• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.407-408
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• 2020

본 논문은 SiC-MOSFET 기반 전기차용 인버터의 DC-Link 캐패시터 전기용량을 선정하는 방법에 대해 연구하였다. 인버터 시스템에 주로 사용되는 DC-Link 캐패시터는 안정적인 전원 및 고주파 전류 공급 등의 중요한 역할을 한다. 그러나 인버터가 고용량일수록 캐패시터 사이즈가 커지고 무게가 늘어나는 문제가 발생한다. 따라서, 차세대 전력 반도체 소자로 각광 받는 SiC-MOSFET의 높은 동작 주파수의 특성을 활용하여 캐패시터 소형화를 실현시켰다. 또한, PSIM 시뮬레이션을 통해 제안하는 연구의 타당성을 검증하고 Si-IGBT 인버터와 비교하여 그 효과를 입증하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.01a
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• pp.91-92
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• 2023

본 논문에서는 Yolov5와 Deepsort를 사용한 Tracking by detection을 구현하여 특정 영역을 통과하는 차량의 수를 집계하고, 각 차량의 추정속도를 계산하는 시스템을 구현한다. 실시간 객체 탐지 기능을 수행하는 Yolov5 모델의 학습에는 Kaggle의 개방 데이터인 '도요타 자동차 이미지'를 사용한다. 이미지 크기 640*640, 배치사이즈 16, Early stopping 플래그를 사용하여 학습했을때, Yolov5의 객체 탐지 성능은 정확도 98%, 정밀도 0.961, mAP 0.72을 보여주었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1292-1295
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• 2008

SOA Architecture 를 기반으로 한 SOiVA 의 Interactive Video 형식을 사용하여 개인정보를 유출하지 않고 전자 상거래를 가능하게 하는 Application 을 설계하고, 휴대폰, PDA, PMP 등 다양한 휴대 단말장치에서 공통적으로 기존의 웹사이트 시스템으로 최적화 시키지 못하는 문제점을 개선하여 다양한 사이즈의 디스플레이에서, 보다 효율적이고, 최적화된 서비스를 제공 가능케 하는 설계를 하고, SOiVA 서비스를 적용한 응용프로그램을 구현하였으며, 앞으로 발전 가능성을 제안하며, 향후 과제를 제시한다.

• Journal of the Korean institute of surface engineering
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• v.57 no.2
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• pp.98-104
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• 2024

In order to overcome the urban heat island effect, highly functional paint is attracting attention as a promising means by shielding heat on the structure (building) surface. When a paint was prepared containing nano-sized silica particles, the heat-insulating performance was relatively higher than that of paints with other sizes. In addition, developed paints showed enhanced properties such as chemical resistance and abrasion resistance test because of the presence of nano-sized silica included in functional paint.

• Journal of the Korea Society of Computer and Information
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• v.18 no.3
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• pp.1-10
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• 2013

In this paper, we propose a method of embedded linux light-weight to improve efficiency of application running on embedded systems. Three methods including fast booting scheme applying the Hibernation technique, JFFS2 file system optimization applying the Symbolic Link and virtual address mapping, kernel light-weight that guarantees the general purpose was applied. Since then check the system dependency and generate kernel image according to the target embedded kit. And embedded system performance of existing linux and linux which the method proposed in this paper was compared. In experimental result, the kernel size was 9.6% improved and the system booting time was 18% improved. And application processing speed on target embedded kit was improved 11% in the best case, 66% in the worst case. This result show that the light-weight method proposed in this paper is guarantee fast booting time and securing resources and it is good for the application processing speed improvement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.889-895
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• 2010

MIMO system generally requires more than one antenna at the communication device. However, many wireless devices are limited by size, cost or hardware complexity to one antenna. To overcome such restrictions, we used a new technique, called cooperative communication. We propose a new cooperative transmission strategy system using cross-layer coding method base on H-ARQ for optimal communication. Proposed cooperative H-ARQ system that can improve the above problems and can get the better performance. In proposed cooperative system with H-ARQ method, if the received signal from source node is satisfied by the destination preferentially, the destination transmit ACK message to both relay node and source node, and then recovers the received signal. In addition, if ARQ message indicates NACK message, relay node operates selective retransmission. Based on the simulation results in aspect to BER performance and throughput, the proposed method which combined cooperative system with H-ARQ based on cross-layer coding can improve spectral efficiency reliability of system compared with that of general one by one system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.5
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• pp.849-856
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• 2008

As the XML is used as the standard format for information delivery and exchange in various fields, the SVG is frequently used as a user interface or expression tool for the embedded system like an internet based mobile phone. The SVG file must contain additional information specifying the structure of the document and it consumes more transmission time than the actual data sent. The SMETA(Svg transmission MEthod using Semantic meTAdata) system[9] is a study to reduce the size of the SVG file by partitioning the SVG file to a minimal size and assigning meaningful meta data to each portion of the data. In this paper, instead of the meta data exchange method for reducing the size of the file exchanged in the existing SMETA system, we studied an improved version of SMETA system that analyzes the data for each user in the server system and only transmits the data that a user needs. In addition, through our simulation, we verified that it provides better performance than the existing system even if encryption is used.

• Journal of Digital Convergence
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• v.11 no.2
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• pp.287-297
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• 2013

In this paper, we propose an efficient variable-length radix-8/4/2 FFT architecture for OFDM systems. The FFT processor is based on radix-8 FFT algorithm and also supports radix-4 or radix-2 FFT computation. We are using efficient "In-place" memory access method to maintain conflict-free data access and minimize memory size. Also we replace a very large lookup table with a twiddle factor generator which consumes less area then a ROM-based lookup table. The proposed FFT processor performs variable-length FFT including 64, 256, 512, 1024, 2048, 4096 and 8192 points which cover all the required FFT lengths used in 802.11a, 802.16a, DAB, DVB-T, VDSL and ADSL.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.109-116
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• 2011

To measure the traffic pollutants with high temporal and spatial resolution under real conditions a mobile emission laboratory (MEL) was designed and built in KIST with close-cooperation with KIMM and Yonsei university. The equipment of the mini-van provides gas phase measurements of CO, NOx, $CO_2$, THC (Total hydrocarbon) and number density & size distribution measurements of fine and ultra-fine particles by a fast mobility particle sizer (FMPS) and a condensation particle counter (CPC). The inlet sampling port above the bumper enables the chasing of different type of vehicles. This paper introduces the construction and technical details of the MEL and presents data from the car chasing experiment of diesel and CNG city bus. The dilution ratio was increased rapidly according to the chasing distance. Most particles from the diesel city bus were counted under 300 nm and the peak concentration of the particles was located between 40-60 nm. However, the most particles from the CNG city bus were nano particle counted under 50 nm.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.199-202
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• 2008

고객의 통신 니즈가 다양해지고 통신 인프라가 대용량, 고속화 되고 단말이 지능화됨에 따라 이를 기반으로 IPTV의 셋탑, 컴퓨터 모니터, 이동통신 핸드폰이 이르기 까지 다양한 화면 사이즈의 단말을 통하여 서비스를 제공하고 있다. 이를 위해 원영상을 화면의 크기에 적합하게 크기를 변환하는 영상 리사이징 기술을 이용하게 되며, 그 방식은 DCT 방식과 공간 방식으로 나눌 수 있다. DCT방식은 원영상의 고주파 영역의 조정하여 크기를 변화하는 방식으로 열화는 최소화되나 DCT 변환을 위한 계산량이 많고 고정 크기 블록을 사용하므로 유연성이 떨어진다. 공간영역은 객관적인 평가에서 품질이 열화되더라도 시각적으로 눈에 민감한 영역의 변화를 최소화하는 것이다. 본 논문은 인간시각시스템을 기반으로 눈의 민간도가 높은 망막 이심율이 작은 영역에서는 DCT블록의 크기를 변화를 최소화시키고 망막이심율이 큰 영역에서는 블록의 변화를 크게 하는 가변 블록방식을 제안한다. 이를 통해 우수한 영상 품질을 확보하면서도 시각적으로 뛰어난 리사이징 영상을 얻을 수 있다.