Step-Up 구조를 갖는 다층박막 초소형 구동소자의 초기변형 최소화에 관한 연구

이희중,강신일,Lee, Hee-Joong,Kang, Shin-Ill 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.11

In the present study, a new anchor design was proposed to minimize the initial deflection of micro multi-layer cantilever beam with step-up structure, which is a key component of thin film micro-mirror array. It is important to minimize the initial deflection, caused by residual stress, because it reduces the performance of the actuation. Theoretical and experimental studies were conducted to examine the cause of the initial bending deflection. It was found that the bending deflection at the anchor of the cantilever beam was the primary source of initial deflection. Various anchor designs were proposed and the initial deflections for each design were calculated by finite element analysis. The analysis results were compared with experiments. To reduce the initial deflection a secondary support was added to the conventional structure. The optimal shapes were obtained by simulation and experiment. It was found from the analysis that the ratio or horizontal and vertical dimensions of secondary support was the governing factor, which affected the initial deflection.

다중 유압 서보 작동기의 force fighting 현상 개선에 관한 연구

이희중(Hee-Joong Lee),최형돈(Hyung-Don Choi),강이석(E-Sok Kang) 한국항공우주연구원 2013 항공우주기술 Vol.12 No.1

항공기의 자세제어를 담당하는 각각의 비행 조종면에 중복안정성 등의 이유로 여러 개의 작동기를 연결하여 사용하고 있다. 다중 작동기들이 동시에 정확하게 같은 위치로 이동하지 않으면 비행조종면에 변형이 발생한다. 그 결과 변형된 조종면이 원래 상태로 복원하려는 힘에 의해 작동기들 간에 force fighting이 발생한다. 게다가 force fighting은 각 장치들의 초기 허용 오차 등에 의해서도 발생한다. 다중 작동기간의 force fighting 현상은 제어정밀도에 영향을 미치고 피로파괴의 원인이 되어 작동기와 비행조종면의 수명을 단축할 수도 있다. 본 논문에서는 두 개의 서보작동기를 사용하는 시스템의 force fighting을 감소하기 위하여 힘되먹임제어를 사용하는 제어기를 설계하였다. In general, multiple hydraulic servo actuators are installed on one control surface of aero-dynamically highly loaded condition aircraft for redundancy management to satisfy flight control safety requirements. If motions of multiple actuators are not synchronized, control surface is deformed from its free stressed state. In result, force fight conditions are generated on each actuator due to restoration reaction force of deformed control surface. In addition, force fight is induced from severe initial rigging tolerance. Force fight condition of multiple actuators affects control accuracies and reduces operational life of actuators and control surface due to fatigue phenomenon. In this study, we designed controller using force feedback to reduce force fight of duplex servo actuation system.

특집 : 한국어문학, 어떻게 교육할 것인가 ; 대학 교양문학 교육의 현실과 대안 -실태 조사 보고와 그 분석-

이희중 ( Hee Joong Lee ) 민족어문학회 2005 어문논집 Vol.51 No.-

지반침하 거동특성 분석을 위한 암반의 부피팽창률에 관한 연구

이희중(Hee-Joong Lee),정용복(Yong-Bok Jung),최성웅(Sung O Choi) 한국암반공학회 2008 터널과지하공간 Vol.18 No.1

초록 지반침하 대상지역 암반의 부피팽창률에 대한 측정방법은 국ㆍ내외적으로 아직까지 규정된 바는 없으며, 그동안 현장에서 화약발파에 의한 암반의 부피증가율로써 부피팽창률을 적용하여 사용하여 왔다. 하지만 이렇게 제시된 부피팽창률은 일정한 기준으로 분류되지 않았을 뿐만 아니라, 각각에서 제시된 값들은 암종에 따라 부피팽창률 범위 차이가 있기 때문에 지반침하 대상지역에 그대로 적용하기에는 다소 무리가 있다. 따라서 본 연구에서는 편마암, 석회암 및 셰일을 대상으로 붕락대에 영향을 미칠 수 있는 파쇄암의 적재 형태에 따른 부피팽창률과 응력에 따른 부피팽창률을 산정하기 위해 파쇄암이 적재된 상태에서 일정한 하중을 가하여 실내실험을 실시하였다. The techniques for measuring the bulking factor of rock mass in subsidence area have never been well known all over the world. The volumetric expansion ratios obtained from blasting operation were the only way of acquiring the bulking factor of rock mass. The bulking factor of rock mass obtained from blasting operation, however, has been seldom classified in a certain criterion. Also the bulking factor of rock mass can be very dependent upon rock types. In order to overcome this limitation obtained from these reasons, the authors studied the experimental bulking factor of rock mass according to the stacking shapes as well as the overburden stresses. Gneiss, limestone and shale were chosen for testing specimens, and each bulking factor has been measured with laboratory test of applying a constant load on the fragmented rock specimens.

만삭 분만에서 임신 주수와 제대동맥혈 pH의 임상적 고찰

이희중 ( Hee Joong Lee ),조현정 ( Hyun Jung Cho ),이윤영 ( Yoon Young Lee ),권동진 ( Dong Jin Kwon ),김사진 ( Sa Jin Kim ),박태철 ( Tae Chul Park ),유영옥 ( Young Ok Lew ),신종철 ( Jong Chul Shin ),김대훈 ( Dae Hoon Kim ) 대한산부인과학회 2004 Obstetrics & Gynecology Science Vol.47 No.7

동적 하중 되먹임 제어를 사용한 직구동 방식 전기기계식 구동장치시스템의 동특성 개선에 관한 연구

이희중(Hee-Joong Lee),강이석(E-Sok Kang),송오섭(Ohseop Song) 한국항공우주학회 2017 韓國航空宇宙學會誌 Vol.45 No.4

발사체의 추력벡터제어를 위한 구동장치시스템에서 관성부하를 갖는 전기기계식 위치서보 시스템의 공진 특성과 유연한 기체구조체 지지부의 구조공진이 결합되어 합성공진이 발생한다. 이렇게 발생한 공진은 발사체의 자세제어시스템에 되먹임되어 자세안정성에 영향을 줄 수 있다. 본 논문에서는 발사체의 추력벡터제어를 위한 직구동 방식의 전기기계식 구동장치의 합성공진을 해석하기 위한 모델을 소개하고 합성공진 현상을 저감하여 구동기의 동특성을 개선하는 동적 하중 되먹임 제어기법의 해석 및 시험 결과를 기술하였다. In the control actuator system of a launch vehicle based on thrust vectoring, the interaction between electro-mechanical position servo and inertial load are combined with the dynamic characteristics of the flexible vehicle support to generate synthetic resonance. This occurred resonance is fed back to the attitude control system and can influence stability of launch vehicle. In this study, we proposed a simulation model to analyze synthetic resonance of electro-mechanical actuation system for thrust vector control and explained the results of simulation and test using dynamic force feedback control which improves dynamic characteristics of servo actuation system by reducing synthetic resonance.

김장생(金長生) - 김집(金集) 계열의 학문 및 정치적 역할

이희중(Lee Hee-Joong) 역사문화연구소 2007 역사문화논총 Vol.- No.3

김소월의 시에서 불의 의미

이희중(Lee Hee-Joong) 한국시학회 2003 한국시학연구 Vol.- No.8

This essay is to analyze ‘fire’ which the writer, Kim So-Wol has used with a unique importance in his works. The word ‘fire’ cannot be said to be a very critical word in his works only to see the frequency of its usage, because it seems as common as any other usage of this word in his quite a few works, but it is shown to be used in a very especial way in his few other works. In particular, we can point out that his works have presented the word ‘fire’ in an outstanding environment in the spaces of a ‘tomb’ or a ‘ridge’. The main critical works being discussed in the essay are some of his works that include the words such as a ‘tomb’, a ‘grass’ and ‘fire’ coordinating in the one work such as Gold Grass(금잔디), Having Lived with my eyes closed(세상 모르고 살았노라) and Cigarette(담배). To be balanced from a viewpoint to construe that all the individual works are one and thorough art structure with a completeness and thus to separate all of each works, it is, to some extent, useful to review comprehensively usage of words, phrases and sentences that the poet has adopted in some of his works. This essay eventually intends to explain all the in dividual works’s interior completeness and also their meaning, but when their meaning varies, I have referred to the same words in the similar sequences or vocabularies of the other works, so that we could search for the way to interpret all the similar phrases and expressions seen across from his various works putting them into one and consistent category. Through the discussion of the essay, let me conclude that the writer, in the works that I have selected for the essay, apparently or implicitly wishes to appose his wish of burning grasses with his desire to recover his ‘nim(님, the lover)’ who is already dead. In that sense, I have offered that there is a way of understanding ‘the grass’ as metonymy of a ‘tomb’ regarding the way of interpreting three respective words-a tomb, a grass and fire-as all in a consistent meaning. So the tomb, in the poem referred to death of ‘nim’, can be reflected to the impossible desire to recover and therefore to eliminate the tomb. This plays a role of activating each of his works by making them become more valuable and more poetic, but it gives a boundary in a sense of presenting the obsession to a dream impossible to make come true as Invoking a Soul(초혼) does.

한국형발사체 추력벡터제어 직구동 방식 전기기계식 구동장치시스템 개발

이희중(Hee-Joong Lee),강이석(E-Sok Kang) 한국항공우주학회 2016 韓國航空宇宙學會誌 Vol.44 No.10

발사체의 피치 및 요 축 자세제어를 위해 엔진의 연소 중 추력의 방향을 변화시키는 추력벡터제어를 많이 사용한다. 발사체의 추력벡터제어를 위한 구동장치로는 중량 대비 동력 효율이 좋은 유압식 구동장치를 보편적으로 사용하여 왔으나 요즘은 고효율의 전기모터 개발과 모터 제어 기법의 발전으로 상대적으로 규모가 작은 발사체의 추력벡터제어에는 전기기계식 구동장치시스템을 적용하는 연구를 많이 수행하고 있다. 본 논문에서는 한국형발사체 3단 엔진의 추력벡터제어를 위해 개발 중인 직구동 방식의 전기-기계식 구동기의 설계 내용 및 시제품 시험결과를 기술하였다. For the pitch and yaw axis attitude control of launch vehicle, thrust vector control which changes the direction of thrust during the engine combustion is commonly used. Hydraulic actuation system has been used generally as a drive system for the thrust vector control of launch vehicles with the advantage of power-to-weight ratio. Nowadays, due to the developments of highly efficient electric motor and motor control techniques, it has done a lot of research to adopt electro-mechanical actuator for thrust vector control of small-sized launch vehicles. This paper describes system design and test results of the prototype of direct drive electro-mechanical actuation system which is being developed for the thrust vector control of 3rd stage engine of KSVL-II

액체엔진 추력벡터제어 구동장치시스템

이희중(Hee-Joong Lee),박문수(Moon-Su Park),민병주(Byeong-Joo Min),노웅래(Woong-Rae Roh),최형돈(Hyung-Don Choi) 한국항공우주학회 2004 韓國航空宇宙學會誌 Vol.32 No.5