• 한국터널지하공간학회 논문집
• /
• 제19권2호
• /
• pp.195-212
• /
• 2017

운영 중 해저 터널의 안정성 평가에 응력, 수압 그리고 라이닝 및 주변지반의 강성 열화 등과 같은 다양한 계측 정보를 사용해서 역해석하면, 효율적인 오차율 이내의 결과를 획득할 수 있다. 선행 연구에서 검증된 차분진화 알고리즘 기반의 역해석 수행 시 FLAC3D 등 범용 지반해석 프로그램을 사용했지만, 상대적으로 해석시간이 오래 걸리고, 제어가 어려운 단점이 있다. 이러한 이유로, 본 연구에서는 상대적으로 해석시간이 짧게 소요되는 beam-spring 모델 기반의 FEM solver를 도입하였다. 원형 터널 단면의 구조해석이 가능한 beam-spring 프로그램을 Python 언어로 개발하여, 기구축된 차분진화 알고리즘과 결합하였다. 계측 데이터로부터 실시간에 가깝게 운영 중 터널의 안정성 평가가 가능할 것으로 판단된다.

• 한국터널지하공간학회 논문집
• /
• 제21권5호
• /
• pp.611-620
• /
• 2019

쉴드터널은 직경 3~4 m 규모의 전력구 등에 주로 적용되었으나, 최근 직경 7~8 m 규모의 쉴드터널이 인천국제공항 활주로 하부에 시공되었으며, 한강 하저구간 도로 및 철도터널 시공완료 및 계획중에 있다. 쉴드터널 단면이 증가함에 따라 세그먼트 또한 대형화되고 있으며, 이로 인하여 세그먼트의 설계, 시공 및 성능평가 시 여러 문제점이 야기되고 있다. 따라서 본 연구에서는 직경 약 8 m 규모의 쉴드터널에 대한 현장계측 및 실대형 하중재하 시험을 통하여 쉴드터널 세그먼트 라이닝 구조적 안정성 분석, 축력을 고려한 세그먼트 사용성 검토방안의 적합성 및 품질관리 방안에 대하여 검토하였다.

• The Journal of Advanced Prosthodontics
• /
• 제15권1호
• /
• pp.22-32
• /
• 2023

PURPOSE. Digital technology has enabled improvements in the fitting accuracy of denture bases via milling techniques. The aim of this study was to evaluate the trueness and precision of digital and analog techniques for manufacturing complete dentures (CDs). MATERIALS AND METHODS. Sixty identical CDs were manufactured using different production protocols. Digital and analog technologies were compared using the reference geometric approach, and the Δ-error values of eight areas of interest (AOI) were calculated. For each AOI, a precise number of measurement points was selected according to sensitivity analyses to compare the Δ-error of trueness and precision between the original model and manufactured prosthesis. Three types of statistical analysis were performed: to calculate the intergroup cumulative difference among the three protocols, the intergroup among the AOIs, and the intragroup difference among AOIs. RESULTS. There was a statistically significant difference between the dentures made using the oversize process and injection molding process (P < .001), but no significant difference between the other two manufacturing methods (P = .1227). There was also a statistically significant difference between the dentures made using the monolithic process and the other two processes for all AOIs (P = .0061), but there was no significant difference between the other two processes (P = 1). Within each group, significant differences among the AOIs were observed. CONCLUSION. The monolithic process yielded better results, in terms of accuracy (trueness and precision), than the other groups, although all three processes led to dentures with Δ-error values well within the clinical tolerance limit.

• Tribology and Lubricants
• /
• 제27권4호
• /
• pp.209-212
• /
• 2011

The capacitive application(prove) can be used to measure the complex permittivity of dielectric material of various thickness and cross section. This paper presents that we designed the analysis system of engine oil permittivity to know the relation between the engine oil deterioration and the prove dimension. Each of the dimension of capacitive prove is changed and then electric capacity is measured by LCR {Inductance(L), Capacitance (C), and Resistance (R)} meter. The engine oil permittivity has extracted in the prove measurement. As the additional research, this paper suggest the best of the prove dimension for the permittivity measurement.

• 한국결정성장학회지
• /
• 제5권4호
• /
• pp.408-413
• /
• 1995

초크랄스키 실리콘 기판의 뒷면에 형성된 기계적 손상이 레이저 여기/극초단파 반사 광전도 감쇠법에 의한 소수반송자 재결합 수명 측정에 미치는 영향을 고찰하였다. 기계적손상의 정도는 X-선 이중결정 회절법과 X-선 단면 측정법 및 습식산화/선택적 식각 방법으로 평가하였다. 그 결과, 웨이퍼 뒷면에 가해지는 기계적 손상의 세기가 강할수록 소수반송자 재결합 수명은 짧아지고, 소수반송자 재결합 수명 측정에 영향을 미치는 반치전폭의 임계값은 약13초임을 알 수 있다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.115-115
• /
• 2010

This paper introduces a measurement system that measures behavior and electrical characteristics of overhead contact line irregular sections in real-time. For verification, we developed a prototype of the real-time overhead contact line irregular section behavior measurement system and a monitoring system for field tests. The current and temperature of contact wires and messenger wires were measured real-time by applying the system at KTX a commercial line. Therefore, acquiring data is possible with the developed system and this system that measures one of the fundamental and key factors, the catenary current, should be applicable to various areas such as detecting characteristics for designing overhead contact lines, enhancing speed, and enhancing energy.

• Journal of Radiation Protection and Research
• /
• 제26권3호
• /
• pp.231-236
• /
• 2001

A brief introduction is presented on the radiation safety studies at Tohoku University Cyclotron & Radioisotope Center. Studies on two subject are described; (1) measurement of the thick target neutron yield and radioisotope production / activation cross section for ten's of MeV neutrons and ions using K=110 Tohoku University cyclotron to provide basicdata for accelerator shielding, and (2) development of techniques for high sensitive radiation detection and profile measurement using an Imaging Plate which is a high sensitive two-dimensional radiation sensor. Application of the Imaging Plate techniques to localization of very weak radioactivity and to neutron profile measurement is described.

• 한국소음진동공학회논문집
• /
• 제16권7호
• /
• pp.677-682
• /
• 2006

In the case of aeroacoustic test in windtunnel, measurement accuracy is reduced by not only Doppler effects but also by the microphone self noise due to airflow and high turbulence in the wall boundary layer. Microphone array measurements can be easily utilized for the solutions of these problems. In this paper, geometrical optics approach and diagonal term elimination of cross spectral matrix was introduced to the de-dopplerization and self noise reduction methods for the microphone array measurement. For the validation, beamforming tests for sinusoidal point source were performed in the closed type test section of windtunnel, and their performances of beam width and sidelobe rejection were significantly improved.

• International Journal of Contents
• /
• 제5권3호
• /
• pp.19-23
• /
• 2009

Laser scanning technology is a maturing measurement technology which is capable of obtaining 3D measurement data of objects with high-accuracy, high-resolution and in a short time. Laser scanners are used more and more as surveying instruments for various applications. This paper describes the procedure of 3D data acquirement using terrestrial LiDAR and section drawing extraction through a series of processing for remodeling the interior of a department building. Accurate drawings are needed for improvement construction of building interior. However if the design drawings of that time of construction work were lost or damaged or actual dimensions of drawings differ from those of design drawings, the interior should be resurveyed. In this study, the extraction process of interior plane figures were suggested through using laser scanning and related reverse engineering software

• 한국안전학회지
• /
• 제5권3호
• /
• pp.8-26
• /
• 1990

It is important to have exact information about the contact pressure distribution in the design of connected parts of machines and structures. In previous works, stress analyses on a two body contact problem have been carried out in large numbers. Besides, the measurement of contact stress is important to confirm the adequateness of the theoretical analysis, to verify appropriateness of Hertzian contact theory and to know the practical pressure distribution, but an excellent measuring method con't be found at present. Therefore, a quantitative measurement of contact pressure by means of ultrasonic waves using a normal probe and an angle has been proposed to measure the contact pressure distribution between two rough flat surfaces. At first, in a new proposed calibration method, the relation between mean contact pressure and sound pressure of reflected waves is obtained by using calibration blocks with various surface roughnesses made of the same material as the rectangular section beams And then, this experimental results are compared with the analytical ones, and the utility of this method is discussed.