• 대한안전경영과학회지
• /
• 제16권2호
• /
• pp.43-52
• /
• 2014

In weapon systems development, live fire tests have been frequently adopted to evaluate the performance of the systems under development. Therefore, it is necessary to ensure safety in the test ranges where the live fire tests can cause serious hazards. During the tests, a special care must be taken to protect the test and evaluation (T&E) personnel and also test assets from potential danger and hazards. Thus, the development and management of the range safety process is quite important in the tests of guided missiles and artillery considering the explosive power of the destruction. Note also that with a newly evolving era of weapon systems such as laser, EMP and non-lethal weapons, the test procedure for such systems is very complex. Therefore, keeping the safety level in the test ranges is getting more difficult due to the increased unpredictability for unknown hazards. The objective of this paper is to study on how to enhance the safety in the test ranges. To do so, an approach is proposed based on model-based systems engineering (MBSE). Specifically, a functional architecture is derived utilizing the MBSE method for the design of the range safety process under the condition that the derived architecture must satisfy both the complex test situation and the safety requirements. The architecture developed in the paper has also been investigated by simulation using a computer-aided systems engineering tool. The systematic application of this study in weapon live tests is expected to reduce unexpected hazards and test design time. Our approach is intended to be a trial to get closer to the recent theme in T&E community, "Testing at the speed of stakeholder's need and rapid requirement for rapid acquisition."

• 대한치과보철학회지
• /
• 제41권6호
• /
• pp.762-771
• /
• 2003

Statement of problem. In dentistry, the minimally prepared inlay resin-bonded fixed partial denture (FPD) made of new ceromer / fiber-reinforced composite (FRC) was recently introduced. However, the appropriate dimensions for the long-term success and subsequent failure strength are still unknown. Purpose. The aim of this study was to investigate the most fracture-resistible thickness combination of the ceromer / FRC using a universal testing machine and an AE analyzer. Material and Methods. A metal jig considering the dimensions of premolars and molars was milled and 56-epoxy resin dies, which had a similar elastic modulus to that of dentin, were duplicated. According to manufacturer's instructions, the FRC beams with various thicknesses (2 to 4 mm) were constructed and veneered with the 1 or 2 mm-thick ceromers. The fabricated FPDs were luted with resin cement on the resin dies and stored at room temperature for 72 hours. AE (acoustic emission) sensors were attached to both ends, the specimens were subjected to a compressive load until fracture at a crosshead speed of 0.5 mm/min. The AE and failure loads were recorded and analyzed statistically. Results. The results showed that the failure strength of the ceromer/FRC inlay FPDs was affected by the total thickness of the connectors rather than the ceromer to FRC ratio or the depth of the pulpal wall. Fracture was initiated from the interface and propagated into the ceromer layer regardless of the change in the ceromer / FRC ratio. Conclusion. Within the limitations of this study, the failure loads showed significant differences only in the case of different connector thicknesses, and no significant differences were found between the same connector thickness groups. The application of AE analysis method in a fiber-reinforced inlay FPD can be used to evaluate the fracture behavior and to analyze the precise fracture point.

• Journal of Information Processing Systems
• /
• 제14권3호
• /
• pp.751-770
• /
• 2018

Web applications are indispensable in the software industry and continuously evolve either meeting a newer criteria and/or including new functionalities. However, despite assuring quality via testing, what hinders a straightforward development is the presence of defects. Several factors contribute to defects and are often minimized at high expense in terms of man-hours. Thus, detection of fault proneness in early phases of software development is important. Therefore, a fault prediction model for identifying fault-prone classes in a web application is highly desired. In this work, we compare 14 machine learning techniques to analyse the relationship between object oriented metrics and fault prediction in web applications. The study is carried out using various releases of Apache Click and Apache Rave datasets. En-route to the predictive analysis, the input basis set for each release is first optimized using filter based correlation feature selection (CFS) method. It is found that the LCOM3, WMC, NPM and DAM metrics are the most significant predictors. The statistical analysis of these metrics also finds good conformity with the CFS evaluation and affirms the role of these metrics in the defect prediction of web applications. The overall predictive ability of different fault prediction models is first ranked using Friedman technique and then statistically compared using Nemenyi post-hoc analysis. The results not only upholds the predictive capability of machine learning models for faulty classes using web applications, but also finds that ensemble algorithms are most appropriate for defect prediction in Apache datasets. Further, we also derive a consensus between the metrics selected by the CFS technique and the statistical analysis of the datasets.

• 한국지반신소재학회논문집
• /
• 제13권4호
• /
• pp.119-131
• /
• 2014

본 연구에서는 광역 부지나 현장 접근성이 용이하지 않은 현장의 지반조사를 신속 정확하게 수행하기 위한 목적으로 해외에서 널리 사용되고 있는 동적 콘 관입시험기를 개선한 개량형 동적 콘 관입시험기를 개발하였다. 기존의 동적 콘 관입시험기의 장점인 휴대성, 간단한 시험방법 등은 그대로 반영하는 한편, 하부 로트의 결합 연장을 통하여 기존 시험기의 지반 관입심도 1m에서 6m까지 관입되도록 고안하였다. 또한, 해머(2+3+3kg), 콘(3type) 등의 조합으로 독일식/일본식 간이 동적 콘 관입시험기(Tsukuba, PWRI, SH type)와 동일한 제원으로 시험이 가능하며, 심도가 깊어짐에 따라 시험 결과에 영향을 미치는 수직도를 확보할 수 있도록 보조 장치를 적용시켰다. 이렇게 개발 제작한 개량형 동적 콘 관입시험기의 적용성을 평가하기 위하여 국내/외 현장의 다양한 지반에 대하여 시험을 수행하여 그 신뢰성을 확보하였다.

• 한국태양에너지학회 논문집
• /
• 제37권4호
• /
• pp.35-47
• /
• 2017

Energy efficiency solutions are being pursued as a sustainable approach to reducing energy consumption and related gas emissions across various sectors of the economy. Vacuum Insulation Panel (VIP) is an energy efficient advanced insulation system that facilitates slim but high-performance insulation, based on a porous core material evacuated and encapsulated in a barrier envelope. Although VIP has been applied in buildings for over a decade, it wasn't until recently that efforts have been initiated to propose and adopt a global standard on characterization and testing of VIP. One of the issues regarding VIP is its durability and aging due to pressure and moisture dependent increase of the initial low thermal conductivity with time; more so in building applications. In this paper, the aging of commercially available VIP was investigated experimentally; thermal conductivity was tested in accordance with ISO 8302 standard (guarded hot box method) and long-term durability was estimated based on a non-linear pressure-humidity dependent equation based on study of IEA/ECBCS Annex 39, with the aim of assessing durability of VIP for use in buildings. The center-of-panel thermal conductivity after 25 years based on initial 90% fractile with a confidence level of 90 % for the thermal conductivity (${\lambda}90/90$) ranged from 0.00726-0.00814 (W/m K) for silica core VIP. Significant differences between manufacturer-provided data and measurements of thermal conductivity and internal pressure were observed.

• 한국광학회지
• /
• 제17권5호
• /
• pp.412-419
• /
• 2006

초정밀 비구면 기공기로 제작한 구경 300 mm이고 f-수가 1.98인 알루미늄 쌍곡면 거울의 형상을 측정하기 위하여 자동무수차점 널(null) 렌즈 광학계를 설계하고 제작하였으며, 이를 이용하여 이 대구경 쌍곡면 거울의 형상을 측정하였다. 이때 널 렌즈간 정렬은 구조적으로 안정하고 부피가 작은 경통고정식을 선택하였고, 널 렌즈 및 경통의 제작 허용오차는 요구되는 측정 정밀도를 만족하도록 공차분석기법을 통하여 계산하고 제작하였다.

• 대한토목학회논문집
• /
• 제39권1호
• /
• pp.239-246
• /
• 2019

드론사진측량(Drone photogrammetry)은 높은 정확도의 공간정보획득과 각종 모니터링 목적으로 활발히 활용되고 있다. 요구하는 정확도를 얻기 위한 드론사진측량 계획 시 경험 또는 기존의 사례를 참고하여 계획하는 경우가 일반적이나 불량한 정확도로 인하여 재 촬영하는 경우가 종종 발생한다. 요구하는 드론사진측량 처리결과의 공간정확도는 결과물의 종류에 관계없이 객관적인 평가의 수단이 되므로 신중히 결정할 필요가 있다. 따라서 드론사진측량의 프로젝트설계는 요구하는 공간정확도(3D positional accuracy)를 충족시키기 위해 촬영고도, 중복도, 지상기준점(GCP; Ground Control Point)의 수와 배치, 외부표정(EO; Exterior Orientation)요소에 대한 획득방법의 결정이 필요하다. 본 연구에서는 드론사진측량 정확도분석에 대한 기존 연구사례를 면밀히 분석하고 시험지역에 적용하여 검증하였으며 이 분석결과를 토대로 소규모지역 드론사진측량 프로젝트시의 설계지침을 마련하였다. 제시한 프로젝트설계지침은 완벽하지는 않지만 실무에 많은 도움이 될 수 있을 것을 기대하며 추후 종합적분석을 통한 설계지침이 마련된다면 완벽한 매뉴얼을 제공할 수 있을 것이다.

• 한국건설순환자원학회논문집
• /
• 제8권4호
• /
• pp.413-420
• /
• 2020

이 연구에서는 펌핑 후 콘크리트의 작업성 변화를 실내에서 평가하기 위한 새로운 실험 장비를 개발하였다. 이 장비는 실제 펌핑 중 콘크리트가 받는 압력과 전단을 모사할 수 있도록 설계되었다. 실내 실험 장비를 사용한 펌핑 후 콘크리트 작업성 변화 평가 가능성을 검토하기 위하여 실규모 펌핑 실험과 실내 모사 실험을 동시에 수행하였다. 실규모 펌핑 실험에 사용한 콘크리트의 설계기준압축강도는 24, 35, 60MPa이며, 배관의 길이는 130, 304, 518m이다. 펌핑 실험과 동일한 콘크리트를 사용하여 실제 펌핑 조건(압력, 전단, 펌핑 시간)을 고려한 실내 모사 실험을 수행하였다. 실험 전, 실규모 펌핑 실험 후, 실내 모사 실험 후 콘크리트의 작업성(슬럼프 또는 슬럼프 플로)을 측정하였다. 실규모 펌핑 실험과 실내 실험 모두 콘크리트의 작업성이 감소하였으며, 두 실험의 결과가 매우 유사하게 측정되었다.

• 한국염색가공학회지
• /
• 제33권4호
• /
• pp.202-209
• /
• 2021

Natural dyes are more expensive than synthetic dyes and the dyeing process, which is mainly immersion of dye, is complicated. For this reason, relatively small-scale production methods were predominant. However, awareness and interest in environmental sustainability is rising globally, and the use of synthetic dyes causes various environmental problems such as wastewater and CO₂ emission, so the consumption of natural dyes is increasing. In addition, interest in digital textile printing, an eco-friendly dyeing method that can produce products of various designs and uses less water, is growing. In this study, natural indigo dye (Indigofera tinctoria) was used as a raw material for Digital Textile Printing ink, and ¹⁴C (Biocarbon) present in it was measured to confirm whether it was derived from natural ingredients. The performance was confirmed by testing the pH, viscosity, electrical conductivity, surface tension, and particle size analysis of natural indigo ink. In addition, the performance of natural indigo DTP ink and printing fabric was evaluated by inspecting the change in color fastness and corresponding index substances before and after digital printing with natural indigo DTP ink on textiles. Through this, the possibility of commercialization of DTP ink and printing fabric using natural indigo was confirmed.

• 한국산업융합학회 논문집
• /
• 제26권4_2호
• /
• pp.629-637
• /
• 2023

This study aimed to evaluate the effect of post-curing equipment and time on the flexural strength of 3D printing resins produced by a liquid crystal display(LCD) printer. The three 3D printing resins(DENTCA Denture Teeth, DT; C&B 5.0 hybrid, CH; C&B Permanent A2, CP) were divided into four groups according to post-curing time(10 min and 30 min) and equipment with or without vacuum treatment. For the three-point flexural strength test and biaxial strength test were prepared by method according to ISO 10477, ISO 6872, respectively. Flexural strength was measured with universal testing machine. Comparison between post-curing time of each post-curing equipment was analyzed by independent sample t-test and Mann-Whitney U test(α=.05), and comparison between groups according to each 3D printing resin was performed by Kruskal-Wallis test and post-hoc by Bonferroni-Dunn test(α=.05). The flexural strength of the resin post-curing under vacuum was higher than that of the resin post-curing in air. In the comparison according to the post-curing time, in the case of the post-curing equipment without vacuum, the 30 minute curing time showed significantly higher flexural strength than the 10 minute curing time, except for the biaxial flexural strength of CH(P<.05). In the post-curing equipment with vacuum, the three-point flexural strength of all 3D printing resins(DT, CH, and CP) showed a higher value at 30 minute curing time than at 10 minute curing time.