• Journal of Aerospace System Engineering
• /
• v.4 no.3
• /
• pp.6-16
• /
• 2010

After the first successful Apollo program, many countries around the world launched their own programs for exploring the moon. This paper surveys various navigation and attitude control systems of several past lunar exploration programs for the purpose of preparing a program for the first Korean lunar probe. For this first we investigate successful programs by introducing the sensors and actuators used for these programs, particularly focusing on those of Clementine and SMART-1 of USA and EU, respectively. Then based on the study, we suggest the necessary components of navigation and attitude control systems suitable for our lunar probe program.

• Journal of Information Processing Systems
• /
• v.15 no.1
• /
• pp.47-54
• /
• 2019

This study is concerned with the mechanism and structure of an optical microscope and an automatic multi-focus algorithm for automatically selecting sharp images from multiple foci of a cell. To obtain precise cell images quickly, a z-axis actuator with a resolution of $0.1{\mu}m$ was designed to control an optical microscope Moreover, a lighting control system was constructed to select the color and brightness of light that best suit the object being viewed. Cell images are captured by the instrument and the sharpness of each image is determined using Gaussian and Laplacian filters. Next, cubic spline interpolation and peak detection algorithms are applied to automatically find the most vivid points among multiple images of a single object. A cancer cell imaging experiment using propidium iodide staining confirmed that a sharp multipoint image can be obtained using this microscope. The proposed system is expected to save time and effort required to extract suitable cell images and increase the convenience of cell analysis.

• Smart Structures and Systems
• /
• v.23 no.4
• /
• pp.319-327
• /
• 2019

Continuous rotating SMA actuators require motion conversion mechanisms, so their structure is relatively complex and difficult to realize the miniaturization. Here, a new type of continuous rotating actuator driven by SMA is proposed. It combines the movable tooth drive with SMA drive. The structure and working principle of the integrated movable tooth drive system is introduced. The equations of temperature, stress and strain of memory alloy wires, and the output torque of drive system are given. Using these equations, the temperature, the output forces of the SMA wires, and output torque of the drive system are studied. Results show that the compact drive system could give large output torque. To obtain large output torque plus small fluctuation, large eccentricity and small diameter of the SMA wire should be taken. Combined application of ventilation cooling and high current can increase the rotary speed of the drive system.

• Elastomers and Composites
• /
• v.56 no.2
• /
• pp.57-64
• /
• 2021

This paper reviews recent developments and applications of dielectric elastomers (DEs) and suggests various techniques to improve DE properties. DEs as smart materials are a variety of electro-active polymers (EAPs) that convert electrical energy into mechanical energy and cause a large deformation when a voltage is applied. The dielectric constant, modulus, and dielectric loss of DEs determine the efficiency of deformation. Among these, the dielectric constant significantly affects their performance. Therefore, various recent approaches to improve the dielectric constant are reviewed, including the enhancement of polarization, introduction of microporous structures in the matrix, and introduction of ferroelectric fillers. Furthermore, the basic principles of DEs are examined, as well as their various applications such as actuators, generators, sensors, and artificial muscles.

• Korean journal of aerospace and environmental medicine
• /
• v.30 no.3
• /
• pp.100-107
• /
• 2020

Internet of Things (IoT) is a technology that communicates data between devices, which are things, using an embedded sensor connected through network backbone such as the internet. Here, data communication technology, sensor technology, and actuator (interface) technology are fused into IoT and it turns devices into smart things. As a result, vast sized data are being generated and that data is being processed into useful actions that can control the things that are devices to make our lives much fruitful. Nowadays, the IoT, early defined as Machine-to-Machine (M2M) connection, becomes a key technology powered by growing innovation of wireless communication trends in the internet connectivity through mobile networking. This paper gives an overview of Internet of Things and brief information about major technologies and its applications in various fields focusing aviation.

• Annual Conference of KIPS
• /
• 2021.11a
• /
• pp.1020-1023
• /
• 2021

본 논문에서는 기존의 책상에서 발생하는 문제점을 개선하고 효율적인 공부를 할 수 있도록 도와주는 "학습 능률을 높이는 스마트 책상" 시스템을 제안한다. 제안하는 시스템의 주요 기능은 다음과 같다. 첫째, 아두이노와 Linear actuator를 사용하여 책상의 높낮이와 책받침의 각도를 조절한다. 둘째, 심박 센서를 통해 사용자의 집중도를 확인하고 이와 연동된 어플리케이션으로 각종 센서와 모듈을 제어하여 최적의 공부환경을 조성한다. 셋째, 책상 위 모든 동작이 어플리케이션을 통해 자동으로 수행되어 Human task를 감소시킨다. IoT 기술과 집중력 관리 알고리즘을 활용한 제안 시스템을 통해 학습자의 책상 앞 올바른 자세 교정과 학습 시 높은 집중력을 유지시키는데 도움을 줄 수 있을 것으로 기대된다.

• Annual Conference of KIPS
• /
• 2023.11a
• /
• pp.786-787
• /
• 2023

대규모 행사에서 압사 예방을 위해 스마트 IoT 조끼 시스템을 개발했다. 일반 사용자들이 해당 조끼를 착용해 긴급 상황 발생 즉시 행사 관리자에게 정보를 전송하고 동시에 Linear Actuator를 활용해 개발한 에어백 기능으로 인명피해 사고를 보다 예방할 수 있다.

• Coupled systems mechanics
• /
• v.13 no.2
• /
• pp.171-186
• /
• 2024

In the present paper, thermal buckling characteristics of functionally graded rectangular plates made of porous material that are integrated with surface-bonded piezoelectric actuators subjected to the combined action of thermal load and constant applied actuator voltage are investigated by utilizing a Navier solution method. The uniform temperature rise loading is considered. Thermomechanical material properties of FGM plates are assumed to be temperature independent and supposed to vary through thickness direction of the constituents according to power-law distribution (P-FGM) which is modified to approximate the porous material properties with even and uneven distributions of porosities phases. The governing differential equations of stability for the piezoelectric FGM plate are derived based on higher order shear deformation plate theory. Influences of several important parameters on the critical thermal buckling temperature are investigated and discussed in detail.

• KIPS Transactions on Computer and Communication Systems
• /
• v.11 no.6
• /
• pp.193-204
• /
• 2022

In a smart factory environment in a small and medium-sized enterprise (SME) environment, sensors and actuators operating on actual manufacturing lines, programmable logic controllers (PLCs) to manage them, human-machine interface (HMI) to control and manage such PLCs, and consists of operational technology server to manage PLCs and HMI again. PLC and HMI, which are in charge of control automation, perform direct connection with OT servers, application systems for factory operation, robots for on-site automation, and production facilities, so the development of security technology in a smart factory environment is demanded. However, smart factories in the SME environment are often composed of systems that used to operate in closed environments in the past, so there exist a vulnerable part to security in the current environment where they operate in conjunction with the outside through the Internet. In order to achieve the internalization of smart factory security in this SME environment, it is necessary to establish a process according to the IEC 62443-4-1 Secure Product Development Life cycle at the stage of smart factory SW and HW development. In addition, it is necessary to introduce a suitable development methodology that considers IEC 62443-4-2 Component security requirements and IEC 62443-3 System security requirements. Therefore, this paper proposes an application plan for the IEC 62443 based development security process to provide security internalization to smart factories in an SME environment.

• Smart Structures and Systems
• /
• v.19 no.2
• /
• pp.181-194
• /
• 2017

In order to investigate the interface debonding defects detection mechanism between steel tube and concrete core of concrete-filled steel tubes (CFSTs), multi-physical fields coupling finite element models constituted of a surface mounted Piezoceramic Lead Zirconate Titanate (PZT) actuator, an embedded PZT sensor and a circular cross section of CFST column are established. The stress wave initiation and propagation induced by the PZT actuator under sinusoidal and sweep frequency excitations are simulated with a two dimensional (2D) plain strain analysis and the difference of stress wave fields close to the interface debonding defect and within the cross section of the CFST members without and with debonding defects are compared in time domain. The linearity and stability of the embedded PZT response under sinusoidal signals with different frequencies and amplitudes are validated. The relationship between the amplitudes of stress wave and the measurement distances in a healthy CFST cross section is also studied. Meanwhile, the responses of PZT sensor under both sinusoidal and sweep frequency excitations are compared and the influence of debonding defect depth and length on the output voltage is also illustrated. The results show the output voltage signal amplitude and head wave arriving time are affected significantly by debonding defects. Moreover, the measurement of PZT sensor is sensitive to the initiation of interface debonding defects. Furthermore, wavelet packet analysis on the voltage signal under sweep frequency excitations is carried out and a normalized wavelet packet energy index (NWPEI) is defined to identify the interfacial debonding. The value of NWPEI attenuates with the increase in the dimension of debonding defects. The results help understand the debonding defects detection mechanism for circular CFST members with PZT technique.