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PVDF 필름 기반 센서를 이용한 무구속적인 누운 자세 추정
서상원,황수환,윤희남,정다운,최재원,이유진,정도언,박광석,Seo, Sangwon,Hwang, Su Hwan,Yoon, Hee Nam,Jung, Da Woon,Choi, Jae Won,Lee, Yu Jin,Jeong, Do-Un,Park, Kwang Suk 대한의용생체공학회 2014 의공학회지 Vol.35 No.5
As body postures on bed affects various sleep related diseases, it is considered as important information when monitoring sleeping in daily life. Though there have already been a few approaches to monitor body postures on bed conventionally, the development for simple and unconstrained methods is still needed to realize the long-term daily monitoring. Focusing on the fact that ballistocardiogram changes depending on the body postures on bed, we developed a novel method to estimate body posturesusing extremely simple, film-type ballistocardiogram sensor which is based on polyvinylidene fluoride(PVDF) film. With 10 subjects, we performed two experiments. One was for an estimation test to show that body postures on bed can be estimated by ballistocardiogram, and the other was for a reproducibility test to present the feasibility of ballistocardiogram based body postures monitoring. To estimate body postures on bed, we made an individual template set of body postures by designating one ballistocardiogram (BCG) sample as a template in each postures. Then, we calculated Pearson's correlation coefficients between a sample and each templates and estimated the body posture of the sample by choosing a posture which corresponds to the most significant correlation coefficients. As a result, we estimated body postures on bed with 99.2% accuracy in average and found that the estimation using ballistocardiogram is reproducible.
서상원(Sangwon Seo),이재욱(Jaewook Lee),고한얼(Haneul Ko),백상헌(Sangheon Pack) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.2
연합학습에서는 서버와 클라이언트가 학습할 심층 모델을 교환하면서 학습을 진행한다. 하지만 최근 심층 모델의 크기가 점차 커짐에 따라 통신 부하가 급격히 증가하는 문제가 발생하였고, 이러한 문제를 해결하고자 통신 효율적인 연합 학습에 대한 연구가 활발히 진행되고 있다. 이에 따라 본 논문에서는 통신 효율적인 연합 학습 기법들에 대해 소개하고 해당 기법들의 한계점을 분석한다.
서상원(Sangwon Seo),정수웅(Soowoong Joeng),한윤상(Yunsang Han),최종수(Jongsoo Choi),이상근(Sangkeun Lee) 대한전자공학회 2013 전자공학회논문지 Vol.50 No.8
본 논문에서는 고해상도 영상에서 호모그래피를 효율적으로 추정하는 방법을 제안하였다. 호모그래피를 정확하게 추정하는 것은 영상 정합 기술에서 가장 중요한 부분이다. 하드웨어의 급속한 발전으로 고해상도 영상을 쉽게 취득 할 수 있게 되었지만, 데이터의 크기가 증가함에 따라 정확한 일치관계를 추정하는데 많은 계산량이 요구되었다. 또한, 고해상도의 영상에서 확률적으로 부정확한 호모그래피가 추정되는 문제가 발생하였다. 따라서 우리는 원 영상을 각 스케일별로 다운 샘플링한 다수의 영상을 생성하여 각 다운 샘플링된 영상에 해당하는 호모그래피를 추정한 후 투영 오차가 가장 작은 것을 선택하여 원 영상에 적용할 수 있게 보정할 수 있는 방법을 제안하였다. 또한, 영상을 정합하는 과정에서 기준 영상과 대상 영상의 색상 톤의 차이가 큰 경우에는 중첩영역의 지역 정보만을 이용하여 기준 영상과 대상 영상의 색상 톤을 일치시키는 방법을 제안하였다. 실험 결과 기존의 방법보다 3.2M 픽셀의 해상도 영상에서 약 3배, 8M 픽셀의 해상도 영상에서 약 5배 이상 빠른 결과를 얻을 수 있음을 확인하였다. 이는 입력 영상의 해상도가 커질수록 제안한 방법의 효과가 더 커진다는 것을 보여준다. An efficient homography estimation method for large sized images is proposed. Estimating an accurate homography is one of the most important parts in image stitching processes. Since hardwares have been advanced, it has been passible to take higher resolution images. However, computational cost for estimating homography has been also increased. Specifically, when too many features exist in the images, it requires lots of computations to estimate a correct homography. Furthermore, there is a high probability of obtaining an incorrect homography. Therefore, we propose a numerical method to extract the appropriate correspondences from several down-scaled images to estimate and compensate the homography numerically for restoring an original homography. Also, if there is an unbalance in color tone between the reference and the target images, we make them balanced by using local information of the overlapped regions. Experimental results show that proposed method is three times faster in 3.2 mega pixel images, five times faster in 8mega pixel images than the conventional approach. Therefore, we believe that the proposed method can be a useful tool to efficiently estimate a homography.
해외 선진국 규정 분석을 통한 국내 정부품질보증 효율성 향상 방안
서상원 ( Sangwon Seo ),노태주 ( Taejoo Roh ),변재현 ( Jai-hyun Byun ) 한국품질경영학회 2017 품질경영학회지 Vol.45 No.3
Purpose: Defense government agencies in the world continuously try to improve operational efficiency in government quality assurance activities. The purpose of this paper is to propose some suggestions to enhance efficiency of government quality assurance (GQA) activities based on the analysis of the current quality assurance methods of advanced foreign agencies such as DCMA and NATO. Methods: In order to propose new directions, reviews and analyses are executed. (1) Former research results in Korea for enhancing GQA are reviewed, and their limitations are addressed. (2) Updated policies and procedures of the US DCMA and NATO are reviewed and their advantages are presented. (3) Current GQA policies and procedures are contrasted with those of US DCMA and NATO. Results: Suggestions for efficient Korean GQA activities are given in several aspects: GQA paradigm shift, clarification of GQA methods, facility-wide GQA, risk management for suppliers, counterfeit mitigation policy, data collection and control. Conclusion: Reviews on the government quality assurance policies and procedures of DTaQ, DCMA, and NATO are executed and compared with each other. The results of this research are expected to be useful guidelines to improve GQA policies and procedures in Korea, making it possible to realize more efficient GQA activities in Korea.
서상원 ( Seo Sangwon ),허화만 ( Heo Hwaman ),장봉기 ( Jang Bongki ),황우열 ( Hwang Wooyull ),정일호 ( Jung Ilho ) 한국품질경영학회 2016 품질경영학회지 Vol.44 No.3
Purpose: Although the price reduction policy is established for military supplies, it is more focused on general military items. Therefore, it is hard to apply the current price reduction policy directly to the major weapon system. The purpose of this study is to develop an evaluation model which generates appropriate outputs for price reduction of military supplies. Methods: To improve the current policy, we first analyze the relevant policies of price reduction of similar organizations. We gather the opinions of related organization through survey including DAPA, Logistics Command, DTaQ and Defense industry companies. Then, we develop a price reduction model based on the analytic hierarchical process(AHP) method to find out important factors for price reduction. Results: The results of AHP analysis show that the important factors when applying price reduction of military supplies. From the analysis, the proposed method effectively generates the amounts of price reduction for the nonconformance items. Conclusion: The results of this research will be used as guidelines to improve military supplies policy of price reduction.
Taejoo Roh(노태주),Sangwon Seo(서상원) 한국산업경영시스템학회 2017 한국산업경영시스템학회지 Vol.40 No.3
Defense industries which require high reliability need an optimized quality management system with well-planned implementation. And the government should examine the overall status of defense industries, then establish practical policies with a proper support plan in required areas to upgrade the quality management level of manufacturers. Thus, DTaQ developed the model for 2 years from 2014, which specialized in quality management level analysis for defense industries. And a survey has been undertaken with that model by DTaQ and Korea Research Center in 2016. The surveyed companies randomly sampled among those which have more than 30 employees and delivery history over past 3 years, and finally 106 defense industries were selected. This paper present survey method and indexes for survey of defense industry quality management level. The survey was conducted in the order of planning, data collection and data processing, and the validity and reliability of the data were verified to increase objectivity of survey results. The survey contents mainly consist of system quality and management quality. System quality includes Product Development Management, Production Operation Management, supply chain quality management, Safety & Environment Management and Reliability Management, on the other hand, management quality includes Strategic Leadership, Human Resource Management, Customer Market Management and Information & Knowledge Management. Thus this proposes the current overall quality management status of the 106 defense industries and shows level differences by company sizes and manufacturing sectors based on the result of survey. Specifically, this paper enables to track the areas which need prompt government support with the policy directions to make quality management level higher. Therefore, it is expected that this can be used as reference data in establishing quality policies for military supplies in the future.