식물유에 함침된 절연지의 가속 열화 시험

정종철(Jongchul Jung),이재영(Jae Young Lee),전형준(Hyung Jun Jeon),정현구(Hyeon Gu Jeong),김민규(Min Gyu Kim),윤재훈(Jae Hun Yoon),권정훈(Jung Hun Kwon) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4

전력 변압기의 절연유에 있어서 환경 및 화재에 대한 이슈로 기존 광유보다는 식물성 절연유의 사용이 각광을 받고 있다. 본 논문에서는 식물유에 함침된 절연지의 열화 특성을 연구하였다. 가속 열화 시험을 위하여 권선, 철심, 프레스보드, 절연지 및 식물유가 포함된 열화용 실린더가 질소에 밀봉된 상태로 준비되었고, 고온 항온조에서 8,000 시간까지 열화를 진행하였다. 절연지의 성능 저하를 평가하기 위하여 절연지의 중합도 및 인장강도를 각 샘플링 주기별로 측정하였으며, 절연유에 함유된 퓨란화합물 함량도 함께 분석하였다. 실험을 통하여 중합도 200을 수명점으로 하는 절연지의 기대 수명이 광유에 함침된 경우보다 식물유에 함침된 경우가 훨씬 길다는 것을 보여주었다. Vegetable oils have been increasingly preferred as dielectric fluids in power transformers due to environmental and fire safety issues over conventional mineral oils. This paper presents ageing behaviors of cellulose-based insulation papers impregnated in dielectric vegetable oils. In the experimental setup, sealed steel cylinders filled with nitrogen, containing copper, core, pressboard, insulation paper and dielectric vegetable oil, are aged in temperature-controlled chambers for up to 8,000 hours. The degradation of the insulation paper is investigated at each sampling interval in terms of the tensile strength and the degree of polymerization in paper and the furanic compounds in oil. The results are then compared with those of impregnated in conventional mineral oils. It is demonstrated through the experiment that the expected lifetime of the paper based on the degree of polymerization of 200 in the vegetable oil is much longer than that of in the mineral oil.

비정규지표를 이용한 Well-Conditioned 관측기 설계

정종철(Jongchul Jung),허건수(Kunsoo Huh) 한국생산제조학회 2001 한국공작기계학회 추계학술대회논문집 Vol.2001 No.-

입력 추정을 가진 Kalman 필터를 이용한 타이어 힘 추정

정종철(Jongchul Jung),허건수(Kumsoo Huh) 한국자동차공학회 1999 한국 자동차공학회논문집 Vol.7 No.4

입력관측기의 정량적 성능지표 (Ⅱ) - 정상상태 해석 -

정종철(Jongchul Jung),이범석(Boemsuk Lee),허건수(Kunsoo Huh) 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.10

The closed-loop state and input observer is a pole-placement type observer and estimates unknown state and input variables simultaneously. Pole-placement type observers may have poor performances with respect to modeling error and sensing bias error. The effects of these ill-conditioning factors must be minimized for the robust performance in designing observers. In this paper, the steady-state performance of the closed-loop state and input observer is investigated quantitatively and is represented as the estimation error bounds. The performance indices are selected from these error bounds and are related to the robustness with respect to modeling errors and sensing bias. By considering both transient and steady-state performance, the main performance index is determined as the condition number of the eigenvector matrix based on I.2-norm.<br/>

Convex 최적화 기법을 이용한 비례적분형 칼만필터 설계

정종철(Jongchul Jung),허건수(Kunsoo Huh) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

This paper proposes a design approach of an infinite-horizon robust proportional-integral Kalman filter tor stochastic linear systems under poly topic parametric uncertainties. The proportional-integral estimator has a proportional loop and an integral loop of the estimation error, providing guaranteed minimum estimation error variance. The integral action of the estimator improves robustness against uncertainties such as disturbances and modeling errors. The minimization problem of the estimation error variance is converted into a convex optimization problem subject to linear matrix inequalities, and the proportional and the integral Kalman gains are optimally chosen by solving the problem. The estimation performance of the observer is demonstrated through a numerical example and shows improved robustness against both stochastic and deterministic uncertainties.

적응 롤 안정성 제어를 위한 차량 질량 추정 알고리즘 개발

임성현(Sunghyun Lim),정종철(Jongchul Jung),홍대건(Daegun Hong),한상오(Sangoh Han),허건수(Kunsoo Huh),조희명(Heeyoung Cho),윤재민 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Rollover is one of the significant life threatening factors in SUVs(Sports Utility Vehicles). By applying braking or steering, active roll stability controllers help prevent rollover accidents in SUVs. The performance of these controllers is very sensitive to vehicle inertial parameters such as vehicle mass and mass center height. In this paper, a unified estimation method for vehicle mass is proposed considering available driving conditions. Three estimation algorithms are developed based on longitudinal, lateral or vertical vehicle dynamics, respectively, and are unified. The first algorithm is designed using the longitudinal vehicle dynamics and the recursive least square with the disturbance observer technique is applied for longitudinal traveling case. The second algorithm is designed using the lateral vehicle dynamics, where the longitudinal and lateral velocities are also estimated via Kalman filter. The third algorithm is designed using the vertical vehicle dynamics and the dual recursive least square for estimating vehicle sprung mass. Then three algorithms are integrated to extract the vehicle mass during arbitrary vehicle maneuvering. The performance of the proposed vehicle mass estimation method is demonstrated through simulations.

H-Infinity 기법에 의한 비선형 시스템에서의 강인한 적응 관측기 설계

허건수(Kunsoo Huh),정종철(Jongchul Jung) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

Existing adaptive observers may cause parameter estimate drift due to disturbances even if state estimation errors remain in small. To avoid the drift phenomena in the presence of bounded disturbances, several robust adaptive observers have been introduced addressing bounds in state and parameter estimates. However, it is not easy for these observers to manipulate the size of the bounds with the selection of the observer gain. In order to reduce estimation errors, this paper introduces the H-infinity norm minimization problem in the adaptive observer structure, which minimizes the H-infinity norm between disturbances and estimation errors. The stability condition of the adaptive observer is reformulated as a linear matrix inequality, and the observer gain is optimally chosen by solving the convex optimization problem. The estimation performance is demonstrated through a numerical example.

커패시터의 제조사 보증 수명과 가속열화시험을 통한 실제 수명 비교

이재영(Jae Young Lee),강영민(Young Min Kang),정종철(Jongchul Jung),전형준(Hyung Jun Jeon) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4

SMPS(전원)의 신뢰성을 좌우하는 가장 중요한 부품 중 하나는 커패시터이며, 이는 실제 필드 서비스 데이터를 통해 확인할 수 있다. 그럼에도 불구하고 실제 동작 조건에 부합되지 않는 사양을 가지는 커패시터가 선정되는 경우가 많은데 이는 대부분의 엔지니어가 제한된 개발 기간과 예산으로 인해 제조사의 데이터시트만으로 커패시터를 선정하기 때문이다. 이로 인하여 제조사의 보증 수명과 실제 수명에 큰 차이가 발생한다. 그러므로 SMPS의 신뢰성을 높이기 위하여 보증 수명을 실제 수명으로 변환하는 것이 필요하다. 본 논문은 가속열화시험을 통하여 커패시터가 적용되는 동작 조건에서 실제 수명을 추정하고 신뢰도 예측 규격의 파라미터를 이용하여 보증 수명과 비교하는 방법을 제안한다. 제안된 지침은 설계 단계에서 커패시터를 선정하는 엔지니어에게 유용한 정보가 될 것이다. The one of the most critical parts to reliability of switching mode power supply (SMPS) are capacitors, and actually it can be seen from field service data. Nonetheless, capacitors with inappropriate specifications on their operating conditions have been often selected. It comes from that capacitors are selected by engineers based only on a datasheet by manufacturers due to the limited design period and budgets. It makes the difference between warranty lifetime and actual lifetime. Thus, it needs to convert warranty lifetime to actual lifetime for improving reliability of SMPS. This paper suggests a way to estimate actual lifetime on its applied operating conditions through accelerated degradation test and compare with warranty lifetime using parameters from reliability prediction standards. The suggested guidance can be useful information in selecting capacitors on a design phase to engineers.

대학안전관리 법제화 연구

김경회 ( Kim Kyunghwoi ),강태훈 ( Kang Taehoon ),한종극 ( Han Jongkeuk ),정종철 ( Jung Jongchul ) 인하대학교 교육연구소 2020 교육문화연구 Vol.26 No.4

본 연구는 대학의 종합적 안전관리 체계 구축에 필요한 법률 제정 방향을 논구하고 있다. 대학의 안전을 규율하는 법령분석을 통해서 국가나 대학 차원에서 종합적이고 체계적 안전관리에 요구되는 법규가 미비하다는 점을 밝히고 있다. 대학의 안전관리 실태조사를 실시하여 안전관리 전담부서가 설치된 대학은 14%에 불과하고, 대학 자체적으로 안전관리규정을 갖추고 있는 대학도 15%에 지나지 않으며, 안전관리계획을 수립하고 있는 대학도 58%로서 전반적으로 조직, 인력, 규정 등 제도적 기반이 미흡함을 지적하고 있다. 20대 국회에 발의된 대학안전관리의 근거를 마련하는 법률안 내용은 선언적인 규정이 많아서 실효성에 한계점을 지닌다. 이에 본 연구는 고등교육법을 개정하여 종합적인 대학안전계획의 수립과 시행 체제 마련이 요구됨을 밝히고 있다. 아울러 대학안전사고 공제 사업 기관을 지정하여 국가의 공적 보상 범위를 넓힐 것을 제안한다. This study addresses the direction of legislation required to establish a comprehensive safety management system for higher education institutes. First, through an analysis of the college's safety regulations and laws, it was revealed that the relevant laws and regulations required for comprehensive and systematic safety management were insufficient. A survey on the status of safety management for higher education institutes found that only 14% of universities had safety management departments, only 15% had their own safety management regulations, and only 58% developed their own safety management plans. Overall, it was found that institutional foundations for college safety such as organization, manpower, and regulations were not well established. In response, this study suggests revising the Higher Education Act to establish a comprehensive college safety plan and implementation system. It proposes to designate a college safety and insurance institution to expand the scope of the public compensation.

LMI를 이용한 Well-Conditioned 관측기 설계

허건수,정종철 한국공작기계학회 2003 한국공작기계학회 춘계학술대회논문집 Vol.2003 No.-

The well-conditioned observer in a stochastic system is designed so that the observer is less sensitive to the ill-conditioning factors in transient and steady-state observer performance. These factors include not only deterministic issues such as unknown initial estimation error, round-off error, modeling error and sensing bias, but also stochastic issues such as disturbance and sensor noise. In deterministic perspectives, a small value in the L₂ norm condition number of the observer eigenvector matrix guarantees robust estimation performance to the deterministic issues and its upper bound can be minimized by reducing the observer gain and increasing the decay rate. Both deterministic and stochastic issues are considered as a weighted sum with a LMI (Linear Matrix Inequality) formulation. The gain in the well-conditioned observer is optimally chosen by the optimization technique. Simulation examples are given to evaluate the estimation performance of the proposed observer.