Korea Advanced Institute of Science and Technology

The Boeing Company

Samsung Electronics Co., Ltd.

Samsung Display Co., Ltd.

Kia Motors Corporation

Poongsan Fns Corporation

Hoon Sohn

Peipei Liu

Jeong-Beom Ihn

Soonkyu Hwang

Ikgeun Jeon

Hyung Jin Lim

Chul Min Yeum

Jiho Park

Ki-Young Kim

Sung-Il Cho

Sang-Young Kim

Minsang Koo

Sanghyuk Kwon

Cheol Beom Lim

Seung-Weon Ha

Jin-Yeol Yang

Eunchul Shin

Youn-jo Mun

Sangwoo Choi

Chulmin Yeum

Doo-Young Kang

Hyeonjin Kim

Jin Yeol Yang

Hyeon Seok Lee

Min-Jae Kim

Su Young Yang

Woojin Jung

Nam-Yeol Kwon

Hyeon-Muk Lim

Jin Ho Jang

Jin-Seok Kang

Gun-Hee Koo

Jinho Jang

Jae Roung Park

Seung-Beom Park

Zhanxiong Ma

Jae-Min Moon

Jae-Muk Choi

Jun-Yeon Chung

Byeong-Jin Park

Byeongju Song

Yun-Kyu An

Soon-Kyu Hwang

A method for detecting fatigue cracks in a structure and a system therefore are disclosed. A vibration detection element detects vibration of the structure generated when the structure is excited at low and high frequencies and generates a measurement signal in the time domain. Based on a trained long short-term memory (LSTM) network, a signal of the next time step is predicted from the measurement signal of the current time step measured by the vibration detection element. The measurement signal and the prediction signal are combined to create a new combined signal with an increased length in the time domain. The combined signal is Fourier transformed to reduce noise and enhance the information of the measured signal in the frequency domain, and the Fourier transformed signal is used to obtain a spectral density function and to detect cracks in the structure.

Method for detecting fatigue crack in structure using long short-term memory network-based spectral noise reduction and nonlinear ultrasonic modulation, and system therefor

In a method of estimating displacement of a bridge, a first displacement including a low frequency component and a first high frequency component is generated based on a strain that is measured by a plurality of pairs of strain gauges installed at positions in a first direction from a reference point, in a bridge, a second displacement including a second high frequency component is generated based on an acceleration that is measured by an accelerometer installed at a first position spaced apart from the reference point by a first distance in the first direction, in the bridge, and a final displacement of the bridge is generated based on an unknown parameter associated with the displacement, the low frequency component and the second high frequency component. The unknown parameter is generated by applying a recursive least square algorithm to the first high frequency component and the second high frequency component.

Method of estimating displacement of a bridge and an electronic device to estimate displacement of a bridge

An apparatus for inspecting a display panel for defects includes a table which supports the display panel, a laser excitation unit that irradiates a non-display area of the display panel with a point laser beam, a thermal wave detecting unit that generates thermal wave images of irradiated portions of the non-display area, a driving unit, and a control unit. A groove corresponding to an edge of the display panel may be defined in a top surface of the table. A defect, such as a crack, may be detected by comparing a defect pattern obtained from the thermal wave images with a pre-registered defect pattern.

Apparatus for inspecting a display panel for defects

Disclosed are a method of inspecting a printing quality of a 3D printing object using a femtosecond laser beam during a 3D printing process, and an apparatus and a 3D printing system for the same. A laser beam is irradiated from a femtosecond laser source disposed coaxially with a 3D printing laser source to inspect a state of the printing object. The laser beam generated by the femtosecond laser source is separated into a pump laser beam and a probe laser beam. The printing laser beam irradiated from a 3D printing laser source or the pump laser beam is irradiated onto a printing object to generate ultrasonic waves. To measure the ultrasonic waves, a probe laser beam is irradiated onto the printing object. The probe laser beam reflected by the printing object is detected. The quality of the printing object is inspected by analyzing the reflected probe laser beam.

Method of inspecting printing quality of 3D printing object using femtosecond laser beam during 3D printing process, and apparatus and 3D printing system for the same

Disclosed are a femtosecond laser-based ultrasonic measuring apparatus for a 3D printing process, and a 3D printing system including the apparatus. The apparatus includes a femtosecond laser source for generating a femtosecond laser beam irradiated to inspect a state of a printing object formed by melting a base material by a printing laser beam irradiated from the laser source for 3D printing, a beam splitter for separating the femtosecond laser beam generated by the femtosecond laser source into a pump laser beam and a probe laser beam, an electric/acoustic optical modulator for modulating the pump laser beam, a time delay unit for delaying the probe laser beam, a photo detector for detecting the probe laser beam reflected by the printing object, and a lock-in amplifier for detect an amplitude and a phase of the output signal from the photo detector. The femtosecond laser source is disposed coaxially with a laser source for 3D printing.

Femtosecond laser-based ultrasonic measuring apparatus for 3D printing process and 3D printing system having the same

A method of feedback controlling a 3D printing process in real time, and a system therefor are disclosed. The method includes collecting big data, generated through 3D printing experiments, related to process variables of 3D printing, measurement signals, and 3D printing quality of the 3D printing object; building an artificial neural network model by performing machine-learning based on the collected big data; evaluating whether or not a 3D printing quality of the 3D printing object is abnormal in real time based on an actual measurement signal of the 3D printing object and the artificial neural network model; and feedback controlling printing quality of the 3D printing object in real time based on the evaluation result of whether or not the 3D printing quality of the 3D printing object is abnormal.

Method of feedback controlling 3D printing process in real-time and 3D printing system for the same

Disclosed are a method and apparatus of estimating a depth of a molten pool formed during a 3D printing process, and a 3D printing system. A surface temperature of the molten pool is measure by taking a thermal image of a laminated printing object during the 3D printing process with a thermal imaging camera. The measured surface temperature is compared with a melting point of the base material to determine a surface boundary of the molten pool. The maximum lengths in x-axis and y-axis directions of a surface region of the molten pool defined by the surface boundary of the molten pool are determined as a length and a width of the surface of the molten pool, respectively. A maximum depth in the z-axis direction of the molten pool is determined in real time based on the length and width of the surface region of the molten pool.

Method and apparatus for estimating depth of molten pool during printing process, and 3D printing system

Disclosed are a method of inspecting and evaluating a coating state of a steel structure, and a system therefor. A plurality of vision images and thermal images are acquired. While acquiring the thermal images, a desired region is heated. After the thermal images and the vision images in a dynamic state are reconstructed into a time-spatial-integrated thermal image and a time-spatial-integrated vision image in a static state, respectively, an overlay image is generated by overlaying the two images. A deterioration region of a coating is detected, and coating deterioration is classified by characteristics. A size of the coating deterioration region is quantified. A thickness of the coating is inspected by analyzing thermal energy measured from the time-spatial-integrated thermal image. A coating grade is calculated by comprehensively evaluating a coating deterioration inspection result and a coating thickness inspection result. A state evaluation report for the steel structure is automatically created.

Method of inspecting and evaluating coating state of steel structure and system therefor

A method of performing visualized measurement on thickness distribution of a paint film and an apparatus therefor. A measurement target region is heated by a heating unit that applies a light beam while moving relative to the measurement target region of a measurement target structure. A sensing unit moving together with the heating unit generates a plurality of thermal images related to a phenomenon in which thermal energy is propagated in the measurement target region by scanning and photographing the heated measurement target region. The thermal images in a dynamic state are converted into time-spatial-integrated thermal images in a static state by performing coordinate transformation according to a time-spatial-integrated coordinate transformation algorithm. A thickness of the paint film is calculated by using a Fourier thermal conduction equation. A noise caused by an external heat source is removed by subtracting a pre-heating time-spatial-integrated thermal image from the converted time-spatial-integrated thermal image.

Method of performing visualized measurement on thickness distribution of paint film and apparatus therefor

In a method of inspecting a structure, a first ultrasonic signal generated from a target structure by a first laser beam is received. The first ultrasonic signal is generated by providing the first laser beam generated from a first excitation unit to the target structure. A second ultrasonic signal generated from the target structure by a second laser beam different from the first laser beam is received. The second ultrasonic signal is generated by providing the second laser beam generated from a second excitation unit to the target structure. A third ultrasonic signal generated from the target structure by the first and second laser beams is received. The third ultrasonic signal is generated by simultaneously providing the first and second laser beams to the target structure. It is determined whether the target structure is damaged based on first, second and third ultrasonic frequency spectra that are obtained by converting the first, second and third ultrasonic signals, respectively.

Method of inspecting structure and inspection system

Disclosed are a system and a method for precisely measuring a structure are disclosed. A reference meter installed at a fixed location provides GPS reference information. A plurality of response meters, respectively installed at a plurality of positions of the structure, acquire acceleration information through acceleration sensors and measure a plurality of real-time kinematic (RTK) displacement data based on the GPS reference information, respectively. The response meters synchronize acceleration information with the plurality of RTK displacement data measured to generate into a packet to be transmitted. An operation processor receives the acceleration information and the plurality of RTK displacement data and calculates structure response information. With the GPS and accelerometers, the dynamic behaviors of structures including high-rise buildings, bridges, dams, and harbors can be precisely measured.

System for precision measurement of structure and method therefor

A non-contact durability diagnosis apparatus includes: (a) applying non-contactly and sequentially at least two excitation ultrasonic waves to an object and storing frequency signals generated from the object; (b) applying non-contactly and simultaneously the at least two excitation ultrasonic waves to the object and storing frequency signals generated from the object; (c) storing derived frequency signals remaining after removing an overlapping portion of the frequency signals of step (a) and the frequency signals of step (b); and (d) determining that the object is damaged when at least one of the generated frequency signals of step (c) is larger than a predetermined value.

Non-contact durability diagnosis apparatus and method

The present invention relates to a safety diagnosis method for a structure using a nonlinear ultrasonic wave modulation technique. The safety diagnosis method includes: making the structure vibrate by applying signals of different ultrasonic frequencies; converting the responses of the structure generated by the vibration into digital signals; extracting first modulation signals by subtracting the harmonic responses and the linear responses of the signals of different ultrasonic frequencies from the digital signals and synchronously demodulating the digital signals; constructing a first sideband spectrogram by combining the first modulation signals generated by continuously changing at least frequency among the signals of different ultrasonic frequencies; and deciding whether the structure is cracked based on the first sideband spectrogram. Even though the power of the ultrasonic wave applied to the structure is very small as compared with the related art, whether there is the damage is precisely decided, and thus power consumption may be reduced.

Wireless diagnosis apparatus for structure using nonlinear ultrasonic wave modulation technique and safety diagnosis method using the same

A surface inspection apparatus and method of inspecting chip surfaces includes a laser generator that generates a periodic CW laser and is transformed into an inspection laser beam having a beam size smaller than a surface size of the chip. Thus, the inspection laser beam is irradiated onto a plurality of the semiconductor chips such that the semiconductor chips are partially and simultaneously heated. Thermal waves are detected in response to the inspection laser beam and thermal images are generated corresponding to the thermal waves. A surface image is generated by a lock-in thermography technique and hold exponent analysis of the thermal image, thereby generating surface image in which a surface defect is included. Time and accuracy of the surface inspection process is improved.

Surface inspection apparatus for semiconductor chips

Growing community of inventors

Daejeon, South Korea

Hoon Sohn