• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.174-175
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• 2012

철도 분야에서도 환경 보호 및 에너지 절감을 위한 경량화 연구가 활발히 진행 되고 있다. 본 논문에서는 철도차량의 보조전원장치 경량화에 대해 설명 한다. 기존의 철도차량의 보조전원 장치는 내부 필터 리액터, 변압기 등이 중량의 상당한 부분을 차지 하고 있고, 이는 시스템 중량 저감을 위한 고민에서 가장 큰 위치를 차지 한다. 본 논문에서는 공진형 컨버터를 사용하고 스위칭 주파수를 높여 필터 리액터, 변압기 등을 경량화 하였다. 150kW급 시제품에 대한 모의해석과 실험을 통해 입증 하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.773-774
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• 2016

In this study, we perform the weight reduction and miniaturization of the shielding element that is applied for gamma-ray detectors for imaging of gamma-ray source. Through previous studies, we implemented a lead-based shielding element that represents the shielding effectiveness and performance of commercially available gamma-ray imaging apparatus similar to the shielding body. In this paper, we designed a tungsten-based shield for weight reduction and miniaturization than lead-based shield. We performed the MCNP simulation for shield design and then we obtained the results of reducing the weight of the 17% and 51% of the volume.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.39-40
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• 2023

본 논문은 딥러닝 기반의 소리 인식 모델을 기반으로 실내에서 발생하는 다양한 소리를 시각적인 정보로 제공하는 시스템을 위해 경량화된 CNN ResNet 구조의 인공지능 모델을 제시한다. 적용하는 경량화 기법은 모델의 크기와 연산량을 최적화하여 자원이 제한된 장치에서도 효율적으로 동작할 수 있도록 한다. 이를 위해 마이크로 컴퓨터나 휴대용 기기와 같은 임베디드 장치에서도 원활한 인공지능 추론을 가능하게 하는 모델을 양자화 기법을 적용한 경량화 방법들을 실험적으로 비교한다.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.73-83
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• 2005

This paper proposes both a novel tactile human-computer interface method and an improved algorithm for the wearable PC. Under the condition of Ubiquitous computing, the next generation PC aims at effective representation and integration of colors, brightness of light. sound, odor, taste and feelings. Also, it aims at human being centered man-machine interface. In spite of various functions of the wearable PC, for the convenience of possessing, hardware platform for the wearable PC should be small-sized and light weighted one. The main problems of making small sized PC are user interfaces, like keyboard, monitor and so on. The traditional user interfaces have critical limitations for reducing their size. In this paper, we propose a novel user input method and improved algorithm to constructing small sized, light weighted and wearable PC. And, we verify the effectiveness of suggested method and algorithm compared to the traditional algorithm.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.329-338
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• 2017

A recent trend of technical development in auxiliary-power-supplies (APS) is to replace 60Hz low frequency transformers with isolated type dc/dc converters. This paper introduces the technical trend in APS structures and proposes a power converter circuit suitable for high-efficient and light-weight APS. By utilizing the resonant converter, which achieves ZCS, to reduce switching losses, various types of APS structures (1-stage and 2-stage) are reviewed, and they are verified by simulation. The full-bridge resonant LLC converter is designed with a 1-stage power converting structure; the resonant converter topology is designed with a 2-stage power converting structure that has a pre-regulator converter to compensate for the wide input voltage range. Both a step-down converter and a step-up converter are designed and compared for the pre-regulator in the 2-stage structure. Operational characteristics are compared with simulation results and loss analyses are presented to proposes appropriate system structure and topologies.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.353-358
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• 2018

In this study, it is describe to an optimization analysis process for the weight reduction of the voltage converter in the electric vehicle charging systems. The optimization design is a technique that finds the optimal material distribution under a given material quantity constraint by combining the design sensitivity with the material properties and the mathematical optimization. Among the topology optimization, a lightweight design is performed by a solid isotropic material with penalization with simple formula and well-convergence. The lightweight design consists of three steps. As a first step, a finite element model for the basic design of the on-board voltage converter was constructed and static analysis was performed on the load. In the second step, the optimum shape is obtained for the lightweight by performing the topology optimization using the solid isotropic material with penalization applying the stiffness coefficient of the isotropic material to the static analysis result. As a final step, impact analysis was performed by applying a half-sinusoidal pulse shape impact load which satisfies the impact test standard of the vehicle-mounted part with respect to the optimum shape. In the topology optimization, the design domain was defined as the mounting bracket area, and the design technology was finally achieved by optimizing the mounting bracket to achieve a weight reduction of 20% over the basic design.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.948-949
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• 2016

In this study, we perform the structure change of the shielding this is applied for gamma-ray detectors for imaging of gamma-ray source. Through previous studies, we implemented the commercially available gamma-ray imaging apparatus similar to the shielding body but weight reduction, center of gravity moving of shield. In this paper, we changed a shield for motion control detectors efficient movement. We performed the MCNP simulation of shield design and then we obtained the results of reducing the weight of the 17% and moving of center of gravity the shield center.

• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.23-29
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• 2022

Recently, due to the increase in the use of Internet of Things (IoT) devices, the amount of data transmitted and processed to cloud computing servers has increased rapidly. As a result, network problems (delay, server overload and security threats) are emerging. In particular, edge computing with lower computational capabilities than cloud computing requires a lightweight authentication algorithm that can easily authenticate numerous IoT devices.In this paper, we proposed a key-agreement protocol of a lightweight algorithm that guarantees anonymity and forward and backward secrecy between IoT and edge devices. and the proposed algorithm is stable in MITM and replay attacks for edge device and IoT. As a result of comparing and analyzing the proposed key-agreement protocol with previous studies, it was shown that a lightweight protocol that can be efficiently used in IoT and edge devices.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.151-156
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• 2010

Monorail, with the cutting edge technology from EMU system, is small to medium sized transportation solution with bus size capacity, and one of key factors is to minimize size and weight. The Wolmi urban tour monorail, which is a center guide type first ever introduced in the world, is also consists minimizing size and weight of the propulsion system (inverter and motor), which generates considerable amount of heat. This study presents a solution of the structure and method of water cooling system of minimize the size and weight of high efficiency propulsion system, and an effective control method for energy saving.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.497-500
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• 1999

고속전철의 보조 전원 장치는 차량에 탑재되므로 소형화, 경량화 및 고신뢰성이 요구된다. 보조전원 장치중 Battery Charge는 고압의 직류전원(670Vdc)을 저압의 직류전원(83Vdc)으로 변환하여 객차(Trailer Car : 50kW) 및 동력차(Power Car : 10Kw)에 필요한 직류전원을 안정되게 공급하고 Battery Charger의 고장 발생 시를 대비해 Battery의 최적 충전상태를 유지해야 한다. 기술개발의 최종 목표는 고효율, 고신뢰성 밧데리 충전기 시스템 개발, EMI 저감, 부피와 무게의 소형경량화, 최적 스위칭 기술 및 회로 개발이다. IGBT에 대해 소프트 스위칭 기법을 사용하여 스위칭 손실 저감 및 소자의 스트레스의 저감으로 전력 변환 장치의 효율 향상과 소자의 신뢰성을 확보하였고, 스위칭 주파수를 높여 변압기나 인덕터등의 자기 소자의 크기를 줄였다. Battery Charger를 단일 모듈로 구성하기 보다 5kW 모듈을 여러개 조합한 다중모듈방법으로 병렬 운전하므로써 입출력 전류리플룰 감소시켰으며 시스템의 안정성과 신뢰성을 높일 수 있었다.