• Sleep Medicine and Psychophysiology
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• v.4 no.2
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• pp.191-200
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• 1997

Objectives : Periodic limb movements during sleep (PLMS) may cause arousals that may lead to non-restorative sleep. PLMS is characterized by long sleep latency, sleep fragmentation, frequent stage shifts, and rarity of stages 3/4 NREM sleep on polysomnography. However, controversies have existed and it still remains to be elaborated whether PLMS actually causes insomnia, since normal persons happen to have PLMS. Clinically, it would be crucial to know factors which might disturb sleep in PLMS. We became interested in Coleman's theory(1980) that invariant periodic movements disturb patients' sleep less. Though, Coleman's study seems to have been confounded by including PLMS patients with various co-morbid sleep disorders. Therefore, we attempted to study in patients only with PLMS the effects of movement patterns on sleep architecture. Methods : In 27 patients diagnosed as having PLMS only with clinical interview and nocturnal polysomnography, we studied the relationship between the movement patterns such as mean duration and variability of periodic limb movement's interval and the sleep architecture variables. Results : The shorter and the more regular the limb movement intervals were, the fewer arousals followed. The movement intervals of the older patients were shorter and more regular than the younger patients. The probability of the accompanying arousal with each limb movement increased as the duration and variance of the movement intervals increased. It decreased as the age and the frequency of limb movements increased. Among these factors the most significant one was the mean duration of the movement intervals. In other words, the shorter the movement intervals were, the less disturbed sleep was. Conclusion : PLMS frequency increases with aging but the probability of the accompanying arousal with each movement decreases with aging. Sleep-disturbing effects of PLMS depends more on the duration and variability of movement intervals than the PLMS frequency.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.221-226
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• 2010

Quartz crystal microbalance (QCM) gas sensor to detect methyl mercaptan ($CH_3SH$) gas was fabricated by depositing $TiO_2$ nanoparticles and polyelectrolyte on the electrode of QCM. The $TiO_2$/poly(sodium 4-styrenesulfonate) (PSS) thin film fabricated by a layer-by-layer self-assembly (LBL-SA) method showed a high surface area and increased the sensitivity of gas sensor. When the QCM sensors coated with triethanolamine (TEA) or ($TiO_2$/PSS) were exposed to methyl mercaptan gas (1.0 ppm), the frequency shifts of QCM with TEA casting film and $TiO_2$/PSS thin film were ca. 9 Hz and ca. 24 Hz, respectively. As the bilayer number of ($TiO_2$/PSS) increased, the frequency shift of QCM sensor with ($TiO_2$/PSS) thin film was gradually increased. In addition, the frequency shift of QCM sensor was gradually increased as the concentration of methyl mercaptan gas increased from 0.5 ppm to 2.0 ppm. In this study, the surface morphology and sensor property of QCM sensor coated with ($TiO_2$/PSS) thin film were measured.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.245-251
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• 2015

In this paper, we present a design of PWM-controlled driving device for backlights in LED systems. The system can control either the brightness of the entire screen of backlights of LCD driven by LED or illumination or contrast of each partial segment of the entire screen. The PWM-controlled driving device includes the shift register that shifts the series data according to the clock signal prior to the generation of parallel data. It is also is comprised of a number of registers, a number of counters, a number of comparators, and a number of synchronizing gates (producing the PWM-controlled signals). The proposed device for backlights in LED systems can generate the PWM-controlled signal with a high degree of resolution without the increase of clock frequency. It also contains the PWM-controlled circuit that disperses and restrains the quantized noise.

• Journal of Korean Academy of Nursing Administration
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• v.22 no.5
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• pp.531-539
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• 2016

Purpose: This study was done to investigate new graduate nurses' perceptions of nursing professionalism, job involvement and turnover intention and to identify factors influencing turnover intention in new graduate nurses. Methods: Participants were 179 new graduate nurses working in general hospitals and small and medium-sized hospitals in Gyungnam province. Data were collected from August 10 to September 16, 2015 through a survey with self-report questionnaires. Data were analyzed using descriptive statistics, t-test, ANOVA, $Scheff{\acute{e}}$ test, Pearson correlation coefficients, and multiple regression analysis. Results: Mean scores were; for nursing professionalism, $3.62{\pm}0.73$, for job commitment, $3.22{\pm}0.89$. and for turnover intention, $3.25{\pm}0.95$. There were significant correlations between nursing professionalism and job involvement (r=.47, p<.001), nursing professionalism and turnover intention (r=-.36, p<.001), job involvement and turnover intention (r=-.46, p<.001). For turnover intention of new graduates 25.1% of the variance was explained by nursing professionalism (${\beta}=-.16$, p=.034), job involvement (${\beta}=-.36$, p<.001), and frequency of night shifts (${\beta}=.03$, p=.022). Conclusions: Findings indicate that nursing professionalism and job involvement of new graduate nurses had significant influence on their turnover intention. Therefore, to reduce turnover intention of new graduate nurses, it is necessary to enhance their nursing professionalism and job involvement with organizational supports.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.142-145
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• 2005

Since the successful launch of FORMOSAT -2 satellite by National Space Organization of Taiwan in May 2004, the Remote Sensing Instrument (RSI) on- board the FORMOSAT -2 has continuously acquired images at one panchromatic and four multi-spectral bands (http://www.nspo.org.tw). In general, the RSI performs well and receives high quality images which proved to be very useful for various applications. However, some RSI panchromatic products exhibit obvious trembling artifact that must be removed. Preliminary study reveals that the trembling artifact is caused by the instability of the spacecraft attitude. Though the magnitude of this artifact is actually less than half of a pixel, it affects the applicability of panchromatic products. A procedure removing this artifact is therefore needed for providing image products of consistent quality. Due to the nature of trembling artifact, it is impossible to describe the trembling amount by employing an analytic model. Relied only on image itself, an algorithm determining trembling amount and removing accordingly the trembling artifact is proposed. The algorithm consists of 3 stages. First, a cross-correlation based scheme is used to measure the relative shift between adjacent scan lines. Follows, the trembling amount is estimated from the measured value. For this purpose, the Fourier transform is utilized to characterize random shifts in frequency domain. An adaptive estimation method is then applied to deduce the approximate trembling amount. In the subsequent stage, image re-sampling operation is applied to restore the trembling-free product. Experimental results show that by applying the proposed algorithm, the unpleasant trembling artifact is no longer evident.

• Journal of the Korean Magnetic Resonance Society
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• v.11 no.2
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• pp.64-72
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• 2007

[ $^1H$ ] nuclear magnetic resonance (NMR) experiments have been performed at 30 - 300 K and 7 T to investigate dynamics of hydrogen bond network in the single crystal $(NH_4)_3H(SO_4)_2$. The two proton sites, ammonium proton and hydrogen-bond proton, are identified from the $^1H$ NMR MAS spectrum at 340 K. As temperature decreases, the $^1H$ NMR spectrum shifts to the higher frequency side with a larger linewidth. The spectrum at 65 K shows a distinctive change in line shape toward the ferroelectric transition at 63 K. The measured values of $T_1$ for ammonium and hydrogen-bond protons are similar in the whole range of temperature. $T_1$ of $^1H$ NMR shows a gradual decrease down to 120 K and starts to steeply increase below 100 K. Then $T_1$ shows abrupt decrease below 70 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. This temperature dependence of spectrum and $T_1$ clearly prove that the large change in the dynamics of hydrogen bond network is associated with the ferroelectric phase transition at 63 K.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1292-1296
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• 2002

In this paper, a 3-coupled microstrip line tunable bandpass filter has been designed on the basis of a tonductoriFerroelectricfDielectric (CFD) structure. This tunable filter basically exploits the fact that the increase in the bias voltage leads to the reduction of the effective dielectric constant (eon). This reduced $\varepsilon$eff shifts the center frequency (fc) to the higher value. The characteristics of designed filter are as follows; Return loss (RL) is larger than 10 dB; Insertion loss (IL) is les.i than 3.5 dB: 3-dB bandwidth (BW) is less than 1.18 GHz fc can be tuned from 25.4 GHz to 28.8 GHz over the variation of $\varepsilon$eff, from 10 to 13. Therefore, the tunability comes up to 3.4 GHz. The dimension of the filter designed is 7.0 mm ${\times}$ 5.0 nm ${\times}$ 0.5 mm.

• Korean Journal of Occupational Health Nursing
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• v.16 no.1
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• pp.37-47
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• 2007

Purpose: To find out the relationship between the shift work, and disrupted sleep and consequent fatigue symptoms. Methods: The questionnaires were given to 345 nurses of 4 hospitals with over 400 beds in Daejeon. Results: The shift workers showed worse subjective quality of sleep than the daytime workers, and had significantly higher frequency of "cannot get to sleep within 30 minutes", "wake up in the middle of the night" and "wake up in the early morning". The shift workers had significantly higher scores of subjective symptoms of fatigue than the daytime workers, and the fatigue was found to be the mental type. The subjective symptoms of fatigue scores were significantly higher in the group who had "cannot get to sleep within 30 minutes", "wake up in the middle of the night" and "wake up in the early morning". Conclusion: The study results indicated that the shift workers had the higher level of subjective symptoms of physical fatigue as well as the worse quality of sleep than the daytime workers. It is speculated that the factors attributable to the poor quality of sleep or sleep induction disorders of nurses of hospitals could be due in major part to adaptational difficulties resulting from frequent night shifts.

• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.185-192
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• 2004

The aeroacoustic characteristics of a centrifugal fan for a vacuum cleaner and its noise reduction method are studied in this paper. The major noise source of a vacuum cleaner is the centrifugal fan. The impeller of the fan rotates at over 30000 rpm, and generates very high-level noise. It was revealed that the dominant noise source is the aerodynamic interaction between the rotating impeller and stationary diffuser. The directivity of acoustic pressure showed that most of the noise propagates backward direction of the fan-motor assembly. In order to reduce the high tonal sound generated from the aerodynamic interaction, unevenly pitched impeller and diffuser, and tapered impeller designs were proposed and experiments were performed. Uneven pitch design of the impeller changes the sound quality while the overall sound power level (SPL) and the performance remains similar. The effect of the tapered design of impeller was evaluated. The trailing edge of the tapered fan is inclined. This reduces the flow interaction between the rotating impeller and the stationary diffuser because of some phase shifts. The static efficiency of the new impeller design is slightly lower than the previous design. However, the overall SPL is reduced by about 4 dB(A). The SPL of the fundamental blade passing frequency (BPF) is reduced by about 6 dB (A) and the 2$\^$nd/ BPF is reduced about 20 dB (A). The vacuum cleaner with the tapered impeller design produces lower noise level than the previous one, and the strong tonal sound was dramatically reduced.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.52-60
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• 1999

Fabricability of phase shifted grating filters has been theoretically studied by an effective index transfer matrix method. In the optical band-pass filter with multiple ${\lambda}/4$ phase-shifts, the phase-shift error and random variation of the grating period should be suppressed such that corresponding resonance frequency lies within, the filter pass-band. The tolerance for the relative error is less than $10^3$, and is quite stringent in typical filters for WDM application. End facet reflection produces ripple in the transmission spectra and the reflectivity should be less than 1% in order to keep the ripple less than 0.25dB. Also, the effect of waveguide absorption loss is enhanced by the resonance in the filter, and the absorption should be limited to 1dB/cm for the signal loss of less than 0.2dB.