Ajou Motor College

This study analyzes the lifetime characteristics and degradation behavior of lithium-ion batteries under increasing charge–discharge cycles. The experiment focused on RE (Real Part), IM (Imaginary Part), and DCIR Degradation% (Direct Current Internal Resistance Degradation). The RE increased from 0.0023 Ω at the initial state to 0.00293 Ω after 1200 cycles, representing a 28% rise, with a sharp acceleration after 400 cycles due to interfacial resistance buildup and electrolyte decomposition. The IM shifted from negative to positive values, indicating delayed electrochemical reactions and enhanced inductive behavior. A pronounced transition occurred between 400 and 800 cycles, confirming this range as a critical phase of performance degradation. Correlation analysis between SoH (State of Health) and DCIR Degradation% showed that while SoH decreased slightly from 100% to 87.3%, DCIR Degradation% increased significantly to 137.8%, indicating that internal resistance growth is the dominant cause of aging. When SoH falls below 70%, the battery reaches its effective end-of-life, accompanied by severe heat generation and power loss. In conclusion, the combined analysis of RE, IM, and DCIR Degradation% demonstrates that accumulated internal resistance is the key factor determining battery lifetime. Stabilizing the SEI layer, reinforcing electrode structures, and improving electrolyte stability are essential strategies for extending battery durability.

This paper experimentally investigates the control performances of a piezostack actuator direct-drive valve (PADDV) operating at high temperatures. In this study, the PADDV system is designed based on special specifications featuring a high operating temperature (150 °C) and wide control bandwidth (200 Hz). After manufacturing the PADDV with design limitations such as size and maximum input voltage to the piezostack actuator, the displacement of a spool located inside the valve system, which is directly related to the flow rate, is controlled at several different temperatures and motion frequencies. In order to undertake this, the PADDV system is installed inside a heat chamber equipped with air vessels and pneumatic–hydraulic cylinders. The piezoelectric actuator is partially insulated using an aerogel to prevent permanent damage due to high temperatures above 120 °C, which is higher than the Curie temperature. To control the valve system, a PID (proportional–integral–derivative) controller is realized in which control gains are properly tuned using fuzzy logic according to the change of temperature and frequency. It is shown from the experimental results that the proposed PADDV with thermal insulation can provide the target dynamic motion of 200 Hz at 150 °C by implementing the fuzzy-based PID controller.

As medical technology has been developing, patients’ information (medical information, disease information, etc.) has been diversely used in medical services so that patients’ biometric information can be used for remote diagnosis and examinations. However, since the complexity and uncertainty of patient treatment have been increasing, doctors’ burden due to hospital work has been also increasing. In the present paper, an analytic hierarchy process based patient information management scheme is proposed that can synchronize diverse medical devices used for patient treatment to hierarchically manage patients’ disease information. The purpose of the proposed scheme is to analyze the correlations of medical devices used in medical treatment of patients to induce hierarchical management of patients’ disease information through triangle fuzzy of pairwise comparison scales for medical treatment and efficiently perform not only hospital administrative work but also patients’ disease analysis and treatment. In addition, using the patients’ disease information collected through diverse medical devices, the proposed scheme improves the efficiency of patient treatment methods so that hospitals can calculate the importance of treatment standards in order to hierarchically identify treatment standards. Furthermore, since the proposed scheme enables efficiently selecting treatment methods for patients’ diseases, it has a characteristic of being capable of efficiently improve the ambiguousness and inaccuracy of treatment judgments and treatment compared to existing disease treatment methods. According to the results of performance evaluation, the proposed scheme improved work efficiency by 11.9% over existing techniques and reduced medical device administration costs by 10.9%. Furthermore, the proposed scheme improved patients’ satisfaction with treatment by 23.6%.

Magnetorheological (MR) devices in vehicle applications and robotic systems require both consistent control performance and reliable operation. However, corrosion of iron particles in MR fluid may occur during long-time operation. This corrosion behavior can significantly affect the performance and reliability of application devices or systems utilizing MR fluids. This study experimentally investigates the effect of the MR particle corrosion on the performance of MR fluids in terms of the field-dependent yield stress magnitude and shear stress controllability. MR particles are first corroded by two different liquids; water–sodium chloride solution and water–calcium chloride solution. The resulting MR particles are examined by scanning electron microscopy and their molar ratios are analyzed by energy dispersive x-ray analysis. Using the corroded MR particles, MR fluid is synthesized for evaluation of the effects on its characteristics. A rotational viscometer is used to measure the field-dependent shear stress and response time. The measured results are compared between the original MR fluid composed of the non-corroded iron particles and the MR fluid composed of the corroded iron particles. In addition, the effect of the corroded particles in MR fluid on the shear stress controllability is investigated in the time domain.

Abstract Pneumatic motors are quite attractive for many applications because of their competitive price, light-weight, easy assembly, safety in hazardous areas as well as other features, such as a good force/weight ratio and operationin exceptionally harsh environments. In contrast to these advantages, pneumatic motors have limited use in applications, particularly those requiring a fast and precise response. These undesirable characteristics are due to the high compressibility of air and from the nonlinearities in pneumatic systems. This paper presents the sliding modecontroller based on 3-loop(SMCB3L), which increases the load stiffness to control the rotation angle of a pneumatic motor. The characteristics for the step responses and load disturbances of the proposed controller were compared withthe conventional PID controller. The experimental results showed that a properly designed SMCB3L is capable ofhigh positioning accuracy within ±0.05mm. Furthermore, the load stiffness of the SMCB3L can be improved 3.5 foldcompared to that of PID controllers.

In this work, 4 degrees-of-freedom (DOF) haptic master featuring electrorheological (ER) fluid is proposed and integrated with a slave. Using an ER fluid, the haptic master is devised which can generate a repulsive force/torque with the 4-DOF motion and provide stimulus information to operator. For realization of master-slave MIS system, an encoder is installed with the ER haptic master to establish the MIS master system. The motion command of the haptic master is realized by slave surgery robot. In order to follow the motion of the haptic master, the mechanism of slave surgery robot is devised. Accordingly, the haptic master-slave system is established by incorporating the slave robot with the haptic master device in which the repulsive force/torque and desired position are transferred to each other. In order to obtain the desired torque trajectories, a sliding mode controller (SMC) is designed and implemented. It has been demonstrated that the desired effective torque tracking control performance is well achieved using the proposed master-slave system.

본 연구는 옥외 광고를 위한 LCD 패널용 콘솔(이하 콘솔'이라 한다.)"의 내부온도 제어를 위한 냉각장치의 제어기 설계에 관하여 다루고 있다. 콘솔은 본 연구진에 의하여 개발된 것으로 냉각장치는 열전소자를 이용하여 사용조건에 적합하도록 설계하였다. 아울러 본 연구는 콘솔이 우수한 성능을 발휘할 수 있도록 제어전략과 그 방안을 제안하고자 한다. 본 연구의 구성은 먼저 시스템의 구조와 설계조건에 대하여 정의하였다. 이어서 동적 특성을 결정하는 파라미터를 측정한 후 분석을 위하여 시스템을 수식 모델링하였다. 끝으로 제어전략을 수립한 후 수식모형을 이용하여 제어기의 성능 검사를 위한 시뮬레이션을 실시하고 기존의 제어기 성능과 비교분석하였다. 본 연구의 목적은 비교분석을 통하여 보다 개선된 제어방식을 제시하는 것이다. This study dealt with the controller design of the cooling system for controlling the inside temperature of the LCD panel console(the rest console') using as an outdoor billboard. The cooling performance of the LCD console that had been developed by the preceding research, was insufficient in the performance of the controller. In order to improve the performance of the system, in this study defined the structure and the design condition of the system first, after measured the parameters having influence on the dynamic characteristics, and developed the mathematical model for the analysis of the system. Finally planned a controlling scheme of the system and simulated the controller for the performance checking, compared the performance of this system controller with the preceding one. The purpose of this study is the presentation of the more improving method for the system control.

When circulated air passes through the cooling coil in an air-conditioning system, the air is over-cooled to eliminate the moisture and decrease the temperature. The cooled air is then reheated to recover the temperature. The purpose of the present study was to evaluate the performance of a cooling/reheating system with regard to both cooling and reheating energy savings affected by exchanging heat between the cooled air and the reheated air with a compact heat exchanger. The thermal and dehumidification behaviors of the system were evaluated experimentally and then compared with simulation data. The results show that the energy saving rate was as high as 50% under the present experimental conditions and was affected by the face velocity of the heat exchanger, the inlet temperature, the inlet humidity ratio, and the effectiveness of heat exchanger. Furthermore, the experimental data were found to be in fairly good agreement with the simulation data.

본 연구의 목적은 Display 산업의 중요성에 주목하여 옥외 광고를 위한 LCD 패널용 콘솔(이하 'LCD 콘솔'이라 한다.)을 개발하는데 있다. 본 연구의 핵심 과제는 LCD 콘솔의 내부온도를 제어할 수 있도록 해주는 냉각시스템(Cooling System)을 개발하는 것이다. 냉각시스템은 상용화되어 있는 냉각휀(Cooling Fan), 히트싱크(Heat sinks), 열전소자(Thermo Electronic Module) 등의 제품들을 시스템적으로 통합시키는 응용기술로서 통계적 검정기법을 적용하여 개발되었다. 본 연구는 먼저 냉각시스템을 설계/제작한 후 실험을 통하여 냉각시스템 제어에 필요한 인자들의 설정 값들을 구하는 과정을 보였다. 이어서 개발된 냉각시스템을 이용하여 46인치 LCD Panel이 탑재된 LCD 콘솔을 설계/제작하고 실험을 통하여 완성품 LCD 콘솔의 성능을 확인하는 과정을 보였다. The development of the console for exterior advertizing LCD Panel(LCD Console) is the purpose of this study with regard to importance of display industry. In this study, the most important point is to develop the cooling system for LCD Console. It is developed by using systematic application techniques and statistical tests and analysis to integrate commercial components, cooling fan, heat sink, thermo electronic modules etc, of it. This study, at first, shows design/manufacturing process of the cooling system and the setting process of control factors to control through experimentation. Next, after constructing the complete console, 46 inch LCD Panel and the cooling system are built in, the performance test of it is shown through experimentation.