• 한국주거학회논문집
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• 제21권6호
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• pp.71-80
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• 2010

The purpose of this study is to classify defects of the residential building by analyzing the defect specified by prequalification of residential building reconstruction and to suggest the solution of the problem which can be arisen during each stage of plan, construction and maintenance. By sorting the main defects which is specified by pre-qualification of residential building reconstruction for three years from August 2006 to August 2009 into 4 catagories and analyzing the cause of the defects, we draw the way of maintenance to prevent the defects and make pleasant residential environment. The reason for the frequent defects from residential building is mainly deterioration. It occured on the finishing more than on the structure, which means that residents can find defects easier on the finishing than the structure and clear the demand for repair. The result of analyzing of pre-qualification of residential building reconstruction is that the defects mostly caused small, masonry constructed and lower apartment. The apartment which is not into legal right for maintenance naturally have more defects than the others. In conclusion, it is necessary to establish a law of obligation duty of the maintenance of small apartment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2603-2605
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• 2005

This paper describes an experience on the equipment qualification of CRCS(control rod control system) that has been developed for nuclear power plants. A very high level criteria should be satisfied for the equipment to be used for nuclear power plants. We have developed a CRCS that is aimed to be applied to commercial plants. This system adopts a duplex system structure that is based on the state-of-the-art digital technology so that it has higher reliability than the existing systems. The CRCS has been tested at a licensed testing organization and finally qualified. In this paper, the procedures and some trial-and-errors we have been through in the qualification process are explained. It is expected that our experience will be a helpful tips to the industry that are developing various systems for safety-critical plants.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.198-200
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• 2017

보조동력장치(Auxiliary Power Unit: APU)는 항공기에 장착되어 주엔진의 지상 및 공중 시동을 위한 에너지를 공급하고 항공기의 비상 및 보조 전원을 공급하는 역할을 하는 소형 가스터빈엔진이다. 항공기용 APU는 구조가 간단하고 소형이지만 유인 항공기에 장착되기 때문에 높은 신뢰성이 요구되므로 인증 절차를 통하여 그 신뢰성을 입증하여야 한다. 한국항공우주연구원은 2007년부터 2012년까지 한화 테크윈과 함께 축적된 국내 연구개발 역량 및 경험을 바탕으로 헬리콥터용 APU의 설계/해석, 제작 및 조립, 개발시험 및 인증시험을 평가를 성공적으로 완료하였다. 본 논문에서는 헬리콥터용 보조동력장치의 개발 및 인증 과정에 대하여 정리하였다.

• Advances in aircraft and spacecraft science
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• 제7권3호
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• pp.251-269
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• 2020

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.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.1142-1153
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• 2019

This paper presents the effect of fusion procedure on the fusion performance of the thermal butt fusion in the safety class III buried HDPE piping per various tests performed, including high speed tensile impact, free bend, blunt notched tensile, notched creep, and PENT tests. The suitability of fusion joints and qualification procedures was evaluated by comparing test results from the base material and buttfusion joints. From the notched tensile test result, it was found that the fused joints have much lower toughness than the base material. It was also identified that the notched tensile test is more desirable than the high speed tensile impact and free bend tests presented in the ASME Code Case N-755-3 as a fusion qualification test method. In addition, with regard to the single low-pressure fusion joint performances, the procedure given by the ISO 21307 was determined to be better that the one specified in the Code Case N-755-3.

• Advances in aircraft and spacecraft science
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• 제5권2호
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• 융합보안논문지
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• 제13권5호
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• pp.117-127
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• 2013

한국의 민간경비 산업은 발전하고 있지만 영세한 업체들의 난립으로 인해 결국 저가입찰을 할 수 밖에 없다. 그 결과 경비원은 낮은 보수와 후생복지의 취약 등으로 인해 업무 숙련도가 떨어지고 사기가 저하될 뿐더러 양질의 서비스를 기대하기 어려운 것이 현실이다. 또한 민간경비 분야의 전문 인력 양성체재에 대한 교육 및 훈련과 전문 인력에 대한 자격인증제도도 미흡한 실정이다. 이러한 문제에 적극적으로 대응하기 위한 방안 중의 하나로 자격제도를 활성화시키는 방안을 들 수 있다. 따라서 주요 국가 및 한국의 민간경비 관련 자격제도들의 현황을 조사한 후 문제점을 분석하여 다음과 같은 개선방안을 제시하고자 한다. 첫째, 경비지도사 자격제도는 경비지도사의 직무와 직접 관련성이 높은 과목을 검정하고, 실기시험을 추가하며, 경비 업무별 실기 위주의 교육과 정기적인 보수 교육 등이 필요하다. 또한 민간경비 산업에서 실질적으로 필요한 인원을 정확히 파악하여 검정하며, 1차 시험 면제 대상의 축소가 요구된다. 둘째, 경비원 직무교육 과목은 법적으로 명시되어야 하며, 경호 경비와 관련된 학력 및 경력자들에게 경비원 교육 과목을 일부 면제 해주거나 평가만을 통한 이수방법이 필요하다.

• 한국컴퓨터정보학회지
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• 제14권1호
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• pp.221-228
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• 2006

본 논문에서는 자격증에 대한 정보와 필기 및 실기평가 문제가 데이터베이스화되어 있어 쉽게 접근할 수 있는 능동적인 학습 방법을 제시한다. 먼저, 가중치에 의한 사용자 프로파일의 정보를 이용하여 사용자의 특성에 맞는 문제를 필터링하여 제공함으로써 개별 평가가 가능하고 학습의 동기를 증진시키고 성취감을 느끼게 해준다. 그리고 자격증취득에 대한 지도와 관리를 통해 자격증 취득률을 향상시키고 진로에 대한 적극적인 관심과 인식을 새롭게 할 것이다.

• 한국산업융합학회 논문집
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• 제25권4_2호
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• pp.663-671
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• 2022

Practice through virtual reality can increase the educational effect regardless of time and place, and it is an educational method that is being pursued even in the situation of COVID-19. On the other hand, for VR-based education, related technology development and content development must be made, and experiential methods (flipped learning, blended learning, hybrid learning) must be provided in the educational process. The development scenario was developed with the contents of drone qualification test (ultra-light unmanned multicopter) and drone practice and the possibility of non-face-to-face self-directed learning (flipped learning, blended learning, hybrid learning). It is expected that the quality of vocational education related to drones and the effect of high education will be improved through the contents, and it is thought that it will be possible to suggest a direction for the development of various vocational education contents in non-face-to-face education.

• 한국IT서비스학회지
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• 제17권4호
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• pp.53-74
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• 2018

This study theoretically examines the essence of the competencies, qualifications and grades newly required in the era of the 4th industrial revolution, points out that the engineer rating system does not reflect the new talent and practical capability, and conducts theoretical and empirical analyzes on improvement of the rating system. The current rating system need to be improved because it is not possible for graduates and experience workers to upgrade. Also, it is reasonable that the current highest grade of engineer, the Professional Engineer, which is a sort of qualification, is not a grade but a function of calculating the grade. Based on this theoretical background, empirical analysis of the question investigation and focus group interview shows that the rating system should be improved to four grades or return to the previous system in 2013. And if it is reduced to four grade, it should go in the way that the professional engineer and the qualified engineer combined. In the industry, the future skills of engineers are as follows : qualification, ability to use emerging technology, problem solving, understanding and utilization of major, and data management, etc. These can be summarized as qualification, education (degree) and career. In particular, the engineering industry considers qualifications, degrees, and career experience, and career experience as the most important elements of the rating system. In this regard, it is necessary to introduce a method that accurately reflects the career experience in the improvement of the engineer rating system.