwards. Other functions, such as forward/backward jump, gain control, file management are equipped and these are operated by simple mouse click. Clinical tests in a university hospital show that the software responds accurately according to the conditions of patients and medical doctors can use the software easily.