• 상하수도학회지
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• 제18권6호
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• pp.731-741
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• 2004

The purpose of this study was to evaluate the potential of a gamma ray irradiation to decompose hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in an aqueous solution. The decomposition reaction of RDX by gamma ray irradiation was a first-order kinetic over the applied initial concentrations (10-40mg/L). The dose constant was strongly dependent on the initial concentration of the RDX. The removal of RDX was more efficient at pH below 3 and at pH above 11 than at neutral pH (pH 5-9). The required irradiation dose to remove 99% of the RDX (40mg/L) was 4, 8 and 1 kGy, at pH 2, 7 and 13, respectively. The dose constant was increased by two folds and over twelve folds at pH 2 and 13, respectively, when compared with that at pH 7. When an irradiation dose of 20 kGy was applied, the removal efficiencies of TOC were 80, 57 and 91% at pH 2, 7 and 13, respectively. Ammonia and nitrate were detected as the main nitrogen byproducts of RDX and formic acid was detected as an organic byproduct. The results showed that a gamma ray irradiation was an attractive method for the decomposition of RDX in an aqueous solution and it was found that a strong alkaline pH over 12 should be applied to the decomposition reaction of RDX.

• 한국작물학회지
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• 제53권2호
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• pp.150-155
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• 2008

양성자와 감마선 조사한 추파형 유채 $M_2$세대의 화뢰의 소포자 배발생에 대해 조사하였다. 세 가지 유채품종 '한라', '내한'과 '탐미' 유채종자를 각각 400 Gy와 600 Gy의 양성자와 감마선으로 전처리 하였다. 일부 종의 양성자와 감마선 조사구에서 배발생이 증가되었고 대조구보다 높았다. 품종별로는 '내한'유채가 배발생 빈도가 가장 높았고 '탐미' 유채가 가장 낮았다. 드물게 배상체로부터 바로 소식물체가 형성되었고 대부분은 비정상적으로 multilobe가 형성되었다. 배상체로부터 식물체가 성공적으로 재분화 되었고 화분에 순화되었다.

• 천문학회보
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• 제41권1호
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• pp.66.1-66.1
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• 2016

We present our observational results of BL Lacertae(2200+420) obtained at 22, 43, 86, and 129 GHz simultaneously during 27 months(2013.Jan ~ 2015.Mar) which includes their two gamma-ray outbursts(2013.Oct & 2015.Mar) to study a connection between the gamma-ray outbursts and the radio activity. We mainly use a Korean VLBI monitoring program, IMOGABA(Interferometric Monitoring Of Gamma-ray Bright AGNs) which is a monthly monitoring program with the KVN(Korean VLBI Network). Overall, our KVN image shows two components in the map, a stationary core at the center and one moving jet component to the south, but almost core only at 86, 129 GHz. The location of the moving jet component in the maps depend on the frequencies that 22, 43, 86, and 129 GHz. We have checked light curves, spectral index, kinematics, and radio structure to find differences before and after the gamma-ray outbursts, but there was no significant correlation. We also have derived a decay time scale of ~9 months for the major radio outburst by applying an exponential decay fitting.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.1121-1124
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• 2015

본 연구에서는 광대역 펄스감마선 탐지센서 최적화설계에 관한 연구를 수행하였다. 펄스감마선 탐지센서는 $1{\times}10^6{\sim}1{\times}10^8rad(Si)/s$의 방사선량에서 동작할 수 있도록 설계하였다. 에너지에 따른 펄스감마선 스펙트럼과 시간에 따른 에너지 비율을 기반으로 탐지센서 입력변수를 도출하고, 탐지감도 제어회로를 기반으로 탐지센서 출력전류를 도출하였다. N-type Epi Wafer를 이용하여 최적조건 탐지센서를 TCAD기반으로 설계하였다. 시뮬레이션 결과 인가전압 3.3V에서 최적 Epi층 두께는 45um다. 도핑농도는 N-type은 Arsenic으로 $1{\times}10^{19}/cm^3$, P-type은 Boron으로 $1{\times}10^{19}/cm^3$, Epi 층은 Phosphorus로 $3.4{\times}10^{12}/cm^3$다. 마지막으로 탐지센서는 원형으로 지름이 1.3mm 이다.

• 방사선산업학회지
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• 제6권3호
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• pp.211-215
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• 2012

In this study, crosslinked polyethylene (PE) foam sheets were prepared through gamma-ray irradiation. PE foam sheets were prepared through a foaming process using sodium bicarbonate as a blowing and foaming agent. The prepared PE foam sheets were then crosslinked through gamma-ray irradiation. The crosslinking degree was increased to 86.0% with an increase in the absorption dose. The tensile strength of the crosslinked PE foam sheets was increased with an increase in the absorption dose. However, the elongation-at-break of the crosslinked PE foam sheets was decreased. The thermal decomposition temperature of the crosslinked PE foam sheets was increased to $421.2^{\circ}C$ with an increase in the absorption dose. The SEM analysis revealed that the morphology was not changed significantly after the crosslinking through gamma-ray irradiation.

• 센서학회지
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• 제24권3호
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• pp.202-207
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• 2015

As a feasibility study on development of a gamma imaging probe, we developed a scintillating film-based gamma imaging detector that can obtain scintillation images with information of gamma-ray distribution. The scintillating film-based gamma imaging detector was composed of a sensing probe, an image intensifier, and a beam profiler. To detect and transmit scintillation image, the sensing probe was fabricated by coupling a scintillating film, a fiber-optic image conduit, and a fiber-optic taper, consecutively. First, the optical images of USAF 1951 resolution target were obtained and then, modulation transfer function values were calculated to test the image quality of the sensing probe. Second, we measured the scintillation images according to the activity of the 137Cs and the distance between the surface of 137Cs and the distal-end of sensing probe. Finally, the intensities of scintillating light as functions of the activity and the distance were evaluated from the region of interest in the scintillation image. From the results of this study, it is expected that a fiber-optic gamma imaging detector can be developed to detect gamma-rays emitted from radiopharmaceuticals during radioimmunoguided surgery.

• Journal of Astronomy and Space Sciences
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• 제29권3호
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• pp.253-258
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• 2012

We revisit the relation between the peak luminosity $L_{iso}$ and the spectral time lag in the source frame. Since gamma-ray bursts (GRBs) are generally thought to be beamed, it is natural to expect that the collimation-corrected peak luminosity may well correlate with the spectral time lag in the source frame if the lag-luminosity relation in the GRB source frame exists. With 12 long GRBs detected by the Swift satellite, whose redshift and spectral lags in the source frame are known, we computed $L_{0,H}$ and $L_{0,W}$ using bulk Lorentz factors ${\Gamma}_{0,H}$ and ${\Gamma}_{0,W}$ archived in the published literature, where the subscripts H and W represent homogeneous and wind-like circumburst environments, respectively. We have confirmed that the isotropic peak luminosity correlates with the spectral time lag in the source frame. We have also confirmed that there is an anti-correlation between the source-frame spectral lag and the peak energy, $E_{peak}$ (1 + z) in the source frame. We have found that the collimation-corrected luminosity correlates in a similar way with the spectral lag, except that the correlations are somewhat less tight. The correlation in the wind density profile seems to agree with the isotropic peak luminosity case better than in the homogeneous case. Finally we conclude by briefly discussing its implications.

• 비파괴검사학회지
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• 제26권3호
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• pp.169-173
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• 2006

In-service diagnoses of pipeline facilities are important for a systematic maintenance of them. Field applications by using sealed gamma-ray sources $(^{60}Co,\;^{137}Cs)$ were performed to identify the heterogeneous zone in the pipelines of a distillation tower and a flare stack respectively. From the results, the heterogeneous zones in the pipelines were successfully identified. In the case of the pipeline connected to the distillation tower, a vapor pocket was detected in the fluid under hydrodynamic conditions, which could explain the reason for a decrease of the flow rate. In another case, an area with some amount of catalyst deposits was found at the bottom of the gas pipeline which was connected to the flare stack. And these findings provided important information for the process operators. Diagnosis technique by using gamma radiation sources has been proven to be an effective and reliable method for providing information on a media distribution in a facility.

• 한국물환경학회지
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• 제22권1호
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• pp.145-149
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• 2006

Textile and pigment wastewater samples collected from an industrial complex showed toxic effect on Daphnia magna. For textile wastewater, 48 h acute toxicity of effluent was not detected while toxic unit (TU) of influent was 1.79. The toxicity of influent was completely disappeared by gamma-ray treatment at 10 kGy or by suspended solids (SS) removal. In case of pigment wastewater, both influent and effluent were toxic to D. magna though the effluent satisfied current water quality standards. Gamma-ray treatment had little effect on the toxicity reduction of pigment wastewater since the toxicity was mainly caused by metal ions, in particular, Cr(VI). This work suggests the bioassay technique for monitoring adverse effects of wastewater should be introduced, and also shows the usefulness of gamma-rays as an advanced treatment technique for textile wastewater.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2002년도 강연요지집
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• pp.97-117
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• 2002

A chemoinfometrical method for quantitative determination of crystal content of indomethacin (IMC) polymorphs based on fourie-transformed near-infrared (FT-NIR) spectroscopy was established. A direct comparison of the data with the ones collected from using the conventional powder X-ray diffraction method was performed. Pure $\alpha$ and ${\gamma}$ forms of IMC were prepared using published methods. Powder X-ray diffraction profiles and NIR spectra were recorded for six kinds of standard materials with various content of ${\gamma}$ form IMC. The principal component regression (PCR) analyses were performed based on normalized NIR spectra sets of standard samples of known content of IMC ${\gamma}$ form. A calibration equation was determined to minimize the root mean square error of the prediction. The predicted ${\gamma}$ form content values were reproducible and had a relatively small standard deviation. The values of ${\gamma}$ form content predicted by two methods were in close agreement. The results were indicated that NIR spectroscopy provides for an accurate quantitative analysis of crystallinity in polymorphs compared with the results obtained by conventional powder X-ray diffractometry.