기후변화의 시대에 지속가능한 집단에너지 사업의 발전 방향과 전망

임용훈 한국에너지학회 2019 한국에너지공학회 학술발표회 Vol.2019 No.5

Optimization-based Fiber Orientation Modeling for Computational Mitral Valve Evaluation

임용훈,Frederick Mun,김형건 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

Biomechanical response of the mitral valve (MV) leaflet tissue is closely related to the characteristics, density, and orientation of the collagen fibers. Alterations of collagen fiber arrangement have a direct influence on the biomechanical characteristics of the MV leaflets leading to physiologic deterioration. In this study, we describe a nonlinear optimization technique to define fiber orientations across the MV posterior leaflet. A symmetric MV model consisting of the saddle-shaped annulus, the anterior leaflet, and the triscalloped posterior leaflet was modeled. The posteromedial half portion of the posterior leaflet was segmented and meshed. An unconstrained nonlinear multi-objective optimization protocol with lower and upper boundaries was developed to determine realistic collagen fiber distribution across the posterior leaflet. In the cleft region, the optimization-based fiber orientation modeling method demonstrated a sharp change of fiber orientation near the annular region followed by a slow adjustment of fiber orientation near the free leaflet margin, which corresponds well to the native MV leaflet tissue. Fiber distribution in the cleft region revealed a large difference between the optimization and the linear interpolation methods. This optimization strategy has the potential to effectively model the natural fiber orientation across the MV leaflets for improved computational evaluation of MV function.

The comparison of joint kinematic error using the absolute and relative coordinate systems for human gait

임용훈,최안렬,민경기,금동혁,최창현,문정환,이상식 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.1

Minimizing artifacts from skin movement is vital for acquiring more accurate kinematic data in human movement analysis. There are several stages that cause skin movement artifacts and these stages depend on the selection of the reference system, the error reduction method and the coordinate system in clinical gait analysis. Due to residual errors, which are applied to the Euler and Bryant angle methods in each stage, significant cumulative errors are generated in the motion analysis procedure. Thus, there is currently a great deal of research focusing on reducing kinematic errors through error reduction methods and kinematic error estimations in relation to the reference system. However, there have been no studies that have systematically examined the effects of the selected coordinate system on the estimation of kinematic errors, because most of these previous studies have been mainly concerned with the analysis of human movement using only the human models that are provided in the commercial 3D motion capture systems. Therefore, we have estimated the differences between the results of human movement analyses using an absolute coordinate system and a relative coordinate system during a gait, in order to establish which system provides a more accurate kinematic analysis at the ankle joint. Six normal adult subjects with no neurological or orthopedic conditions, lower extremity injuries, or recent history of lower extremity surgery were used in this study. The analysis was conducted at a walking speed of 1.35m/s. For the clinical estimation, we used a cardinal plane based on the segmental reference system and the differences were plotted on the planes. From this analysis, when a relative coordinate system was in the gait analysis, the average kinematic error occurring during the gait was determined to be 13.58mm, which was significantly higher than the error generated with an absolute coordinate system. Therefore, although the relative coordinate system can also be used to calculate the ankle joint center during the clinical gait analysis, the absolute coordinate system should be employed in order to obtain more accurate joint kinematic data. In addition, the results from this study can be used as a basis to select an appropriate coordinate system with regards to the diagnostic accuracy level required for various kinds of gait disorders.

에너지효율 분야에서의 집단에너지 역할과 발전방향 고찰

임용훈 한국에너지공학회 2012 한국에너지공학회 학술발표회 Vol.2012 No.4

RFID 데이터 이벤트 처리 기법 연구

임용훈,현덕화,이범석,주성호,최효열,김태경 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7

RFID 기술은 모든 사물에 태그를 부착하여 전파를 이용하여 사물에 대한 정보를 자동으로 인식하고 이를 실시간으로 네트워크에 연결하여 정보를 관리하는 기술이다. RFID에 기반한 어플리케이션은 사용자의 요구에 의한 용용프로그램과 달리 태그의 인식이 프로그램 실행을 발생하게 하므로 실시간이벤트 처리, 실시간 이벤트 모니터링을 처리가 가장 중요하다. 하지만 리더로부터 인식된 태그 데이터가 아무런 정제 작업 없이 직접 용용어플리케이션에 전달되게 된다면 불필요한 연산을 수행하게 되어 성능이 저하되는 요인이 된다. RFID 미들웨어의 주된 역할은 리더기와 응용시스템 사이에 데이터들을 전송하는데 있다. 따라서 태그 데이터 처리 기능을 통해 응용 시스템에 신뢰성 있는 정보제공은 미들웨어에서 중요한 기능을 수행하게 된다. 본 논문에서는 응용시스템에 신뢰성 있는 데이터 전송에 필수 기능인 불필요한 이벤트를 제거하는 필터링 기능을 위한 프레임워크 설계, 구현하였다.

ERGONOMIC AND BIOMECHNICAL ANALYSIS OF AUTOMOTIVE GENERAL ASSEMBLY USING XML AND DIGITAL HUMAN MODELS

임용훈,문정환,김건연,노상도 한국자동차공학회 2008 International journal of automotive technology Vol.9 No.6

Automotive general assembly requires many manual assembly operations to be carried out by human workers. Ergonomic analysis is an important part of the design and evaluation of products, jobs, tools, machines and environments for safe, comfortable and effective human functioning. Most recent researches have involved the evaluation of working conditions to prevent work-related musculoskeletal disorders. The majority of previous research on automotive companies has mainly considered the results of ergonomic analyses such as RULA (Rapid Upper Limb Assessment), REBA (Rapid Entire Body Assessment) and OWAS (Ovako Working Posture Analysis System). Analysis of static posture including reachability, clearances for arm, hand and tool has also been used to evaluate working conditions. However, in addition to static posture analysis, a biomechanical analysis in dynamic conditions should also be conducted. There are no integrated frameworks or standard schema for ergonomic analysis using digital human models in digital environments. The purpose of this paper is to propose a new framework for the evaluation of working conditions by ergonomic and biomechanical analysis using digital models based on XML standard schema, including: products, processes, manufacturing resources and human workers. This paper presents the analysis results using the proposed framework for automotive general assembly operations. We propose a new framework for the evaluation of the assembly operations and their environments. Then we apply a digital human model to the dynamic simulation of general automotive assembly operations based on standard schemas in XML and PPRH (Product, Process, Resource and Human). Using PPRH information based on a standard XML schema to analyze the ergonomic and biomechanical results, the engineer can visualize, analyze and improve assembly operations and working environments in automotive general assembly shops using digital models.

스마트그리드 보안 위협 및 전략

임용훈 한국조명·전기설비학회 2015 조명.전기설비 Vol.29 No.4

소형열병합발전 운영 경제성 분석 시뮬레이션

임용훈,박화춘 한국에너지공학회 2011 한국에너지공학회 학술발표회 Vol.2011 No.4

비선형 시스템의 왜곡 보상을 위한 비선형 적응 프리필터

임용훈,조용수,윤대희,차일환 대한전자공학회 1995 전자공학회논문지-B Vol.b32 No.7

In This Paper, Linearization problem is discussed to reduce distortion of a nonlinear system based on Schetzen's pth-orfer inverse theorem. We propose a nonlinear adaptive prefiltering algorithm which can reduse nonlinear distortion up to pth order by tandemly connecting a pth-order Volterra filter before the nonlinear system under the consideration and by adjusting the filter coefficients adaptively. The feasibility of applying the proposed algorithm to a nonlinear system is conformed via computer simulation by observing significant reduction of total nonlinear distortion for the case of random input and sinusoidal input excitation.

집단에너지 기반 광역에너지 네트워크 운전 분석 시뮬레이션

임용훈,박화춘 한국에너지공학회 2011 한국에너지공학회 학술발표회 Vol.2011 No.4