• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.240-246
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• 2008

The x-ray transmission anode Ag-target tube was developed to apply for the thickness measurement of film in the thickness range of several tens$\sim$several hundreds ${\mu}m$ and its characteristics were evaluated. The energy distribution and dose of x-ray from Ag-target tube was investigated at the tube voltage near 10 kV, and discussed in comparition with that from W-target tube. The energy distribution and dose of x-rays passing through film were measured with various thickness of Ny and PP film. From these results, it was confirmed that our x-ray tube can be applied for the thickness measurement of film.

• Journal of Radiation Protection and Research
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• v.33 no.2
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• pp.53-59
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• 2008

We observed DNA damages as a function of mean absorbed dose to identify the indirect effect of high-energy radiation such as x-ray. Monolayer films of lyophilized pGEM-3Zf(-) plasmid DNA deposited on tantalum foils were exposed to Al $K{\alpha}$ X-ray (1.5 keV) for 0, 3, 7 and 10 min, respectively, in a condition of ultrahigh vacuum state. We compared DNA damages by X-ray irradiation with those by 3 eV electron irradiation. X-ray photons produced low-energy electrons (mainly below 20 eV) from the tantalum foils and DNA damage was induced chiefly by these electrons. For electron beam irradiation, DNA damage was directly caused by 3 eV electrons. Irradiated DNA was analyzed by agarose gel electrophoresis and quantified by ImagaQuant program. The quantities of remained supercoiled DNA after irradiation were linearly decreased as a function of mean absorbed dose. On the other hand, the yields of nicked circular (single strand break, SSB) and interduplex crosslinked form 1 DNA were linearly increased as a function of mean absorbed dose. From this study, it was confirmed that DNA damage was also induced by low energy electrons ($0{\sim}10\;eV$) even below threshold energies for the ionization of DNA.

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.109-117
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• 1995

고에너지 이온주입시 격자결함의 생성 및 열처리 거동이 double crystal X-ray와 단면 TEM을 사용하여 연구되었다. 3MeV P+ 이온주입한 실리콘의 DCXRD 분석 결과조사량 증가에 따라 모재 내의 변형량은 증가하였다. HRTEM 분석 결과 고에너지 이온주입시 결함은 표면 부근에 희박하고 Rp 부근에 집중되어 있었다. 또한 이온주입 상태의 결함층은 dark band의 형태로 존재하였으며 열처리시 이차결함은 이곳으로부터 생성됨이 관찰되었다. 3MeV P+,$1X1015extrm{cm}^2$의 조건으로 이온주입된 실리콘 시편의 열처리에 따른 X-ray rocking curve 분석을 통하여 열처리 온도가 $550^{\circ}C$에서 $700^{\circ}C$로 증가함에 따라 모재 내부의 최대 변형량이 7X10-4에서 2.9X10-4으로 감소함이 관찰되었다. 특히 $550^{\circ}C$ 열처리한 시편의 경우 표면으로부터$-1.5mu$m 영역에 작은 변형층이 넓게 잔존하였으며 열처리온도를 $700^{\circ}C$로 증가한 경우 제거되었다. 이온주입시 생성된 일차결함들은 $700^{\circ}C$ 열처리시 $60^{\circ}$ 전위와 <112> 막대 모양 결함, $1000^{\circ}C$ 열처리시 <110>방향의 전위루프로 열처리 조건에 따라 여러 가지 모양의 이차결함으로 변화하였다. 고에너지 이온주입에 의해 발생한 이차결함은 고온에서도 안정하여 고온 열처리에 의한 제거가 용이하지 않았다.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.355-356
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• 2016

기존 X-ray용 인버터의 경우, 일반적인 Full-bridge 인버터를 사용하여 낮은 효율이 발생하기 때문에 1.6kW이상의 고전압 출력을 요구하는 X-ray를 사용할 수 없는 문제점이 있다. 본 논문은 X-ray 구동용 인버터의 높은 출력이 가능한 고전압 출력용 ZVS Phase-Shift Full Bridge 인버터를 제안한다. 기존의 X-ray 구동용 인버터를 사용할 경우에는 낮은 효율 및 높은 출력 전압을 발생 시킬 수 없기 때문에 X-ray 발생이 어려우며, 높은 출력을 발생시키기 위해서는 회로의 전체적인 부피가 커지고 제작단가가 증가하는 단점이 있다. 반면 제안된 회로는 X-ray 구동용 ZVS Phase-Shift Full Bridge 인버터로써, 영전압 스위칭을 통해 높은 효율로 인버터 구동이 가능하고, 높은 출력 전압을 발생 시킬 수 있기 때문에 회로의 소형화 및 고출력 X-ray 발생이 가능한 장점을 갖는다. 본 논문에서는 제안된 회로의 이론적인 특성을 분석하고 모의실험을 통해 확인하였으며, 1.6kW급 X-ray 구동 인버터 회로에 적용하여 실험을 통해 우수성을 검증하였다.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.18-22
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• 2006

Effects of V substitution of Fe on the magnetic properties of $Fe_3O_4$ have been investigated by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), conversion electron Mossbauer spectroscopy (CEMS), and vibrating sample magnetometry (VSM) measurements on sol-gel-grown films. XRD data indicates that the $V_xFe_{3-x}O_4$ films maintain cubic structure up to x=1.0 with little change of the lattice constant. Analyses on V 2p and Fe 2p levels of the XPS data indicate that V exist as $V^{3+}$ mostly in the $V_xFe_{3-x}O_4$ films with the density of $V^{2+}$ ions increasing with increasing V content. Analyses on the CEMS data indicate that $V^{3+}$ ions substitute tetrahedral $Fe^{3+}$ sites mostly, while $V^{2+}$ ions octahedral $Fe^{2+}$ sites. Results of room-temperature VSM measurements on the films reveal that the saturation magnetization for the x=0.14 sample is larger than that of $Fe_3O_4$, while it becomes smaller than that of $Fe_3O_4$ for $x{\geq}0.5$. The coercivity of the $V_xFe_{3-x}O_4$ films is found to increase with x, attributed to the increase of anisotropy by the substitution of $V^{2+}(d^3)$ ions into the octahedral sites.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.477-482
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• 2015

Workers in nuclear medicine have performed various tasks such as production, distribution, preparation and injection of radioisotope. This process could cause high radiation exposure to wokers' hand. The purpose of this study was to investigate shielding effect for r-rays of 140 and 511 keV by using Monte-carlo simulation. As a result, it was effective, regardless of lead thickness for radiation shielding in 140 keV r-ray. However, it was effective in shielding material with thickness of more than only 1.1 mm in 511keV r-ray. And also it doesn't effective in less than 1.1 mm due to secondary scatter ray and exposure dose was rather increased. Consequently, energy of radionuclide and thickness of shielding materials should be considered to reduce radiation exposure.

• Nuclear Engineering and Technology
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• v.49 no.4
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• pp.792-800
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• 2017

The essential requirement of a material to be used for engineering purposes at nuclear establishments is its ability to attenuate the most penetrating ionizing radiations, gamma $({\gamma})-rays$. Mostly, high-Z materials such as heavy concrete, lead, mercury, and their mixtures or alloys have been used in the construction of nuclear establishments and thus termed as nuclear engineering materials (NEM). The NEM are classified into two categories, namely opaque and transparent, depending on their behavior towards the visible spectrum of EM waves. The majority of NEM are opaque. By contrast, various types of glass, which are transparent to visible light, are necessary at certain places in the nuclear establishments. In the present study, ${\gamma}-ray$ shielding behaviors (GSB) of six glass samples (transparent NEM) were evaluated and compared with some opaque NEM in a wide range of energy (15 keV-15 MeV) and optical thickness (OT). The study was performed by computing various ${\gamma}-ray$ shielding parameters (GSP) such as the mass attenuation coefficient, equivalent atomic number, and buildup factor. A self-designed and validated computer-program, the buildup factor-tool, was used for various computations. It has been established that some glass samples show good GSB, thus can safely be used in the construction of nuclear establishments in conjunction with the opaque NEM as well.

• Proceedings of the Safety Management and Science Conference
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• 2010.11a
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• pp.103-112
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• 2010

This study was done to provide basic data on the safety of professionals in medical imaging system by measuring the electromagnetic waves generated in the medical imaging system being used in medical organization. The studied medical imaging systems were general X-ray system, computed tomography(CT), ultrasonographic system, magnetic resonance imaging(MRI), PET-CT and fluoroscopic system, and through these devices, electric field and magnetic field were measured and analyzed. As a result of the analysis, the measured values classified by the medical organizations were not much significant, but in the measurement by the medical imaging systems, there were high hazard elements in the sequential order of electric field PET-CT($17.7{\pm}22.9$)v/m, CT($10.3{\pm}8.7$)v/m, general X-ray system ($8.8{\pm}8.8$)v/m, magnetic field general X-ray system($5.06{\pm}8.26$)mG, CT($2.71{\pm}4.53$)mG and PET-CT($0.74{\pm}0.34$)mG, the systems that adopted X-ray as main ray source, and the more aged the medical imaging systems, the greater the effects of electro-magnetic waves($10.6{\pm}15.93v/m$ for 5 years or more, $6.14{\pm}5.60v/m$ for 5 years or less). The effects of electromagnetic waves on medical imaging systems or facilities were not much when the notification of ministry of knowledge economy is considered, but in the overall perspective considering all the equipments and facility of the medical organization, such effects were significant. It is determined that sustainable safety managements of electric field and magnetic field must be done during process from medical imaging system installation to maintenance to rule out such factors.

• Journal of the Korea Safety Management & Science
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• v.12 no.4
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• pp.67-72
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• 2010

This study was done to provide basic data on the safety of professionals in medical imaging system by measuring the electromagnetic waves generated in the medical imaging system being used in medical organization. The studied medical imaging systems were general X-ray system, computed tomography(CT), ultrasonographic(USG) system, magnetic resonance imaging(MRI), PET-CT and fluoroscopic(R/F) system, and through these devices, electric field and magnetic field were measured and analyzed. As a result of the analysis, the measured values classified by the medical organizations were not much significant, but in the measurement by the medical imaging systems, there were high hazard elements in the sequential order of electric field PET-CT($17.7{\pm}22.9$)v/m, CT($10.3{\pm}8.7$)v/m, general X-ray system($8.8{\pm}8.8$)v/m, magnetic field general X-ray system($5.06{\pm}8.26$)mG, CT($2.71{\pm}4.53$)mG and PET-CT($0.74{\pm}0.34$)mG, the systems that adopted X-ray as main ray source, and the more aged the medical imaging systems, the greater the effects of electro-magnetic waves($10.6{\pm}15.93v/m$ for 5 years or more, $6.14{\pm}5.60v/m$ for 5 years or less). The effects of electromagnetic waves on medical imaging systems or facilities were not much when the notification of ministry of knowledge economy is considered, but in the overall perspective considering all the equipments and facility of the medical organization, such effects were significant. It is determined that sustainable safety managements of electric field and magnetic field must be done during process from medical imaging system installation to maintenance to rule out such factors.

• Journal of radiological science and technology
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• v.17 no.2
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• pp.21-27
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• 1994

In this pauper, when the X-ray exposure condition is 70, 90, 110 kV, 10 mAs, FFD 180 cm, FSO $10{\times}10$, $35{\times}35\;cm$, toward the $36{\times}36{\times}15\;cm$ acryl phantom, the free space scatter dose rate at the 15th points in X-ray diagnostic room was measured by electrometer and 1800 co ionization chamber. Therefore, the free space scatter dose distribution profile was drown, and then, the free space scatter dose contribution percentage was Investigated. The obtained results are summarized as following. 1. The X-ray tube leakage dose rate of the experiment generator at the 1 m from focus was measured maximum 85 mR/hr, minimum 20 mR/hr, therefore, this values was appeared below the KS rules, 2. The free space scatter dose become to larger at the primary X-ray beam around area, and lower at the back ward X-ray tube. The maximum values were 3,812 mR/hr at the front Lt 1 m $45^{\circ}$ point, minimum 117 mR/hr at the back ward 1 m $180^{\circ}C$ point. 3. As the more tube voltage and field size increase, the more free space scatter dose contribution percentage become to increase, as to 90 kV from 70 kV, increase to 12 %, to 110 kV from 90 kV, increase to 18 %, and then, become to 11 % at the $10{\times}10\;cm$ and 87 % at the $35{\times}35\;cm$. 4. The 89 % of the total producted scatter ray occured from acryl phantom, at the X-ray tube housing 6 %, at the front side back wall 5 %. 5. The free space scatter dose contribution percentage at the one point build up 80 % from the phanton direction, 14 % from the X-ray tube and collimator direction, 2.2 % from the front wall, 1.8 % from the side wall, 1.7 % the back wall.