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정하규,권원태,이수일 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-
Thermosonic bonding is a technology using heat and ultrasonic for the electronic packaging. Mechanical properties and alignment of the horn have a great effect on the bonding capability of the thermosonic bonding system. In this research, the effect of tolerance parameters and alignment to the performance of the bonding system are studied. The tolerance parameters and alignment that give most significant the effect on the performance of the bonding system are determined using Taguchi's method. It is found that error of the length of horn is determined to be the parameter that have great effect on the performance of the system.
정하규,김동현,정해조,손혜경,홍순일,윤미진,이종두,김희중 한국의학물리학회 2002 의학물리 Vol.13 No.3
The measured attenuation correction with transmission (Tx) scans produced quantitatively accurate images. However, it was not clear for optimal emission (Ex) and Tx scan time in PET imaging. This study was to evaluate acceptable Ex and Tx scan time by simulating clinical situations using various phantoms. Cylindrical and NEMA phantom were used for $^{18}$ F-PET scan using 2D protocol in GE Advance PETTM scanner. Cylindrical phantom was filled with 136 MBq 18F, and five regions of interests (ROI) were drawn on 23 slices. NEMA phantom had three inserts containing water, air and polytetrafluoro-ethylene (PTFE). Outside of these inserts were filled with 309 MBq of $^{18}$ F, and total 12 ROIs were drawn on 23 slices. Scans were carried out according to five Ex scan times: 2, 5, 10, 15, and 30 min, and nine Tx scan times: 2, 3, 4, 5, 7, 10, 15, 20, and 30 min. Images were reconstructed using measured attenuation correction, and ROI analyses were performed for all images, and mean, standard deviation (SD), coefficient of variation and percent errors were calculated. For cylindrical phantom study, ROI mean and SD were decreased as Ex and Tx time increased. Coefficients of variation were kept constant, when Tx was greater than 10 min. The amount of error decreased for the increment of Ex time from 10 min to 15 min was almost the same to that from 15 min to 30 min. In NEMA phantom Tx 15 min showed the lowest er개r level when the percent errors for three inserts were summed for all of the Ex times. This study suggested that Ex 15 min and Tx 15 min were acceptable as optimal scan time for the scanning protocol and the dose of radiopharmaceuticals used in these phantom study.
SAR 영상을 활용한 저수지 수표면적 탐지 알고리즘 비교 연구
정하규,박종수,이달근,이준우,Jeong, Hagyu,Park, Jongsoo,Lee, Dalgeun,Lee, Junwoo 대한원격탐사학회 2022 大韓遠隔探査學會誌 Vol.38 No.6
The reservoir is a major water supply source in the domestic agricultural environment, and the monitoring of water storage of reservoirs is important for the utilization and management of agricultural water resource. Remote sensing via satellite imagery can be an effective method for regular monitoring of widely distributed objects such as reservoirs, and in this study, image classification and image segmentation algorithms are applied to Sentinel-1 Synthetic Aperture Radar (SAR) imagery for water body detection in 53 reservoirs in South Korea. Six algorithms are used: Neural Network (NN), Support Vector Machine (SVM), Random Forest (RF), Otsu, Watershed (WS), and Chan-Vese (CV), and the results of water body detection are evaluated with in-situ images taken by drones. The correlations between the in-situ water surface area and detected water surface area from each algorithm are NN 0.9941, SVM 0.9942, RF 0.9940, Otsu 0.9922, WS 0.9709, and CV 0.9736, and the larger the scale of reservoir, the higher the linear correlation was. WS showed low recall due to the undetected water bodies, and NN, SVM, and RF showed low precision due to over-detection. For water body detection through SAR imagery, we found that aquatic plants and artificial structures can be the error factors causing undetection of water body.
정하규,권원태,리광훈,심현석,정종혁,이현욱 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-
Thermosonic bonding is a method using heat and ultrasonic for bonding two materials. Since a horn transfers vibration and heat to the bonding material, it is a very important to figure out the heat flow on the horn and the alteration of the dynamic behavior due to the manufacturing error of the horn. In this research, the effect of temperature to the horn system and the effect of tolerance parameters to the amplitude and orientation of the system are performed. The manufacturing error that give most significant the effect on the amplitude and orientation are determined using Taguchi's method. It is found that the durability of the horn is affected by the temperature, while the amplitude and the orientation by the error of the length.
횡 방향 플립 칩 초음파 접합 시 혼의 공차변수가 시스템의 진동에 미치는 영향
정하규(Ha Kyu Jung),권원태(Won Tae Kwon),윤병옥(Byung Ok Yoon) 한국생산제조학회 2009 한국생산제조학회지 Vol.18 No.1
Thermosonic flip chip bonding is an important technology for the electronic packaging due to its simplicity, cost effectiveness and clean and dry process. Mechanical properties of the horn and the shank, such as the natural frequency and the amplitude, have a great effect on the bonding capability of the transverse flip chip bonding system. In this research, two kinds of study are performed. The first is the new design of the clamp and the second is the effect of tolerance parameters to the performance of the system. The clamp with a bent shape is newly designed to hold the nodal point of the flip chip. The second is the effect of the design parameters on the vibration amplitude and planarity at the end of the shank. The variation of the tolerance parameters changes the amplitude and the frequency of the vibration of the shank. They, in turn, have an effect on the quantity of the plastic deformation of the gold ball bump, which determined the quality of the flip chip bonding. The tolerance parameters that give the great effect on the amplitude of the shank are determined using Taguchi’s method. Error of set-up angle, the length and diameter of horn and error of the length of the shank are determined to be the parameters that have great effect on the amplitude of the system.
GE AdvanceTM 양전자방출단층촬영기의 표준 성능평가
정하규(Ha Kyu Jeong),김희중(Hee Joung Kim),손혜경(Hye Kyung Son),봉정균(Jung Kyun Bong),정해조(Hai Jo Jung),전태주(Tae Joo Jeon),김재삼(Jae Sam Kim),이종두(Jong Doo Lee),유형식(Hyung Sik Yoo) 대한핵의학회 2001 핵의학 분자영상 Vol.35 No.2
N/A Purpose: The purpose of this study was to establish optimal imaging acquisition conditions for the GE AdvanceTM PET imaging system by performing the acceptance tests designed by National Electrical Manufacturers Association (NEMA) protocol and General Electric Medical Systems (GEMS) test procedures. Materials and Methods: Performance tests were carried out with 18FDG radioactivity source and phantoms by using a standard acquisition mode. Transaxial resolution and scatter fraction tests were performed with a line source and axial resolution with a point source, respectively. A cylindrical phantom made of polymethylmethacrylate (PMMA) was used to measure sensitivity, count rate losses and randoms, uniformity correction, and attenuation inserts were added to measure remaining tests. The test results were acquired in a diagnostic acquisition mode and analyzed mainly on high sensitivity mode. Results: Transaxial resolution and axial resolution were measured as average of 4.65 mm and 3.98 mm at 0 cm, and 6.02 mm and 6.71 mm at 20 cm on high sensitivity mode, respectively. Average scatter fraction was 9.87%, and sensitivity was 225.8 kcps/ Ci/cc of trues. Activity at 50% deadtime was 4.6 Ci/cc, and the error of count rate correction at that activity was from 1.49% to 3.83%. Average nonuniformity for total slice was 8.37%. The accuracy of scatter correction was -0.95%. The accuracies of attenuation correction were 5.68% for air, 0.04% for water and -6.51% for polytetrafluoroethylene (PTFE). Conclusion: The results satisfied most acceptance criteria, indicating that the GE AdvanceTM PET system can be optimally used for clinical applications. (Korean J Nucl Med 2001;35:100-112)