• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.10-14
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• 1987

Considering transition gating of the input unipolar NRZ signal, the equivalent linear time-invariant model has been derived for the PLL in the timing clock recovery circuits. The magnitude of the alignment and accumulated jitter has been found along a chain of repeaters. For the timing recovery circuit of 90 Mbps optical communication system, the computer simulation shows that, for the first stage of the chain, the alignment jiter and the accumulated jitter are of -5.1766 dB and for the 7-th stage, the alignment jitter and accumulated jitter have the value of -1.0193dB, 4.9053 dB respectively.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.481-490
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• 2008

Reaction wheel is one of the actuators for spacecraft attitude control, which generates torque by changing an inertial rotor speed inside of the wheel. In order to generate required torque accurately and estimate an accurate angular momentum, wheel speed should be measured as close to the actual speed as possible. In this study, two conventional speed detection methods for high speed motor with digital tacho pulse (Elapsed-time method and Pulse-count method) and their resolutions are analyzed. For satellite attitude maneuvering and control, reaction wheel shall be operated in bi directional and low speed operation is sometimes needed for emergency case. Thus the bias error at low speed with constant acceleration (or deceleration) is also analysed. As a result, the speed detection error of elapsed-time method is largely influenced upon the high-speed clock frequency at high speed and largely effected on the number of tacho pulses used in elapsed time calculation at low speed, respectively.

• Journal of the Korea Convergence Society
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• v.9 no.5
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• pp.7-14
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• 2018

The purpose of this study is to analyze the effect of commuter's departure time on transportation system in future traffic system operated autonomous vehicle using agent based model. Various scenarios have been set up, such as when all passenger choose a similar departure time, or if the passenger chooses a different departure time. Also, this study tried to analyze the effect of road capacity. It was found that although many of the scenarios had been completed in a stable manner, many commuters were significantly coordinated at the desired departure time. In particular, in the case of a reduction in road capacity or in certain scenarios, it has been shown that, despite excessive schedule adjustments, many passengers are unable to commute before 9 o'clock. As a result, it is suggested that traffic management and pricing policies are different from current ones in the era of autonomous car operation.

• Sleep Medicine and Psychophysiology
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• v.3 no.2
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• pp.18-31
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• 1996

Jet-lag can be defined as the cumulative physiological and psychological effects of rapid air travel across multiple time zones. Many reports have suggested that age-related changes in sleep reflect fundamental changes in the circadian system and in significant declines in slow wave sleep. Jet lag is a dramatic situation in which the changes of the phase of circadian process and homeostatic process of sleep occur. Thus the authors evaluatead the changes of sleep-wake cycle from jet lag by age. Thirty-eight healthy travellers were studied for 3 days before and 7 days after jet-flights across seven to ten time zone. They were aged 19-70, They trareled eastbound, Seoul to North America (USA, Canada). Sleep onset time, wake-up time, sleep latency, awakening frequency on night sleep, awakening duration on night sleep, sleepiness at wake-up and nap length were evaluated. Our results suggest that by the 7 to 10 time zone shift, the old age group was significantly influenced in sleep-wake cycles. The date on which subjective physical condition was recovered was $6.23{\pm}83$ day after arrivals for old age group, while for young and middle age group, $4.46{\pm}1.50$ day and $4.83{\pm}1.52$ day, respectively. In old age group, sleep onset time was later than baselines and could not recover untill 7th day. But in other groups, the recovery was within 5th day. Nap dura fion was longer in old age group through jet lag than younger age group. In other parameters, there was no definite difference among three age groups. Our results suggested that the old age was significantly influenced by the disharmony between internal body clock and sleep-wake cycle needed at the travel site. Thus we proved that recovery ability from jet lag was age-dependent as well as travelling direction-dependent. To demonstrate more definite evidence, EEG monitoring and staging of sleep were funthun encouraged.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.12
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• pp.70-78
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• 2000

A novel capacitance deviation-to-time interval converter based on ramp-integration is presented. It consists of two current mirrors, two schmitt triggers, and control digital circuits by the upper and lower sides, symmetrically. Total circuit has been with discrete components. The results show that the proposed converter has a linearity error of less than 1% at the time interval(pulse width) over a capacitance deviation from 295 pF to 375 pF. A capacitance deviation of 40pF and time interval of 0.2 ms was measured for sensor capacitance of 335 pF. Therefore, the high-resolution can be known by counting the fast and stable clock pulses gated into a counter for time interval. The application of a novel capacitance deviation-to time interval converter to a digital humidity controller is also presented. The presented circuit is insensitive to the capacitance difference in disregard of voltage source or temperature deviation. Besides the accuracy, it features the small MOS device count integrable onto a small chip area. The circuit is thus particularly suitable for the on-chip interface.

• Women's Health Nursing
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• v.4 no.3
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• pp.322-331
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• 1998

The postpartum is a period of transition to motherhood where a childless woman transforms into a woman with children. Parents, especially mothers must perform an essential role of implementing instrumental and emotional care behaviors on part of the helpless, dependent, and immature infant. First-time mothers, however, suddenly face the responsibility of round the clock duty without neither parenting training during pregnancy, nor a time to gradually adapt to growing responsibilities after birth, with confusion and frustration as a result. Thus, after providing first-time mothers with childcare education as maternal role preparation, this study will try to examine its effects on childcare behaviors and confidence in maternal role during the early postpartum period. This quasi-experimental study using a nonequivalent control group non-synchronized design, was carried out from March 1995 to May 1996 to verify the effects of a childcare education program with first-time mothers who had vaginal delivery in Ewha University Hospital, Seoul, Korea, and collected data from 60 subjects who consented to the study. The education was given in the early postpartum period(48-72 hours after delivery) and to measure its effects, a posttest was done 4 weeks later with the results analyzed by SPSS shown in the following : 1. The childcare behavior score of the experimental group that had received the newborn care education was higher than the control group(t=3.5, P=.001). 2. The control group and the experimental group which had received the education showed no difference in degree of confidence in maternal role. 3. The higher the childcare behavior score, the higher the degree of confidence in maternal role was among the subjects(r=.56, P=.001). The preceding results are significant in that childcare practices can be promoted by providing child-care education to first-time mothers in the early postpartum period. Thus, this education can be used as a nursing intervention strategy in the early postpartum period.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.8
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• pp.239-244
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• 2015

WebCL was proposed for high complex computing in Javascript. Since WebCL-based applications are distributed and executed on an unspecified number of general clients, it is important to profile their performances on different clients. Several profilers have been introduced to support various programming languages but WebCL profiler has not been developed yet. In this paper, we present a WebCL profiler to evaluate WebCL-based applications and monitor the status of GPU on which they run. This profiler helps developers know the execution time of applications, memory read/write time, GPU statues such as its power consumption, temperature, and clock speed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.3208-3229
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• 2017

Rectification is an essential procedure for simplifying the disparity extraction of stereo matching algorithms by removing vertical mismatches between left and right images. To support real-time stereo matching, studies have introduced several look-up table (LUT)- and computational logic (CL)-based rectification approaches. However, to support high-resolution images, the LUT-based approach requires considerable memory resources, and the CL-based approach requires numerous hardware resources for its circuit implementation. Thus, this paper proposes a multi-level accumulation-based rectification method as a simple CL-based method and its circuit implementation. The proposed method, which includes distortion correction, reduces addition operations by 29%, and removes multiplication operations by replacing the complex matrix computations and high-degree polynomial calculations of the conventional rectification with simple multi-level accumulations. The proposed rectification circuit can rectify $1,280{\times}720$ stereo images at a frame rate of 135 fps at a clock frequency of 125 MHz. Because the circuit is fully pipelined, it continuously generates a pair of left and right rectified pixels every cycle after 13-cycle latency plus initial image buffering time. Experimental results show that the proposed method requires significantly fewer hardware resources than the conventional method while the differences between the results of the proposed and conventional full rectifications are negligible.

• Korean Journal of Occupational Health Nursing
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• v.24 no.1
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• pp.39-47
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• 2015

Purpose: This study is performed to help manage the metabolic syndrome in work place by identifying the effect on metabolic syndrome with subjects of Korean adult workers. Methods: Using part of data of "The Fourth Korean National Health and Nutrition Examination survey 2nd year (2008)" which center for disease control is investigating. The general characteristics include age, educational level, occupation and marital status as factors affecting the metabolic syndrome of workers in this study. Results: Work-related factors are the working environment in which they are working while they are pressed for time due to work status and overload. If the work status of worker is unpaid family member, the risk is increased by more than twice compared to paid workers. The risk for metabolic syndrome in work environment to work while fighting the clock is decreased compared to the work environment without time pressure. Conclusion: In order to manage the metabolic syndrome of workers, health promotion program to change management of both working condition and working environment can contribute to prevent the metabolic syndrome and ultimately prevent the cerebrocardiovascular diseases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4159-4164
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• 2012

This paper presents a chaotic circuit with voltage controllability for secure communication applications. The proposed circuit which has two control voltages consists of the nonlinear function block(NFB) with three MOS transistors, one source follower and non-overlapping two-phase clock generator for sample and hold. By SPICE simulation, chaotic dynamics such as time waveform, frequency analysis and bifurcations were analyzed. SPICE results showed that proposed circuit can make various chaotic signals by control voltage.