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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.
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.
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.
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 ( Hague Chung ),이희준 ( Lee Heejun ),강정호 ( Jungho Kang ),전문석 ( Moon-soeg Jun ) 한국정보처리학회 2016 한국정보처리학회 학술대회논문집 Vol.23 No.1
정보통신의 발달로 인하여 사물간의 필요한 모든 정보를 상호작용하는 IoT(Internet of Thing)환경이 발전하고 있다. 홈 IoT환경에서는 스마트폰 어플리케이션을 통하여 집안 내부를 살펴보고 외부 침입자가 들어오면 이를 감지, 신고할 수 있는 IP Camera의 수요가 증가되고 있다. 그러나 IP Camera의 해킹 사례가 증가 하고 있고 취약한 인증, 잠재적인 공격 가능성 등 보안문제가 발견되었다. 이에 본 논문에서는 대중적으로 많이 사용되고 있는 IP Camera와 Smart Phone과의 안전한 사용자 인증 프로토콜을 제안하였다.
안전한 오픈소스 소프트웨어를 위한 침해여부 판정 모듈연구
정하규 ( Hague Chung ),박근일 ( Geunil Park ),전문석 ( Moon-soeg Jun ) 한국정보처리학회 2016 한국정보처리학회 학술대회논문집 Vol.23 No.2
최근 IT 제품의 발달로 무선화, 지능화 등 다양한 분야에서 소프트웨어 활용이 증가하고 있으며, 이에 따라 오픈소스 소프트웨어의 사용이 증가되고 있다. 하지만 공개 오픈소스 소프트웨어는 악의적인 문제 발생 시 일일이 조사, 발견해 낼 수 없는 단점이 있다. 본 논문에서는 안전한 소프트웨어 개발을 위해 정적/동적 취약적 분석을 활용한 취약점 침해여부 판전 모듈 설계를 제안하였다.