• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.233-234
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• 2007

It is needed many images with different exposure to acquire high dynamic range (HDR) image of a scene using digital still camera. This paper proposed to acquire HDR image with small error using reduced number of image. Proposed method takes two pictures with different exposure and estimates dynamic range of scene using information two images, and takes three pictures with calculated proper exposure to acquire HDR image.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.164-172
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• 2001

Various HILS systems for developing and testing vehicle mechatronic systems have been proposed and constructed during the last few years. However, performance of those systems have not been evaluated in a systematic way. Based on the transfer function approach, this paper presents a method far evaluating performance such as stable dynamic simulation range of a proposed steering HILS system. In the evaluation, we have investigated effects of time delays that exist in the real-time dynamic simulation, additional actuators, and data transmission on the stable dynamic simulation range, simulation frequency range, and steering feel. This evaluation methodology may be useful to help engineers develop a HILS system for their own purposes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권11호
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• pp.4413-4425
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• 2020

In order to completely record all the information of realistic scenes, high dynamic range (HDR) images have been widely used in virtual reality, photography and computer graphics. A simple yet effective tone mapping method based on total variation is proposed so as to reproduce realistic scenes on low dynamic range (LDR) display devices. The structural component and texture component are obtained using total variation model in logarithmic domain. Then, the dynamic range of the structural component is compressed with an adaptive arcsine function. The texture component is processed by Taylor series. Finally, we adjust the saturation component using sigmoid function and restore the color information. Experimental results demonstrate that our method outperforms existing methods in terms of quality and speed.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2021년도 추계학술대회
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• pp.70-73
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• 2021

최근 영상 및 비디오 분야에 심층 신경망(DNN, Deep Neural Network)을 사용한 연구가 다양하게 진행됨에 따라 High Dynamic Range (HDR) 이미징 기술에서도 기존의 방법들 보다 우수한 성능을 보이는 심층 신경망 모델들이 등장하였다. 하지만, 심층 신경망을 사용한 방법은 큰 연산량과 많은 GPU 메모리를 사용한다는 문제점이 존재하며, 이는 심층 신경망 기반 기술들의 현실 적용 가능성에 제한이 되고 있다. 이에 본 논문에서는 제한된 연산량과 GPU 메모리 조건에서도 사용 가능한 다중 노출 HDR 경량화 심층 신경망을 제안한다. Kalantari Dataset에 대해 기존 HDR 모델들과의 성능 평가를 진행해 본 결과, PSNR-µ와 PSNR-l 수치에서 GPU 메모리 사용량 대비 우수한 성능을 보임을 확인하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2024년도 춘계학술발표대회
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• pp.18-19
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• 2024

High Dynamic Range 는 디지털 카메라에 내장된 영상 보정 장치인 Image Signal Processor 의 주요 기능 중 하나로서, 영상의 밝고 어두운 정도의 범위를 넓혀, 피사체가 더 또렷하게 보이도록 한다. 초당 수십 프레임을 촬영하는 경우, 실시간 보정처리를 위해 ISP 에 사용되는 기능 및 알고리즘은 신속성과 효율성이 요구된다. 본 연구는 ISP 에 적합한 HDR 알고리즘을 선정을 목표로 하여, Histogram Equalization 과 Contrast Limited Adaptive Histogram Equalization 을 소개한다. 이어 해당 알고리즘들을 컴퓨터 프로그래밍으로 구현, CMOS 이미지 센서를 통해 추출한 raw image 를 보정하여 각 알고리즘의 성능을 검토하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권2호
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• pp.731-763
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• 2017

In Underwater Linear Sensor Networks (UW-LSN) routing process, nodes without proper address make it difficult to determine relative sensor details specially the position of the node. In addition, it effects to determine the exact leakage position with minimized delay for long range underwater pipeline monitoring. Several studies have been made to overcome the mentioned issues. However, little attention has been given to minimize communication delay using dynamic addressing schemes. This paper presents the novel solution called Hop-by-Hop Dynamic Addressing based Routing Protocol for Pipeline Monitoring (H2-DARP-PM) to deal with nodes addressing and communication delay. H2-DARP-PM assigns a dynamic hop address to every participating node in an efficient manner. Dynamic addressing mechanism employed by H2-DARP-PM differentiates the heterogeneous types of sensor nodes thereby helping to control the traffic flows between the nodes. The proposed dynamic addressing mechanism provides support in the selection of an appropriate next hop neighbour. Simulation results and analytical model illustrate that H2-DARP-PM addressing support distribution of topology into different ranges of heterogeneous sensors and sinks to mitigate the higher delay issue. One of the distinguishing characteristics of H2-DARP-PM has the capability to operate with a fewer number of sensor nodes deployed for long-range underwater pipeline monitoring.

• 대한인간공학회지
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• 제29권6호
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• pp.875-887
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• 2010

The quantitative effectiveness of powered support surfaces such as APAM in preventing and treating pressure ulcers has not been sufficiently evaluated because of uncertainty of alternating pressure load input and lack of interpretation of dynamic perfusion characteristics of soft tissue. The aim was to verify the dynamic loading effects to sacral tissue perfusion characteristics from alternating set pressure changes. We developed integrated experiment system to supply alternating load to supinely positioned sacrum and concurrently measured $TcPO_2$, $TcPCO_2$ and air cell pressure. Ten aged subjects (5 female, 5 male) were tested with alternating set pressure 20, 30, 40, 50 and 60mmHg. From the dynamic perfusion response eight characteristic parameters were proposed such as average, minimum, maximum and perfusion range regarding to $TcPO_2$ and $TcPCO_2$. A one-way ANOVA was carried out to determine whether the manipulation of alternating set pressure had any effect on $TcPO_2$ and $TcPCO_2$. From the dynamic tissue perfusion response we found mean $TcPO_2$ decreased exponentially as alternating pressure load increased and perfusion range varied mainly because of minimum level change of $TcPO_2$. And perfusion range of $TcPCO_2$ affected by increase of maximum value of $TcPCO_2$. From the results we can get more strict insights about actual physiological dynamic tissue perfusion mechanism under alternating pressure load.

• Journal of Power Electronics
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• 제16권4호
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• pp.1598-1611
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• 2016

In some special occasions with strict size requirements, such as mine hoists, improving the design accuracy of the forced-air cooling systems of NPC three-level inverters is a key technology for improving the power density and decreasing the volume. First, a fast power-loss calculation method was brought. Its calculation principle introduced in detail, and the computation formulas were deduced. Secondly, the average and dynamic power losses of a 1MW mine hoist acting as the research target were analyzed, and a forced-air cooling system model based on a series of theoretical analyses was designed with the average power loss as a heat source. The simulation analyses proves the accuracy and effectiveness of this cooling system during the unit lifting period. Finally, according to an analysis of the periodic working condition, the maximum power-loss range of a NPC three-level inverter under multi cycle operation was obtained and its dynamic power loss was taken into the optimized cooling system model as a heat source to solve the power device damage caused by instantaneous heat accumulation. The effectiveness and feasibility of the optimization design based on the dynamic power loss calculation of the maximum power-loss range was proved by simulation and experimental results.

• 소성∙가공
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• 제7권6호
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• pp.620-630
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• 1998

Conventional hot forging and thixoforging of Al 7075 alloy have been compared with respect to microstructures, formability and hardness. Two distinctive temperature-strain rate ranges for hot forging of Al 7075 alloy were observed from the results of simple compression tests with strain rates of 10-3∼101 sec-1 in the temperatures between $250^{\circ}C$ and $500^{\circ}C.$ In the dynamic recovery range (low temperature-high strain rate range) multi-stage forging was necessary to form a complex shape part due to the lack of formability. In the high temperature-low strain rate range, in which dynamic recrystallization takes place a complex shaped park could be formed by single-stage forging. About 50% cold working in the SIMA process was necessary to get a fine and homogeneous microstructures. Microstructural study suggest that thixoforged Al 7075 part has fine grains and homogeneous microstructures. Its hardness number is almost same to that of conventional hot forged part after aging treatment.

• 한국멀티미디어학회논문지
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• 제15권1호
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• pp.9-17
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• 2012

최근 HDR (High Dynamic Range) 영상 렌더링을 위하여 다중 노출 영상 기반의 iCAM06 영상 재생 모델이 개발되었다. HDR 영상을 좁은 다이나믹 레인지를 갖는 디스플레이 장치에 출력하기 위해서는 톤 재현(tone reproduction) 또는 톤 맵핑(tone mapping) 과정을 거쳐야 하는데, HDR 렌더링 알고리즘을 대표하는 iCAM06은 출력 장치의 다이나믹 레인지에 영상을 재현하기 위해 S자 곡선 3 자극치 톤 압축(tone compression) 기법을 사용한다. 그러나 동일한 톤 맵핑 곡선의 사용으로 인한 톤 압축과정 중에서는 화이트 포인트 이동이 발생하는 단점이 있다. 그래서 본 논문에서는 3 자극치의 조명 영역의 입력에 대한 왜곡된 채널 이득을 보정하여 화이트 포인트 이동을 보상하는 방법을 제안하였다. 실험 결과는 제안한 방법이 iCAM06보다 정량 정성적으로 개선된 결과를 보임을 확인할 수 있다.