• Sleep Medicine and Psychophysiology
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• v.25 no.2
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• pp.51-57
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• 2018

Objectives: Previous studies have shown that periodic limb movements in sleep (PLMS) could be one of risk factors for cardiovascular morbidity. The purpose of this study was to investigate the association between PLMS and blood pressure changes during sleep. Methods: We analyzed data from 358 adults (176 men and 182 women) aged 18 years and older who were free from sleep apnea syndrome (Respiratory Disturbance Index < 5) and sleep disorders such as REM sleep behavior disorder or narcolepsy. Demographic characteristics, polysomnography records, and clinical variable data including blood pressure, body mass index, alcohol, smoking, and current medications were collected. In addition, self-report questionnaires including the Beck Depression Index, Epworth Sleepiness Scale and Pittsburgh Sleep Quality Index were completed. Blood pressure change from bedtime to awakening was compared between the two periodic limb movement index (PLMI) groups [low PLMI ($PLMI{\leq}15$) and high PLMI (PLMI > 15)]. Blood pressure change patterns were compared using repeated measures analysis of variance. Results: Systolic blood pressure in the high PLMI group was lower than that in the low PLMI group (p = 0.036). These results were also significant when adjusted for gender and age, but were not statistically significant when adjusted for BMI, alcohol, smoking, anti-hypertension medication use and sleep efficiency (p = 0.098). Systolic blood pressure dropped by 9.7 mm Hg in the low PLMI group, and systolic blood pressure in the high PLMI group dropped by 2.9 mm Hg. There was a significant difference in delta systolic blood pressure after sleep between the two groups in women when adjusted for age, BMI, alcohol, smoking, antihypertensive medication use and sleep efficiency (p = 0.023). Conclusion: PLMS was significantly associated with a decreasing pattern in nocturnal BP during sleep, and this association remained significant in women when adjusted for age, BMI, alcohol, smoking, antihypertension medication use and sleep efficiency related to blood pressure. We suggest that PLMS may be associated with cardiovascular morbidity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.7-14
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• 2008

In this paper, we propose VATL(Voltage-controlled Artificial Transmission Line) employing periodically loaded diodes for application to on-chip matching components on MMIC. Compared with conventional microstrip line, the VATL showed a much shorter wave length due to periodic capacitance of diodes, and the characteristic impedance of the VATL was easily controlled bγ changing supplied voltage. Concretely, the characteristic impedance of the VATL was changed from $80{\sim}20{\Omega}$ in a range of $0{\sim}1.05V$ and the VATL showed a wavelength of 1.5mm at 20GHz, while conventional microstrip line showed a wavelength of 5.3mm at the same frequency. Using the VATL, a ${\lambda}/4$ impedance transformer was fabricated on GaAs MMIC for application to on-chip matching components on MMIC. Using the ${\lambda}/4$ impedance transformer made it possible to perform impedance matching between RF components with various characteristic impedance of $30{\sim}100{\Omega}$ by adjusting applied Voltage.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.145-155
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• 2020

The purpose of this study investigates the relationship between business strategy and cost behavior according to the corporate life cycle. To do so, I first examine the relationship between cost behavior and business strategy. And then, I analyze the effect of the business strategy on cost behavior conditional upon corporate life cycle based on listed Korean firms from 2000 to 2019. Specifically, the business strategy index is calculated by using the six continuous financial factors and the Prospector and Defender was defined on the score. Also, the corporate life cycle is distinguished based on the cash flow pattern. I find the evidence that the Prospector firms are likely to strengthen the asymmetry of cost behavior (cost stickiness), and examined that such a relationship was most strongly represented in the Introduction. This study is meaningful in that this is a more comprehensive analysis by examining business strategy and cost strategy according to the corporate life cycle and expand the application of financial information by using financial indicators to distinguish business strategies.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.2
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• pp.117-129
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• 2012

In this study, research was performed to establish the measurement and frequency of analysis for maintenance monitoring by investigation of tunnel maintenance monitoring system in the tunnel which was installed in the Seoul metro line 5, 7 and 8, using that the domestic and foreign application case, results of analyzed maintenance monitoring in the domestic tunnel and legal safety management standard of the facility. The results of the monitoring management about analysis frequency to the present are considered that the problem about measuring frequency does not occur. According to the analysis results of the maintenance monitoring which are located on the 5, 6th subway line, they are analyzed that the stress of concrete lining and reinforced bar are converged gradually after 45 months. Therefore Monitoring of measurement and analysis frequency is conduct more often within about 4 years after the measuring instrument installation. Four years later, slowing the frequency of measurement is considered reasonable.

• Journal of Digital Convergence
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• v.17 no.5
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• pp.11-21
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• 2019

In rapidly changing educational technology and trends, services providing educational digital contents have been focused on offering new contents customized on the state-of-the-art technology and trends, rather than re-evaluating or eliminating the contents on service based on the changed topics and video quality. This study explores domestic cases about educational digital contents in order to draw implications on proper life-cycle models and effective re-evaluation periods for the quality assurance of the contents. To achieve this objective, representative services in primary-secondary, higher, and lifelong education sectors were selected, and experts in the services were participated in focused group interview. Based on the interview results, the re-evaluation process and life-cycle issues in the management of contents were analyzed according to the educational levels and the implications on the life-cycle models were drawn. This study contributes to establishing a basis for the systematic life-cycle policy of the services in order to make more sustainable management of the digital contents.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.661-670
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• 2013

In this paper, we propose the measurement techniques of mixed waveform. Mixed waveform has phase-continuous periodic waveform with fixed frequency signal and Linear Frequency Modulation(LFM) signal. This waveform is generated from a compact radar transmitter with frequency synthesizer and high power amplifier. Frequency synthesizer generates various signal waveform with continuos phase and high power amplifier amplify transmitting signal. First, we describe a compact radar transmitter with the phase-continuos signal and then verify the distortion characteristic of pulse compression by the mismatch of LFM waveform. Second, we describe three kinds of measurement techniques for measuring LFM waveform. These techniques include methods using signal analyzer, signal source analyzer and new methods using RF mixer and phase shifter. Finally, we verify the accuracy of the measurement technique from the pulse compression result of receiving signal.

• Progress in Medical Physics
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• v.13 no.2
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• pp.90-97
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• 2002

The simulator which has a identical geometry with radiotherapy equipments, is a essential equipment to accomplish optimized radiotherapy plan through simulation by using diagnostic low energy X-ray. A Radiotherapy simulator has a combined technology from the therapeutic and diagnostic radiology and needs a periodical test for mechanical and optical properties, X-ray generator, image intensifier of simulator to keep the proper maintenance and radiation safety. Hence, tests were done and classified as i) mechanical and optical parameter for the gantry, collimator, and couch ii) key performance of the X-ray generator such as a kVp, mAs, and timer iii) performance of the image intensifier such as a resolution and contrast for three kinds of simulator, common use in clinic. The above result of tests will be applied to the acceptance test and periodical quality assurance procedure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.199-200
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• 2012

• 전기의세계
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• v.16 no.3
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• pp.34-41
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• 1967

본절에서는 초보적인 Programming을 설명하기 위하여 편의상 몇가지의 구체적인 명령어를 준비래 주기로 한다. 곧 계산기에 따라 명령의 종류 기능이 약간씩 틀리겠지만 현재입수가능한 중형계산기를 염두에 두고 27종의 명령어를 선출하여 이것을 표준 명령으로 쓰겠다.

• 농업기술회보
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• v.47 no.4
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• pp.38-40
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• 2010

파종, 정식, 잡초 뽑기, 물주기, 비료주기, 온도관리, 병해충 방제 수확 등 작물을 파종하고 수확하기까지는 수백 번의 손길과 정성이 필요하다. 정식이 끝난 고추, 오이, 수박 등 주요 과채류의 장마철 농작물 관리요령 등 중점적으로 실천해야 할 재배기술에 대해서 알아보자.