The laser power has been continually increased since the laser was developed in the mid-20th century. Achieving higher laser power requires not only enhancing the cooling performance of laser systems but also addressing the potential degradation of optical characteristics due to thermal deformation induced by laser beam absorption in a mirror. This study delves into the thermal deformation characteristics of mirrors in high-power laser systems. To minimize thermal deformation by heat absorption, Zerodur, known for its low coefficient of thermal expansion, was employed as the mirror material. Various configurations including circular, rectangular, and spline shapes were implemented on a solid mirror structure. Furthermore, two different diameter of a mirror, 300mm and 400mm, were considered to investigate the size effect of the high-power laser beams. Also, three different transmitted beam power were adopted: 50W, 250W, and 500W. Based on the finite element analysis for the thermal deformation, the deformation characteristics of the different types of mirror structures were investigated and analyzed for high-power laser systems.

항만 내 선박과 부두의 사고를 예방하기 위하여 통항 및 접안 안전성 평가를 통하여 안전한 부두가 건설되어 관리하고 있으나, 선 박의 접안 및 계류 과정에서 선박이 부두에 충돌하거나 로프로 인한 인명사고의 발생 등 예측할 수 없는 사고들이 종종 발생한다. 자동계류장 치는 선박의 신속하고 안전한 계류를 위한 자동화된 시스템으로 로봇 매니퓰레이터와 흡착 패드로 구성된 탈/부착 메커니즘을 가지고 있다. 본 논문은 자동계류장치의 흡착 패드의 위치 및 속도제어에 필요한 선체와의 변위 및 속도 측정 시스템을 다룬다. 자동계류장치에 적합한 측 정 시스템을 설계하기 위하여, 본 논문은 우선 센서의 성능 및 실외 환경적 특성 분석을 수행한다. 다음으로 이러한 분석 결과를 토대로 실외 부두환경에서 설치되는 자동계류장치에 적합한 변위 및 속도 측정시스템의 구성 및 설계 방법에 대해 기술한다. 또한 센서의 측정상태 감지 및 속도 추정을 위한 알고리즘을 제시한다. 제안된 방법은 다양한 속도 구간에서의 변위 및 속도 측정 실험을 통해 그 유용성을 검증한다.

This research introduced a command-filtered backstepping control of mirror system to maintain laser communication between satellite and ground station. This requires a 2 degree of freedom gimbal mirror system using DC motors for target acquisition, pointing, and tracking (APT) system. This APT system is used for laser communication between satellite and ground stations. To track these desired angles, we have to control DC motors using introduced command-filtered backstepping controller (CFBSC) with disturbance. Command filtered backstepping controller has second order filter instead differentiation for simple and fast calculation. Introduced command-filtered backstepping control gives a smooth control signal for intermediate states. Simulation results verify that CFBSC outperforms SMC in terms of tracking error and disturbance rejection.

Laser scabbling has the potential to be a valuable technique capable of effectively decontaminating highly radioactive concrete surface at nuclear decommissioning sites. Laser scabbling tool using an optical fiber has a merits of remote operation at a long range, which provides further safety for workers at nuclear decommissioning sites. Furthermore, there is no reaction force and low secondary waste generation, which reduces waste disposal costs. In this study, an integrated decontamination system with laser scabbling tool was employed to test the removal performance of the concrete surface. The integrated decontamination system consisted of a fiber laser, remote controllable mobile cart, and a debris collector device. The mobile cart controlled the translation speed and position of the optical head coupled with 20 m long process fiber. A 5 kW high-powered laser beam emitted from the optical head impacted the concrete block with dimensions of 300 mm × 300 mm × 80 mm to induce explosive spalling on its surface. The concrete debris generated from the spalling process were collected along the flexible tube connected with collector device. We used a three-dimensional scanner device to measure the removed volume and depth profile.

Laser cutting has been recognized as one of key techniques in dismantling nuclear power plants as it has several advantages such as a remote operation and a reduced secondary waste. However, it generates a significant amount of aerosols that can pose a health risk to workers and further induce environmental pollution during the cutting operation. Thus, understanding the aerosol characteristics generated by the laser cutting is crucial for implementing an effective cutting operation and reducing the exposure to these hazardous particles. In this work, we established a methodology to collect the aerosols and investigate their properties in the laser cutting operation. We built an integrated laser cutting system for aerosol analyses, consisting of a high-power laser cutting module, a metal sample holder, an aerosol collector, and a closed chamber. We expect that this system will offer an opportunity for in-depth understanding of the aerosol properties, by connecting it with desired type of aerosol analysis platforms, and further safe dismantling operation of the nuclear power plants.

The paint removal of fighter jets is just as important as the painting, because perfect paint removal ensures the quality of the exterior painting on the aircraft. However, the current conditions for paint removal work of the ROKAF’s are poor. It is identified that the painting process currently implemented by the ROKAF is not only exposed to harmful compounds such as harmful dust and hexavalent chromium, but also consumes a lot of water. Thus, the introduction of advanced facility is considered. This study compares the fighter jets painting removal process currently applied by the Korean Air Force with the improved laser coating removal process of the US Air Force, and conducts an incremental analysis to perform economic analysis for the introduction of advanced facility. Four scenarios were envisioned on the premise of an increase in the number of fighters in the future, incremental analysis shows that laser coating removal method is advantageous in all scenarios. In addition, it is recommended that paint removal cycle keeps the current 12-year and the outsourcing amount to civilian depot is reduced.

This study presents an example of creating and optimizing a task sequence required in an automated remote dismantling system using a digital manufacturing system. An automated remote dismantling system using a robotic arm has recently been widely studied to improve the efficiency and safety of the dismantling operations. The task sequence must be verified in advance through discrete eventbased process simulation in a digital manufacturing system to avoid problems in actual remote cutting operations as the main input of the automated remote dismantling system. The laser cutting method can precisely cut complicated target structures such as reactor internals with versatility, but a robot and a pre-prepared program are required to deploy sophisticated motion of the laser cutting head on the target structure. For safe and efficient dismantling operations, the robot’s program must be verified in advance in a virtual environment that can represent the actual dismantling site. This study presents creating and optimizing the task sequence of a robotic underwater laser cutting as part of the project of developing an automated remote dismantling system. A task sequence is created to implement the desired cutting path for the target structure using the automated remote dismantling system in the virtual environment. The task sequence is optimized for the posture of the laser cutting head and the robot to avoid collisions during the operation through discrete event-based process simulation since the target structure is complicated and the volume occupied by the laser cutting head and the robot arm is considerably large. The task sequence verified in the digital manufacturing system is demonstrated by experiments cutting the target structure along the desired cutting path without any problems. The various simulation cases presented in this study are expected to contribute not only to the development of the automated remote dismantling system, but also to the establishment of a safe and efficient dismantling process in the nuclear facility decommissioning.

This study develops a new device system for measuring a slope of object with non-adhesive, non-contact and non-face-to-face, namely Inclinometer Slope Laser Measuring (ISLM), that is applicable in the field. This system includes cradle, laser, camera, and computer and the filming and is performed after laser projection at programmed intervals. After measuring the amount of displacement converted to numerical values, these values can then be transferred to the office using the selected data transmission method. The obtained results from the test carried out to verify the reliability of the ISLM system indicated that the ISLM system can measure with accurately level of 0.1mm/Pixel at 1m distance and when increasing the camera resolution, the precision might increase proportionally. Therefore, the proposed measure system may widely apply on-site for various constructions, especially, in the case of object with very high surface temperature where exhibits difficulty to directly measure the adjacent structures. However, due to the sensitive reaction to the illuminance, this method can be applied with caution at times of large changes in illuminance, such as at dawn and at dusk.

슬로싱과 같은 액체의 동적 거동을 측정하고 제어하는 연구가 다양한 공학분야에서 활발히 진행중이다. 건축공학분야에서 도 건축물의 풍진동을 저감시키는 동조액체감쇠기의 연구에 액제 진동이 측정되고 있다. 본 논문에서는 기존 파고 측정 센서의 한계를 극복하기 위하여 레이저 장비 중 LDV와 스캐닝 장비 중 갈바노미터스캐너를 이용하여 동조액체감쇠기 내의 액체 진동을 측정하는 방법을 제안하고 검증하였다. LDV가 속도와 변위를 측정하는 원리를 기술하였고 갈바노미터스캐너의 구동 원리에 따라 LDV의 단일 포인트로 다점측정이 가능한 시스템을 구성하였다. 동조 액체감쇠기의 4점 액체 진동을 측정하여 각 점의 시간 영역 데이터를 기존에 사용하던 비디오 센싱 데이터와 비교하였고 파형 분석을 통해 진행파와 정상파를 구별할 수 있음을 확인하였다. 또한 측정 딜레이가 있는 데이터를 상호 상관을 취하여 특이값 분해를 하고 이론 및 비디오 센싱 결과와 일치하는 고유진동수와 모드형상을 도출하였다.

Unloading operation by the unloader is dependent on the experience of the operator in the cabin. If the operator receives information about the unloading situation in the process of lifting the bucket, it is possible to prevent the collision of the bucket with the ship structure. In recent years, numerous measurement systems have become available on the market for three-dimensional surveying of objects, but they are very expensive. This study presents a high quality, low cost 3D laser scanning system designed for object recognition. The developed 3D laser scanning system is built on the base of a 2D laser sensor by the extension with a servo motor and a rotation module. In order to evaluate performance of the developed 3D laser scanning system, the developed system was applied to scan a shape of hatch and cargo holder on a cargo ship. Experimental results showed that to obtain a 3D scanning data for the area around the hatch and cargo holder.

In this paper, we describe experiment results using a vibration assisted hybrid femtosecond laser (λ:795 nm) ultra- precision machining system. The hybrid system we have developed is possible that optical focal point of the femtosec- ond laser constantly and frequently within the range of PZT(piezoactuator) vibrator working distance. Using the hybrid system, We have experimented on brass and studied about differences of result of hole aspect ratio compare to general experiment setup of femtosecond laser system. Aspect ratio of a micro hole on brass is increased as 54% with 100 Hz vibration frequency and surface roughness of the side wall also improved compare to non-vibration.

한국원자력연구원 내 지하 처분 연구시설(KURT)에서 채취한 지하수에 존재하는 나노 콜로이드 입자의 크기 및 농도를 현장에서 조사하기 위해 이동식 레이저 유도 파열 검출 장치를 개발하였다. 제작한 장치는 CCD 카메라를 이용하여 레이저 유도 플라즈마가 발생한 위치를 2-차원 영상으로 기록함으로써 광학적으로 입자의 크기를 결정할 수 있다. 크기가 정확히 알려진 폴리스틸렌 표준 입자를 이용하여 입자 크기 측정용 검정 곡선(calibration curve)을 구했고, 이를 이용하여 지하 처분 연구시설에서 채취한 지하수내 콜로이드 입자의 크기를 측정하였다. 지하수 내 존재하는 콜로이드 입자의 평균 크기는 108±26 nm임을 보였고, 농도는 50 ppb 이하인 것으로 추정하였다.

공초점 레이저 형광 현미경은 시료의 관찰하고자 하는 층에 대한 정보만 얻을 수 있을 뿐만 아니라 세포에 형광물질을 발광시켜 세포의 내부 단면을 볼 수 있으므로 생명과학, 의학 등 다양한 분야 에 이용될 수 있다. 본 연구에서는 파장이 488 nm인 Ar-ion 레이저를 광원으로 사용하고, NA=0.75인 배율 60x인 대물렌즈를 사용하여 레이저 스캔 공초점 형광 현미경 시스템을 구성하여 PMT(photo multiplier tube)를 통하여 파장이 505 nm의 빛이 입사되었을 때 515 nm 파장의 형광을 방출시키는 1.1 μm크기의 형광 bead 형상에 대한 정보를 얻어 Labview 프로그램으로 2차원 영상을 얻었다. 그리고 Avizo 프로그램을 사용하여 수집된 2차원 영상들을 포개는 방식으로 3차원 영상을 얻었다.

방사선차폐 laser ablation 시스템을 레이저, 미세영역의 영상 확인을 위한 이미지 시스템, XYZ 이동장치와 조절기, ablation chamber, manipulator 및 여러 가지 광학부품들로 구성하였다. Ablation용 레이저는 UOB 및 tircaloy 시편으로부터 효율적으로 시료를 채취할 수 있도록 266 nm(6 mJ)까지 파장 변환이 가능한 Nd:YAG 레이저를 선정하였으며, 이미지 시스템은 직경 50 m 크기의 crater를 판별할 수 있는 200 배율 이상의 규격을 갖춘 CCD 카메라로 선정하였다. 시편 미세이동장치는 XYZ방향으로 시편이동이 가능하고 최대 이동거리가 50 mm까지 , 그리고 최소 1m 씩 정확하게 움직일 수 있는 장치로 선정하였다. 구성된 각 단위기기들에 대하여 광학 정렬을 수행한 후, 시료채취 부위를 50 m씩 정확하게 이동하면서 레이저로 조사시킨 시료 표면을 CCD 카메라를 통하여 관찰한 결과, 표면에 생성된 crater는 원형임을 확인함으로써 단위기기별 성능을 확인할 수 있었다.