• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.3
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• pp.281-288
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• 2002

This paper has realized a control system of a vibrator using PM excited Transverse Flux Linear Motor(TFLM). Proposed vibrator can supply a vibration force up to 700[N] at rated current, wide operation range of vibration displacement and high frequency for a tested structure. Also, volume of a vibrator system can be decreased because of a high trust force rato(a thrust force per weight=N/Kg). A proposed vibrator instead of a hydraulic vibrator can improve efficiency and have may advantages of maintenance and management. A desired value command is a vibration frequency and displacement in a controller for a vibrator system and a controlled values we a instant position and velocity of a mover Output value of the controller is phase current controlled by PWM converter. In this research, Dynamic simulation has been executed for analysis of a control algorithm and dvnauuc characteristics and is compared with experimental result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.10A
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• pp.1645-1652
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• 2001

제3세대 이동 통신 시스템에서 상향 링크와 하향 링크 사이에 불균형적인 타임 슬롯 할당이 가능한 TD/CDMA TDD 시스템은 비대칭적인 트래픽을 효과적으로 분배하는데 적합하다. 게다가 TD/CDMA TDD 시스템은 슬롯이 시간 영역과 코드 영역에서 정의되기 때문에 유효 자원의 statistical multiplexing이 매우 효과적이다. 그러나 상향 링크와 하향 링크사이의 트래픽의 비대칭성을 반영하기 위해서 타임 슬롯을 최적으로 할당시킬 수 있는 동적 경계선이 요구된다. 본 논문에서 슬롯의 하향 링크부분이 이동국의 접근 시도의 정도에 따라 최대화되는 새로운 최적의 TDD 경계선 제어 움직임 알고리즘을 제안하였다. 제안된 알고리즘에서 이동국의 평균 접근 시도가 미리 정의된 상한 임계치를 초과할 경우, TDD 경계선은 평균 접근 시도가 다른 하한 임계치 아래로 내려갈 때까지 프레임의 중앙에 위치한다. 본 논문에서 모의실험 결과를 통하여 제안된 알고리즘이 기존의 TDD 경계선 알고리즘보다 데이터 트래픽의 평균 접근 지연과 음성 트래픽의 블록킹 확률 측면에서 훨씬 더 좋은 성능을 나타냄을 입증하였다.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.165-172
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• 2015

The class of Dynamic Positioning System is divided in 3 classes depending on its redundancy and reliability according to IMO and classification society. There are 3 DP classes such as DP Class 1, 2 and 3 according to IMO MSC/Circ. 645. Higher DP class vessel has higher reliability, since redundancy concept is applied to the DP vessel depending on its DP class and can operate more safely. There are not enough information about DP class notation, which are needed when a company builds a new or buys second hand DP vessel or modifies DP classes, even the Korean shipyard is building a lot of DP vessels now. Also, the practical case of DP vessel modification, which had been done in Korea, to meet DP notation of IMO and classification society, will be helpful for DP vessel modification and sales industry development in Korea as a new business. As such this research identified what kind of requirements need to be taken into account to be from DP class 1 to DP class 2. The real DP class modification case is used to identify the requirements of DP class upgrade. Through the FMEA the redundancy concept on power system, thruster system and DP control system need to apply for DP class upgrade. The power system have to keep its DP function even if just a single fault happens on the generator or switchboard. Also, the PMS is required to monitor and control power system. Ship's Surge, Sway and Yaw movements can be controlled by the remaining thruster system after a single thruster fails. Lastly, multiple installation of PRS, sensors and DP control system are required to keep DP ability after a single fault on the DP control systems.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.415-426
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• 2006

The essential characteristic of ubiquitous is context-awareness, and that means ubiquitous computing can automatically process the data that change according to space and time, without users' intervention. However, in circumstance of context awareness, since location information is able to be collected without users' clear approval, users cannot control their location information completely. These problems can cause privacy issue when users access their location information. Therefore, it is important to construct the location information system, which decides to release the information considering privacy under the condition such as location, users' situation, and people who demand information. Therefore, in order to intercept an outflow information and provide securely location-based information, this paper suggests a new system based CS-RBAC with the existing LBS, which responds sensitively as customer's situation. Moreover, it accommodates a merit of PCP reflecting user's preference constructively. Also, through privacy weight, it makes information not only decide to providing information, but endow 'grade'. By this method, users' data can be protected safely with foundation of 'Role' in context-aware circumstance.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.1
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• pp.63-70
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• 2008

As the number of cell phone users become growing, some researchers have presented that the imprudent use of mobile phones exerts harmful influence on electronic devices such as medical appliances, takeoff and landing system of aircraft. In this paper, we propose a usage model based on context-awareness which can be applied to mobile devices. The model controls the usage of both mobile devices themselves and mobile contents according to some context information like location, time, the circumference noise, etc. The proposed usage control model includes a dynamic role-based access control approach. To show the effectiveness of the proposed model, we have implemented a prototype system on an embedded board and PC server, and evaluated the performance of the system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.330-340
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• 2009

A naval shipboard inevitably movies in a pitch and roll direction under the influence of wave and wind in the sea. As a result, the shipboard gets in a continuous turning motion back/front and right/left. And the shipboard is also constantly exposed to many different kinds of disturbance signals including the vibrations of various frequencies from the internal equipments and their vibrations, strong waves, and impact from explosion. This paper formulates multi-body dynamic models similar to an actual system and simulates the pitch/roll positions of a 2-axes gimbals with PI controller for consecutive behavior of a naval shipboard including disturbance.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.407-417
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• 2005

An experimental and analytical study was performed to apply the friction pendulum system (FPS) to the main control room of a nuclear power plant. A friction pendulum bearing was fabricated, and the dynamic response of the bearing was evaluated. A partial model of a main control room attached to the FPS was tested on the shake table. The model consisted of a cabinet, a $3m\times3m$ access floor, and four friction pendulum bearings. The artificial time history based on the floor response spectrum of the main control room was used as the earthquake input signal in the test. Comparisons between the analytical study and the experimental study were conducted to verify the results and to extend the experimental study to the range of parameters that could not be experimentally studied.

• The KIPS Transactions:PartD
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• v.12D no.6 s.102
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• pp.905-914
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• 2005

This paper suggests a healthcare home service system based on the distributed object group framework that can not only provide healthcare application services using the information obtained from the physical healthcare sensors and devices, and but also monitor and control these services remotely. The distributed object group framework supports the object group service, the interaction service between object groups and the real-time service in order to execute the healthcare application. Here object group means the unit of logical grouped objects or healthcare sensors and devices for a service. Our suggested system consists of 3 layers. The first layer presents the physical sensors and devices for healthcare, as a physical layer. The second layer lays the distributed object group framework, and the third layer, the upper's one, implements healthcare applications based on lower layers. With healthcare applications providing for this system, we implemented the location tracking service, the health information service and the titrating environment service. Also the integrated executing results of these services can be monitored and controlled via remote desktop systems or PDAs.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.919-925
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• 2023

Modern drones are equipped with miniaturized mission equipment capable of performing various tasks such as surveillance and reconnaissance. Consequently, these mission equipment are exposed to disturbances like wind loads and motor rotations, which can lead to instability in the operation of the Electro-Optical Targeting System (EOTS). Specifically, simple step inputs for changing the line of sight in EOTS can cause abrupt changes in speed, inducing overshoot and potentially creating instability along with other disturbances. To address this, a velocity profile was designed so that the angular velocity moves in a trapezoidal shape when changing the EOTS line of sight. A Double-loop controller was designed to apply this profile as an input to the external loop receiving position feedback. The system's stability was then compared, and the velocity profile was optimized within a stable range by varying maximum speed and acceleration.

• Journal of the Institute of Convergence Signal Processing
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• v.23 no.4
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• pp.185-193
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• 2022

This paper proposes an adaptive sliding mode control with radial basis function neural network(RBFNN) scheme to enhance the performance of position and attitude tracking control of quadrotor UAV. The RBFNN is utilized on the approximation of nonlinear function in the UAV dynmic model and the weights of the RBFNN are adjusted online according to adaptive law from the Lyapunov stability analysis to ensure the state hitting the sliding surface and sliding along it. In order to compensate the network approximation error and eliminate the existing chattering problems, the sliding mode control term is adjusted by adaptive laws, which can enhance the robust performance of the system. The simulation results of the proposed control method confirm the effectiveness of the proposed controller which applied for a nonlinear quadrotor UAV is presented. Form the results, it's shown that the developed control system is achieved satisfactory control performance and robustness.