• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.426-429
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• 1989

The robust self-tuning controller is designed which is guaranteed the asymptotic regulation and tracking in the presence of a bounded parameter perturbation. The global stability in the presence of a finite noise and disturbance is ensured. The controller has a error driven structure, and involves the common model of a disturbance and reference input in the internal model. The adaptive system tunes the controller parameters such that the quadratic performance index which involves a weighting factor is optimized.

• 전기학회논문지
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• 제58권1호
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• pp.160-167
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• 2009

In this paper, we apply the robust disturbance observer (DOB) to a SPM-based data storage (SDS) system. In the SDS system, coupling dynamics and parameter uncertainties are obstacles to the precision tracking control. Although the DOB is known to be an effective method to reject disturbances, there has been no systematic design approach to how to design DOB parameters. In this paper, the robust DOB is formulated based on the robust stabilization of normalized coprime factor plant description and the $H{\infty}$ loop shaping method. From the simulation and experimental results. the improved robustness and performance are obtained by the proposed robust DOB.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.190-190
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• 2000

This paper presents a multirate state feedback control (MRSFC) method for systems sensitive to disturbance and noise based on the multirate estimator design using the current estimator. MRSFC updates the controller output slower than the measurement sampling frequency of system output by a lifting factor R=T$\sub$c//T$\sub$s/. The closed-loop MRSFC system is less sensitive to disturbance and noise due to filtering effect than the conventional single-rate control system. The multirate estimator gain is obtained from solving a conventional pole placement problem such that MRSFC has the same spectrum of eigenvalues in the s-plane as the single-rate control. We applied the proposed multirate state feedback controller to a galvanometer servo system. Simulation and experimental results show that settling and tracking performances are improved compared with a conventional single-rate pole placement control (PPC).

• 한국초전도ㆍ저온공학회논문지
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• 제1권2호
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• pp.37-42
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• 1999

The stability of high-temperature superconducting current leads for cryogenic devices are investigated. By assuming full transition from superconducting state to normal state at a transition temperature, the HTS current at a transition temperature, the HTS current lead shows bifurcation phenomenon. There is a bifurcation shape-factor, HTS leads have three steady state. Below the bifurcation shape-factor, the superconducting current lead is unconditionally stable, because there exists only one steady-factor HTS current lead is conditionally stable depending on the shape and intensity of disturbance.

• 터널과지하공간
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• 제20권3호
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• pp.225-232
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• 2010

본 연구에서는 절리에 작용하는 수직변형과 전단 팽창을 고려할 수 있는 수정된 3차원 변형률 의존성 수리전도도 변화 방정식을 제안하였다. 현지 암반을 직교절리가 발달한 매질로 가정하기 때문에 제시된 방정식을 사용하여 수리전도도의 이방성을 평가할 수 있다. 현지암반의 변형계수를 필요로 하는 탄성계수감소비를 손쉽게 결정하기 위하여 GSI와 교란계수를 기초로 하는 경험식을 사용하였다. 현지 암반 내에 존재하는 절리는 일반적으로 전체좌표계와 평행하지 않고 기울어져 있는 경우가 많기 때문에 기울어진 방향에서의 수리전도도를 구하기 위하여 변형률 회전식을 사용하였다. 해석 결과 GSI가 증가함에 따라 수리전도도는 감소하는 것으로 나타났다. 교란계수는 수리전도도의 변화 거동에 영향을 미치는 것으로 나타났는데 특히 GSI가 50 이상인 암반의 수리전도도 변화에 큰 영향을 미치는 것으로 해석되었다. 절리의 경사도 수리전도도 변화에 영향을 미치는 것으로 나타났다.

• 대한간호학회지
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• 제40권1호
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• pp.43-51
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• 2010

Purpose: The purpose of this study was to investigate sleep habits, sleep disturbance, and circadian types, and to identify factors influencing sleep disturbance in nursing students. Methods: Participants were 140 senior nursing students. The data were collected from May 19 to 27, 2008 using self-report questionnaires. Results: 1) Evening type delayed sleep-wake schedules were more frequent than for morning type, especially during weekend and evening shift duty. 2) In total sleep time, there were no significant statistical differences between morning type and evening type during weekdays, weekend, day or evening shift duty. 3) On weekdays and day shift duty, the mean score for sleep disturbance was significantly higher in the evening type compared to the morning type. 4) Sleep disturbance in weekday and day shift duty was influenced by circadian types, eating habits, and gender. Conclusion: The circadian types are a very important factor for determining the sleep quantity and quality in nursing students.

• Journal of Oral Medicine and Pain
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• 제26권4호
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• pp.369-376
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• 2001

Objectives : The purposes of the study was to evaluate cephalometric characteristics in snorers and patients with obstructive sleep apnea (OSA) and to see any relationships between the cephalometric measurements and respiratory disturbance indices (RDI). Materials and Methods : Twelve snoring patients, 11 patients with OSA, and 10 normal subjects were included for the study. After taking a screening sleep study for a night to obtain RDI, $SaO_2$, and snoring index, a detailed cephalometric analysis was conducted to obtain SNA, SNB, SN-MP, IAS, MAS, SPAS, SAAS, Mn-H, and PNS-P. All the data were compared between groups. For a group including 12 snoring patients and 11 OSA patients, correlation coefficients were calculated between respiratory disturbance index and each item of cephalometric measurements. Results : The mandible and the maxilla are retropositioned. The oropharyngeal and hypopharyngeal airway is reduced in area and is a factor that could produce or enhance OSA symptoms. The hyoid bone is displaced inferiorly. The soft palate is significantly elongated. Conclusions : These data suggest that cephalometric evaluation could be useful to evaluate snoring and OSA patients, and to assist with the planning treatment for improvement of upper airway patency.

• Journal of Oral Medicine and Pain
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• 제43권1호
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• pp.8-15
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• 2018

Purpose: The purpose of this study was to assess the association of vocational interest and personality with oral mucosal diseases. Methods: Three hundred and fifty eight college students in Gyeonggi-do completed Vocational Preference Inventory L form and a questionnaire and collected data were analyzed by R program. Results: The prevalence of symptoms of oral mucosal diseases showed no significant difference among six vocational personality types. Compared to subjects with good or fair general health status, a significantly increased percentage of subjects with bad general health status showed herpetic stomatitis (p<0.01), oral malodor (p<0.01), and glossodynia (p<0.0001). Prevalence of taste disturbance increased significantly as the score of emotional instability (${\beta}=0.0438$, p=0.0082), anxiety (${\beta}=0.038$, p=0.0174), angry hostility (${\beta}=0.0398$, p=0.0061), depression (${\beta}=0.0443$, p=0.0035), and impulsiveness (${\beta}=0.0358$, p=0.0186) increased. Subjects who strongly felt oral malodor revealed significantly higher mean scales of scores of anxiety and angry hostility than subjects who did not feel oral malodor (p<0.05). Subjects who strongly felt oral malodor manifested significantly higher mean scales of scores of anxiety than subjects who slightly felt oral malodor (p<0.05). Conclusions: Taste disturbance was affected by emotional instability, anxiety, angry hostility, depression, and impulsiveness. Oral malodor was related to anxiety and angry hostility. Therefore, psychological aspects of taste disturbance and oral malodor could be evaluated by Vocational Preference Inventory L form.

• Safety and Health at Work
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• 제13권1호
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• pp.3-8
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• 2022

Background: This study aims to allow the development of efficient measures to improve occupational health of shift-working nurses focusing on job stress, health promotion behavior, resilience, and sleep disturbance. Methods: It was conducted on a subject panel of 137 nurses who were aware of the purpose of the study and agreed to participate. They worked three shifts at a tertiary hospital or a general hospital located in metropolitan city B. The collected data were analyzed by the independent t test and one-way analysis of variance and post-tested by Scheffe's test, Pearson's correlation coefficients, and multiple linear regression analysis using SPSS/WIN 25.0. Results: The significant influencing factors on sleep disturbance were of those whose subjective health status was 'normal' (b = 0.29, p < .001), 'not healthy' (β = .40, p < .001), who have job stress (β = .22, p = .003), and who have health promotion behavior (β = -0.17, p = .023). The overall explanatory power was 31.1% (F = 16.31, p < .001). Conclusion: Through this study, nurses' subjective health status and job stress of working shifts were found to be important factors influencing the sleep disturbance level, and the most influencing factor was identified as the subjective health status.

• 수산해양기술연구
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• 제59권2호
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• pp.145-154
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• 2023

In this study, to control the heading angle of a ship, which is constantly subjected to various internal and external disturbances during the voyage, an LADRC (linear active disturbance rejection control) design that focuses more on improving the disturbance removal performance was proposed. The speed rate of change of the ship's heading angle due to the turn of the rudder angle was selected as a significant factor, and the nonlinear model of the ship's maneuvering equation, including the steering gear, was treated as a total disturbance. It is the similar process with an LADRC design for the first-order transfer function model. At this time, the gains of the controller included in LADRC and the gains of the extended state observer were tuned to RCGAs (real-coded genetic algorithms) to minimize the integral time-weighted absolute error as an evaluation function. The simulation was performed by applying the proposed GA-LADRC controller to the heading angle control of the Mariner class vessel. In particular, it was confirmed that the proposed controller satisfactorily maintains and follows the set course even when the disturbances such as nonlinearity, modelling error, uncertainty and noise of the measurement sensor are considered.