• Nuclear Engineering and Technology
• /
• 제51권5호
• /
• pp.1406-1416
• /
• 2019

In this research, a multi-slit prompt-gamma camera was developed to locate the distal dose falloff of the proton beam spots in spot scanning proton therapy. To see the performance of the developed camera, therapeutic proton beams were delivered to a solid plate phantom and then the prompt gammas from the phantom were measured using the camera. Our results show that the camera locates the 90% distal dose falloff (= d90%), within about 2-3 mm of error for the spots which are composed $3.8{\times}10^8$ protons or more. The measured location of d90% is not very sensitive to the irradiation depth of the proton beam (i.e., the depth of proton beam from the phantom surface toward which the camera is located). Considering the number of protons per spot for the most distal spots in typical treatment cases (i.e., 2 Gy dose divided in 2 fields), the camera can locate d90% only for a fraction of the spots depending on the treatment cases. However, the information of those spots is still valuable in that, in the multi-slit prompt-gamma camera, the distal dose falloff of the spots is located solely based on prompt gamma measurement, i.e., not referring to Monte Carlo simulation.

• Nuclear Engineering and Technology
• /
• 제54권2호
• /
• pp.437-441
• /
• 2022

In this study, we developed a neutron time-of-flight (nTOF) measurement system for a 1.7-MV tandem proton accelerator with a target covered with 300-nm-thick lithium (Li) layer. With implementation of beam chopping module after its ion source, the accelerator is configured to operate in pulsed-beam mode with a pulse width <50 ns at 20-kHz repetition rate. This enables the gamma flash-type nTOF measurement system to identify the neutron generated with 3-MeV proton beam energy. The nTOF system consists of a 30" cylindrical NaI(Tl) and four stilbene scintillation detectors. The NaI(Tl) scintillator is placed 50 cm from the Li target to measure the time of beam irradiation on the target, and the stilbene detectors are placed 2 and 2.4 m away to measure nTOF at each location. The nTOF system successfully measured the generated neutron energy at irradiated proton energies of 2.6 and 3.0 MeV with an average energy resolution of 15%.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
• /
• pp.271-275
• /
• 2004

A fast switching thyristor with a superior trade-off property between the on-state voltage drop and the turn-off time could be fabricated by the proton irradiation method. After fabricating symmetric thyristor dies with a voltage rating of 1,600V from $350{\mu}m$ thickness of $60{\Omega}cm$ NTD-Si wafer and $200{\mu}m$ width of N-base drift layer, the local carrier lifetime control by the proton irradiation was performed with help of the HI-13 tandem accelerator in China. The thyristor samples irradiated with 4.7MeV proton beam showed a superior trade-off relationship of $V_{TM}=1.55V\;and\;t_q=15{\mu}s$ attributed to a very narrow layer of short carrier lifetime(${\sim}1{\mu}s$) in the middle of its N-base drift region. To explain the small increase of $V_{TM}$, we will introduce the effect of carrier compensation by the diffusion current at the low carrier lifetime region.

• 생명과학회지
• /
• 제17권8호통권88호
• /
• pp.1100-1103
• /
• 2007

합성항산화제 3종과 17종의 식물 추출물을 이용하여 양성자 빔을 1,000, 5,000, 10,000 Gray 수준으로 처리하여 에너지양에 따른 항산화 활성에 미치는 영향을 탐색 하고자 DPPH radical 소거능 과 ABTS cation radical 소거능의 활성에 대하여 조사하였다. 이중 6종류의 시료는 양성자 빔을 조사한 결과 활성이 감소하였으며, 2종류의 시료는 활성변화가 없었으며, 12종류의 시료는 활성이 증가하였다. DPPH radical 소거 효과는 1,000 Gray 에서 마황은 60%, 괄루인은 5,000 Gray 에서 77.8%로 활성이 증가하는 경향을 나타내었다. ABTS cation radical 소거효과에서 토천궁은 1,000 Gray의 양성자 빔을 조사한 결과 38.5% 활성이 감소하였으며, 합성 항산화제는 활성변화가 거의 없으나, 뼝쑥 추출물은 5,000 Gray에서 $IC_{50}$값이 2.4 ${\mu}g/ml$로 BHT의 $IC_{50}$값 2.3 ${\mu}g/ml$과 유사하였다.

• 열처리공학회지
• /
• 제32권1호
• /
• pp.29-35
• /
• 2019

The remedial junction is found in the network of single walled carbon nanotubes after the irradiation of protons not only for the better mechanical strength but also for the higher property of electrical conductivity. The irradiated proton formed a beam transferred sufficient energy to change the sp2 structure of atomic carbon as much as damage of crystalline formation, however it is shown the cross bonding while recovery of structure. This improved network in 2-D atomic chain of carbon is expected to use in a critical part in space energy harvesting system related with the solar radiation.

• 대한화장품학회지
• /
• 제35권3호
• /
• pp.229-233
• /
• 2009

식물 20종을 메탄올로 추출하여 양성자 빔 조사 에너지양(1, 5, 10 KGray)에 따른 항산화 활성 능을 탐색 하고자 DPPH 라디칼 소거활성과 ABTS free 라디칼 소거 활성에 대하여 조사하였다. 양성자 빔 조사 시 15종류는 활성이 증가하였으나 10 KGray에서 흑축(Pharbitis nil Choisy)은 활성이 감소하였으며, 4종류는 활성변화가 없었다. DPPH 라디칼 소거활성은 1 및 5 KGray에서 유근피(Ulmus macrocarpa) (84 %), 10 KGray (85 %)로 가장 높았으나 10 KGray에서 흑축(Pharbitis nil Choisy)은 6 % 감소하였다. $IC_{50}$값을 무처리구와 빔 조사량에 대한 활성을 비교하면 1 KGray에서 산약(Dioscorea batatas Decne.) 6.3배, 5 KGray에서 천화분(Trichosanthes kirilowii Max.) 2.1배, 산약(Dioscorea batatas Decne.) 2.8배 증가하였다. ABTS free 라디칼 소거활성에서 1 KGray의 양성자 빔 에너지를 조사 했을 경우, 가자(Terminalia chebula Retzius)는 60 % 증가하였다. $IC_{50}$값은 1 KGray 빔 조사 시 0 KGray보다 마황근(Ephedra sinica Stapf) 2.0배, 가자(Terminalia chebula Retz.) 2.5배, 우방자(Arctium lappa Linne) 2.4배 증가하였다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.253-253
• /
• 2010

Rice straw was pretreated with aqueous ammonia in order to enhance enzyme digestibility. Soaking in ammonia aqueous (SAA) was conducted with 15% ammonia, at $60^{\circ}C$. for 24 h. Optimization of both saccharification conditions and enzyme loading of SAA rice straw was carried out. Especially enzyme loading test was performed using statistical method. Moreover proton beam irradiation (PBI) was also performed to overcome the problem which inhibit the enzyme digestibility at 1-25 kGy doses with 45 MeV of beam energy. Optimal condition for enzymatic saccharification was follows; pH 4.8, $50^{\circ}C$, 60 FPU of enzyme activity, 1:4 ratio of celluase and ${\beta}$-glucosidase. Also, optimal doses of PBI on rice straw and SAA-treated rice straw for efficient sugar recovery were found to be 3 kGy, respectively. When saccharification was performed with optimal condition, glucose conversion yield was 89% of theocratical maximum in 48 h, and 3 kGy of PBI was applied to SAA-treated rice straw, approximately 90% of the theoretical glucose yield was obtained in 12 h. The results of X-ray diffractometry (XRD) support the effect of both SAA and PBI on sugar recovery, and scanning electron microscopy (SEM) images unveiled the physical change of the rice straw surface since rugged rice straw surface was observed.

• 한국진공학회지
• /
• 제21권5호
• /
• pp.225-232
• /
• 2012

수명 측정법과 동시 계수 도플러 넓어짐 양전자 소멸 분광법으로 p형과 n형 실리콘 시료에 3.98 MeV 에너지를 가진 $0.0{\sim}20.0{\times}10^{13}\;protons/cm^2$ 양성자 빔 조사에 의한 결함을 측정하여 실리콘 결함 특성에 대하여 조사하였다. 양전자와 전자의 쌍소멸로 발생하는 감마선 스펙트럼의 전자 밀도 에너지를 수리적 해석 방법인 S-변수와 열린 부피 결함에 대한 측정법으로서 양전자 수명 ${\tau}_1$과 ${\tau}_2$, 이에 따른 밀도 $I_1$과 $I_2$를 사용하여, 시료의 구조 변화를 측정하였다. 본 연구에서 측정된 S-변수와 양전자 수명은 시료에 조사된 양성자 조사량의 변화에 따라 결함이 증가하였으며, 양전자 수명 측정과 같은 경향을 보여준다. SRIM의 결과로써, 양성자 조사 에너지에 따른 Bragg 피크 때문에 양성자는 시료의 특정 깊이에 주로 결함을 형성하여 시료 전체에는 결함으로 잘 나타나지 않기 때문이다. 빔의 조사량에 따른 결함의 영향이 더 큰 것으로 나타났다.

• Journal of Korean Neurosurgical Society
• /
• 제57권5호
• /
• pp.315-322
• /
• 2015

Intracranial germ cell tumors (ICGCT) occur in 2-11% of children with brain tumors between 0-19 years of age. For treatment of germinoma, relatively low radiation doses with or without chemotherapy show excellent 10 year survival rate of 80-100%. Past studies showed that neoadjuvant chemotherapy combined with focal radiotherapy resulted in unacceptably high rates of periventricular tumor recurrence. The use of generous radiation volume which covers the whole ventricular space with later boost treatment to primary site is considered as standard treatment of intracranial germinomas. For non-germinomatous germ cell tumors (NGGCT), 10-year overall survival rate is still much inferior than that of intracranial germinoma despite intensive chemotherapy and high-dose radiotherapy. Craniospinal radiotherapy combined with cisplatin-based chemotherapy provides the best treatment outcome for NGGCT; 60-70% of overall survival rate. There is a debate on the surgical role whether surgery can contribute to improved treatment outcome of NGGCT when added to combined chemoradiotherapy. Because higher dose of radiotherapy is required for treatment of NGGCT than for germinoma, it is tested whether whole ventricular irradiation can replace craniospinal irradiation in intermediate risk group of NGGCT to minimize radiation-related late toxicity in the recent studies. To minimize the treatment-related neural deficit and late sequelae while maintaining long-term survival rate of ICGCT patients, optimized administration of chemotherapy and radiotherapy should be selected. Use of technically upgraded radiotherapy modalities such as intensity-modulated radiotherapy or proton beam therapy is expected to bring an improved neurocognitive outcome with longitudinal assessment of the patients.

• 공업화학
• /
• 제21권4호
• /
• pp.401-404
• /
• 2010

GDC (Gadolinium doped ceria) 펠렛에 120 keV 및 5 MeV 에너지의 양성자 또는 제논 이온을 주입하였으며, 그 영향을 UV-vis 분광계, SEM 및 XRD를 이용하여 측정하였다. GDC 펠렛은 cubic fluorite 구조를 갖는 조밀한 소결체였으며, 갈색이었던 펠렛이 이온빔을 조사한 후 옅은 검은색을 띠기 시작하였으며, fluence가 증가함에 따라 색도 짙어졌다. XRD 패턴은 이온의 에너지 및 X선의 투과 깊이와 밀접한 관계가 있었으며, 120 keV의 양성자 빔을 조사한 표면 바로 아래층은 이온의 주입으로 결정 구조는 유지한 채 격자 상수가 증가하였다는 것을 관찰하였다.