• Journal of Institute of Control, Robotics and Systems
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• v.19 no.6
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• pp.569-575
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• 2013

This paper proposes a method for PDR (Pedestrian Dead-Reckoning) using a low cost IMU. Generally, GPS has been widely used for localization of pedestrians. However, GPS is disabled in the indoor environment such as in buildings. To solve this problem, this research suggests the PDR scheme with an IMU attached to the pedestrian's waist. However, despite the fact many methods have been proposed to estimate the pedestrian's position, but their results are not sufficient. One of the most important factors to improve performance is, a new calibration method that has been proposed to obtain the reliable sensor data. In addition to this calibration, the PDR method is also proposed to detect steps, where estimation schemes of step length, attitude, and heading angles are developed. Peak and zero crossings are detected to count the steps from 3-axis acceleration values. For the estimation of step length, a nonlinear step model is adopted to take advantage of using one parameter. Complementary filter and zero angular velocity are utilized to estimate the attitude of the IMU module and to minimize the heading angle drift. To verify the effectiveness of this scheme, a real-time system is implemented and demonstrated. Experimental results show an accuracy of below 1% and below 3% in distance and position errors, respectively, which can be achievable using a high cost IMU.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.6
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• pp.30-38
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• 1998

In this paper, a new CMOS current-mode integrator is proposed that can apply the basic building block of the low-voltage high frequency current-mode active filter. And tuning circuits that control the gain and unity gain frequency of them is designed. The proposed integrator is composed of the CMOS complementary circuit which can extend transconductance of an integrator. Therefore, the unity gain frequency which is determined transconductance and MOSFET gate capacitance can be expanded by the proposed integrator. The unity gain frequency of the proposed integrator is increased about two times larger than that of the conventional continuous-time integrator with NMOS-gm. And also, cut-off frequency and gain of the active filter can be controlled with the designed tuning circuit. From the result, we can reduce errors on fabrication. And then, 3rd-order low-pass active filter is designed as an application circuits. These results are verified by the small signal analysis and the 0.8$\mu\textrm{m}$ parameter HSPICE simulation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.82-87
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• 2008

This paper presents a new fast locking dual-slope phase-locked loop. The conventional dual-slope phase-locked loop consists of two charge pumps and two phase-frequency detectors. In this paper, the dual-slope phase-locked loop was achieved with a charge pump and a phase-frequency detector as adjusting a current of the charge pump according to the phase difference. The proposed circuit was verified by HSPICE simulation with a $0.35{\mu}m$ CMOS standard process parameter. The phase locking time of the proposed dual-slope phase-locked loop was $2.2{\mu}s$ and that of the single-slope phase-locke loop was $7{\mu}s$.

• Biomedical Science Letters
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• v.7 no.4
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• pp.211-216
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• 2001

This studs was carried out to evaluate KBrO$_3$-induced acute toxicity by clinical pathological parameters in rats. Fourty rats were divided into 4 groups including normal group and three KBrO$_3$-treated groups with doses of 200, 300, and 400 mg/kg, p. o., respectively. Creatinine and BUN were increased remarkably by KBrO$_3$ at 400 mg/kg, respectively (p<0.05, p<0.01). Phosphorus content increased two times the control at 400 mg/kg (p<0.05). Osmolarity was increased, whereas $CO_2$ content showed decrease at 400 mg/kg, respectively (p<0.01, p<0.05). Histopathological findings also showed dose-dependent renal failure. On the other hand, AST was increased three times the control at 400 mg/kg (p<0.01). WBC was increased by KBrO$_3$ depending on the dosage. Platelet was decreased at 200 mg/kg, whereas it was increased at 400 mg/kg (p<0.05). The results above suggest that clinical pathological parameters could be used as indices for the evaluation of KBrO$_3$-induced acute toxic reponse occuring in not only kidney but other organs including liver, when the dosage is as high as 400 mg/kg.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.20 no.2
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• pp.51-65
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• 2016

Objectives This study was conducted to suggest a standard operating procedure (SOP) in order to improve the reliability of tongue-image analysis system. Methods An affecting-factors list was made, which may affect the diagnostic parameters of the tongue-image analysis system. They were sub-classified into two groups: controllable and uncontrollable. Only the controllable factors, which could affect the results and easily set-up, were included into the SOP draft. Affecting factors control experiment was performed to investigate the effects of controllable factors, whose influence on diagnostic parameters of the tongue-image analysis system is ambiguous: rehearsal for tongue extrusion; alignment of camera axis; and presentation of a guideline. Three subjects volunteered for this experiment. Each of three variables was implemented twice in a random order by two operators on the subjects. Finally, 96 tongue images obtained in the aggregate. The diagnostic parameter set as a primary outcome in this experiment was the percentage of tongue coating. Results All of the control variables were not significant in both operators; however, the presentation of a guideline was relatively more affect than two other variables. Interaction effects among the variables were also insignificant. Therefore, the presentation of a guideline was included in the final SOP and the other variables were not included. Conclusions We suggested the SOP which could be used for both experimenter and subject. Moreover, Each of the SOPs applied to various types of tongue-image analysis system should be developed in order to improve the reliability.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.4
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• pp.293-298
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• 2009

This paper presents a variable gain current control algorithm for the stabilized grid connection between the grid and a doubly fed induction(DFIG) as a wind power generator. The performance of a RSC current controller depends highly on accurate machine parameters, and especially requires a fast and robust response regardless of the disturbances such as voltage sag. However, parameter variations of a DFIG occur at the point of grid connection, which affects the current controller gains based on DFIG parameters after a DFIG is connected to the grid. Thus, performance degrades when actual machine parameters depart from values used in the control system. In the proposed algorithm, current controller gains of the rotor side converter(RSC) are changed after a DFIG is connected to the grid. The simulation results and experimental results for a 750kW are shown to illustrate the feasibility of the proposed algorithm.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.1
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• pp.80-87
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• 2010

The method of function synthesis is essential when we control the systems not known their characteristic, by predicting the function to satisfy a relation between input and output from the given pairs of input-output data. In general the most systems operate non-linearly, it is easy to come about problem is composed with combinations of parameter, constant, condition, and so on. Genetic programming is proposed by one of function synthesis methods. This is a search method of function tree to satisfy a relation between input and output, with appling genetic operation to function tree to convert function into tree structure. In this paper, we indicate problems of a function synthesis method by an existing genetic programming propose four type of new improved method. In other words, there are control of function tree growth, selection of local search method for early convergence, effective elimination of redundancy in function tree, and utilization of problem characteristic of object, for preventing function from complicating when the function tree is searched. In case of this improved method, we confirmed to obtain superior structure to function synthesis method by an existing genetic programming in a short period of time by means of computer simulation for the two-spirals problem.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.60-66
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• 2014

A control oriented model of the Lean $NO_x$ trap (LNT) was developed to determine the timing of $NO_x$ regeneration. The LNT model consists of $NO_x$ storage and reduction model. Once $NO_x$ is stored ($NO_x$ storage model), at the right timing $NO_x$ should be released and then reduced ($NO_x$ reduction model) with reductants on the catalyst active sites, called regeneration. The $NO_x$ storage model simulates the degree of stored $NO_x$ in the LNT. It is structured by an instantaneous $NO_x$ storage efficiency and the $NO_x$ storage capacity model. The $NO_x$ storge capacity model was modeled to have a Gaussian distribution with a function of exhaust gas temperature. $NO_x$ release and reduction reactions for the $NO_x$ reduction model were modeled as Arrhenius equations. The parameter identification was optimally performed by the data of the bench flow reactor test results at space velocity 50,000/hr, 80,000/hr, and temperature of $250-500^{\circ}C$. The LNT model state, storage fraction indicates the degree of stored $NO_x$ in the LNT and thus, the timing of the regeneration can be determined based on it. For practical purpose, this model will be verified more completely by engine test data which simulate the NEDC transient mode.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.6
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• pp.703-710
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• 2011

Odor emission from domestic sewer systems has become a serious environmental problem. An investigation on a sewer manhole revealed that anaerobic decay of sediment organic matters (SOMs) and related declines of oxidation reduction potential (ORP) in the sediment layer were the main reason of the production of volatile sulfur compounds. In addition, as the anaerobic decaying period continued, the odor intensity rapidly increased with increasing concentrations of $H_2S$ and dimethyl sulfide. As a feasible method to control SOMs and to minimize odor emission potentials, an electrolytic oxidation process has been employed to the sediment sludge phase. In this study, voltages applied to the electrolytic oxidation process were varied as a main system parameter, and its effects on odor removal efficiencies and reaction characteristics were investigated. At the applied voltages greater than 20 V, the system efficiently oxidized the organic matter, and the ORP in the sludge phase increased rapidly. As a consequence, the removal efficiency of hydrogen sulfide was found to be >99% within 60 minutes of the electrolytic oxidation. Overall, the electrolytic oxidation process can be an alternative to control odor emission from sewer systems, and a threshold input energy needs to be determined to achieve effective operation of the process.

• Journal of Preventive Medicine and Public Health
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• v.42 no.2
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• pp.135-142
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• 2009

Objectives : An appropriate sampling strategy for estimating an epidemiologic volume of diabetes has been evaluated through a simulation. Methods : We analyzed about 250 million medical insurance claims data submitted to the Health Insurance Review & Assessment Service with diabetes as principal or subsequent diagnoses, more than or equal to once per year, in 2003. The database was re-constructed to a 'patient-hospital profile' that had 3,676,164 cases, and then to a 'patient profile' that consisted of 2,412,082 observations. The patient profile data was then used to test the validity of a proposed sampling frame and methods of sampling to develop diabetic-related epidemiologic indices. Results : Simulation study showed that a use of a stratified two-stage cluster sampling design with a total sample size of 4,000 will provide an estimate of 57.04%(95% prediction range, 49.83 - 64.24%) for a treatment prescription rate of diabetes. The proposed sampling design consists, at first, stratifying the area of the nation into "metropolitan/city/county" and the types of hospital into "tertiary/secondary/primary/clinic" with a proportion of 5:10:10:75. Hospitals were then randomly selected within the strata as a primary sampling unit, followed by a random selection of patients within the hospitals as a secondly sampling unit. The difference between the estimate and the parameter value was projected to be less than 0.3%. Conclusions : The sampling scheme proposed will be applied to a subsequent nationwide field survey not only for estimating the epidemiologic volume of diabetes but also for assessing the present status of nationwide diabetes control.