• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.31.3-31.3
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• 2008

Satellite laser ranging (SLR) system which measures the round trip time of laser to satellites is one of the important techniques in space geodesy. SLR system gives a powerful tool to determine the precise orbit of satellites, the center of mass of the Earth, and etc because it provides instantaneous range measurements of millimeter level precision. China Transportable Ranging Observation System (TROS) was built in 1999 and other four SLR stations were founded in China. TROS has been upgraded to the new electronic system capable of KHz ranging since last year, and succeeded in KHz SLR technology. TROS has been operated in KASI headquarter for research of space geodesy since August 2008, which will be operated for 12 months by August 2009. Now ISCEA and KASI keep strong relationship in SLR field.

• ETRI Journal
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• v.35 no.6
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• pp.1084-1093
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• 2013

problem of pedestrian localization using mobile nodes containing impulse radio ultra wideband (IR-UWB) is considered. IEEE 802.15.4a-based IR-UWB can achieve accurate ranging. However, the coverage is as short as 30 m, owing to the restricted transmit power. This factor may cause a poor geometric relationship among the mobile nodes and anchor nodes in certain environments. To localize a group of pedestrians accurately, an enhanced cooperative localization method is proposed. We describe a sequential algorithm and define problems that may occur in the implementation of the algorithm. To solve these problems, a batch algorithm is proposed. The batch algorithm can be carried out after performing the sequential algorithm to linearize the nonlinear range equation. When a sequential algorithm cannot be performed due to a poor geometric relationship among nodes, a batch algorithm can be carried out directly. Herein, Monte Carlo simulations are presented to illustrate the proposed method and verify its performance.

• The Journal of Korean Physical Therapy
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• v.25 no.4
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• pp.174-179
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• 2013

Purpose: Visual gait analysis plays a pivotal role in determining the important gait problem of patients. A few studies have been published and have received little attention regarding visual gait analysis on patients with orthopedic problems. The purposes of this study were to investigate the difference of reliability levels according to experience of clinical physical therapists. Methods: Thirty-five clinical physical therapists, 5 high experienced, 15 experienced, and 15 inexperienced, were recruited and individually evaluated these videotaped gait patterns of the participants, and filled up the structured gait analysis form. The gait of nine participants was videotaped. Reliability levels were calculated by the Intraclass Correlation Coefficients (ICC). Results: The inter-rater reliability of high experienced group (ICC=0.56; 95% CI: 0.50-0.62) was comparable to that of the experienced raters (ICC=0.48; 95% CI: 0.43-0.53) and inexperienced group (ICC=0.42; 95% CI: 0.38-0.46). High experienced group reached a higher inter-rater reliability level. The average intra-rater reliability of the high experienced group was 0.70 (ICCs ranging from 0.54 to 0.82). The experienced group reached an average intra-rater reliability of 0.61 (ICCs ranging from 0.47 to 0.81). The inexperienced group attained average ICC values of 0.53 (ICCs ranging from 0.30 to 0.74). Conclusion: Use of a structured gait analysis form as described in this study was found to be moderately reliable. Clinical experience appears to increase the reliability of visual gait analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.127-132
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• 2011

This paper proposes a ranging and communicating system that uses the UWB frequency slope modulated chirp signal. Instead of using only the up-chirp and down-chirp with the same frequency sweeping rate, the proposed system uses several chirps that have different frequency sweeping rates with frequency hopping. This system performs better than the conventional communication and ranging schemes because it is capable of increasing the data transmission rate and at the same time decreasing the interference between sequences used by users. In this paper, we propose simulations of UWB communication system to show validity by using the MATLAB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12B
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• pp.1244-1250
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• 2010

This paper presents a detection and ranging algorithm for a high-speed targets in the high PRF radar. We show, unlike the conventional methods, it firstly estimates Doppler frequency with a quasi-periodic pulse train prior to range processing. The estimated Doppler frequency can compensate the phase error enbeded in the received signal, which makes the signal integrated coherently in the range direction and localizes the target's signiture in low SNR. We present the derivation of the proposed algorithm and discuss how the system parameters such as the range/Doppler sampling condition, processing time and Doppler estimation error affect the performance of the proposed algorithm, which is verified by simulations.

• International Journal of Air-Conditioning and Refrigeration
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• v.14 no.4
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• pp.147-155
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• 2006

The drag reduction (DR) and heat transfer efficiency reduction (ER) of non-ionic surfactant were investigated as a function of fluid velocity, temperature, and surfactant concentration. An experimental apparatus consisting of two temperature controlled water storage tanks, pumps, test specimen pipe and the piping network, two flow meters, two pressure gauges, a heat exchanger, and data logging system was built. From the experimental results, it was concluded that existing alkyl ammonium surfactant (CTAC Cethyl Trimethyl Ammonium Chloride) had DR of $0.6{\sim}0.8$ at $1,000{\sim}2,000ppm$ concentration with fluid temperature ranging between $50{\sim}60^{\circ}C$. However, the DR was very low when the fluid temperature was $70{\sim}80^{\circ}C$. The new amine oxide and betaine surfactant(SAOB Stearyl Amine Oxide + Betaine) had lower DR at fluid temperatures ranging between $50{\sim}60^{\circ}C$ compared with CTAC. However, with fluid temperature ranging between $70{\sim}80^{\circ}C$ the DR was $0.6{\sim}0.8$ when the concentration level was $1,000{\sim}2,000ppm$.

• YAKHAK HOEJI
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• v.39 no.3
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• pp.314-328
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• 1995

This study was attempted to investigate the mechanism of retention of sodium and water by naproxen which is a drug among nonsteroidal anti-inflammatory drugs in dogs. Napoxen, when given intravenously in doses ranging from 30 mg to 100 mg/kg, elicited antidiuresis accompanied vath the decrease of osmolar clearance(Cosm) and amounts of sodium excreted in urine(E$_{Na}$), with the increase of sodium reabsorption rate in renal tubule(R$_{Na}$) and ratio of potassium against sodium (K/Na). Naproxen infused into a renal artery in doses ranging from 1.0mg to 3.0mg/kg/min produced both diuretic action in infused kidney and antidiuretic action in control kidney. Naproxen injected into carotid artery in doses ranging from 10.0 mg to 30.0 mg/kg exhibited antidiuretic action. Changes of renal function in the circumstances of above two antidiuresis were the same with aspect of intravenous naproxen. Antidiuretic action of naproxen injected into carotid artery was not affected by renal denervation, was blocked by pretreatment with i.v. arachidonic acid, prostaglandin precursor, or i.v. indomethacin, cyclooxygenase inhibitor. Naproxen injected into carotid artery abolished the diuretic action of i.v. spironolactone, aldosterone antagonist, and i.v. spironolactone blocked the antidiuretic action of naproxen given into carotid artery. The results suggest that naproxen produced antidiuresis, and sodium and water retention through the central system, the mechanism being related to the prostaglandin biosynthetic inhibition and aldostercfne like action.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.127-128
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• 2006

In this paper, we propose a novel signaling method using chirp signals in UWB radio with satisfaction of FCC regulation. Chirp signals have been used in many ranging systems such as radar because of its good correlation properties. Because it is important to use broader signal bandwidth in order to get higher precision of the ranging, according to the Cramer-Rao Lower Bound, UWB radio is extremely good as the ranging systems. But, it is very difficult to apply existing chirp signals to UWB, because FCC regulates that the systems operating in UWB radio must occupy signal bandwidth more than 500MHz on the condition of stopping the frequency sweeping. So, we propose multiple chirp signals which can satisfy the regulation of FCC while maintaining chirp signal's properties. The multiple chirp signals which are composed of the sub-chirps modulated by sub-carriers can expand the signal bandwidth with the same principle of OFDM systems. The simulation results show that the BER performance of the proposed multiple chirp signals is identical to that of conventional OFDM when it is applied to data communication, and that the correlation properties of the proposed signals are almost the same with properties as those of single chirp signals whose sweeping bandwidth is the same value with the proposed one.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.311-315
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• 2006

Precision location and positioning of Asset within a network is an attractive feature with various applications, especially in indoor environments. Such a demand is met by the standard task group, IEEE 802.15.4a. Several methods, that is, pulse, chirp and chaotic communications have been proposed so far to satisfy the requirements of the standard. Among them, ultra wideband direct chaotic communications has advantageous features such as low hardware complexity, low cost, lower power consumption and flexible frequency band plan. In this paper, the feasibility of the ranging system using non-coherent chaotic transceiver is investigated by designing and implementing the system and the performance is proved by conducting location experiments in real indoor environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.894-900
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• 2012

Indoor wireless positioning system uses ranging information of beacons in order to precisely estimate a tag location. To estimate distance between each beacons and tag, the system calculates arrival time of a tag pulse with clock of each beacon including independent clock offset. This clock offset seriously affects the performance of ranging and positioning. We propose in this paper a clock offset compensation method to solve this problem. To verify the performance of the proposed method, we simulated location estimation with random clock offset between -1,000ppm and 1,000ppm, and the result shows that the proposed scheme effectively solves the clock offset problem.