• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.1
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• pp.35-41
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• 2000

This paper considers the consturction of 24/25 I-NRZI (Interleaved - Non Return to Zero Inverse) modulator designs for DVCR (Digital Video Cassette Recorder), and size of validity bit in order to store the amplitude value of square-wave and the standard data ( sine and cosine coefficients) at ROM Table that to acceptable the spectrum standard. The validity bit size of the standard data and the amplitude value of square-wave that to store at ROM Table are affected the size of pilot signal on the output spectrum, and the hardware size of modulator. At the designable 24/25 I-NRZI modulator, we simulated using random pattern (F0,F1,F2) that to verification the output data of the spectrum. Moreover, the resultant of the spectrum analysis, at the optimizing value, is 0.065 on the amplitude value of square-wave, and 3bit on the size of bit in order to store the standared data at ROM Table. In order to verify the hardware of designable 24/25 I-NRZI modulator, we perform to modeling of C-language firstly, and coding to Verilog HDL (Cadence Verilog XL) and synthesized using Synopsys (Library "Samsung KG75") tool as a base of spectrum results. In a foundation of this result, we are considered the size of hardware. In this paper, a considerable 24/25 I-NRZI modulator designable less than 10,000 gates as that is improved consturction as regards the path method of pre-coder etc, and able to application digital camcorders as now practical use.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.345-352
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• 2017

In this paper, a unified potentiostat which can measure the current of both $O_2$-based and $H_2O_2$-based blood glucose sensors with low supply voltage of 1.0V has been designed and verified by simulations and measurements. Potentiostat is composed of low-voltage operational transconductance amplifier, cascode current mirrors and mode-selection circuits. It can measure currents of blood glucose chemical reactions occurred by $O_2$ or $H_2O_2$. The body of PMOS input differentional stage of the operational transconductance amplifier is forward-biased to reduce the threshold voltage for low supply voltage operation. Also, cascode current mirror is used to reduce current measurement error generated by channel length modulation effects. The proposed low-voltage potentiostat is designed and simulated using Cadence SPECTRE and fabricated in Magnachip 0.18um CMOS technology with chip size of $110{\mu}m{\times}60{\mu}m$. The measurement results show that consumption current is maximum $46{\mu}A$ at supply voltage of 1.0V. Using the persian potassium($K_3Fe(CN)_6$) equivalent to glucose, the operation of the fabricated potentiostat was confirmed.

• 한국체육학회지인문사회과학편
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• v.57 no.6
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• pp.263-272
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• 2018

This study examined the association of gait variability and physical fitness with frailty status in older women. In a cross-sectional design, 168 elderly women, aged 65 years and older (75.07±5.40 years), measured body composition, gait parameters gait variability, physical fitness variables, MMSE-DS and CES-D. Subjects were classified as robust, pre-frail, and frailty based on the Fried et al.(2001) criteria for frailty weight loss, exhaustion, low hand-grip strength, low gait speed, and physical inactivity. Logistic regression analyses were used to determine the odds ratio (ORs) and 95% confidence interval (CI) of frailty status for having gait variability and physical fitness levels. Compared to the robust group (OR=1), the frailty group had significantly higher ORs of having terminal double limb stance (OR=1.48, 95% CI=0.10-2.21, p=.049), step cadence (OR=2.06, 95%CI=1.20-3.43, p=.009) variability, and significantly lower ORs of having upper-strength (OR=0.49, 95%CI=0.31-0.77, p=.002) even after adjusting for age, education, comorbidity, K-IADL, MMSE-KC and CES-D score. The finding of this study suggested that terminal double limb stance, step cadence and upper body muscular strength were independent predictors of frailty.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2D
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• pp.217-225
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• 2008

Bus stop is necessary to improve user-focused environment to offer convenient service because of the large number of passengers. This study is to analyze user's evaluation and establishment model of the service levels at bus stop using GAP analysis, IPA and Structural equation model and suggests improvement direction of bus stop. In the GAP analysis, on thirty-one service items of bus stop, the difference appeared highly from the items such as obstacle's facility and the information related to the using bus. In the current IPA service bus operation information, cadence facility and obstacle support facility need to be improved. And in service expectation bus operation information and th exchange facility, the obstacle support facility need to be improved continuously. The evaluation model of bus stop service due to a structure equation's was fitted well by structure equation. In overall satisfaction on bus stop, the waiting satisfaction is more affect the satisfaction of bus use facility. Satisfaction in bus use facility, the related information of bus operation, cadence facility, bus operation information and trans facility, obstacle support facility is more affect compare to other items. The lower overall satisfaction in bus stop is the higher the expectation of overall satisfaction is. Therefore, the information of bus operation and the support facility for the handicapped needs an active improvement plan than ever.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.593-600
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• 2010

In this paper, High brightness LED (light-emitting diodes) driver IC (integrated circuit) using new current sensing circuit is proposed. This LED driver IC can provide a constant current with high current precision over a wide input voltage range. The proposed current-sensing circuit is composed of a cascode current sensor and a current comparator with only one reference voltage. This IC minimizes the voltage stress of the MOSFET (metal oxide semiconductor field effect transistor) from the maximum input voltage and has low power consumption and chip area by using simple-structured comparator and minimum bias current. To confirm the functioning and characteristics of our proposed LED driver IC, we designed a buck converter. The LED current ripple of the designed IC is in ${\pm}5%$ and a tolerance of the average LED current is lower than 2.43%. This shows much improved feature than the previous method. Also, protections for input voltage and operating temperature are designed to improve the reliability of the designed IC. Designed LED driver IC uses 1.0 ${\mu}m$ X-Fab. BiCMOS process parameters and electrical characteristics and functioning are verified by spectre (Cadence) simulation.

• Korean Journal of Applied Biomechanics
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• v.21 no.4
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• pp.459-466
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• 2011

The purpose of this study was to analyze of obstacle gait using spatio-temporal and foot pressure variables in children with autism. Fifteen children with autism and fifteen age-matched controls participated in the study. Spatio-temporal and foot pressure variables was investigated using GAITRite pressure sensor system. Each footprint was divided into 12 equal trapezoids and after that the hindfoot, midfoot and forefoot analysis was developed. Independent t-test was applied to compare the gait variables between the groups. The results showed that the autism group were significantly decreased in velocity, cadence, cycle and swing time compared to the control group. The autism group were significantly increased in step width and toe out angle compared to the control group. The autism group were significantly increased at midfoot and forefoot of lateral part of footprint and forefoot of medial part of footprint in the peak time compared to the control group. The autism group were significantly increased at midfoot and hindfoot in $P^*t$, at midfoot in active area, and at hindfoot in peak pressure compared to the control group. In conclusion, the children with autism showed abnormal obstacle gait characteristics due to muscle hypotonia, muscle rigidity, akinesia, bradykinesia and postural control impairments.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.82.2-82.2
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• 2015

In this talk, we introduce the Lee Sang Gak Telescope (LSGT), a 0.43m telescope that can be operated remotely. This telescope was installed at the Siding Spring Observatory in 2015 October, and since then, it has been operated through a robotic reservation system, remotely from Korea. This telescope is now being used for educational and research activities of SNU Astronomy program. By placing the telescope at a place with an excellent astro-climate in Australia, the observation class activity can include objects in the southern hemisphere to the magnitude limit of V=20 mag at an exposure time of a few minutes. For example, Cepheid stars in Magellanic clouds can be observed during a class activity for constructing the classical Cepheid light curves that has been a key distance measure technique. Research activities such as transient observation and monitoring observation of AGN are possible, and we are currently running a high cadence supernovae search program by monitoring nearby galaxies intensively (see a presentation by C. Choi). The installation of the telescope was made possible from a support from the Seoul.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.3
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• pp.351-360
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• 2013

PURPOSE: The purpose of this study was to investigate the effects of observed action gait training on stroke patients. METHODS: 22 subjects were randomized into two groups. The observed action gait training performed that watched a video of normal gait before gait training and the general gait training without watching it. The experimental group(n=11) performed observed action gait training and the control group(n=11) performed general gait training. Both group received gait training for 3 times per week during 8 weeks. RESULTS: The experimental group showed significant differences in the cadence, gait velocity, stride, step, single limb support, double limb support, stride length and step length(p<.05). The control group showed significant differences only in the stride(p<.05). CONCLUSION: The observed action gait training affected coordination and weight shift, as well as symmetry of the body. Plasticity of the brain was facilitated by repetitive visual and sensory stimulation. The observed action gait training promoted the normal gait by watching the normal gait pattern. In conclusion, motor learning through the sensory stimulation promotes brain plasticity that could improve motor function, and observed action gait training indirectly identified stimulated brain activities.

• Physical Therapy Rehabilitation Science
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• v.2 no.2
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• pp.81-86
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• 2013

Objective: The objective of this study was to investigate the feasibility and effects of balance training using a newly developed elastic band orthosis (aider) for improvement of mobility and balance in chronic stroke patients. Design: Cross-sectional study. Methods: Ten patients with chronic hemiplegia participated in this study. There were six males and four females; two patients had right hemiplegia and eight had left hemiplegia. This study investigated the effect of the elastic band orthosis on balance and gait ability compared with bare foot condition. Gait parameters were measured using the opto-gait system for analysis of the spatial and temporal parameters of walking in stroke patients. In addition, balance ability in stroke patients was evaluated using the Timed Up and Go (TUG) and Berg Balance Scale (BBS). Results: This study investigated the effect of the elastic band orthosis on balance compared with bare foot condition. The TUG and BBS showed significant improvement with use of the elastic band orthosis (p<0.05). Use of the Elastic band orthosis resulted in significantly improved velocity, cadence, less-affected step length, less-affected stride length, and less-affected single limb support in stroke patients (p<0.05). Conclusions: We demonstrated a significant improvement in dynamic balance and gait ability in chronic stroke patients using the elastic band orthosis. This orthosis may aid in prevention of spastic foot drop, leading to improvement of walking ability.

• ETRI Journal
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• v.42 no.1
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• pp.46-53
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• 2020

Gait analysis is an effective clinical tool across a wide range of applications. Recently, inertial measurement units have been extensively utilized for gait analysis. Effective gait analyses require good estimates of heel-strike and toe-off events. Previous studies have focused on the effective device position and type of triaxis direction to detect gait events. This study proposes an effective heel-strike and toe-off detection algorithm using a smart insole with inertial measurement units. This method detects heel-strike and toe-off events through a time-frequency analysis by limiting the range. To assess its performance, gait data for seven healthy male subjects during walking and running were acquired. The proposed heel-strike and toe-off detection algorithm yielded the largest error of 0.03 seconds for running toe-off events, and an average of 0-0.01 seconds for other gait tests. Novel gait analyses could be conducted without suffering from space limitations because gait parameters such as the cadence, stance phase time, swing phase time, single-support time, and double-support time can all be estimated using the proposed heel-strike and toe-off detection algorithm.