• 한국기계가공학회지
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• 제16권3호
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• pp.100-106
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• 2017

A universal outer diameter measurement module was developed using a linear variable differential transformer (LVDT). This outer diameter measurement module enables simultaneous measurement of outer diameter, displacement, and perpendicularity of bench-type high-precision products by combining analogue and digital measurement principles with mechanically precise and fine adjustment functions. The developed module showed a performance of 0.001mm in measurement resolution, 0.001mm in measurement accuracy, reference surface abrasion lower than Ra 0.1864, and measurement stability of 0.002mm. Therefore, we have acquired domestic measurement technology to improve productivity by securing technical competitiveness for universal diameter measurement technology, lower production costs through import substitution, and increased quality of products with more precise measurement technology. Furthermore, a substitution effect is expected for expensive import measurement system equipment used in production, research, and inspection sites in industries that produce precision processing products such as automobile and machine components.

• 대한조선학회논문집
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• 제52권4호
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• pp.315-322
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• 2015

In this paper, the theory of rectangular plate on the elastic foundation is used to get the relation equation between the effective Young’s modulus and the ice sheet deflection by applying the characteristic length concept, since the model ice sheet is rectangular shape in KRISO (Korea Research Institute for Ships and Ocean Engineering) ice basin. The obtained relation equation is equal to that of using the circular plate theory. A device is made and used to measure the deflection of ice plate using LVDT (Linear Variable Differential Transformer) for several loading cases and the procedure of experiments measuring the deflection used for getting the Young’s modulus is explained. In addition, the flexural strength value obtained through flexural strength experiments is compared with that of finite element analysis using the obtained effective Young’s modulus. Also, a nonlinear FEA (Finite Element Analysis) of cantilever ice beam is done with eroding effect and LS-DYNA result shows the fracture of brittle ice under 1 mm/s velocity load.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.353-354
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• 2006

The automatic inspection system is developed for the formed end part of automotive fuel pipe. The developed system has functions of outer diameter and formed end length measurement by LVDT(linear variable differential transformer) together with burr cleaning of automotive fuel pipe. The measured data are managed and controlled in real time by embedded SPC(statistical process control) program. The system is composed of mechanical part, electronic part and developed software system. These three parts operate automatically by mutual communication with each other. The developed system showed good results in finding inferior goods and efficiency improvement of the fuel pipe production line. It also eliminated the unreliable manual inspection processes and improved the confidence of product quality.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.82-87
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• 2003

Nuclear fuel with a big slenderness ratio is susceptible to flow-induced vibration under very severe conditions of high temperature, high flow and exposure to irradiation in nuclear reactor. The fuel assembly should, therefore, be designed to escape any resonance due to the vibration during the reactor operation, in particular, in case of the design changes. In addition, the amplitudes due to the grid vibration, the fuel rod vibration and the fuel assembly vibration should be minimized to reduce the grid-to-rod fretting wear. Fuel assembly vibration tests in air at room temperature and in water at high temperature have been performed to investigate fuel vibration behaviors. The frequency and damping during the test in air have been compared to those in water. Through the hydraulic test, the advanced assembly has been evaluated not to be susceptible to any resonance. In addition, the test data from the tests can be used to make fuel model and to evaluate grid-to-rod fretting wear.

• 한국생산제조학회지
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• 제20권3호
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• pp.357-360
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• 2011

Machine tools of Gantry type have been performing machine work as a moving machinery. In a large machine tools, the machinery is moving with bed and it is structurally unstable. When the objects are processed, machine tools gets loads in the direction of Z-axis. In other words, the machine tools which become bigger was performed by the trend of complexation. It made that the increased machine weight can't be passed over. In order to enhance manufacturing precision, it needs to compensate Z-axis deflection of weight for machine tools. In this paper, Machine tools of Gantry type were miniaturized and deflection was measured by LVDT sensors. When deflection was measured, block mass weighted 50kg is moving on particular distance. Then, the displacement of fixed point and moving point is measured by recording telemeter.

• 제어로봇시스템학회논문지
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• 제20권5호
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• pp.570-577
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• 2014

This paper describes the design of a force applying system for a smart phone curved glass molding system and its characteristic test. The force applying system is composed of a motor and gear, a rectilinear movement structure, a force sensor, an LVDT (Linear Variable Differential Transformer) sensor, an up and down moving block, and so on. The system precisely controls the applying force and time to the plane glass because the glass can be easily destroyed under applied force, and can be bent imperfectly. As a result of the characteristic test, the curved glass can be manufactured using this system, and the holding time under 0N force, the applying force to the plane glass, the time for applying from 0N to maximum force, and the holding time under maximum force at the manufacture feasible temperature $620^{\circ}C$ were found.

• Nuclear Engineering and Technology
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• 제42권2호
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• pp.203-210
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• 2010

The $\underline{H}igh$ flux $\underline{A}dvanced$ $\underline{N}eutron$ $\underline{A}pplication$ $\underline{R}eact\underline{O}r$ (HANARO), an open-tank-in-pool type reactor, is one of the multi-purpose research reactors in the world. Since the commencement of HANARO's operations in 1995, a significant number of experimental facilities have been developed and installed at HANARO, and continued efforts to develop more facilities are in progress. Owing to the stable operation of the reactor and its frequent utilization, more experimental facilities are being continuously added to satisfy various fields of study and diverse applications. The irradiation testing equipment for nuclear fuels and materials at HANARO can be classified into capsules and the Fuel Test Loop (FTL). Capsules for irradiation tests of nuclear fuels in HANARO have been developed for use under the dry conditions of the coolant and materials at HANARO and are now successfully utilized to perform irradiation tests. The FTL can be used to conduct irradiation testing of a nuclear fuel under the operating conditions of commercial nuclear power plants. During irradiation tests conducted using these capsules in HANARO, instruments such as the thermocouple, Linear Variable Differential Transformer (LVDT), small heater, Fluence Monitor (F/M) and Self-Powered Neutron Detector (SPND) are used to measure various characteristics of the nuclear fuel and irradiated material. This paper describes not only the status of HANARO and the status and perspective of irradiation devices and instrumentation for carrying out nuclear fuel and material tests in HANARO but also some results from instrumentation during irradiation tests.

• 한국전산구조공학회논문집
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• 제27권5호
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• pp.353-360
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• 2014

본 논문에서는 국내 선박해양플랜트연구소에 구축된 빙해수조의 빙특성 중에서 모형빙의 두께와 유효탄성계수 산출과정이 소개되었다. 수조에서 결빙되는 빙판은 크기가 가로 세로각각 30 m 정도에 두께는 40mm정도이다. 모형선의 실험결과를 쇄빙선 설계에 사용하기 위하여 빙 특성 정보가 필요하다. 사람이 빙판을 일부 절개하고 일일이 손으로 두께를 측정하는 것을 지양하기 위하여 초음파 기기를 사용하였는데 저주파 장비를 사용하여 작은 샘플 모형빙에 대한 두께는 계측되었다. 하지만 완벽한 계측을 위해서는 송수신 일체형 저주파 센서나 정확한 위치가 설정된 분리형 센서 혹은 고가의 특수 장치가 필요함을 확인하게 되었다. 한편 빙판의 처짐량을 간이식 LVDT로 계측하고 이를 탄성체 위에 놓인 무한 판의 특성길이 관계식에 대입하여 빙의 유효탄성계수를 산출하였는데 외국의 결과와 유사함이 입증되었다.

• Geomechanics and Engineering
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• 제21권2호
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• pp.95-102
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• 2020

Population concentration in urban areas has led traffic management a central issue. To mitigate traffic congestions, the government has planned to construct large-cross-section tunnels deep underground. This study focuses on estimating the damage caused to frame structures owing to tunnel excavation. When constructing a tunnel network deep underground, it is necessary to divide the main tunnel and connect the divergence tunnel to the ground surface. Ground settlement is caused by excavation of the adjacent divergence tunnel. Therefore, predicting ground settlement using diverse variables is necessary before performing damage estimation. We used the volume loss and cover-tunnel diameter ratio as the variables in this study. Applying the ground settlement values to the settlement induction device, we measured the extent of damage to frame structures due to displacement at specific points. The vertical and horizontal displacements that occur at these points were measured using preattached LVDT (Linear variable differential transformer), and the lateral strain and angular distortion were calculated using these displacements. The lateral strain and angular distortion are key parameters for structural damage estimation. A damage assessment chart comprises the "Negligible", "Very Slight Damage", "Slight Damage", "Moderate to Severe Damage", and "Severe to Very Severe Damage" categories was developed. This table was applied to steel frame and concrete frame structures for comparison.

• Structural Engineering and Mechanics
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• 제73권4호
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• pp.427-436
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• 2020

The use of final IGS precise orbit and clock products for high-rate GNSS-PPP proved its effectiveness in capturing dynamic displacement of engineering structures caused by earthquakes. However, the main drawback of using the final products is that they are available after approximately two weeks of data collection, which is not suitable for timely measures after an event. In this study, the use of ultra-rapid products (observed part), which are available after a few hours of data collection, and rapid products, which are available in less than 24 hrs, are investigated and their results are compared to the more precise final products. The tests are designed such that harmonic oscillations with different frequencies and amplitudes and ground motion of a simulated real earthquake are generated using a single axis shake table and the PPP was used to capture these movements by monitoring time-change of the table positions. To evaluate the accuracy of PPP using ultra-rapid, rapid and final products, their results were compared with relative GNSS positioning and LVDT (Linear Variable Differential Transformer) data, treated as reference. The results show that the high-rate GNSS-PPP solutions based on the three products can capture frequencies of harmonic oscillations and dynamic displacement with good accuracy. There were slight differences between ultra-rapid, rapid and final products, where some of the tested events indicated that the latter two produced are more accurate and provide better results compared to the ultra-rapid product for monitoring short-term dynamic displacements.