• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.150-151
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• 2011

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.503-510
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• 2020

Concrete is one of the most widely used materials as the shielding structures of a nuclear facilities. It is also the most generated radioactive waste in quantity while dismantling facilities. Since the concrete captures neutrons and generates various radionuclides, radiation measurement and analysis of the sample was fulfilled prior to dismantle facilities. An HPGe detector is used in general for the radiation measurement, and effective correction factors such as geometrical correction factor, self-absorption correction, and absolute detector efficiency have to be applied to the measured data to decide exact radioactivity of the sample. Correction factors are obtained by measuring data using a standard source with the same geometry and chemical states as the sample under the same measurement conditions. However, it is very difficult to prepare standard concrete sources because concrete is limited in pretreatment due to various constituent materials and high density. In addition, the concrete sample obtained by core drill is a volumetric source, which requires geometric correction for sample diameter and self absorption correction for sample density. Therefore in recent years, many researchers are working on the calculation of effective correction factors using Monte carlo simulation instead of measuring them using a standard source. In this study we calculated, using Geant4, one of the Monte carlo codes, the correction factors for the various diameter and density of the concrete core sample at the gamma ray energy emitted from the nuclides ¹⁵²Eu and ⁶⁰Co, which are the most generated in radioactive concrete.

• Progress in Medical Physics
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• v.14 no.2
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• pp.69-73
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• 2003

In this study, we measured shielding block correction factors for irregular fields and compared them with published data for the square blocked field. We devised a methods to measure the factors at an arbitrary depth in phantom. The measurements were performed for 12 shielding blocks used in radiation therapy. The measured correction factors for irregular blocked fields were consistent within $\pm$0.5% with those of the square blocked fields. Our results show that the shielding block correction factors for the typical square blocked fields can be used in clinical dose calculations for irregular blocked fields. However, for small fields, we suggest that verification be done by measurement.

• Journal of the Korean Society of Radiology
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• v.5 no.5
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• pp.261-265
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• 2011

The purpose of this study is to calculate correction factors for energy dependence of a nanoDotdosimeter to measure patient's skin dose in diagnostic radiography. The correction factors were calculated by using the values of mean energy for the RQR standard radiation qualities of IEC publicated by Rosado et al. and the energy response graph of dosimeter relative X-ray on phantom calibration provided by landaur corporation. Results showed the correction factors of 1-1.33 over the tube voltage range of 40-50 kVp. Acquired correction factors are considered to be useful in the clinics for the measurement of accurate skin dose at each tube voltage.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.4
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• pp.295-300
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• 2015

The precise determination of the activity for each radionuclide in environmental samples requires the self-absorption correction factor. In this research, we derived the self-absorption correction factor for three p-type high purity germanium detectors using the Monte Carlo code MCNPX. These detectors have different characteristics such as crystal diameter, height and size of the core. We compared the calculated full-energy peak efficiency with the experimental value using a standard sample with $1g/m^3$ density and verified the modeling. We simulated the dependency of the full-energy peak efficiency on the 0.3, 0.6, 0.9, 1.0, 1.2 and $1.5g/m^3$ samples and obtained the corresponding self-absorption correction factor. The self-absorption correction factors calculated for the three detectors differ by less than 1% over most of the energy range and sample densities considered. This indicates that the self-absorption correction factors are independent of the crystal characteristics of HPGe detector.

• Progress in Medical Physics
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• v.2 no.1
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• pp.17-28
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• 1991

Generally, it is an accurate radiation measurement technique for processors fo thermoluminescent dosimenters(TLDs) to characterize each element they use by producing element correction factors(FCFs). TLDs are classified into three groups such as reference. control, and field TLDs. Reference TLDs are used only for the production of ECFs for the control and field TLDs. They are kept locked in a safe place except when it is necessary to use a subset of them to produce ECFs for the control and field TLDs. The ECF of a given element is a measure of the response of the element relative to the mean response of an arbitrarily selected group of reference elements. As TLDs are used in the field, their relative responses to radiation might be decreased due to muliple readings and physical abuse. Therefore, the producditon of ECFs are performed initially and periodically during the field use. This element correction method provides an excellent tool to examine new TLDs and to monitor the reliability of old TLDs. This paper discuss the 10 step procedures developed to produce and examine ECFs.

• Journal of Radiation Protection and Research
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• v.31 no.4
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• pp.165-171
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• 2006

In Korea, a real-time effective dose measurement system is in development. The system uses 32 high-sensitivity MOSFET dosimeters to measure radiation doses at various organ locations in an anthropomorphic physical phantom. The MOSFET dosimeters are, however, mainly made of silicon and shows some degree of energy and angular dependence especially for low energy photons. This study determines the correction factors to correct for these dependences of the MOSFET dosimeters for accurate measurement of radiation doses at organ locations in the phantom. For this, first, the dose correction factors of MOSFET dosimeters were determined for the energy spectrum in the steam generator channel of the Kori Nuclear Power Plant Unit #1 by Monte Carlo simulations. Then, the results were compared with the dose correction factors from 0.652 MeV and 1.25 MeV mono-energetic photons. The difference of the dose correction factors were found very negligible $(\leq1.5%)$, which in general shows that the dose corrections factors determined from 0.662 MeV and 1.25 MeV can be in a steam general channel head of a nuclear power plant. The measured effective dose was generally found to decrease bit $\sim7%$ when we apply the dose correction factors.

• Journal of radiological science and technology
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• v.31 no.1
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• pp.89-95
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• 2008

The quality correction factor for used beam and qualities is strongly required for clinical dosimetry by TRS-398 protocol of IAEA. In this study the quality correction factors for a commercial plane-parallel ionization chamber in high energy electron beams were calculated by Monte Carlo code(DOSRZnrc/EGSnrc). In comparison of quality correction factor, the difference between this study and TRS-398 were within 1% in 5-20 MeV. In case of 4MeV the difference was 1.9%. As an independent method of determination of quality correction factor this study can be applied to evaluate values in the protocol or calculate the factor for a new chamber.

• Korean Journal of Remote Sensing
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• v.14 no.2
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• pp.117-128
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• 1998

Topex/Poseidon satellite, launched in Auguest 1992, has provided more 5 years of very good quality data. Efficient improvements, either about instrumental accuracy or about sea level data correction, have been made so that Topex/Poseidon has become presently a wonderful tool for many researchers. The first mission data of 73 cycles, September 1992 - August 1994, was used to our study in order to know characteristics of environmental correction factors in the Amsterdam-Crozet-Kerguelen region of the South Indian Ocean. According to standard procedures as defined under user handbook for sea surface height data processes, then we have chosen cycles 43 as the cycle of reference because this cycle has provided the completed data for measurement points and has presented the exacted position of ground track compared to another cycles. It was computed variations of various factors for correction in ascending ground track 103(Amsterdam-Kerguelen continental plateau) and descending ground track170 (Crozet basin). Here the variations of ionosphere, dry troposphere, humid troposphere, electromagnetic bias, elastic tide and loading tide were generally very smaller as a few of cm, but the variations of oceanic tide(30-35cm) and inverted barometer(15-30cm) were higher than another factors. For the correction of ocean tide, our model(CEFMO: Code d' Elements Finis pour la Maree Oceanique) - This is hydrodynamic model that is very well applicated in all oceanic situations - was used because this model has especially good solution in the coastal and island area as the open sea area. Conclusionally, it should be understood that the variation of ocean free surface is mainly under the influence of tides(>80-90%) in the Amsterdam - Crozet- Kerguelen region of the South Indian Ocean.

• Korean Journal of Digital Imaging in Medicine
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• v.17 no.1
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• pp.9-12
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• 2015

임상용 모니터의 출력값 중 가장 큰 영향을 주는 것이 휘도이다. 최근 컬러 모니터의 임상용 사용으로 인해 출력값의 보정은 매우 중요하게 관리되고 있다. 색보정 변위의 특성화가 휘도와 동일한 인자로 영향을 주는지 분석하기 위해 사용된 특성화 보정 모델은 GOG모델과 S-curve모델 이다. 두 개의 모델을 통해 모니터의 휘도는 장치의 출력과 직접적인 관계가 있다는 것을 증명하고 동일한 출력에 입력값을 가질 수 있도록 구성하고자 한다. 동일한 출력을 디스플레이 할 경우 동일한 출력값을 얻어야 한다. 그러나 모니터에 따라 서로 다른 출력값을 산출한다. 컬러모니터의 경우는 출력의 안정성에 휘도뿐만 아니라, 색감(R,G,B) 변화가 큰 역할을 수행한다. 본 연구에서는 분석인자 중 대조도에 영향을 주는 인자를 역추적하여 특성화 보정 S-curve모델을 LCD에 적용하였다. 이는 GOG모델을 적용한 CRT와 동일한 결과를 얻었다. 따라서 인자는 CIEXYZ의 결과값과 동일한 인자를 구할 수 있다.