Mechanical verification logic and first test results for the Euclid spacecraft

Calvi, Adriano,Bastia, Patrizia,Suarez, Manuel Perez,Neumann, Philipp,Carbonell, Albert Techno-Press 2020 Advances in aircraft and spacecraft science Vol.7 No.3

Euclid is an optical/near-infrared survey mission of the European Space Agency (ESA) to investigate the nature of dark energy, dark matter and gravity by observing the geometry of the Universe and the formation of structures over cosmological timescales. The Euclid spacecraft mechanical architecture comprises the Payload Module (PLM) and the Service Module (SVM) connected by an interface structure designed to maximize thermal and mechanical decoupling. This paper shortly illustrates the mechanical system of the spacecraft and the mechanical verification philosophy which is based on the Structural and Thermal Model (STM), built at flight standard for structure and thermal qualification and the Proto Flight Model (PFM), used to complete the qualification programme. It will be submitted to a proto-flight test approach and it will be suitable for launch and flight operations. Within the overall verification approach crucial mechanical tests have been successfully performed (2018) on the SVM platform and on the sunshield (SSH) subsystem: the SVM platform static test, the SSH structure modal survey test and the SSH sine vibration qualification test. The paper reports the objectives and the main results of these tests.

An exact solution for mechanical behavior of BFRP Nano-thin films embedded in NEMS

Altabey, Wael A. Techno-Press 2017 Advances in nano research Vol.5 No.4

Knowledge of thin films mechanical properties is strongly associated to the reliability and the performances of Nano Electro Mechanical Systems (NEMS). In the literature, there are several methods for micro materials characterization. Bulge test is an established nondestructive technique for studying the mechanical properties of thin films. This study improve the performances of NEMS by investigating the mechanical behavior of Nano rectangular thin film (NRTF) made of new material embedded in Nano Electro Mechanical Systems (NEMS) by developing the bulge test technique. The NRTF built from adhesively-bonded layers of basalt fiber reinforced polymer (BFRP) laminate composite materials in Nano size at room temperature and were used for plane-strain bulging. The NRTF is first pre-stressed to ensure that is no initial deflection before applied the loads on NRTF and then clamped between two plates. A differential pressure is applying to a deformation of the laminated composite NRTF. This makes the plane-strain bulge test idea for studying the mechanical behavior of laminated composite NRTF in both the elastic and plastic regimes. An exact solution of governing equations for symmetric cross-ply BFRP laminated composite NRTF was established with taking in-to account the effect of the residual strength from pre-stressed loading. The stress-strain relationship of the BFRP laminated composite NRTF was determined by hydraulic bulging test. The NRTF thickness gradation in different points of hemisphere formed in bulge test was analysed.

비파괴 계장화 압입시험을 이용한 저항 점용접부 물성 평가

최철영,김준기,홍재근,염종택,박영도,Choi, Chul-Young,Kim, Jun-Ki,Hong, Jae-Keun,Yeom, Jong-Taek,Park, Yeong-Do 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.1

Nondestructive instrumented indentation test is the method to evaluate the mechanical properties by analyzing load - displacement curve when forming indentation on the surface of the specimen within hundreds of micro-indentation depth. Resistance spot welded samples are known to difficult to measure the local mechanical properties due to the combination of microstructural changes with heat input. Particularly, more difficulties arise to evaluate local mechanical properties of resistance spot welds because of having narrow HAZ, as well as dramatic changed in microstructure and hardness properties across the welds. In this study, evaluation of the local mechanical properties of resistance spot welds was carried out using the characterization of Instrumented Indentation testing. Resistance spot welding were performed for 590MPa DP (Dual Phase) steels and 780MPa TRIP (Transformation Induced Plasticity) steels following ISO 18278-2 condition. Mechanical properties of base metal using tensile test and Instrumented Indentation test showed similar results. Also it is possible to measure local mechanical properties of the center of fusion zone, edge of fusion zone, HAZ and base metal regions by using instrumented indentation test. Therefore, measurement of local mechanical properties using instrumented indentation test is efficient, reliable and relatively simple technique to evaluate the tensile strength, yield strength and hardening exponent.

Mechanical Strength Evaluation of A53B Carbon Steel Subjected to High Temperature Hydrogen Attack

( Maan Won Kim ),( Joon Won Lee ),( Kee Bong Yoon ),( Jai Hak Park ) 한국안전학회(구-한국산업안전학회) 2007 International Journal of Safety Vol.6 No.2

In this study mechanical strength of A53B carbon steel was analyzed using several types of test specimens directly machined from oil recycling pipe experienced a failure due to hydrogen attack in chemical plants. High temperature hydrogen attack (HTHA) is the damage process of grain boundary facets due to a chemical reaction of carbides with hydrogen, thus forming cavities with high pressure methane gas. Driven by the methane gas pressure, the cavities grow on grain boundaries forming intergranular micro cracks. Microscopic optical examination, tensile test, Charpy impact test, hardness measurement, and small punch (SP) test were performed. Carbon content of the hydrogen attacked specimens was dramatically reduced compared with that of standard specification of A53B. Traces of decarburization and micro-cracks were observed by optical and scanning electron microscopy. Charpy impact energy in hydrogen attacked part of the pipe exhibited very low values due to the decarburization and micro fissure formation by HTHA, on the other hand, data tested from the sound part of the pipe showed high and scattered impact energy. Maximum reaction forces and ductility in SP test were decreased at hydrogen attacked part of the pipe compared with sound part of the pipe. Finite element analyses for SP test were performed to estimate tensile properties for untested part of the pipe in tensile test. And fracture toughness was calculated using an equivalent strain concept with SP test and finite element analysis results.

Mechanical Strength Evaluation of A53B Carbon Steel Subjected to High Temperature Hydrogen Attack

Kim, Maan-Won,Lee, Joon-Won,Yoon, Kee-Bong,Park, Jai-Hak The Korean Society of Safety 2007 International Journal of Safety Vol.6 No.2

In this study mechanical strength of A53B carbon steel was analyzed using several types of test specimens directly machined from oil recycling pipe experienced a failure due to hydrogen attack in chemical plants. High temperature hydrogen attack (HTHA) is the damage process of grain boundary facets due to a chemical reaction of carbides with hydrogen, thus forming cavities with high pressure methane gas. Driven by the methane gas pressure, the cavities grow on grain boundaries forming intergranular micro cracks. Microscopic optical examination, tensile test, Charpy impact test, hardness measurement, and small punch (SP) test were performed. Carbon content of the hydrogen attacked specimens was dramatically reduced compared with that of standard specification of A53B. Traces of decarburization and micro-cracks were observed by optical and scanning electron microscopy. Charpy impact energy in hydrogen attacked part of the pipe exhibited very low values due to the decarburization and micro fissure formation by HTHA, on the other hand, data tested from the sound part of the pipe showed high and scattered impact energy. Maximum reaction forces and ductility in SP test were decreased at hydrogen attacked part of the pipe compared with sound part of the pipe. Finite element analyses for SP test were performed to estimate tensile properties for untested part of the pipe in tensile test. And fracture toughness was calculated using an equivalent strain concept with SP test and finite element analysis results.

검사 상황 차이에 따른 진화 기작 개념의 응답 유형 분석

이혜림,차희영,김성하,하민수 韓國生物敎育學會 2010 생물교육 Vol.38 No.3

The purpose of this study was to analyze students' concepts in different test conditions about mechanisms of evolution. The tests were carried out in the low-and high-stakes test condition intended the 28 ninth graders. For this study, a questionnaire to investigate students' conception about evolutionary mechanism were selected and modified to paralleled test forms. MATE test to measure conceptual acceptance for evolution theory was applied. The research subjects are divided into two groups randomly, paralleled tests were administered to both groups. Based on the consistency and scores of answers, 16 interviewees were selected. The results of analysis of the students conceptions about evolutionary mechanism showed that the test score performed in high-stakes condition was higher than that performed in low-stakes condition. The patterns of answers by interviewees were divided into four types: scientific theorists, misconceptionists, conceptional confusers, and pragmatist. First three types were not related with test condition; however, the pragmatists answered with the same pattern as scientific theorists in high-stake test condition but they did differently at the lowstake test condition. These result is meaningful as that test condition might influence answers responded by students about evolutionary mechanism. Therefore, test conditions have to be considered as one of the factors when tests will be administered for students to identify students' real conceptions about evolution.

정의적 특성 검사 자료 분석을 위한 문항반응모형 탐색: 일반화등급전개모형과 일반화부분점수모형의 적용을 중심으로

강태훈,김동일 한국교육평가학회 2010 교육평가연구 Vol.23 No.1

This study highlights the theoretical and practical differences between the generalized graded unfolding model and the generalized partial credit model in analyzing affective testing data. The latter is one of traditional polytomous item response models that have widely used for the purpose of data analysis of affective testing as well as cognitive testing. Although it could be usually assumed the examinees' responses to cognitive testing items follow cumulative mechanisms, unfolding mechanisms could excel in the responses to affective testing items. At that moment, an alternative model implying the concept of unfolding would be required. This study introduced various polytomous item response models and applied them to the actual data of internet addiction diagnosis scale. To compare the performances of such models, the model selection indices such as AIC, BIC and DIC were calculated. Also, assessing the item fit was carried out to check the appropriateness of each model for the given data. Finally, the meaning of applying an unfolding item response model to affective testing data was further discussed. 본 연구에서는 정의적 특성 검사 자료를 분석하기 위하여 일반화등급전개모형과 일반화부분점수모형을 적용하고 결과를 제시하였다. 일반화부분점수모형과 같은 전통적 다분문항반응모형은 지능이나 학업성취도 등의 인지적 특성과 태도와 같은 정의적 특성을 재는 검사 결과 분석에 있어서도 널리 사용되었다. 인지 검사 문항에 대한 피험자의 응답은 흔히 누적 기제를 따르는 것으로 가정될 수 있다. 하지만 태도 및 성격 등과 같은 정의적 특성 관련 검사에 있어서는 검사 문항에 대한 피험자의 응답이 누적 기제가 아닌 전개 기제를 따르는 경우가 있기 때문에 일반화등급전개모형과 같은 대안적 문항반응모형을 고려할 필요가 있다. 본 연구에서는 이들 모형에 대한 이론적 소개와 함께 실제 인터넷 중독 진단 검사 결과를 바탕으로 아래와 같은 분석이 실시되었다. 우선 모형 각각에 대하여 AIC, BIC, 그리고 DIC 등의 통계적 모형 선택 지수를 계산하여 통계적으로 보다 적절한 문항반응모형이 무엇인지 살펴보았고, 추가로 문항별 통계적 적합도 검증을 실시하여 문항 수준에서의 모형 적합도를 검토하였다. 마지막으로 전개 기제 문항반응모형의 적용 의의를 논의하였다.

진로선택에서 나타난 의과대학생의 자아방어기제

정한용,한선호,최의정,김동욱 大韓神經精神醫學會 1999 신경정신의학 Vol.38 No.6

연구목적: 객관적인 질문지 형태의 이화방어기제검사를 사용하여, 의과대학생의 향후 전문과목 선택에 있어 크게 내, 외과 계열을 선택하는 사람들 사이의 자아방어기제상의 차이가 있는 지를 살펴봄으로써, 특정과를 선호하는 데에 따른 학생들의 공통적인 성격 특성이나 적응방식이 과별로 차이가 있는가를 살펴보고자 하였다. 방 법: 순천향 의과대학에 재학중인 본과 4학년을 대상으로 이화방어기제검사를 이용하여 내과계열과 외과계열을 선택한 학생들 사이의 방어기제를 비교하였다. 결 과: 내과와 외과를 선택한 학생 집단간의 방어기제들의 평균점수와 성숙도에 따라 나눈 4개의 방어기제군의 평균점수에는 유의한 차이가 없었다. 그러나 주된 방어기제를 사용하는 빈도를 비교한 결과 미숙한 방어기제에서 수동-공격(passive-aggression)과 신경증적 방어기제에서 허세(show-off)는 외과군이 내과군에 비해 그 빈도가 유의하게 높았던 반면, 성숙한 방어기제에서는 유우머(humor)를 주된 방어기제로 사용하는 학생수의 빈도가 내과를 선택한 학생들이 외과를 선택한 학생들보다 유의하게 높았다. 결 론: 주된 방어기제의 빈도 차를 분석해 본 결과 학생 집단간의 성격 상 유의한 차이는 보이지 않았다. 그러나 내과를 선택한 학생들에서 외과를 선택한 학생들보다 성숙한 방어기제에서의 유우머(humor)를 주된 방어기제로 사용한 학생들의 빈도가 높아 갈등이나 불안, 고통의 상황에서 유우머를 통하여 이런 상황을 견디는 힘을 얻게되고, 이러한 개인의 경우 강한 자아 강도를 지니고 있을 가능성이 높게 보일 수 있는 학생들이 많았다. 반면, 외과계열을 선택한 학생들은 미숙한 방어기전에서 다른 사람에 대한 공격적인 감정을 직접적으로 표현하지 않고, 간접적으로 수동적 저항으로 표현함으로써 자신의 공격적인 감정을 처리하는 수동-공격(passive-aggression)에서 높은 빈도를 보였다. 또한, 신경증적 방어기제에서 자신의 능력에 비해서 과분한 행동 목표를 결정하고 이를 과시하고 특히 자신의 행동이 타인에게 어떻게 평가받을 지에 대해 상당히 민감한 타인 지향적 성향을 지니는 허세(show-off)를 주된 방어기제로 사용한 학생들이 많았다. 이러한 결과는 전공에 따른 공통 성격특성과 적응방식의 차이를 밝혀냄으로써 그 과의 특성에 따른 적성을 알아내는데 도움이 될 것 같다. Objectives: To determine differences of common personality profiles and coping mechanisms of medical students who prefer specific specialties(medicine and surgery), the authors evaluated the defense mechanisms of the medical students by using Ewha Defense Mechanisms Test. Methods: The authors compared the defense mechanisms between two groups(medicine selection group and surgery selection group) who are in the senior year of the Soonchunhyang University School of Medicine. Results: There were no significant differences in mean scores of the each defense mechanism and 4 groups of defense mechanisms divided by maturity level between the groups of students who selected medicine and surgery. But, frequency of major defense mechanisms were as follows: For the surgery selection group, the passive-aggression in the Immature defense mechanism and show-off in the Neurotic defense mechanism were significantly higher than in the medicine selection group. Contrarily, in the medicine selection group, humor in the mature defense mechanism as the major defense mechanism was significantly higher than in the surgery selection group. Conclusion: After analysis of the difference of frequency of major defense mechanisms between the two groups, there were no significant differences between the two groups in personality. However, the students of the medicine selection group used humor of the mature defense mechanism as a major defense mechanism in higher frequency than the surgery selection group. In situations of complications, anxiety and suffering, the use of the humor defense mechanism gave the students strength to endure these situations. Among these students, there is a high probability that many of them possess strong ego strength. Contrarily, the students of the surgery selection group did not express aggression directly, rather, they expressed these feelings indirectly through passive opposition. There was a high frequency of passive-aggression defense mechanism in dealing with feelings of aggression. Also, in the neurotic defense mechanism, compared to ability, excessive goals were set as was the resulting behavior. Especially, behavior was extremely sensitive to how others would evaluate those actions resulting in using show-off mechanism as a major defense mechanism in higher frequency by the surgery selection group. The results seem to be useful in understanding the student`s optimal character for specific specialities that were selected by evaluating the differences of the common characteristics and coping mechanisms of each specialty group.

전기-기계식 점화안전장치 자연 노화 특성 연구

안명근(Myunggeun Ahn),김동성(Dong-seong Kim),장승교(Seung-gyo Jang) 한국추진공학회 2023 한국추진공학회 학술대회논문집 Vol.2023 No.11

2002년~2006년에 제작되고 약 20년 자연 노화된 전기-기계식 점화안전장치를 이용하여 노화 특성 평가를 통해 수명연장과 이에 따른 성능분석을 수행하였다. 미군사규격을 기반으로 환경시험, 밀폐용기시험 및 전자파 간섭시험을 수행하였으며, 시제 분해 후 내부 부품 노화 및 부식도 분석을 수행하였다. 밀폐용기 시험을 통한 연소성능시험 결과에서 대상 시제의 90%가 성능 적합 판정을 받았으며, 전자파 간섭을 통한 우발점화 평가에서도 적합성을 인증받았다. 또한 부품 분해 후 수행된 분석에서는 수분침투 흔적이 없었으며, 모든 점화안전장치가 정상적으로 작동하였다. 그러나 추가적인 가속노화를 위한 30일 고온저장 시험 중 일부 시제의 부품 결함이 발견되었다. 따라서 본 전기-기계식 점화안전장치는 약 20년의 자연 노화에서는 결함이 발견되지 않았으나 수명연장을 위한 추가적인 가속노화에서는 미미한 결함이 발견되어 자연 노화 수명은 약 20년 정도로 예측되었다. 추가적인 가속노화시험에서 미미한 결함은 추가로 발견되었으나 장전 및 점화 성능에는 영향이 없었으므로 3년의 수명연장이 가능한 것으로 판단하였다. This investigation undertakes a comprehensive analysis of the life extension and performance attributes of Electro-Mechanical Arm Fire Device(AFD) systems, manufactured between 2002 and 2006, that have undergone a natural aging process spanning approximately two decades. Aging characteristics were meticulously evaluated through a series of environmental tests, Closed Boom Tests(CBT), and Electromagnetic Compatibility(EMC) tests, all conducted in adherence to US military standards. Following disassembly, a thorough examination of internal components for aging and corrosion was performed. The combustion performance test, particularly the CBT, indicated that 90% of the targeted devices demonstrated passable performance. The system achieved certification for compliance in accidental ignition scenarios during EMC testing. Upon post-disassembly analysis, an absence of evidence pertaining to moisture penetration was observed, and all AFDs exhibited normal operational functionality. Nevertheless, a subset of AFDs manifested component defects during a 30-day high-temperature storage test, specifically designed for accelerated aging simulations. While the Electro-Mechanical AFD showed no defects after its natural aging over two decades, minor discrepancies surfaced during additional accelerated aging tests. These discrepancies did not compromise arming and ignition performance, affirming the feasibility of extending the life extension by an additional three years.

블레이드 제어용 전기식 작동기 환경시험 계획

김현기 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.6

Aircraft operate under various aircraft operational scenarios depending on the weather or aircraft operational conditions. In particular, an aircraft is exposed to various environmental conditions during flight, such as dusty, humid, saline, and low temperature/pressure environments and rain or snowfall. In addition, the aircraft modules are subjected to vibration or impact during aircraft take-off or landing. Hence, the aircraft's safety against various environmental conditions during aircraft operation must be verified through environmental tests. Notably, this research reviewed the environmental conditions affecting the rotor-blade-controlling electro-mechanical actuator (under development in South Korea) of an electric vertical take-off and landing (eVTOL) personal air vehicle (PAV) and established an environmental test plan for this electro-mechanical actuator. In particular, this research reviewed the environmental test items and procedures stipulated in the aircraft development's mainly used environmental test standards: DO-160G, IEC 60068, MIL-STD-810, and KS-W 0811 and identified the performance principles for environmental tests recommended in these standards. Finally, the environmental test plan for the rotor-blade-controlling electro-mechanical actuator of an eVTOL PAV was established based on the DO-160G after reflecting on the environmental test requirements recommended by the above-mentioned standards. 항공기는 날씨 혹은 운행 상황에 따라 다양한 운용 시나리오가 존재한다. 비행 과정에서 먼지나 습도, 염분, 강우 혹은 강설, 저온의 환경과 낮은 압력 등 다양한 환경조건에 노출될 수 있으며, 이륙 또는 착륙 시에는 부품이나 모듈에 진동이나 충격이 발생할 수 있다. 이런 이유로, 항공기는 환경시험을 통해 운용 중에 발생할 수 있는 다양한 환경조건에 대한 안전성이 검증되어야 한다. 본 연구에서는 전기 수직 이착륙 개인항공기(eVTOL PAV) 적용을 목표로 국내에서 개발 진행 중인 블레이드 제어용 전기식 작동기에 요구되는 환경조건을 검토하고, 그에 대한 환경시험 수행계획을 수립하였다. 이를 위해 항공기 개발 시 환경시험 기준으로 주로 적용되고 있는 DO-160G, IEC 60068, MIL-STD-810 그리고 KS-W 0811에서 규정하고 있는 환경시험 종류와 절차를 조사하고, 각 규격에서 권고하고 있는 환경시험에 대한 수행원칙을 파악하였다. 이를 종합하여 DO-160G를 기반으로 하고, MIL-STD-810, IEC 60068와 KS-W 0811에서 권고하는 환경시험 제반사항을 반영하여 eVTOL 항공기의 블레이드 제어용 전기식 작동기에 대한 환경시험 계획을 수립하였다.