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정동택,신동욱,김성수 한국기술교육대학교 2003 論文集 Vol.10 No.1
The high strain-rate stress-strain data at high temperature is essential for the research of high speed impact, terminal ballistics, speed forging, hot rolling, etc. However, the data for various materials is not standardized yet. SHPB(Split Hopkinson Pressure Bar)test is one of the established measuring procedures for the data. In this study, automatic high temperature(1300℃ maximum) testing system was augmented to the existing SHPB tester. Micro-p rocessor controlled testing system was designed, fabricated and tested. This can execute following procedures: (1)input and output bar arrangement, (2)specimen heating by induction heating, (3)specimen loading, (4)firing of gas gun, (5)data acquisition, and (6)quenching. The procedure from (3) to (6) is accomplished quickly, within 2 seconds, to minimize temperature variation in the specimen. The stress-strain curves of the low carbon steel based materials from room temperature to 1200℃ at strain-rate of 1000/sec were successfully obtained.
송병만,오미진,강정림,정경택,정동수 국립7개대학공동논문집간행위원회 2001 공업기술연구 Vol.1 No.-
In this paper, reflex RGB data captured from WebCam is stored to HDD through USB port at every 5 seconds intervals. Also, if strangers are detected through Motion Detection routine, warning voice message is broadcasted and invasion message is transmitted by e-mail and transmit the e-mail title to mobile phone through WAP(Wireless Application Protocol) Push. The detected image is stored to hard-disk in 'month - day - hour - minute - second . jpg' data type. And the image data is transmitted to web server through FTP(File Transfer Protocol) because invader can deletes or destroys the image data on hard-disk. We implement a surveillance system which is able to utilize through internet regardless of time and space.
정동택(Dong Teak Chung),박치영(Chi Young Park),진두한(Doo Han Jin),김태연(Tae Yeon Kim),이주연(Joo Yeon Lee),이인석(Ihnseok Rhee) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Single crystal sapphire is used for transparent bulletproof window material, but the research of dynamic behavior and fracture properties under high-speed impact has rarely been done. High speed and high resolution sequential images are required to study the interaction of the bullet with the brittle ceramic materials. This paper is about a device developed to capture the sequence of high-speed impact/penetration phenomena. This system consists of a speed measurement device, a microprocessor based camera controller, and multiple CCD cameras. By using linear array sensor, the speed-measuring device can measure a small(up to 1-2㎜ in diameter) and fast(up to Mach 3) bullet. Once a bullet is launched then it passes through the speed measurement device to register the time and the speed then the camera controller computes the exact time of arrival to the target during the flight. Then, it sends the trigger signal to the cameras and flashes with specific delay to capture the impact images sequentially. It is almost impossible to capture high speed image without estimation of the time of arrival. We were able to capture the high speed images using the new system with precise accuracy.
정동택(Dong-Teak Chung),진두한(Doo-han Jin),강형(Hyung Kang) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The nose of a missile, flying through raining region with a supersonic speed, is subjected to the rain erosion because the nose is made of a brittle ceramic material. A simple yet very effective rain erosion test method is developed. The sabot assembly similar to the hypodermic syringe carries specific amount of water is launched by a low pressure air gun. After the stopper stop the sabot assembly by impact, the steel plunger continues moving toward to squeeze the silicon rubber in front. The pressurized silicon rubber then is squeezed through the orifice in front of the sabot at high velocity, thus, accelerates the water droplet to higher velocity. The droplet velocity up to 800㎧ is successfully attained using a low pressure air gun. The ceramic specimen assembly is placed in front of the high speed water droplet and the rain erosion damage on the surface of the specimen is observed.
정동택(Dong Teak Chung),박치영(Chi Young Park),진두한(Doo Han Jin),김태연(Tae Yeon Kim),이주연(Joo Yeon Lee),이인석(Ihnseok Rhee) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.9
방탄소재로서 사파이어 재료가 대두되고 있지만 고속 충돌관련 동적거동 및 파괴특성에 관한 연구는 부족한 실정이다. 탄자와 취성세라믹재료간의 상호작용을 연구하기 위해서는 고화질의 초고속 연속영상이 필수적이다. 본 연구에서는 고속충돌 및 관통 현상을 순차적으로 촬영할 수 있는 장치를 개발하였다. 이 장치는 속도측정장치, 마이크로프로세서를 사용한 카메라 구동장치 그리고 다수의 CCD카메라로 이루어져있다. 선형배열센서를 사용한 속도측정장치는 직경 1-2 mm 탄자의 마하 3 속도를 측정할 수 있다. 발사된 탄자가 속도측정장치를 통과하면 속도와 시간이 측정되고 탄자가 비행하는 동안 카메라 구동장치가 정확한 충돌시간을 계산하여 다수의 카메라에 순차적으로 트리거 신호를 보내서 충돌전후의 형상을 순차적으로 촬영한다. 정확한 충돌시간 예측을 못하면 고해상도의 사진촬영이 거의 불가능하다. 본 연구에서 개발된 정밀 촬영장치를 사용하여 고해상도의 영상을 확보할 수 있었다. A single-crystal sapphire is used as a transparent bulletproof window material; however, few studies have investigated the dynamic behavior and fracture properties under high-speed impact. High-speed and high-resolution sequential images are required to study the interaction of the bullet with the brittle ceramic materials. In this study, a device is developed to capture the sequence of high-speed impact/penetration phenomena. This system consists of a speed measurement device, a microprocessor-based camera controller, and multiple CCD cameras. By using a linear array sensor, the speed-measuring device can measure a small (diameter: up to 1- 2 mm) and fast (speed: up to Mach 3) bullet. Once a bullet is launched, it passes through the speed measurement device where its time and speed is recorded, and then, the camera controller computes the exact time of arrival to the target during flight. Then, it sends the trigger signal to the cameras and flashes with a specific delay to capture the impact images sequentially. It is almost impossible to capture high-speed images without the estimation of the time of arrival. We were able to capture high-speed images using the new system with precise accuracy.
성인에서 회장말단의 원발성 림프종에 의한 장중첩증 경험
정금오(Gum Oh Chung),강동백(Dong Baek Kang),오정택(Jung Teak Oh),조향정(Hyang Jeong Jo) 대한외과학회 2007 Annals of Surgical Treatment and Research(ASRT) Vol.72 No.3
Most intussusceptions occur in children and no etiologic factor can be determined in most cases. In contrast, adult intussusception is rare and many cases in adults are generally related to neoplasm such as lymphoma, carcinoid tumor, malignant tumor, sarcoma, benign tumor and congenital abnormalities. Intussusception in adults that’s due to primary malignant lymphoma of the terminal ileum is a rare clinical condition. We describe here two cases of ileocolonic-type intussusception that were due to primary malignant lymphoma of the terminal ileum. The clinical, radiographic and pathologic finding are described along with a brief review of the literature.
진두한(Doo Han Jin),정동택(Dong Teak Chung),박치영(Chi Young Park),이인석(Ihnseok Rhee) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
A mini ball acceleration system was developed for the study of dynamic fracture of ceramic and single crystal materials. This system consists of (1) low pressure gas gun, (2) sabot assembly, (3) stopper block with plastic membrane for second acceleration, (4) velocity measurement device for sabot and ball, and (5) enclosed target box. The plastic sabot assembly houses steel plunger and the void filled with silicone rubber. The sabot is stopped by the stopper block then the steel plunger inside the sabot compress the silicone rubber to high pressure to rupture the plastic membrane. Then the compressive energy of the silicone rubber is transferred to the ball. More than ten times of initial speed was attained. Non-contact velocity measurement system is measuring the supersonic speed of the mini ball. Maximum speed up to 1200m/s for plastic and 700m/s for steel ball was attained. Perforation test of glass window was successfully done by the developed impact system.