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이민기,김태성,박근우,Lee, Min-Ki,Kim, Tae-Sung,Park, Kun-Woo 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.11
This research develops a low-cost and high accuracy kinematic calibration method based on the following principles: 1) the platform locations are accurately measured by a constrained movement to inspect a calibration target; 2) the constrained movement is chosen to guarantee the parameter observability; 3) the mechanical fixture to constrain the movement and the sensor to check the constrained movement are implemented by low-cost and high-accuracy devices; 4) the calibration is easily done at an industrial environment. The kinematic parameters calibrated with respect to a single plane aren't influenced due to the misalignment of the plane. A parameter observability is successfully obtained even through one planar constraint, which guarantees that all kinematic parameters are estimated by minimizing the cost function.
G.729 코덱의 패킷 손실 영향 모델을 이용한 비 침입적 음질 예측 기법
이민기,강홍구,Lee, Min-Ki,Kang, Hong-Goo 한국음향학회 2013 韓國音響學會誌 Vol.32 No.2
본 논문은 패킷 손실의 영향을 이용한 비 침입적 음질 평가 방법을 제안한다. 패킷 손실은 패킷 기반의 통신 시스템에서 음질을 저하시키는 주된 요소이며 그 영향은 코덱에 내장된 패킷 손실 은닉 알고리듬에 의해 결정된다. 패킷 손실 영향을 반영한 음질평가 시스템을 위해 VoIP 에서 협대역 코덱으로 사용되는 코덱 중 하나인 G.729를 선택하였으며, 음성 특징에 따른 패킷 손실 영향을 구분하기 위해서 G.729 코덱의 음성 파라미터를 이용한 한 음성 특성 분류기를 설계하였다. 이후, 각각의 패킷 특성에 따른 음질 저하의 정도를 수치화하기 위해 원 PESQ-LQ점수와 상관계수를 최대화하는 음질 저하 가중치를 반복적으로 구하였으며, 최종 음질 저하는 가중합으로 구하였다. 그 결과 제안한 모델과 PESQ-LQ의 상관계수는 칩입 모델 에서는 0.8950를, 비 침입 모델 에서는 0.8911의 결과를 나타내었다. This paper proposes a non-intrusive speech quality estimation method considering the effects of packet loss to perceptual quality. Packet loss is a major reason of quality degradation in a packet based speech communications network, whose effects are different according to the input speech characteristics or the performance of the embedded packet loss concealment (PLC) algorithm. For the quality estimation system that involves packet loss effects, we first observe the packet loss of G.729 codec which is one of narrowband codec in VoIP system. In order to quantify the lost packet affects, we design a classification algorithm only using speech parameters of G.729 decoder. Then, the degradation values of each class are iteratively selected that maximizes the correlation with the degradation PESQ-LQ scores, and total quality degradation is modeled by the weighted sum. From analyzing the correlation measures, we obtained correlation values of 0.8950 for the intrusive model and 0.8911 for the non-intrusive method.
이민기,박근우,Lee, Min-Ki,Park, Kun-Woo 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.1
The determination of the direct kinematics of the parallel mechanism is a difficult problem but has to be solved for any practical use. This paper presents the efficient formulation of the direct kinematics for double parallel robot arm. The robot arm consists of two parallel mechanism, which generate positional and orientational motions, respectively. These motions are decoupled by a passive central axis which is composed of four revolute joints and one prismatic joint. For a set of given lengths of linear actuators, the direct kinematics will find the joint displacements of th central axis from geometric constraints in each parallel mechanism. Then the joint displacements will be converted into the position and the orientation of the end effector of the robot arm. The proposed formulation is decoupled and compacted so that it will be implemented as a real-time direct kinematics. With the proposed formulation, we analyze the motion of the double parallel robot and show its characteristics. Specially, we investigate the workspace in terms of positional space as well as orientational space.
Gantry Type 공작기계의 CROSS RAIL 처짐량 측정 및 분석
이민기(Min Ki Lee),박재범(Jae Beom Park),김남성(Nam Sung Kim),민들레(Deul Le Min),이응석(Eung Suk Lee) 한국생산제조학회 2010 한국공작기계학회 추계학술대회논문집 Vol.2010 No.-
This study of purpose is to predict and to compensate displacement of Cross Rail of Gantry type when Spindle Head is moving on Y-axis anywhere. For composition of experiment is Mahr probe, Mahr Millitron 1240, A/D converter. As moving 500kg of mass block, measure displacement and compare with analytical result which load is acting on Y-axis at certain location so we show method of compensation and it is possible and efficient one of others. The analysis is carried out by FEA simulation using ANSYS also we induce equation.
축차 2점법을 이용한 회전체의 진원도 프로파일 측정에 관한 연구
이민기(Min Ki Lee),이응석(Eung Suk Lee) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.8
본 논문은 회전체의 진원도 및 흔들림 정밀도 측정에 관한 연구이다. 일반적으로 가공물 진원도 측정은 정밀한 회전테이블 또는 기준 원형 디스크를 필요로 하여, 고가의 비용이 소요된다. 축차2점법은 2개의 변위센서를 사용하여 직선가이드 등에서진직도 측정을 위하여 사용되었으며, 본 연구에서는 이 방법을 회전체에 적용하였다. 한 개의 디스크를 이용하여 측정된 회전체 변위 측정값에서 장치의 회전시 흔들림 오차를 제거하여 회전체의 순수한 진원도 프로파일을 측정하였다. 본 연구는 정밀한 기준 디스크 (Artifact)를 사용하지 않고 원형 가공물의 진원도 프로파일 측정에 유용할 것이다. In this paper, we present the roundness profile and run-out error measurement for a rotating shaft. The devices for measuring the roundness require a precision rotation table which is used as a reference to obtain the circular profile. Therefore, the roundness measuring system is expensive and requires precision manufacturing. The two-point method for succession measurement has been used to obtain a linear profile or used in straightness measurement using two displacement measuring devices. In this paper, the method is used for measuring the circular profile of a rotating shaft. A method to remove the vibration of the shaft, i.e., the run-out, is used, and the original circular profile is obtained from the measured raw data that excludes the run-out error of the rotating shaft. This method will be useful for obtaining the precise circular profile without using a precision reference circular artifact.
초저온·고진공 환경에서의 Micro Alignment Telescope(MAT)를 이용한 초전도 가속관의 정밀정렬측정에 관한 연구
이민기(Min Ki Lee),김영권(Young Kwon Kim),조용우(Yong Woo Jo),최종완(Jong Wan Choi),김우강(Woo Kang Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
RAON is a heavy ion accelerator for the Rare Isotope Science Project (RISP) at the Institute for Basic Science (IBS) in Korea. The accelerator complex consists of three superconducting linear accelerators, called SCL1, SCL2, SCL3. A linear accelerator, SCL1, utilizes superconducting Quarter Wave Resonators (QWRs) and Half Wave Resonators (HWRs). A QWR cavity was installed in a cryostat. After cooling down to a cryogenic temperature in a ultra high vacuum, we measured position misalignments of the QWR cavity due to cooling down. In this paper, a precise position measurement and misalignment compensation method are presented for the QWR cavities.
이민기 ( Min-ki Lee ),김헌웅 ( Heon-woong Kim ),이선혜 ( Seon-hye Lee ),게릴라아사메누 ( Gelila Asamenew ),이수지 ( Suji Lee ),최용민 ( Yongmin Choi ),박진주 ( Jin Ju Park ),이상훈 ( Sang-hoon Lee ),김정봉 ( Jung-bong Kim ) 한국환경농학회 2019 한국환경농학회 학술대회집 Vol.2019 No.-
Capillary wormwood (Artemisia capillaris Thunberg) and crown daisy (Chrysanthemum coronarium L.) belonging to Family Asteraceae have been regarded as traditional medicinal herbs for preventive effects against chronic diseases including vascular disease, diabetes mellitus, and obesity. These plants are known for major resource of diverse caffeoylquinic acid (CQA) derivatives and flavonoid glycosides. Thus, objective of this study was to observe effects on high thermal and pressure processing to their CQA derivatives from capillary wormwood and crown daisy. A total of twenty-six hydroxycinnamoylquinic acid (HCQA) derivatives including p-coumaroylquinic acids (21), CQAs (3), and feruloylquinic acids (2) were separated and identified using UPLC-DAD-QToF/MS. Among them, a total twelve of HCQA derivatives was newly reported. Capillary wormwood and crown daisy were presented great majority of 5-O-caffeoylquinic acid (chlorogenic acid) and 3,5-di-O-caffeoylquinic acid (isochlorogenic acid A). In addition, 3,5-di-O-caffeoyl-4-O-succinylquinic acid was predominant compound in crown daisy. The total contents of HCQA derivatives were tended to decrease slightly during high thermal and pressure processing. Especially, the CQA derivatives which were esterified at 5- position of quinic acid moiety including chlorogenic acid and isochlorogenic acid A were tended to convert 3- and 4- position of CQA derivatives during processing. Therefore, proper high thermal and pressure processing is possible to enhance active ingredients. Furthermore, it can give valuable information for future research of functional foods and drugs.