• 농업과학연구
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• 제47권4호
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• pp.1147-1158
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• 2020

The purpose of this study was to measure the engine torque and rotational speed of a 67 kW class agricultural tractor according to tire type during plow tillage and to analyze the gear strength of the driving shift for the tractor. A field test was performed under the condition with a single tire (Test A) and dual tires (Test B) to increase the ground width of the rear tires. A load monitoring system was developed, and the engine torque and rotational speed were measured using controller area network (CAN) communication. The engine torque and rotational speed during plow tillage were calculated as the equivalent torque and speed using Palmgren Miner's rule. As a result, the equivalent torque and speed in Test A and Test B were 181.0 Nm and 1,913 rpm and 206.1 Nm and 2,130 rpm, respectively. As the ground width of the rear tire was increased, the bending stress in Test B was about 9.9 to 10.5% higher than that of the Test A, and the contact stress was about 4.6 to 4.9% higher than that of the Test A. Under all conditions, the safety factor for the bending and contact stress was 1 or more. Thus, the driving shift gears for the dual tire type are considered safe.

• 한국안전학회지
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• 제28권2호
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• pp.21-25
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• 2013

The purpose of this study is to provide basic data for the safety assessment of a water purifier when water leaks due to inappropriate maintenance and the examination of the cause of accidents related to the leak. Due to its inspection and management by non-specialists, if a leak occurs in a water purifier with the water level controller being inclined, it may result in the failure of the compressor, power supply line, PCB, etc. The analysis of the thermal diffusion pattern of water purifier compressors using a thermal image camera shows that its maximum temperature was approximately $80^{\circ}C$. In addition, its operating current was a maximum of 13 A and the system's operating current was approximately 1.7 A after the compressor was charged. It was found that the housing type power cable cover of the compressor had the effect of preventing electric shock but has poor flame resistance. Furthermore, the performance of the overload protector, PTC relays, etc., was excellent but they have potential for problems as metallic terminals were exposed, resulting in the potential of a safety related accident. The terminals and their surface damaged by the tracking showed a trace of carbonization and the resistance between terminals was measured to be approximately $8{\Omega}$. In addition, while the tracking was proceeding, the fuse and circuit breaker installed for system protection did not operate.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.183.2-183.2
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• 2010

본 개발에서의 해상용 풍력발전기는 크게 허브와 블레이드를 합한 상부 구조물, 전기 발전기와 연결 조인트의 중간구조물, 각종 제어 장치가 들어있는 제어박스로 나누어진다. 상부 구조물은 Circular Hub 타입의 Darrieus 형상으로 양력(lift)을 이용한 회전력이 발생하며, Circular Hub 타입은 기존의 허브와 블레이드를 연결하여주는 암(arm)에 의해 유발되는 항력토크를 최소화 하기 위한 신개념 형상설계가 이루어 졌으며, 저속에서 우수한 회전특성을 가진다. 이는 바람을 받아 기계적 에너지로 전환 하는 역할을 하며, 풍력발전기의 성능에 직접적인 영향을 미친다. 중간구조물의 전기발전기는, 상부에서 발생된 기계적 에너지를 이용하여 전기적 에너지로 전환 하는 역할을 수행한다. 이렇게 전환된 전기적 에너지는 하부의 제어박스를 거쳐서 해상용 부이(buoy)의 하단에 위치한 베터리 뱅크로 전달, 저장되어 부이에서 쓰이는 전력을 충당하게 된다. 한편 본 개발은 풍력발전기의 공력하중 해석과 로터블레이드의 설계, 풍력발전기의 구조, 진동해석, MPPT 제어컨트롤러와 Breaking controller, 풍동 및 차량시험을 통한 성능평가 및 분석 등의 순으로 개발을 수행하였다.

• 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.

• 한국비블리아학회지
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• 제24권4호
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• pp.91-98
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• 2013

이 연구의 목적은 포스 피드백이 비디오 게이머들의 게임결과에 미치는 영향을 두 가지 게임 콘트롤러에 따라 비교하는 한편, 게이머들의 포스 피드백에 관한 인식과 실제 그들의 게임결과가 일치하는지를 밝혀내고자 하는 것이다. 42명의 게이머들이 자동차 경주 비디오 게임에 참여하였고 그들의 게임결과를 변수들에 따라 분석하였다. 분석결과, 1) 포스 피드백이 비디오 게임에 미치는 영향은 콘트롤러의 종류에 따라 다르고, 2) 게이머들의 포스 피드백에 대한 인식과 실제 그들의 게임결과는 항상 일치하지는 않으며, 3) 흥미 요소가 게이머들의 게임결과에 큰 영향을 미침을 확인할 수 있었다.

• 한국컴퓨터산업학회논문지
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• 제2권12호
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• pp.1517-1522
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• 2001

기존의 전력 시스템 보호 장치는 아날로그 방식으로 고성능, 고기능화를 지향하는 전력 설비의 장치로는 동자의 신뢰도를 높일 수 없으며, 또한 배전용 전력 시스템의 중앙감시 및 제어 장치로 표준화시키지 못한 문제점이 있다. 수배전 보호장치와 비상용 발전 설비의 제어장치를 디지털 방식으로 전환시켜 집약적이고, 고성능의 전력 시스템 감시 및 제어 기능을 갖도록 한다. 전력 시스템의 동작 및 상태(전압, 전류, 전력, 위상 및 주파수)를 실시간 디지털 방식으로 계측하고 통신방식을 사용하여 감시하고 제어하는 통합 중앙 감시 및 제어장치 개발을 목적으로 한다. 이러한 전력 감시 설비를 마이컴 방식［1,2］을 채택하여 디지털 제어가 가능하며 집약적이고 고성능의 감시 및 제어기능［3］을 갖도록 하였다.

• 전력전자학회논문지
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• 제20권2호
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• pp.182-192
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• 2015

This study develops a digital control scheme with power factor correction for a front-end converter in an electric vehicle battery charger. The front-end converter acts as the boost-type switching-mode rectifier. The converter assumes the two roles of the battery charger, which include power factor control and robust charging performance. The proposed control scheme consists of a charging control algorithm and a grid current control algorithm. The scheme aims to obtain unity input power factor and robust performance. Based on the linear average model of the converter, a constant-current constant-voltage charging control algorithm that passes through only one proportional-integral controller and a current feed-forward path is proposed. In the current control algorithm, we utilized a second band pass filter, a single-phase phase-locked loop technique, and a duty-ratio feed-forward term to control the grid current to be in phase with the grid voltage and achieve pure sinusoidal waveform. Simulations and experiments were conducted to verify the effectiveness of the proposed control scheme, both simulations and experiments.

• 한국산업융합학회 논문집
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• 제17권2호
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• pp.42-53
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• 2014

Robust voice recognition (RVR) is essential for a robot to communicate with people. One of the main problems with RVR for robots is that robots inevitably real environment noises. The noise is captured with strong power by the microphones, because the noise sources are closed to the microphones. The signal-to-noise ratio of input voice becomes quite low. However, it is possible to estimate the noise by using information on the robot's own motions and postures, because a type of motion/gesture produces almost the same pattern of noise every time it is performed. In this paper, we propose an RVR system which can robustly recognize voice by adults and children in noisy environments. We evaluate the RVR system in a communication robot placed in a real noisy environment. Voice is captured using a wireless microphone. Navigation Strategy is shown Obstacle detection and local map, Design of Goal-seeking Behavior and Avoidance Behavior, Fuzzy Decision Maker and Lower level controller. The final hypothesis is selected based on posterior probability. We then select the task in the motion task library. In the motion control, we also integrate the obstacle avoidance control using ultrasonic sensors. Those are powerful for detecting obstacle with simple algorithm.

• Smart Structures and Systems
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• 제3권2호
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• pp.147-172
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• 2007

The present paper is concerned with the design of distributed sensors and actuators. Strain type sensors and actuators are considered with their intensity continuously distributed throughout a continuous structure. The sensors measure a weighted average of the strain tensor. As a starting point for their design we introduce the concept of collocated sensors and actuators as well as the so-called natural output. Then we utilize the principle of virtual work for an auxiliary quasi-static problem to assign a mechanical interpretation to the natural output of the sensors to be designed. Therefore, we take the virtual displacements in the principle of virtual work as that part of the displacement in the original problem, which characterizes the deviation from a desired one. We introduce different kinds of distributed sensors, each of them with a mechanical interpretation other than a weighted average of the strain tensor. Additionally, we assign a mechanical interpretation to the collocated actuators as well; for that purpose we use an extended body force analogy. The sensors and actuators are applied to solve the displacement tracking problem for continuous structures; i.e., the problem of enforcing a desired displacement field. We discuss feed forward and feed back control. In the case of feed back control we show that a PD controller can stabilize the continuous system. Finally, a numerical example is presented. A desired deflection of a clamped-clamped beam is tracked by means of feed forward control, feed back control and a combination of the two.

• Journal of Biosystems Engineering
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• 제31권4호
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• pp.305-314
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• 2006

Precision farming has been known as an environment friendly farming technology. This study was conducted to develop a variable-rate granule fertilizer applicator as an attempt for introducing the precision farming technologies to rice cultivation in Korea. In this paper, concept design process and manufacturing of prototype variable rate granule applicator was reported. For concept design, some design guide lines were selected. Based on the design guide line and some engineering knowledge, concept design was conducted. The designed prototype granule applicator was mounted at the rear of riding type cultivator for paddy field and had a 10m wide boom structure with pneumatic conveying and application system as well as 1GPS receiver, 1 granule hopper, 12 blow heads, 2 metering devices and 1 controller. The fertilizer applicator had 942 ka of weight, 740m of ground clearance and 1,117mm of center of gravity from the ground. The applicator was designed to be able to $34{\sim}428kg/ha$ of granule at $0.2{\sim}0.8m/s$ of fertilizer working speed.