• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1992-1993
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• 2007

Decay processes of accumulated charge in e-beam irradiated polymers during elevating temperature are observed using pulsed electro-acoustic measurement system. Since the polymeric materials have many superior properties such as light-weight, good mechanical strength, high flexibility and low cost, they are inevitable materials for spacecrafts. In space environment, however, the polymers sometimes have serious damage by irradiation of high energy charged particles. When the polymers of the spacecraft are irradiated by high energy charged particles, some of injected charges accumulate and remain for long time in the bulk of the polymers. Since the bulk charges sometimes cause the degradation or breakdown of the materials, the investigation of the charging and the decay processes in polymeric materials under change of temperature is important to decide an adequate material for the spacecrafts. By measuring the charge behavior in e-beam irradiated polymer, such as polyimide or polystyrene, it is found that the various accumulation and decay patterns are observed in each material. The results seem to be useful and be helpful to progress in the reliability of the polymers for the spacecraft.

• 대한방사선치료학회지
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• 제9권1호
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• pp.40-45
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• 1997

When therapeutic irradiation is indicated for the orbital tumors, the greatest concern is the risk of radiation-induced cataract. Conjunctival lymphoma is one of the good examples. We would like to report the procedure of the lens shielding device(L.S.D) and the result of irradiated dose to the lens. L.S.D. consistes of two parts : load alloy to attenuate electron beam, and dental acryl which completely covers the lead alloy to avoid discomfort of cornea from contacting directly with cerrobend and side scattering by cerrobend. And for easy location and removal, side bars were made on each side. Radiation doses were meaured with TLD(TLD 3500 Hawshaw). Markus chamber in a polystyrene phantom. The phantom was irradiated with 9MeV electron beams from Clinac 2100C with $6{\times}6cm$ electron cone. The relative dose at 6mm depth where the lens is located was $4.2\%$ with TLD and $5.1\%$ with Markus chamber clinically when 2600 cGy are irradiated to the eyeball, the mapinary dose to the lens will be 109 cGy or 132 cGy, which will significently reduce the cataract.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1863-1870
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• 2023

Molybdenum-99 (⁹⁹Mo) is used for preparing Technetium-99 m (^99mTc), which is the most widely used isotope in nuclear medicine. In this work, a study for ⁹⁹Mo production based on a high-power electron accelerator has been performed as an alternative approach to produce ^99mTc. In this study, Monte Carlo MCNPX2.6 code has been used to examine a novel idea of simultaneous hybrid production of ⁹⁹Mo via both photoneutron and neutron capture reactions using an electron accelerator in heavy water tank. It is expected that this conceptual design including an arrangement of metallic plates of ¹⁰⁰Mo and ⁹⁸Mo produces total activity of 97.5 Ci at the end of 20-h continuous e-beam irradiation (30 MeV, 10 mA).

• Radiation Oncology Journal
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• 제5권2호
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• pp.157-163
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• 1987

It is known that fixed source to skin distance (SSD) cannot be used when the treatment field is sloped or larger than the size of second collimator in electron beam irradiation and inverse square law using effective ssd should be adopted. Effective SSDs were measured in different field sizes in each 6, 9, 12, 15 and 18MeV electron energy by suing NELAC 1018D linear accelerator of Kosin Medical Center. We found important parmeters of effective SSD. 1. Minimum effective SSD was 58.8cm in small field size of $6\pm6cm$ and maximum effective SSD was 94.9cm in large field size of $25\pm25cm$, with 6MeV energy. It's difference was 36.1cm. The dose rate at measuring point was quite different even with a small difference of SSD in small field $(6\times6cm)$ and low energy (6 MeV). 2. Effective SSD increased with field size in same electron energy. 3. Effective SSDs gradually increased with the electron energies and reached maximum at 12 or 15 MeV electron energy and decreased again at 18MeV electron energy in each identical field size. And so the effective SSD should be measured in each energy and field size for practical radiotherapy.

• 공업화학
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• 제24권6호
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• pp.628-632
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• 2013

미세조류 Arthrospira platensis (A. platensis)는 탄수화물, 지질, 단백질, 파이토케미컬 등을 함유하고 있어 경제적으로 가치가 있으며, 바이오디젤이나 기능성 식품 생산에 중요한 자원이다. 균주 개량을 위해 A. platensis에 240 kGy의 선량으로 전자빔을 조사하여 무작위적 돌연변이를 유도하였다. 여러 변이주를 획득하였고, 스크리닝을 거쳐 지질 함량이 높은 변이주, EB29를 선별하였다. EB29의 세포 생장은 야생균주와 유사하였고, 클로로필 함량도 큰 차이를 보이지 않았다. 하지만, nile red로 염색하여 형광 강도로 측정했을 때, EB29의 지질 함량은 야생균주에 비해 7배 증가하였다. 표준 지질 triolein의 표준곡선을 이용한 지질의 반정량 결과, EB29는 $78.6{\mu}g/mL$로 야생균주($41.4{\mu}g/mL$)보다 약 2배 증가하였다. EB29의 지방산 성분도 분석하였는데, gamma-linolenic acid (GLA)와 같은 PUFA가 약 6배 증가하였고 바이오디젤의 질에 영향을 미치는 지방산들도 야생균주에 비해 증가하였다. 따라서 전자빔은 미세조류의 세포 내 PUFA를 축적시키거나, 바이오디젤에 적합한 지방산 성분을 변화시키는데 유용하게 사용될 수 있을 것이다.

• 한국추진공학회지
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• 제19권3호
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• pp.83-88
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• 2015

열차폐 코팅(Thermal Barrier Coating) 기술의 하나로 연구되는 전자빔(EB, Electron Beam) 증착에 사용되는 코팅재료는 증착 공정 중에 고출력의 전자빔이 조사되기 때문에, 균일코팅을 위해서는 증착 중 코팅재료의 형상유지 및 안정한 융탕 형성이 필요하며, 이를 위해 적절한 밀도와 미세구조를 갖춘 잉곳(Ingot) 형태의 코팅소스가 요구된다. 본 연구에서는 8 wt%의 이트리아($Y_2O_3$)가 안정화제로 첨가된 지르코니아(8YSZ) 조성을 활용하여, 고출력 전자빔 조사환경에 사용가능한 잉곳제조를 위해 최적의 원료분말 조건을 확보하고자 하였다. 제조된 잉곳시료들에 대한 전자빔 조사 시, 수십 마이크론과 수십 나노 크기의 입자들로 구성된 혼합형 분말로 제조된 잉곳의 경우, 나노크기의 분말만으로 제조된 경우보다 향상된 열충격 저항성을 보였다.

• Radiation Oncology Journal
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• 제36권2호
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• pp.153-162
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• 2018

Purpose: We aimed to evaluate clinical outcomes including progression-free survival (PFS), overall survival (OS), partial response, and complete response in patients who underwent radiation therapy (RT) for mycosis fungoides (MF). Also, we sought to find prognostic factors for clinical outcomes. Materials and Methods: Total 19 patients confirmed with MF between 1999-2015 were retrospectively reviewed. Clinical and treatment characteristics, clinical outcomes, and and toxicities were analyzed. Results: Eleven patients were treated with total skin electron beam radiotherapy (TSEBT) and 8 patients with involved field radiation therapy (IFRT) with median dose of 30 Gy, respectively. The median time interval from diagnosis to RT was 2.6 months (range, 0.4 to 87.3 months). The overall response rate was 100%; 11 patients (57.9%) had a complete response and 8 patients (42.1%) a partial response. The presence of positive lymph node at the time of consultation of RT was associated with lower OS (p = 0.043). In multivariate analysis, PFS was significantly lower for patients with increased previous therapies experienced following RT (p = 0.019) and for patients showing PR during RT (p = 0.044). There were no reported grade 3 or more skin toxicities related with RT. Conclusion: Both IFRT and TSEBT are effective treatment for MF patients. Patients with short disease course before RT or complete response during RT are expected to have longer PFS. Positive lymph node status at the initiation of RT was associated woth poor OS, suggesting other treatment modalities such as low-dose RT for patients with low life-expectancy.

• 한국식품과학회지
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• 제31권5호
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• pp.1159-1163
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• 1999

국내외 식품산업에서 방사선 조사 기술이 본격적으로 이용됨에 따라 방사선 조사식품의 조사 여부 검지(detection)와 조사/흡수선량(absorbed dose)의 확인 방법이 필요하게 되었다. 본 연구는 상업적으로 처리되고 있는 효소분말을 대상으로 감마선과 전자선을 조사하고$(2.5{\sim}15\;kGy)$ ESR signal intensity와의 상관관계를 구해 본 결과, 높은 유의성을 보여 주었다(감마선 $R^2$=0.9904; 전자선 $R^{\;2}$=0.9696). 조사 여부 검지에 필요한 threshold value는 비조사구(n = 20)가 1.19(최대값), 2.5 kGy 조사구(n = 20)가 최소값으로 6.97(감마선) 및 7.36(전자선)으로 나타났다. 이상의 threshold value를 이용하여 30개의 미지시료(unknown samples)에 대한 검지시험(blind test)을 실시하여 본 결과, 방사선 조사된 것과 조사되지 않은 시료의 판정이 정확하였다. 한편 dose-effect curve로부터 2가지 회귀식을 구하여 흡수선량 예측에 적용하여 보았을 때 2차회귀식이 $4{\sim}7\;kGy$ 범위의 감마선 및 전자선 조사 시료에 대하여 적용가능성이 높았다.

• 한국축산식품학회지
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• 제30권5호
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• pp.780-786
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• 2010

This study compared the effects of autoclaving (AC; $121^{\circ}C$ for 15 min), gamma (GR), and electron beam irradiation (EB; 0-20 kGy) on the microbial, physicochemical, and sensory properties of ready-to-eat bulgogi during storage at $35^{\circ}C$ for 90 d. No viable cells were observed (p<0.05) upon AC, GR or EB at more than 15 kGy. However, adverse effects such as tenderization and deterioration of sensory properties were induced in bulgogi upon AC and high dose irradiation. Especially, the hardness and sensory qualities (texture and taste) of the AC-treated samples were extremely deteriorated (p<0.05). These results indicate that use of GR and EB (15 kGy) can ensure the microbial safety of bulgogi without compromising the hardness and sensory properties (texture, taste and flavor).

• 한국축산식품학회지
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• 제29권6호
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• pp.680-684
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• 2009

The effects of garlic and onion on the microbiological and physicochemical properties of irradiated ground beef patties were evaluated. Ground beef was mixed with 0.5%(w/w) minced garlic or 2.5%(w/w) minced onion, vacuum-packed in oxygen-impermeable nylon/PE bags and then electron beam-irradiated at 2.5 kGy. All samples were kept at $4^{\circ}C$ for 8 d. Irradiation resulted in a 2-log CFU/g reduction in both aerobic and coliform bacteria. The microbial counts gradually increased during storage, but those in beef that contained garlic or onion were 1-log CFU/g lower than those of the control samples after 8 d of storage. The pH value decreased during storage in all meat samples, but this decrease was greater in non-irradiated beef than in irradiated beef. The lipid oxidation, volatile basic nitrogen content and Hunter color values of raw patties were generally not affected by irradiation or the addition of garlic and onion. Sensory evaluation of cooked patties showed that the off-odor was less pronounced in samples that contained added garlic or onion than in control samples, and that the overall acceptability of beef formulated with garlic was the highest. Overall, the results of this study indicate that the addition of garlic or onion in combination with irradiation treatment enhanced the microbial quality and improved the sensory quality of irradiated ground beef.