균일가열법으로 제조한 반용융 A390합금의 미세조직 및 성형성

임수근,윤병은,장동훈,엄정필,김득규 慶尙大學校生産技術硏究所 1997 生産技術硏究所論文集 Vol.13 No.-

Microstructure of hypereutectic Al-17wt.% Si alloy, fabricated by mechanical stirring and by reheating at semi-solid state, was investigated by optical microscope. Flow behavior semi-solid metal also was investigated at diffentent mould temperatures 280℃, 290℃ and 300℃ . Size of silicon particles were increased over 100㎛ durig solidification as a result of stirring. It is considered as microstructural coarsening by bonding between neighbouring primary silicon particles during stirring of slurry. In case of reheating at semi-state, however, primary silicon particle was not increased at size of 40㎛ and nearly spherical aluminum solde particle also was improved when solid fraction was 0.7 at mould temperature of 300℃ than other conditions.

냉각판을 이용한 반응고 A356합금의 미세조직

임수근,윤병은,장동훈,엄정필,김득규 慶尙大學校生産技術硏究所 1997 生産技術硏究所論文集 Vol.13 No.-

In this study, microstructure, size of primary α, solid fraction and hardness of A356 Al alloy were investigated. Semi-solid A356 alloys were obtained by semi-solid continuous casting apparatus consists of melting furnace, formation apparatus of granular primary α and continuous casting apparatus. Size of primary α and solid fraction were decreased with decreasing temperature, and with increasing volume of cooling water. At the cooling water temperature of 15℃ and cooling water volume of 18.2ℓ/min, the sizes of primary α phases were decreased up to 40㎛, and fraction solid was 0.68.

교내 커피전문점 소비에 대한 중요도·실행도 분석: - 충북대학교 사례를 중심으로 -

배재원, 장동건, 유도일 忠北大學校 農業科學硏究所 2017 農業科學硏究 Vol.33 No.1

This study investigates students’ use conditions in- and out-of- school coffee shops, and analyzes the importance and the performance for students’ consumption behaviors for those coffee shops. For this study, we apply Importance-Performance Analysis (IPA) by carrying out a survey targeting students at the Chungbuk National University. IPA results categorize various factors with respect to levels of the importance and the performance, respectively.

충남 서북부지역 여성의 질세포진 검사에 대한 임상적 고찰

이석민,선우재근,장경택,서수형,김민관,배동한 순천향의학연구소 1996 Journal of Soonchunhyang Medical Science Vol.2 No.2

Pap smear were performed to 30,294 women living in the north-west of Chung-nam. The result are summarized below 1. Positive vaginal cytology was 1.09 percent. 2. 72 percents women in their 30's and 40's experienced vaginal cytology. 3. Vaginal cytology was performed at a decreasing rate as age increases. 4. Positive cytology rate is 2.42% higher than average for elderly women over the age of 65. The present date indicates that pap smear is being widely recognized to be important but they needs to be continued advocacy for pap smear.

3D 온라인 슈팅 게임 개발 : "3D 포트리스"

金敬植,崔勝寬,寓昔珍,申一卿,朴勝浩,李東熙,李東建,張孝善 호서대학교 공업기술연구소 2000 工業技術硏究所論文集 Vol.19 No.-

In this paper, features and efficiencies of the 3D engine are described which has been developed through the research of 3D real time rendering techniques. And an on-line shooting game "3D Fortress" which has been developed using this 3D engine with server technologies is introduced for the techniques and methodology applied in the process of development of the game as well as the features and discussions of its implementation.

New Korean Ginseng Cultivar ‘Cheonmyeong’ with High Yield and Rusty Root Tolerance

Jang-Uk Kim,Young-Chang Kim,Dong-Hwi Kim,Jung-Woo Lee,Kyong-Hwan Bang,Dong-Yun Hyun,Myeong-Hwan Jang,Bong-Jae Seong,Gun-Hwan Park,Ye-ji Yoon,Ick-Hyun Jo 한국원예학회 2021 원예과학기술지 Vol.39 No.1

In 2008, a new Panax ginseng (ginseng) cultivar, ‘Cheonmyeong’, was bred by pure-line selection for tolerance to physiological disorders using a genetic resource collected from the farm race field, Buyeo, Chungnam, Korea. In 2019, ‘Cheonmyeong’ was registered as a new breed by the Korea Seed and Varieties Service (grant number 7467) and accorded plant breeders’ rights. ‘Cheonmyeong’ has a yellowish orange pericarp, which has not been previously reported. ‘Cheonmyeong’ sprouted and flowered 2 days earlier than the control cultivar ‘Chunpoong’, and its fruit-ripening period occurred 3 days earlier. ‘Cheonmyeong’ had 1.5-fold more stems per plant than ‘Chunpoong’. ‘Cheonmyeong’ plants were characterized by a lower occurrence of rusty root disease, and had approximately 28% higher 4-year-old root yields (571.8 ± 99.7 kg·10a<SUP>-1</SUP>) than those of the rusty root-tolerant ‘Chunpoong’ (444.1 ± 110.4 kg·10a<SUP>-1</SUP>). The total ginsenoside content of ‘Cheonmyeong’ (31.70 ± 1.83 mg·g<SUP>-1</SUP>) was higher than that of ‘Chunpoong’ (26.62 ± 1.60 mg·g<SUP>-1</SUP>). Concentrations of the ginsenosides Rg1 (which improves human memory and learning), Rf (which is effective for neuronal oscillation), and Rc (which has anti-inflammatory and analgesic effects) were higher in ‘Cheonmyeong’ than in ‘Chunpoong’. ‘Cheonmyeong’ is likely to have strong tolerance against physiological disorders, ensuring reliable production of ginseng, even in response to changes in the cultivation environment.

Radiological Characteristics of the Havar Foil in the Cyclotron Target

Dong gun Jang,Sang hwa Shin,Chang lak Kim,Gyeong hyeon Gwak2 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

The cyclotron is an apparatus used for the production of radioactive isotopes through nuclear reactions, resulting in the inevitable emission of neutrons. Consequently, surrounding components become activated. The purpose of this study was to investigate the radiological characteristics of Havar foil, a periodic replacement part of the Targetry system. In this study, radioactivity and radiation dose were calculated based on the time of Havar foil replacement and equipment dismantling. The time to dismantle the equipment was set at one year after the equipment was shut down, based on the recently used 1g of Havar foil. All simulations were performed using the FLUKA program. First, in the simulation results, 11 elements (Re, W, Tc, Nb, Cu, Ni, Co, Fe, Mn, Cr, V) were converted into 36 radioisotopes by activation based on the replacement period. Based on radioactivity levels, major isotopes included 52Mn (77.63%), 56Co (13.36%), 96Tc (2.4%), and 95Tc (1.80%). Based on radiation dose rates, 52Mn (82.66%) and 56Co (13.45%) exhibited the highest levels. Furthermore, the dose rates at distances of 10 cm, 50 cm, and 100 cm were found to be 1.36E+1 mSv/hr, 2.24E+00 mSv/hr, and 8.80E-01 mSv/hr, respectively. Second, as of the time the equipment was dismantled, 20 radioactive isotopes of 10 elements, excluding short-lived nuclides, were generated. In terms of radioactivity, 56Co (45.83%), 55Fe (19.73%), 57Co (14.48%), and 54Mn (13.50%) were prominent. Regarding radiation dose rates, 56Co (92%) and 54Mn (7.32%) exhibited higher levels. Dose rates at distances of 10 cm, 50 cm, and 100 cm were calculated at 5.31E-01 mSv/hr, 8.80E-02 mSv/hr, and 3.47 E-02 mSv/hr, respectively. Third, according to the radioactive waste classification standards in the replacement and decommissioning stages, Havar foil was predicted to be low-level radioactive waste in terms of radioactivity. In addition, it was derived that a cooling period of approximately 12 years is necessary to satisfy the allowable dose for clearance level waste. In conclusion, Havar foil, which is periodically generated as radioactive waste, can cause radiation exposure to replacement workers. Therefore, special and careful management is required for the Havar foil of the cyclotron.

다인병실에서 이용되는 방사선원의 종류에 따른 공간선량률 분석

장동근(Dong-Gun Jang),김정훈(Junghoon Kim),박은태(Eun-Tae Park) 대한방사선과학회(구 대한방사선기술학회) 2017 방사선기술과학 Vol.40 No.3

의료 방사선은 환자의 진단 및 치료를 함에 있어 중대한 이득을 제공하지만 주변인에게 불필요한 피폭을 발생시킨다. 이에 본 연구에서는 환자와 일반인이 같은 공간 내 상주하는 다인 병실에 대해 선원항의 종류에 따른 공간선량률을 분석하고자 하였다. 실험은 몬테카를로 모의모사(MCNPX)를 이용하였으며, 선원항은 전신 뼈검사 환자와 이동형 X선 발생장치를 모사하였다. 실험결과 전신 뼈검사 환자의 측면 병상 위치에서 약 3.46 μSv/hr의 선량이 나타났으며, 이동형 X선 발생장치를 이용한 실험 결과, 흉부검사 시 측면 병상 위치에서 1.47 × 10 -8 μSv/irradiation, 복부검사 시 측면 병상 위치에서 2.97 × 10 -8 μSv /irradiation 값이 나타났다. 이처럼 다인병실에서는 주변 환자에게 불필요한 방사선을 발생시키며, 국내의 미흡한 다인 병실의 방사선에 대한 법적인 규제 및 체계적인 차폐 방안이 마련되어져야 할 것이다. Medical radiation offers significant benefits in diagnosing and treating patients, but it also generates un-necessary radiation exposure to those nearby. Accordingly, the objective of the present study was to ana-lyze spatial dose rate according to types of radiation source term in multi-bed hospital rooms occupied by patients and general public. MCNPX was used for geometric simulation of multi-bed hospital rooms and radiation source terms, while the radiation source terms were established as whole body bone scan patients and imaging using a portable X-ray generator. The results of simulation on whole body bone scan patients showed 3.46 μSv/hr to another patient po-sition, while experimental results on imaging using a portable X-ray generator showed 1.47 × 10 -8 μSv/ir-radiation to another patient position in chest imaging and 2.97 × 10 -8 μSv/irradiation to another patient position in abdomen imaging. Multi-bed hospital room, unnecessary radiation generated in the surrounding patients, while legal regu-lations and systematic measures are needed for radiation exposure in multi-bed hospital rooms that are currently lacking in Korea.

몬테카를로 모의 모사를 이용한 방사성옥소 2인 치료병실의 안전성 평가

장동근(Dong Gun Jang),고성진(Sung Jin Ko),김창수(Chang Soo Kim),김정훈(Jung Hoon Kim) 대한방사선과학회(구 대한방사선기술학회) 2016 방사선기술과학 Vol.39 No.4

방사성옥소를 이용한 2인 치료격리병실은 환자간의 불필요한 피폭선량을 유발하게 된다. 이에 본 연구에서는 방사성 옥소를 섭취 후 배설 없이 모두 인체에 분포하였다는 가정 하에 방사성 옥소의 물리적 특성 및 생물역동학적 정보를 제외한 보수적인 관점으로 몬테카를로 모의 모사를 이용한 2인 치료격리병실의 안전성을 평가하고자 한다. 실험 결과 방사성옥소에서 방출되는 364 keV의 감마선은 공기층 약 30 cm 또는 납 차폐체 3 mm가 반가층으로 작용됨을 파악할 수 있었으며, 환자간 거리 및 납 차폐체의 두께를 이용하였을 때, 입원기간(48시간)동안 상대방 환자로부터 받게 되는 외부 피폭선량은 5 mSv 이하로 법적 격리 기준선량 보다 낮게 나타남으로써 2인 치료격리병실의 효율적인 관리가 가능한 것으로 분석되었다. Radioactive iodine treatment that uses the 2 people isolation room is to cause unnecessary radiation exposure between patients. This research is to be tested safety of 2 people Isolation treatment room and dose-rate through conservative perspective except physiology characteristic and biology information on the assumption that patient have iodine without excretion in 2 people isolation treatment room. This research shows that 364 keV gamma rays emitted by the radioiodine was to determine that the air layer about 30 cm or lead shield 3 mm a half-layer. In addition, In addition, patients in the distance, and lead shielding, length of hospital stay (48 hours) for external radiation exposure that is received from the other patients, two of treatment as appears to be lower than the legal isolation standard dose less than 5 mSv isolation room effective analyzed that manageable.

감마선 에너지에 따른 납치마의 차폐효과 분석

장동근(Dong-Gun Jang),이상호(Sang-Ho Lee),최형석(Hyung-Seok Choi),손주철(Joo-Chul Son),윤창용(Chang-Yong Yoon),지영식(Yung-Sik Ji),조용인(Yong-In Cho),이홍제(Hong je Lee),양승오(Seoung-Oh Yang) 대한방사선과학회(구 대한방사선기술학회) 2014 방사선기술과학 Vol.37 No.4

의료기관에서 사용되고 있는 전자파 방사선은 매우 다양한 에너지를 사용하고 있으며 연구자에 따라 고에너지의 전자파 방사선이 납치마와 상호작용을 한 후 차폐효과를 얻을 수 있다는 의견과 차폐가 효과가 없을 뿐만 아니라 오히려 피폭을 가중 시킨다는 상반된 의견이 제시되고 있다. 이에 본 연구에서는 몬테칼로 모사를 이용하여 전자파 방사선의 에너지에 따른 납치마의 차폐효과를 분석하고자 하였다. 몬테칼로 모사를 이용하여 전자파 방사선을 10 keV부터 500 keV까지 10 keV 단위로 1 MBq 방출시켜 납 차폐체의 유무에 따른 선량차이를 차폐율로 표현한 결과 납차폐체(0.25 mmPb)를 사용하여 차폐를 실시하였을 때 고에너지 전자파 방사선에서 차폐율이 현저히 떨어져 차폐시 오히려 선량이 증가됨을 알 수 있었다. The medical institution has been used electromagnetic radiation of various energy. But researchers are divided on whether using apron for radiation shielding will be effective or not. The purpose of present study was to analyze electromagnetic radiation shielding effect of apron by us-ing Monte carlo simulation. 1 MBq electromagnetic radiation was emitted from 10-500 keV at 10 keV increments in Monte carlo simulation. Then shielded radiation dose difference was confirmed, when 0.25 mmPb shield use for shielding. As a results, shielding ratio was markedly decreased in high energy electromagnetic radiation. The radia-tion dose was inversely increased with 0.25 mmPb shielding.