• Journal of the Korean Society of Radiology
• /
• v.16 no.2
• /
• pp.151-156
• /
• 2022

A detector using a small number of photosensors was designed, and the position of a scintillation pixel that interacted with gamma rays through a maximum likelihood position estimation(MLPE) was measured as a digital position. For this purpose, simulation was performed using DETECT2000, which can simulate the movement of light within the scintillator, and the accuracy of position measurement was evaluated. A detector was configured using a 6 × 6 scintillation pixel array and 4 photosensors, and a gamma ray event was generated at the center of each scintillation pixel to create a look-up table through the ratio of acquired light. The gamma-ray event generated at the new position was applied as the input value of the MLPE, and the positiion of the scintillation pixel was converted into a digital positiion after comparison with the look-up table. All scintillation pixels were evaluated, and as a result, a high accuracy of 99.1% was obtained. When this method is applied to the currently usesd system, it is concidered that the process of determining the position of the scintillation pixel will be simplified.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.16 no.1
• /
• pp.81-91
• /
• 1986

The author obtained the trans cranial radiographs of right and left side and the individualized lateral tomograms of right and left side after the analysis of submental vertex view from 8 young adults of 25-32 years with normal occlusion. The condylar position from 32 radiographs of normal TMJs were assessed with each measurement methods. All datas from these analyses were recorded and statistically processed with CYBER computer system. The results were obtained as follows. 1. In each measurement methods, the area measurements using the midpoint fossa and the midpoint condyle revealed the hightest concordance rate between the radiographic pairs. 2. In the subjective evaluation, the qualitative concordance existed in 44% and the full concordance existed in 25%, so it was found that concordance rates were relatively low between the radiographic pairs. 3. In each measurement methods, the area measurement using the midpoint fossa revealed the strongest correlation between the radiographic pairs. 4. The correlations between the area measurement using the midpoint fossa and subjective valuation revealed relatively strong value which is 0.926 in the trans cranial radiographic series and the lowest value which is 0.743 in the tomographic series.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.473-478
• /
• 2003

This paper presents static and dynamic measurement of the stress and motion characteristics for crawler type excavators. Eight scenarios were prepared for static measurement based on two extreme digging positions, maximum digging reach position and maximum digging force position. The measured items for static motion included stress, cylinder pressure, cylinder stroke and digging force. The measured static stresses showed that asymmetric digging force acting on a bucket induced higher stress level than symmetric one. The measured static pressures and digging forces also agreed with design pressures and design digging forces, respectively. The dynamic measurement was performed for two types of motion, that is, simple reciprocation of each cylinder and actual digging motion. The measured items for dynamic motion were stroke and pressure of each cylinder, stresses on the working device and acceleration on the upper plate of an arm. The measured data showed that the natural frequency of the excavator highly depended on the hydraulic stiffness of cylinders. Digging motion tests revealed that digging motion was closer to static motion rather than dynamic one.

• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.2
• /
• pp.202-205
• /
• 2010

When we render 3D sound images using headphones or speakers, the main key of this technology is the Head-related transfer function (HRTF) database. Even though there are various HRTF databases, they have some drawbacks such as detrimental effects caused by imperfect measuring environment and insufficient measurement points. Moreover there is no database with Korean subjects. We are planning to develop the HRTF database for Korean. As a first step to establish the HRTF database aimed at Korean, the new HRTF measurement system with minimized aforementioned drawbacks is designed. In this paper, the newly designed HRTF measurement system is introduced and the overall effects caused by the diffraction of the apparatus, especially the headrest and backrest of the chair, are analyzed. The backrest of the chair does not distort the HRTFs significantly while the headrest makes significant distortion on the HRTFs and it could have significant effects on directional perception. We determined acceptable head rotation angle and head position of the subject for accurate HRTF measurement based on the experiments with B&K HATS. We conclude that the 3 degrees of the head rotation and the 1.5cm front/back/left/right shift of the head do not distort the HRTFs significantly.

• Journal of Korea Multimedia Society
• /
• v.16 no.8
• /
• pp.934-942
• /
• 2013

Image scaling is used for a variety of real-life applications. In order to evaluate the performance of transform functions, the image quality are compared together before and after processing. For the objective evaluation of the transform functions, the exact criterion of image quality is required, and various aspects approaches are practically performed. However, few researches have been conducted on image quality measurement considering the position of pixels that are skipped or newly generated in the process of the image scaling. Therefore this paper focuses on the objective image quality measurement for positions of skipped or estimated pixels in the image scaling. The proposed method generated new image quality measure considering the positional changes using a conventional measure and evaluated sensitivity about positional changes. Through this experiments, it is observed that conventional image quality measurement is definitely affected by positional changes of a skipped and estimated pixels. It is also confirmed that the proposed method is an objective criterion to represent image quality for positional changes of skipped or estimated pixels. The proposed method can be used as a criterion to evaluate the performance of image restoration or enhancement functions.

• Transactions of Materials Processing
• /
• v.13 no.3
• /
• pp.273-278
• /
• 2004

This paper subscribes the measurement system that can position the target to measure by moving 2-axis stage, which is controlled by the data from image processing technique. The high resolution camera and lens are used in measurement of micro mechanical part, but the region of measurement is very small. It is necessary the re-positioning to measure several regions in one part. The system described in this paper has the accuracy with about $0.9\mu\textrm{m}$ resolution per one pixel and can be applied to measure micro mechanical part.

• Journal of the Korean Society of Industry Convergence
• /
• v.21 no.2
• /
• pp.63-70
• /
• 2018

In this paper, the design of a novel 6-axis compliance device with force/torque sensing capability and the experiment results on force measurement are presented. Unlike the traditional control methods using a force/torque sensor with very limited compliance, the force control method employs a compliant device to provide sufficient compliance between an industrial robot and a rigid environment for more stable force control. The proposed compliance device is designed to have a diagonal stiffness matrix at the tip and uses strain gauge measurement which is robust to dust and oil. The measurement circuit is designed with low-cost IC chips however the force resolution is 0.04N.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.6
• /
• pp.128-135
• /
• 1996

This paper proposes a high precision measurement technique to obtain the height of gage block with a few millimeter height. The proposed technique is consisted of two steps : In the first step, laser position transducer and electric micrometer are adopted to obtain a coarse value of the height of gage block, and then, in the second step, heterodyne laser interferometry is adopted to acquire the precision value. A new kind of phase detector is constructed in the low cost for the heterodyne interferometer and its linearity with ${\pm}1%$ is confirmed by experiment. Also measurement error factors due to enviroments are discussed and methodology to reduce such errors is proposed. Preliminary experiments are carried out for the gage blocks of as high as a few millimeter.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.273-274
• /
• 2006

Fundamental research is conducted in order to develop measurement system for E-beam focus position compensation. In this paper, simulation results using Fresnel's formula shows effect of photoresist film thickness according to incident conditions. Also, electromagnetic simulator is developed based on Boundary Element method (BEM) and several results confirm the feasibility of the simulator.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.11a
• /
• pp.733-737
• /
• 1996

This paper presents a method to measure tile position and orientation of a prismatic polyhedral object (of unknown width, length, height, and number of vertices) using machine vision. The width, length, and origin of workplace where an object is lying are defined as Preliminary operation. The edges of an object are detected from captured image using least sum of square error. The information of an object is determined from the geometric relationships between edges. As an user interface, a versatile image processing program is developed in several modules, and renders a very useful 3D measurement at a limited constraints when adopted in automation of production process. The flexibility of camera position from the algorithm developrf can be used for automated pick and place operations and feeding workpiece u: ;ing assembly robot.