• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
• /
• pp.317-318
• /
• 2006

The towfish oi a side scan sonar is an equipment that search images of the bottom surface of the sea in real time. It is a typical equipment that is related to a sea investigation such as a geological survey, seabed communication cable and power line cable placing repair investigation, fish breeding ground investigation, sea purification, relic and mineral investigation, and mine and submarine search. It used to find objects and Investigate on the seabed surface. But, recently, it is used to sea purification and geological survey that require information of the correct surface of the seabed. So, it needs various filtering technique and image processing techniques development to acquire high resolution image. Therefore, this research develops a side scan sonar using multi-beam sensors that supply various information with the fast scan speed and correct high resolution that is not a simple underwater investigation equipment.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.582-587
• /
• 2004

Ultrasonic sensors are widely used in mobile robot applications to recognize external environments, because they are cheap, easy to use, and robust under varying lighting conditions. However, the recognition of objects using a ultrasonic sensor is not so easy due to its characteristics such as narrow beam width and no reflected signal from a inclined object. As one of the alternatives to resolve these problems, use of multiple sensors has been studied. A sequential driving system needs a long measurement time and does not take advantage of multiple sensors. Simultaneous and pulse coding driving system of ultrasonic sensor array cannot measure short distance as the length of the code becomes long. This problem can be resolved by multi-frequency driving of ultrasonic sensors, which allows multi-sensors to be fired simultaneously and adjacent objects to be distinguished. Accordingly, this paper presents a simultaneous and multi-frequency driving system for an ultrasonic sensor array for object recognition. The proposed system is designed and implemented using a DSP and FPGA. A micro-controller board is made using a DSP, Polaroid 6500 ranging modules are modified for firing the multi-frequency signals, and a 5-channel frequency modulated signal generating board is made using a FPGA. To verify the proposed method, experiments were conducted in an environment with overlapping signals, and the flight distances for each sensor were obtained from filtering of the received overlapping signals and calculation of the time-of-flights.

• 한국측량학회지
• /
• 제28권1호
• /
• pp.39-46
• /
• 2010

수심측량 자료는 선박의 항행안전을 위한 필수자료이며 해양의 합리적 이용과 보전을 위한 기초자료이다. 최근 IT기술과 측위장비(GPS와 INS), 수심관측 장비(Echo Sounder)의 발달로 멀티빔(Multi Beam Echo Sounder) 방식을 이용하여 정밀한 해저지형 자료DB를 구축하고 있다. MBES 자료에는 다양한 요인으로 인하여 오차를 포함하고 있으며, 일부 자료에서 지형이 지그재그한 물결현상을 발생하는 오차들이 발생한다. 물결무늬를 발생시키는 오차는 MBES 자료 처리결과의 정확도를 저해하는 요인이며, 발생 원인을 파악하여 이러한 오측자료 제거를 통하여 정확도를 향상시키고자 한다. 본 연구에서는 MBES 자료를 이용하여 물결 무늬 현상이 발생하는 자료에 대한 Motion sensor 값을 분석하여 오측자료의 원인을 파악하였다 분석결과, 물결무늬 현상은 Roll의 표준편차와 상관관계를 갖으며, 이러한 물결무늬 오측자료는 급격한 Roll 값의 변화로 인하여 Swath 자료와 Roll 값의 불일치 결과로 나타났다. 이를 근거로 Swath 자료의 기울기와 Roll 값의 비교하여 오측자료를 선별하여 제거하였다 오측자료를 제거한 결과. Motion sensor의 Roll 값의 표준연차 등을 이용하여 MBES 자료의 품질을 판단하고, 불일치 자료를 최소화하는 추가적인 오차 요인을 계산할 수 있을 것이라 예상된다 또한, 해황조건이 고르지 못한 상황 및 Sensor의 움직임이 크게 일어나는 소형 선박 등에 척용을 하면 수심측량 정확도 개선에 기여할 수 있을 것이다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2006년도 정기 학술대회 논문집
• /
• pp.159-166
• /
• 2006

Although the strain distribution along the length of a beam in buildings or infrastructures is non-uniform, most fiber optic sensors are point sensors that can measure the strain only at a local point of a beam. Long gage fiber optic sensors that measure integrated strain over a relatively long length can consider strain variation. This type of sensor was found to be efficient and useful for monitoring large-scale structures. On the other hand, the maximum strain or stress in a beam can not be measured with long gage optic sensors. However, for the assessment of the safety of multi-span steel beams subjected to various vertical loads, the maximum strain or stress measured during monitoring is required for comparison with the allowable stress of the beam calculated by a design code. Therefore, in this paper, mathematical models are presented for determination of the maximum values of strains in more three-span steel beams based on the average strains measured by long gage optic sensors.

• 대한기계학회논문집A
• /
• 제30권6호
• /
• pp.698-704
• /
• 2006

This paper presents an electrode shape design method for the multi-mode sensors that could deteict the selected structural multiple modes. The structure used for this study is an isotropic cantilever beam type with a PVDF (polyvinylidene fluoride) which is bonded onto the structure as a sensor. The shape optimization problem is solved by using Genetic Algorithm (GA) with an appropriate objective function. The performance of analytical optimal shape sensor is compared with that of experimental work. The results show that the, obtained electrode shape sensors have good performance to detect the multiple vibration modes simultaneously.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 추계학술대회 논문집
• /
• pp.450-453
• /
• 1995

The beam rotating actuator, which can be utilized to improve the data transfer rate for the optical disk systems, has been developed. It can employ a newly developed laser beam rotating actuator for putting multi-beam spots on more than one track on the optical disk simultaneously. Therefore, It has to maintain up to .+-.0.01 .deg. resolution and high bandwidth performance. In this these, the Dove prism is used for the beam rotating actuator based on bimorph piezo material. The performance of the beam rotating actuator is verified since the dynamics ferquency performance is measured using the dynamic analyzer and the attached stain gage sensor. the beam rotating angle performance is also examined since the long range beam reflection character is utilized.

• 소성∙가공
• /
• 제20권5호
• /
• pp.333-338
• /
• 2011

Rapidly developing IT technologies in recent years have raised the demands for high-precision optical lenses used for sensors, digital cameras, cell phones and optical storage media. Many techniques are required to manufacturing high-precision optical lenses, including multi-beam sensing lenses investigated in the current study. In the case of injection molding for thick lenses, a shrinkage phenomenon often occurs during the process. This shrinkage is known to be the main reason for the lower optical quality of the lenses. In the present work, a CAE analysis was conducted simultaneously with experiments to understand and minimize this phenomenon. In particular, the sectional area of a gate was varied in order to understand the effects of packing and cooling processes on the final shrinkage pattern. As a result of this study, it was demonstrated that a dramatic reduction of the shrinkage could be obtained by increasing the width of the gate.

• 한국전기전자재료학회논문지
• /
• 제35권2호
• /
• pp.165-171
• /
• 2022

The SiO₂/TiO₂ multilayer thin films used for narrow band pass filter were fabricated using E-beam evaporation method. The narrow band pass filter was used to enhance the resolution of spectroscopy and sensor applications with near infrared (NIR) light source. The narrow band pass filter with multilayer thin films were designed with Essential Macleod program. The multilayers of SiO₂/TiO₂ with 32 layers were deposited on the silicon encapsulation of IR with peak wavelength (λ_p) of 660 nm and NIR LEDs with λ_p of 830 nm, 880 nm, and 955 nm. After NIR light passed through the narrow band pass filter, the full width of half maximum of 33.4~48.6 nm became narrow to 20~24 nm owing to the absorption of photons with short or long wavelength of designed band of 20 nm. The SiO₂/TiO₂ band pass filter fabricated in this study can be used for sensor, optoelectronics, and NIR spectroscopy applications.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
• /
• pp.260-265
• /
• 1996

Active control of forced vibration response of a fixed-fixed beam implementing PZT sensor/actuator was conducted. Among various control scheme, PPF control was chosen due to its amenability and natural robustness. For a single frequency excitation, the PPF control provided reasonable controllability with the appropriate damping ratio of the compensator. Without increasing actuator voltage, best controllability can be obtained by the exact tuning between the natural frequency of the structure and the cut-off frequency of the compensator. Even the multi-frequency excitation, the PPF provided good vibration suppression for corresponding mode of interest, even though residual modes should be controlled with independent compensators for each mode.

• Smart Structures and Systems
• /
• 제6권5_6호
• /
• pp.561-578
• /
• 2010

This study proposes a multi-level damage localization strategy to achieve an effective damage detection system for civil infrastructure systems based on wireless sensors. The proposed system is designed for use of distributed computation in a wireless sensor network (WSN). Modal identification is achieved using the frequency-domain decomposition (FDD) method and the peak-picking technique. The ASH (angle-between-string-and-horizon) and AS (axial strain) flexibility-based methods are employed for identifying and localizing damage. Fundamentally, the multi-level damage localization strategy does not activate all of the sensor nodes in the network at once. Instead, relatively few sensors are used to perform coarse-grained damage localization; if damage is detected, only those sensors in the potentially damaged regions are incrementally added to the network to perform finer-grained damage localization. In this way, many nodes are able to remain asleep for part or all of the multi-level interrogations, and thus the total energy cost is reduced considerably. In addition, a novel distributed computing strategy is also proposed to reduce the energy consumed in a sensor node, which distributes modal identification and damage detection tasks across a WSN and only allows small amount of useful intermediate results to be transmitted wirelessly. Computations are first performed on each leaf node independently, and the aggregated information is transmitted to one cluster head in each cluster. A second stage of computations are performed on each cluster head, and the identified operational deflection shapes and natural frequencies are transmitted to the base station of the WSN. The damage indicators are extracted at the base station. The proposed strategy yields a WSN-based SHM system which can effectively and automatically identify and localize damage, and is efficient in energy usage. The proposed strategy is validated using two illustrative numerical simulations and experimental validation is performed using a cantilevered beam.