• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1297-1303
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• 2021

Most thickness measurement techniques using X-ray radiation are unsuitable in field processes involving fast-moving organic films. Herein, we propose a Compton scattering X-ray radiation method, which probes the light elements in organic materials, and a new simple, non-destructive, and non-contact calibration-free real-time film thickness measurement technique by setting up a bench-top X-ray thickness measurement system simulating a field process dealing with thin flexible organic films. The use of X-ray fluorescence and Compton scattering X-ray radiation reflectance signals from films in close contact with a roller produced accurate thickness measurements. In a high-thickness range, the contribution of X-ray fluorescence is negligible, whereas that of Compton scattering is negligible in a low-thickness range. X-ray fluorescence and Compton scattering show good correlations with the organic film thickness (R² = 0.997 and 0.999 for X-ray fluorescence and Compton scattering, respectively, in the thickness range 0-0.5 mm). Although the sensitivity of X-ray fluorescence is approximately 4.6 times higher than that of Compton scattering, Compton scattering signals are useful for thick films (e.g., thicker than ca. 1-5 mm under our present experiment conditions). Thus, successful calibration-free thickness monitoring is possible for fast-moving films, as demonstrated in our experiments.

• 방송공학회논문지
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• 제24권4호
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• pp.580-591
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• 2019

본 논문의 목적은 자율주행을 위하여 카메라와 라이다를 이용하여 객체를 검출하고 각 센서에서 검출된 객체를 late fusion 방식으로 융합을 하여 성능을 향상하는 것을 목적으로 한다. 카메라를 이용한 객체 검출은 one-stage 검출인 YOLOv3을, 검출된 객체의 거리 추정은 perspective matrix를, 라이다의 객체 검출은 K-means 군집화 기반 객체 검출을 각각 이용하였다. 카메라와 라이다 calibration은 PnP-RANSAC을 이용하여 회전, 변환 행렬을 구하였다. 센서 융합은 라이다에서 검출된 객체를 이미지 평면에 옮겨 Intersection over union(IoU)을 계산하고, 카메라에서 검출된 객체를 월드 좌표에 옮겨 거리, 각도를 계산하여 IoU, 거리 그리고 각도 세 가지 속성을 로지스틱 회귀를 이용하여 융합을 하였다. 융합을 통하여 각 센서에서 검출되지 않은 객체를 보완해주어 성능이 약 5% 증가하였다.

• 한국측량학회지
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• 제36권6호
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• pp.525-534
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• 2018

카메라 캘리브레이션은 카메라의 초점거리, 주점위치, 렌즈왜곡 등의 매개변수를 결정하는 작업으로 이를 위해서 주로 체커보드를 촬영한 영상을 사용하고 있다. 체커보드 영상에서 타겟을 자동으로 인식할 때 기존의 연구는 사용자가 타겟인식을 위한 입력 매개변수를 잘 이해하고 있어야 하거나 영상에서 체커보드가 모두 나타나야 하는 한계점이 있었다. 이에 본 연구에서는 체커보드 중심부와 외곽부분에 각각 4개씩 8개의 블랍을 포함하는 직사각형을 이용하여 체커보드 영상의 일부만 촬영된 경우에도 자동으로 타겟점의 번호를 부여할 수 있고 별도의 입력 매개 변수 없이 자동으로 타겟을 인식하는 방법을 제안하였다. 본 연구에서 체커보드 타겟의 중심점을 자동으로 추출하기 위해서 흑백패턴의 왜곡, 경계선 변화빈도, 흑백픽셀의 비율의 3가지 조건을 이용하였다. 또한 체커보드의 방향성과 번호부여는 블랍을 이용하였다. 두 가지 타입의 체커보드에 대한 실험을 통해서 36장의 영상에 대해 1분 이내의 짧은 시간에 체커보드 타겟을 자동으로 인식할 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권8호
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• pp.2278-2291
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• 2023

Imported ornamental fish should be quarantined because they can have dangerous diseases depending on their habitat. The quarantine requires a lot of time because quarantine officers collect various information on the imported ornamental fish. Inefficient quarantine processes reduce its work efficiency and accuracy. Also, long-time quarantine causes the death of environmentally sensitive ornamental fish and huge financial losses. To improve existing quarantine systems, information on ornamental fish was collected and structured, and a server was established to develop quarantine performance support software equipped with a text search engine. However, the long names of ornamental fish in general can cause many typos and time bottlenecks when we type search words for the target fish information. Therefore, we need a technique that can correct typos. Typical typo character calibration compares input text with all characters in a calibrated candidate text dictionary. However, this approach requires computational power proportional to the number of typos, resulting in slow processing time and low calibration accuracy performance. Therefore, to improve the calibration accuracy of characters, we propose a fusion system of simple Artificial Neural Network (ANN) models and character preprocessing methods that accelerate the process by minimizing the computation of the models. We also propose a typo character generation method used for training the ANN models. Simulation results show that the proposed typo character correction system is about 6 times faster than the conventional method and has 10% higher accuracy.

• 대한토목학회논문집
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• 제28권1B호
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• pp.1-9
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• 2008

소양강댐 유역의 관측유입량과 융설 모의의 포함 유무에 따른 모의 결과를 비교함으로써 적설 및 융설 모형의 필요성을 분석하였다. 사용한 융설 모형은 Sugawara 등의 개념적 융설 모형이고, 강우-유출 모형은 NWS-PC를 사용하였다. 모형의 매개변수는 다단계 자동보정법에 의해 추정하였고, 각 단계별로 SCE-UA 알고리즘에 의해 최적화되었다. 매개변수 추정시와 검증 모의에서 RMSE, PBIAS, NSE, PME 통계량은 융설을 포함한 모의가 그렇지 않은 모의보다 좋은 결과를 나타내었다. 소양강댐의 관측유입량은 약 두 달 이상의 자기상관성을 나타내었고, 융설을 포함하지 않은 경우에 모의된 유량시계열은 20일 정도의 자기상관성을 나타내었다. 융설을 포함한 경우의 모의유량 시계열은 관측 유량시계열과 유사하게 약 두 달 이상의 자기상관성을 나타내었다. 이와 같은 결과로 소양강댐 유역의 강우-유출 모의시 적설 및 융설 모형을 포함하여야 모형의 정확성을 향상시킬 수 있다.

• Journal of the Optical Society of Korea
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• 제7권4호
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• pp.240-244
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• 2003

Simultaneous determination of concentrations for four major components in human blood serum was investigated using a Fourier-transform mid-infrared spectroscopy. Infrared spectra of human blood serum were measured in 8.404 ∼ 10.25 ${\mu}m$ range where the highest absorption peaks of glucose are located. A partial least square (PLS) algorithm was utilized to establish a calibration model for determining total protein, albumin, globulin and glucose levels which are commonly measured metabolites. The standard error of cross validation obtained from our multivariate calibration model was 0.24 g/dL for total protein, 0.15 g/dL for albumin, 0.17 g/dL for globulin, and 6.68 mg/dL for glucose, which are comparable with or meet the criteria for clinical use. The results indicate that the infrared absorption spectroscopy can be used to predict the concentrations of clinically important metabolites without going through a chemical process with a reagent.

• Radiation Oncology Journal
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• 제31권2호
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• pp.88-96
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• 2013

Purpose: This study identifies accident sequences from the past accidents in order to help the risk analysis application to the external radiotherapy. Materials and Methods: This study reviews 59 accidental cases in two retrospective safety analyses that have collected the incidents in the external radiotherapy extensively. Two accident analysis reports that accumulated past incidents are investigated to identify accident sequences including initiating events, failure of safety measures, and consequences. This study classifies the accidents by the treatments stages and sources of errors for initiating events, types of failures in the safety measures, and types of undesirable consequences and the number of affected patients. Then, the accident sequences are grouped into several categories on the basis of similarity of progression. As a result, these cases can be categorized into 14 groups of accident sequence. Results: The result indicates that risk analysis needs to pay attention to not only the planning stage, but also the calibration stage that is committed prior to the main treatment process. It also shows that human error is the largest contributor to initiating events as well as to the failure of safety measures. This study also illustrates an event tree analysis for an accident sequence initiated in the calibration. Conclusion: This study is expected to provide sights into the accident sequences for the prospective risk analysis through the review of experiences.

• 한국CDE학회논문집
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• 제20권3호
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• pp.263-268
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• 2015

Due to an increased sitting time in work, lumbar disc disease is one of the most frequent diseases in modern days, and this occasionally requires surgery for treatment. Endoscopic disc surgery, one of the common disc surgeries, requires a process of inserting a guide needle to the target disc for which the insertion path is manually planned by drawing lines on the patient's skin while monitoring the fluoroscopic view of the lumbar. Such procedure inevitably exposes both surgeon and patient to the fluoroscopy radiation emitted from the c-arm for a long time. To reduce the radiation exposure time, this study proposes a computer assisted method of calculating the 3D guide needle path by using 2D c-arm images of the disc in 3 different angles. Additionally, a method of the guide robot control based on the 3D needle path was developed by implementing the Hand-eye Calibration method to calculate the transformation matrix between the c-arm and robot base coordinate systems. The proposed system was then tested for its accuracy.

• 한국산업융합학회 논문집
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• 제17권2호
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• pp.54-60
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• 2014

The equipment of SCARA robot in processing and assembly lines has rapidly increased. In order to achieve high productivity and flexibility, it becomes very important to develop the visual feedback control system with Off-Line Programming System(OLPS). We can save much efforts and time in adjusting robots to newly defined workcells by using OLPS. A proposed visual calibration scheme is based on position-based visual feedback. The calibration program firstly generates predicted images of objects in an assumed end-effector position. The process to generate predicted images consists of projection to screen-coordinates, visible range test, and construction of simple silhouette figures. Then, camera images acquired are compared with predicted ones for updating position and orientation data. Computation of error is very simple because the scheme is based on perspective projection, which can be also expanded to experimental results. Computation time can be extremely reduced because the proposed method does not requirethe precise calculation of tree-dimensional object data and image Jacobian.

• 한국환경과학회지
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• 제21권12호
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• pp.1449-1454
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• 2012

The ion selective microelectrodes (ISME) have been applied to observe the continuous profiles of NO3-N and NH4-N in bulk solutions or biofilms. In order to evaluate the performance and applicability of ion concentration measuring system, the characteristics, such as slope of calibration curve, detection limit and potentiometric selectivity coefficient were investigated. The slopes of calibration curve showed high degree of correspondence for each target ion concentrations. And the detection limits of nitrate and ammonia ion selective microelectrode were 10-4.7 M and 10-4.4 M, respectively. These ion selective microelectrodes were proved that their own performance could be maintained for 16 days after making. NO3-N and NH4-N selective microelectrodes were also adapted to detect the continuous ion profiles of cilia media packed MLE (Modified Ludzack-Ettinger) process. And the monitored nitrate and ammonia ion profiles with the ion selective microelectrode were stable and well corresponded to the results with conventional ion chromatograph. However, the electric potential was unstable until 8 hr because of the unknown noise. The tip shape and performance of the ion selective microelectrode was stably kept over 2 days continuous monitoring.