• Journal of Preventive Medicine and Public Health
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• 제28권4호
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• pp.773-782
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• 1995

The purpose of this study is to reveal how the road traffic noise influences on the response of teachers and students, which composed of conversation, studying, relaxation, and physical disturbances. The research method used in this study was self-administrated questionnaire. Samples of the survey were composed of 420 persons(114 teachers and 306 students) who are exposed to traffic noise less than 65 dB(A) from two junior high schools and 410 persons(140 teachers and 270 students) from two noisy junior high schools which the road traffic noise above 65 dB(A). In the response of both of the teachers and students in noisy(above 65 dB) schools complaints of disturbances of conversation, studying, relaxation, and physical disturbances are much higher than that of less noisy schools' teachers and students(p<0.01). On the occasion of time and season, the subjects answered the traffic noise cause high troublesome and stresses in the afternoon(12:00 - 17:00) and summer respectively. It is necessary to provide governmental comprehensive and fundamental measures to improve the noisy school environments.

• 한국산업정보학회논문지
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• 제7권4호
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• pp.66-73
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• 2002

일반적으로 가변구조제어는 외란과 변수 변화에 대해 강인한 특성을 가지지만 제어기 설계자는 이러한 값들에 대한 상한 값과 하한 값을 알아야한다. 그러나 때로는 이러한 상한 값과 하한 값을 얻는다는 것은 쉽지가 않다. 이에 반해 퍼지제어기는 외란과 변수 변화에 대한 제어기 설계에 있어서 효과적인 방법을 제공한다. 따라서 퍼지제어기와 가변구조제어기가 가지는 장점들을 결합하는 연구가 진행되어져 왔다. 본 논문에서는 리칭페이저가 존재하는 기존의 슬라이딩모드제어기를 이용하는 방법 대신 리칭페이저를 제거하여 전 구간 강인한 적응 퍼지가변구조제어기를 설계하였다. 제안된 제어 알고리듬은 BLDC 전동기의 위치제어기로 사용하였으며, 그 타당성을 입증하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권1호
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• pp.98-118
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• 2014

An auto weather-vaning system for a Dynamic Positioning (DP) vessel is proposed. When a DP vessel is operating, its position keeping is hindered by ocean environmental disturbances which include the ocean current, wave and wind. Generally, most ocean vessels have a longitudinal length that is larger than the transverse width. The largest load acts on the DP vessel by ocean disturbances, when the disturbances are incoming in the transverse direction. Weather-vaning is the concept of making the heading angle of the DP vessel head toward (or sway from) the disturbance direction. This enables the DP vessel to not only perform marine operations stably and safely, but also to maintain its position with minimum control forces (surge & sway components). To implement auto weather-vaning, a nonlinear controller and a disturbance observer are used. The disturbance observer transforms a real plant to the nominal model without disturbance to enhance the control performance. And the nonlinear controller deals with the kinematic nonlinearity. The auto weather-vaning system is completed by adding a weather-vaning algorithm to disturbance based controller. Numerical simulations of a semi-submersible type vessel were performed for the validation. The results show that the proposed method enables a DP vessel to maintain its position with minimum control force.

• 한국항공우주학회지
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• 제49권10호
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• pp.821-828
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• 2021

쿼드로터는 다른 비행체에 비해 작고 가벼워서 바람과 같은 외란에 민감하다는 단점이 있다. 이 단점을 해결하기 위해 외란에 강인한 제어기법을 이용하는 연구가 많이 이루어져 왔다. 본 논문에서는 외란을 해결하기 위해 적은 힘으로 큰 토크를 발생시킬 수 있는 CMGs (Control Moment Gyros)를 활용하였다. 쿼드로터의 자세 제어를 위해 2개의 CMGs를 활용하였고, 4개의 로터와 2개의 CMGs를 구동하기 위한 시스템을 구성하였다. 구성한 시스템의 제어 성능을 확인하기 위해 외란이 있는 환경에서 자세 제어에 대한 시뮬레이션을 진행하였다.

• 해양환경안전학회지
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• 제25권3호
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• pp.306-312
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• 2019

This paper investigates to design a controller for maritime autonomous surface ship (MASS) by means of adaptive super-twisting algorithm (ASTA). A input-out feedback linearization method is considered for multi-input multi-output (MIMO) system. Sliding Mode Controller (SMC) is suitable for MASS subject to ocean environments due to its robustness against parameter uncertainties and disturbances. However, conventional SMC has inherent disadvantages so-called, chattering phenomenon, which resulted from the high frequency of switching terms. Chattering may cause harmful failure of actuators such as propeller and rudder of ships. The main contribution of this work is to address an appropriate controller for MASS, simultaneously controls surge and yaw motion in severe step inputs. Proposed control mechanism well provides convergence bewildered by external disturbances in the middle of steady-state responses as well as chattering attenuation. Also, the adaptive algorithm is contributed to reducing non-overestimated value of control gains. Control inputs of surge and yaw motion are displayed by smoother curves without excessive control activities of actuators. Finally, no overshoot can be seen in transient responses.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1644-1651
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• 2022

This paper focuses on the power-level control of nuclear power plants (NPPs) in the presence of lumped disturbances. An adaptive second-order nonsingular terminal sliding mode control (ASONTSMC) scheme is proposed by resorting to the second-order nonsingular terminal sliding mode. The pre-existing mathematical model of the nuclear reactor system is firstly described based on point-reactor kinetics equations with six delayed neutron groups. Then, a second-order sliding mode control approach is proposed by integrating a proportional-derivative sliding mode (PDSM) manifold with a nonsingular terminal sliding mode (NTSM) manifold. An adaptive mechanism is designed to estimate the unknown upper bound of a lumped uncertain term that is composed of lumped disturbances and system states real-timely. The estimated values are then added to the controller, resulting in the control system capable of compensating the adverse effects of the lumped disturbances efficiently. Since the sign function is contained in the first time derivative of the real control law, the continuous input signal is obtained after integration so that the chattering effects of the conventional sliding mode control are suppressed. The robust stability of the overall control system is demonstrated through Lyapunov stability theory. Finally, the proposed control scheme is validated through simulations and comparisons with a proportional-integral-derivative (PID) controller, a super twisting sliding mode controller (STSMC), and a disturbance observer-based adaptive sliding mode controller (DO-ASMC).

• 로봇학회논문지
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• 제17권3호
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• pp.339-346
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• 2022

To operate in real environment, humanoid robots should be able to react to unknown disturbances. To deal with disturbances, various robust control algorithms have been developed for decades. But for collaborative works such as teleoperation system, a compliance control can be the better solution for disturbance reactions. In this paper, a center of mass (CoM) compliance control algorithm for humanoid robots is proposed. The proposed algorithm is based on the state observer and positive feedback of disturbance. With the state observer based on humanoid CoM control performance model, disturbance in each direction can be observed. The positive feedback of disturbances to the reference CoM trajectory enables compliant motion. The main contributions of this algorithm are achieving compliance independently in each axis and maintaining balance against external force. Through dynamic simulations, the performance of the proposed method was demonstrated. Under two types of disturbance conditions, humanoid robot DYROS-JET reacted with compliant motion via the proposed algorithm.

• 한국정보전자통신기술학회논문지
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• 제16권6호
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• pp.472-477
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• 2023

본 논문에서는 쿼드콥터 드론이 동적인 외부 환경 아래서도 외란에서도 효과적으로 경로를 추종하고 비행 안전성을 유지할 수 있도록 모델 예측 제어(MPC) 기법을 제안한다. MATLAB/Simulink에서 수행된 시뮬레이션을 통해, 외란이 주어지는 비행 시나리오에서 PID와 MPC 두 제어기의 성능을 비교한다. 제안된 설계 방법으로 MPC 제어기가 압력 변화와 공기 밀도 변동과 같은 외란에 대하여 MPC와 PID 제어기의 성능을 비교했을 때에 쿼드콥터 드론의 입력받은 주행 경로와 실제 경로의 Mean Squared Error 수치가 외란을 주기 전에는 0.2의 성능 차이를 보였다. 그리고, 외란을 주었을 때에는 0.8을 차이를 보이며 MPC 제어기의 향상된 경로 추종 정확도를 보여준다.

• Current Optics and Photonics
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• 제8권2호
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• pp.138-150
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• 2024

This study is essential for advancing our knowledge about the interaction between long-range high-power lasers and energetic materials, with a particular emphasis on understanding the response of a 155-mm shell under various surface irradiations, taking into account external factors such as atmospheric disturbances. The analysis addresses known limitations in understanding the use of non-realistic targets and the negligence of ambient conditions. The model employs the three-dimensional level-set method, computer-aided design (CAD)-based target design, and a message-passing interface (MPI) parallelization scheme that enables rapid calculations of the complex chemical reactions of the irradiated high explosives. Important outcomes from interaction modeling include the accurate prediction of the initiation time of ignition, transient pressure, and temperature responses with the location of the initial hot spot within the shell, and the relative magnitude of noise with and without the presence of physical ambient disturbances. The initiation time of combustion was increased by approximately a factor of two with atmospheric disturbance considered, while slower heating of the target resulted in an average temperature rise of approximately 650 K and average pressure increase of approximately 1 GPa compared to the no ambient disturbance condition. The results provide an understanding of the interaction between the high-power laser and energetic target at a long distance in an atmospheric condition.

• Journal of Oral Medicine and Pain
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• 제38권4호
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• pp.313-318
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• 2013

수면은 외부의 자극에 대해 반응하지 않는 상태로 만성통증을 지닌 환자는 수면 장애를 겪고 있으며 수면장애는 통각과 민한 상태를 유발하고 통증인지에 영향을 미친다. 구강작열감 증후군은 구강점막에 화끈거리는 감각을 포함하는 만성 안면통증으로 감각과 통증 역치가 변성되고 신경병증 징후를 보인다. 구강작열감 증후군은 첫 번째로 국소적, 전신적 요인 즉, 흡연, 투약 등 작열감 증상의 원인으로 가능한 요인을 제거하고, 두 번째로는 환자를 안심시키는데 있다. 수면박탈 내인성, 외인성 아편유사제의 진통효과는 수면 계속성 즉, 선택적인 렘수면 박탈은 아편유사제 진통효과를 방해 하고 opioid protein synthesis 억제를 야기하고 ${\mu}$ 와 ${\delta}$ opioid 수용체 친화력을 감소시킨다. enkephalinase-inhibitor와 MAO-B inhibitor 적용으로 나타나는 아편유사제의 진통상승효과는 렘수면 박탈시에 무효화 된다. 렘수면 박탈후에는 5-HT 와 5-hydroxy indole acetic acid 레벨이 유의하게 감소되고, 아편유사체에 활성에 의해 유발되는 통증억제를 지지하는 세로토닌 체계를 가능하지 않게 한다. 구강작열감 증후군은 설말단 신경섬유에서 추삭변성 변화가 있고 특히, 열자극, 냉자극 및 미각 유해수용성 자극의 인지를 포함한 감각변화가 폐경기후 생식스테로이드의 급격한 감소가 신경활성 스테로이드 생성에 변성을 일으켜며, 이것은 말초성 변성와 중추성 변성이 존재함을 제시한다. 구강작열감 증후군은 기본적으로 가능한 요인을 제거하는 것이 중요하므로 구강작열감의 진행을 방지하고, 만정적인 작열감의 경감을 위하여 증상 경과에 영향을 미칠 수 있는 수면에 대하여 고찰하고자 한다.