• 전기학회논문지
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• 제58권7호
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• pp.1405-1410
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• 2009

Output voltage of a DC/DC power converter system is likely to be distorted if variable loads exist in the output terminal. This paper presents a new disturbance observer(DOB) approach to maintain a robust regulation of the output voltage of a boost type DC/DC converter. Unlike the buck-type converter case, the regulation problem of the boost converter is very complicated by the fact that, with respect to the output voltage to be regulated, the system is non-minimum phase. Owing to the non-minimum phase property the classical DOB approach has not been applied to the boost converter. Motivated by a recent result on the application of DOB to non-mimimum phase system, an output feedback control law is proposed by using a parallel feedforward compensator. Simulation results using the Simulink SimPowerSystems prove the performance of the proposed controller against load variation.

• 대한한의학회지
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• 제17권1호
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• pp.247-265
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• 1996

To study the clinical effect of moxibustion on the urinary disturbance, which is one of the most common complications of CVA, 60 patients with urinary disturbance due to CVA, who had been hospitalized in Hespital of Oriental Medicine, KyungHee University Medical Cental from May 1st, 1995, to September 20th, 1995, had been selected, and moxibustion treatment had been done. The results were as follows ; 1. In the relation between the radiological size of the lesion and recovery, the real moxibustion group showed significant recovery compared to sham moxibustion group and non moxibustion group in the middle size lesion patients. 2. In the relation between the anatomical lesion and recovery, there was no significant difference among real moxibustion group, sham moxibustion group and non moxibustion group. 3. In the relation between the initial state of urinary disturbance and recovery, the real moxibustion group showed significant recovery compared to sham moxibustion group and non moxibustion group in Gr 3 patients. 4. In the relation between the type of urinary disturbance and recovery, there was no significant difference among real moxibustion group, sham moxibustion group and non moxibustion group.

• 중환자간호학회지
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• 제13권3호
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• pp.1-10
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• 2020

Purpose : This study aims to investigate the differences in fatigue, sleepiness, and near-miss according to sleep disturbance among shift nurses in intensive care units (ICUs). Methods : A cross-sectional study in a tertiary hospital was performed. A total of 122 shift nurses working in the six ICUs were recruited. They completed self-reported questionnaires about sleep disturbance, fatigue, sleepiness, and near-miss in the past two weeks. Results : The prevalence of reported sleep disturbance was 30.3% (37 out of 122 subjects). Compared to the non-sleep disturbance group, the sleep disturbance group reported significantly more sleepiness (11.46 vs. 8.86) and higher fatigue (82.62 vs. 69.39). The sleep disturbance group showed higher rates of near-miss (78.4 vs. 57.6%) and a higher frequency of them (4.49 vs. 2.11/2weeks) compared to the non-sleep disturbance group. Medication error was the most common type of near-miss. Conclusions : This study suggests that sleep disturbances could increase fatigue, sleepiness, and near-miss among ICU shift nurses. Personal and organizational programs should be developed to support the sleep of ICU nurses.

• The Korean Journal of Ecology
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• 제26권5호
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• pp.255-261
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• 2003

To analyze ecological characteristics of the Ulmus pumila community, an on-the-spot survey was conducted in August, 1998 in the Dong River, Gangwon-do, South Korea. The Ulmus pumila community is partially distributed in Dong River's midstream and upper stream. Topographical characteristics of this community are significant in the point bar or sandbank of the river. The community is classified into two types, disturbed and non-disturbed types, by the effect of flooding. The Ulmus pumila community (bush forests of Siberian elms) is a representative community which forms riparian forests, but its distribution is rare in South Korea. Only in Dong River is the Ulmus pumila distributed enough to form a community, and none is known that is lager than this community in South Korea. The non-disturbance type progresses more homogeneously than the disturbance type because it is formed on riverside banks where it is affected less by flooding. We concluded that the Ulmus pumila community in this study area has characteristics of riparian forests. In South Korea, Ulmus pumila community can be regarded as important element of vegetation landscape constituting riparian forests. Specifically, these riparian forests are evaluated as high in conservation value due to their being formed spontaneously. Moreover, Dong River is regarded as the southern limit of Ulmus pumila, which has a northern origin. The species or community needs continuous interests and conservation countermeasures because there are limitations in its spread of distribution by natural or artificial efforts.

• The Korean Journal of Ecology
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• 제18권1호
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• pp.179-188
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• 1995

Death patterns of gap-makers and changes of environmental factors in gaps formed by disturbance were studied in Pinus densiflora forests of Youngwol, Mt, Mansu, Mt. Songni, Uljin, and Mt, Obong in Korea. Death pattern of gap-makers showed that standing deat type was the most frequent in all the study areas. Longevity of Pinus densiflora was about 140 years, which was about half of that of the temperate deciduous broad-leaved trees. size of gaps were distributed from $20m^2$ to $235m^2$, more than 80% of those were gaps created by death of two or more trees. Relative light intensity and water content of soil in gap area were higher than those in non-gap area and those in the central part of gap were the highest.

• 한국항행학회논문지
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• 제3권2호
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• pp.97-107
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• 1999

항공기의 착륙을 추적하기 위해 많이 사용되는 수동 센서인 레이저 거리 측정기(LRF)와 전방관측 적외선 카메라(FLIR)는 배기가스교란(Exhaust Plume Disturbance)으로 인한 고도각 측정 시에 오차를 발생시킨다. 이 경우에 확장형 칼만필터(EKF)를 사용하여 거리 및 고도를 측정하면 배기가스(plume)와 같은 비-가우시안 잡음 때문에 추적 성능이 저하된다. 본 논문에서는 배기가스의 발생 타이밍을 검출기(PD)를 사용하여 확인한 후에 배기가스가 발생하면 적응형 추산법을 사용하고 배기가스의 영향이 없을 때에는 기존의 확장형 칼만필터를 사용하는 복합 방식을 제안하고 이를 위한 적응형 필터를 설계한다. 이 혼합형 필터는 배기가스와 같은 미지의 바이어스를 제거하는데 매우 효과적인 방법이며 시뮬레이션을 통하여 이러한 성능을 예증한다.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.944-949
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• 2017

Recently, the demand of maglev systems in the manufacturing industry for LCD and OLED display panels, which are required to be very clean and possess vacuum systems, has been increasing due to their characteristics such as being non-contact, noise free and eco-friendly. However, it is still a challenge to simultaneously control both the propulsion and levitation for their interactive effect difficult to be exactly measured. In this paper, we proposed a new tuning method for controlling the magnetic levitation force robustly against the levitation disturbance caused by a propulsion system, based on LQ servo optimal control. The disturbance torque of the LSM propulsion system is calculated through FEM analysis in such a way that the LQ servo controller is determined in order to minimize the effect of the disturbance. The robust performance of the proposed LQ servo control method for the in-track type magnetic levitation systems is demonstrated via simulations and experiments.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제37권6호
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• pp.448-456
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• 2011

Introduction: Condylar fractures are common in the maxillofacial region, comprising 29-40 percent of all mandibular fractures, accounting for about 20-62 percent). Previous studies reported that pediatric condylar fractures can cause disorders in facial growth and function, and the treatment methods have been controversial. Recently, conservative treatment has shown good results in skeletal growth and functional recovery but the conservative treatment of pediatric condylar fractures has shown unpredictable and undesirable results in some cases, such as facial asymmetry and temporomandibular joint disorder. This study examined the specific age groups and specific mandibular condylar fracture type in growing children treated conservatively in the past. Materials and Methods: Eighteen patients (10 men and 8 women) who received conservative treatment for unilateral condylar fractures in Dankook University Dental Hospital between 2000 to 2007 were followed up for a mean period of 7.2 years. Results: In the survey of 18 pediatric patients who received conservative treatment for condylar fractures, the incidence of temporomandibular dysfunction and growth disturbance was 45% and 35%, respectively. Conclusion: In all complications, the symptoms observed most frequently was mouth opening displacement of the mandible exceeding 2 mm. The other complications of functional and growth disturbance included facial asymmetry concentrated along specific condylar types. Complications including facial asymmetry and functional and growth disturbances showed an increasing tendency according to the specific fracture types. Functional and growth disturbances in the undisplaced condylar fracture type showed a lower incidence(P <0.05). Functional and growth disturbances differed according to the fracture type, which has poor relationship with articular fossa and condyle(P <0.05). Functional and growth disturbance in the cases of the high-level condylar fracture type showed a higher incidence(P <0.05). The functional and growth disturbances of the fracture types were similar in the fragment-contact and non-contact groups(P >0.05).

• International Journal of Aeronautical and Space Sciences
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• 제17권2호
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• pp.195-203
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• 2016

In order to overcome the influence of system stability and accuracy caused by uncertainty, estimation errors and external disturbances in Eight-Rotor MAV, L2 gain control method was proposed based on interval type II fuzzy neural network identification here. In this control strategy, interval type II fuzzy neural network is used to estimate the uncertainty and non-linearity factor of the dynamic system, the adaptive variable structure controller is applied to compensate the estimation errors of interval type II fuzzy neural network, and at last, L2 gain control method is employed to suppress the effect produced by external disturbance on system, which is expected to possess robustness for the uncertainty and non-linearity. Finally, the validity of the L2 gain control method based on interval type II fuzzy neural network identifier applied to the Eight-Rotor MAV attitude system has been verified by three prototy experiments.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.1004-1011
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• 1996

This paper covers the technology developmental stage work for the automatic ammunition loading system mainly focusing on the controller design of the electro-hydranlic type direct drive multi-axis manipulator. Mathematical model of the plant derived and PIDM servo-controller structured. Comparative study between the analytical and experimental work has been carried out to help understand the response property of the direct dine multi-axis robot. In the direct drive robot, non-negligible amount of disturbance and load Induced dynamics variation are transmitted to the drive axis and nonlinearity is highly observed. Thereupon a robust controller Implementing time-delay control law is proposed, and computer simulation confirms the possibility for the time-delay control application against the unpredictable disturbance and load-Induced dynamics variation.