• 생물환경조절학회지
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• 제9권4호
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• pp.230-236
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• 2000

제주지방에서 양파 저장에 관한 ${\gamma}$-ray 처리와 저장장소에 대한 실험을 하였다. 발아율은 저온저장, 상온저장, 동굴저장에 관계없이 무처리 양파는 약 5개월 째부터 발아와 발근이 시작되었고 시간이 지날수록 증가하였으나 8월 상순경에는 0krad에서 동굴에 저장한 것은 50%, 상온에 저장한 것은 20%의 발아율을 나타내었다. 그러나 3krad, 6krad 처리한 것은 6개월까지는 거의 발아하지 않았다. 중량 감소는 발아와 밀접한 관계가 있는데 발아가 시작하기 전 40일 까지는 모든 처리에서 차이가 없었지만 발아가 시작되면서부터 급격히 감소하였다. 저온저장한 것은 부패율이 약 5~10% 내외로 7개월 후에도 식용이 가능하였으나 상온에 저장한 것은 0krad에서 50%정도 부패한 반면 3krad 및 6krad를 조사한 것은 저온저장인 경우 5%, 동굴저장인 경우 30~35%, 상온에 저장한 것은 30% 정도의 부패율을 나타내었다. 방사선조사의 다당류 변화에 대한 연구는 비교적 많이 이루어졌는데 동굴저장과 상온저장에서는 저장초기에는 3krad 및 6krad 조사한 것이 0krad 보다 다소 증가했으나 후기로 갈수록 역시 처리한 것이 양은 적으나 0krad보다는 증가한 사실을 알 수 있었다. Allum속 채소류에 많이 들어있는 유황은 저장장소에 관계없이 0krad에서는 저장후반기로 갈수록 적어졌고 냉장저장한 것은 3krad 및 6krad의 선량간에는 다소 차이가 있었으나 저장초기에는 유황함량이 증가하다가 12월 말경 부터는 점차 감소하는 경향을 보였다.

• Journal of Radiation Protection and Research
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• 제31권4호
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• pp.197-201
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• 2006

Daily and seasonal variations of the ambient gamma ray exposure rates were measured by using a pressurized ion chamber from January 2003 to December 2005 in the CheongJu Regional Radiation Monitoring Post and the patterns of the distributions were studied. The annual average of the daily variation of the exposure rate was $\sim0.17{\mu}R/h$. The exposure rate was found to be maximum during 8:00 am to 9:00 am and minimum during 8:00 pm to 10:00 pm. For the annual data, the exposure rate was the minimum during the month of February. The exposure rate increased from February to mid-October (except during the period from May to July with no change) and decreased from October to February. The seasonal variation was found to be about $1{\mu}R/h$. Most of the measured values (96%) of the exposure rates fell under the normal distribution with a deviation of less than 4.8% and the remaining 4% had large fluctuations caused mainly by the rainfalls.

• 한국식품과학회지
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• 제28권3호
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• pp.482-489
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• 1996

건고추를 통고추와 분말고추로 구분하고 감마선 조사기법을 이용, 포장재별(통고추; PC 마대 및 PE/PC 마대, 분말고추; NY/PE - laminated film) 및 저장온도별 품질 안전성 시험을 수행하여 위생화와 장기 안전저장성을 검토하였다. 건고추(통고추)는 실온조건에서 6개월 저장후 기존의 PC마대로 단독포장한 경우에 중량변화, 해충발생, 변색, 성분변화 등의 품질열화로 상품가치를 완전 상실하였으나, PE/PC병용포장후 5-7.5 kGy 범위의 감마선 조사는 실온에서 2년간 장기 안전저장이 가능하였다. 7.5-10 kGy 조사된 분말고추에서도 실온 및 저온($5-10^{\circ}C$)에서 2년간 저장동안 양호한 위생적, 이화학적, 관능적 품질을 유지하였다.

• Nuclear Engineering and Technology
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• 제7권2호
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• pp.85-94
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• 1975

n형 Ge 결정체를 보상하기 위해 상온에서 $^{60}$Co 감마선으로 647 Mrad 조사하였다. 감마선으로 조사된 Ge 결정체로 Ge(${\gamma}$) 검출기를 제작하였다. Ge(${\gamma}$) 검출기의 검출기 특성은 얇은 Ge(Li) 검출기나 고순도 Ge 검출기와 비슷하였다. Ge(${\gamma}$) 검출기의 온도에 대한 안정도는 상온에서의 저장이 가능함을 보여 주었다.

• Nuclear Engineering and Technology
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• 제51권8호
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• pp.1991-1997
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• 2019

In this manuscript, we present a method for the direct calculation of an ambient dose equivalent (H^* (10)) for the external gamma-ray exposure with an energy range of 40 keV to 2 MeV in an electronic personal dosimeter (EPD). The designed EPD consists of a 3 × 3 ㎟ PIN diode coupled to a 3 × 3 × 3 ㎣ CsI (Tl) scintillator block. The spectrum-to-dose conversion function (G(E)) for estimating H^* (10) was calculated by applying the gradient-descent method based on the Monte-Carlo simulation. The optimal parameters for the G(E) were found and this conversion of the H^* (10) from the gamma spectra was verified by using ²⁴¹Am, ¹³⁷Cs, ²²Na, ⁵⁴Mn, and ⁶⁰Co radioisotopes. Furthermore, gamma spectra and H^* (10) were obtained for an arbitrarily mixed multiple isotope case through Monte-Carlo simulation in order to expand the verification to more general cases. The H^* (10) based on the G(E) function for the gamma spectra was then compared with H^* (10) calculated by simulation. The relative difference of H^* (10) from various single-source spectra was in the range of ±2.89%, and the relative difference of H^* (10) for a multiple isotope case was in the range of ±5.56%.

• 한국식품영양과학회지
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• 제25권3호
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• pp.484-490
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• 1996

Physicochemical changes were determined for the boiled-dried anchovies packaged in a laminated film(nylon 15${\mu}{\textrm}{m}$/polyethylene 100${\mu}{\textrm}{m}$) and stored for one year at ambient and cooling(5~1$0^{\circ}C$) temperatures after gamma irradiation. Lipophilic and hydrophilic browning pigments increased with storage time particularly at ambient temperature, even though initial 5 kGy irradiation did not affect the formation of pigments significantly. This results were confirmed by the instrumental color determinations, Hunter color L, a, b and ΔE. With respect to changes in relative fatty acid compositions, storage period and temperature were more influential factors than gamma irradiation. Irradiation at 5 kGy induced insignificant changes in the total flavor profiles of stored anchovies, which were mainly composed of n-dodecanal(26.7%), n-pentadecane(22.2%), n-octanal(4.9%) and 2-pentylfuran(3.4%).

• Journal of Radiation Protection and Research
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• 제42권3호
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• pp.158-165
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• 2017

Background: Nuclear facilities in South Korea have generally adopted pressurized ion chambers to measure ambient gamma ray exposure rates for monitoring the impact of radiation on the surrounding environment. The rates assessed with pressurized ion chambers do not distinguish between natural and man-made radiation, so a further step is needed to identify the cause of abnormal variation. In contrast, using NaI(Tl) scintillation detectors to detect gamma energy rates can allow an immediate assessment of the cause of variation through an analysis of the energy spectra. Against this backdrop, this study was conducted to propose a more effective way to monitor ambient gamma exposure rates. Materials and Methods: The following methods were used to analyze gamma energy spectra measured from January to November 2016 with NaI detectors installed at the Korea Atomic Energy Research Institute (KAERI) dormitory and Hanbat University. 1) Correlations of the variation of rates measured at the two locations were determined. 2) The dates, intervals, duration, and weather conditions were identified when rates increased by $5nSv{\cdot}h^{-1}$ or more. 3) Differences in the NaI spectra on normal days and days where rates spiked by $5nSv{\cdot}h^{-1}$ or more were studied. 4) An algorithm was derived for automatically calculating the net variation of the rates. Results and Discussion: The rates measured at KAERI and Hanbat University, located 12 kilometers apart, did not show a strong correlation (coefficient of determination = 0.577). Time gaps between spikes in the rates and rainfall were factors that affected the correlation. The weather conditions on days where rates went up by $5nSv{\cdot}h^{-1}$ or more featured rainfall, snowfall, or overcast, as well as an increase in peaks of the gamma rays emitted from the radon decay products of $^{214}Pb$ and $^{214}Bi$ in the spectrum. This study assumed that $^{214}Pb$ and $^{214}Bi$ exist at a radioactive equilibrium, since both have relatively short half-lives of under 30 minutes. Provided that this assumption is true and that the gamma peaks of the 352 keV and 1,764 keV gamma rays emitted from the radionuclides have proportional count rates, no man-made radiation should be present between the two energy levels. This study proved that this assumption was true by demonstrating a linear correlation between the count rates of these two gamma peaks. In conclusion, if the count rates of these two peaks detected in the gamma energy spectrum at a certain time maintain the ratio measured at a normal time, such variation can be confirmed to be caused by natural radiation. Conclusion: This study confirmed that both $^{214}Pb$ and $^{214}Bi$ have relatively short half-lives of under 30 minutes, thereby existing in a radioactive equilibrium in the atmosphere. If the gamma peaks of the 352 keV and 1,764 keV gamma rays emitted from these radionuclides have proportional count rates, no man-made radiation should exist between the two energy levels.

• Environmental Analysis Health and Toxicology
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• 제22권2호통권57호
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• pp.111-118
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• 2007

This study was performed to measure gaseous Organochlorine Pesticides (OCPs : heptachlor epoxide, ${\alpha}/{\gamma}-chlordane$, trans-nonachlor, endosulfan, ${\gamma}-HCH$ and p, p'-DDE) concentration using PUF high volume sampler from June, 2000 to June, 2002 in the semi-rural atmosphere. Using monitoring data for two years, we tried to investigate the annual cycles of gaseous OCPs. We considered three functions to describe the annual cycle: Gaussian, Lorentzian and sinusoidal functions. These functions accounted for $54{\sim}91%$ of the variability in concentration for each gaseous OCPs, and the sinusoidal function gave the best fits. It was seen that the gaseous OCPs concentration increased during the warmer weather while decreased during colder weather. The variation of the gaseous OCPs concentration was closely similar to the variations of ambient temperature. The annual cycle of endosulfan was strongly higher than in comparison with other gaseous OCPs, while for ${\gamma}-HCH$, the cycle was weakly high and did not show apparent seasonal variation. The position of the annual maximum exists generally late July to early August. The period that showed levels more than a half maximum was from late June to early September.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.183-190
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• 2001

The activity concentration of primordial radionuclides i.e., $^{238}U$ series, $^{232}Th$ series and $^{40}K$, in soil samples collected from Udagamandalam environment, have been measured by employing NaI (Tl) Gamma ray Spectrometer. The absorbed gamma dose rate has also been simultaneously measured by using both Environmental Radiation Dosimeter at each soil sampling location (ambient gamma dose) as well as from the gamma dose derived from the activity concentration of the primordial radionuclides. The results of activity concentration of each radio nuclides in soil, absorbed dose rate in air due to soil activity and possible cosmic radiation at each location along with human effective dose equivalent for Udagamandalam environment are presented and discussed.

• Applied Science and Convergence Technology
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• 제24권6호
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• pp.273-277
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• 2015

We investigated secondary electron emission characteristics of ZnO thin films prepared by pulsed laser deposition method with respect to the ambient oxygen pressure and the substrate temperature during the deposition. X-ray diffraction, UV-Vis spectrometry, atomic force microscopy, and ${\gamma}$-FIB were used to examine the structural, optical transmission, surface morphology, and secondary electron emission properties of the films, respectively. The secondary electron emission coefficient of the ZnO films increases as the O/Zn ratio of the films increases which was thought to result from either the ambient oxygen pressure increase or the substrate temperature decrease and as the grain size of the films decreases. It was confirmed that ZnO has better secondary electron emission characteristics than those of MgO, which is currently widely used as a material for PDP protecting layers.