• Composites Research
• /
• v.35 no.6
• /
• pp.447-455
• /
• 2022

Currently, the problem of pollution of the marine environment by microplastics is emerging seriously internationally. In this study, to develop a lightweight portable microplastic collection device, the types and number of microplastics in 21 coastal areas nationwide in Korea were investigated. And CFRP (Carbon Fiber Reinforced Plastic), GFRP (Glass Fiber Reinforced Plastic), ABS (Acrylonitrile Butadiene Styrene copolymer) and aluminum were applied for design and analysis of microplastic collection device to have the durability, corrosion resistance and lightweight. As a result of sample collection and classification from the shore, it was confirmed that microplastics were distributed the most in Hamdeok beach, and the polystyrene was found to be mainly distributed microplastics. Particle information through coastal field survey and CFD (Computational Fluid Dynamics) analysis were used to analyze the flow rate and distribution of particles such as sand and impurities, which were applied to the structural analysis of the cyclone device using the finite element method. As a result of structural analysis considering the particle impact inside the cyclone device, the structural safety was examined as remarkable in the order of CFRP, GFRP, aluminum, and ABS. In the view of weight reduction, CFRP could be reduced in weight by 53%, GFRP by 47%, and ABS by 61% compared to aluminum for the cyclone device.

• Journal of Internet of Things and Convergence
• /
• v.9 no.1
• /
• pp.9-17
• /
• 2023

Deep learning with large amount of computations is difficult to implement on micro-sized IoT devices or moblie devices. Recently, lightweight deep learning technologies have been introduced to make sure that deep learning can be implemented even on small devices by reducing the amount of computation of the model. Quantization is one of lightweight techniques that can be efficiently used to reduce the memory and size of the model by expressing parameter values with continuous distribution as discrete values of fixed bits. However, the accuracy of the model is reduced due to discrete value representation in quantization. In this paper, we introduce various quantization techniques to correct the accuracy. We selected APoT and EWGS from existing quantization techniques, and comparatively analyzed the results through experimentations The selected techniques were trained and tested with CIFAR-10 or CIFAR-100 datasets in the ResNet model. We found out problems with them through experimental results analysis and presented directions for future research.

• Proceedings of the KIPE Conference
• /
• 2018.11a
• /
• pp.161-162
• /
• 2018

철도챠량에서 일반적으로 사용되는 상용전원은 보조전원장치(이하 SIV)로 불리는 전력변환장치로부터 공급된다. 본 논문에서는 LLC 공진형 컨버터를 적용하여 스위치의 영전압 스위칭(Zero-Voltage-Switching, ZVS)을 통해 높은 효율을 달성하고, 고속스위칭에 의해 인덕터, 커패시터, 트랜스포머와 같은 소자의 부피를 줄이고 시스템의 효율을 높여 기존의 보조전원장치보다 약 40%이상 소형 경량화가 가능한 보조전원장치에 대한 연구를 소개한다.

• Journal of Welding and Joining
• /
• v.22 no.4
• /
• pp.12-19
• /
• 2004

오늘날 IT산업의 괄목할 만한 성장으로 IT관련 휴대장비의 시장은 폭발적으로 증가하고 있다. 전통 제조업분야에서도 IT산업과 메카트로닉스의 발전 덕택에 경량화, 소형화된 전자소자나 전기소자 및 관련 센서, 액츄에이터를 활용할 수 있데 됨에 따라 기계 장비 및 장치가 점점 더 소형화되고 있다.(중략)

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.10a
• /
• pp.309-312
• /
• 2007

최근 임베디드 시스템에 대한 많은 연구들이 진행 중이다. 임베디드 시스템은 점점 소형화 추세로 가고 있다. DOM(Disk On Module)저장장치는 공간에 제한이 있는 응용프로그램이나 모바일 등의 기기에 사용할 수 있다. 본 논문에서는 DOM(Disk On Module) 메모리를 사용하여, 리눅스 기반의 커널을 탑재하고, DOM 메모리만으로 시스템이 구동될 수 있도록 한다. DOM(Disk On Module) 메모리의 용량 제한으로 인하여 소형 운영체제가 필수적이다. 이를 위해 본 논문은 기존의 리눅스 운영체제를 DOM 환경에 적합하도록 경량화시켜서 설계하였다. 리눅스 운영체제를 경량화한 수, DOM(Disk On Module)에 부트 로더의 한 종류인 LILO를 설치하여 DOM(Disk On Module)메모리상에서 새롭게 설계된 경량 리눅스 운영체제가 일반 리눅스 운영체제처럼 부팅될 수 있게 만들어 준다. 본 논문은 일반 리눅스 PC와 성능을 비교하는 실험을 수행하였다.

• Proceedings of the KIEE Conference
• /
• 2003.04a
• /
• pp.379-381
• /
• 2003

국내 전파법을 바탕으로 경량전철신호제어시스템용 무선통신장치와 무선데이터통신시스템간 간섭거리를 계산하였다. 무선데이터통신시스템이 실내에 설치되어 있는 경우 경량전철신호제어시스템용 무선통신장치를 사용하는 것이 문제없음을 화인하였다. 또한 실외의 경우에도 큰 문제없이 신호제어시스템용 분석장치를 사용할 수 있음을 확인하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.204-204
• /
• 2004

현재 정보통신의 강국으로 손꼽히고 있는 국내에서도 FPD(Flat Panel Display) 장치를 첨단산업 핵심 기술로 보고 기업 간에 치열한 기술경쟁을 벌이고 있는 실정이다. 현재 양산단계까지 접어든 TFT-LCD(Tin Film Transistor Liquid Crystal Display)와 PDP(Plasma Display Panel)는 경량화, 박형화 등의 장점으로 전자업계에서 최고의 캐시카우(Cash Cow)로 부각되고 있으며, 특히 소비자들의 대화면 선호도의 증가 추세에 힘입어 LCD보다는 콘트라스트 비(Contrast Ratio)와 시야각(View Angle) 측면에 있어 FPD 장치의 대면적화 관점에서 유리한 PDP가 다소 우위를 보이고 있는 추세이다.(중략)

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.3
• /
• pp.283-289
• /
• 2015

In this study, the lightweight design of a brake bracket for a composite bogie was studied by considering two brake bracket models with thicknesses of 12t and 9t, respectively. For achieving this goal, finite element analysis and topology optimization were conducted. Firstly, the largest cross-sectional areas of the vertical and horizontal plates of the brake bracket were selected as the design variables. As the constraint, the Z-axis displacement of the brake bracket was increased by 2.5 units from the initial displacement value. The minimum volume fraction of the design regions was chosen as the objective function. The full model comprised a composite bogie frame and brackets attached together. However, to reduce the analysis time, 1D beam elements were used instead of the composite bogie frame by ensuring its equivalence with the full model. The result revealed that the weights of the 12t and 9t models of the brake bracket were reduced to 60 kg and 31 kg, respectively.

• The Optical Journal
• /
• s.109
• /
• pp.24-27
• /
• 2007

A/F 카메라모듈이 적용되기 위해서는 A/F구동 렌즈의 크기가 휴대폰의 경량화.슬림화에 대응되어야 한다. 초기에는 구동장치보다 카메라모듈 자체에만 신경을 썼었다. 그러나 지금은 그 구동원이 점점 작아져 거의 고정초첨 카메라 모듈 크기와 비슷하게 되었다. 따라서 필자는 2008년에는 A/F가 기본 사양이 될 것으로 강하게 믿고 있다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.8
• /
• pp.1588-1596
• /
• 2015

In the Internet of Things (IoT), resource-constrained devices such as sensors are capable of communicating and exchanging data over the Internet. The IETF standard group has specified an application protocol CoAP, which uses UDP as a transport protocol, allows such a lightweight device to transmit data. Also, the IETF recommended the DTLS binding for securing CoAP. However, additional features should be added to the DTLS protocol to resolve several problems such as packet loss, reordering, fragmentation and replay attack. Consequently, performance of DTLS is worse than TLS. It is highly required for lightweight devices powered by small battery to design and implement a security protocol in an energy efficient manner. This paper thus discusses about DTLS performance in the perspective of energy consumption. To analyze the performance, we implemented IEEE 802.15.4 based test network consisting of constrained sensor devices in the Cooja simulator. We measured energy consumptions required for each of DTLS client and server in the test network. This paper compares the energy consumption and amount of transmitted data of each flight of DTLS handshake, and the processing and receiving time. We present the analyzed results with regard to code size, cipher primitive and fragmentation as well.